JPH081466Y2 - Torque sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sensor for detecting torque transmitted from an input shaft to an output shaft.

(Prior Art) For example, in a power steering device for a vehicle,
When transmitting the rotation of the steering wheel from the input shaft to the steering wheel via the output shaft, the torque sensor detects the magnitude of the torque transmitted from the input shaft to the output shaft, and the steering is performed according to the magnitude of the torque. There are some which are designed to give an operation assisting force.

As such a torque sensor, for example, Japanese Patent Laid-Open No. 1-24
There is one disclosed in Japanese Patent No. 4322.

This is, as shown in FIG. 16, an input shaft 101 and an output shaft 10 connected to the input shaft 101 via a torsion bar 102.
3, a detection coil 104, and a pair of magnetic detection rings 105 and 106 attached to the outer circumferences of the input shaft 101 and the output shaft 103. The detection coil 104 is connected to an oscillator and generates a magnetic flux passing through both detection rings 105 and 106.

Further, a plurality of teeth 107, 108 are formed along the circumferential direction at the opposite ends of the detection rings 105, 106, respectively, and the relative rotation of the detection rings 105, 106 causes one of the teeth 107 and the other of the teeth 107, 108 to rotate.
The area of the facing portion of 108 is supposed to change.

Then, when torque is transmitted from the input shaft 101 to the output shaft 103, the torsion bar 102 is changed according to the magnitude of the torque.
Is twisted, the area of the facing portion of the tooth 107 of the one detection ring 105 and the tooth 108 of the other detection ring 106 changes, and the impedance changes according to this area change, and the detection coil 104
The output voltage induced in the output shaft changes, and the torque transmitted from the input shaft 101 to the output shaft 103 is detected by the output voltage.

Engaging portions 109 and 110 are formed on the inner circumference of the output shaft 103 and the outer circumference of the input shaft 101, respectively.
3 is fitted through the engaging portions 109 and 110, whereby the relative rotation angle of both shafts is regulated within a certain range, and damage to the torsion bar 102 is prevented.

(Problems to be Solved by the Invention) In the conventional torque sensor, the inner circumference engaging portion 109 is used.
To the detection ring 106 of the output shaft 103 in which the
The engaging positions of the engaging portions 109 and 110 were set to overlap with each other in the radial direction.

Therefore, when a large torque is applied from the input shaft 101 to the output shaft 103, the engaging portions 109 and 110 engage with each other to cause the output shaft 1 to move.
The 03 was greatly deformed, and this deformation sometimes plastically deformed the detection ring 106.

Then, before and after the deformation, the area of the facing portion between the tooth 108 of the one detection ring 106 and the tooth 107 of the other detection ring 105 varies, and the center value of the sensor output largely shifts, and the detected torque and actual However, there was a problem that the difference between the transmission torque and the transmission torque exceeds the allowable range.

(Means for Solving the Problem) An object of the present invention is to provide a torque sensor capable of solving the above-mentioned problems of the conventional technology.

The first aspect of the present invention is characterized in that an input shaft, an output shaft connected to the input shaft via a torsion bar, and at least a pair of magnetic detection rings provided on the outer circumferences of the input shaft and the output shaft. , A detection coil that generates a magnetic flux that passes through both detection rings, and the torque transmitted from the input shaft to the output shaft is detected by the output change from the detection coil according to the relative rotation of both detection rings. In the torque sensor in which the relative rotation of both shafts is regulated within a certain range by fitting the output shaft and the output shaft via engaging portions formed on one inner circumference and the other outer circumference, This is in that the engagement positions of both engagement portions are prevented from overlapping in the radial direction with respect to the detection ring of one shaft on which the inner peripheral engagement portion is formed.

The second feature of the present invention is that an input shaft, an output shaft connected to the input shaft via a torsion bar, and at least a pair of magnetic detection rings provided on the outer circumferences of the input shaft and the output shaft. , A detection coil that generates a magnetic flux that passes through both detection rings, and the torque transmitted from the input shaft to the output shaft is detected by the output change from the detection coil according to the relative rotation of both detection rings. In the torque sensor in which the relative rotation of both shafts is regulated within a certain range by fitting the output shaft and the output shaft via engaging portions formed on one inner circumference and the other outer circumference, In order to reduce the deformation of the detection ring due to the deformation of one of the shafts on at least one of the outer circumference of the one shaft where the inner circumference engaging portion is formed and the inner circumference of the detection ring attached to this outer circumference, A notch is formed To the point it is there.

(Operation) According to the configuration of the first aspect of the present invention, even if one of the shafts formed with the inner peripheral engaging portion is deformed due to the engagement of the input shaft and the output shaft through the engaging portions, Since the engagement positions of both engagement parts are axially separated from the detection ring of one shaft,
The deformation of the detection ring due to the deformation of one of the shafts is smaller than that in the prior art in which the detection ring and the engagement position overlap in the radial direction.

