Latch arrangement

Abstract: A latch arrangement including a latch, a release mechanism a manually actuable element and a control means, the latch being operable to releasably retain a striker in use, the release mechanism being capable of being moved by the manually actuable element from a rest position through an unlocked position to a release position wherein it unlatches the latch, the control means having a locked condition at which actuation of the manually actuable element does not cause unlatching of the latch and an unlocked condition at which during an initial movement of the manually actuable element, the release mechanism achieves the unlocked position and during subsequent movement of the manually actuable element, the release mechanism achieves the unlatch position.

Description: The present invention relates to latch arrangements, and in particular latch arrangements for use within doors of cars (automobiles). Known car doors include latches for releasably retaining the car door in a closed position. Such latches can be locked when the car is left unattended or even when an occupant is in the vehicle so as to prevent access to the vehicle by unauthorised people. GB-A-2 350 644, EP-A-1 004 730, FR-A-2 778 940 and DE-A-4 313 248 show examples of such known latches. Such latches can be moved between a locked and unlocked condition either by manual means such as by operating an inside sill button or an exterior key barrel, or they can be powered between the locked and unlocked conditions by a power actuator, which can be controlled remotely by, for example, infra red devices. A problem with such power locking/unlocking is that in the event that power is lost e.g. during a road traffic accident or as a result of a flat battery, it may not be possible to change the state of the lock. Thus where a vehicle is in use and the doors are locked and the vehicle is involved in a road traffic accident, the occupant of the vehicle may find themselves locked in the vehicle immediately following the crash and this clearly has safety implications. Furthermore the power actuator is expensive to produce and manufacture. An object of the present invention is to provide an improved form of latch arrangement. Thus according to the present invention there is provided a latch arrangement as defined in claim 1 Advantageously movement of a door handle therefore provides two functions, namely that of unlocking of the latch mechanism and also release of the latch mechanism. Furthermore the control means can be configured to ensure the latch arrangement remains in a locked condition, independent of actuation of any door handles (inside or outside doors) when necessary. The invention will now be described, by way of example only, with reference to the accompanying drawings in which:- FIGURE 1 is a view of a latch arrangement according to the present invention; FIGURE 1A is an enlarged view of part of the figure 1 FIGURE 1B is a view similar to figure 1A with the magnetic pawl in a different position; FIGURE 2 shows the latch arrangement of figure 1 part way through an opening operation in an unlocked but latched condition; FIGURE 3 shows the latch arrangement of figure 1 at the end of an opening operation in an unlatched condition; and FIGURE 4 shows the latch arrangement of figure 1 wherein an attempt has been made to open the latch whilst in a locked condition. With reference to the figures there is shown a latch arrangement 10 having a latch 12 (only part of which is shown), a release mechanism 16, powered control means 18 and manually actuable elements in the form of inside handle 20 and outside handle 21. The latch 12 is mounted on a car door and is operable to releasably retain a striker mounted on fixed structure of the car, such as a B post or a C post. The latch 12 typically might include a latch bolt in the form of a rotating claw which engages the striker. To ensure the claw retains the striker, a pawl can be provided to retain the latch bolt in its closed position. The pawl includes a latch release element in the form of a pawl pin 14. With the pawl pin 14 in position A as shown in figure 1, closing of the door will cause the rotating claw to engage the striker and the pawl will then retain the striker in the closed position. Movement of the pawl pin 14 to the position B as shown in figure 1 will release the pawl from engagement with the claw thus allowing the striker to be released from the claw and allowing the door to open. Thus with the pawl pin in the position A of figure 1 the latch can be latched to the striker and with the pawl pin in the position B of figure 1 the latch can be unlatched from the striker. The release mechanism includes release lever 