Sensor for vehicle door latch

Abstract

 A vehicle door latch includes a pair of electrical contacts (20, 21) for actuating e.g. a courtesy light and/or warning lights to show that a door is not properly closed. A pivotally mounted bolt (15) of the latch mounts freely rotatable metal sleeve (19) on a pin (18), the sleeve passing between the contacts to complete the circuit and its rotation providing a wiping action to ensure good contact. Preferably the circuit is only completed when the bolt is not at the fully latched position at which the door is properly closed.

Description

[0001] This invention relates to door latches for motor vehicles and is concerned with the provision of sensor means for providing an Indication or signal to the effect that the latch is in its fully latched condition.

[0002] In one existing construction a microswitch is mounted on the back plate of'the latch and the latch bolt is provided with a small projection positioned to engage the contact of the microswitch when the latch is in its fully closed position, the arrangement being such that,. if the vehicle ignition switch is actuated when the door latch is not fully closed and thus the microswitch is not operated, a warning light is actuated on the vehicle dashboard.

[0003] It is an object of the invention to provide a vehicle latch having a sensor mechanism which is less expensive than the microswitch arrangement referred to above. More specifically it is an object of the invention to provide a vehicle latch having a sensor mechanism including a self-cleaning action so that it will be extremely reliable throughout its working life.

[0004] According to the present invention there is provided a vehicle latch which has a generally U-shaped pivotally mounted latch bolt arranged for engagement with a keeper, wherein the bolt is provided with a projecting pin on which an electrically conductive sleeve is rotatably mounted, the bolt being movable between a position in which the sleeve is located between a pair of contacts to complete an electrical circuit and a position in which the sleeve is spaced from said contacts and the circuit is not completed.

[0005] The arrangement is preferably such that the circuit is not completed when the latch bolt is in its fully latched position whereas, when the latch bolt is in its open position or in its first safety or secondary latched position, the circuit is completed. The electrical circuit may include an internal courtesy light with the arrangement such that, when any one or more of the doors of the vehicle is not fully closed, the courtesy light is actuated. The electrical circuit may alternatively or additionally include an indicator light specific to each latch such that the light appropriate to a particular latch is actuated if that latch is not fully closed.

[0006] The latch preferably includes two parallel metal plates between which a moulded plastics housing is located, the U-shaped bolt being mounted on one of a pair of pivot pins extending between the two plates. A pawl for holding the bolt in its fully latched position in engagement with the striker is mounted on the other- of the two pivot pins. The moulded plastics housing preferably includes formations for locating the two contacts, the contacts being mounted on a printed circuit board so as to project therefrom with one of the two contacts arranged to pass through a slot in the plastics housing and the other contact having a U-shaped portion which sits in a recess in a wall of the plastics moulding.

[0007] The projecting pin is preferably a moulded plastics pin which extends from a lobe of the U-shaped latch bolt, and the sleeve is freely rotatable on' the pin so that, as the sleeve passes between the two contacts, it will rotate on the pin to generate a cleaning action and ensure that no one part of the sleeve becomes worn. The two contacts preferably have curvate portions between which the sleeve is arranged to pass so as to effect resiltent deflection of the contacts.

[0008] The invention wilt now be described by way of example with reference to the accompanying drawings which illustrate one form of door latch and in which one sheet illustrates the general form of the latch whilst the other sheet illustrates the contact construction.

[0009] The latch includes a cover plate 10 and a back plate 11 between which a moulded plastics housing 12 is located. Two pivot pins 13 and 14 extend between the two plates 10 and 11. The first pivot pin 13 provides a mounting for a generally U-shaped bolt 15, the pivot mounting including a flanged plastic bush and an elastomeric block which fits round the pin 13 to provide a vibration and sound damping action on closure of the latch. The second pivot pin 14 provides a pivot mounting for a pawl 16 which engages the bolt 15 to hold it in its fully latched condition or in its partially latched condition, the latch components being shown in the drawing in the positions which they occupy when the bolt 15 is in its fully latched position in engagement with a striker (not shown). The latch also includes a number of levers as illustrated to effect the-required locking and unlocking and release functions of the latch.

[0010] The U-shaped bolt 15 has two arms and is mounted with 'the pivot pin 13 passing through the centre of the base of the U. A lobe 17 projects from the base of the U on the side of the pivot pin 13 remote from the two arms of the U, and this lobe 17 is formed with an aperture in which is fitted a moulded plastics pin 18. The pin 18 carries a phosphor bronze sleeve 19 which is freely rotatable on the pin 18. As the latch bolt 15 is pivoted about the axis. of the pin 13 during movement of the bolt 15 into its first safety position and then into its fully open position, the sleeve 19 will pass between a pair of metal contacts 20 and 21 mounted on a printed circuit board 22 slotted into a receiving channel in the moulded plastics housing 12.

[0011] The upper contact 20 has a main curvate portion and a bent end portion 23 which is passed through a slot in the plastics housing 12 in such manner as to locate the contact 20 while permitting . limited resilient deflection thereof when engaged by the sleeve 19. The lower contact 21 has an intermediate portion 24 of generally U-shape which is located within a recess in the plastics housing 12, with the arrangement again such as to permit limited resilient deflection of the contact 21 when engaged by the sleeve 19.

[0012] A diode 25 is mounted on the printed circuit board 22 to prevent feed-back between the different parts of the overall circuit which includes a courtesy light, operated if any one of the vehicle doors is not fully closed, and a plurality of warning lights mounted in a display panel on the vehicle dashboard. A specific warning light is operated to indicate which vehicle door is not fully closed should one or more of the doors not be fully closed when the vehicle ignition switch is actuated.

[0013] The electrical switch constituted by the pair of contacts 20 and 21 and the sleeve 19 is illustrated in the circuit'drawing as 26 and, when closed, provides an electrical connection between a line 27 and a pair of lines 28 and 29.

[0014] As explained above, the sleeve 19 is spaced from the contacts 20 and 21 when the latch bolt 15 is in its fully latched position so that the switch 26 will be open and neither the courtesy light nor the particolar warning light will be actuated. When, however, the latch is partly or fully opened, the sleeve 19 will move into a position between the two contacts 20 and 21. As the sleeve 19 is freely rotatable on its pin 18 and the contacts 20 and 21 are. resiliently di-splaceable positive contact will be established between the sleeve 19 and contacts 20 and 21 to ensure a positive electrical connection and to provide a cleaning action as the sleeve wipes over the contacts. Thus, any corrosive film which might tend to form on the contacts 20 and 21 will be removed during opening and closing of the door. In addition, because the contacts 20 and 21 and sleeve 19 perform the function of a courtesy light switch as well as a sensor, an overall vehicle cost saving is obtained.

Claims

1. A vehicle door latch including a pivotally mounted latch bolt, a keeper for releasable engagement with the bolt to retain the latter at a fully latched position, a pair of electrical contacts, and a projecting pin on the latch bolt on which an electrically conductive sleeve is rotatably mounted, the sleeve being carried between the contacts during movement of the latch bolt to complete an electric circuit in use.

2. A latch as in Claim 1 wherein the circuit is only completed when the bolt is not at the fully ' latched position.. -

3. A latch as in Claim 1 or 2 including two parallel metal plates, first and second pivot pins extending between the plates, the bolt being mounted on the first pivot pin and the keeper in the form of a pawl being pivotally mounted on the second pin, and a moulded plastics housing located between the plates and locating the pair of contacts.

4. A latch as in Claim 3 including a printed circuit board, the contacts being mounted on the latter so as to project therefrom, one of the contacts being arranged to pass through a slot in the housing and the other contact including a U-shaped portion which is seated in a recess in a wall of the housing.

5. A latch as in any preceding claim wherein the contacts include curved portions, the sleeve passing therebetween so as to effect resilient deflection of the contacts.

6'. A latch as in any preceding claim wherein the latch bolt is general U-shaped and includes a lobe from which the pin extends.

7. A latch as in any preceding claim wherein the pin is a moulded plastics pin and the sleeve is formed of metal freely rotatable on the pin.

8. A vehicle door latch substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. Vehicle door latching means including a latch as in any preceding claim and an electrical circuit including at least one light arranged so that the light is energised when the latch bolt is not at the fully latched position.

10. Latching means as in Claim 9 wherein the light is an internal courtesy light.

11. Latching means as in Claim 9 including a plurality of latches as in any preceding claim each associated with a respective door of the vehicle and a plurality of warning lights each associated with a respective latch to indicate whether any of the doors are not fully closed.

12. Latching means as in Claim 11 including an internal courtesy light which is energised if any one of the doors is not fully closed.

13. A vehicle including a latch as in any one of claims 1 to 8 or latching means as in any one of claims 9 to 12.

Drawing