Method for monitoring a door contact switch of a driver's door of a motor vehicle

Abstract

Method for monitoring a door contact switch (3) of a driver's door (1) of a motor vehicle locked in a rest state, comprising the steps a) detecting the unlocking of the driver’s door (1) of the motor vehicle, b) Detecting whether a change in a door contact signal of the door contact switch (2) occurs after the driver's door (1) has been unlocked, c) Initializing a plausibility counter (P) if a change in the door contact signal has been detected, otherwise d) Detecting whether a drive device of the motor vehicle is activated, e) Setting a state “door contact implausible” and incrementing the plausibility counter (P) if the activation of the drive device was detected in step d).

Description

The present invention relates to a method for monitoring a door contact switch of a driver's door of a motor vehicle.Modern motor vehicles are often equipped with vehicle control systems. In this context, what are known as start-stop systems, for example, should be mentioned, by means of which fuel can be saved by shutting down an internal combustion engine of the motor vehicle, for example, in the event of a traffic light stop or in the event of a traffic jam. In motor vehicles with a manual transmission, the start-stop system switches off the internal combustion engine of the motor vehicle when the idle gear is engaged, as long as the driver does not actuate the clutch pedal. Upon renewed actuation of the clutch pedal, the internal combustion engine is automatically started again. In motor vehicles equipped with an automatic transmission and a start-stop system, the engine is switched off, for example, when the driver actuates the foot brake for a certain period of time when the motor vehicle is stationary. In particular in the case of motor vehicles which are equipped with such start-stop systems, it is important that the driver reliably detects the departure from the motor vehicle. Otherwise, the motor vehicle could be inadvertently restarted even though the driver is no longer located in the vehicle interior.Other vehicle control systems which are used in motor vehicles include, for example, adaptive cruise control (ACC) devices. In these adaptive cruise control devices as well, it is important that the driver should reliably identify the leaving of the motor vehicle.In order to detect whether the driver has left the motor vehicle, the door contact switches of a driver door of the motor vehicle are frequently used. These door contact switches are usually arranged in a door lock and are designed such that they are actuated by the opening or closing of the driver's door and thus generate door contact signals whether the driver's door is open or closed.In order to be able to reliably detect a door opening or door closing, two independent door contact switches are usually provided, so that in the event of a failure of one of the two door contact switches, the other, still functional door contact switch can provide a corresponding door contact signal and thus a redundancy is provided. The use of two redundant door contact switches has the disadvantage that additional component costs are caused as a result.DE 10 2010 052 582 A1 discloses a method for detecting an open door of a motor vehicle, which method operates with only one door contact switch. In this method, after an electrically driven door lock motor is activated, a counter capable of monitoring the time period after the door lock motor is activated is set. If a door contact signal of the door contact switch has not been received within a predetermined period of time, which indicates that the door has been opened, the status "door contact fault" is established and the basic state is selected again, in which it is monitored whether the door lock motor has been activated by a user.If the motor vehicle has been started multiple times without corresponding door contact signals having been detected beforehand, this method assumes that the door contact switch has a defect. For example, a fault is detected when the driver enters the motor vehicle via the passenger door and the drive device starts. Since no door contact signal was detected before the drive device was started.The present invention is based on the object of providing an improved method for monitoring a door contact switch of a driver's door of a motor vehicle with only one door contact switch and reliably detecting a possible defect of the door contact switch.Starting from a driver's door locked in a first idle state (initial state), this object is achieved by a method having the features of claim 1. Starting from a second idle state (basic state), in which a drive device of the motor vehicle is deactivated and the driver door is either locked or unlocked internally, this object is achieved by a method having the features of claim 5. The dependent claims relate to advantageous further developments of the invention.According to claim 1, a method according to the invention for monitoring a door contact switch of a driver door of a motor vehicle locked in a rest state comprises the steps: a) detecting an unlocking of the driver door of the motor vehicle, b) detecting whether a door contact signal of the door contact switch is changed after the unlocking of the driver door, c) initializing a plausibility counter (P) if a change of the door contact signal has been detected, otherwise d) detecting whether a drive device of the motor vehicle is activated, e) defining a state "door contact implausible" and incrementing the plausibility counter (P) if the activation of the drive device has been detected in step d).The method according to claim 1 permits - starting from a driver door locked in a