Latch assembly

Abstract: A latch assembly (8) including a latch bolt (10) moveable between a closed position at which it is capable of retaining a striker (14) and a open position at which it is capable of releasing a striker, the latch assembly further including a pawl (18) moveable between a retaining position at which it is capable of retaining the latch bolt in at least it closed position and a released position at which the latch bolt is free to move between its open and closed position, in which the pawl is rotatably mounted via a rotating element bearing (22)

Description: The present invention relates to latch assemblies and latch arrangements in particular for use on car doors. Manufacturers of cars have been endeavouring to reduced in-car noise, and in particular wind induced in-car noise. One way of achieving this is to provide for door seals which, when a door is in the fully closed position exert a higher force between the door and adjacent door surround. However, the problem with such arrangement is that it becomes increasingly difficult to unlatch the door since those components that secure the door in a latched position e.g. a latch bolt (such as a claw) and a pawl, are under increased load resulting in higher friction. In particular where the door is to be opened by a power actuator, larger and more expensive power actuators are required to be specified in order to be ensure correct unlatching of the door. Significant friction forces are thus developed at the pivot point of a pawl and therefore these forces can be reduced by installing a rotating element bearing at this position. EP0978609 shows a latch arrangement according to the preamble of claim 1 in which a pawl is pivotally mounted on a pin. The pin is mounted on a cam which in turn may be pivotally mounted via a ball or needle bearing. An object of the present invention is to provide a latch assembly and a latch arrangement which is easy to release and at the same time offers safety in case of a collision. Thus according to the present invention there is provided a latch assembly as defined in accompanying claim 1. Such an arrangement means that a separate outer race and or inner race need not be provided. The applicant has realised that the material that the pawl and pawl pivot pin are made from is of sufficient quality to act as bearing race material. In particular the structural integrity of the pawl and pawl pivot pin are important when the vehicle is involved in a collision, in as much as their failure could result in the door opening thus jeopardising the safety of the car occupants and it is for this reason that they tend to be manufactured from high grade steel. The invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is a schematic view of a claw and pawl of a latch assembly according to the present invention: Figure 2 is a isometric schematic view of a door including a latch arrangement according to the present invention: Figure 2a is a section view of the door of figure 2 taken in the direction of arrow A. Figure 3 is schematic view of part of figure 2. With reference to figure 1 there is shown a latch bolt in a form of a claw 10 pivotable about a claw pin 12 between a closed position (as shown in figure 1) wherein a striker 14 is retained in a mouth 16 of the claw and an open position (not shown) wherein the striker is no longer retained in the mouth 16. A pawl 18 is further pivotable about a pawl pivot pin 20 between a retaining position (as shown in figure 1) wherein it prevents the claw from rotating in an anticlockwise direction as shown in figure 1 thus securing the striker 14, to a released position wherein the pawl no longer contacts the claw, thus allowing the claw to rotate in an anticlockwise direction as shown in figure 1 thus releasing the striker. In this case the pawl 18 is pivotally mounted on the pawl pivot pin by a rotating element bearing shown generally as item 22. In this case the rotating element bearing comprises an outer race 24 which is integral with the pawl 18, rotating elements 26 in this case being needle rollers, and an inner race 28 being integral with the pawl pivot pin 20. In further embodiments the rotating elements could be of another form, such as ball bearings or roller bearings. Also in further embodiments a separate outer bearing race could be provided which is rotationally secured in a hole of the pawl for example by an interference press fit. In yet further embodiments a separate inner race could be provided which is rotationally secured to the pawl pivot pin, for example by an interference press fit. In this case the pawl is connected to a power actuator 30 (shown schematically) via a connection means 32 (again shown schematically). Operation of the power actuator moves the pawl from its retained position to its release position thereby allowing release of the striker. In particular the applicant is the first to realise that by providing a relatively complicated bearing arrangement for the pawl (when compared to known plain bearing arrangement) then saving can be made in terms of cost and size when specifying the power actuator since the forces required to open the door are now reduced and thus a smaller and lesser power actuator can be specified. With reference to figures 2 and 3 there is shown a latch arrangement shown generally as item 34 including a latch assembly 36. Latch assembly 36 includes a latch bolt 40 and a pawl 42, operation of which is similar to claw 10 and pawl 18 as described above. In particular is should be noted that in this case pawl 42 is mounted by a plain bearing arrangement on pawl pivot pin 44. The latch arrangement further includes an inside door handle 38 which is connected to pawl 42 by a transmission path 46 (only part of which is shown). Transmission path 46 includes a rod 48 which connects the inside door handle to an inside release lever 50 (also of the transmission path). It should be understood that the term release lever is to be understood as a lever which is situated in a transmission path between an inside door handle and the pawl but which is not in the transmission path between an outside door handle and a pawl. Inside release lever 50 includes an array of teeth 52 which are engagable with an array of teeth 54 of a latch release lever 56 pivotally mounted on the latch assembly 36. It should be understood that the term latch release lever refers to a lever which is situated in a transmission path between an inside handle and the pawl, and is also in the transmission path between an outside handle and the pawl. Thus upon operation of the inside door handle end 56A of latch release lever 56 is caused to move downward in the direction of arrow C. End 56A ultimately connected to the pawl 42 by further components of the latch assembly 36 such that it causes the pawl to move to its released position allowing the claw 40 to rotate in an anticlockwise direction as shown in figure 4 thus releasing the striker. An outside door handle (not shown) has a transmission path which acts in the direction of arrow D on end 56A of latch release lever 56 thus also causing the claw 40 to release the striker. It will be noted from figure 2 that the latch arrangement 34 is mounted on a door 58 of a vehicle 60 (only part of which is shown). It is convenient to define axis of the vehicle as follows:- X axis is defined as the fore and aft direction: The Y axis is defined as the lateral i.e. side to side direction: And the Z is defined as the vertical direction. It can be seen that the door defines a major plain which is substantially parallel to the plain defined by the X and Z axes. Furthermore the rod 48 lies substantially parallel to the Z axis, the inside release lever 50 is pivotable about an axis substantially parallel to the Y axis. Figure 2A shows a cross section view of door 58. In particular it can be seen that door 58 has an inner skin 58A and an outer skin 58B. The door is pivoted about effective pivot point P. The latch assembly 36 is mounted on a rear face 62 of the door and a line L joining effective pivot point P with latch assembly 36 is perpendicular to the plane of rear face 62. In view of the fact that the effective pivot point P is towards an outer portion of the door and the latch assembly is towards an inner portion of the door it can be seen that line L is angled (in this case at 7°) relative to the plain of the inner skin 58A. As such the inner skin 58A is angled relative to the rear face 62 by 97° and thus inside release lever 50 is similarly pivoted about an axis which is at 97° to the axis about which latch release lever 56 pivots. In further embodiments the angle between the door inner skin and the rear face may vary. In particular the angle may be 110° and similarly the angle between the axis of rotation of the inside release lever and latch release lever can be up to 110°. It is preferable that the axis of rotation of the inside release lever intersects the axis of rotation of latch release lever, but this need not be the case. In particular it is possible for these axes to be skew relative to each other whilst the first and second gear teeth can still co-operate to open the latch. In this particular case the arrays of teeth 52 and 54 (shown schematically) are of involute bevel form. Thus as the inside door handle 38 is operated the bevel involute surfaces of the teeth mesh together and during at least part of the opening movement of the inside release handle a rolling action occurs between the contacting involute bevel teeth. This rolling action significantly reduces friction between the inside release lever 50 and the latch release lever 56 thus enabling the door to be opened more easily. In particular where the latch is opened by an actuator, the power actuator can act through the gear teeth.

