The invention relates to a latch unit for a door or tailgate, especially for a motor vehicle, with a lock comprising a locking mechanism consisting of a catch and at least one pawl for engaging the catch, and a drive unit built as cinching aid, by which the locking mechanism can be moved in a way that the door or tailgate moves towards the car body against the resistance of the door seal . For identifying the lock positions it is intended to use control devices comprising one catch sensor and one pawl sensor as well as a control logic activated by these two sensors .

A lock of a latch u nit as described a bove is used for temporarily locking apertures in vehicles or buildings by means of doors or tailgates. If such a lock is in locked position the catch with two arms ( load arm and work arm) grabs arou nd an often bracket-shaped locking bolt. I n a motor vehicle this bolt ca n be mounted to a door or tailgate with the lock being mou nted to the car body, or vice- versa . For motor vehicles in particular, there are side door locks, tailgate locks, a nd bonnet locks. The present invention is advantageously designed for locks for vehicle tailgates. Such tailgates, also named boot lids, normally are at the rear end of a vehicle.

The lock of the invention is normally body-side mounted, in other words it is mounted to the respective car body. The locking bolt, on the opposite, is mounted to the door or tailgate. However, the arrangement can also be vice-versa .

If in such a lock the catch of the locking mecha nism travels from opened position to locked position when the respective door or tailgate is swiveled, the catch will be engaged by the pawl. Such swiveling is caused by the locking bolt (also named striker or bolt catch) dropping into the catch when the respective door or tailgate is closed. This position of the lock is called primary position ( P P) .

Locking mechanisms for motor vehicles normally have two lock positions, that is the already mentioned primary position ( P P) and a so-called secondary position (SP ) . The secondary position (S P ) serves to hold the respective door if, i.e. the locking mechanism does not reach primary position , and thus, even if the locking process does not work properly, at any rate prevents uncontrolled opening of the door.

To open the lock, the pawl must be lifted from locked position . If the pawl is lifted from locked position by means of an opening device, i.e. a pull handle, the spring-loaded catch turns towards open position. With the catch and thus the locking mecha nism being in open position the locking bolt can move out of the lock, and the door or tailgate can be opened again .

Such a lock can comprise an electric drive unit for moving the locking mechanism from secondary position (SP) to primary position ( PP) and finally locking it in primary position ( PP) . Such a loc k is also called cinching lock, closing aid or servo lock and is known from D E 1 0 2009 026 921 A l .

DE 1 0 2008 005 1 81 A l describes a cinching aid/closing aid for pulling a tailgate or vehicle door towards the car body against the resistance of the door seal . The here described drive unit is also used to open the door or tailgate. Combined pulling close a nd electrical opening of a tailgate lock is described in the prints D E 1 0 2004 01 1 798 B3 as well as DE 1 0 2004 01 3 671 A l . For opening a lock an operation device is needed . If this device is activated, the locking mechanism of the lock will open . A door or tailgate handle can be part of such an operation device. Such a handle is normally connected to an operating and/or triggering lever via a rod system or a Bowden cable. When the handle is operated, the rod system or Bowden cable swivels the operating and/or triggering lever of the lock in a way that the pawl is lifted from the catch and the lock is opened under the load of a spring . Motor vehicles normally have a pivoting outer handle, which can be operated from outside, and/or a usually pivoting inner handle, which can be operated from inside the car.

In practice, locking and opening devices are used which generally provide that when a certain pre-lock position (secondary position ) is reached the respective door or tailgate is moved towards the car body against the resistance of the door seal by the motor driven locking mechanism, and will be pressed against the car body thus reaching primary or closed position . Apart from that, opening devices are known which open or hold open the respective door or tailgate away from the car body. Principally, such locking/opening devices can also be combined with one another.

All in all, for such latch units certain controlling mea ns (control devices) are needed . Such devices are a mongst others mechanical or optical sensors as well as processing units used for control which are activated by the sensors, so-called control units or control logics.

According to the state of the art there are latch units with cinching/closing aids with control logics fed by three sensor elements. One sensor is mounted to the respective door or tailgate in order to record the positions "open " or "closed" . The two other sensors are assigned one to the catch a nd one to the pawl each, in order to record the respective positions of the catch and the pawl . I n total the control logic receives signals from three different control positions. With the help of these sensors, the door/lock positions are detected - open (I ) , secondary position (I I ) and primary position (V) - a nd processed by the control unit accordingly.

