U.S. patent application number 09/726666 was filed with the patent office on 2001-11-08 for belt retractor system.
Invention is credited to Durrstein, Rolf, Peter, Cornelius.
Application Number | 20010037907 09/726666 |
Document ID | / |
Family ID | 7930989 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010037907 |
Kind Code |
A1 |
Peter, Cornelius ; et
al. |
November 8, 2001 |
Belt retractor system
Abstract
A belt retractor for an occupant restraint system comprises a
frame, a belt reel rotatably mounted in the frame, an electric
motor drive coupled to the belt reel, a locking mechanism for
selectively blocking the belt reel, and a vehicle-sensitive sensor.
The locking mechanism is actuated by an actuator. An electronic
control unit is provided with an input interface and an output
interface. The vehicle-sensitive sensor is connected to the input
interface, and the actuator and the electric motor drive are
connected to the output interface.
Inventors: |
Peter, Cornelius; (Buhl,
DE) ; Durrstein, Rolf; (Bietigheim, DE) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL, TUMMINO & SZABO L.L.P.
1111 LEADER BLDG., 526 SUPERIOR AVENUE
CLEVELAND
OH
44114-1400
US
|
Family ID: |
7930989 |
Appl. No.: |
09/726666 |
Filed: |
November 29, 2000 |
Current U.S.
Class: |
180/268 |
Current CPC
Class: |
B60R 21/0155 20141001;
B60R 2022/4666 20130101; B60R 2021/01272 20130101; B60R 22/44
20130101; B60R 2022/3421 20130101; B65G 2207/18 20130101; B60R
22/415 20130101; B60R 21/01548 20141001; B60R 2021/01311 20130101;
B60R 2022/4473 20130101; B60R 22/46 20130101; B60R 22/343 20130101;
B65G 2201/02 20130101 |
Class at
Publication: |
180/268 |
International
Class: |
B60R 021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 1999 |
DE |
199 57 814.1 |
Claims
1. A belt retractor for an occupant restraint system, comprising: a
frame, a belt reel rotatably mounted in said frame, a locking
mechanism for selectively blocking said belt reel, a
vehicle-sensitive sensor, an actuator for actuating said locking
mechanism, an electric motor by which said belt reel is drivable,
an electronic control unit including an input interface and an
output interface, said vehicle-sensitive sensor being connected to
said input interface, and said actuator and said electric motor
being connected to said output interface.
2. The belt retractor as set forth in claim 1, comprising a storage
module assigned to said control unit and in which the program data
determined the functioning of said control unit is stored at least
in part.
3. The belt retractor as set forth in claim 1, wherein said
actuator is formed by an electromagnet driving a locking pawl of
said locking mechanism.
4. The belt retractor as set forth in claim 3, wherein said control
unit signals said electric motor so as to provide a belt tensioning
when the signal constellation of a plurality of sensors connected
to said input interface indicates an imminent vehicle
collision.
5. The belt retractor as set forth in claim 4, wherein said
electric motor is a brushless four-phase DC motor.
6. The belt retractor as set forth in any of the claim 4 wherein
said electric motor comprises a bifilar stator winding.
7. The belt retractor as set forth in any of the claim 4, wherein
said electric motor comprises an outside rotor having a neodymium
magnetic ring.
8. The belt retractor as set forth in claim 7, wherein said
electric motor comprises a 14-pole outside rotor.
9. The belt retractor as set forth in any of the claim 8, wherein
said electric motor is coupled by a toothed belt to said belt
reel.
10. The belt retractor as set forth in claim 9, wherein said
toothed belt couples a drive pinion of said electric motor to a
gearwheel side-mounted on said belt reel, said gearwheel having a
diameter larger than that of said drive pinion.
11. The belt retractor as set forth in claim 10, wherein said
electric motor is supported on a support plate side-mounted to a
leg of said frame so as to be capable of pivoting to a limited
extent and, by pivoting of said support plate, said toothed belt
can be pressed in a section between said gearwheel and said drive
pinion against a tensioning pulley mounted on said leg of said
frame.
12. The belt retractor as set forth in claim 11, wherein said
support plate is biased by a spring into a pivoted position in
which said tensioning pulley is spaced away from said toothed belt
and, with the tensile stress occurring in said toothed belt when
loaded, said support plate is moved automatically and to an extent
which depends on the load into an opposed pivoted position in which
said tensioning pulley presses against said toothed belt.
