JPH0344529A - Torque detector - Google Patents

Abstract

PURPOSE:To obtain high detecting accuracy without using a large magnet by providing a magnetic flux collecting member and concentrating a magnetic flux generated around a shaft by a ring-shaped magnet to the magnetic flux collecting member. CONSTITUTION:Magnetic flux collecting members 11b,11c holding a magnetic flux detecting element 11a therebetween are formed of magnetic material. A magnetic flux generated by a ring-shaped magnet 7 having a relatively large area and spreading in a ring member 8 and a cylindrical body 10 in a peripheral direction is concentrated to the magnetic flux collecting members 11b,11c which are placed at one point in a circumferential direction and have a relatively small area of the passage. As a result, the sensitivity of the magnetic flux detecting element 11a is made good, and the detecting accuracy is improved without using a large magnet. Accordingly, the apparatus can be compact in size.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a torque detector that detects torque generated on a rotating shaft, and in particular, to a non-contact type torque detector using a magnet and a magnetic sensing element. With a simple configuration, fluctuations in detected values due to rotational phase can be prevented, and high measurement accuracy can be obtained with a small magnet.

[Conventional technology]

As a conventional non-contact type torque detector, for example, there is one disclosed in Japanese Unexamined Patent Publication No. 171332/1983.

To briefly explain this conventional torque detector, first and second shafts are connected to be relatively rotatable, and a predetermined pair of magnets having opposite magnetic properties are fixed to the second shaft. A magnetic path member facing the center portions of the pair of magnets is fixed to the shaft, and a magnetic flux detection element for detecting the amount of magnetic flux flowing through the magnetic path member is provided in the housing or the like.

When relative rotation occurs between the first and second axes and the relative position between the magnetic path member and the magnet changes, the amount of magnetic flux flowing through the magnetic path member changes in proportion to the amount of change. Since the direction of the magnetic flux changes depending on the direction of change, it was possible to detect the rotational torque transmitted through the first and second axes.

[Problem to be solved by the invention]

However, since the above-mentioned conventional torque detector has a structure that requires many small magnets, assembly work is troublesome, assembly errors are likely to occur, and the quality of individual magnets is poor. Since it is difficult to completely eliminate variations, the reliability of the device was not very high.

Furthermore, since the predetermined pairs of magnets are scattered in the circumferential direction, the relative position between the magnets and the magnetic flux detection element changes as the rotational position of the shaft changes, which affects the detected value. There is.

Furthermore, of the magnetic flux generated by the magnet, only a small amount of the magnetic flux is sensed by the magnetic flux detection element, so in order to improve detection accuracy it is necessary to use a large magnet, making it difficult to miniaturize the device. Ta.

The present invention has been made by focusing on such unresolved problems of the conventional technology, and has a simple configuration that can prevent fluctuations in detected values due to rotational phase, and without using large magnets. The object of the present invention is to provide a torque detector that can obtain high detection accuracy.

[Means to solve the problem]

In order to achieve the above object, the torque detector of the present invention has the following features:
first and second shafts rotatably supported by a housing; an elastic body connecting the first and second shafts; a ring-shaped magnet fitted around the first shaft; and second
first and second protrusions interposed in a magnetic circuit including the six abrasive stones whose spacing changes in response to relative rotation between the axes of the axes;
A flux member made of an FFI element provided in the housing and interposed in a magnetic circuit including the magnet, and a flux I14 determining means for reducing the flux of the flux passing through the flux collecting unit. And, it was equipped with.

[Effect]

The first and second shafts are rotatable with respect to the housing and are connected via an elastic body, so that when a rotational torque is generated on the first and second shafts, the elastic body Relative rotation occurs between the first and second axes with tearing.

When relative rotation occurs between the first and second axes, the distance between the first and second protrusions changes, so the amount of magnetic flux in the magnetic circuit interposed by the first and second protrusions increases. change,
Along with this, the amount of magnetic flux passing through the magnetic flux collecting member also changes.

