This invention relates to latch actuator arrangements which are particularly useful for automobile doors, but can also be used for example with other closures such as bonnets, boots and petrol caps, and for non-automotive applications The invention is most beneficially applied to automotive central-locking door arrangements

A major problem with vehicle doors is unauthorised entry for theft, and in one aspect of the invention this problem is minimised by an arrangement which can neutralise the motion of the interior lock control knob, making the door openable only by a key or by automatic central unlocking This would prevent forced entry by operation of the interior lock control knob, for example after breaking a window or by inserting a tool through the door skin

Another major consideration in vehicle manufacture is the cost of components, and another aspect of the invention aims at minimising the cost of latch actuator arrangements, by simplifying them and reducing the number of parts that are required

A further consideration is safety in the event of vehicle accident, and an advantage derived from aspects of the present invention is that the latch arrangement can be made more secure against mechanical shock tending to unlatch the door

The present invention provides a latch actuator arrangement for releasably retaining a striker (10), comprising a pivotally-mounted latch bolt (5) shaped to retain the striker at a latching rotary position and to release the striker at an unlatching rotary position of the latch bolt, a pawl (615) movable between a locking position, at which it retains the latch bolt at its latching rotary position, and an unlocking position at which it allows the latch bolt to move to its unlatching rotary position, means (616; 709, 80) for linking the pawl to a latch-opening external control such as a door handle,

a locking member (625) pivotally mounted for rotation between an unlocking position, and a locking position, at which it allows movement of the said pawl linking means to move the pawl to its unlocking position, at which it either (a) neutralises movement of the pawl linking means with respect to the pawl or (b) blocks movement of the pawl linking means, in each case preventing the pawl linking means from moving the pawl to its unlocking position, means for linking the locking member to at least one external lock control such as a key mechanism and an interior door knob, for mechanical actuation of the locking member betweem its locking and unlocking positions, and powered drive means coupled to the locking member for powered actuation of the locking member between its locking and unlocking positions

This actuator arrangement can be manufactured with fewer components, and at significantly reduced cost, than with previous arrangements. It is also inherently more resistant to accidental unlatching as a result of mechanical shock In the case of vehicle-powered central locking arrangements, the motor means such as pneumatic means or servomotors would require very feeble power consumption, so the overall arrangement becomes much more efficient

An automobile designer ^" s needs for approved adaptability and standardisability can be met with the present invention. A latch actuator embodying the invention can take any of a variety of different configurations, alone as a separate unit, or together with a key mechanism as a single unit, or together with both door latch or key mechanism as a single unit. This also improves the simplicity of vehicle assembly Further, latch actuators embodying the invention can be made relatively compact

Preferably, the locking member is linked to two said external lock controls

Preferably, to minimise the number of components, the locking member is linked directly to a key mechanism and to an interior door knob

In one form, the locking member (625) has an abutment surface which engages a corresponding abutment surface (630) on the pawl only when each is at its locking

j position, so that the locking member blocks movement of the pawl and of the pawl linking means (616).

Alternatively, the pawl linking means comprises an intermediate activation member (709) which the latch-opening external control selectively couples to the pawl, and is drivingly coupled to the locking member (725) for movement between a coupling position, at which the locking member is at its unlocking position and the external control is coupled to the pawl for unlatching it, and a neutral position, at which the locking member is at its locking position and the external control is decoupled from the pawl

The invention also concerns a complete automobile door central locking system comprising any of the latch actuators as defined above

In order that the invention, in its various aspects, may be better understood, preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings, of which

Figure 1 is a schematic vertical cross section through a novel latch actuator arrangement outside the scope of the invention;

Figure 2 is an alternative form of latch actuator arrangement;

Figure 3 is a third form of latch actuator arrangement, omitting some of the parts for the sake of clarity;

Figure 4 is yet a further alternative latch arrangement

Figure 5 is an example of a modification of the arrangement of Figure 1, with selective coupling to the door handle linkage

Figures 6A and 6B show two different configurations of a first embodiment of the invention in which the interior lock control knob can be rendered neutral, and

Figure 7 is a schematic diagram of a latch actuator as a second embodiment of the invention

