A MOTOR VEHICLE DOOR LOCKING SYSTEM

Abstract: A motor vehicle door latching and locking system is disclosed in which a claw member (50) which is used to hold a door assembly (10) in a closed position is acted upon by first and second pawls (44, 42). The first pawl (44) is moveable out of engagement with the claw (50) by means of a power operated actuator assembly (32) controlled by a central control unit (2). The first pawl (44) provides not only latching of the door (10) but also, when the central control unit (2) is placed in a locked condition, provides locking of the door assembly (10).

Description: A Motor Vehicle Door Locking System This invention relates to motor vehicles and in particular to the locking and latching of doors associated with such vehicles. It is well known to provide a motor vehicle with means to latch each of the doors in a closed position and separate locking means to ensure that when the vehicle is left unattended the doors remain locked in a closed position even if the door handles are operated. It is a disadvantage with such prior art arrangements that separate mechanisms for both latching and locking have to be provided. It is an object of this invention to provide an improved and simplified door locking and latching system for a motor vehicle door. According to the invention there is provided a door assembly for a motor vehicle door comprising a door structure and a latch assembly to maintain the door in a closed position, the latch assembly comprising a support member for attachment to part of the door structure to be secured, a claw member pivotally mounted upon said support for movement between a door latching position and a door release position, a first pawl to hold said claw in said door latching position, a second claw engageable with the claw as a secondary latching means and a power operated actuator to move said first pawl out of engagement with the claw. The power operated actuator may be an electric motor. The electric motor may be connected to the first pawl by a worm and gear drive. - 2 - Preferably after release of the first pawl the second pawl may prevent the claw from rotating from the door latching position until it is released. The door assembly may further comprise at least one door release connected by a mechanical linkage to the second pawl to move it to a claw releasing position. The or each door release may have a sensor associated therewith to provide an output signal when the door release is operated. The claw may have a recess for co-operation with a striker attached to part of the body structure of the motor vehicle to provide a means for holding the door in a latched position, the claw being rotatable from the door latching position in which the striker is trapped in the recess to a door releasing position in which the striker can enter or exit the recess when the door is removed. Preferably at least one of the pawls is engageable with the claw to hold it in a part latched position in which the door is prevented from opening but is not held fully closed. Preferably both of the pawls may be engageable with the claw to hold it in a part latched position. Advantageously the support member for the latch assembly may be a casing enclosing the claw and the first pawl such that the first pawl cannot be freely accessed. Preferably, the casing may also enclose the second pawl. According to a second aspect of the invention there is provided a motor vehicle door locking system comprising a number of door assemblies as provided in said - 3 - first aspect of the invention, a central control unit to control the movement of each first pawl, one or more input means each arranged to provide a signal to the central control unit indicative of a desired first pawl position, wherein the central control unit is operable to control latching and locking and of each of the door assemblies. Preferably each first pawl may be moveable by an electric motor controlled by the central control unit. The control unit may be arranged to move the first pawl of each door assembly in response to a signal received from a sensor operatively connected to a mechanical door release associated with the respective door assembly. The central control unit may be arranged to maintain the first pawl of one or more door assemblies in an engaged position irrespective of the movement of an associated door release. The invention will now be described by way of example with reference to the accompanying drawing in which:- Figure 1 shows a door assembly according to a first aspect of the invention; Figure 2 is a schematic diagram of a motor vehicle door locking system according to a second aspect of the invention; Figure 3 is a view in a direction of arrow "X" on Figure 1 showing a latch assembly forming part of the door assembly in a locked position; Figure 4 is a view similar to Figure 3 but showing the latch assembly in a released position; Figure 5 is a view similar to Figure 3 but showing the latch assembly in an unlocked but latched closed position; and - 4 - Figure 6 is a view similar to that of Figure 3 but