Therefore, by measuring the amount of magnetic flux passing through the magnetic flux collecting member using the magnetic flux measuring means, it is possible to detect the relative rotation between the first and second axes, that is, the torque.

In addition, since the magnet is ring-shaped, no matter which position in the circumferential direction the magnetic flux is measured, it will be measured in the same strip. Even if the relative rotational position with respect to the magnetic flux collecting member changes, the detected value is not affected.

Furthermore, since the magnetic flux collecting member is made of a magnetic material,
Since the magnetic flux generated around the shaft by the ring-shaped magnet is concentrated at one location in the circumferential direction, the sensitivity of the magnetic flux measuring means is improved and measurement accuracy is improved.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 to 5 are diagrams showing a first embodiment of the present invention, in which the torque detector according to the present invention is applied to a power steering device for a vehicle.

First, to explain the configuration, in FIG. 1, inside the housing l, there are a human power shaft 2 as a first shaft and an output shaft 3 as a second shaft, which are connected via a torsion bar 4 as an elastic body. is rotatably supported by bearings 5a5b and 5C.

However, input shaft 2. The output shaft 3 and the torsion bar 4 are arranged coaxially, and a bushing 4a is interposed between the input shaft 2 and the torsion bar 4.

A steering wheel is integrally attached to the right end side of the input shaft 2 in FIG. 1 via a steering shaft (not shown) in the rotation direction.

On the other hand, on the left end side of the output shaft 3 in FIG. 1, for example, a pinion shaft (
(not shown) are connected.

Therefore, the steering force generated by the driver steering the steering wheel is applied to the input shaft 2° torsion bar 4. The signal is transmitted to steered wheels (not shown) via the output shaft 3 and the rack and pinion steering device.

A ring-shaped spacer 6 made of a non-magnetic material is fitted onto the manpower shaft 2, and a ring-shaped magnet 7 is fitted onto the spacer 6.

The magnet 7 has poles in the axial direction (horizontal direction in FIG. 1), one pole located on the steering wheel side is in contact with a first ring member 8 made of a magnetic material, and the other pole is in contact with the first ring member 8 made of a magnetic material. is in contact with a second ring member 9 made of a magnetic material, and both ring members 8 and 9 are not in contact with the input shaft 2 by fitting them together with the magnet 7 into the spacer 6. ing.

Therefore, the first ring member 8 and the second ring member 9 are in a non-contact state, and the magnet 7. The first ring member 8 and the second ring member 9 are integral with the input shaft 2 in the rotation direction via the spacer 6.

In addition, on the surface of the second ring member 9 facing left in FIG.
A plurality of protrusions 9a serving as first protrusions are formed at equal intervals in the circumferential direction.

On the other hand, a cylindrical body 10 made of a magnetic material is fitted onto the output shaft 3 via a cylinder 3a made of a non-magnetic material, and a cylinder 10 is fitted on the surface of the cylindrical body 0 facing right in FIG. A plurality of protrusions 10a as the second protrusions are located on the outer orbit of the protrusion 9a and are formed to face the protrusion 9a in a relationship that will be described later.

As shown in FIG. 2, which is a cross-sectional view taken along the line AA in FIG. This prevents relative rotation between the two shafts beyond a predetermined range (approximately ±5 degrees).

Returning to FIG. 1, a protruding portion 8a is formed on the outer circumferential portion of the first ring member 8. The protruding portion 8a protrudes radially from the outer circumferential surface of the magnet 7 and continues throughout the entire circumferential direction.

Furthermore, a protrusion 10b is formed on the outer peripheral portion of the cylinder 10, similarly to the protrusion 8a, and protrudes in the radial direction and continues throughout the entire circumferential direction.

