Seatbelt retractor unit and vehicle with such a seatbelt retractor unit

Description

[0001] The invention relates to a belt retractor unit according to the preamble of claim 1.

[0002] Every modern passenger vehicle, as well as most trucks, buses, and similar vehicles, is equipped with seat belt systems. Such a seat belt system always includes a belt retractor unit, which in turn comprises a belt retractor with a housing and a belt spool rotatably mounted within this housing. A portion of the seat belt webbing is wound onto this spool, and the user can unwind it against the force of a return spring acting between the spool and the housing. A locking mechanism is also provided, which has a release state in which the belt spool is not locked against the housing, and a locking state in which the belt spool is locked against the housing.This locking device typically has two independent sensors: a belt-sensitive sensor that detects the rotation of the belt reel, and a vehicle-sensitive sensor that detects the vehicle's orientation and / or acceleration (especially deceleration). Under normal driving conditions, i.e., when the seatbelt is not extended too quickly, the vehicle is in an unusual position, and there is no unusual acceleration, the locking device is in its unlocked state, allowing the user to extend the seatbelt with relative freedom of movement. However, if the seatbelt is extended too quickly, the vehicle decelerates too rapidly, or the vehicle tilts excessively from its normal orientation, the locking device engages.

[0003] Currently, most locking devices are fully mechanical, meaning that the entire locking mechanism (including the sensors) is rigidly connected to the seatbelt retractor housing. This rigid connection of the entire locking mechanism to the housing has disadvantages, however, especially when the seatbelt retractor unit is attached to the vehicle seat, particularly its backrest, as the position of the retractor, and therefore also of the vehicle-sensitive sensor, can change relative to the vehicle.

[0004] Therefore, fully or partially electrically operated seatbelt retractor units are also known, whose locking device comprises a locking unit connected to the housing with an electromagnet and a control unit for actuating the electromagnet. The electromagnet is part of an electrically controllable actuator unit such that the state of the actuator unit (in particular, de-energized or energized) determines the state of the locking unit (belt retractor rotatable or belt retractor locked). Normally, the locking unit also includes a return element (usually in the form of a spring) that opposes the electromagnet. This return element can be part of the actuator unit. For safety reasons (fail-safe), the de-energized state is generally the locked state (emergency state), and the energized state is the unlocked state (release state).Accordingly, the control unit that operates the actuator unit, which has a power input connected to the vehicle's electrical system and a power output connected to the electromagnet, has a passive switching state in which the current supply from the power input to the power output is interrupted, and an active switching state in which the power input is connected to the power output and therefore current flows through the electromagnet. This control unit, which is generally only electrically coupled to the locking unit, can in this case be located anywhere in the vehicle, in particular in such a way that it does not move with the seat back. The control unit has at least one sensor and one switching device for controlling the actuator unit depending on the data supplied by the sensor.The control unit can form a structural unit, but it doesn't have to.

[0005] The most important criterion for the transition from the enabled state to the emergency state is that the magnitude of at least one horizontal acceleration value exceeds a limit. Often it is not necessary to distinguish between accelerations in the longitudinal direction (X-direction) and the lateral direction (Y-direction) of the vehicle, and only the magnitude of the acceleration in the XY plane is considered.

[0006] A generic seatbelt retractor unit with such a locking unit and such a control device is described, for example, in GB 23 98 824 B or WO 2004 / 065184 A1. Such electrically operated seatbelt retractor units have further advantages, as they offer more possibilities for controlling the state of the seatbelt retractor unit (locked / unlocked).

[0007] Starting from this premise, the present invention aims to further improve a generic belt retractor unit.

[0008] This problem is solved by a belt retractor unit having the features of claim 1.

[0009] To best protect the occupants, it is generally advisable for the seatbelt locking mechanism to activate at an early stage, particularly even before the actual accident occurs, for example, when the vehicle decelerates sharply. For this purpose, the threshold for horizontal acceleration at which the seatbelt locking mechanism engages should be relatively low. However, this has the consequence that, at least under certain conditions, the seatbelt retractor unit will relatively frequently enter its locked state (hereinafter also referred to as the emergency state), even when there is no actual danger. In other words, the locking of the belt retractor is unnecessary and is then released again. This in itself is not a problem and is accepted in favor of the overall improved occupant safety.