state of rest of the motor vehicle - an effective detection of whether the driver door of the motor vehicle has been opened after unlocking. Furthermore, a possible defect of the door contact switch can also be reliably determined. This is because if the drive device has been activated after the unlocking of the driver's door of the motor vehicle, the driver must have previously actuated the driver's door. If no corresponding change in the door contact signal was detected, this indicates a defect in the door contact switch. The plausibility counter provided according to the invention forms a control variable, which can be evaluated in particular by the control device, for a possible defect of the door contact switch. If, when the method is carried out again, the change in the door contact signal has been correctly detected, the plausibility counter is initialized again.In practice, it frequently occurs that the driver door of the motor vehicle is unlocked from the outside without the driver door subsequently being opened. This is the case, for example, when only the tailgate has been opened after the unlocking in order to gain access to a luggage compartment of the motor vehicle. In order to take this circumstance into account and to avoid possible errors in the detection of the door contact signal, it is proposed in a preferred embodiment that after the detection of the unlocking of the driver's door a time measuring device is activated and it is checked whether the change of the door contact signal takes place within a defined period of time, wherein the method is continued with method step d) if the period of time has not yet expired and no change of the door contact signal has been detected and with step a) if the period of time has expired and no change of the door contact signal has been detected. Preferably, the method can be continued with method step b) if no activation of the drive device of the motor vehicle has been detected in method step d).In practice, it may also happen that the driver's door of the motor vehicle is unlocked and is locked again shortly thereafter, because, for example, the unlocking has been carried out accidentally. In order to take this circumstance into account and to avoid possible errors in the detection of the door contact signal, it is proposed in a particularly preferred embodiment that after the activation of the time measuring device and before carrying out step b) a check be made as to whether the driver's door of the motor vehicle has been locked again.According to claim 5, a method for monitoring a door contact switch of a driver's door of a motor vehicle starting from a rest state in which a drive device of the motor vehicle is deactivated and the driver's door is either unlocked or internally locked comprises the steps: a') detecting an activation of a drive device of the motor vehicle, b') continuing the method with method step a') if the drive device of the motor vehicle has not been activated, otherwise c') detecting whether a change of a door contact signal of a door contact switch (2) has taken place before the setting into the rest state, d') initializing a plausibility counter (P) if a change of the door contact signal has been detected, otherwise e') defining a state "door contact implausible" and incrementing the plausibility counter (P).The method according to claim 5 permits - starting from a driver door which is unlocked or internally locked in a state of rest of the motor vehicle and the drive device which is deactivated - a detection as to whether the driver door of the motor vehicle has been opened before the start of the motor vehicle. Furthermore, a possible defect of the door contact switch can be reliably determined. This is because if the drive device has been started, but no change in the door contact signal has been detected before the switch to the idle state, the driver's door must have been actuated. If no corresponding change in the door contact signal was detected, this indicates a defect in the door contact switch. The plausibility counter provided according to the invention also forms here a control variable, which can be evaluated in particular by the control device, for a possible defect of the door contact switch. If, when the method is carried out again, the change in the door contact signal has been correctly detected, the plausibility counter is initialized again.In contrast to the prior art, in the method according to the invention as claimed in claim 1 and claim 5, the status of the drive device is advantageously also observed and used for plausibility checking the function of the door contact switch.In a preferred embodiment, it can be provided that a service life t_Stand of the motor vehicle is determined and a service life factor for incrementing the plausibility counter is calculated therefrom. The lifetime factor can be calculated, for example, by dividing the lifetime (measured in minutes) by a factor of 10.In a particularly preferred embodiment, it is proposed that a service life limiting value ts_MAX is set and it is checked whether the service life t_Stand is greater than the service life limiting value ts_MAX, wherein the service life factor is calculated from the service life t_Stand if t_Stand<ts_MAX, and otherwise the service life factor is calculated from the service life limiting value ts_MAX. In this way, in the case of long service lives, excessive incrementing of the plausibility counter by the service life factor calculated in the manner described above can be avoided.In one expedient embodiment, the activation of the drive device of the motor vehicle can be detected by checking the operating status of an ignition device of an internal combustion engine of the drive device of