JPH0723712Y2 - Torque sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a torque sensor suitable for being applied to, for example, an electric power steering device of an automobile.

[Prior art]

An electric power steering device is being developed as a power steering device for assisting a force for operating a steering wheel of an automobile. This has a structure in which the torque applied to the steered wheels is detected and the electric motor provided in the steering mechanism is rotated according to the detected torque.

By the way, as the torque detecting means, for example, a torque sensor shown in FIG. 4 has been proposed. FIG. 4 is a schematic cross-sectional view showing the structure of the torque sensor. The upper shaft 1a has steering wheels attached thereto and the lower shaft 1c has steering mechanism attached thereto.
Are coaxially connected via a torsion bar 1b, and the upper shaft 1a is rotatably supported via a bearing 3 in a cylindrical case 2 fixed to the vehicle body.

A sleeve 4 made of a non-magnetic material is externally fitted and fixed to the lower end portion (left side in the drawing) of the upper shaft 1a, and the outer circumference of the sleeve 4 is made of a magnetic material
The second cylinders 5 and 6 are externally fitted and fixed to each other with a proper distance in the axial direction. Both axial end surfaces of the first cylinder 5 are flat surfaces perpendicular to the axial center of the upper shaft 1a. The upper end surface of the second cylinder 6 is a plane perpendicular to the axis of the upper shaft 1a, like the first cylinder 5,
A large number of rectangular tooth portions 6a formed at equal pitches in the circumferential direction are provided on the lower end surface. Each tip of the teeth 6a, 6a ... is the upper shaft
It is a plane perpendicular to the axis of 1a.

A third cylinder 7 made of a magnetic material is externally fitted and fixed to the upper end of the lower shaft 1c. The cylinder 7 is attached so that the vertical direction is opposite to the cylinder 6. That is, the tooth portion of the second cylinder 6
6a, 6a ... and the tooth portions 7a, 7a ..

Inside the case 2, magnetic body cylindrical bodies 10A and 10B forming a circumferential groove are fixedly fitted. The cylindrical body 10A is arranged so as to face the facing portions of the first and second cylinders 5 and 6, and the cylindrical body 10B
Are arranged so as to face the facing portions of the second and third cylinders 6 and 7. A first coil 11 and a second coil 12 are wound around the circumferential grooves of these cylindrical bodies 10A and 10B, respectively.

As a result, the cylinder 10A forms a magnetic circuit with the cylinders 5 and 6, and the cylinder 10B forms a magnetic circuit with the cylinders 6 and 7, and the coils 11 and 12 have a terminal voltage corresponding to the magnetic resistance in the magnetic circuit. Occurs.

Then, when the torque is not acting on the torsion bar 1b, the magnetic resistance states of the cylinders 5 and 6 and the cylinders 6 and 7 are calculated so that the terminal voltages of the coils 11 and 12 are equal, and the cylinders
Positioning 5, 6 and 7 respectively. Therefore, by obtaining the difference between the terminal voltages of the coils 11 and 12, the change in coil characteristics due to the change in ambient temperature is offset, and the state of the magnetic resistance corresponding to the relative rotation amount of the cylinders 6 and 7 is detected, and the torsion bar is detected. The torque acting on 1b is detected.

The torque sensor configured as described above is generally shown in FIG.
As shown in FIG. 6, the first, second, and third cylinders 5, 6, 7 and the coils 11, 12 and the cylinders 10A, 10B are transported separately from each other, and At the assembly site where the electric power steering device is assembled, the first, second and third cylinders 5, 6,
The coil 7 is attached to both shafts 1a and 1c by external fitting and fixed, and the coils 11 and 12 are attached to the case 2 by internal fitting and fixing of the cylinders 10A and 10B. That is, the first and second cylinders 5 and 6 are assembled to the upper shaft 1a via the sleeve 4, and the third cylinder 7 is assembled to the lower shaft 1c. Then, in this state, the upper shaft 1a and the lower shaft 1c are coaxially connected to each other via the torsion bar 1b, and the state shown in FIG. 5 is obtained. Further, the coils 11 and 12 respectively wound around the tubular bodies 10A and 10B are assembled in the case 2 to be in the state shown in FIG. And
As described above, the first, second, and third cylinders 5, 6, and 7 are connected to the upper shaft 1a,
Assembled with the lower shaft 1c, with the coils 11, 12 assembled with the case 2, as shown in FIG. 4, the upper shaft with the cylinders 5, 6, 7 assembled on the inner peripheral side of the coils 11, 12. The lower shaft 1c and the lower shaft 1c are inserted and fitted into the electric power steering device.