[0010] However, it has been found that when selecting the threshold value preferred for vehicle occupant safety (i.e., a low threshold value), particularly under poor road conditions, the seatbelt locking mechanism can switch to its emergency state, in which the belt retractor is locked against the housing, simply due to vehicle vibrations. While this in itself is not problematic, it has also been found that, especially in the scenario described above, the acceleration forces acting on the vehicle (and thus also on the sensor unit) frequently fluctuate around the selected threshold value under poor road conditions. This causes the seatbelt retractor unit to switch back and forth between the emergency and release states relatively frequently – and at a high frequency.This is associated with disruptive noise and also leads to increased wear and tear on the mechanical components involved. Both are obviously undesirable: The increased noise negatively impacts comfort; this is all the more so since a particular advantage of this type of seatbelt retractor unit is that the housing is located in the seat backrest and thus often near the occupant's ear. The increased wear and tear is also detrimental because the lifespan of a seatbelt retractor unit should be aligned with the lifespan of the entire vehicle.

[0011] To solve the problem described above, the actuator unit is controlled by the control device in a hysteresis manner, namely in such a way that there are two different limit values ​​for the amount of horizontal acceleration, namely a first limit value at which the blocking unit transitions from its release state to the emergency state - hereinafter: first emergency state - and a second limit value at which the belt retractor unit returns from its first emergency state to the release state, whereby this second limit value is smaller in magnitude than the first limit value.

[0012] This prevents constant switching back and forth by allowing the seatbelt retractor unit to remain in the emergency state for a longer period in certain situations – especially under specific road conditions. This is significantly more convenient for the user than a constant switching between the emergency and release states. Naturally, this also reduces the number of switching cycles, which has a positive effect on the lifespan of the seatbelt retractor unit.

[0013] Furthermore, it is provided that the seatbelt retractor unit transitions from its emergency state to the release state only when the magnitude of at least one horizontal acceleration value remains below a third limit value for a predetermined period of time, which is at least 250 ms, after having fallen below the second limit value. This third limit value is preferably located between the second and the first limit value and can, in particular, also be identical to the first limit value.

[0014] As previously mentioned, the seatbelt retractor unit must lock both when sufficient acceleration occurs (which is usually negative acceleration, i.e., deceleration) and when the vehicle tilts by more than a predetermined amount around its longitudinal or transverse axis. In such a tilt, the vehicle's Z-axis always leans relative to the vertical, so the degree of tilt can be described by a single angle. A single conventional mechanical sensor cannot distinguish between these two cases. The situation is different when using an electronic sensor: here, acceleration and tilt can be differentiated.Since it is crucial that the seatbelt retractor unit transitions from the enabled state to an emergency state when both an acceleration limit and a tilt limit are exceeded, the sensor should measure both values. However, it is preferable for these values ​​to be processed separately by the switching device, specifically in such a way that the tilt relative to the vertical axis is disregarded when determining the first emergency state. This reduces the number of unnecessary transitions from the enabled state to the first emergency state, particularly on uneven roads, as it has been found that the influence of uneven roads on acceleration in the XY plane is often relatively small, while the influence on vehicle tilt, especially around the X-axis, is often relatively large.

[0015] To compensate for the failure to consider the inclination about the vertical axis when determining the first emergency state, the belt retractor unit preferably has a second emergency state in which the belt spool is also blocked against the housing and which depends exclusively on the inclination.