the motor vehicle and / or by checking whether a rotational speed of the internal combustion engine is greater than 0.In a further advantageous embodiment, it is proposed that after the activation of the drive device it is checked whether after renewed deactivation of the drive device a change of the door contact signal of the door contact switch takes place, wherein the plausibility counter is incremented if no change of the door contact signal has been detected and the drive device has not been activated again. This is because in this case, in which the drive device has been deactivated and subsequently not activated again, it is to be assumed that the driver has very probably left the motor vehicle and the opening of the driver's door has not been correctly detected.A fault in the door contact switch is present if the plausibility counter has exceeded a specific preset threshold value. This prevents an error message from being generated, for example, when an implausible door contact is detected once.According to a further aspect, the present invention relates to a motor vehicle, comprising a door having a door contact switch for detecting an open or closed state of the driver's door, and a control device which is connected to the door contact switch. According to the invention, the control device is configured to carry out a method according to one of Claims 1 to 9.Further features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. Figure shows FIG. 1 shows a schematic illustration of a driver's door of a motor vehicle and of a control device for carrying out a method for monitoring a door contact switch of the driver's door, FIG. 2 shows a functional flow diagram illustrating the sequence of the method, starting from a driver door of the motor vehicle which is locked in a rest state, FIG. 3 is a functional flow diagram illustrating the sequence of the method, starting from a rest state in which a drive device of the motor vehicle is deactivated and the driver door is either unlocked or internally locked, FIG. 4 shows a function flow diagram which illustrates an evaluation of a plausibility counter, FIGS. 5 to 8 show four possible functional sequences of the method described here.FIG. 1 shows a driver door 1 of a motor vehicle and a control device 2 which is configured to carry out a method for monitoring a door contact switch 3 of a driver door 1 of a motor vehicle according to a preferred exemplary embodiment of the present invention. The driver's door 1 has a door contact switch 3, which is preferably integrated into a door lock 10 and is connected to the control device 2 by means of a connecting line 4. The connection line 4 can be in particular a field bus line, preferably a CAN bus line. The locking or unlocking of the driver's door 1 can be effected mechanically or optionally with the aid of an electric door lock motor, which can preferably be integrated into the door lock 10 of the driver's door 1. In a known manner, the driver's door 1 equipped with the door contact switch 3 comprises (at least) one handling means, in particular a handling handle, not explicitly shown here, on an outer side and on an inner side, so that the unlocked driver's door 1 can be opened or closed again from the outside or the inside.The door contact switch 3 is configured to be able to detect whether the unlocked driver's door 1 of the motor vehicle has been opened or closed. Accordingly, either a door contact signal "DOOR_LOCKED" if the driver's door 1 has been closed or a door contact signal "DOOR_OPENED" if the driver's door 1 has been opened is provided to the control device 2 via the connection line 4 for further processing. Changes in the door contact signal (i.e., from "TUR_LOCK" to "TUR_OPENED" and vice versa) are relevant for the further processing.The control device 2 is designed such that it can receive and evaluate further vehicle state information and / or time information. These mentioned information that can be evaluated by the control device 2 can include, for example:date,time, time,status (on / off) of an ignition device 5 of an internal combustion engine 6 of the motor vehicle,engine speed n of the internal combustion engine 6,status information as to whether locking of the driver's door 1 has taken place from the outside (status signal: "EXT_LOCK") or from the inside (status signal: "INT_LOCK") or unlocking of the driver's door 1 has taken place.From a change of the door contact signal from "DOOR_LOCK" to "DOOR_OPENED" or from "DOOR_OPENED" to "DOOR_LOCK" and the further information additionally provided to the control device 2, it is possible to reliably detect, inter alia, in the manner described below, whether the driver door 1 has been opened after the unlocking or whether the motor vehicle has been left after the internal combustion engine 6 has been switched off. Further, it is possible to detect a possible failure of the door contact switch 3.After the driver's door 1 of the motor vehicle has been unlocked, the control device 2 checks whether a change in the door contact signal of the driver's door 1 from "DOOR_LOCK" to "DOOR_OPENED" has been made available by the door contact switch 3. If a change in the door contact signal could be detected, no malfunction apparently occurs. If no change in the door contact signal was detected, but the internal combustion engine 6 of the motor vehicle was started, the driver's door 1 of the motor vehicle must have been opened at a point in time before the internal combustion engine 6 was started. This situation allows the conclusion that the door contact switch 3 may be defective. A plausibility counter P, which is stored in the control device 2, is incremented.With reference to FIG. 2, a functional flow diagram is explained in