[Problems to be solved by the device]

However, as described above, each part is separately transported to the assembly site, where each cylinder 5, 6, 7 is transported.
And the coils 11 and 12 and the cylinders 10A and 10B are separately assembled to the upper shaft 1a, the lower shaft 1c and the case 2 and then assembled to the electric power steering device. At the time of assembly at the assembly site, assembling work, foreign matter is mixed in the cylinders 5, 6, 7 etc. in terms of quality,
There was a problem that it was inferior in reliability.

The present invention has been made in view of the above problems,
By assembling each cylinder and each cylinder in which each coil is arranged into one assembly by a resin case provided so as to surround the cylinder, during transportation to the assembly site, assembly at the assembly site, It is an object of the present invention to provide a torque sensor that can prevent foreign matter from being mixed in when assembled and can improve quality.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a first cylinder fixed to one of two shafts connected through a torsion bar, and a third cylinder fixed to the other shaft. The first
Of one or a plurality of second cylinders arranged between one cylinder and a third cylinder and fixed to one of the shafts. A first cylindrical body that is arranged outside and a first coil is arranged inside, and a second coil that is arranged outside the facing portion of the second cylinder and the third cylinder A second tubular body in which the
Is a torque sensor that constitutes a magnetic circuit with the first and second cylinders, and the second cylinder is a magnetic sensor with the second and third cylinders, respectively. It is characterized in that the respective cylinders and the respective cylinders are made into one assembly by a resin case provided so as to surround the above.

[Action]

According to the present invention, as described above, each cylinder and each cylinder in which the coil is arranged are transported to an assembly site in a state of being assembled into one assembly.
On the lower shaft, each cylinder is simultaneously assembled in the case.

〔Example〕

Hereinafter, embodiments of the torque sensor according to the present invention shown in the drawings will be described.

FIG. 1 is a schematic vertical sectional view of a first embodiment of a torque sensor according to the present invention. An upper shaft 1a on which a steering wheel (not shown) is attached and a lower shaft 1c on which a steering mechanism (not shown) is attached
Are coaxially connected via a torsion bar 1b, and the upper shaft 1a is rotatably supported via a bearing 3 in a cylindrical case 2 fixedly attached to a vehicle body (not shown).

And, the first, second, which are attached to the upper shaft 1a and the lower shaft 1c,
The third cylinders 5, 6, 7 and the first coil 11 arranged inside the cylinders 5, 6, 7 facing each other.
The cylindrical body 10A and the second cylindrical body 10B in which the second coil 12 is arranged are made into one assembly by the resin case 30 provided so as to surround the cylindrical bodies 10A and 10B.

The first cylinder 5 and the second cylinder 6 are attached to the upper shaft 1a via the sleeve 4A, and the third cylinder 7 is connected to the lower shaft 1c.
Attached to.

Teeth 6b, 6b ... Are formed on the lower shaft end surface of the second cylinder 6, while tooth portions 7a, 7a are formed on the upper shaft end surface of the third cylinder 7.
Are provided, and the tooth portions 6b, 6b of the second cylinder 6 and the tooth portions 7a, 7a of the third cylinder 7 are opposed to each other with a proper distance. Further, a gap forming body 20 made of a nonmagnetic material is interposed between the first cylinder 5 and the second cylinder 6.

Further, the two coils 11 and 12 are provided in the cylinders 10A and 10B arranged so as to face the facing portions of the first and second cylinders 5 and 6 and the second and third cylinders 6 and 7, respectively. The first cylindrical body 10A and the second cylindrical body 10B form magnetic circuits, respectively, so that the first cylindrical body 10A and the second cylindrical body 10B form the magnetic circuits. ing.