From WO 1 999/ 491 59 A l the state of the art knows a com bined locking/opening device with a respective door or tailgate being motor-driven from secondary to primary position . Ca bling and shifting is simplified and based on two sensors only, with the sensor signals being processed by a respective control unit. Here, too, the door and lock positions open (I ) , secondary position ( I I ) a nd primary position (V) are identified and respectively processed by the control unit.

A drive unit for a cinching aid for example is known from DE 1 0 2009 036 834 A l . It is important for such motor-driven latch units that the locking process runs perfectly. A perfectly running locking process secures that in a possible car crash the full tear resistance of the locking mechanism is provided, a nd thus an opening of the door or tailgate is prevented without fail .

This means, even if the door or tailgate is moved with another than the normal operating force, the perfect run of the locking process must be guaranteed, for example if the door is closed with too much force and therefrom resulting high velocity. On the other hand, it happens that the respective door or tailgate is operated with low force and low velocity only. I n this case the door or tailgate is left ajar or inserted into the locking mechanism. Environmental conditions, too, like ice or snow covering the door seals, might influence the closing process.

Such operations different from the normal door a nd tailgate locking operation are named slamming of a door or tailgate or leaving the door or tailgate ajar. If the respective door or tailgate is slammed with high force into the lock a nd consequently hits the lock with high impact, the cinching force of the drive unit is not needed as the momentum normally moves the locking bolt inserting into the catch mouth into primary position or overtravel position respectively, and therewith into locked position . At any rate is must be secured that the cinching aid starting to operate during the locking process is set back to starting position to be ready for the next locking process. Further, it must be secured that, if centrifugal forces cause the door or tailgate to rebound after heavy slam ming, the cinching drive starts working immediately in order to grant proper locking of the locking mechanism . Furthermore, with a ny locking speed a nd in any position u ntil reaching primary position it must be secured that the cinching aid starts operating a nd completes operation. Finally, whenever the respective door or tailgate is operated the secure locking of the lock equipped with a cinching aid must be guaranteed .

The already mentioned state of the art known from WO 1 999 / 49 1 59 A l describes the arrangement of two sensors interacting with a control logic for controlling such a lock equipped with a cinching aid, especially for identifying the position of the respective door or tailgate.

I n order to exactly identify the position of the catch one sensor is assigned to the catch, to identify secondary position or primary position of the pawl the other sensor is assigned to the pawl . Thus, to operate the cinching aid of this lock, two sensors only, one catch sensor and one pawl sensor, are sending signals to the control logic. From the combination of these signals the following lock positions are detected to operate the cinching aid:

The main objective of the invention is to further optimize a generic lock with regard to handability and security.

It is one objective of the invention to provide a convenient latch unit, designed of few parts only and equipped with a simple control system and an optimized cinching aid, which guarantees safe pulling close and locking of the respective door or tailgate at any time during the closing process and under extreme operating and environmental conditions, too.

These objectives are solved by a latch unit according to claim 1. Advantageous embodiments result from the dependent claims.

A latch unit for a door or tailgate, especially for a motor vehicle, with a lock comprising a locking mechanism consisting of a catch and at least one pawl for arresting the catch, and a drive unit built as cinching aid, by which the locking mechanism can be moved in a way that the door or tailgate moves towards the car body against the resistance of the door seal. For identifying the lock positions open, secondary position, primary position, it is intended to use control devices comprising one catch sensor and one pawl sensor as well as a control logic activated by these sensors for controlling the cinching aid . According to the invention for controlling the cinching aid via the controlling devices at least one further lock position can be detected .

I n the context of the invention controlling the cinching aid in the first place means triggering the drive unit to start the pulling close process. Lock positions in the context of the invention may also mean ranges (sections) of positions .

This embodiment of a latch unit with cinching aid with at least one further lock position to be detected for control guarantees secure engagement of the locking mechanism, even u nder extreme operating a nd conditions like extreme closing velocity, without installing any further parts, and without installing any additional or costly control devices. I mportant is the advantageous selection of the additional lock positions and a well targeted switching logic.

I n a first embodiment of the latch u nit it is intended that the control devices detect a position between secondary a nd primary position as additional lock position .

