Vehicle occupant restraint system and method for controlling at least one belt retractor of such vehicle occupant restraint system

Abstract

The invention relates to a vehicle occupant restraint system (10), comprising a central sensor electronics (14) capable of generating a locking signal; at least one belt retractor (12) having an electromechanical locking system (20); control electronics (22) which are associated with a locking system (20) of the belt retractor (12) and which can be activated in response to a locking signal; a bus system (16), to which the sensor electronics (14) and the control electronics (22) are connected; and a line (18) which is separate from the bus system (16) and connects the control electronics (22) to the sensor electronics (14). The invention further relates to a method for controlling at least one belt retractor (12) of a vehicle occupant restraint system (10), wherein the following steps are provided: detecting a vehicle acceleration by means of sensor electronics (14); if the vehicle acceleration exceeds a predetermined limit value, a locking signal is transmitted via the bus system (16) and via a line (18) separate from the bus system (16) to control electronics (22, 26), which are associated with an electromechanical locking system of the belt retractor (12), the electromechanical locking system (20) then locking the belt reel.

Description

Technical Field

[0001] The present invention relates generally to the field of safety of vehicle occupants and seatbelt retractors of motor vehicles. In particular, the present invention relates to a vehicle occupant restraint system and a method for controlling at least one seatbelt retractor of such a vehicle occupant restraint system. Background Art

[0002] Seatbelt retractors are used to provide vehicle occupants with a seatbelt so that the vehicle occupants participate in the deceleration of the vehicle as early as possible in a critical vehicle state. For this purpose, the seatbelt reel from which the seatbelt can be unwound or rewound onto the seatbelt reel can be locked according to external parameters. This can be done mechanically, for example by means of an inertial sensor. Also known are electromechanical locking systems, with which the seatbelt reel is locked in response to an electrical locking signal.

[0003] In order to generate the locking signal, sensor electronics and control electronics are required, which can measure and evaluate the vehicle acceleration and, if necessary, actuate the electromechanical locking system.

[0004] In principle, it is conceivable to assign each seat belt retractor its own sensor electronics and control electronics. However, this is very costly.

[0005] It is also conceivable to use sensor devices that are currently present in vehicles with ESP functionality in airbag and brake control systems. These sensor devices are also suitable in terms of measuring range, accuracy and signal bandwidth for controlling electromechanical systems for locking the seat belt retractors. It is only necessary to connect the seat belt retractor, via which the sensor device provides the signal for, for example, the gas generator of the airbag system.

[0006] However, the biggest signal delay problem of bus systems in vehicles is that the transmission times of existing sensor data or locking requests are not fast enough in all scenarios to ensure a time interval until the belt reel is locked that is comparable to that of mechanical systems using electromechanical locking systems. Summary of the invention

[0007] The object of the invention is to send a locking signal to an electromechanical locking system of a seat belt retractor quickly and with a still acceptable workload when a vehicle situation exists in which the seat belt reel of the seat belt retractor should be locked.

[0008] To achieve this object, a vehicle occupant restraint system is proposed according to the invention, which has central sensor electronics, which can generate a locking signal; at least one seat belt retractor, which has an electromechanical locking system; control electronics, which are assigned to the locking system of the seat belt retractor and can activate the locking system in response to the locking signal; a bus system, to which the sensor electronics and the control electronics are connected; and a line separate from the bus system, which connects the control electronics to the sensor electronics. The invention is based on the basic idea that a locking signal is used for locking the seat belt retractor, which is provided by the central sensor electronics (i.e., the sensor electronics also used by other systems, in particular the airbag system and / or the ESP system) and is sent to the control electronics via a communication channel separate from the bus system (and therefore faster). In the event that the locking signal cannot be sent via a dedicated signal line, the bus system can be used as a backup layer. In other words, by using a fast second communication channel for transmitting the locking signal that is separate from the bus system, the problem of total transmission time (end-to-end delay) can be avoided, because the factors that have the greatest influence on the delay of the bus system (e.g. message length, waiting time until the bus is free, maximum baud rate) are eliminated. In addition, redundant transmission also has the advantage of diagnostic capabilities.

[0009] Control electronics can be assigned to a plurality of belt retractors whose locking systems are located therein, in particular if the belt retractors are without a reversible (eg electric) belt tensioning mechanism, ie if they are belt retractors which do not require complex control electronics.

[0010] The seat belt retractor may also have a seat belt tensioner. In this case, it is preferably provided that the control electronics also serve to actuate the seat belt tensioner. In particular, the control of the electromechanical locking system can be integrated into the control electronics for the seat belt tensioner, so that the assembly effort remains essentially unchanged. Only a further signal contact is required on the circuit board of the control electronics in order to connect the line capable of transmitting the locking signal.