more detail below, which illustrates the aspect of the method explained above in more detail. In a rest state (basic state), the driver door 1 of the motor vehicle is locked. After the program start 200, an initialization is initially carried out in a step 201. Then, in a step 202, it is checked whether the driver's door 1 of the motor vehicle is either externally locked or locked in a safety lock mode. With the "simple" external locking, there is still the possibility for vehicle occupants to unlock the driver door 1 from the inside. In the safety locking mode, an unlocking of the driver's door 1 from the inside is no longer possible. Frequently, in this safety locking mode, interior monitoring means of an alarm device of the motor vehicle are also activated.If, in step 202, an external locking of the driver's door 1 cannot be detected in the "simple" locking mode or in the safety locking mode, a return to the initialization step 201 takes place. If a locking of the driver's door 1 has been detected, a corresponding state variable ("LOCK" or "SAFETY LOCK") is set in step 203, depending on the locking type, which state variable indicates that the motor vehicle is locked in one of the two mentioned locking modes. In a next step 204, a check is made as to whether the driver's door 1 of the motor vehicle has been externally unlocked. If no, the corresponding state variable ("LOCK" or "SAFETY LOCK") is set again in step 203, and the method is continued at this point with a renewed check as to whether the driver's door 1 has been unlocked. If external unlocking could be detected, a time measuring device is started in step 205, which is set to a specific time value t_Max (for example, three minutes). Furthermore, in step 206, a corresponding state variable ("UNLOCK_OUTVERX") is set, which indicates that the driver door 1 of the motor vehicle has been externally unlocked.In a next step 207, it is checked whether the driver door 1 of the motor vehicle has possibly been locked externally again, because, for example, the previous external unlocking has accidentally taken place and this provision has been recognized by the operator. If yes, the method is returned to initialize (step 201). If no, it is determined in a step 208 whether the door contact signal of the door contact switch 3 (presently, from "DOOR CLOSED" to "DOOR OPENED") has changed. This thus checks whether the driver's door 1 of the motor vehicle has been opened after the external unlocking and the control device 2 has been transmitted the door contact signal "DOOR_OPENED". If so, the door contact switch 3 apparently operates correctly and a return is made to the initialization step 201. If no, a check is made in a step 209 as to whether the time value t_Max of the time measuring device has expired. If yes, the driver's door 1 of the motor vehicle has been externally unlocked, but is very likely not to be opened from the outside. This situation may occur, for example, when the driver's door 1 has been accidentally unlocked but this provision has not been recognized by the operator. A return to the initialization step 201 takes place again. If the time value t_Max of the time measuring device has not yet expired, there is a possibility, to a certain extent, that the driver has opened the driver door 1 of the motor vehicle and is located in the vehicle interior, wherein the opening of the driver door 1 has not been detected. In a next step 210, the status of the ignition device 5 of the motor vehicle is therefore checked. If the ignition device 5 is not switched on, a return to step 206 takes place. In this case, the corresponding state variable ("UNLOCK_OUTVERX") is set again and the method is continued at this point in the functional flow diagram. If the ignition device 5 has been activated, a check is made in a next step 211 as to whether the engine speed n of the internal combustion engine 6 is greater than 0. If no, a return is made again to step 206, in which the corresponding state variable ("UNLOCK_OUTVER") is set. The method is then continued again at this point in the functional flow diagram. If the rotational speed n>0, the internal combustion engine 6 of the motor vehicle has obviously been started successfully, although at no time could an opening of the driver's door 1 of the motor vehicle be detected by the door contact switch 3. Accordingly, in a step 212, a state variable ("door contact implausible") is set and the plausibility counter P is incremented accordingly by a parameter value PAR in a step 213. For example, the parameter value may be set to a numerical value PAR=10.With reference to FIG. 3, the situation of a longer service life when the driver's door 1 is unlocked or internally locked and the drive device of the motor vehicle is deactivated will be explained in more detail below. The aim is to check whether the driver has left the motor vehicle after the internal combustion engine 6 has been shut down. In contrast to FIG. 2, in the idle state (basic state), the driver door 1 of the motor vehicle is thus unlocked or locked internally. Furthermore, the drive device of the motor vehicle is deactivated. After the program start in method step 300, an initialization is initially carried out in a step 301. In a next step 302, it is checked whether the ignition device 5 of the internal combustion engine 6 of the motor vehicle has been activated. If no, the system returns to initialization in step 301 and the method continues with a renewed check at this point as to whether ignition device 5 has been activated. If the ignition device 5 has been activated, a corresponding state variable "IGNITION ON" is set in step 303. In a next step 304, it is then checked whether the engine speed n of the internal combustion