Electric screw actuator system

• US 7,052,427 B2
• Filed: 04/11/2001
• Issued: 05/30/2006
• Est. Priority Date: 04/11/2000
• Status: Expired due to Fees

• Current Assignee: SKF Engineering & Research Centre BV
• Original Assignee: SKF Engineering & Research Centre BV
• Inventors: Kapaan, Hendrikus Jan, Nervo, Aurelio, Holweg, Eduardus Gerardus Maria
• Primary Examiner(s): Ho, Ha
• Application Number:
  US10/257,152
• Publication Number:
  US 20030139243A1
• Time in Patent Office: 1,875 Days
• Field of Search: 475/1, 475/3, 475/4, 188/71.9, 188/156, 188/158, 188/162
• US Class Current: 475/4
• CPC Class Codes: B62D 1/163 Part of the steering column replaced by flexible means, e.g. cable or belt
• CPC Class Codes: B62D 5/003 Backup systems, e.g. for manual steering B62D5/30 takes precedence
• CPC Class Codes: B62D 5/0448 Ball nuts
• CPC Class Codes: F16H 25/20 Screw mechanisms with automatic reversal F16H25/12

Abstract

An electric screw actuator system, e.g. for an electrically driven and controlled steering device, comprises a screw actuator, an electric motor (2) engaging the screw actuator through a reduction gear mechanism (3), electronic operating means for operating the screw actuator electrically, and a mechanical back-up system for operating the screw actuator in the absence of electric power e.g. in the case of an electric power failure of in the case the electric power is switched off, maintenance, garage parking etc. The mechanical back-up system comprises a manually controllable operation member (4) and an electromagnetic coupling (6), said coupling disengaging the rotation member from the screw actuator in the case of nominal operation and availability of electric power, and engaging the rotation member with the screw actuator in the case of electric power failure.

Claims

1. Electric screw actuator system usable in at least an electrically driven and controlled steering device, the system comprising:

a screw actuator containing at least a nut and a screw;

an electric motor engaging the screw actuator through a reduction gear mechanism;

an electronic operating device for operating the screw actuator electrically; and

a mechanical back-up system for operating the screw actuator in the absence of electric power due to at least one of an electric power failure and the electric power being intentionally switched off, the mechanical back-up system further comprises a manually controllable rotation member and an electromagnetic coupling, the coupling disengaging the rotation member from the screw actuator in the case of normal operation and availability of electric power, and engaging the rotation member with the screw actuator in the case of absence of electric power,

wherein the coupling is connected to an auxiliary gear mechanism which engages the screw actuator in case of absence of electric power, the coupling is connected to an auxiliary drive gear wheel which engages the screw actuator, and the reduction gear mechanism and the auxiliary gear mechanism are integrated, and the reduction gear mechanism comprises a sun gear wheel which is driveable by the electric motor, a fixed ring gear wheel connected to one of the nut and the screw, satellite gear wheels which engage the sun gear wheel and the ring gear wheel and a carrier onto which the satellite gear wheels are rotatably mounted, the carrier engaging the other of the nut and the screw, and the auxiliary drive gear wheel engages an auxiliary carrier onto which auxiliary satellite gear wheels are rotatably mounted, said auxiliary satellite gear wheels engaging an auxiliary ring gear wheel which is fixed with respect to the fixed ring gear wheel, and an auxiliary sun gear wheel connected to the carrier.

2. Electric screw actuator system usable in at least an electrically driven and controlled steering device, the system comprising:

a screw actuator containing at least a nut and a screw;

an electric motor engaging the screw actuator through a reduction gear mechanism;

an electronic operating device for operating the screw actuator electrically; and

a mechanical back-up system for operating the screw actuator in the absence of electric power due to at least one of an electric power failure and the electric power being intentionally switched off, the mechanical back-up system further comprises a manually controllable rotation member and an electromagnetic coupling, the coupling disengaging the rotation member from the screw actuator in the case of normal operation and availability of electric power, and engaging the rotation member with the screw actuator in the case of absence of electric power,

wherein the coupling is connected to an auxiliary gear mechanism which engages the screw actuator in case of absence of electric power, and the reduction gear mechanism and the auxiliary gear mechanism are integrated, and the reduction gear mechanism comprises a sun gear wheel which is driveable by the electric motor, a fixed ring gear wheel connected to one of the nut and the screw, satellite gear wheels which engage the sun gear wheel and the ring gear wheel and a carrier onto which the satellite gear wheels are rotatably mounted, the carrier engaging the other of the nut and the screw, the nut is connected to a housing, the housing furthermore carrying the fixed ring gear wheel which is concentric with respect to the nut and the screw and the coupling, and the screw engages the carrier through a spline/ball mechanism.

3. Electric screw actuator system usable in at least an electrically driven and controlled steering device, the system comprising:

a screw actuator containing at least a nut and a screw;

an electric motor engaging the screw actuator through a reduction gear mechanism;

an electronic operating device for operating the screw actuator electrically; and

a mechanical back-up system for operating the screw actuator in the absence of electric power due to at least one of an electric power failure and the electric power being intentionally switched off, the mechanical back-up system further comprises a manually controllable rotation member and an electromagnetic coupling, the coupling disengaging the rotation member from the screw actuator in the case of normal operation and availability of electric power, and engaging the rotation member with the screw actuator in the case of absence of electric power,

wherein the coupling is connected to an auxiliary gear mechanism which engages the screw actuator in case of absence of electric power, and the reduction gear mechanism and the auxiliary gear mechanism are integrated, and the reduction gear mechanism comprises a sun gear wheel which is driveable by the electric motor, a fixed ring gear wheel connected to one of the nut and the screw, satellite gear wheels which engage the sun gear wheel and the ring gear wheel and a carrier onto which the satellite gear wheels are rotatably mounted, the carrier engaging the other of the nut and the screw, the nut is connected to a housing, the housing furthermore carrying the fixed ring gear wheel which is concentric with respect to the nut and the screw and the coupling, and the axis of the coupling is transverse with respect to the axis of the screw actuator and the coupling engages the auxiliary gear mechanism through bevel gears.

4. Electric screw actuator system usable in at least an electrically driven and controlled steering device, the system comprising:

a screw actuator containing at least a nut and a screw;

an electric motor engaging the screw actuator through a reduction gear mechanism;

an electronic operating device for operating the screw actuator electrically; and

a mechanical back-up system for operating the screw actuator in the absence of electric power due to at least one of an electric power failure and the electric power being intentionally switched off, the mechanical back-up system further comprises a manually controllable rotation member and an electromagnetic coupling, the coupling disengaging the rotation member from the screw actuator in the case of normal operation and availability of electric power, and engaging the rotation member with the screw actuator in the case of absence of electric power,

wherein the mechanical back-up system further comprises a flexible cable drive, capable of transmitting a torque, or a pulling cable or a mechanical linkage, which at one end is connected to the coupling, and which at the other end is provided with a manually operated lever device, the manually operated lever device has a swivel point which is fixed with respect to the screw actuator, the flexible cable drive is connected to the lever device at the swivel point, and an electromagnetic immobilisation device is provided for resisting rotation of the lever device in the case of normal operation and availability of electric power, and for allowing rotation of the lever device in the case of electric power failure.

5. System according to claim 4, wherein the lever device carries the electronic operating means for operating the screw actuator electrically.

6. System according to claim 5, wherein the electronic operating means comprises a joystick.

7. System according to claim 6, wherein the joystick is at a distance from the swivel point.

8. System according to claim 6, wherein the joystick is directly mounted to the swivel point, and is at least one of rotatable and liftable and otherwise movable in at least one of an x, y, and z axis.