showing an alternative embodiment of a latch assembly forming part of a door assembly in a locked position. With reference to Figures 1 to 5 there is shown a vehicle door assembly 10 having a door 4A with a latch mechanism 12 mounted on its rear edge. The latch mechanism 12 includes a latch lever 14 which is used to unlatch a mechanical door latch and a door release means in the form of interior and exterior door handles 16, 18. The interior and exterior door handles 16, 18 are connected to the latch lever 14 by respective finking means in the form of link rods 20, 22. The interior door handle 16 has a sensor in the form of a microswitch 6 associated therewith to sense motion of the door handle 16 in a door releasing direction. The microswitch 6 is connected by means of a cable 8 to a central electronic control unit 2. Each of the external door handles 18 similarly has the sensor in the form of a microswitch 30 associated therewith to send a signal to the electronic control 2 by means of a cable 28 to indicate when the door handle 18 is moved in a door release direction. The central control unit 2 is connected to a number of electric motors 5 forming part of a power operated actuator assembly used to move a first pawl 44 forming part of the latch assembly 12 between retaining and releasing positions. As shown in Figure 2, the motor vehicle has two front doors 4A, 4C and two rear doors 4B, 4D, each of said doors 4A, 4B, 4C, 4D forming in combination with an associated latch assembly and door assembly. With particular reference to Figures 3 and 5 the latch assembly comprises of a claw member 50 rotatably mounted by means of a spigot 60 upon a support in the form of a latch assembly housing 13, a first pawl 44 mounted upon the housing 13 and a second pawl 42 mounted upon the housing 13. The housing 13 encloses both the first and second pawls 44 and 42 and the claw 50 so that they cannot be tampered with. The first pawl 44 is movable from a retaining position as shown in Figure3 to a releasing position as shown in Figure 5 by means of the power actuator assembly. The power operated actuator assembly 32 comprises a motor 5 which drives through a gearbox 33 a drive shaft 36 used to rotate a worm gear 34. The worm gear 34 is drivingly engaged with a gear wheel 38 in which is mounted a drive pin 40. The drive pin 40 is engaged with a slot 39 formed in the first pawl 44 such that rotation of the gear wheel will cause the drive pin 40 to move the first pawl 44 into and out of engagement with the claw 50. The first pawl 44 is biased by a spring (not shown) into engagement with the claw 50. The claw 50 has a recess 58 used to accommodate a striker pin 52 attached to part of a door frame structure (not shown) and has first and second abutment surfaces 54, 56 for co-operation with an abutment surface 44A on one end of the first pawl 44 and further abutment surfaces 46, 48 for co-operation with an abutment surface 42A formed on one end of the second pawl 42. The second pawl 42 is moveable by means of the latch lever 14 between a first position in which abutment with the abutment surfaces 46 and 48 is possible to a - 6 - second position in which rotation of the claw 50 is unhindered by the second pawl 42. With particular reference to Figure 3 the latch assembly is shown in a door locking position in which the door is fully closed and secured in the closed position by engagement of the first pawl 44 with the abutment surface 56. The door assembly 10 cannot move in an opening or releasing direction as shown by arrow "R" on Figure3 because of the interaction of the striker pin 52 with the recess 58 and the engagement of the first pawl 44 with the abutment surface 56. Any motion in a door releasing direction "R" will cause the claw 50 to try and rotate in a counter clockwise direction. However, such movement is prevented by the abutment of the abutment surface 44A of the first pawl 44 with the abutment surface 56 on the claw 50. Therefore the door 10 is prevented from opening. It will be noticed on Figure 3 that the abutment surface 42A is not in contact with the abutment surface 48 on the claw 50 therefore the door 10 is being held closed only by the abutment of the first pawl 44 with the abutment surface 56. This is important as it means both latching and locking of the door 10 is obtained primarily by interengagement of the pawl 44 with the claw 50. The pawl 42 acting as a secondary latch only device which can be employed in certain circumstances as will be described hereinafter. Under normal circumstances the door is released in the following manner, operation of one of the door handles 16, 18 results in the associated microswitch 6, 30 being actuated. This sends a signal to the central control unit 2 which in response sends an energising signal to the respective electric motor 5 causing it to move the first pawl 44 out of engagement with the claw 50. The movement of the respective door handle 16, 18 results in the second pawl 42 being moved to a position in which it cannot become engaged with either of the abutment surfaces 46, 48 on the claw 