Actuator with ball screw drive

• US 9,939,054 B2
• Filed: 10/09/2015
• Issued: 04/10/2018
• Est. Priority Date: 10/09/2015
• Status: Active Grant

• Current Assignee: Command Access Technology, Inc.
• Original Assignee: Command Access Technology, Inc.
• Inventors: Stephenson, Jeffrey J.
• Primary Examiner(s): Elahmadi, Zakaria
• Application Number:
  US14/879,937
• Publication Number:
  US 20170102058A1
• Time in Patent Office: 914 Days
• CPC Class Codes: E05B 2047/0023 Nuts or nut-like elements moving along a driven threaded axle
• CPC Class Codes: E05B 2047/0091 Retrofittable electric locks, e.g. an electric module can be attached to an existing manual lock electrically driven keys E05B2047/0083
• CPC Class Codes: E05B 47/0012 with rotary electromotors actuators with rotary electromotors per se H02K7/06, H02K23/68
• CPC Class Codes: E05B 47/023 the bolt moving pivotally or rotatively
• CPC Class Codes: E05B 65/1053 sliding towards and away form the door
• CPC Class Codes: F16H 25/2214 with elements for guiding the circulating balls
• CPC Class Codes: F16H 25/2228 the device for circulation forming a part of the screw member

Abstract

An embodiment is an electromechanical door latch system including a latch device configured for motion between a latched position and an unlatched position. A manually actuated mechanical apparatus is coupled to the latch device and configured to move the latch device to the unlatched position in response to force applied by a user to a component of the mechanical apparatus. An electromechanical actuator system moves the latch device to an actuator unlatched position in response to an electrical signal from an access control device. The electromechanical actuator system includes a control module, a motor, and a ball screw drive including a ball screw or threaded nut, with one coupled to the motor shaft and the other configured for connection to a latch mechanism, and at least one recirculating ball circuit including ball bearings for transferring torque from the motor to the ball screw drive.

Claims

1. An electromechanical door latch system, comprising:

a latch device configured for motion between a latched position and an unlatched position when installed on a door having a first side and a second side, the latched position preventing the door from opening;

a mechanical apparatus coupled to the latch device and configured to move the latch device to the unlatched position in response to force manually applied by a user to a component of the mechanical apparatus, wherein the component of the mechanical apparatus is a push pad mounted to the first side of the door;

an electromechanical actuator system coupled to the latch device to move the latch device to an actuator unlatched position in response to an electrical signal from an access control device, the electromechanical actuator system including a control module, a motor with a motor shaft, and a mechanism to translate the rotational output force of the motor to a force to actuate the latch device;

wherein said mechanism comprises a ball screw drive comprising a ball screw and a threaded nut, and wherein one of the ball screw or threaded nut is configured for coupling to the latch device or mechanical apparatus and constrained from rotation, and the other of the ball screw or threaded nut is coupled to the motor shaft, and at least one recirculating ball circuits including ball bearings for transferring torque from the motor to drive the one of the ball screw and nut along an axis of the ball screw, the mechanism further including a mechanical linkage configured to couple the one of the ball screw or the threaded nut to the latch device.

2. The system of claim 1, wherein an end of the ball screw is attached to the motor shaft, and the threaded nut is constrained from rotation and is coupled to the latch device or the mechanical apparatus.

3. The system of claim 1, wherein the ball screw drive is free of bearings at a ball screw end distant from the motor to support the ball screw.

4. The system of claim 1, wherein the at least one recirculating ball circuits is configured to recirculate the ball bearings through a recirculation path external to the ball screw.

5. The system of claim 1, wherein the recirculation path is defined within the threaded nut.

6. The system of claim 1, wherein the recirculation path is defined within the ball screw.

7. The system of claim 6, wherein the at least one recirculating ball circuit comprises a first recirculating ball circuit and a second recirculating ball circuit, the first and second recirculating ball circuits spaced apart along the ball screw, and wherein the drive system is configured to provide a path of travel shorter than a longitudinal extent of the nut along the ball screw axis.

8. The system of claim 1, further comprising a push pad mechanical linkage configured to couple the push pad to the latch device without exerting turning force on the one of the ball screw or the threaded nut when the push pad is manually activated.

9. A kit for installation in a door latch system including a latch device configured for motion between a latched position and an unlatched position when installed in a door having a first side and a second side, and a mechanical apparatus coupled to the latch device and configured to move the latch device to the unlatched position in response to force manually applied by a user to a push pad component of the mechanical apparatus, the kit comprising:

an electromechanical actuator system configured for coupling to the latch device to move the latch device to an actuator unlatched position in response to an electrical signal from an access control device, the electromechanical actuator system including a control module, a motor with a motor shaft, and a mechanism to translate the rotational output force of the motor to a force to actuate the latch device;

wherein the mechanism comprises a ball screw drive comprising a ball screw and a threaded nut, and wherein one of the ball screw or threaded nut is configured for coupling to the latch device or to the push pad component of the mechanical apparatus and constrained from rotation, and the other of the ball screw or threaded nut is coupled to the motor shaft, and at least one recirculating ball circuits including ball bearings for transferring torque from the motor to drive the one of the ball screw and nut along an axis of the ball screw; and

the mechanism further comprising a mechanical linkage configured to couple the one of the ball screw or the threaded nut to the latch device.

10. The kit of claim 9, wherein an end of the ball screw is attached to the motor shaft, and the threaded nut is constrained from rotation and is coupled to the latch device or the mechanical apparatus.

11. The system of claim 10, wherein the ball screw drive is free of bearings to support the ball screw.

12. The system of claim 10, wherein the at least one recirculating ball circuit is configured to recirculate the ball bearings through a recirculation path external to the ball screw.

13. The system of claim 10, wherein the recirculation path is defined within the threaded nut.

14. The system of claim 9, wherein the recirculation path is defined within the ball screw.

15. The system of claim 10, wherein the at least one recirculating ball circuit comprises a first recirculating ball circuit and a second recirculating ball circuit, the first and second recirculating ball circuits spaced apart along the ball screw.

16. The system of claim 14, wherein the at least one recirculating ball circuit comprises a first recirculating ball circuit and a second recirculating ball circuit, the first and second recirculating ball circuits spaced apart along the ball screw, and wherein the drive system is configured to provide a path of travel shorter than a longitudinal extent of the nut along the ball screw axis.