According to the configuration of the second aspect of the present invention, the notch formed between the inner and outer circumferences of the one shaft and the detection ring reduces the deformation of the detection ring due to the deformation of the one shaft.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

A torque sensor 1 shown in FIG. 1 is used in a power steering device, and includes an input shaft 3 connected to a steering wheel (not shown) via a transmission shaft 2 and a torsion bar 4 connected to the input shaft 3. The output shaft 5 is provided.

The torsion bar 4 is connected to the transmission shaft 2 and the input shaft 3 via a pin 6, and is also connected to the output shaft 5 via a pin 7.

The input shaft 3 is supported by the housing 9 via bearings 8, and the output shaft 5 is supported by the housing 9 via bearings 10 and 11. The output shaft 5 is interlockingly connected to a steering wheel (not shown), and a gear 12 fitted to the outer periphery of the output shaft 5 and a gear 12a meshing with the gear 12 serve as a steering assisting motor (not shown). They are linked together. The housing 9 is fixed to the vehicle body.

A first detection ring 13 is fitted on the outer circumference of the output shaft 5, and a second detection ring 14 and a third detection ring 15 are fitted on the outer circumference of the input shaft 3.

A plurality of teeth 16 and 17 are formed along the circumferential direction at the opposing ends of the first detection ring 13 and the second detection ring 14, respectively, and the relative rotation of the first and second detection rings 13 and 14 is performed. As a result, the area of the facing portion between the one tooth 16 and the other tooth 17 is changed.

It should be noted that teeth having the same shape as the first detection ring 13 are formed on the side of the third detection ring 15 at the opposing ends of the second detection ring 14 and the third detection ring 15.
No teeth are formed on the side, and the area of the facing portion is constant.

Further, the detection coil 18 is fixed to the housing 9 so as to cover the opposed ends of the first detection ring 13 and the second detection ring 14, and covers the opposed ends of the second detection ring 14 and the third detection ring 15. Thus, the temperature compensation coil 19 is fixed to the housing 9.

The detection coil 18 and the temperature compensation coil 19 are connected to the oscillator 20 as shown in FIG. 14, one end of each is grounded, and the other end is connected to the inverting input terminal and the non-inverting input terminal of the operational amplifier 21. The steering assisting motor is driven according to the output of the operational amplifier 21, and the steering assisting force is applied.

Then, with the magnetic flux generated by the detection coil 18 passing through the first detection ring 13 and the second detection ring 14, the input shaft 3
When the first detection ring 13 and the second detection ring 14 rotate relative to each other due to torque transmission from the output shaft 5 to the output shaft 5, the area of the facing portions of the teeth 16 and the teeth 17 changes according to the relative rotation angle, and the impedance changes. The output voltage induced in the detection coil 18 changes according to the change.

This output voltage is input to the operational amplifier 21 through the inverting input terminal, amplified, and input to the drive circuit of the steering assisting motor.

Further, when the output voltage of the detection coil 18 changes due to a change in impedance due to a temperature change between the first detection ring 13 and the second detection ring 14, the second detection ring 14 and the third detection ring 14
The output voltage of the temperature compensation coil 19 changes due to the impedance change due to the temperature change with the detection ring 15, and the output of the temperature compensation coil 19 is input to the operational amplifier 21 from the non-inverting input terminal, so that the temperature change occurs. This prevents the output voltage from changing due to.

When the output voltage from the detection coil 18 is equal to or lower than a certain value, the transmission torque is small and the steering assisting force is not required, so that the steering assisting motor is not driven and the dead zone is set.

Then, the input shaft 3 and the output shaft 5 are fitted to each other through the engaging portion 22 formed on the inner circumference of the output shaft 5 and the engaging portion 23 formed on the outer circumference of the input shaft 3. The relative rotation angles of both shafts 3 and 5 are regulated within a fixed value.

That is, as shown in FIGS. 3 and 4, the output shaft 5 is formed with a through hole 24 for inserting the torsion bar 4, and the diameter of the through hole 24 gradually decreases as it goes downward. The engaging portion 22 is formed below the large diameter portion 25 at the upper end thereof. The engagement portion 22 has a pair of opposing curved surface portions 26 having an inner peripheral surface having the same curvature as the inner peripheral surface of the large diameter portion 25, a flat surface portion 27 continuous with the curved surface portion 26, and a curved surface continuous with the flat surface portion. It is formed by a pair of opposed curved surface portions 28 having a larger curvature than the portion 26. Further, the curvature of the curved surface portion 28 is made smaller than the curvature of the inner peripheral surface of the small diameter portion 33 below the engaging portion 22, and the curved surface portions 26, 28 are assumed to be on the concentric circle of the output shaft 5. There is.

As shown in FIGS. 5 to 7, the lower end of the input shaft 3 is a small diameter portion 29, and an engaging portion 23 is formed above the small diameter portion 29. The engagement portion 23 is formed of a pair of opposed curved surface portions 30 and a flat surface portion 31 continuous with the curved surface portion 30.