A sensor section 11 is fixed to the outer periphery of the housing 1, and the sensor section 11 includes a magnetic flux detecting element 11a such as a Hall element constituting a magnetic flux measuring means, and an outer periphery of the protruding section 8a on one end side. A magnetic flux collecting member 11b made of a magnetic material, which is close to the surface and whose other end is in close contact with one surface of the magnetic flux detection element 11a, and whose one end is close to the outer peripheral surface of the protrusion 10b and whose other end is the magnetic flux detection element 11a. It has at least a magnetic flux concentrating member 11c made of a magnetic material and close to the other surface of the magnetic flux concentrating member 11c.

Figure 3 is an enlarged view of the main part of Figure 1, and Figures 4 (a) to (
C) is a sectional view taken along the line B-B in FIG. 3.

That is, most of the magnetic flux created by the magnet 7 is
As shown by C1 in the figure, the first ring member 8. allows magnetic flux to pass through it more easily than air, non-magnetic material, etc. Magnetic flux collecting member 11b, magnetic flux detecting element 11a, magnetic flux collecting member 11c, cylinder 10 and second
A magnetic circuit is formed through the ring member 9.

The circumferential protrusions 9a and 10a are arranged as shown in FIG. 4(a) when there is no relative rotation between the human power shaft 2 and the output shaft 3.
As shown in , the distance between the protrusions 9a and 10a is medium, and when a relative rotation (i.e., leftward steering torque) of the human power shaft 2 in the counterclockwise direction with respect to the output shaft 3 occurs, the distance between the projections 9a and 10a is medium. 4
As shown in Figure (b), the distance between the protrusions 9a and 10a becomes smaller, and the rotation of the input shaft 2 in the clockwise direction relative to the output shaft 3 (i.e., the steering torque in the right direction) is reduced. As shown in FIG. 4(C), the protrusions 9a and loa
The distance between them increases.

However, the point in time when the relative rotation of the input shaft 2 in the counterclockwise direction relative to the output shaft 3 reaches its maximum, and the point in time in which the relative rotation in the clockwise direction of the input shaft 2 relative to the output shaft 3 reaches its maximum. The range of relative rotation between the human power shaft 2 and the output shaft 3, the number of protrusions 9a and 10a, etc. are selected so that the distance between the protrusions 9a and 10a varies linearly.

Then, leftward steering torque is generated and the protrusions 9a and 1
When the distance between 0a becomes smaller, these protrusions 9a and 10
The amount of magnetic flux in the magnetic circuit C1 passing between the protrusions 9a and IOa increases, and when a rightward steering torque is generated and the distance between the protrusion 9a and IOa increases, the amount of magnetic flux in the magnetic circuit CI decreases. Note that the change in magnetic flux in the magnetic circuit C1 is absorbed by the change in magnetic flux in other magnetic circuits (for example, the magnetic circuit passing through the spacer 6).

Therefore, the magnetic flux detection element 11 interposed in the magnetic circuit CI
The output of a changes as shown in FIG. 5 in accordance with the direction and magnitude of the steering torque generated in the steering system.

Therefore, since the steering torque of the steering system is detected based on the output of the magnetic flux detection element 11a, the sensor section 11 supplies the steering torque to a controller (not shown), and
The controller appropriately controls, for example, an electric motor connected to a pinion shaft of a rack and pinion type steering device to generate a steering assist torque in the steering system.

Next, the operation of the above embodiment will be explained.

Now, assuming that the vehicle is traveling straight and there is no relative rotation between the input shaft 2 and the output shaft 3, the protrusion 9a and the I
Since Oa maintains the state shown in FIG. 4(a), no change occurs in the magnetic flux created by the magnet 7.

Therefore, the controller to which the output of the sensor section 11 is supplied determines that no steering torque is being generated in the steering system, so no steering assist torque is generated and the steering system maintains the straight traveling state.

When a rotational force is generated on the input shaft 2 by steering the steering wheel, the rotational force is transmitted to the output shaft 3 via the torsion bar 4.