engine 6 is greater than 0. If no, the system returns to step 303 and it is checked again in step 304 whether the engine speed is n>0. If an engine speed n>0 is detected, a check is made in step 305 as to whether a change in the door contact signal of the door contact switch 3 was detected before the idle state. If yes, the function of the door contact switch 3 is obviously not impaired and the leaving of the motor vehicle has been correctly recognized. The process returns to the initialization step 301. If no, a state variable "door contact implausible" is set in step 306, since no change in the door contact signal of the door contact switch 3 has been detected and there is apparently a fault.In a next step 307, the service life t_Stand of the motor vehicle is calculated. For this purpose, date information can optionally also be used in addition to time information. Preferably, a service life limit value ts_MAX can be stored in the control device 2. This lifetime limiting value ts_MAX may be set to ts_MAX=100 minutes, for example. In the following step 308, a check is now made as to whether the calculated service life t_Stand is greater than ts_MAX. If no, the plausibility counter P is incremented by a service life factor STAND in a step 310. One possible calculation for the service life factor STAND is: STAND=service life (in minutes) / 10. If the service life t_service life is greater than ts_MAX, the service life t_service life is limited to this value in step 309 and is used to calculate the service life factor STAND in the manner described above. This prevents excessive incrementing of plausibility counter P, particularly in the case of very long service lives, since service life t_Stand is limited to ts_MAX.With reference to FIG. 4, the evaluation of plausibility counter P, which can be carried out with the aid of control device 2, is to be explained in more detail below. After the start 400, a check is made in a first step 401 as to whether the door contact switch 3 has provided a door contact signal which indicates a change of state of the driver's door 1 (i.e. a change of the door contact signal from "DOOR_LOCK" to "DOOR_LOCK" or from "DOOR_LOCK to DOOR_LOCK"). If yes, plausibility counter P is initialized in a step 402 and set to a value P=0. If no, a check is made in a step 403 as to whether plausibility counter P has exceeded a threshold value P_threshold, so that P>P_threshold applies. The threshold P_Threshold may be set to P_Threshold=20, for example. If the threshold value P_threshold has been exceeded, the door contact signal is implausible and there is obviously a fault in the door contact switch 3. In step 404, the "door contact fault" state is set. If there is no exceeding of the threshold value P_threshold, the door contact signal is still plausible and the door contact switch 3 does not have any malfunction. In step 405, the "door contact plausible" state is set.With reference to FIGS. 5 to 8, four possible functional sequences will be explained in more detail below. In FIGS. 5 and 6, the initial situation (idle state) is in each case a driver door 1 of the motor vehicle locked at the time of the start 500, 600. In FIGS. 7 and 8, the driver door 1 is either unlocked or internally locked in the idle state at the time of the start 700, 800. Furthermore, at the time of the start 700, 800, the drive device of the motor vehicle is deactivated.Referring to FIG. 5, in a step 501, the driver door 1 is unlocked and the unlocking of the driver door 1 is detected by the controller 2. Subsequently, the driver's door 1 of the motor vehicle is opened in a step 502, wherein a corresponding change of the door contact signal is made available to the control device 2 by the door contact switch 3. Subsequently, the internal combustion engine 6 of the motor vehicle is started in a step 503 and a rotational speed n>0 is detected. Since the door opening was correctly detected before the internal combustion engine 6 was started, no detection takes place in step 504 according to the functional sequence presented in FIG. 2. Furthermore, the plausibility counter P is initialized in step 505 and set to a value P=0 since the function of the door contact switch 3 is obviously not impaired.FIG. 6 shows the situation in which the internal combustion engine 6 of the motor vehicle has been activated (step 602), but the opening of the driver's door 1 after the unlocking has not been correctly detected by the door contact switch 3 in the preceding step 601. In step 603, a detection takes place according to the method shown in FIG. 2, and plausibility counter P is incremented accordingly in step 604.According to FIG. 7, after the start (step 700), the driver's door 1 of the motor vehicle is opened in step 701 and a change in the door contact signal is made available to the control device 2 by the door contact switch 3. Subsequently, the internal combustion engine 6 of the motor vehicle is started in step 702 and a rotational speed n>0 of the internal combustion engine 6 is detected. Since the door opening was correctly detected before the internal combustion engine 6 was started, no plausibility check is carried out in step 703 according to the sequence presented in FIG. 3. Plausibility counter P is initialized in step 704 and set to a value P=0 since the function of door contact switch 3 is not impaired.FIG. 8 shows the situation in which, after the start (step 800) with the motor vehicle unlocked, no change in the door contact signal was detected in step 801 before the internal combustion engine 6 was started. Then, in step 802, fault detection takes place according to the method shown in FIG. 3, and the plausibility counter P is incremented by the service life factor STAND in step 803.

