Magnetic load sensor for use in a linear motion actuator, and a linear motion actuator

Patent metadata

Field	Value
Publication number	US-9846090-B2
Application number	US-201214235106-A
Country	US
Kind code	B2
Filing date	Jul 24, 2012
Priority date	Jul 28, 2011
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A magnetic load sensor unit ( 1 ) is provided which can detect the magnitude of an axial load applied by a linear motion actuator ( 14 ) to a friction pad ( 22 ). The magnetic load sensor unit ( 1 ) includes a magnetic target ( 4 ) which generates a magnetic field, and a magnetic sensor ( 5 ) designed to move relative to the magnetic target ( 4 ) corresponding to the axial load.

First claim

What is claimed is:

1. A magnetic load sensor unit for use in a linear motion actuator, the magnetic load sensor unit being configured to detect an magnitude of an axial load applied to an object by the linear motion actuator, and comprising:
a flange member annularly shaped so that a rotary shaft can extend through the flange member, and configured to be deflected when the axial load is applied;
a support member annularly shaped so that the rotary shaft can extend through the support member, and supporting a radially inner portion or a radially outer portion of the flange member;
a magnetic target which generates a magnetic field, the magnetic target being fixed to one of the flange member and the support member; and
a magnetic sensor fixed to the other of the flange member and the support member, and configured such that a position of the magnetic sensor relative to the magnetic target changes in an axial direction corresponding to the axial load, the magnetic sensor being configured to detect the axial load based on a relative displacement between the magnetic target and the magnetic sensor in the axial direction, wherein
the magnetic target includes an S-pole and an N-pole that are arranged adjacent to each other in the axial direction.

2. The magnetic load sensor unit of claim 1 , wherein the magnetic target comprises at least two permanent magnets each magnetized in a direction perpendicular to a relative movement direction in which the position of the magnetic sensor relative to the magnetic target changes, wherein the permanent magnets are arranged such that opposite magnetic poles of the permanent magnets are aligned in the relative movement direction, and wherein the magnetic sensor is located in a vicinity of a boundary between the opposite magnetic poles.

3. The magnetic load sensor unit of claim 1 , wherein the flange member and the support member are annular plate members, wherein one of the flange member and the support member includes a tubular portion having a radially outer surface facing a radially inner surface of the other of the flange member and the support member, and wherein the magnetic target and the magnetic sensor are fixed to one and the other of the radially inner surface and the radially outer surface, respectively.

4. The magnetic load sensor unit of claim 1 , wherein positioning means are provided at respective outer peripheral portions of the flange member and the support member, for determining a circumferential relative position between the flange member and the support member.

5. The magnetic load sensor unit of claim 1 , wherein the magnetic sensor comprises an IC element.

6. The magnetic load sensor unit of claim 5 , wherein the IC element comprises a Hall IC.

7. The magnetic load sensor unit of claim 1 , wherein the magnetic sensor comprises a magnetic resistance element.

8. The magnetic load sensor unit of claim 1 , wherein the magnetic sensor comprises a magnetic impedance element.

9. The magnetic load sensor unit of claim 1 , wherein the magnetic target comprises neodymium magnets.

10. A linear motion actuator comprising a rotary shaft to which a rotation of an electric motor is to be transmitted, a linear motion member, a linear motion mechanism for converting a rotation of the rotary shaft to an axial movement of the linear motion member, thereby applying an axial load to an object, and a reaction force receiving member which receives a reaction force that acts on the linear motion mechanism when the axial load is applied to the object, wherein the reaction force receiving member comprises the magnetic load sensor unit of claim 1 .

11. The linear motion actuator of claim 10 , wherein feedback control is performed on the axial load based on an output signal of the magnetic sensor.

12. A linear motion actuator comprising a rotary shaft to which a rotation of an electric motor is to be transmitted, a linear motion member, a linear motion mechanism for converting a rotation of the rotary shaft to an axial movement of the linear motion member, thereby applying an axial load to an object, and the magnetic load sensor unit of claim 1 , wherein the magnetic load sensor unit is mounted between the linear motion member and the object.

13. The linear motion actuator of claim 12 , wherein feedback control is performed on the axial load based on an output signal of the magnetic sensor.

14. The magnetic load sensor unit of claim 1 , wherein the support member supports the flange member, and includes an annular protrusion on a surface of the support member facing the flange member, such that the annular protrusion (i) keeps the flange member spaced apart from a body of the support member, and (ii) allows for a portion of the flange member to be deflected when the axial load is applied.

Assignees

• Takahashi Toru
• Yasui Makoto
• Masuda Yui
• Ntn Toyo Bearing Co Ltd

Inventors

• Takahashi Toru
• Yasui Makoto
• Masuda Yui

Classifications

• F16D2125/10

  Plural pistons interacting by fluid pressure, e.g. hydraulic force amplifiers using different sized pistons · CPC title

• H02K11/20

  for measuring, monitoring, testing, protecting or switching (rectifiers H02K11/04; power electronics H02K11/33) · CPC title

• F16D2066/005

  Force, torque, stress or strain · CPC title

• B60T13/74

  with electrical assistance or drive · CPC title

• F16D2125/48

  with parallel stationary axes, e.g. spur gears · CPC title