26, release link 28, connector link 30 and lock/unlock lever 32. Release lever 26 is pivotally mounted about pivot C on chassis 24 of the latch arrangement. One end 26A of release lever 26 is connected via linkage 34 (shown schematically) to a manually actuable element in the form of an inside handle 20. End 26A is further connected by a further linkage 35 (shown schematically) to a further manually actuable element in the form of an outside door handle 21. Operation of either handle 20 or 21 causes the release lever to rotate clockwise about pivot C. End 26B of release lever 26 is connected via pivot D to end 28A of release link 28. End 28B of release link 28 includes an abutment 22 for engagement with pawl pin 14 as will be further described below. Release link 28 is connected to end 30A of connector 30 by pivot E which is positioned between end 28A and 28B. End 30B of connector 30 is connected to end of arm 32A of lock/unlock lever 32 by a pivot F. Lock/unlock lever 32 further includes arm 32B having pin 37 and arm 32C having abutment 38 and 39. Lock/unlock lever 32 is pivotally mounted about pivot G onto chassis 24. Lock/unlock lever 32 is made from mild steel and hence in particular abutment 38 is made from a ferromagnetic material though in further embodiments this need not be the case (see below). Powered control means 18 includes electromagnet 42 and magnetic pawl 44. Electromagnetic 42 is mounted on chassis 24 and includes windings 46, core 48 and electric leads 50 and 51. Pawl stop 52 is provided on one side of the electromagnet 42. Magnetic pawl 44 includes a permanent magnet and is pivotally mounted about pivot H onto chassis 24. End 44A of pawl 44 includes abutment 54, 56 and 58, which will be further described below. A tension spring 60 is connected to chassis 24 and release lever 26 and acts to bias release lever 26 in an anticlockwise direction when viewing figure 1. A further tension spring 62 (only shown in figure 3 for clarity) biases pin 37 and pivot D together. In further embodiments different forms of springs can be used in particular springs acting in torsion (clock springs) in place of tension springs 60 and 62 to perform the same biasing action. A lock/unlock lever stop 64 is mounted on the chassis 24. As a result of tension spring 62 end 28A of release link 28 is biased into engagement with pin 37. In further embodiments the end of release lever 26 could engage pin 37 as could a part of pivot D. Magnetic pawl 44 has a south pole at end 44B and a north pole at end 44A. Applying DC current to the windings 46 via electric leads 50 and 51 in a first direction will create a magnetic field around the electromagnet which will bias the north pole in end 44A of magnetic pawl 44 to the left when viewing figure 1 i.e. anticlockwise about pivot H until abutment 54 engages pawl stop 52. Applying DC current in a second direction to windings 46 via electric 50 and 51 will cause a different magnetic field to form around the electromagnet such that north pole end 44A of magnetic pawl 44 is biased to the right when viewing figure 1 i.e. clockwise around pivot H until such time as abutment 56 engages end 33 of arm 32C of lock/unlock lever 32 (see figure 1B). Under these conditions abutment 58 is opposite abutment 39 and will prevent rotation of lock/unlock lever 32 anticlockwise about pivot G (see below). Note that to move the magnetic pawl between the positions as shown in figures 1A and 1B it is only necessary to apply a short pulse (e.g. 50 ms) of current to windings 46 in the appropriate direction since under normal circumstances once the magnetic pawl 44 has achieved one of the positions as shown in figures 1A or 1B there are no forces which tend to move it out of that positions. Note that in a preferred embodiment the centre of gravity of pawl 44 is substantially at pivot H since, in the event of a road traffic accident, such an arrangement will not tend to rotate the pawl as a result of acceleration or deceleration occurring during the accident. Note that in a further preferred embodiment a relatively light detent is provided to maintain the magnetic pawl 44 in either of the positions as shown in figure 1A and figure 1B which can nevertheless be overcome by manual operation of the key or by pulsing the electromagnet. It is also possible to prevent rotation of lock/unlock lever 32 anticlockwise about pivot G by applying and maintaining DC current in the first direction to windings 46 since abutment 38 is made from a ferromagnetic material and will therefore be magnetically attracted to electromagnet 42. The powered control means 18 has three conditions namely a first condition at which no power is applied to the windings and the magnetic pawl 44 is in