By way of background to the invention, the arrangements shown in Figures 1 to 5 will be described In Figure 1, a door latch actuator arrangement contained in a suitable housing is mountable on a door frame at a mounting point 1 1 and at other points The arrangement is intended to detain releasably a striker 10 which is normally

a U-shaped rigid metal rod of cylindrical cross section, secured rigidly to the vehicle frame (not shown) The latch arrangement on the door would engage the striker 10 in an arcuate path, in the direction from right to left in Figure 1, from its open to its closed

position As is well known, a latch bolt 5 has a generally U-shaped recess for accommodating the striker 10 and for causing rotation of the latch bolt 5 about its pivot against spring action The latch bolt 5 is rotatable between a latched position, shown in Figure 1, and an unlatched position (not shown) rotated clockwise through approximately 56°

A pawl for locking the latch bolt 5 consists of two linked parts 15, 16 A first part 15 is pivotally mounted on the housing structure at 13 and has a straight shoulder 18 This first part 15 is pivotally linked at 14 to a second part 16 which includes a tooth with an active surface 17, for engaging in either of two notches 50, 55 in the latch bolt 5 The second part 16 also has a shoulder 19, which abuts against shoulder 18 to prevent pivotal rotation beyond the position shown in Figure 1 The second part 16 is formed with a pin 21 engaging in a slot 46 in a rigid control arm linkage 45 for connection to the door handle

At the fully closed position shown in Figure 1, the latch bolt 5 is locked by the pawl 15, 16 The pawl is rotationally biased anticlockwise, for example by a spiral spring (not shown)

The latch bolt 5 has a half-latch position, rotated approximately 26° clockwise from that shown in Figure 1, at which the notch 50 is at the position shown for notch 55 in Figure 1 At this position, the latch bolt can be locked by the pawl, whose surface 17 locks into the notch 50 Further clockwise rotation of the latch bolt 5 is then possible only by releasing the pawl again, and the latch bolt then moves to its fully clockwise position (not shown), which is fully unlatched At this cocked position, the latch bolt 5 is ready to receive the striker 10 once again, when the door is reclosed At this unlatched position, the outer surface 56 of the latch bolt prevents movement of the pawl to its locking position As will also be described below, surface 56 also prevents movement of a locking member 25 towards its locking position, as shown in Figure 1

A servomotor 40 is part of the vehicle central locking system, and is permanently coupled through gearing 95, 195 to a shaft 90 which is connected through worm gears 70, 75 to a locking member 25. Locking member 25 is in the form of a block constrained to move linearly, from left to right in Figure 1, by means of rails 80 co-operating with formations 85 in the housing. The shaft 90 also rotationally drives an actuation plate 20, constrained to move vertically in Figure 1 The coupling between the shaft 90 and the actuation plate 20 is by means of a toothed rack 60 and a spur gear

65

The actuation plate 20 is pivotally mounted at 1 10 to a rigid link arm 35 for connection to an interior lock control knob The plate is also coupled, with a degree of vertical play, to a rigid link arm 30 for connection to a key mechanism (not shown), by way of a pin 105 on the plate 20, engaging in a slot 100 in the link arm 30

There is thus a permanent mechanical linkage between the servomotor, the locking member 25, the interior knob link arm 35 and the key mechanism link arm 30

The function of the novel locking member 25 will now be described The locking member translates between an extreme locking position, as shown in Figure 1, and an unlocking position (not shown) to the left of that position At its unlocking position, the actuation plate 20 is raised to its extreme upwards position, and no restraint is made either on the latch bolt 5 or the pawl 15, 16 or the linkage 45. At this position, the latch bolt 5 will have rotated clockwise to its cocked or unlatched position (not shown), and its surface 56 prevents motion of the locking member 25 towards its locking position, by the abutment of surfaces 56 and 81 This ensures that the actuator does not latch until the door has been shut, or at least half shut.

Once the door has been shut, and the striker 10 has caused anti-clockwise rotation of the latch bolt 5 either to its half latch or its full latch position, the pawl 15, 16 will have sprung back into engagement in the respective notch 50 or 55 At this latching position, the locking member 25 is free to move to its locking position, at which its abutment surface 82 will abut against the tooth of the second part 16 of the pawl, as well its abutment surface 83 Abutment surface 83 will prevent clockwise rotation of the pawl, so will prevent unlatching This locking movement of the locking member 25 can be initiated either by the servomotor 40, or by downwards pressure on

the interior knob through link arm 35, or by operation of the key mechanism and downward pressure on the link arm 30 Reversal can be achieved by upwards motion of the interior knob or the key link arm 30, or reversal of the operation of the servomotor

40.