13. The belt retractor as set forth in claim 11, wherein said
electric motor is grouped together with a printed circuit board
into an assembly unit, said printed circuit board mounting an
electronic signaling circuit comprising power semiconductor
components.
14. The belt retractor as set forth in any of the claim 13
comprising sensors assigned to said electric motor, said sensors
providing signals from which an absolute angle of rotation of said
belt reel corresponding to the withdrawn belt webbing length can be
determined by said control unit.
15. The belt retractor as set forth in any of the claim 14 wherein
said control unit for signaling said electric motor takes into
account at least one, preferably several, of the following sensor
signals: ABS signal, braking pressure signal, acceleration signal,
vehicle speed signal, engine speed signal, belt force signal,
absolute belt reel angle of rotation.
16. The belt retractor as set forth in claim 14, wherein said
control unit loads said belt reel via said electric motor with a
permanent retraction moment, the value of which can be varied
across said absolute angle of rotation of said belt reel.
17. The belt retractor as set forth in claim 15, wherein said
control unit loads said belt reel via said electric motor with a
permanent retraction moment, the value of which can be varied
across said absolute angle of rotation of said belt reel.
18. An occupant restraint system for vehicles, comprising a
plurality of belt retractors, each belt retractor comprising: a
frame, a belt reel rotatably mounted in said frame, a locking
mechanism for selectively blocking said belt reel, a
vehicle-sensitive sensor, an actuator for actuating said locking
mechanism, an electric motor by which said belt reel is drivable,
an electronic control unit including an input interface and an
output interface and a program memory, said vehicle-sensitive
sensor being connected to said input interface; said actuator and
said electric motor being connected to said output interface; the
functionality of each belt retractor being dictated by program data
stored in said program memory of the corresponding control unit,
and at least two of said belt retractors having a different
functionality.
Description
FIELD OF INVENTION
[0001] The invention relates to a belt retractor for an occupant
restraint system.
BACKGROUND OF THE INVENTION
[0002] In addition to the usual belt webbing and/or
vehicle-sensitive locking functions modern belt retractors are
equipped with additional functions where necessary. One of these
additional functions is safeguarding loads or child seats by a
state of blockage which is activated by complete unwinding and
subsequent retraction of the belt webbing. Switching back into the
locking condition in case of an emergency is achieved by complete
retraction of the belt webbing. Another additional function is a
belt fastening detection for which the withdrawn belt webbing
length is determined.
[0003] Such additional functions of a belt retractor necessitate a
high complexity of mechanical components. Particularly complex is
to provide different types of belt retractors for the respective
additional functions requested.
BRIEF SUMMARY OF THE INVENTION
[0004] This is achieved in a belt retractor for an occupant
restraint system comprising a frame, a belt reel rotatably mounted
in the frame, an electric motor drive coupled to the belt reel, a
locking mechanism for selectively blocking the belt reel, and a
vehicle-sensitive sensor. The locking mechanism is actuated by an
actuator. An electronic control unit is provided with an input
interface and an output interface. The vehicle-sensitive sensor is
connected to the input interface, and the actuator and the electric
motor drive are connected to the output interface.
[0005] The invention provides a novel belt retractor having a
uniform mechanical basic design enabling a series of additional
functions to be achieved when requested.
[0006] Instead of the conventional retraction spring the belt
retractor according to the invention provides an electric motor
instead of the conventional retraction spring which loads the belt
reel with the retraction torque required in each case. The
functions of the belt retractor are controlled by an electronic
control unit including an input interface and an output interface.
The vehicle-sensitive sensor is connected to the input interface
and the actuator is connected to the output interface, as is the
electric motor. This basic concept facilitates the adaption of the
locking and retraction functions of the belt retractor to the
respective requirements, since merely program data need to be
adapted, according to which the electronic control unit works.
Furthermore, various sensors can be connected to the input
interface of the electronic control unit, the output signals of
which are taken into account in driving the locking mechanism.
Likewise further actuators or positioners and the like may be
connected to the output interface of the electronic control unit,
the functions of which are controlled in dependence of the sensor
signals as polled via the input interface of the electronic control
unit.
[0007] In the preferred embodiment the belt retractor includes an
electric motor, more particularly a servo motor, which not only
carries out the task of the retraction spring in a conventional
mechanical belt retractor but also can ensure a pretension of the
belt webbing in an imminent vehicle crash.
[0008] One of the sensors connected to the input interface yields
in the preferred embodiment an incremental signal representing the
rotation of the belt reel, preferably in conjunction with a further
signal indicating the sense of rotation. These signals are analyzed
by the electronic control unit by up/down counting to determine the
absolute angle of rotation of the belt reel and thus the length of
the belt webbing withdrawn.