the position as shown in figure 1B. A second condition at which power is supplied and maintained in a first direction to windings 46 thus attracting abutment 38 and ensuring that the magnetic pawl is positioned as shown in figure 1 and 1A. A third condition at which no power is supplied to the windings 46 and the magnetic pawl 44 is in position as shown in figure 1. Operation of the latch arrangement is as follows. With the control means 18 in the third condition the door can be manually opened as follows. As mentioned previously with the control means in the third condition the magnetic pawl is positioned as shown in figure 1 and thus does not restrict rotation of the lock/unlock lever 32 in an anticlockwise direction. Furthermore no power is supplied to the windings 46 and thus the electromagnet also does not restrict movement of the lock/unlock lever 32 in an anticlockwise direction. Initial movement of either the inside handle 20 or outside handle 21 moves the release lever 26 in a clockwise direction about pivot C to the unlocked position as shown in figure 2. It should be noted that lock/unlock lever has rotated anticlockwise about pivot G to a position where arm 32A has come into abutment with abutment 64. It should also be noted that abutment 38 has become disengaged from the electromagnet 42. It can also be seen from figure 2 that end 28A of release link 28 has remained in contact with pin 37. Thus connector 30 and release link 28 have also substantially rotated about pivot G. Note that as shown in figure 2 abutment 22 had become aligned with pawl pin 14. This can be contrasted with the position of abutment 22 as shown in figure 1 where it is not aligned with pawl pin 14. Further movement of the inside or outside door handle moves the release lever 26 from the position as shown in figure 2 to the position as shown in figure 3. In view of the fact that arm 32A of lock/unlock lever 32 is in abutting engagement with abutment 64, lock/unlock lever 32 cannot rotate further in an anticlockwise direction. Thus connector 30 is caused to rotate anticlockwise about pivot F relative to lock/unlock lever 32. This results in abutment 22 of release link 28 moving into engagement with pawl pin 14 and moving it from position A as shown in figure 2 to position B as shown in figure 3. As previously mentioned movement of the pawl pin from position A to position B causes the latch to unlock. When the inside and outside handles are released, spring 60 and spring 62 return the release mechanism 16 and pawl pin 14 to the position as shown in figure 1. Note that whilst the movement of the inside or outside handle and hence movement of the release lever 26 has been described in two stages, such two stage movement is not discernible by a person operating the door handles. Furthermore the mechanism is designed to move seamlessly from the position as shown in figure 3 to the position as shown in figure 1. With the control means in its second condition i.e. DC current supplied to the windings in the first direction and the magnetic pawl is in a position as shown in figure 1 the lock/unlock lever 32 is maintained in the position as shown in figure 1 by magnetic attraction. Thus operation of an inside or outside door handle will cause the release lever 26 to rotate in a clockwise direction as shown in figure 1 which will result in end 28A of release link 28 immediately disengaging pin 37 such that the release lever 26, release link 28 and connector 30 moves to the position as shown in figure 4. It should be noted that whilst abutment 22 has being caused to move, in view of the fact that it was initially mis-aligned with pawl pin 14, such movement has resulted in abutment 22 bypassing pawl pin 14 and not imparting any movement to pawl pin 14. Thus whilst the inside or outside handle has been moved, the door has not become unlatched. It can be seen that with the control means in its second condition, the door latch remains in a locked condition. With the control means in the first condition i.e. where there is no power to the windings 46 but the magnetic pawl 44 is in a position as shown in figure 1B, anticlockwise rotation of the lock/unlock lever is again prevented though this time by co-operation of abutments 39 and 58. Thus actuation of the inside or outside handles will again cause release lever 26, release link 28 and connector 30 to move to the position as shown in figure 4. Consideration of figure 2 shows schematically a power actuator P which is independently operable to release the latch. Further shown schematically is a coded security device 70 in the form of an externally mounted key barrel into which can be inserted a key. Actuation of the key barrel via the key is