At this time, a resistance force is generated on the output shaft 3 according to the friction force of the steered wheels and the road surface r1u, the N friction of the rank and pinion type steering device configured on the left end side (not shown) of the output shaft 3, etc. A relative rotation occurs between the input shaft 2 and the output shaft 3 in which the output shaft 3 is delayed due to the torsion bar 4 being torn.

Then, if the steering torque is in the left direction, the projection 9a and the IO
The distance between the protrusions 9a and IOa becomes smaller, and if the steering torque is in the right direction, the distance between the protrusions 9a and IOa becomes larger, and the amount of magnetic flux forming the magnetic circuit CI fluctuates.

In the magnetic circuit C1, since the magnetic flux detection element 14a is present between the magnetic flux collecting members 1', 1b and ll'c, fluctuations in magnetic flux will definitely appear in the output of the magnetic flux detection element 11a. However, since there is a relationship as shown in FIG. 5 between the output of the magnetic flux detection element 11a and the steering torque, the steering torque generated in the steering system is detected.

Therefore, when the controller operates, for example, an electric motor connected to the pinion shaft in accordance with the output of the sensor unit 11, a steering assist torque is generated in the steering system, which reduces the steering torque and reduces the burden on the operator. be done.

Furthermore, in the above embodiment, since the magnet 7 is ring-shaped and the first and second ring members 8 and 9 in contact with it are also similar, the magnetic flux density between the protrusions 8a and 10b is , is uniform over the entire circumferential area, so even if the input shaft 2 and output shaft 3 rotate with respect to the housing l, the output of the magnetic flux detection element 11a is not affected, and reliability and accuracy are improved. High detection values can be obtained.

Furthermore, with the configuration of the above embodiment, only one magnet 7 is required, which simplifies the assembly work, and the other structures of the detached village are also simple, so there is an advantage that costs can be reduced.

Moreover, the magnetic flux collecting member l sandwiching the magnetic flux detection element 11a
Since lb and llc are made of a magnetic material, the magnetic flux generated by the ring-shaped magnet 7 having a relatively large area and spreading in the circumferential direction in the first ring member 8 and the cylindrical body lO is transferred to the circumferential direction. Since the magnetic flux can be concentrated on the magnetic flux collecting members 11b and llc which are arranged at one place in the direction and have a relatively small passage area, the sensitivity of the magnetic flux detection element 11a is improved, and there is no need to use a large (strong) magnet. It can also improve the measurement accuracy. Therefore, it is effective for downsizing the device.

If there were no magnetic flux collecting member 11b and Ilc, the magnetic flux passing between the first ring member 8 and the cylinder body 10 would spread in the circumferential direction, so the proportion of magnetic flux passing through the magnetic flux detecting element 11a would decrease. Li, the sensitivity of the magnetic flux detection element 11a is significantly reduced.

FIG. 6 is a diagram showing a second embodiment of the present invention;
It shows the same parts as FIG. 3 described in the embodiment.

That is, in this embodiment, on the outer peripheral surface of the second ring member 9,
This embodiment is the same as the first embodiment, except that a protrusion 9b is formed that protrudes in the radial direction from the outer circumferential surface of the magnet 7 and is continuous over the entire circumferential area.

With such a configuration, the protrusion 8 always maintains a constant distance.
Since a magnetic circuit as shown by C2 in FIG. 6 is formed between the protrusion 9a and the protrusion 9b, the increase/decrease in the magnetic flux in the magnetic circuit C8 due to the change in the distance between the protrusion 9a and lOa is expressed as: Magnetic circuit C! It can be actively absorbed by decreasing or increasing the magnetic flux inside.

Therefore, as the distance between the protrusion 9a and lOa changes,
The magnetic flux in the magnetic circuit C9 changes significantly, and the sensitivity of the magnetic flux detection element 11a can be further improved.

FIG. 7 is a diagram showing a third embodiment of the present invention;
It shows the same parts as FIG. 3 described in the embodiment.