[0009] In this preferred embodiment the belt retractor has the
following functions, some of which may also be achieved only when
required:
[0010] child seat/load safeguarding
[0011] belt fastening detection
[0012] vehicle-sensitive blocking
[0013] retraction spring
[0014] comfort gearing
[0015] blocking on non-locked seatback
[0016] belt webbing-sensitive blocking
[0017] belt webbing pretensioning.
[0018] On the basis of a uniform electromechanical basic concept,
numerous embodiments, differing in terms of functionality, can be
provided with the belt retractor system according to the invention.
The functionality is essentially determined by the sensors
connected to the input interface of the electronic control unit and
by the unerasably stored program according to which the control
unit operates.
[0019] The preferred embodiment provides additional functions which
can not be realized in conventional belt retractors. One of these
additional functions is the precautionary tensioning of the belt
webbing in a critical situation, e.g. a full braking. By making use
of a high-performance electric motor drive a tensioning force of
250 N or more is possible. A tensioning travel of 120 mm or more
for a tensioning time of only about 120 ms is realistic. Such
pretensioning enables the belt slack to be eliminated already prior
to an accident to minimize the risk of injury of the vehicle
occupants and to optimize the effectiveness of the conventional
belt tensioner, in particular the pyrotechnic-type belt
tensioner.
[0020] Belt webbing pretensioning may also be used to correct the
sitting posture of a vehicle occupant to minimize the risk of
injury by inflatable restraint means (air bag).
[0021] When, following a belt webbing pretensioning, normal driving
conditions reoccur, belt tensioning can be reversed.
[0022] On the other hand, after pretensioning of the belt webbing
and subsequent release have occurred, a renewed pretensioning of
the belt webbing is possible.
[0023] In the preferred embodiment the electric motor is coupled by
a toothed belt to a gearwheel side-mounted to the belt reel, the
gearwheel having a diameter larger than that of the drive pinion of
the electric motor. The toothed belt is set under tension by a belt
tightener as a function of the load. In normal operation the belt
tension is small, so that the drive works extremely silent and with
low wear. On tensioning of the belt webbing, the belt tension is
increased in order to assure a transmission of force without
skipping of teeth. At the same time, there is achieved an optimum
balance in terms of tooth clearance and tolerances.
[0024] The electric motor employed is preferably a low-wear,
brushless four-phase motor, its bifilar stator winding achieving
low commutating losses. Using a motor with an outside rotor a
compact design is achieved. The outside rotor carries preferably a
14-pole neodymium magnetic ring to enable a high drive moment in
line with a compact design, particularly in a short-time overload
operation. Two Hall sensors yield the rotor position, the sense of
rotation and, from this, the length of belt webbing withdrawn.
[0025] The locking mechanism of the belt retractor consists of an
apertured disk on the flange of the belt reel and a latching pin
mounted axially shiftable and spring-loaded at the frame of the
retractor, that pin being selectively latched in the holes of the
apertured disk of the belt reel. This engagement of the latching
pin in the holes of the apertured disk is facilitated by lead-in
ramps adjacent to the holes. The latching pin is maintained in the
nonactivated resting position by an electromagnet. In the
nonenergized condition the latching pin is moved into the locked
position by the spring loading.
[0026] The electronic control unit of the belt retractor meets more
particularly the following requirements:
[0027] motor commutation;
[0028] torque control;
[0029] overload protection:
[0030] drive of the belt reel release;
[0031] control of all comfort and safety functions;
[0032] continual computation of the actual belt withdrawal length
via the absolute angle of rotation of the belt reel;
[0033] input signals of the various connected sensors, discretely
and via a connected bus system (CAN):
[0034] fast 8-bit control unit with idle mode and integrated
EEPROM;
[0035] stator integrated on printed circuit board.
[0036] In the preferred embodiment of a vehicle occupant restraint
system all belt retractors have the same electromechanical basic
design and differ only in their functionality determined
substantially by the program data stored in the electronic control
unit. Thus, for example, the functionality of the front belt
retractors differ from those of the rear belt retractors. The
electronic control units of all belt retractors may be linked to a
common central sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Further features and advantages of the invention will become
apparent from the following description of a preferred embodiment
and from the accompanying drawings to which reference is made and
in which:
[0038] FIG. 1 is a block diagram of the electronic control unit of
the belt retractor;
[0039] FIG. 2 is a perspective overall view of the belt retractor
including an electric motor drive;
[0040] FIG. 3 is an exploded view of the belt retractor of FIG.