capable of moving the magnetic pawl between the positions shown in figures 1A and 1B. The latch arrangement is configured such that when the associated vehicle is in use the control means is set to its second condition i.e. power is maintained to the windings. Under such circumstances electric power lost to resistance in the windings 46 can be compensated for by the fact that the engine of the vehicle is running and hence the battery recharging system (such as an alternator) can recharge the battery to ensure it does not go flat. When the vehicle is parked and left unattended the control means can be set to its first condition to lock the latch. Note that the control system does not cause any drain to the vehicle battery in its first condition. The control mechanism can also be set to its third condition when the vehicle is parked and is required to be in an unlocked condition. Note that in the third condition there is no drain on the battery. The control means can be changed between its first and third condition by applying a pulse of electrical power to the windings in an appropriate direction. With the vehicle in use and the control means in its second condition, as mentioned above, the lock/unlock lever 32 is maintained in the position as shown in figure 1 by power been fed to the electromagnet. In the event of a power failure, such as might occur following a road traffic accident, the control means will by definition change to its third condition and hence the doors will become unlocked and occupants of the vehicle will be able to escape from the vehicle. With the vehicle parked and with the control means in its first condition i.e. with the vehicle locked, in the event that the vehicle battery is flattened, perhaps as a result of a interior light being left on, pulsing of the electromagnet to move the control means from the first and third condition to unlock the vehicle will not be possible. However, it is nevertheless possible to manually unlock the vehicle by use of the key and key barrel 70. The key and key barrel can also be used to lock the vehicle if necessary. It should be noted that only when the vehicle is in use is power continually fed to windings 46. When the vehicle is parked power is only momentarily fed to windings 46 to change between the locked and unlocked condition. Such an arrangement therefore significantly reduces the likelihood of flattening the battery when the vehicle is parked but the nevertheless allows opening of the doors in the event of power loss following a road traffic accident. It should be noted that the electromagnet 42 need only be strong enough to retain the lock/unlocked lever 32 in the position shown in figure 1 when the electromagnet is in its second condition i.e. when power is being supplied to the electromagnet. Thus the electromagnet has to strong enough to overcome the forces in tension spring 60 during initial movement of inside or outside handle and it has to overcome the forces in tension spring 60 and 62 during a subsequent movement of the inside or outside handle. Note that the electromagnet is not required to be strong enough to move the lock/unlock lever from the position as shown in figure 2 to a position such that abutment 38 engages with the electromagnet. As mentioned above the control means 18 has two ways of preventing rotation of the lock/unlock lever 32, namely by permanently energisation of the windings 46 or by movement of magnetic pawl 44 to the position as shown in figure 1B. In further embodiments, in particular when no power release P is provided, the control means can be used to simply lock and unlock the vehicle e.g. when parked. As such it is only necessary for the windings 46 to be pulsed to move the magnetic between the positions as shown in figures 1A and figure 1B. As such the electromagnet 42 is not required to attract lock/unlock lever 32 which can therefore be made of a non ferromagnetic material, such as a plastics material. Under these circumstances it is necessary to have a manual override system operable by the inside handle (but not the outside handle) such that when the inside handle is moved the magnetic pawl 44, if in the position as shown in figure 1B, is moved to the position as shown in figure 1A. Once the magnetic pawl is in the position as shown in figure 1A, the latch release mechanism 16 can then operate in its two stage manner i.e. alignment of abutment 22 with pawl 14 followed by movement of pawl 14 from position A to position B as shown in figure 1 to open the latch. Under such an arrangement it is preferable that the release mechanism 16 fully returns to the rest position upon release of the inside handle i.e. abutment 22 becomes mis-aligned with pawl pin 14.