In the configuration shown in Figure 1, an abutment surface 84 on the locking member 25 also assists in preventing movement of the locking member towards its locking position, when the pawl is at its unlatching position, because surface 84 will abut against the surface of tooth on the second part 16 of the pawl

A second example is shown in Figure 2. Parts corresponding to those of Figure 1 are given the same reference numerals, and will not be described again. In this example, the pawl 215 operates from a different side, and is differently shaped. However, it is still operated by the door handle through the linkage 45 The equivalent of the actuation plate 20 of Figure 1 is an actuation plate 220 in Figure 2. In this example, the equivalent of the locking member 25 is a block 225, driven from the shaft 90 by gearing 270. Block 225 has an under surface which abuts against a surface 265 on the upper surface of the pawl 215, for locking the pawl. Block 225 moves between a locking position, at its extreme left as shown in Figure 2, and an unlocking position, at its extreme right Again, the actuation plate 220 is mechanically linked through gearing to the shaft 90.

The important feature of the arrangement of Figure 2 is the interlock between the interior knob mechanism and a fixed part 200 of the housing.

The link arm 35 for the interior knob is connected pivotally at pin 255 to a triangular plate 235 which has at one corner a pin 230 riding in a cam slot 275 with an L shape, formed in the actuation plate 220. The triangular plate 235 forms a tooth 245 at its other veπex, for releasably engaging in a notch 250 in the fixed part 200. A torsion spring (not shown) biases the plate 245 anti-clockwise, so that as the plate 235 is moved vertically upward in Figure 2, and the pin 230 reaches the corner in the cam slot 275, it can be rotated clockwise, against the spring action, by the camming action of the upper surface of the notch 250 on tooth 245, as the pin 230 follows portion 260 of the cam slot This occurs as the actuation plate 220 rises, under pressure from the key mechanism or the servomotor. Once the plate 235 has rotated clockwise, its tooth 245

will have rotated clear of the notch 250, so allowing the interior knob link arm 35 to move relative to the housing fixed part 200 If then the latch is relocked by the key or the servomotor, the plate 235 would re-engage in the notch 250, and prevent subsequent unlocking by the interior knob If however it is relocked by the knob, downward pressure on link arm 35 prevents re-engagement in the notch 250 Thus if the latch has been locked by the key or the servomotor, then the interior knob will be incapable of unlocking it, because its link arm 35 will be locked against the housing 200 However, if the latch has been locked by the interior knob, then the interior knob will have been kept free from the notch 250, and it will be capable of unlocking the latch

A third example is illustrated schematically, only in part, in Figure 3 Only the link arms 30 and 35 are shown, and only a portion of the pawl 315 is shown The equivalent of the locking member 25 is a block 325, which has formed in it a cam slot 370 consisting of straight end portions joined by a diagonal portion The equivalent of the actuation plate 20 is a plate 320, formed with a pin 375 arranged to follow the cam slot 370, so that vertical motion of the actuation plate 320 is converted into lateral translational motion, from left to right in Figure 3, of the block 325 This causes the block 325 selectively to lock the pawl 315

A significant feature of the arrangement of Figure 3 is the stop bolt 380, formed with a pin 385. and spring biased by a compression spring 395 in the leftwards direction of Figure 3 The pin 385 rides in a C-shaped cam follower slot 390 in the actuation plate 320 This arrangement serves to detain the actuation plate 320, against spring bias, at either of its fully locking or fully unlocking positions, for extra security against mechanical shock It thus provides means for urging the locking member into its locking or unlocking position, as the case may be, from an intermediate position thereof, so as releasably to assist in its detention at that locking or unlocking position

A similar spring-biased detention mechanism is shown in the alternative mechanism illustrated in Figure 4 An actuation plate 420 is releasably retained at either of its extreme positions by means of a spring 415 contained in the latch actuator

housing, and acting on the lateral surface of the plate 420, which is formed with detent notches 410, 41 1

In this particular arrangement, a locking member 425 for the pawl 415 is connected to a rotary gear 400, pivotally mounted at 401 on the housing, and this connection is by way of a pin 402 in the gear 400, riding in an elongate slot 426 formed in the locking member 425 The gearing 400 is driving coupled to a crown gear 405 on the shaft 90