2;
[0041] FIG. 4 is a side view of the belt retractor with the
electric motor drive removed; and
[0042] FIG. 5 is a schematic axial section of electric motor with
drive pinion.
DETAILED DESCRIPTION OF THE INVENTION
[0043] The block diagram of FIG. 1 shows an electric motor 10 which
is an outside rotor having a neodymium magnetic ring. The outer
rotor is designed preferably so as to be 14-pole. Further, the
electric motor 10 is a brushless four-phase DC motor, the stator
winding of which is designed bifilar. Adjacent the outside rotor
are arranged two Hall sensors 12, 14. With these Hall sensors 12,
14, the rotation of the outside rotor is detected incrementally,
the sense of rotation being also detected, so that an absolute
angle of rotation can be determined. A microcomputer 16 receives
amongst the signals from the Hall sensors 12, 14 a plurality of
switching signals via an interface 18 and is furthermore coupled
bidirectionally via a transceiver 20 with a CAN bus. The current
supply is delivered to the microcomputer 16 via a voltage regulator
22 from the onboard voltage U.sub.B a t. The microcomputer 16
signals the stator windings 10a and 10b of the electric motor 10
via a driver circuit 24. The driver circuit 24 comprises
high-performance semiconductor power switches of the type FET,
which have an extremely low volume resistance and can therefore be
directly mounted onto a printed circuit board. Via a further driver
circuit 26, the microcomputer 16 signals the magnetic coil 28 of an
electromagnet, which actuates a latching mechanism of the belt
retractor described below.
[0044] The belt retractor has a substantially U-shaped frame 30
with parallel legs between which a belt reel 32 is rotatably
mounted. Rotation of the belt reel 32 in the frame 30 can be
blocked in a load-bearing manner by a locking pawl, a locking pin
or some of these elements. The locking pawl or the locking pin is
actuated by an electromagnet 34. This electromagnet 34 has the
magnetic coil 28 shown in FIG. 1.
[0045] A toothed belt disc 36 is non-rotatably coupled with the
belt reel 32. At the outer side of a leg of the frame 30, a support
plate 38 is mounted for limited rotation about the axle of the belt
reel 32. For limiting the pivoting movement of the support plate
38, the latter is provided with two oblong holes 40 which are
engaged by two pins 42 anchored to the frame 30. The support plate
38 mounts a bearing pin 44 on which the outside rotor 48 of the
electric motor 10 is mounted, the rotor comprising a drive pinion
46. A toothed belt 50 has been fitted to the toothed belt disc 36
and the drive pinion 46. On the external circumference of the
toothed belt 50 and between toothed belt disc 36 and drive pinion
46 there is a tensioning pulley 52 which is rotatably mounted on
the side leg of the frame 30. A spring wire 56 fixedly provided on
a pin on the side leg of the frame presses against the support
plate 38 and acts upon the latter with an anti-clockwise torque in
FIG. 4, whereby the support plate 38 is brought into the pivoted
position shown in FIG. 4, in which the tensioning pulley 52 is out
of engagement with the toothed belt 50. The support plate takes up
this pivoted position if the load transmitted by the toothed belt
50 is low. Upon an increased load, there acts onto the support
plate 38 a torque opposite to the spring wire 56 and which is
caused by the tensile stress in the toothed belt 50. This tensile
stress has a component in tangential direction with respect to the
pivotal axis of the support plate 38. The higher the tensile load,
the larger this component. On pivoting of the support plate 38 in
opposition to the action of the spring wire 56, the toothed belt 50
comes into engagement with the periphery of the tensioning pulley
52, so that the toothed belt 50 is tensioned according to the
increase of the transmitted load.
[0046] The stator 58 of the electric motor 10, together with the
complete signaling electronic means, is mounted on a printed
circuit board 60. The printed circuit board 60 also has the Hall
sensors 12, 14 shown in FIG. 1. Further, it has at least one
condenser 62 which has a high capacity and serves as an energy
reserve. The printed circuit board 60 is attached to a side leg of
the frame 30 by stud bolts, for example.
[0047] The functionality of the belt retractor described is
determined by the input signals processed in the microcomputer 16
and by the program routines kept available in its program memory.
Thus, with an identical electromechanical basic design there can be
realized belt retractors having an extremely variable
functionality.
* * * * *