Seat belt retractor having an electrically actuatable locking device

Abstract

A seat belt retractor has a seat belt shaft and a control cam mounted thereon, and an electrically actuatable locking device (100) which stops the control cam (21) relative to the seat belt shaft (20) by engagement of the locking lever (2) into the tooth system (26) of the control cam (21), the locking lever (2) has a first arm (16) and thus forces a pawl to perform a movement in which the pawl is fixed to the vehicle and locks the seat belt shaft in the pull-out direction by means of a tooth system which engages with the seat belt retractor, and wherein the locking lever (2) has a lever arm (22) which projects outwards from the first arm (16) and which engages with the first arm (16) and thus forces the pawl to perform a movement in which the tooth system is fixed to the vehicle and locks the seat belt shaft in the pull-out direction. The locking lever (2) has a lever arm (23), on which a first end of a first spring (4) acts, which preloads the locking lever (2) into a position in which the locking lever engages with a locking tip (25) arranged at the end of the locking arm (23) into the tooth system (26) of the control cam (21). Furthermore, a projection (200) is provided on the housing (1) of the locking device, which projection is shaped such that the first spring (4) abuts against the projection independently of the position of the locking lever (2) and is transversely preloaded with respect to the spring force exerted on the lever arm (22).

Description

[0001] The invention relates to a seat belt having an electrically actuatable locking device having the features of the preamble of claim 1 .

[0002] An electrically actuatable locking device of this type is known from GB 2 398 824 A, for example.

[0003] Such a locking device serves to stop an externally toothed control cam, which is rotatably mounted on the seat belt shaft of the seat belt retractor, relative to the seat belt shaft by engagement of a locking lever and thus forces a locking pawl to execute a control movement into a tooth system which is fixed to the vehicle and thus in turn locks the seat belt shaft in the extension direction.

[0004] In conventional mechanical latching devices, an inertial mass is mounted on the contact surface, which deflects when a predetermined vehicle deceleration is exceeded, thereby deflecting a locking lever and forcing it to engage with the tooth system of a control cam. Such mechanical latching devices are also referred to as vehicle-sensitive sensor devices. One problem with these mechanical latching devices is that, regardless of the mounting geometry of the seat belt retractor, the inertial mass always has to be aligned in a defined orientation on the contact surface relative to the vehicle longitudinal axis and the vehicle transverse axis so that the seat belt shaft cannot be inadvertently latched. The seat belt retractor therefore has to be designed to be vehicle-independent, since the orientation of the contact surface relative to the seat belt retractor and the mass applied to this surface is designed independently so that it corresponds to a predetermined orientation, taking into account the mounting geometry of the seat belt retractor in the vehicle. Furthermore, in the case of seat belt retractors integrated in the front seats, such as in the case of convertibles, there is the problem that when the inclination angle of the backrest is adjusted or when the backrest is folded forward to access the rear seats, the inertial mass is unintentionally deflected towards the contact surface and the locking lever is thus unintentionally pushed into the external tooth system of the control cam for controlling the movement. As a result, the seat belt retractor is blocked in the extension direction and the backrest cannot be pivoted further or the occupant cannot fasten the seat belt. In order to prevent this, additional disconnection mechanisms or compensation mechanisms must be provided, which, however, may only function in these cases in order to ensure the restraint of the occupant in the event of an accident in all cases. Due to these aims, mechanical locking devices of this type are mechanically very complex.

[0005] In contrast, in the case of an electrically actuatable locking device, as known, for example, from GB 2 398 824 A, the movement of the locking lever is electrically controlled, thus omitting the previously required inertial mass. As a result, the seat belt retractor can be installed unchanged in different installation positions in the vehicle, also in the backrest. Furthermore, the locking of the seat belt shaft can be controlled by an electrical signal from a control device. In this case, the signal can be generated by the control device, which can also generate the signal depending on other sensor devices or control systems. For example, it is conceivable that the seat belt shaft is automatically locked when a dynamic assistance system is activated, which is controlled, for example, depending on the signal of an optical sensor device. Thus, depending on the signal of the optical sensor device, the electrical locking device is also controlled directly or indirectly. Furthermore, the electrically actuatable locking device is effective in any orientation and arrangement, since it is not actuated by inertial forces and therefore does not have to be oriented in a specific orientation relative to the direction of travel of the vehicle. It may therefore also preferably be arranged in seats of at least semi-autonomous vehicles, which seats can be adjusted by the occupants over a much greater adjustment range than is possible in seats of conventional non-autonomous vehicles, for improved communication with other occupants, for alignment in a stationary position, or generally also for taking advantage of the degrees of freedom gained by automated driving.

[0006] The electrically actuable locking device 100 used by the applicant in its products and corresponding to the embodiment of GB 2 398 824 A is Figure 1 and Figure 2 is shown as a separate component in Figure 3 1 is shown on a seat belt retractor. As basic elements, the electrically actuatable locking device 100 comprises: a housing 1, which has an L-shaped basic structure, comprising a base plate 15 and a first upright arm 16; a locking lever 2, which is pivotally mounted on the first upright arm 16 of the housing 1; an electromagnet 3; and a first spring 4, which is held on the housing 1 by one end and is connected by the other end to a lever arm 22 of the locking lever 2 protruding outwards from the first upright arm 16. The first spring 4 is designed as a tension spring, so that it preloads the locking lever 2 into a position in which the locking lever engages with the locking tip 25 in the tooth system 26 of the control cam 21 and thereby holds the control cam 21 relative to the seat belt shaft 20. The control cam 21 including the tooth system 26 is only in the Figure 3. In this way, when the seat belt shaft 20 rotates in the extension direction, the locking pawl is automatically pushed into the tooth system fixed to the vehicle and then locks the seat belt shaft 20 so that the seat belt cannot be pulled out further. The locking lever 2 includes a profile portion 24 and a steel plate 5, which faces the electromagnet 3, so that when the electromagnet 3 is energized, the locking lever 2 is attracted by the electromagnet and is therefore pulled out of the tooth system 26 of the control cam 21. Therefore, the seat belt shaft 20 can then rotate freely in the extension direction and the retraction direction. The advantage of this solution is that the seat belt shaft 20 is locked in the extension direction even in the event of a power failure or a failure of the electromagnet 3, and in this case, the occupant is also reliably restrained.

[0007] The electromagnet 3 comprises a base part 6, which comprises a cylindrical central part 7 and two radial flanges 8, one of which in each case projects radially outwards at one end of the central part 7. The electromagnet 3 is held on a base plate 15 of the housing 1 by means of the base part 6. The base part 6 has a tubular through-portion 14 in the central part 7 and, on the radially outer side of the central part 7, an annular intermediate space 9 which is delimited by the radial flanges 8 towards the end of the central part 7. Furthermore, the electromagnet 3 comprises a coil 10 with a plurality of windings, which is arranged in the annular intermediate space 9 and is in electrical contact with an external control device via a line 11 provided in the base part 6. Furthermore, the electromagnet 3 comprises a first core 12 which is arranged in the tubular through-portion 14 of the base part 6 and whose free end faces the steel plate 5 of the locking lever 2.

[0008] When the coil 10 is energized, the locking lever 2 is attracted because it closes the first magnetic circuit I, which is defined by the first upright arm 16 of the housing 1, the first iron core 12, and the portion of the locking lever 2 and the base plate 15 between the first iron core 12 and the first upright arm 16. Figure 2 In addition, a damping element 13 is provided in the form of an inherently flexible tube (e.g. in the form of a short piece of tubular material) which is clamped at its ends between two extensions of the radial flange 8 facing the locking lever 2. The damping element 13 is positioned so that the free end of the locking lever 2 in the deflected position ( Figure 2 The left side view in FIG. 1 does not abut against the damping element 13 and only in the attraction position ( Figure 2 The right side view in FIG. 2 (right side view in FIG. 2 ) abuts against the central soft part of the damping element 13 between the clamping points. As a result, the attraction movement of the locking lever 2 is damped in the final stage of the movement. As a result of this damping, a soft stop is achieved and disruptive "rattle noises" are avoided during the attraction movement and possible subsequent slight movements of the locking lever 2.

[0009] An object of the present invention is to provide a seat belt retractor of the generic type having reduced noise generation and a simplified basic structure.

[0010] To achieve this object, a seat belt retractor is proposed having the features of claim 1. Further preferred embodiments of the invention can be gathered from the dependent claims, the drawings and the associated description.

[0011] According to the basic idea of ​​the invention, it is proposed to provide a projection on the housing, which projection is shaped such that the first spring bears against it independently of the position of the locking lever and is preloaded laterally with respect to the spring force exerted on the lever arm.