In this embodiment, the magnet 7 has a pole in the radial direction and is directly fitted onto the manpower shaft 2 .

The first ring member 8 is in contact with one pole of the magnet 7 while being fitted onto the outer circumferential surface of the magnet 7, and has a protruding portion 8a that protrudes in the radial direction and continues throughout the entire circumferential direction, and a seventh ring member 8. A protruding portion 8b is formed that protrudes from the surface facing left in the figure and is continuous throughout the entire circumferential direction.

Further, the second ring member 9 is directly fitted onto the human power shaft 2 so as to be in contact with the other pole of the magnet 7, and the second ring member 9 is in contact with the other pole of the magnet 7.
A protrusion 9a is formed to face the surface facing inward in the radial direction of a, and the relationship between the protrusion 9a and lOa is the same as in the first embodiment.

Even with such a configuration, since the magnetic circuits C1 and C2 are formed, the same effect as in the second embodiment can be obtained, and the spacer fitted externally to the input shaft 2 is not required. Therefore, the assembly work becomes easier and the structure becomes cheaper.

In this embodiment, when the outer circumferential surface of the magnet 7 and the one end side of the magnetic flux collecting member 11b are arranged close to each other,
It is also possible to omit the first ring-shaped member 8.

FIG. 8 is a diagram showing a fourth embodiment of the present invention, and a third embodiment of the present invention.
The same parts as in the figure are shown.

That is, in this embodiment, the first ring member 8 is brought into contact with the input shaft 2, the cylinder 10 is directly fitted onto the output shaft 3, and the protrusion 10a is positioned between the input shaft 2 and the protrusion 9a. Furthermore, a projecting portion 9b that is continuous over the entire circumferential area is formed on the outer peripheral surface of the second ring member 9, so that one of the magnetic flux collecting members 1
The end portion of 1c is placed close to the protruding portion 9b.

Note that the magnet 7 has a pole in the axial direction, and is fitted onto the manpower shaft 2 via the spacer 6 .

With such a configuration, one magnetic circuit C□
Ring member 8. Input shaft 2. Protrusion 10a.

9a and the second ring member 9 to form a closed circuit, and the other magnetic circuit C4 is connected to the first ring member 8° and the magnetic flux collecting member 1.
1b, the magnetic flux detection element 11a, the magnetic flux concentrating unit oil, and the second ring member 9 to form a closed circuit.

The amount of magnetic flux configuring one magnetic circuit C,+ is
Although it is determined depending on the distance between the protrusion 9a and lOa, the magnet 7
Since the amount of magnetic flux created by is constant, the human power axis 2
A relative rotation occurs between the output shaft 3 and the protrusions 9a and lOa.
When the distance between them changes and the amount of magnetic flux that makes up the magnetic circuit C1 increases or decreases, the amount of magnetic flux that makes up the magnetic circuit C4 decreases or increases accordingly.

Therefore, by measuring the amount of magnetic flux in the magnetic circuit C4 with the magnetic flux detection element 11a, the distance between the protrusion 9a and lOa, that is, the direction and magnitude of the torque generated between the human power shaft 2 and the output shaft 3 can be detected. can do.

Therefore, even in this embodiment, the same effects as in the first and second embodiments can be obtained, and since the spacer 3a that was externally fitted on the output shaft 3 is no longer required, the assembly work can be reduced accordingly. This makes it easier to operate and has an inexpensive configuration.

FIG. 9 is a diagram showing a fifth embodiment of the present invention, and a third embodiment of the present invention.
The same parts as in the figure are shown.

That is, in this embodiment, both ends are the protruding part 8a and the protruding part 9b.
One magnetic flux collecting member lid made of a magnetic material and close to ji is buried in the sensor section 11, and the magnetic flux member li
The structure is the same as that of the fourth embodiment, except that the magnetic flux detection elements 11a are fixed to each of both ends of d.

