Drive Arrangement

• US 20150088384A1
• Filed: 01/25/2013
• Published: 03/26/2015
• Est. Priority Date: 04/23/2012
• Status: Active Grant

• Current Assignee: Autoliv Development AB (Autoliv Incorporated)
• Original Assignee: Autoliv Development AB (Autoliv Incorporated)
• Inventors: Darraba, Roger
• Granted Patent: US 9,505,378 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 2022/4666 characterised by electric actuators
• CPC Class Codes: B60R 22/46 Reels with means to tension the belt in an emergency by forced winding upelectrical circuits for triggering safety arrangements B60R21/01 ; tensioners using reels only guiding the belt during normal use, e.g. splitted reels B60R22/195
• CPC Class Codes: H02P 29/025 the fault being a power interruption
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
• CPC Class Codes: H02P 4/00 Arrangements specially adapted for regulating or controlling the speed or torque of electric motors that can be connected to two or more different electric power supplies vector control H02P21/00
• CPC Class Codes: H02P 7/04 by means of a H-bridge circuit

Abstract

A drive arrangement (1) comprising an input (2) from a primary power source (5) and an auxiliary power source (7). The drive arrangement (1) incorporates a DC-DC converter (8) and a motor driver circuit (14). The motor driver circuit (14) is connected to a motor (18) in a motorised seat belt retractor. The drive arrangement (1) drives the motor (18) in the event of a crash situation. If the connection between the drive arrangement (1) and the primary power source (5) is lost then the drive arrangement (1) draws power from the auxiliary power source (7) to drive the motor (18). The auxiliary power source (7) can also assist the primary power source (5) by limiting the current drawn from the primary power source (5).

Claims

1. A drive arrangement for driving a motor in a vehicle safety device, the arrangement comprising:

a power supply input configured to be connected to a primary power source,

an auxiliary power source,

a DC-DC converter circuit configured to operate in at least a voltage boost mode, the DC-DC converter circuit having a DC-DC converter circuit input that is connected to the auxiliary power source,

a motor driver circuit having a motor driver circuit input that is connected to an output of the DC-DC converter circuit and to the power supply input, and

a control unit connected to the DC-DC converter circuit, the control unit being configured to activate the DC-DC converter circuit to operate in the voltage boost mode to increase the voltage to the motor driver circuit input if the voltage at the motor driver circuit input is below a predetermined level.

2. A drive arrangement according to claim 1, wherein the auxiliary power source is a supercapacitor.

3. A drive arrangement according to claim 2, wherein the supercapacitor comprises a plurality of supercapacitor cells.

4. A drive arrangement according to claim 3, wherein a shunt regulator is provided across each of the supercapacitor cells to regulate the voltage and current applied to each of the cells.

5. A drive arrangement according to claim 2, wherein the drive arrangement further comprising a voltage and current limiter to limit the voltage and current input to the supercapacitor.

6. A drive arrangement according to claim 2, further comprising wherein the DC-DC converter circuit is a bi-directional converter that is also configured to operate in a buck convertor mode which, when activated provides a reduced voltage to the primary power source to a lower level and inputs the reduced voltage into the supercapacitor.

7. A drive arrangement according to claim 6, wherein the control unit is connected to control switches in the DC-DC converter circuit and the control unit is configured to modulate the control switches in the DC-DC converter circuit so that the DC-DC converter circuit operates in either the buck mode or the boost mode in response to the sensed primary power source voltage and the sensed voltage across the supercapacitor.

8. A drive arrangement according to claim 1, further comprising wherein the control unit is configured to receive a signal from a crash sensor which is indicative of a crash situation or an anticipated crash situation.

9. A drive arrangement according to claim 1, further comprising wherein the drive arrangement is connected to the motor in a motorized seat belt retractor.

10. A drive arrangement according to claim 1, wherein the drive arrangement further comprising a speed sensor to sense the speed of rotation of the motor and output a speed signal to the control unit which is indicative of the speed of rotation of the motor.

11. A drive arrangement according to claim 1, further comprising wherein the motor driver circuit is an H-bridge motor driver circuit.

12. A drive arrangement according to claim 1, further comprising the drive arrangement incorporated into a seat belt retractor.

13. A seat belt retractor according to claim 12, further comprising wherein the seat belt retractor is operable as a load limiter.

14. A drive arrangement according to claim 1 further comprising the auxiliary power source enabling operation of the motor in the event of a failure of the primary power source.

15. A drive arrangement for driving an electric motor in a vehicle seat belt retractor, the arrangement comprising:

a power supply input configured to be connected to a primary power source,

an auxiliary power source enabling operation of the electric motor in the event of a failure of the primary power source,

a DC-DC converter circuit configured to operate in at least a voltage boost mode, the DC-DC converter circuit having a DC-DC converter circuit input that is connected to the auxiliary power source,

a motor driver circuit having a motor driver circuit input that is connected to an output of the DC-DC converter circuit and to the power supply input, and

a control unit connected to the DC-DC converter circuit, the control unit configured to receive a signal from a crash sensor which is indicative of a crash situation or an anticipated crash situation, the control unit further being configured to activate the DC-DC converter circuit to operate in the voltage boost mode to increase the voltage to the motor driver circuit input if the voltage at the motor driver circuit input is below a predetermined level.