Claims: A latch arrangement (10) including a latch (12), a release mechanism (16), a manually actuable element (20, 21) and a control means (18), the latch (12) being operable to releasably retain a striker in use, the release mechanism (16) including a release link (28) having an abutment (22) operable to move a latch release element (14) said abutment (22) being capable of being moved by the manually actuable element (20, 21) from a rest position (figure 1) through an unlocked position (figure 2) to a release position (figure 3) wherein it unlatches the latch (12), and with the abutment (22) in the rest position, the abutment (22) is misaligned with the latch release element (14), the control means (18) having a locked condition at which starting with the abutment (22) in said rest position (figure 1) actuation of the manually actuable (20, 21) element moves the abutment (22) but the abutment (22) does not move the latch release element (14) and an unlocked condition at which starting with the abutment (22) in said rest position (figure 1) during an initial movement of the manually actuable element (20, 21), the abutment (22) achieves the unlocked position thereby aligning the abutment (22) with the latch release element (14) and during subsequent movement of the manually actuable element (20, 21), the abutment (22) achieves the release position. A latch arrangement (10) as defined in claim 1 in which the release link (28) is operably movable by a release lever (26). A latch arrangement (10) as defined in any preceding claim in which a part (32) of the release mechanism (16) is retained in a rest position by the control means (18) to provide for the lock condition. A latch arrangement (10) as defined in claim 3 in which said part (32) of the release mechanism (16) is retained by magnetic attraction. A latch arrangement (10) as defined in claims 3 or 4 in which said part (32) of the release mechanism (16) is retained by a control pawl (44). A latch arrangement (10) as defined in claims 3 to 5 in which said part (32) of the release mechanism (16) is a lock/unlock lever (32) which is retained in a first position when the control means (18) is in its locked condition and is allowed to moved to a second position when the control means (18) is in its unlocked condition. A latch arrangement (10) as defined in claim 6 in which the lock/unlock lever (32) is connected to the release link (28) by a connector (30). A latch arrangement (10) as defined in claim 7 in which the lock/unlock lever (32), connector (30) and release link (28) substantially move in unison during said initial movement of the manually actuable element (20, 21). A latch arrangement (10) as defined in claim 8 in which the lock/unlock lever (32), connector (30) and release link (28) rotate about a pivot (G) during said initial movement. A latch arrangement (10) as defined in claim 9 in which the pivot (G) mounts the lock/unlock lever (32) on a chassis (24) of the latch arrangement. A latch arrangement (10) as defined in claim 9 or 10 in which the lock/unlock lever (32) remains stationary during said subsequent movement of the manually actuable element (20, 21). A latch arrangement (10) as defined in any preceding claim in which the release mechanism (16) is designed to return the abutment (22) to the rest position from the release position upon release of the manually actuable element (20, 21). A latch arrangement (10) as defined in claim 12 in which the release mechanism (16) is biased to move the abutment (22) to the rest position by resilient means (60, 62). A latch arrangement (10) as defined in claim 13 in which a first resilient means (62) biases the release mechanism (16) to move the abutment (22) to the unlocked position from the released position and a second resilient means (60) biases the release mechanism (16) to move the abutment (22) to the rest position from the unlock position. A latch arrangement (10) as defined in any preceding claim in which the latch (12) is further movable between a latched and released position by a powered released actuator. A latch arrangement (10) as defined in any preceding claim in which the control means (18) is movable between the locked and unlocked conditions by manual operation of a coded security device (70) such as a key. A latch arrangement (20) as defined in any preceding claim in which during said initial movement of the manually actuable element (20, 21), the abutment (22) moves generally arcuately, and during said subsequent movement of the manually actuable element (20, 21), the abutment (22) moves generally linearly.

Inventors: SPURR NIGEL, SPURR, NIGEL
Applicants: ARVINMERITOR LIGHT VEHICLE SYS, ARVINMERITOR LIGHT VEHICLE SYSTEMS (UK) LTD
Application year: 2001
Main classification: E05B65
IPC codes: E05B47, E05B65