This embodiment of the latch u nit secures that any lock positions and therewith positions of the locking mechanism between the starting position of the cinching drive unit in secondary position and the end stop in primary position are detected and that there will not be any position of the locking mechanism not covered by the cinching aid. When the end stop primary position is reached the locking mechanism normally slightly overtravels the primary position in order to secure that the pawl engages safely. This overtravel range of the locking mechanism is normally 1 - 3 mm . That means the invention does not exclude that the cinching aid is started when primary position is reached.

I n a preferred embodiment of the latch unit it is intended that a further lock position located between lock secondary position a nd lock primary position can be detected which is the range between where the catch leaves secondary position in locking direction and where the pawl leaves secondary position of the catch .

Selection of this sensitive range of the locking mechanism considerably increases the security of the lock, as with the door or tailgate being left ajar as a result from low-velocity closing, it is not necessarily granted that the starting position of the drive unit is reached . However, it is achieved to detect this range by means of a suitable control logic with the already existing control devices. The range covers the narrow part of the secondary position stop (secondary position tooth) , which in general (quasi) runs radial to the catch rotation axis, in front of where the pawl sinks back on the rim of the catch during the closing process.

I n a further preferred embodiment of the invention a further lock position is detected by means of the control devices, which is located between the lock secondary position and the lock primary position, in the range between the pawl leaving secondary position (secondary position tooth) and reaching the primary position of the lock.

This embodiment of the invention achieves, that any positions of the locking mechanism, initiated i.e. by extreme closing velocity, between the actual starting point of the cinching aid (secondary position) a nd the target point (primary- and locked position ) are identified by the control devices, and the door or tailgate will be im mediately moved into closing position via the control logic activated by two sensors only, thus enabling safe engagement of the locking mecha nism in primary position .

In a further preferred embodiment of the invention the respective positions of the lock are identified by a catch sensor interacting with a control contour located on the catch surface ( mea ning one of the side surfaces) .

This embodiment of the invention with a special geometry of the control contour is a very important part of the invention . The contour, which will later be explained in detail, has been designed considering that all positions of the locking mechanism have to be detected . The contour on one ha nd allows for a switch position to safely detect the starting point of the cinching aid in secondary position, and on the other hand allows for immediately changing the position of the switch in order to safely detect when the locking mechanism is in the range of the secondary position . The contour as desig ned is a significant prerequisite for that the complete range of the locking mechanism between secondary and primary position can be detected with only two synchronized sensors as control devices. With the knee-formed range (point) in the contour two adjacent ranges can be detected during rotation of the catch .

I n a special preferred embodiment of the invention the catch sensor in catch open position shows an initial bevel in counter clockwise direction relative to the horizontal in the range of 35° to 45°, preferably 40°, and a final bevel, connected to a transition range in form of a knee-formed ra nge ( point) , of 90° to 1 00°, preferably 95°. This special embodiment of the control contour of the catch sensor with the transition range allows for seamlessly detecting two adjacent lock positions. The transition ra nge prefera bly desig ned as knee-formed range or point shows when the loc k leaves secondary position . Com pared to the pawl the catch is designed by the contour with the knee-formed transition range as dyna mic control position which works when the catch is rotating. All positions of the lock following the secondary position as first position can be safely detected by the catch sensor interacting with the pawl sensor, for starting the cinching drive.

I n a further embodiment of the latch unit the lock positions are detected by the pawl sensor as control device interacting with a control stop on the pawl.

This em bodiment of the invention in which the pawl sensor interacts with the fixed stop on the pawl is, contrary to the catch , designed as static control device and secures the detection of the stops secondary position and primary position and with the thus created control logic allows for secure operation of the lock according to the invention .

I n a further special embodiment of the invention the lock positions are identified by sensors in form of mechanical, magnetic or optical sensors, like micro-switches, Reed-contacts or H all sensors, with the mecha nical identification by means of micro-switches being especially advantageous.

In a special embodiment of the invention the sensor signals released from the sensors shall be recognized by the control logic as follows: Lock position "open", if the catch sensor reacts, the pawl sensor does not react (signals sensor catch 4 / sensor pawl 5 (1/0).

II. Lock position "secondary position", if both sensors react (signal 1 /I ).

III. Lock position after leaving secondary position, if the catch sensor does not respond, and the pawl sensor responds (signal 0/1 ).

Lock position between leaving secondary position and before reaching primary position, if both sensors do not respond (signal 0/0).