50. The claw 50 is therefore free to rotate about the spigot 60 and movement of the door in an opening or release direction will result in the claw 50 rotating in a counter clockwise direction due to its interaction with the striker 52 until it adopts the position as shown in Figure4 in which the striker 52 is disengaged from the recess 58. The door 10 can then be opened freely from this position. The electronic control unit 2 is so arranged that after a pre-determined length of time, such as one second, it moves the first pawl 44 back into a position in which it could engage with the abutment surfaces 54, 56 on the claw 50. In fact the arrangement is such that the first pawl 44 is biased by the spring (not shown) towards the claw 50 such that the action of the power operated actuator 32 is merely to pull the pawl 44 out of engagement and to allow it to return under the action of the spring into engagement. Upon closing the door 4A, the claw 50 will initially engage the striker pin 52 as shown in Figure 4. Further closing movement of the door 4A from this position will cause a clockwise rotation of the claw 50 until it returns to the position as shown in Figure 3. If the door is not fully closed or does not close properly the claw 50 may not rotate sufficiently to allow engagement of the abutment surface 44A with the abutment surface 56 on the claw 50. In this circumstance the door 10 is prevented from opening by engagement of the pawl 44 with the abutment 54 rather than with the abutment surface 56. This is in order to ensure that an improperly secured door cannot inadvertently open and secondly to ensure that when the vehicle is locked the door is secured in a closed condition. The central control unit 2 may have one or more input means 3 associated therewith such as for example an infra red remote locking device. As described above in the unlocked state actuation of one of the door handles 16, 18 will result - 8 - in simultaneous movement of the first pawl 44 into a released position. However, when the central control unit 2 has received a signal from the input means 3 to lock the motor vehicle this is not the case and the first pawl 44 remains engaged with the claw 50 thereby maintaining all of the doors 4A, 4B, 4C, 4D in a locked condition. In this locked condition movement of any of the door handles 16, 18 will result in movement of the respective second pawl 42 but because of the engagement of the first pawl 44 with the claw 50, the door remains locked. In affect the central control unit 2 receives an instruction from the input means 3 to ignore any open signals received from the microswitches 6, 30 and so does not energise the respective electric motor 5 if a door handle 16, 18 is operated. When the input means 3 sends a signal to the central control unit 2 indicating that the doors 10 should be unlocked the outputs from the microswitches 6, 30 are re-enabled and any movement of one of the door handles 16, 18 will then once again result in simultaneous movement of the corresponding first pawl 44 out of engagement with its respective claw 50. In the event that the motor vehicle becomes involved in an accident the latch assembly 12 is placed into an intermediate latched condition in which the first pawl 44 is placed in a non-retaining position and maintained in that position until a reset signal is sent to the central control unit 2. In this state latching of each of the doors 10 is reliant solely on engagement of the abutment surface 42A with the abutment 48 on the claw 50. Therefore, in this situation, the doors 10 are held closed purely by the mechanically operated pawl 42 and so actuation of either of the door handles 16, 18 will result in mechanical unlatching of the respective door - 9 - This is achieved by providing the central control unit 2 with an input from a crash sensor 7 fitted to the motor vehicle This function is necessary to ensure that, in the event of an accident, the doors 10 are not maintained in an electrically latched position should the accident cause a loss of power to any of the motors 5 but are, by means of mechanical latching, retained in a closed position during and after the accident This situation is shown in Figure 5 in which the pawl 42 is engaged with the abutment surface 48 and the pawl 44 is moved out of engagement with the claw 50. If prior to an accident a door 10 is not fully closed it will still be maintained in the semi-closed position by interaction of the pawl 42 with the second abutment surface 46 which acts as a secondary or safety latching position. It will be appreciated that the independent connection of each of the electric motors 5 to the central control unit 2 allows many possibilities. The central control unit 2 for example can be so programmed that upon receiving an unlock signal from the input means 3 only door 4A is unlocked the remaining doors 4B, 4C and 4D remaining m a locked state with the first pawls 44 engaged with the respective claws 50. In this case a secondary input means (not shown) would be provided within the confines of the motor vehicle to unlock the