Even with such a configuration, the same effects as in the fourth embodiment can be obtained.

FIG. 1θ is a diagram showing a sixth embodiment of the present invention, and shows the same parts as FIG. 3.

That is, in this embodiment, the magnet 7 has a pole in the radial direction and is directly fitted onto the input shaft 2.

The first ring member 8 is fitted onto the input shaft 2 while being in contact with the pole located on the inside in the radial direction of the magnet 7, and the protruding portion 8a is connected to the end of one magnetic flux collecting member 11b. close to the department.

Further, the second ring member 9 is fitted onto the outer peripheral surface of the magnet 7 and is in contact with a pole located on the outside in the radial direction of the magnet 7, and its protruding portion 9b is connected to the end of the other S magnetic flux member 11c. close to the department.

The effects of this embodiment are the same as those of the fourth embodiment, but since the spacer 6 that was fitted onto the input shaft 2 is no longer required, the assembly work is easier than that of the fourth embodiment. At the same time, the configuration is inexpensive.

Note that the protrusions 9a and 10a are not limited to the shapes shown in the above embodiments, and may be, for example, axial protrusions formed by cutting the inner or outer surface of a cylindrical member. It is also possible to take other shapes.

Further, in each of the above embodiments, the torque detector according to the present invention is applied to a power steering device of a vehicle, but the present invention is not limited to this and can be applied to other devices. There may be.

Furthermore, in each of the above embodiments, the input shaft 2 is the first shaft,
Although the output shaft 3 is used as the second shaft, these relationships can also be reversed.

〔Effect of the invention〕

As explained above, according to the torque detector of the present invention,
Because a ring-shaped magnet is used, the amount of magnetic flux at any position in the circumferential direction is measured under the same conditions, which prevents fluctuations in detected values due to rotational phase and has a simple configuration. Therefore, there will be no increase in costs,
Furthermore, since the flux member (11) is provided, the magnetic flux generated around the axis by the ring-shaped magnet can be concentrated in one place in the circumferential direction, which improves the sensitivity of the magnetic flux measuring element and increases the ) It has various effects such as being able to improve measurement accuracy without using a magnet and being effective in downsizing the device.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the configuration of the first embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is an enlarged view of the main part of FIG. 1, and FIG. (a) to (C) are cross-sectional views taken along the line B-B in Fig. 3, where (a) is a state with zero torque, (b) is a state where leftward torque is generated, and (b) is a state where torque is generated in the left direction. C) shows a state where rightward torque is generated, FIG. 5 is a graph showing the relationship between the output torque of the magnetic flux detection element, and FIG. 6 is a cross-sectional view showing the second example of the real can of the present invention. , FIG. 7 is a sectional view showing a third embodiment of the invention, FIG. 8 is a sectional view showing a fourth embodiment of the invention, FIG. 9 is a sectional view showing a fifth embodiment of the invention, and FIG. FIG. 10 is a sectional view showing a sixth embodiment of the present invention. 1...Housing, 2...Input shaft (first shaft), 3
...Output shaft (second shaft), 4...Torsion bar (
elastic body), 7... magnet, 9a... protrusion, 10a...
・Protrusion, 11a... magnetic flux detection element (magnetic flux measuring means),
l l b. 11c, lid... magnetic flux collecting member, C, -C,... magnetic circuit.

Claims (1)

[Claims] (1) First and second rotatably supported by the housing
an elastic body connecting the first and second axes;
a ring-shaped magnet externally fitted on the first shaft; and first and second magnets whose spacing changes depending on relative rotation between the first and second shafts and which are interposed in a magnetic circuit including the magnet. a magnetic flux collecting member made of a magnetic material provided on the housing and interposed in a magnetic circuit including the magnet, and a magnetic flux measuring means for measuring the amount of magnetic flux passing through the magnetic flux collecting member;
A torque detector characterized by comprising: