The invention relates to a belt retractor for a vehicle safety belt, with a frame, a belt spool which can receive a safety belt and is arranged rotatably in the frame, and with a blocking mechanism by means of which the belt spool can be blocked against a rotation in the safety belt unwinding direction relative to the frame, the blocking mechanism containing a coupling disc which is rotatable relative to the belt spool.
The blocking mechanism serves in a known manner to block the belt spool in a vehicle-sensitive or belt band-sensitive manner. A vehicle-sensitive blocking is triggered when the accelerations acting on the vehicle and therefore also on the belt retractor, which is mounted therein, exceed a specified value. A belt band-sensitive blocking is triggered when the rotary acceleration of the belt spool, brought about by a rapid withdrawal of the safety belt from the belt spool, exceeds a specified value. In both cases, the blocking is triggered in that a relative rotation occurs between the coupling disc and the belt spool, which is then used to guide a blocking catch into blocking teeth.
With the vehicle-sensitive blocking, a sensor is used which, on exceeding the specified acceleration, blocks the coupling disc. If, in this state, safety belt is withdrawn from the belt spool, the coupling disc—because it is secured by the sensor—lags behind the rotation of the belt spool, so that the necessary relative rotation is obtained for guiding the blocking catch. With the belt band-sensitive blocking, the mass moment of inertia of the coupling disc is used to bring about the relative rotation; with a sufficiently high rotary acceleration of the belt spool, the coupling disc lags behind the rotation of the belt spool, whereby the blocking catch can be guided in.
The blocking mechanism, however, also possibly responds in situations in which this is not desired. In particular with the rapid winding of the belt band, for example when a vehicle occupant has taken off the safety belt and the safety belt is rolled up under the action of a winding spring, it can occur that the blocking mechanism responds. This is the case in particular when the safety belt is braked abruptly, for example when an insert tongue, situated on the safety belt, butts against another component or the safety belt is fully wound, whereby the belt spool is braked abruptly. Through the abrupt braking, a relative rotation can occur between the coupling disc and the belt spool, so that the blocking mechanism responds. In addition, the risk exists that through vibrations, the sensor on the belt retractor responds, whereby a vehicle-sensitive blocking can be triggered.
If belt band is then to be withdrawn from the belt spool, the belt spool is blocked by the blocking mechanism. A vehicle occupant could therefore gain the impression that the belt retractor is defective. The blocking of the belt spool can then only be released by pulling firmly on the safety belt, so that through the film spool effect a small length of safety belt can be withdrawn. In the subsequent freeing of the safety belt, the belt spool is turned back slightly, whereby the blocking mechanism is unlocked.
Various precautions are known from the prior art, in order to prevent the undesired blocking of the belt spool at the end of the winding movement. These precautions, however, do not always work satisfactorily; this applies both to their function and also to the effort.
The object of the invention consists in further developing a belt retractor of the type initially mentioned to the effect that an undesired blocking of the belt spool at the end of the winding of the safety belt is reliably prevented.
To solve this problem, in a belt retractor of the type initially mentioned in accordance with the invention a locking mechanism is provided which locks a response of the blocking mechanism in a function range in which almost the entire safety belt is wound on the belt spool. The locking mechanism here can neutralize the vehicle-sensitive blocking and/or the belt band-sensitive blocking of the belt spool in line with specific objectives.
According to a preferred embodiment of the invention, provision is made that the blocking mechanism has a vehicle-sensitive sensor with a sensor lever, which can engage on the coupling disc, and that the locking mechanism, when it is activated, locks the sensor lever so that the latter can not engage on the coupling disc. In this way, it is reliably prevented that the vehicle-sensitive sensor responds and thereby blocks the coupling disc, which could lead to a vehicle-sensitive blocking of the belt spool.
According to a preferred embodiment of the invention, provision is made that the locking mechanism, when it is activated, locks the coupling disc so as to be secure with regard to rotation with respect to the belt spool. This prevents a relative rotation between the coupling disc and the belt spool, so that any response of the blocking mechanism is reliably prevented. In particular, a belt band-sensitive response is not possible, because also with an abrupt acceleration or deceleration of the belt spool, the coupling disc is directly entrained, so that no relative rotation is possible between the coupling disc and the belt spool and accordingly also no response of the blocking mechanism is possible.
Advantageous developments of the invention will be apparent from the sub-claims.