[0016] The invention will now be explained in more detail with reference to a preferred embodiment and the figures. These show: Figure 1 A schematic representation of a belt retractor unit, wherein the belt retractor of this belt retractor unit is shown in a schematic side view, wherein the control device is in an open switching state and wherein the belt retractor is in its locked state, Figure 2 the in Figure 1 shown belt retractor in a schematic top view from above, from the direction of R1, Figure 3 Figure 1Figure 4a shows a side view of a car and the associated coordinates, with the control device in its closed switching state and the seatbelt retractor in its unlocked state. Figure 4b shows a top view of the car. Figure 4a from above and the associated coordinates, Figure 4c a top view of the car from Figure 4a from behind and the associated coordinates, Figure 5 the car in the representation of the Figure 4a in a head-on collision, Figure 6 the car in the depiction of the Figure 4b in a side collision, Figure 7 the car into a representation of the Figure 4a , when tilted around the Y-axis, Figure 8 shows the car in a representation of the Figure 4c , when tilted about the X-axis, Figure 9a shows a more detailed representation of an embodiment of a control device as described in the Figures 1 and 3simplified representation, showing it in its release state, Figure 9b the control unit from Figure 9a , in its first emergency state, Figure 9c the control unit from Figure 9a , in its second emergency state, Figure 9d the control unit from Figure 9a , in which it is in a double emergency state, Figure 10 a flowchart of a first preferred control sequence of the logic unit, Figures 11a and 11 a schematic representation of a mechanical analogue of the left branch of the in Figure 10 The control sequence shown and Figure 12 a flowchart of a second preferred control sequence of the first logic subunit.

[0017] With regard to the Figures 1 and 2First, the essential features of a seatbelt retractor unit according to the invention will be described. It should be noted that the illustrations are highly schematic and only depict the basic principles of the invention. The seatbelt retractor unit can be considered to consist of the seatbelt reel 10 and the control unit 50. The control unit 50 could be directly connected to the housing of the seatbelt retractor 10, but this is not necessary, which is why it is shown in the Figures 1 and 3 also shown as being removed from the housing. Naturally, the control unit and the belt retractor must be electrically connected.

[0018] The following diagrams show electrical lines only schematically (and not with forward and return conductors). Power lines are represented as solid lines and signal lines as lines with the pattern "dash-colon-dash".

[0019] The belt retractor 10 consists, as usual, of a housing 10, a belt spool 20 rotatably mounted in the housing on which a section of a webbing 5 is wound, and a locking unit for locking the belt spool 20 in the housing 12. In the illustrated embodiment, the housing 12 has two housing plates 14a, 14b connected by connecting bolts 16; however, this is only to be understood as an example. Typically, and this is also shown here, the locking unit has a locking wheel 22 that is non-rotatably connected to the belt spool 20. A pawl 24a is also provided, which, in the locked (emergency) state, Figure 1 ) the locking wheel 22 and thus the belt spool 20 is blocked against the housing 12, in the release state ( Figure 3 ) but not.

[0020] It is essential that the position of the pawl 24a is controlled directly (as shown) or indirectly by an actuator unit 40 comprising an electromagnet 42. In the illustrated embodiment, this control is achieved by the actuator unit 40 having, in addition to the electromagnet 42, a plunger 44 driven by the electromagnet, which acts on a lever 24 carrying the pawl 24a. When a sufficiently strong current flows through the electromagnet, it pushes the plunger 44 outwards. As already mentioned, however, it should be noted that this design is only exemplary. The essential point is that the locking unit has an electromagnet such that the actuator unit controls the locking unit depending on the current flowing through the magnet.As a rule, and this is also shown, a spring, here a tension spring 30, or another elastic element is provided which uniquely defines the state of the locking unit when the electromagnet 42 of the actuator unit 40 is de-energized and thus exerts no force on the plunger it drives. This de-energized state is, as also shown in the figures, the locked state.

[0021] Such electrically controlled locking units with an electromagnet are known in the prior art. The invention therefore relates exclusively to the control of the electromagnet, i.e., the control device 50.

[0022] In preparation for the detailed description of the invention based on the description of the control device and its operation, the following will first be discussed with reference to the Figures 4a to 8 Some general statements were made and definitions were established: The Figure 4ashows a schematic side view of a car and the associated coordinates, namely the longitudinal direction X and the vertical direction Z, which Figure 4b This shows in Figure 4a Figure 4c shows the car in a top view, as well as the associated coordinates, namely the longitudinal direction X and the transverse direction Y. Figures 4a and 4b in a rear view as well as the associated coordinates, namely the transverse direction Y and the vertical direction Z.