remaining doors 4B, 4C and 4D. The advantage of such a system is that a driver can obtain access to the motor vehicle without risking opening other doors which may allow a potential criminal from entering the vehicle. The input means 3 could be one or more switches arranged on a dashboard of the vehicle which when actuated isolate the microswitches 6 associated with the - 10 - interior door handle 16 on door assemblies 4B and 4D. This provides a convenient and simple way of providing child proof locking to the rear doors 4B and 4D such that these doors cannot be unlatched from inside the vehicle. Turning to Figure 6 there is shown an alternative embodiment of a latch assembly for use with the present invention. The latch assembly will be understood to be suitable for use with the vehicle door assembly of the previous embodiment. The latch assembly comprises a claw member 150 rotatably mounted by means of a spigot 160 upon a support in the form of a latch assembly housing 113, a first pawl 144 mounted upon the housing 113 and a second pawl 142 mounted upon the housing 113. The first pawl 144 and the second pawl 142 are mounted for rotation about a common spigot 170. A wall provided about a periphery of the housing 113 encloses both the first and second pawls 144 and 142 and the claw 150 so that they cannot be tampered with. The first pawl 144 is movable from a retaining position as shown in Figure 6 to a releasing position by means of a power actuator assembly 132. The power operated actuator assembly 132 comprises a motor 105 which drives through a gearbox a drive shaft used to rotate a worm gear 134. The worm gear 134 is drivingly engaged with a gear wheel 138 in which is mounted a drive pin 140. The drive pin 140 is engaged with a shaped opening 139 formed in the first pawl 144 such that rotation of the gear wheel will cause the drive pin 140 to move the first pawl 144 into and out of engagement with the claw 150. The first pawl 144 may be biased by a spring (not shown) into engagement with the claw 150. - 11 - The claw 150 has a recess 158 used to accommodate a striker pin 152 attached to part of a door frame structure (not shown) and has first and second abutment surfaces 154,156 for co-operation with an abutment surface 144A on one end of the first pawl 144 and also an abutment surface 142A on one end of the second pawl 142. The second pawl 142 is moveable between as first position in which abutment with the abutment surfaces 154,156 is possible to a second position in which rotation of the claw 150 is unhindered by the second pawl 142. With particular reference to Figure 6 the latch assembly is shown in a door locking position in which the door is fully closed and secured in the closed position by engagement of the first pawl 144 with an abutment surface 156. The door assembly cannot move in an opening or releasing direction because of the engagement of the first pawl 144 with the abutment surface 156. Any motion in a door releasing direction "R" will cause the claw 150 to try and rotate in a counter clockwise direction. However, such movement is prevented by the abutment of an abutment surface 144A of the first pawl 144 with the abutment surface 156 on the claw 150. Therefore the door is prevented from opening. It will be noticed on Figure 6 that an abutment surface 142A is not in contact with the abutment surface 156 on the claw 150 therefore the door is being held closed only by the abutment of the first pawl 144 with the abutment surface 156. This means both latching and locking of the door is obtained primarily by interengagement of the pawl 144 with the claw 150. The pawl 142 acting as a secondary latch only device which can be employed in certain circumstances as will be described hereinafter. - 12 - Under normal circumstances the door is released in the following manner, operation of one of the door handles results in an associated microswitch being actuated. This sends a signal to a central control unit which in response sends an energising signal to a respective electric motor 105 causing it to move the first pawl 144 out of engagement with the claw 150. The movement of the respective door handle results in the second pawl 142 being moved to a position in which it cannot become engaged with either of the abutment surfaces 154,156 on the claw 150. The claw 150 is therefore free to rotate about the spigot 160 and movement of the door in an opening or release direction will result in the claw 150 rotating in a counter clockwise direction due to its interaction with the striker pin 152 until it adopts __a position in which the striker pin 152 is disengaged from the recess 158. The door can then be opened freely from this position. The electronic control unit is so arranged that after a pre-determined length of time, such as one second, it moves the first pawl 144 back into a position in which it could engage with the abutment surfaces 154,156 on the claw 150. In fact the arrangement is such that the first pawl 144 may be biased by a spring (not shown) towards the claw 150. The action of the power operated actuator 132 