Lock position ..primary position", if the catch sensor does not respond, the pawl sensor responds (signal 0/1).

This results in the following schematic:

catch means signal switch position catch sensor

pawl means signal switch position pawl sensor

* "primary position" includes the described travelling of the locking mechanism into the so-called overtravel range of the lock. With the described signal switch positions all relevant data for safe detection of all positions (ranges) , also those between secondary position and primary position, are sent to the control unit.

I n a special embodiment of the latch unit the drive unit for the cinching aid is started when the control logic identifies the control sig nals according to ranges I I, I II , IV or V of the locking mecha nism .

It is evident that the drive unit after having started in one of the respective positions / ranges of the locking mechanism runs up to the above mentioned overtravel range and thus allows for secure locking close in primary position . I n overtravel range the drive unit runs on block operation, this abruptly increasing the power consu mption of the drive unit. As a result, the drive unit reverses to starting position and prepares for the next cinching operation .

I n the context of the invention it is evident that the latch unit also includes an anti-trap protection . This anti-trap protection will be activated if the pulling close operation is interru pted by an object (obstacle) in the area between door or tailgate and car body. The increased current consumption caused by the resistance makes the control unit im mediately change the drive unit to reverse operation .

A control logic designed in this way provides an easy-to-handle latch unit with cinching aid which also considers a bnormal closing velocities, and which is equipped with a simply designed control logic with two control sensors only, a nd guarantees safe pulling close and locking of the respective door or tailgate from different positions of the locking mechanism . If not indicated differently, the object of the invention can include each of the above mentioned characteristics individually or the characteristics in any combination.

An advantageous embodiment of a latch unit according to the invention is illustrated in the following figures:

Figure 1 : Plan view of the lock in "open" position

Figure 2: Lock in "secondary position"

Figure 2a: "Secondary position", enlarged

Figure 3: Lock in the position after leaving "secondary position"

Figure 3a: After leaving "secondary position", enlarged

Figure 4: Lock in the position in the range between "secondary position" and "primary position"

Figure 4a: Lock in the position in the range between "secondary position" and „primary position, enlarged

Figure 5: Lock in "primary position"

Figure 5a: Lock in "primary position", enlarged

Figure 6: Graph and table with sensor switch diagram

Figure 1 illustrates the assembly with all essential parts of a latch unit 10 with a cinching aid 6 according to the invention for a here invisible vehicle door or tailgate. The lock 10 is shown in plan view without the lock cover. The lock 10 consists of a locking mechanism

I 2 comprising a catch 1 and a pawl 2 as well as a rod 9 connecting the catch 1 to the drive unit 6 of the cinching aid 6. Bearing of the locking mechanisml 2 is realized inside the lock housing 11. Bearing of the catch 1 is realized by the catch rotation axis 1.1 , bearing of the pawl 2 by the pawl rotation axis 2.1. The lock housing

I I can also be designed as lock plate 11. As connecting element 9 to the drive unit of the cinching aid alternatively a Bowden cable 9 can be used. In the illustrated example the drive unit 6 of the cinching aid 6 is mounted outside the lock 10 and is drawn as a box 6 only. It is intended that during the pulling close process the drive unit 6 moves the locking mechanism 1 2 consisting of catch 1 and pawl 2 from lock position "secondary position" II to lock position "primary position" V and thus pulls the lock into closed position V against the resistance of the door seal. The drive unit 6 amongst other comprises an electric motor, an actuator, a drift shaft, and a gear unit. A preferably used drive unit is known from DE 102009036 834 Al . However, the invention is not restricted to such a drive unit.

When the respective door or tailgate is closed the locking bolt 3 mounted to the tailgate runs into the mouth 1.2 of the catch 1, which is built by the load arm 1.3 and the work arm 1.4. Therewith, the catch 1 will be pivoted in closing direction as marked by the arrow. With the help of the pawl 2 the locking mechanism 1 2 can be engaged in secondary position SP (II) and in primary position PP (V) of the catch 1. For opening an engaged locking mechanism 1 2 the pawl 2 Is lifted via a mechanical operation lever (door handle, not shown) preferably mounted to the car body, with the spring loaded catch 1 then swiveling from primary position PP V to open position I.

The lock housing 11 of the latch unit 10 is mounted to, preferably screwed to, the car body via screw holes 12 13. For better stability the lock housing 11 is preferably made of metal. Catch 1 and pawl 2 are equally completely or in parts made of metal.