[0011] In the case of a reversible, electromechanical seat belt retractor or a reversible, electromechanical seat belt tensioner, the control electronics (which in the context of the present disclosure may be referred to as an end stage) may be directly integrated into the seat belt retractor and / or the locking system. The actuator of the locking system may be connected directly (without a harness) to the end stage at the seat belt retractor.

[0012] The following advantages can be obtained as a result. A separate actuator ECU can be omitted. The additional wires of the fast communication channel can be integrated into the existing plug connection of the seat belt retractor ECU and / or the seat belt tensioner ECU. With such a vehicle occupant restraint system, the wiring harness in the vehicle can be simplified. Due to the short line lengths between the control electronics and the locking system, EMC requirements can be met more easily.

[0013] The sensor electronics for generating the locking signal can also be used to operate the airbag system and / or the ESP system. Generally, the sensor electronics can be a controller used in a vehicle to provide a signal for the airbag system, the ESP system, the pre-crash system, etc. in critical vehicle situations.

[0014] In order to achieve the above object, a method for controlling at least one seat belt retractor of a vehicle occupant restraint system is also provided, wherein the vehicle acceleration is detected by sensor electronics. If the vehicle acceleration exceeds a predetermined limit value or profile, a locking signal is sent via a bus system and via a line separate from the bus system to control electronics, which are associated with an electromechanical locking system of the seat belt retractor. The electromechanical locking system then locks the seat belt reel. With regard to the resulting advantages, reference is made to the above description, which applies in the same way not only to the method but also to the vehicle occupant restraint system.

[0015] The locking signal sent via a line separate from the bus system can be voltage and / or current coded. It is also possible to pulse width modulate the locking signal. This enables the transmission of a locking signal that can be clearly identified by the control electronics.

[0016] Preferably, the signal is continuously sent via the line, wherein the non-locking signal differs from the locking signal in terms of pulse width. In this way, it can be checked without doubt whether the line is in principle usable for signal transmission.

[0017] According to a preferred embodiment, the signal is continuously monitored, wherein no action is taken depending on the detected signal, a warning signal is output, or the signal is interpreted as a locking signal for safety reasons. This makes it possible to achieve a particularly high functional reliability. In particular, it is possible for the control electronics to activate the electromechanical locking system when a signal state is detected that is not clearly identified as "no locking signal".

[0018] Furthermore, the control electronics can be configured to recognize different signal amplitudes of the signal for voltage-encoded or current-encoded signals. Different signal amplitudes can satisfy different requirements: for example, for "lock requested" and for "lock not requested". Furthermore, tolerance ranges can be defined. In the amplitude range, a distinction is made between two tolerance ranges, namely between the amplitude ranges "lock requested" and "lock not requested".

[0019] The signal may have a variation curve of a partially defined function. The signal may change stepwise from a higher voltage value and / or current value to a lower voltage value and / or current value over time.

[0020] According to one specific embodiment, the control electronics are further provided for actuating an electrical locking system of the at least one belt retractor based on a pulse duty cycle of the signal and at least one predefined tolerance range.

[0021] The duty cycle of a signal can be defined as:

[0022] D=t / T

[0023] Where t is the nominal value of the signal, ie, the time during which the signal has a higher voltage and / or current, and T may define the cycle time of the signal. The definition of the duty cycle may be further explained below with reference to the accompanying drawings.

[0024] Thus, the control electronics can be configured to request locking of the seat belt retractor within a tolerance range of the duty cycle. For example, locking can be requested in a tolerance range of the duty cycle of approximately 60% to 80%. In a tolerance range of the duty cycle of approximately 30% to 60%, the control electronics can be configured not to request locking.

[0025] It is also possible for the control electronics to receive status information via the bus system. The control electronics can be informed, for example, based on a plug-in signal of a seat belt buckle associated with the seat belt retractor, which seat belt retractor of the vehicle is in use. Thus, for example, the locking system can only trigger locking if the corresponding seat is occupied. Based on this status information, the activation of the locking system can be limited to occupied seat positions.

[0026] All of the above-described embodiments with respect to the vehicle occupant restraint system also apply to the method for controlling at least one belt retractor of a vehicle occupant restraint system.

[0027] Embodiments of the present invention will be described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A vehicle occupant restraint system according to one embodiment is shown.

[0029] Figure 2A vehicle occupant restraint system according to another embodiment is shown.

[0030] Figure 3a and 3b A signal profile according to an exemplary embodiment is shown.

[0031] Figure 4a and 4b A signal profile according to an exemplary embodiment is shown.

[0032] Figure 5a and 5b A signal profile according to an exemplary embodiment is shown.