The resin case 30 includes an upper case body 30A and a lower case body 3
It consists of 0B and. The upper case body 30A is the cylindrical body 1
The body 30i is provided so as to surround the outer periphery of 0A and 10B,
At the upper end of the body portion 30i, an upper wall 3 having an opening on the center side is provided.
0a is provided so as to cover the upper side shaft end surface of the first cylinder 5 such that its center side opening edge is smaller than the outer diameter of the first cylinder 5, while the lower end is A lower wall 30b having an opening on the center side is provided, and a projecting portion 30c in the form of a small tube is provided so as to project axially downward from the opening edge on the center side of the lower wall 30b. A locking projection 30d is provided radially outward from the. On the other hand, the lower case body 3
In 0B, the tubular base portion 30e is fixed to the portion of the lower shaft 1c on the side of the third cylinder 7, and the flange portion 30f is provided outward from the upper end of the tubular base portion 30e. A projecting tubular portion 30g is provided so as to project axially upward from the outer peripheral end of the tubular portion 30f.
The protruding portion 30c of the upper case body 30A from the inner surface of the upper end portion of 0g
The locking protrusion 30d facing outward and the locking protrusion 30h locking in the axial direction are provided.

Then, in order to form the cylinders 5, 6, 7 and the cylinders 10A, 10B and the coils 11, 12 into one assembly by the resin case 30, a shape for covering the coils 11, 12 from the inner peripheral side is used. A cylindrical wall 10A, 10B in which each coil 11, 12 is wound in a state of being protected by a protective cover 10a, 10b provided in, a ring-shaped wall body in which the pipe 11a, 12a for coil lead wire is inscribed They are placed one above the other with 13 intervening, and in this state, the outer peripheral portions of these cylinders 10A, 10B are molded with resin using a mold, and the resin case 30
The upper case body 30A is formed in the above shape. Next, the first cylinder 5 and the second cylinder 6 fitted in the sleeve 4A provided with the upward step on the lower side are formed in the inner circumferences of the cylindrical bodies 10A and 10B molded by the upper case body 30A. Insert. on the other hand,
The third cylinder 7 is molded in the lower case body 30B using a mold so that the lower end portion thereof is covered by the lower case body 30B, and the lower case body 30B is pressed from the lower side of the upper case body 30A. , The locking projection 3 of the lower case body 30B
0h is overcome by using the elasticity of the synthetic resin to the locking projection 30d of the upper case body 30A to establish a locked state, and the cylinders 5, 6, 7 and the cylindrical bodies 10A, 10B are made of resin. The case 30 makes one assembly. In the figure, 14 is a pin for positioning the sleeve 4A and the first cylinder 5 in the rotational direction,
It is inserted and fixed in 1a, and is fitted into recessed holes 4a and 5b provided downward in the axial direction from the upper ends of the sleeve 4A and the first cylinder 5 when assembled. Then, the sleeve 4A is fixed in the axial direction by the cutout concave portion of the upper shaft 1a of the sleeve 4A.
It is fixed by stopping the upper end portion 4a protruding upward with respect to 1f by the recessed portion 1f.

Further, a magnetic material pipe material 40 such as an iron pipe is arranged on the outer peripheral surface side of the resin case 30.

In this way, when the pipe material 40 is arranged on the outer peripheral surface side of the resin case 30 surrounding the cylinders 10A and 10B, the magnetic flux due to the external magnetic field is absorbed by the pipe material 40, and the cylinders 5 and 6 and the first cylinder It is possible to reduce the influence of the external magnetic field on the magnetic circuit states of the body 10A, the cylinders 6 and 7 and the second cylindrical body 10B, stabilize the magnetic circuit, and exert the magnetic shield effect. .

Then, the resin case 30 is transported to the assembly site in a state that it is made into one assembly and unitized, and at the assembly site, the first and second cylinders 5 and 6 are connected to the upper shaft 1a.
In addition, the third cylinder 7 is assembled to the lower shaft 1c, and at the same time, the entire third cylinder 7 is incorporated into the case 2. In this way, the resin case
Since the outside is covered with 30, foreign matter does not enter the inside during transportation and during assembly in the electric power steering device at the assembly site.