To control the drive unit 6 of the cinching aid 6 the respective positions of the catch 1 and the pawl 2 are detected via the catch sensor 4 and the pawl sensor 5 respectively. The signals from the sensors 45 will then be sent to the control unit 7 which in figure 1 is illustrated as a box only. Sensors 45 are shown without any fixing elements. Normally, the control unit 7 is arranged a bove the locking mecha nism 1 2 inside the lock housing 1 1 . But the control unit 7, as illustrated here, can also be mounted outside of the lock 1 0. The necessary electrical connections between the control elements 4 5 7 and from the control elements 4 5 7 to the drive unit 6 are not shown .

I n the example illustrated in figure 1 the sensors 4 5 are both designed as micro switches. However, comparable devices like for exa mple Hall sensors can also be used to detect the lock positions I II I I I IV V. Sensor 4 of the catch interacts with a control contour 1 .6 on the catch side surface 1 .5. Sensor 5 for the pawl 2 is working on a pawl sensor stop 2.2 on the pawl 2.

Figure 1 shows the locking mechanism consisting of catch 1 a nd pawl 2 in open position I , i.e. the related door or tailgate is also open .

According to the switch diagram in figure 6 the lock is in open position I, with the sensor 4 of the catch 1 engaging with the catch sensor contour 1 .6 at the initial bevel of the contour 1 .7. I n this position the sensor sends the signal 1 for " open" . Sensor 5 of the pawl 2 is outside the pawl sensor stop 2.2 and consequently sends the signal 0, as the pawl 2 is outside and not engaged .

The overall control contour 1 .6 consists of the initial bevel contour 1 .7 with the adjacent transition contour 1 .8 and the final bevel contour 1 .9. Preferably the initial bevel contour 1 .7 - related to the catch 1 in open position - with an initial length of 1 5 mm ru ns anticlockwise at an angle of 35° to 45° related to the horizontal . An angle of 40° is especially preferred . The final bevel contour with a length of 1 0 mm runs at an angle of 90° to 1 00°, especially preferred 95°, related to the horizontal. Based on the thus created control contour 1 .7 sensor 4, as later on explained in detail, is working as dynamic switch 4.

The latch u nit 1 0 as illustrated is designed for being mounted to a vehicle tailgate or boot lid preferably in driving direction at the rear end of the vehicle. When opened, such tailgates are swiveled towards the car body. The latch unit 1 0 with a lock housing 1 1 normally is mounted to the front rim of the tailgate closing the boot.

I n figure 2, for a good overall view, the drive unit 6, the connection rod 9, and the control unit 7 have been omitted . For locking the respective door or tailgate the here also invisible locking bolt 3 has been inserted into the mouth 1 .2 of the catch 1 . Locking is normally done by ha nd . The locking bolt 3 abuts on the load arm 1 .3 of the catch 1 triggering the catch 1 in clockwise direction against the spring effect of a here invisible spiral spring . I n figure 2 the catch 1 has been swiveled so far in the direction of the arrow that the catch 1 has reached the lock position II , secondary position SP . I n this position I I the pawl 2 spring-loaded against the catch 1 is equally moved in clockwise direction and engages into secondary position SP of the catch according to Figure 2a, which shows a background segment of pawl 1 enlarged.

According to the switch diagram of figure 6 the lock now is in secondary position I I . I n this position II the sensor 4 of the catch 1 is located at the end of the now nearly horizontal initial bevel 1 .7 of the control contour 1 .6. Consequently, it sends the sig nal 1 for secondary position I I. Pawl 2 has engaged in secondary position I I with the pawl-sensor stop 2.2 running into sensor 5, causing sensor 5 of the pawl 2 to also send the signal 1 . The signal switch position catch 1 / pawl 1 shows the secondary position I I of the locking mechanism 1 2, with the here invisible drive unit 6 with the cinching aid 6 being started via the con trol unit 7 with the aim to move the locking mechanism 1 2 towards closed position and engage it in this position V. With this movement the respective door or tailgate swivels towards the car body against the resistance of the door seal .

In secondary position I I the drive unit 6 of the cinching aid 6 is triggered via a control unit 7 not shown in figure 2, which is activated by sensors 4 5 according to the above mentioned signals.