Claims: A latch assembly (8) for a vehicle including a latch bolt (10) moveable between a closed position at which it is capable of retaining a striker (14) and a open position at which it is capable of releasing a striker, the latch assembly further including a pawl (18) moveable between a retaining position at which it is capable of retaining the latch bolt in at least its closed position and a released position at which the latch bolt is free to move between its open and closed position, in which the pawl is rotatably mounted via a rotating element bearing (22) wherein said rotating element bearing includes at least one of an inner or an outer race, characterised in that said inner race is integral with a pawl pivot pin and/or said outer race is integral with the pawl. A latch assembly as defined in Claim 1 in which the rotating element bearing (22) includes needle roller rotating elements (26). A latch assembly as defined in any preceding claim further including a power actuator (30) operable to move the pawl to its released position. A latch assembly as defined in any preceding claim including a first release lever (50) being pivotable about a first axis and having plurality of first gear teeth (52) and a second release lever (56) operably connected to the pawl and being pivotable about a second axis and having a plurality of second gear teeth (54) for co-operation with the plurality of first gear teeth, operation of the first release lever causing the second release lever to unlatch the latch in which the first axis is not parallel to the second axis. A latch assembly as defined in claim 4 in which the first axis is angled between 70° and 110° relative to the second axis. A latch assembly as defined in claim 4 in which the first axis is substantially perpendicular to the second axis. A latch assembly as defined in claim 4 in which the first axis is skew relative to the second axis. A latch assembly as defined in any one of claims 4 to 7 in which the plurality of first gear teeth (52) have a substantially involute form. A latch assembly as defined in any one of claims 4 to 8 in which the plurality of second gear teeth (54) have a substantially involute gear form. A latch assembly as defined in any one of claims 4 to 9 in which the first release lever is an inside release lever (50). A latch assembly as defined in claim 10 in which the first axis is substantially perpendicular to a major plane of an associated door. A latch assembly as defined in any one of claims 4 to 11 in which the second release lever is a latch release lever (56). A latch assembly as defined in claim 12 in which the second axis lies substantially in a major plane of an associated door. A latch assembly as defined in claim 13 in which the second axis is substantially horizontal. A latch assembly as defined in any one of claims 13 or 14 in which the second axis lies substantially in a fore and aft direction of an associated door. A latch assembly as defined in any one of claims 4 to 12 in which the plurality of first gear teeth and the plurality of second gear teeth provide a bevel gear arrangement. A latch assembly as defined in any preceding claim in which the latch bolt is in the form of a pivotable claw (10).

Inventors: FISHER SIDNEY, FISHER, SIDNEY
Applicants: ARVINMERITOR LIGHT VEHICLE SYS, ARVINMERITOR LIGHT VEHICLE SYSTEMS (UK) LTD
Application year: 2001
Main classification: E05B65
IPC codes: E05B17, E05B65