[0023] Figure 5 This shows a typical frontal crash. Here, the velocity changes in the X-direction, meaning the second derivative of the X-coordinate with respect to time is not equal to 0: d² < X / dt² < ≠ 0, and the magnitude of the acceleration in the X-direction, and therefore also in the XY-plane, is greater than 0: |a XY | > 0. Accordingly, in a side impact ( Figure 6), that the second derivative of the y-coordinate with respect to time is not equal to 0: d 2< Y / dt 2< ≠ 0; here too, the magnitude of the acceleration in the XY plane is greater than 0: |a XY | > 0. This means that a criterion for locking the belt is that the magnitude of the acceleration in the XY plane exceeds a predetermined limit.

[0024] The Figure 7 and 8This illustrates another scenario that must trigger the locking of the webbing: a vehicle rollover. A vehicle rollover always means that the vehicle's Z-coordinate (here denoted as Z') is inclined relative to the vertical direction Z. The locking criterion here should be that the inclination—which can be expressed by the angle ΔZ between Z and Z'—exceeds a predetermined value. The dynamics (i.e., the speed or acceleration of the change) and the direction are irrelevant; therefore, a specific value of ΔZ can be defined as the limit for locking.

[0025] In the preferred embodiment described below, all relevant orientation and acceleration data are measured by a common sensor device but processed separately by a downstream switching device. This will first be explained using a schematic circuit diagram. It should be emphasized that this circuit diagram represents only one possibility. The corresponding separation of the information can also be achieved differently using circuitry or software.

[0026] The Figure 9a Figure 1 shows a schematic embodiment of a control device 50. This control device 50 can be designed as a control unit which contains all relevant components; however, it is also possible that individual elements of the control device are "distributed throughout the vehicle", which is generally not preferred.

[0027] As already mentioned, the control unit 50 serves to control the current flow from the vehicle electrical system to the electromagnet 42, that is, to enable and interrupt it. It therefore has a power input 55 connected to the vehicle electrical system and a power output 56 connected to the electromagnet, with a switching unit 80 arranged between them. When the switching unit is closed, current from the vehicle electrical system flows through the electromagnet; when the switching unit 80 is open, it does not. It should also be mentioned that a DC-DC converter acting as a constant current source could be provided to supply the electromagnet with only the required amount of current when the switching unit is closed. This converter could also be designed in two stages, supplying an inrush current and a smaller holding current. However, this will not be described in detail below.

[0028] The control unit 50 comprises, in addition to the aforementioned switching unit 80, a sensor unit 60 and a logic unit 74. This logic unit 74 and the switching unit 80 together form the switching device 70.

[0029] The sensor device 60 (which could also simply be called a sensor) is, in the preferred embodiment shown, a three-axis sensor that continuously measures the orientation and acceleration in all three spatial directions and transmits the measurement data to the switching device 70. This switching device, as mentioned above, consists, at least functionally, of the logic unit 74 and the switching unit 80.

[0030] The data supplied by the sensor device 60 are processed by the logic unit 74 in two separate processes: In one process, only the acceleration in the XY plane is processed, and in another, the tilt about the Z-axis. Therefore, the logic unit 74 functionally comprises a first logic subunit 74a, which handles the acceleration evaluation in the XY plane, and a second logic subunit 74b, which handles the tilt evaluation. In the illustrated embodiment, these two logic subunits 74a and 74b control two switches 80a and 80b connected in series, which in turn form the switching unit 80. This embodiment of the switching unit is chosen particularly for the purpose of illustrative demonstration, but could also be implemented in this way in practice.

[0031] As described above, the de-energized state of the electromagnet 42 is the locked state of the belt retractor 10 ( Figure 1), while the current-carrying state is the unlocked state.