is merely to pull the pawl 144 out of engagement and to allow it to return under the action of the spring into engagement. The spring (not shown) is disposed in an over centre arrangement. Thus, after the first pawl 144 has been pulled out of engagement by the power operated actuator, the first pawl remains disengaged and is not biased by the spring towards the claw 150, until the first pawl has been returned by the power operated actuator to engagement with the claw 150. Upon closing the door, the claw 150 will initially engage the striker pin 152. Further closing movement of the door will cause a clockwise rotation of the claw 150 until it returns to the position as shown- in Figure 6. If the door is not fully closed or does not close properly the claw 150 may not rotate sufficiently to allow - 13 - engagement of the abutment surface 144A with the abutment surface 156 on the claw 150. In this circumstance the door is prevented from opening by engagement of the pawl 144 with the abutment surface 154 rather than the abutment surface 156. This is in order to ensure that an improperly secured door cannot inadvertently open and secondly to ensure that when the vehicle is locked the door is secured in a closed condition. The central control unit may have one or more input means associated therewith such as for example an infra red remote locking device. As described above in the unlocked state actuation of one of the door handles will result in simultaneous movement of the first pawl 144 into a released position. However, when the central control unit has received a signal from the input means to lock the motor vehicle this is not the case and the first pawl 144 remains engaged with the claw 150 thereby maintaining all of the doors in a locked condition. In this locked condition movement of any of the door handles will result in movement of the respective second pawl 142 but because of the engagement of the first pawl 144 with the claw 150, the door remains locked. In effect the central control unit receives an instruction from the input means to ignore any open signals received from the microswitches and so does not energise the respective electric motor 105 if a door handle is operated. When the input means sends a signal to the central control unit indicating that the doors should be unlocked the outputs from the microswitches are re- enabled and any movement of one of the door handles will then once again result in simultaneous movement of the corresponding first pawl 144 out of engagement with its respective claw 150. - 14 - In the event that the motor vehicle becomes involved in an accident the latch assembly is placed into an intermediate latched condition in which the first pawl 144 is placed in a non-retaining position and maintained in that position until a reset signal is sent to the central control unit. In this state latching of each of the doors is rehant solely on engagement of the abutment surface 142A with the abutment surface 156 on the claw 150. Therefore, in this situation, the doors are held closed purely by the mechanically operated pawl 142 and so actuation of either of the door handles will result in mechanical unlatching of the respective door. This is achieved by providing the central control unit with an input from a crash sensor fitted to the motor vehicle. This function is necessary to ensure that, in the event of an accident, the doors are not maintained in an electrically latched position should the accident cause a loss of power to any of the motors 105 but are, by means of mechanical latching, retained in a closed position during and after the accident. In this situation the pawl 142 is engaged with the abutment surface 156 and the pawl 144 is moved out of engagement with the claw 150. If prior to an accident a door is not fully closed it will still be maintained in the semi-closed position by interaction of the pawl 142 with the second abutment surface 154 which acts as a secondary or safety latching position. It will be appreciated that the independent connection of each of the electric motors 105 to the central control unit allows many possibilities. The central control unit for example can be so programmed that upon receiving an unlock signal from the input means only one door is unlocked the - 15 - remaining doors remaining in a locked state with the first pawls 144 engaged with the respective claws 150. In this case a secondary input means (not shown) would be provided within the confines of the motor vehicle to unlock the remaining doors. The advantage of such a system is that a driver can obtain access to the motor vehicle without risking opening other doors which may allow a potential criminal from entering the vehicle. The input means could be one or more switches arranged on a dashboard of the vehicle which when actuated isolate the microswitches associated with the interior door handle on, for example, the rear door assemblies. This provides a convenient and simple way of providing child proof locking to the rear doors such that these doors cannot be unlatched from inside the vehicle.