The invention is described below with the aid of a preferred embodiment which is illustrated in the enclosed drawings. In these:
Figure 11 shows a detail of the locking mechanism, the locking lever being situated in the initial position; and
In
A blocking mechanism is provided, which serves to block the belt spool so as to be secure with regard to rotation relative to the frame 12 in case of necessity. The details of the structure and mode of operation of the blocking mechanism are described below only in so far as they are necessary for an understanding of the invention. An essential component of the blocking mechanism is a coupling disc 16, which is arranged coaxially with the belt spool and is rotatable relative thereto to a limited extent. Through a relative rotation between the coupling disc 16 and the belt spool 14, a blocking catch (not illustrated), which is arranged in a recess 18 on the end face of the belt spool 14, is guided into blocking teeth on the frame 12 of the belt retractor 10. Such a relative rotation can be brought about in a belt band-sensitive manner or in a vehicle-sensitive manner. For a vehicle-sensitive controlling of the blocking mechanism, a sensor 20 is arranged on the frame of the belt retractor, which has a sensor ball 22 and a sensor lever 24. The sensor lever 24 can be guided into teeth 26 of the coupling disc 16, so that the coupling disc 16 is blocked against a rotation in the unwinding direction of the safety belt. When the safety belt is withdrawn from the belt spool, the coupling disc 16 remains at a standstill. The relative rotation resulting therefrom between the belt spool and the coupling disc is used to control the blocking catch.
A locking disc 28 is provided, which is likewise arranged concentrically with the belt spool. The locking disc 28 is mounted rotatably on a housing part (not illustrated), which is arranged on the frame 12 of the belt retractor 10. The locking disc 12 is connected with the belt spool 14 by a reduction, which consists of a pinion 29 constructed on the belt spool 14, a two-stage reduction gear wheel 30, which is mounted so as to be stationary with respect to the frame 12 of the belt retractor, and of inner teeth 32 which are constructed on the locking disc 28 and extend over approximately 270 degrees. The reduction reduces the rotation of the belt spool 14 to such a great extent that the locking disc 28 carries out a rotation of a maximum of 270 degrees between a state of the belt retractor with fully wound safety belt on the one hand and with fully unwound safety belt on the other hand.
A child safety lever 34 is provided, by means of which a child safety function can be achieved. When the child safety function is activated, no belt band can be unwound from the belt retractor; it is merely possible to wind the belt band. Such a function is desirable, for example, in order to fix a child's seat securely to the vehicle seat. The child safety function is realized in a manner known per se by two trip cams 36, 37 on the locking disc 28, which as a function of the position of the locking disc 28 can adjust the child safety lever between an initial position in which it does not engage on the teeth 26 of the coupling disc 16, and an activated position in which it blocks the coupling disc 16, so that on withdrawal of the safety belt a belt band-sensitive blocking is triggered immediately. The two trip cams 36, 37 are arranged here so that the child safety function is activated by almost complete withdrawal of the safety belt from the belt spool and is deactivated again by almost complete winding of the safety belt.
A locking mechanism is provided, by means of which, as a function of the position of the locking disc 28, the response of the blocking mechanism can be prevented. The locking mechanism contains, on the one hand, a locking lever 38, which is arranged in fixed position relative to the frame 12 of the belt retractor and is able to be swivelled between two positions about a bearing 39, namely an initial position (see
On the side facing away from the locking extension, the locking lever 38 is provided with two guide pins 42, which together with a guide rib 44 form a connecting link guide on the locking disc 28. The guide rib 44 extends along the periphery of the locking disc 28 and consists of a section arranged radially further outwards and of a section arranged radially further inwards. Between these two sections, a transition section 46 is arranged (see in particular
The locking mechanism on the other hand contains a bolt 48 (see in particular
To move the bolt 48, a control pin 54 is provided at its free end, which cooperates with a link which is formed by two control ribs 56, 57 lying opposite each other, which are constructed on the locking lever 38 opposite the two guide pins 42, i.e. likewise at the end facing away from the locking extension 40.
In the normal operation of the belt retractor, the bolt 48 is in the initial position shown in
As soon as a specified length of the safety belt is unwound from the belt spool, firstly, brought about by the guide rib 44, the locking lever 38 is transferred from its locking position into the initial position. As soon as the bolt 48 together with its control pin 54 then passes the two control ribs 56, 57 of the locking lever 38 the next time, the control pin 54 is pressed radially outwards from the control ribs, whereby the bolt 48 is transferred into its initial position. Thereby, after the sensor 20 has firstly been freed again, the coupling disc 16 is also freed, so that the blocking mechanism can operate again as usual.
Through the positioning of the transition section 46 on the locking disc 28 with regard to angle, a setting can be made as to the length of the wound safety belt after which the usual finction of the blocking mechanism is prevented, i.e. firstly the sensor 20 and then the coupling disc 16 are inactivated.
According to a simplified embodiment of the invention, the bolt 48 is dispensed with.
Number | Date | Country | Kind |
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103 60 032.9 | Dec 2003 | DE | national |