This section provides background information related to the present disclosure and which is not necessarily prior art.
In the following description and the accompanying claims, the expression “door” will be used to generally indicate any element movable between an open position and a closed position, respectively opening and closing an access to an inner compartment of a motor vehicle, and therefore including boot, rear hatches, liftgates, bonnet lid or other closed compartments, in addition to the side doors of the motor vehicle, to which the following description will make explicit reference.
As it is known, door latches are provided in motor vehicles for controlling opening and closing of the side doors (driver and passenger doors, and rear doors if present). Such a door latch generally includes a latch mechanism having a ratchet that is selectively rotatable with respect to a striker fixed to a door post in order to latch and unlatch the door. The ratchet is typically moveable between a striker capture position whereat the door is latched and a striker release position whereat the door is unlatched. The latch mechanism also typically includes a pawl that is operable in an engaged or ratchet holding position to engage the ratchet and prevent the ratchet from rotating out of its striker capture position.
In traditional arrangements, the pawl is moved from its engaged position to a non-engaged or ratchet releasing position which, in turn, permits the ratchet to rotate to its striker release position. Typically, the pawl is moved to its non-engaged position via a manual actuation of a mechanical element such as, for example, a release lever that is mechanically interconnected via a linkage mechanism to a door handle. Electrical door latches may instead include an electric motor, which is electrically connected to a main electric power supply of the vehicle (e.g. to the 12 V battery of the same vehicle), in order to directly or indirectly drive the pawl to its non-engaged position via an electrically-operated actuator (e.g. including a release lever) so as to release or unlock the latch after receiving a user command issued, for example, via a remote electronic key.
Number 1 in FIG. 1 indicates, as a whole, an electrical latch assembly 1 that is coupled to a side door 2 of a motor vehicle 3.
Electrical latch assembly 1 is electrically connected to a main power source 4 of motor vehicle 3 (i.e. a main battery providing a battery voltage Vbatt of 12 V) through an electrical connection element 5 (i.e. a power cable). Alternatively, main power source 4 may equally include a different source of electrical energy within motor vehicle 3 such as, for example, an alternator.
Electrical latch assembly 1 includes an actuation group 6′ including in this case an electric motor 9 operable to control latching and unlatching of side door 2. In a possible embodiment, actuation group 6′ also includes a latch mechanism having a ratchet 6 and a pawl 8. Ratchet 6 is selectively rotatable to engage a striker 7 that is fixed to the body of motor vehicle 3 (e.g. to the so called “A pillar” or “B pillar”) in a manner not shown in detail. When ratchet 6 is rotated into a latching or striker capture position with respect to striker 7, side door 2 is in a closed (i.e. latched) operating state. Pawl 8 selectively engages ratchet 7 in an engaged or ratchet holding position to prevent it from rotating out of the striker capture position. Paul 8 is moveable between the engaged position and a non-engaged or ratchet releasing position for permitting ratchet 6 to move from its latching position into an unlatching or striker release position. When ratchet 6 is located in its unlatching position relative to striker 7, side door 2 is in an opened (i.e. unlatched) operating state.
In some solutions, electrical latch assembly 1 may further include an electronic control circuit 10 (e.g. including a microcontroller or other known computing unit) which may be conveniently integrated and arranged in a common housing or case 11 (shown schematically) with actuation group 6′, thus providing a compact and easy-to-assemble unit.
Electronic control circuit 10 is in this case coupled to the electric motor 9 and provides driving signals Sd thereto in order to control latch operation. Electronic control circuit 10 is electrically coupled via a data bus 14 to a vehicle main management unit (also known as main ECU or “vehicle body computer”) 12 which is configured to control general operation of motor vehicle 3 so as to exchange signals, data, commands and/or information.
Electronic control circuit 10 is also coupled to main power source 4 of motor vehicle 3 so as to receive the battery voltage Vbatt, and may also include an embedded and integrated backup energy source (here not shown) which is configured to supply electrical energy to actuation group 6′ and electric motor 9, as well as to electronic control circuit 10, in case of failure or interruption of the main power supply from main power source 4 of motor vehicle 3.
It is known that security regulations require the possibility of controlling opening and closing of the doors even in case of failure or discharge of the main power supply of the vehicle, in case of interruptions or breaking of the electrical connection between the main power supply and the electric motor in the latch, or in case of malfunctions of the same electric motor. In other words, a latch release backup system must be provided.
Known release backup systems typically include a mechanical key cylinder 15 housed in vehicle door 2 and configured to receive a mechanical key of the vehicle for releasing or unlocking the latch mechanism, namely for moving pawl 8 to its non-engaged position via a mechanical connection element 16 (in a known manner, here not discussed in detail). This mechanical key and key cylinder arrangement operates as a manual backup to the electrically-activated door latch mechanism. As is conventional, key cylinder 15 is mechanically paired to the vehicle key and carries a suitable mechanical code to match with the key and interact therewith (in a known manner, here not discussed in detail).
However, the presence of this mechanical arrangement entails a high area occupation and weight and additional costs, and also represents a constraint for designing the vehicle door in terms of door style design, or standardization of door and handles between passenger and driver sides or among different vehicles. Moreover, the presence of mechanical key cylinder 15 entails possible security issues, since it may not be difficult for a thief to exploit and gain access to the related mechanism in order to access the vehicle. Suitable anti-theft devices have therefore to be envisaged, again with consequences on the complexity and overall costs of the system.
A need is therefore felt for an improved latch release backup system for a motor vehicle latch.