JPH0723713Y2 - Torque sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a torque sensor used in a power steering device of an industrial machine such as an automobile.

2. Description of the Related Art As a torque sensor of this type, as a torque sensor of this type, two strong shafts that interlock with two shafts connected via a torsion bar and change the magnetic coupling state of the facing end faces by relative rotation of these shafts are used. It is known that a magnetic detection ring is provided and the torque is detected by detecting the magnetic coupling state of these two detection rings.

However, in the conventional torque sensor, in order to change the magnetic coupling state between the two detection rings by the relative rotation of the two detection rings, it is necessary to make the end faces of the detection rings into a tooth shape or a twisted surface, and the shape of the detection rings is complicated. It is difficult to process. In addition, a current is passed through a ring-shaped detection coil arranged around the two detection rings to detect the magnetic coupling state of the two detection rings. Magnetic flux is generated, which causes an eddy current to flow in the detection ring,
This becomes eddy current loss. And due to this eddy current loss,
The overall magnetic flux density is reduced and the sensitivity of the sensor is reduced. If the detection ring is made of a high-permeability alloy such as permalloy or an amorphous alloy, the sensitivity will be improved, but it will be expensive, and a decrease in the sensitivity due to eddy current loss cannot be avoided.

An object of the present invention is to solve the above problems and to provide a torque sensor which has a simple shape, is inexpensive, and has high sensitivity.

Means for Solving the Problems The torque sensor according to the present invention interlocks with each of two shafts connected via a torsion bar, and two detections in which the magnetic coupling state of the opposed end faces changes due to the relative rotation of these shafts. These two with a ring
In a torque sensor for detecting torque by detecting the magnetic coupling state of two detection rings, the two detection rings are made of a non-magnetic material, and a striped high-permeability alloy layer extending in the axial direction is formed on their surfaces. It is formed at intervals in the circumferential direction.

Action A striped high-permeability alloy layer extending in the axial direction is formed on the surface of the non-magnetic detection ring at intervals in the circumferential direction, so the end surface of the detection ring is a flat surface perpendicular to the axial direction. Even so, the relative rotation of the two rings changes their magnetic coupling state. Further, since the high-permeability alloy layers are formed at intervals in the circumferential direction, the circumferential component of the eddy current is blocked.

Embodiments Embodiments in which the present invention is applied to a torque sensor of a power steering device for an automobile will be described below with reference to the drawings.

FIG. 1 shows a torque sensor (3) provided between the input shaft (1) and the output shaft (2).

The input shaft (1) and the output shaft (2) are connected via a torsion bar (4), and their connecting ends are close to each other. Although not shown, the other end of the input shaft (1) is connected to the steering wheel and the other end of the output shaft (2) is connected to the steering gear.

The torque sensor (3) is configured as follows.

A first detection ring (5) is formed on the outer circumference of the connecting end of the output shaft (2).
The second detection ring (6) and the third detection ring (7) are fixed to the outer periphery of the connecting end portion of the input shaft (1) with a slight gap in the axial direction between the first detection ring and the first detection ring. The ring (5) and the second ring (6) face each other with a small gap in the axial direction. A ring-shaped first detection coil (8) is arranged around the first ring (5) and the second ring (6) so as to straddle the first ring (5) and the second ring (6). A second detection coil (9) similar to the above is arranged in the periphery so as to extend over these. The detection coils (8) and (9) are wound around the ring-shaped magnetic cores (10) and (11).

The three rings (5), (6) and (7) have the same structure and the details of the first ring (5) are shown in FIG.

The rings (5), (6) and (7) are made of a non-magnetic material such as aluminum, synthetic resin or SUS304 in a cylindrical shape, and both end surfaces thereof are flat surfaces perpendicular to the axial direction.
High magnetic permeability alloy layers (12), (13) and (14) extending in the axial direction are formed at circumferentially spaced intervals on both end surfaces and outer peripheral surfaces of the rings (5), (6) and (7). The high-permeability alloy layers (12), (13) and (14) are formed, for example, by coating a high-permeability alloy such as permalloy or amorphous alloy in a striped shape by a process such as sputtering or electroless plating.

An electric current is applied to the first coil (8), which detects the magnetic coupling state between the first ring (5) and the second ring (6). Current is also applied to the second coil (9), which causes the second ring (6) and the third ring (7).
The magnetic coupling state of is detected.

When torque acts between the input shaft (1) and the output shaft (2), the torsion bar (4) is twisted and the first ring (5)
Relative rotation occurs between and the second ring (6). When the first ring (5) and the second ring (6) rotate relative to each other, the positions of these high-permeability alloy layers (12) and (13) in the circumferential direction are displaced, so that even if the end faces are flat. , Ring (5)
A change occurs in the magnetic coupling state of (6). Therefore, the torque is detected by detecting the magnetic coupling state with the first coil (8). Further, the magnetic coupling state of the second ring (6) and the third ring (7) is detected by the second coil (9), and the output of the first coil (8) is output based on the output of the second coil (9). By compensating for, temperature compensation is performed.

When current flows through the coils (8) (9), the ring (5)
Axial magnetic flux is generated in (6) and (7), which causes the high-permeability alloy layers (12) and (13) of the rings (5), (6) and (7).
Eddy current flows in (14). However, since the high-permeability alloy layers (12), (13) and (14) are formed at intervals in the circumferential direction, the circumferential component of the eddy current is blocked, and the eddy current and eddy current loss Is reduced and the sensitivity of the sensor is improved.

The volume resistivity at a frequency of 6 KHz was compared between the non-magnetic detection ring having a high-permeability alloy layer formed on the entire surface (comparative example) and the detection ring of the above example. Then, the example was 1.5. This also shows that the eddy current in the example is small.

In the above embodiment, the high magnetic permeability alloy layer extends linearly in parallel with the axial direction of the detection ring, but the high magnetic permeability alloy layer may be twisted with respect to the axial direction of the detection ring.

Effect of the Invention According to the torque sensor of the present invention, as described above, since the high-permeability alloy layer is formed only on the surface of the non-magnetic detection ring, the cost can be reduced as a whole. Also,
A striped high-permeability alloy layer extending in the axial direction is formed on the surface of the non-magnetic detection ring at intervals in the circumferential direction, so the end surface of the detection ring should be a flat surface perpendicular to the axial direction. Even so, the relative rotation of the two rings changes their magnetic coupling state. Therefore, the shape of the detection ring can be simplified, and the processing becomes easy. Furthermore, since the high-permeability alloy layers are formed at intervals in the circumferential direction, the circumferential component of the eddy current is blocked, the eddy current loss is reduced, and the sensitivity of the sensor is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a torque sensor showing an embodiment of the present invention, and FIG. 2 is a perspective view of a detection ring of the torque sensor. (1) ... Input shaft, (2) ... Output shaft, (3) ... Torque sensor, (4) ... Torsion bar, (5) (6) ...
… Detection ring, (12) (13) …… High permeability alloy layer.

Claims (1)

[Scope of utility model registration request] 1. A two detection ring, which is interlocked with each of two shafts connected via a torsion bar, and whose magnetically coupled state of opposite end faces is changed by relative rotation of these shafts. In the torque sensor for detecting the torque by detecting the magnetic coupling state, the two detection rings are made of a non-magnetic material, and a striped high-permeability alloy layer extending in the axial direction is formed on the surface of these two detection rings in the circumferential direction. A torque sensor that is formed at intervals.