Claims: - 16 - CLAIMS 1. A door assembly for a motor vehicle door comprising a door structure and a latch assembly to maintain the door in a closed position, the latch assembly comprising a support member for attachment to part of the door structure to be secured, a claw member pivotally mounted upon said support for movement between a door latching position and a door release position, a first pawl to hold said claw in said door latching position, a second claw engageable with the claw as a secondary latching means and an power operated actuator to move said first pawl out of engagement with the claw. 2. _ A door assembly according to Claim 1, characterised in that the power operated actuator is an electric motor. 3. A door assembly according to Claim 2, characterised in that the electric motor is connected to the first pawl by a worm and gear drive. 4. A door assembly according to any previous claim, characterised in that after release of the first pawl the second pawl prevents the claw from rotating from the door latching position until it is released. 5. A door assembly according to any of Claims 1 to 3, characterised in that the door assembly further comprises at least one door release connected by a mechanical linkage to the second pawl to move it to a claw releasing position. 6. A door assembly according to Claim 5, characterised in that the or each door release has a sensor associated therewith to provide an output signal when the door release is operated. - 17 - 7. A door assembly according p any previous claim, characterised in that the claw has a recess for co-operation with a striker attached to part of the body structure of the motor vehicle to provide a means for holding the door in a latched position, the claw being rotatable from the door latching position characterised in that the striker is trapped in the recess to the door releasing position characterised in that the striker can enter or exit the recess when the door is removed. 8. A door assembly according to any previous claim, characterised in that at least one of the pawls is engageable with the claw to hold it in a part latched position characterised in that the door is prevented from opening but is not held fully closed. 9. A door assembly according to Claim 8, characterised in that both of the pawls are engageable with the claw to hold it in a part latched position. 10. A door assembly according to any previous Claim, characterised in that the support member for the latch assembly is a casing enclosing the claw and the first pawl such that the first pawl cannot be freely accessed. 11. A door assembly according to Claim 10, characterised in that the casing also encloses the second pawl. 12. A door assembly according to any previous claim, characterised in that the first pawl and the second pawl are mounted for rotation about a common spigot. 13. A motor vehicle door locking system comprising a number of door assemblies according to any of claims 1 to 12, a central control unit to control the movement of each first pawl, one or more input means each arranged to - 18 - provide a signal to the central control unit indicative of a desired first pawl position wherein the central control unit is operable to control latching and locking of each of the door assembhes. 14. A motor vehicle door locking system according to Claim 13, characterised in that each first pawl is moveable by an electric motor controlled by the central control unit. 15. A motor vehicle door locking system according to either Claim 13 or Claim 14, characterised in that the control unit is arranged to move the first pawl of each door assembly in response to a signal received from a sensor operatively connected to a mechanical door release associated with the respective door assembly. 16. A motor vehicle door locking system according to either Claim 13 or Claim 14, characterised in that the central control unit is arranged to maintain the first pawl of one or more door assembhes in an engaged position irrespective of the movement of an associated door release. 17. A door assembly for a motor vehicle door substantially as described herein with reference to any of the accompanying drawings. 18. A motor vehicle door locking system substantially as described herein with reference to any of the accompanying drawings.

Inventors: NICHOLLS STEPHEN PAUL, NICHOLLS, STEPHEN, PAUL
Applicants: NICHOLLS STEPHEN PAUL, ROVER GROUP, NICHOLLS, STEPHEN, PAUL, ROVER GROUP LIMITED
Application year: 1999
Main classification: E05B47
IPC codes: E05B65