[0012] The proposed solution additionally preloads the first spring and thus secures the first spring against uncontrolled movement, thereby reducing noise generated by preventing physical contact between the first spring and adjacent components of the locking device. The spring is preloaded independently of the position of the locking lever, so that the first spring is preloaded by the projection when the locking lever is in the deflected position (i.e. when the seat belt shaft is locked) and when the locking lever is retracted (i.e. when the seat belt shaft is released). The first spring abuts against the projection in such a way that it is preloaded laterally with respect to the spring force exerted by the first spring on the lever arm, so that the movement of the lever arm has no effect or only a minimal possible effect on the preload exerted by the projection on the first spring.

[0013] The decisive advantage of the proposed solution is that the movement behavior of the first spring, which triggers the movement of the locking lever, is immediately limited. This reduces the noise generated as close to the noise source and close to the housing as possible when the first spring is clamped on the locking lever. The preloading of the first spring not only leads to an increased clamping of the first spring when connected to the locking lever and the housing, but also reduces possible lateral movements of the first spring, thereby reducing the possibility of the first spring hitting adjacent components of the locking device and thus reducing the associated potential noise generation.

[0014] Furthermore, the first spring is held by the second end in the region of the base plate, and the projection is arranged on a first arm of the housing that projects upward from the base plate. Thus, the first spring extends laterally from the base plate to the lever arm of the locking lever on the locking device, so that the first arm provides a structurally easy-to-use surface laterally to the first spring and the projection can be arranged on this surface. Furthermore, the first spring provides an intermediate section in the region between the retainer on the lever arm and in a region of the base plate that is as long as possible and freely accessible, against which the projection can come into contact and via which the first spring can be loaded.

[0015] It is also proposed that the projection is molded onto an attachment part which is held on the housing. This means that the housing itself does not need to be modified, provided that it already has a sufficient attachment surface for fastening the attachment part. Furthermore, the attachment part can be shaped separately to form the projection and can be aligned when fastened in such a way that the first spring automatically comes into contact with the blocking device due to its fastening and is preloaded according to the invention.

[0016] The attachment part can preferably have a retaining attachment arranged in the area of ​​the base plate, and the first spring can be retained on the retaining attachment with its second end. Therefore, the attachment part is also used for the second end of the fastening spring, which provides the following advantages: the first spring for its second end of the projection and the fastening attachment are realized on the same part and are therefore arranged in a fixed spatial relationship to each other. In addition, the housing does not have to be designed to form a projection or to attach the second end of the spring, as long as it only has an attachment surface for the attachment part. The attachment part is particularly designed so that the retaining attachment is arranged in the area of ​​the base plate of the housing. This allows the first spring to be made as long as possible and to be arranged to use the entire free space between the locking lever and the base plate.

[0017] The retaining attachment can preferably be designed to extend the base plate outwards. Therefore, the retaining attachment forms an extended lug of the base plate, so that the fastening points of the first spring on the lever arm of the locking lever and on the retaining attachment can be formed opposite each other, thereby forming a free space between them.

[0018] It is also proposed that the first spring is formed by a cylindrical helical spring and that the projection deflects the first spring laterally transversely to the longitudinal extension of the first spring. The proposed design of the first spring offers the advantage that the first spring is preloaded by deflecting it laterally without losing its desired properties with respect to preloading the lever arm of the locking lever. In this case, the first spring is preloaded by the projection transversely to the spring force it exerts on the lever arm, which has the advantage that the preloading of the first spring via the projection is deliberately not directed or only partially directed in the direction in which the spring force is exerted on the lever arm, so that the spring force exerted by the first spring on the lever arm is never reduced and, if possible, is increased.

[0019] It is also proposed that the projection is formed by a cam with a curved contact surface. The first spring is preloaded by the projection and thus has a curved shape. The projection is adapted to this curved shape of the first spring by its curved contact surface so that the first spring is pushed into the preloaded shape as gently as possible by the projection and the force is as localized as possible. To this end, when the contact surface contacts the projection, the contact surface is curved in the same direction as the curvature of the first spring.

[0020] It is further proposed that the first spring has an elastic plastic sheath at least in the area in contact with the protrusion. The elastic plastic sheath can further reduce the noise generated when the first spring moves toward the protrusion by suppressing the noise when the first spring contacts the elastic plastic sheath. In addition, the first spring can be protected from external mechanical influences.