[0033] Figure 6 A signal profile according to an exemplary embodiment is shown. DETAILED DESCRIPTION

[0034] Similar, similarly acting, identical or identically acting elements are provided with similar or identical reference symbols in the figures. The figures are only schematic and not to scale.

[0035] Figure 1 A vehicle occupant restraint system 10 is shown according to one embodiment. Figure 1 The vehicle occupant restraint system 10 has a plurality of seat belt retractors 12 (shown only schematically here), sensor electronics 14 , a bus system 16 and a line 18 separate from the bus system 16 .

[0036] The seat belt retractor 12 serves to provide a vehicle occupant of a motor vehicle with a seat belt which can be unwound from a seat belt reel and wound onto the seat belt reel.

[0037] The seat belt retractor 12 has an electromechanical locking system 20 which can lock the seat belt spool in response to an external locking signal so that the seat belt cannot be withdrawn.

[0038] The structural details of the locking system 20 and of the seat belt retractor 12 are not essential for understanding the present invention and are therefore not explained in detail here.

[0039] The belt retractor 12 also has a belt tensioner, by means of which the belt reel can be rotated in the direction of winding of the belt when necessary. The belt tensioner can be a so-called high-performance tensioner, which generates a high belt force before a collision, or a so-called comfort tensioner, which pre-tensions the belt with a moderate force, for example, during strong braking. High-performance tensioners usually work irreversibly, while comfort tensioners work reversibly. A high-performance tensioner usually uses a gas generator as an energy source, while a comfort tensioner usually uses an electric motor as a drive. The structural details of the belt tensioner are not particularly important here and are therefore not explained in detail here.

[0040] It is only essential within the scope of the invention that the seat belt retractor 12 is provided with control electronics 22 for actuating the seat belt tensioning mechanism. The control electronics are connected to the bus system 16 .

[0041] The sensor electronics 14 is a control unit, in particular for controlling the airbag system and the ESP system. The control unit monitors the accelerations (positive and negative) acting on the vehicle and generates a locking signal, which indicates that the seat belt retractor 12 should be locked, if the acceleration exceeds a predetermined limit value or a predetermined curve. The sensor electronics 14 is also connected to the bus system 16.

[0042] The bus system 16 is a conventional vehicle bus system, such as a CAN bus.

[0043] The line 18 is preferably a single-wire line which is separate from the bus system 16 . It is connected to a signal output of the sensor electronics 14 and to a signal input of the control electronics 22 .

[0044] Figure 2 A vehicle occupant restraint system 10 is shown according to another embodiment. Unless otherwise specified, Figure 2 The system has Figure 1 The same elements and / or components of the vehicle occupant restraint system 10 may be used.

[0045] exist Figure 2 In the exemplary embodiment of FIG. 1 , in addition to the belt retractor 12 , two belt retractors 24 are shown which do not have a reversible belt tensioning mechanism. These belt retractors 24 do not require their own control electronics which take on the complex task of actuating the belt tensioning mechanism. Instead, external control electronics 26 are provided which are jointly assigned to a plurality of belt retractors 26 and whose task is to actuate the electromechanical locking mechanism of the belt retractors 26 .

[0046] The control electronics 26 are connected to the line 18 and the bus system 16 in the same way as the control electronics 26 integrated in the seat belt retractor 12 .

[0047] If the sensor electronics 14 detects a vehicle state which indicates that the belt reel of the belt retractor 12, 24 should be locked, the sensor electronics 14 provides a locking signal. This is sent both via the line 18 and via the bus system 16. The locking signal sent via the line 18 reaches the control electronics 26 without delay, whereas the locking signal sent via the bus system 16 reaches the control electronics 26 with the delay that is unavoidable in the bus system.

[0048] exist Figure 3a and 3b , a voltage-coded or current-coded locking signal is shown by way of example, which is generated by sensor electronics 14 . A corresponding signal can be transmitted via bus system 16 and (in the case of voltage or current coding) via line 18 .

[0049] exist Figure 3b The vertical axis, i.e., the y-axis, plots the voltage U or current I of the signal versus time (x-axis). Figure 3b The horizontal axis, ie the x-axis, reflects time t. The time variation curve of the signal can be divided into three intervals. In the first and last interval Δtk, the signal has a lower voltage or a lower current than in the interval Δts, which has a higher voltage or a higher current. The control electronics 22 is configured to interpret the signal based on the amplitude of the voltage or current.

[0050] In particular, the control electronics 22 can interpret or evaluate the interval Δts as a locking signal. The interval Δtk can be interpreted as not requiring the seat belt retractor to be locked.

[0051] Within a predefined tolerance range A of the voltage and / or current, the control electronics 22 can interpret the signal as a request for locking. In another predefined tolerance range B of the voltage and / or current of the signal, the control electronics 22 can interpret the signal as a request not to lock. If the voltage or current of the signal is outside both tolerance ranges A and B, the control electronics 22 can interpret the signal as a fault.

[0052] Figure 4a and 4b The signal profile of a signal according to a further exemplary embodiment is shown, in which the locking signal is transmitted in a pulse width modulated manner.

[0053] Figure 4a and 4bThe signal of the signal progression can be transmitted digitally. Different duty cycles can be interpreted as a locking request or no locking request. Here, tolerance bands for the two duty cycles can also be defined. All values ​​outside these tolerance bands can be interpreted as a fault. The duty cycle of the signal can be defined as:

[0054] D=t / T

[0055] Where t is the nominal value of the signal, ie the time that the signal has a higher voltage and / or current, and T may define the cycle time of the signal.

[0056] and Figure 3b similar, Figure 4b A plurality of sections can also be defined in , which can be interpreted as a locking request or as no locking request. In the section Δtk, locking of the seat belt retractor is not required, while in the section Δts, locking of the seat belt retractor is required.

[0057] Figure 5a and 5b The signal curve of a signal according to another exemplary embodiment is shown. Here, the signal is also transmitted in a pulse-modulated manner. In addition, extended safety measures are provided.

[0058] The integrity of the signal "not locking" is further ensured here by dividing the signal range into two ranges and the signal must switch between the two signal ranges at periodic intervals. If there is no switch to the other signal range within a certain time, this is interpreted as a fault. Therefore, multiple tolerance ranges for "not locking" can be defined. Figure 5a For example, two tolerance ranges B and C are shown, which are not associated with a locking request for the seat belt retractor. If there is no switch to another signal range within a time period ΔtF, this time period is interpreted as a fault.

[0059] This makes it possible, for example, to diagnose a fault in which an output function in sensor electronics 14 or an input function in control electronics 22 is not called cyclically and, therefore, the signal values ​​are not updated.

[0060] Figure 6 The signal profile of a signal according to a further exemplary embodiment is shown: In this case, a pulse width modulated signal is continuously transmitted by the sensor electronics 14 , wherein a pulse duty factor of 70% is recognized as a locking signal.

[0061] exist Figure 6 There are also extended safeguards in the signal. This includes switching the duty cycle between two values ​​during the time period outside the lock signal (such as in the "normal state"). In this embodiment, it switches between 35% and 45%.

[0062] Here you can also define a tolerance range. The tolerance range can be defined as follows.

[0063] Table 1

Claims

1. A vehicle occupant restraint system (10), comprising: Central sensor electronics (14), which are capable of generating a locking signal; at least one seat belt retractor (12), the seat belt retractor having an electromechanical locking system (20); control electronics (22) which are associated with a locking system (20) of the seat belt retractor (12) and are capable of activating the locking system in response to a locking signal; a bus system (16), to which the sensor electronics (14) and the control electronics (22) are connected; and A line (18) separate from the bus system (16) connects the control electronics (22) to the sensor electronics (14).

2. The vehicle occupant restraint system (10) according to claim 1, characterized in that: The control electronics (22) are associated with a plurality of seat belt retractors (12).

3. The vehicle occupant restraint system (10) according to claim 1, characterized in that: The seat belt retractor (12) has a reversible seat belt tensioning mechanism.

4. The vehicle occupant restraint system (10) according to claim 3, characterized in that: The control electronics (22) are also used to actuate the reversible seat belt tensioner.

5. A vehicle occupant restraint system (10) according to any one of the preceding claims, characterized in that The sensor electronics (14) are also used to activate the airbag system and / or the ESP system.

6. A method for controlling at least one seat belt retractor (12) of a vehicle occupant restraint system (10), in particular a vehicle occupant restraint system (10) according to any one of claims 1 to 5, the method comprising the following steps: detecting vehicle acceleration via sensor electronics (14); If the vehicle acceleration exceeds a predefined limit value or profile, a locking signal is sent via the bus system (16) and via a line (18) separate from the bus system (16) to control electronics (22, 26) associated with an electromechanical locking system of the seat belt retractor (12). The electromechanical locking system (20) then locks the seat belt reel.

7. The method according to claim 6, characterized in that The locking signal is voltage and / or current encoded.

8. The method according to claim 6 or 7, characterized in that: The lock signal is pulse width modulated.

9. The method according to claim 8, characterized in that A signal is continuously transmitted via the line (18), wherein the unlocking signal differs from the locking signal in terms of pulse width.

10. The method according to claim 9, characterized in that The signal is monitored continuously and, depending on the detected signal, no action is taken, a warning signal is output or, for safety reasons, the signal is interpreted as a locking signal.

Images