Figure 3 illustrates a first lock position III according to the invention which is outside secondary position I I as shown in figures 2 and 2a . In this position I I I the signal of catch sensor 4 is 0, the signal of pawl sensor 5 is still 1 . If the lock in case of high closing velocity reaches this range, the drive unit 6 of the cinching aid 6, as in position I I , will start immediately and will swivel the locking mechanism 1 2 towards primary position V in order to pull the lock 1 0 closed . I n this process the respective vehicle door or tailgate will be swiveled towards the car body. I n figure 3 the catch 1 has left the lock position I I (secondary position ) with the sensor 4 having moved from the further turned initial bevel 1 .7 of the control contour 1 .6 via the knee-formed transition range 1 .8 to the final bevel 1 .9 of the contour. I n this position the pin of sensor 4 is still lying on the final bevel, but is extended so far, that sending signal 1 is impossible. Thus, sensor 4 sends signal 0. Pawl sensor 5 is still activated by pawl sensor stop 2.2 of the pawl 2. The pawl 2 still lies in the ra nge of the secondary position stop SP which in general runs (quasi) radial to the catch rotation axis 1 . 1 . This range of the secondary positon SP is shown at larger scale in figure 3a . The ra nge covers the narrow part of the secondary position stop (secondary position tooth) , which in general (quasi) runs radial to the catch rotation axis, in front of where the pawl sinks back on the rim 1.10 of the catch 1 during the closing process.

After the catch 1 has left secondary position II of the lock, range III is the first range in which, according to the invention, at least one further lock position III can be detected and the cinching aid activated by the control devices 4 5 7. In this first further lock position III, following secondary position II, the above indicated signals will be 0 for the catch sensor 4 and 1 for the pawl sensor 5 and the drive unit of the cinching aid will be started by the control logic. The locking mechanism 1 2 will reach lock position III if the respective door or tailgate is for example closed with increased impact and therefrom resulting high closing velocity. In the state of the art positions for controlling the drive unit 6 of a cinching aid 6 which do not exactly correspond to lock position II secondary position SP have already been considered. However, the in the invention exactly defined further positions / ranges III IV for controlling the cinching aid allow for an immediate starting of the drive unit 6 of the cinching aid 6 in a position other than secondary position SP II. Therein, the contour 1.6 arranged on the catch side surface 1.5 for sensor 4 of the catch 1 is of special inventive importance for controlling the cinching aid 6. In lock position open (figure 1) the contour 1.6 counter-clockwise slopes in the range of 35° to 45°, preferably 40° from the horizontal with an initial bevel 1.7 and after passing a knee-shaped transition range 1.8 ends in a final bevel 1.9 of 90° to 100°, preferably 95°, related to the horizontal. With the transition range 1.8 created on the contour 1.6 sensor 4 of the catch 1 together with sensor 5 of the pawl 2 can seamlessly detect all lock positions III IV following secondary position SP II. Thus, according to the invention, following the lock position secondary position II a further lock position can be created, in the range of secondary position SP according to figures 3 and 3a with the positions 0 / 1 of the sensors 4 5, from which a sig nal is sent to the drive u nit 6. Having passed this ra nge I I I the pawl 2 then drops back on the rim 1 . 1 0 of the catch 1 and ends u p in range IV. The transition range 1 .8 of the contour 1 .6 secures exact switching of the sensor 4.

In figure 4 the lock during the locking operation is in a further lock position IV caused by the here invisible locking bolt 3 inserting further into the catch mouth 1 .2. This is the above described position IV, with the pawl 2 having left the range after secondary position I II and then having dropped back on the rim 1 . 1 0 of the catch 1 . Consequently, range IV in addition to range II I according to the invention is a further ra nge apart from lock positions open I , secondary position I I , and primary position V. However, in position

IV switch positions starting the drive u nit of the cinching aid 6 can be detected according to the invention . This further position IV is the range IV between the range I I I following secondary position according to figures 3 and 3a and the locked position in primary position V. The lock normally reaches this range IV if the respective door or tailgate is slammed but does not reach primary position . This range IV is shown at larger scale in figure 4a . The ra nge I n this position IV the switching com mands catch sensor 0 (switch not pressed) , pawl sensor 0 (switch not pressed) are tra nsmitted, by which according to the invention a nd in accordance with the control logic the cinching aid 6 can be definitely started .