FIG. 2 shows a torque sensor according to a second embodiment of the present invention. This torque sensor has tooth portions 5a, 6a at the opposite shaft ends of the first cylinder 5 and the second cylinder 6, respectively. Is formed,
A gap forming body 21 made of a non-magnetic material is interposed between the tooth portions 5a and 6a. Then, in the same manner as in the first embodiment, the first cylindrical body 10A and the second coil in which the first, second and third cylinders 5, 6, 7 and the first coil 11 are arranged are provided. A second cylindrical body 10B having 12 arranged therein and a resin case 30 provided so as to surround the cylindrical bodies 10A and 10B are integrated into one unit to form a unit. Note that the details of the configuration are denoted by reference numerals and omitted.

In the second embodiment, the tooth portions 5a, 6a, 6b are formed on the shaft end faces of the first and second cylinders 5, 6 and the second and third cylinders 6, 7 which face each other. , 7a are provided and have the same shape, the magnetic circuit states of the opposing cylinders do not differ due to changes in the ambient temperature, and the torque can always be detected with high accuracy without being affected by the ambient temperature.

FIG. 3 shows a torque sensor according to a third embodiment of the present invention, which has a second cylinder between the first cylinder 5 and the third cylinder 7.
Two cylinders 6A and 6B are provided as the cylinders, and a gap forming body 22 made of a non-magnetic material is interposed between the two cylinders 6A and 6B. Then, in the same manner as in the above-mentioned respective embodiments, the first cylinder 10A having the four cylinders 5, 6A, 6B, 7 and the first coil 11 arranged therein and the second coil 12 having the first coil 11 arranged therein The two cylinders 10B and the resin case 30 provided so as to surround the cylinders 10A and 10B are made into one assembly and unitized. Note that the details of the configuration are denoted by reference numerals and omitted.

According to this third embodiment, the second cylinder is replaced by two cylinders 6
Since it is composed of A and 6B and four cylinders 5, 6A, 6B and 7 are used in total, the cylinders 5, 6A, 6B and 7 can be formed in the same shape and are easy to manufacture, and the cylinders 5 and 6A and Since the magnetic circuits of the cylinders 6B and 7 are independent of each other, and one does not affect the other,
The magnetic circuit state becomes stable.

[Effect of the Invention] According to the present invention, as described above, by forming each cylinder and the cylindrical body in which each coil is arranged inside by the resin case provided so as to surround the cylindrical body, one assembly is obtained. The resin case can prevent foreign matter from being mixed in at the time of assembling, assembling at the assembly site, and at the time of assembling, so that the quality can be improved.

[Brief description of drawings]

1 is a schematic vertical sectional view of a first embodiment of a torque sensor according to the present invention, FIG. 2 is a schematic vertical sectional view of a second embodiment of the present invention, and FIG. 3 is a schematic vertical sectional view of the present invention. 3 is a schematic vertical sectional view of the third embodiment,
FIG. 4 is a schematic vertical sectional view of a conventional torque sensor, FIG. 5 is a schematic sectional view of a ring portion thereof, and FIG. 6 is a schematic sectional view of a coil portion thereof. 1a …… upper shaft, 1b …… torsion bar, 1c …… lower shaft,
5,6,6A, 6B, 7 …… Cylinder, 11,12 …… Coil, 30 …… Resin case

Claims (1)

[Scope of utility model registration request] 1. A first cylinder fixed to one of two shafts connected via a torsion bar, a third cylinder fixed to the other shaft, the first cylinder and the first cylinder. And one or a plurality of second cylinders that are fixed to one of the shafts and that are fixed to one of the three cylinders, and are arranged outside the facing portion of the first cylinder and the second cylinder. And a second coil disposed inside the first cylindrical body having the first coil disposed therein and outside the portion where the second cylinder and the third cylinder face each other. A torque sensor having a second cylinder, wherein the first cylinder forms a magnetic circuit with the first and second cylinders, and the second cylinder forms a magnetic circuit with the second and third cylinders, respectively. The cylinder and the cylinders are formed into one assembly by a resin case provided so as to surround the first and second cylinders. .