Claims

Method for monitoring a door contact switch (3) of a driver's door (1) of a motor vehicle which is locked in a state of rest, comprising the steps a) detecting unlocking of the driver's door (1) of the motor vehicle, b) detecting whether a door contact signal of the door contact switch (2) changes after unlocking of the driver's door (1), c) initializing a plausibility counter (P) if a change in the door contact signal has been detected, otherwise d) detecting whether a drive device of the motor vehicle is activated, e) defining a state "door contact implausible" and incrementing the plausibility counter (P) if the activation of the drive device has been detected in step d).Method according to Claim 1, characterized in that, after the detection of the unlocking of the driver's door (1), a time measuring device is activated and a check is carried out to determine whether the change in the door contact signal takes place within a fixed time period (t_Max), wherein the method is continued with method step d) if the time period (t_Max) has not yet expired and no change in the door contact signal has been detected, and with step a) if the time period (t_Max) has expired and no change in the door contact signal has been detected.Method according to Claim 2, characterized in that the method is continued with method step b) if no activation of the drive device of the motor vehicle has been detected in method step d).Method according to either of Claims 2 and 3, characterized in that, after the activation of the time measuring device and before carrying out step b), it is checked whether the driver's door (1) of the motor vehicle has been locked again.Method for monitoring a door contact switch (3) of a driver's door (1) of a motor vehicle starting from a rest state in which a drive device of the motor vehicle is deactivated and the driver's door (1) is either unlocked or internally locked, comprising the steps a') detecting an activation of a drive device of the motor vehicle, b') continuing the method with the method step a') if the drive device of the motor vehicle has not been activated, otherwise c') detecting whether a change of a door contact signal of a door contact switch (3) has taken place before the setting into the rest state, d') initializing a plausibility counter (P) if a change of the door contact signal has been detected, otherwise e') defining a state "door contact implausible" and incrementing the plausibility counter (P).Method according to Claim 5, characterized in that a service life (t_Stand) of the motor vehicle is determined and a service life factor for incrementing the plausibility counter (P) is calculated therefrom.Method according to Claim 6, characterized in that a service life limiting value (ts_MAX) is set and a check is carried out to determine whether the service life (t_Stand) is greater than the service life limiting value (ts_MAX), the service life factor being calculated from the service life (t_Stand) if t_Stand<t_Stand_Max, and otherwise the service life factor being calculated from the service life limiting value (t_Stand_Max).Method according to one of Claims 1 to 7, characterized in that the activation of the drive device of the motor vehicle is detected by checking the status of an ignition device (5) of an internal combustion engine (6) of the drive device of the motor vehicle and / or by checking whether a rotational speed (n) of the internal combustion engine (6) is greater than 0.Method according to one of Claims 1 to 8, characterized in that, after the activation of the drive device, it is checked whether, after renewed deactivation of the drive device, a change in the door contact signal of the door contact switch (3) takes place, wherein the plausibility counter (P) is incremented if no change in the door contact signal has been detected and the drive device has not been activated again.Motor vehicle, comprising a driver door (1) with a door contact switch (3) for detecting an open or closed state of the driver door (1) and a control device (2) which is connected to the door contact switch (3), characterized in that the control device (2) is configured to carry out a method according to one of Claims 1 to 9.

Images