[0032] As mentioned above, logic unit 74 comprises a first logic subunit 74a, which evaluates the acceleration values ​​in the XY plane, and a second logic subunit 74b, which evaluates the toggle values ​​ΔZ. Naturally, the unlocked enable state (the current-carrying state of the electromagnet) should only exist if both logic subunits 74a and 74b result in "unlocking." This is implemented in the circuit by having the first logic subunit 74a control the first switch 80a of switching unit 80, and the second logic subunit 74b control the second switch 80b of switching unit 80. Since these two switches 80a and 80b are connected in series, both switches 80a and 80b must be in the "on" state (closed, as shown in Figure 8a) to generate the unlocked state (enabled state). In all other cases ( Figures 9b to 9d) a locked state (emergency state) exists. With respect to the unlocked state, this circuit therefore forms a logical AND.

[0033] With regard to the Figure 10 A first algorithm according to the invention, which is executed by the logic unit 74, will now be described. As already indicated above, the two logic subunits 74a and 74b operate in parallel and preferably independently of each other. In the flowchart of the Figure 10The left tree shows the flowchart of the first logic subunit 74a, and the right tree shows the flowchart of the second logic subunit 74b. The relevant measurement for the first logic subunit 74a is the magnitude of the acceleration in the XY plane, i.e., the horizontal acceleration |a XY |. The process is as follows: After the vehicle starts, a first step checks whether the magnitude of the acceleration in the XY plane |a XY | is less than a first limit value ah < 1. Since the vehicle should remain stationary in this state, an alarm can be triggered, for example, if the acceleration value is greater than this limit value, as this indicates either a technical defect or a very unusual situation. If, on the other hand, the magnitude of the acceleration value is below the first limit value ah < 1, the first logic subunit 74a controls the first switch 80a so that it moves to its closed state. Figure 9a transitions.

[0034] The check described above is performed continuously. As long as the magnitude of the acceleration in the XY plane does not exceed the first limit value ah < 1, the first switch 80a remains closed. However, if the first limit value ah < 1 is exceeded, the first switch 80a opens, and the first emergency state is present. This means that, due to an acceleration in the XY plane, the electromagnet 42 is de-energized, thus locking the belt spool 20 against the housing 12. The step according to the invention now follows: After the switch has been opened, the first logic subunit 74a checks whether the magnitude of the acceleration in the XY plane |a XY | falls below a second limit value ah < 2, where this second limit value ah < 2 is smaller than the first limit value ah < 1. As long as this is not the case, the first switch 80a remains closed, and thus the first emergency state is maintained.Only when the magnitude of the acceleration in the XY plane |a XY | also falls below this second limit value ah < 2, is the first switch 80a closed again and the first emergency state no longer exists. Preferably, the second limit value ah < 2 is between 20% and 80% of the first limit value ah < 1.

[0035] The mechanical analogue is in the Figures 11a and 11b As shown: In order to move the ball from its minimum, the force acting on it in the radial direction R r must exceed a first limit so that it can climb the steeper ramp. It then reaches a flatter ramp, where it remains with a lower holding force acting in the radial direction.

[0036] Only when this falls below a second limit, which is smaller than the first limit, can the ball return to its starting position.

[0037] In parallel to what has just been described, the second logic subunit 74b continuously monitors the amount of the vehicle's tilt |ΔZ|. Here too, after starting, it can first be checked whether |ΔZ| exceeds a limit value G. If this is already the case when the vehicle starts, then an unusual condition or a technical defect must be assumed. If, on the other hand, |ΔZ| is less than the limit value G, then the second switch 80b is also closed, and the entire seatbelt retractor unit is in its enabled state. Figure 9a ) before.

[0038] The check to see if |ΔZ| exceeds the limit value G is also performed continuously. As long as this limit value is not exceeded, the second switch 80b remains closed; however, if it is exceeded, the second switch 80b opens, and the belt retractor unit is then in its second emergency state according to the definitions given here. Depending on whether the first emergency state is also present at the same time (which can be the case, but does not have to be), either the switching state of the Figure 9c or the switching state of the Figure 9d The enabled state exists due to the AND gate ( Figure 9a ) however, only if neither of the two emergency conditions are present.

[0039] If |ΔZ| falls below the limit value G again, the second switch closes. Hysteresis is not necessary here, but would also be possible.