I n figure 5 the lock has reached the main objective of the pulling close operation that is lock position V, primary position V. This position is shown at larger scale in figure 5a. The lock in this position

V is run ning before into overtravel range in order to secure safe engaging of the pawl 2 in the catch 1 and then changes to " block" . Thereby, the current consumption of the drive unit 6 abruptly increases, and the control logic 7 makes the drive unit 6 operate in reverse mode. The drive unit 6 reverses to its starting position. As already indicated the locking mechanism 1 2 when locking in place minimally overtravels primary position V into a so-called overtravel range, in order to guarantee secure engagement of the pawl 2 with the catch 1 in primary position V. This overtravel range normally lies between 1 and 3 mm in closing direction of the catch 1.

In the context of the invention the latch unit 10 also comprises an anti-trap protection (not shown in the figures), becoming active as soon as an object (resistance) entering the area between door or tailgate and the car body interrupts the cinching process. The increased current consumption caused by the resistance also causes the control unit 7 to shift the drive unit 6 to reverse mode.

Finally, figure 6 in connection with a switch diagram shows the switch sequences in the individual above mentioned lock positions and ranges I II III IV V as follows:

I. Lock position "open", if the catch sensor 4 reacts, the pawl sensor 5 does not react (signals catch / pawl 1/0).

II. Lock position "secondary position", if both sensors 4 5 react (signals 1/1).

III. Lock position after leaving secondary, if the catch sensor 4 does not respond, the pawl sensor 5 responds (signal 0/1). IV. Lock position between leaving secondary position and before reaching primary position, if both sensors 45 do not respond (signal 0/0).

V. Lock position ..primary position", if the catch sensor 4 does not respond, the pawl sensor 5 responds (signal 0/1).

In the diagram and the table in figure 6 the x-marked bar shows the ranges II III IV and V in which the drive unit 6 immediately starts when the locking mechanism makes contact, that is

II. Lock position "secondary position" if both sensors 4 5 respond (signals 1 / 1). Starting process as before.

III. Lock position after leaving secondary position (secondary position range), if the catch sensor 4 does not respond, the pawl sensor 5 responds (signals 0 / 1). First additional position (range) according to the invention for starting.

IV. Lock position between leaving the secondary position range and before reaching primary position, if both sensors 4 5 do not respond (signals 0 / 0). Second additional position (range) according to the invention for starting.

V. Lock position primary position if the catch sensor 4 does not respond, the pawl sensor 5 responds (signals 0 / 1) (pawl engaged). The starting signal as sent by catch sensor 4 = 0 and pawl sensor 5 = 1 is, like in secondary position, clearly identified by the control unit 7. This starting position is of special importance if the lock 10 only just reaches primary position V. Safe engaging of the pawl 2 shall be secured in such cases, too, by driving into the overtravel range. Such locking position can also result from environmental conditions, if for example the door seal is covered with ice or snow and loses elasticity. The end of the x-marked bar marks the stop conditions of the drive unit (block operation activated by increased current consumption of the drive unit) .

All in all, the drive unit 6 of the cinching aid 6 is started when the following signals are sent by sensors 4 5 of catch 1 and pawl 2:

With the latch unit designed as described including the switch diagram and the control unit 7 activated by sensors 4 5, an easy- to ha ndle latch u nit 1 0 with cinching aid 6 is provided , consisting of few parts only a nd with a simply-designed control logic 7 with only two sensors 4 5, guaranteeing safe pulling close and locking of the respective door or tailgate from various positions of the locking mechanism .

List of Reference N umbers: 1 : catch

1 .1 : catch rotation axis

1 .2: catch mouth 1.3: work arm

1.4 load arm

1.5 catch surface

1.6 catch sensor contour

1.7: Initial bevel contour

1.8: transition range contour

1.9 final bevel contour

1.10: catch rim

SP: catch - secondary position

PP: catch - primary position

2: pawl

2.1 : pawl rotation axis

2.2· pawl-sensor stop

3: locking bolt (bolt catch, striker)

4: catch sensor

5: pawl sensor

6: cinching aid

7: control logic

9: connection rod cinching drive unit

10: latch unit

11 : lock housing/lock plate

12: screw hole

13: screw hole

I: lock position "open"

II: lock position "secondary position"

III: lock position after leaving "secondary position"

IV:lock position between after "leaving secondary position" and reaching lock position "primary position"

V: lock position "primary position"