The actuation plate 420 is drivingly coupled to the shaft 90 through gearing 440, 441

A modification of the arrangement in Figure 1 will now be described with reference to Figure 5. For extra security, the door handle linkage 545 may be rendered neutral whenever the locking member 525 is at its locking position, as shown in Figure 5 This is achieved, in this example, by a selective coupling arrangement between the link arm 545 and the pawl 15, 16 A plate 550 is mounted pivotally at 51 1 on the end of the door handle link arm 545, and is spring biased by a spring 510 in the clockwise direction The plate 550 is formed with an inner cut-out 512 constituting an elongate cam surface, with a lateral notch 513 A pin 527 formed on the second part 16 of the pawl rides in the cam slot 512, and selectively couples vertical motion of the link arm 545 with the pawl 16. An extension 526 on the right hand side of the locking member 525 urges the plate 550 anticlockwise, as shown in Figure 5, when at its locking position This decouples the pin 527 from the notch 513, rendering neutral the link arm 545 In the unlocking position of the locking member 525, the link arm 545 is re¬ engaged with the pawl 16, because the plate 550 springs back clockwise

A first embodiment of the invention is illustrated in Figures 6A and 6B The latch bolt 605 and pawl 615 arrangement are similar to those shown in Figure 2; the pawl 615 pivots at 617, and has a pin 616 for connection through a link arm to the door handle In this example, however, the locking member and actuation plate are effectively combined into a single rotary plate 625, mounted pivotally at 627 to the housing The rotary motion of the plate 625 is coupled through gearing 626 to the shaft

90. An abutment surface 630 on the pawl 615 engages a corresponding surface on the rotary plate 625, causing locking of the pawl when at the position shown in Figure 6A

The key mechanism is connected to the rotary plate 625 through a pin 628 and link arm

(not shown).

In this example, the interior lock control knob is coupled releasably through link arm 635 to the rotary plate 625, by the engagement of a tooth 670 into a notch 675 in the rotary plate. Engagement is shown in Figure 6A, and disengagement is shown in Figure 6B

The arrangement is such that the interior knob is capable of unlocking the latch only if it has previously been responsible for locking the latch Also, it will be appreciated that in this example the locking member is not constrained to move linearly: its function is taken by the rotary plate 625. ln this example, a mechanism causes disengagement of tooth 670 from notch 675 whenever the mechanism is locked by clockwise rotation of the rotary plate 625 This could typically be arranged by providing a frictional resistance to the vertical motion of the link arm 635, which more than matches the force for resilient lateral deformation of the link arm 35 to allow disengagement of the tooth 270. If the door is locked manually by downwards pressure of the interior knob, then the knob will stay coupled to the rotary plate 625, and will enable a passenger to unlock the door in this way

It is an important feature of the invention that the rotary locking member links the motor, the door key and the door knob, preferably by direct mechanical linkages

This minimises the number of components and renders their design relatively simple. Further, the rotary locking member is less subject to unwanted mechanical shocks than the translational locking members of Figures 1 to 5

In the variation shown schematically in Figure 7, the door handle control acts through an elongate intermediate activation plate 709, to which the handle linkage 80 is pivoted at a joint 710. An extension lever 707 integral with the rotary locking member 725 is drivingly coupled via pivot point 708 to the activation plate 709 so as to move it generally parallel to its length. Thus anti-clockwise rotary motion, from the unlocking to the locking position (as shown) slides the activation plate 709 in the direction of

arrow 715 The activation plate is guided by a pin 712 on the pawl 615 pivot point which projects through an elongate longitudinal slot 71 1 in the activation plate 709 An end portion 713 has a lateral lug which engages a lateral projection 714 on the pawl only when the activation plate is slid to its unlocking position, towards the left in Figure

7 This engagement effectively couples the activation plate rotatingly to drive the pawl whenever the handle is lifted At the locking position shown, the door handle is free to move but its effect is neutralised, and the latch bolt cannot be unlatched.

Although various examples of this invention have been given with reference to the drawings, these are not intended to be limiting, and it will occur to the skilled reader that many alternative embodiments and modifications are possible Combinations of various features of the different examples given could be made