[0040] The Figure 12Figure 2 shows a second embodiment of the left flowchart, i.e., the operation of the first logic subunit 54a: As can be seen, the sequence of functions is initially identical to that described above; however, after the second limit value ah < 2 is crossed, a further step follows before the first switch 80a is closed again. Specifically, a timer is started, and during a selected time interval Δt, for example, 500 or 1,000 ms, it is continuously checked whether the magnitude of the acceleration in the XY plane |a XY | exceeds a third limit value ah < 3. This third limit value ah < 2 can be identical to the first limit value ah < 1, but it can also lie between the first limit value ah < 1 and the second limit value ah < 2. As soon as a corresponding exceedance of the third limit value ah < 3 is detected, the time interval starts again from the beginning.Only when the third limit value ah< 3 is not exceeded in a continuous time interval Δt, is the first switch closed again, so that the belt retractor unit leaves its first emergency state.

[0041] The measures described ensure that a large number of switching cycles are avoided despite low limit values ​​for locking the belt spool. Reference symbol list

[0042] 10 Belt winder 12 Housing 14a,b Housing plate 16 Connecting bolt 18 Bracket for spring and actuator unit 20 Belt spool 22 Locking wheel 24 Lever 24a Locking pawl 30 Tension spring 40 Actuator unit 42 Electromagnet 44 Plunger 50 Control unit 55 Power input 56 Power output 60 Sensor unit 70 Switching unit 74 Logic unit 74a First logic subunit (acceleration evaluation in the XY plane) 74b Second logic subunit (tilt evaluation ΔZ) 80 Switching unit 80a First switch 80b Second switch

Claims

1. Belt retractor unit comprising a housing (12), a belt reel (20) rotatably mounted in said housing (12), a blocking unit for blocking the belt reel (20) against the housing (12), the blocking unit having an electrically activatable actuator unit (40), a control device (50) for activating the actuator unit (40), which has a sensor device (60) for continuously measuring at least one horizontal acceleration value and a switching device (70) for activating the actuator unit (40) depending on at least the at least one horizontal acceleration value, the belt retractor unit having a first emergency state in which the magnitude of the at least one horizontal acceleration value (|aXY|) is above a first limit value (ah1) and in which the belt reel (20) is blocked against the housing (12), and a release state in which the magnitude of the at least one horizontal acceleration value (|aXY|) is below the first limit value (ah1) and in which the belt reel (20) is not blocked against the housing (12), characterized in that the belt retractor unit does not transition from the first emergency state into the released state as long as the magnitude of the at least one horizontal acceleration value (|aXY|) has not dropped below a second limit value (ah2) which is less than the first limit value (ah1), and the belt retractor unit transitions from the first emergency state to the release state only when the magnitude of the at least one horizontal acceleration value (|aXY|) does not exceed a third limit value (ah3) again for at least a period of 250 ms.

2. Belt retractor unit according to claim 1, characterized in that, it transitions from the first emergency state to the release state only when the magnitude of the at least one horizontal acceleration value (|aXY|) does not exceed the third limit value (ah3) again for at least a period of 500 ms.

3. Belt retractor unit according to claim 1 or claim 2, characterized in that the third limit value (ah3) is greater than the second limit value (ah2) and is less than or equal to the first limit value (ah1).

4. Belt retractor unit according to any of claims 1 to 3, characterized in that the sensor device (60) furthermore measures its inclination (ΔZ) against the vertical axis and transmits it to the switching device (70), but this does not take into account the inclination (ΔZ) when determining the first emergency state.

5. Belt retractor unit according to claim 4, characterized in that the belt retractor unit has a second emergency state in which the inclination (ΔZ) exceeds an inclination limit value (G) and in which the belt reel (20) is blocked against the housing (12).

6. Belt retractor unit according to claim 5, characterized in that the second emergency state is independent of the magnitude of the horizontal acceleration value (|aXY|).

7. Belt retractor unit according to any of the preceding claims, characterized in that the sensor device (60) comprises a 3-axis sensor.