[0021] The present invention is explained below based on preferred embodiments with reference to the accompanying drawings. In the accompanying drawings:

[0022] Figure 1 is an exploded view of an electrically actuatable locking device according to the prior art; and

[0023] Figure 2 is a cross-sectional view of an electrically actuatable locking device according to the prior art, the locking device having a locking lever in two different positions; and

[0024] Figure 3 It is based on the existing technology Figure 1 and Figure 2 A seat belt retractor having a locking device and a released seat belt shaft; and

[0025] Figure 4 is a perspective view of a locking device further developed according to the present invention; and

[0026] Figure 5 is a side view of a locking device further developed according to the present invention; and

[0027] Figure 6 is a cross-sectional view of a locking device further developed according to the present invention; and

[0028] Figure 7 It is a locking device further developed according to the present invention, without a locking lever.

[0029] exist Figures 4 to 6 In FIG. 1 , a further developed electrical locking device 100 can be seen, which is Figure 3 The seat belt retractor replaces Figure 1 to Figure 2 The locking device 100 is provided in the embodiment of the present invention to realize the seat belt retractor according to the present invention. Figures 4 to 5 The locking device 100 and Figure 1 and Figure 2 The locking device 100 is different in that a second upright arm 17 is additionally provided on the base plate 15 of the housing 1. When the locking lever 2 is pulled, the second upright arm closes the second magnetic circuit II via the first upright arm 16 according to the same principle as the first magnetic circuit I, so that the attraction force of the locking lever 2 can be increased. For this purpose, instead of Figure 1 and Figure 2In the locking device 100, two separate cores 12a and 12b are provided. In addition, the damping element 13 has been omitted here, but it can also be additionally provided if the generation of noise and the movement behavior of the locking lever 2 are to be further suppressed. In addition, a second spring (not shown) can be additionally provided, which acts directly on the locking arm 23 and is positioned so that when the locking lever 2 is pulled towards the housing 1, the second spring is preloaded and supports the pivoting movement of the locking lever 2, thereby shortening the locking time of the seat belt shaft 20. In addition, the locking lever 2 can thereby be further tensioned, so that its uncontrolled movement can be further reduced.

[0030] according to Figures 4 to 6 A further improved locking device 100 comprises a protrusion 200 which abuts laterally against the first spring 4 and forces the first spring into a bent position. The protrusion 200 loads the first spring transversely to the longitudinal extension direction of the first spring 4. The protrusion 200 is formed on an attachment part 203 which is attached laterally to the first upright arm 16 of the housing 1. The attachment part 203 is a plastic part, preferably an elastomer, preferably of the Hytrel type, and is shaped to extend to the base plate 15 of the housing 1. The attachment part 203 also comprises a retaining attachment 202 which protrudes outwardly from the housing 1 of the locking device 100 in the same direction as the lever arm 22 of the locking lever 2. The retaining attachment 202 is positioned so that it extends the base plate 15 of the housing 1 outwardly and thus forms an abutment opposite to the lever arm 22. The first spring 4 is implemented by a cylindrical helical spring, the first end (upper end in the figure) of which is fixed to the lever arm 22 of the locking lever 2, and the second lower end of which is fixed to the retaining attachment 202. The first spring 4 is designed so that in the fastened position, it exerts tension on the lever arm 22 and thereby preloads the locking lever 2 to the position in which it is engaged. Figures 4 to 6The position shown. At the same time, the first spring rests laterally on the curved contact surface 201 of the protrusion 200 and is thereby bent laterally and is additionally preloaded laterally relative to the tension exerted by the first spring on the lever arm 22. Due to the helical shape of the first spring 4, the tension exerted by the first spring 4 on the lever arm 22 is applied in the direction of its longitudinal axis. The protrusion 200 rests laterally on the first spring 4 and deforms the first spring 4 orthogonal to its longitudinal direction. This additionally loads the first spring 4 and further increases the tension acting in the first spring 4. This additionally tensions the first spring 4 and increases the tension exerted on the lever arm 22. Due to the deformation of the first spring 4 caused by the protrusion 200, the first spring abuts against the curved contact surface 201 of the protrusion 200, regardless of the position of the locking lever 2, and can therefore not perform or only perform a very slight noise-causing movement towards the locking device 100. Furthermore, the attachment part 203 extends to the base surface 15 of the housing 1 and forms, together with the retaining attachment 202, an abutment which is arranged in the region of the base surface 15 of the housing 1 and to which the first spring 4 is fastened with its second end. This allows the use of a first spring 4 having the greatest possible length.

[0031] The protrusion 200 is realized on an attachment part 203 fastened to the housing 1, so that the housing 1 does not require any special shaping to realize the protrusion 200, except for fastening the attachment part 203. In addition, the protrusion 200 is provided with a curved contact surface 201, the curvature of which is aligned with the curvature of the first spring 4 in the contact area of ​​the protrusion 200, so that the protrusion 200 abuts against the curved first spring 4 with an enlarged surface. In addition, the protrusion 200 can be realized on the attachment part 203 by a material different from that of the housing 1. In order to realize the magnetic circuits I and II, the housing 1 is preferably made of a magnetic material, preferably a ferromagnetic metal, while the attachment part 203 is formed here by a plastic, preferably an elastomer of the Hytrel type, which has the necessary dimensional stability for the deflection of the first spring 4 and at the same time has damping properties with respect to the generation of noise due to its elastic properties.

[0032] Furthermore, the first spring 4 can additionally be provided with an elastic plastic sheath, wherein the generation of noise can be further reduced.

[0033] exist Figure 7, a further improved locking device 100 is shown without the locking lever 2. The upper radial flange 8 is additionally provided with an upwardly protruding lug 27, which is arranged centrally on the side edge of the radial flange 8 facing the second upright arm 17 and has an elongated shape aligned parallel to the side edge. Furthermore, the first upright arm 16 is provided with two upright lugs 18 and 19 spaced apart from each other. The lugs 18 and 19 on the first upright arm 16 and the lug 27 on the radial flange 8 together form a three-point support for the locking lever 2 in the retracted position, so that the locking lever 2 cannot perform any tilting movement in the retracted position.

Claims

1. A seat belt retractor, the seat belt retractor having - a rotatably mounted seat belt shaft (20), and - a toothed control cam (21) rotatably mounted on the seat belt shaft, and - an electrically actuatable locking device (100), comprising - a housing (1) having a base plate (15) and a first upright arm (16), and - a locking lever (2) which is pivotally mounted in a pivot bearing of the first upright arm (16) and comprises a steel plate (5), wherein - the electrically actuatable locking device (100) stops the control cam (21) relative to the seat belt shaft (20) by the locking lever (2) engaging in the tooth system (26) of the control cam (21), thereby forcing a locking pawl to perform a movement for engaging in the tooth system of the seat belt retractor, the tooth system being fixed to the vehicle, locking the seat belt shaft in the extension direction, and wherein - the locking lever (2) has a lever arm (22) which projects outwards from the first arm (16) and on which a first end of a first spring (4) acts, the first spring preloading the locking lever (2) into a position in which the locking lever engages with a locking tip (25) arranged at the end of the locking arm (23) in the tooth system (26) of the control cam (21), and an electromagnet (3) which is arranged in the housing (1) and which, by energizing the locking lever (2), exerts a force on the locking lever (2), by means of which the locking lever together with the locking tip (25) is pulled out of the tooth system (26) of the control cam (21), It is characterized in that A projection (200) is arranged on the housing (1) and is shaped such that the first spring (4) bears against the projection independently of the position of the locking lever (2) and is laterally preloaded relative to the spring force exerted on the lever arm (22).

2. The seat belt retractor according to claim 1, characterized in that: - the first spring (4) is held with its second end in the region of the base plate (15), and The protrusion (200) is arranged on the first arm (16) of the housing (1), the first arm protruding upward from the base plate (15).

3. The seat belt retractor according to claim 1 or claim 2, characterized in that: - The protrusion (200) is molded onto an attachment part (203), which is retained on the housing (1).

4. The seat belt retractor according to claim 3, characterized in that: - the attachment component (203) has a retaining attachment (202) which is arranged in the region of the base plate (15), and - The first spring (4) is retained with its second end on the retaining attachment (202).

5. The seat belt retractor according to claim 4, characterized in that: - The retaining attachment (202) extends the base plate (15) outwards.

6. The seat belt retractor according to any one of claims 1 to 5, characterized in that: The first spring (4) is formed by a cylindrical helical spring, and the protrusion (200) is transverse to the longitudinal extension of the first spring (4) to deflect the first spring laterally.

7. The seat belt retractor according to any one of claims 1 to 6, characterized in that: - The protrusion (200) is formed by a cam having a curved contact surface (201).

8. The seat belt retractor according to any one of claims 1 to 7, characterized in that: - The first spring (4) has an elastic plastic sheath at least in the region in contact with the projection (200).

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