The curvature of the curved surface portion 30 is larger than that of the curved surface portion 26 and smaller than that of the curved surface portion 28. Further, the distance D1 between the flat portions 31 is smaller than the distance D2 between the flat portions 27 facing each other in parallel. Further, the diameter of the small diameter portion 29 is smaller than the diameter of the small diameter portion 33. Further, the curved surface portion 30 is the input shaft 3
It is supposed to be on a concentric circle.

Therefore, when the input shaft 3 and the output shaft 5 are fitted together, the second
As shown in the figure, the flat portion 27 of the engaging portion 22 and the flat portion 31 of the engaging portion 23 are brought into contact with each other, so that the relative rotation angle between the input shaft 3 and the output shaft 5 falls within a certain range.

The first detection ring 13 is fitted to the outer circumference of the output shaft 5 at the position outside the large diameter portion 25 of the output shaft 5.

As a result, with respect to the first detection ring 13, both engaging portions 22,2
The engagement position of 3 is located inward of the output shaft 5 in the axial direction, and does not overlap in the radial direction.

The radial thickness of the output shaft 5 is determined by the first detection ring 13
The engaging positions of the engaging portions 22 and 23 are made larger than the engaging portion of.

According to the configuration of the above-described embodiment, even if the torque is transmitted from the input shaft 3 to the output shaft 5 and the engaging portions 22 and 23 are engaged with each other so that the output shaft 5 is deformed, the first detection ring 13 remains. Since the engagement positions of both engagement portions 22 and 23 do not overlap in the radial direction, the amount of plastic deformation of the first detection ring 13 can be made smaller than that of the conventional one. This makes it possible to reduce fluctuations in the output voltage of the detection coil 18 due to fluctuations in the area of the facing portion of the teeth 16 and 17 before and after deformation, reduce the deviation of the center value of the output voltage, and reduce the detected torque relative to the transmission torque. It is possible to prevent the difference from exceeding the allowable range.

The present invention is not limited to the above-mentioned embodiments, but may be, for example, the following embodiments.

In the following description of the embodiments, the differences from the above embodiments will be described, the same parts will be denoted by the same reference numerals, and description thereof will be omitted.

In the embodiment shown in FIGS. 8 and 9, a plurality of notches 34 are formed on the outer periphery of the output shaft 5 into which the first detection ring 13 is fitted. The notch 34 is formed in both engaging portions 22, 23.
Where the maximum amount of deformation of the output shaft 5 due to the engagement of
That is, it is formed at four radially outward positions of the flat surface portion 27 of the engaging portion 22. The notch 34 reduces the internal stress generated in the first detection ring 13 due to the deformation of the output shaft 5,
The deformation of the detection ring 13 is reduced.

In the embodiment shown in FIGS. 10 and 11, a plurality of notches 35 are formed on the inner circumference of the first detection ring 13 fitted to the output shaft 5. The position and action of the notch 35 are shown in FIGS.
This is similar to the illustrated embodiment.

The embodiment of FIG. 12 is similar to the embodiment of FIGS. 10 and 11 in that a notch 35 is formed in the inner circumference of the first detection ring 13, but the engagement of both engaging portions 22, 23 The position is a position overlapping the detection ring 13 in the radial direction as in the conventional case.

In the embodiment shown in FIGS. 8 to 12, the output shaft 5
Notches may be provided on both the outer circumference of the first detection ring 14 and the inner circumference of the first detection ring 14.

In the embodiment shown in FIG. 13, the axial length of the first detection ring 13 is made long and the axial length of the second detection ring 14 is made short so that the first detection ring 13 and the second detection ring 14 are The opposing end is moved outward in the axial direction of the output shaft 5 as compared with the above embodiment, and the detection coil 18 is also moved in the axial direction in accordance with this movement.

As a result, the positions of the opposing end portions of the first detection ring 13 and the second detection ring 14 that most affect the output fluctuation of the detection coil 18 are separated from the output shaft 5 in the axial direction, and the first position due to the deformation of the output shaft 5 (1) The influence of the deformation of the detection ring 13 can be reduced to reduce the output fluctuation of the detection coil 18.

Further, in the above embodiment, the inner circumference engaging portion is formed on the output shaft 5, but the inner circumference engaging portion may be formed on the input shaft 3 and the outer circumference engaging portion may be formed on the output shaft 5.

 Besides, the respective embodiments can be combined.

FIG. 15 relates to a comparative example, and the difference from the conventional example of FIG.
Similar to the embodiment of FIG. 13, the detection ring 106 and the detection ring 1
The end opposite to 05 is located further apart from the output shaft 103 in the axial direction than that in FIG.

Table 1 below shows the comparison results when the static torsion test was performed on the torque sensors of the examples of the present invention, comparative examples, and conventional examples.

The torque load is 4k by first rotating the input shaft in one direction.
Load gf.m, then rotate in the other direction to load 4kgf.m, then rotate in one direction to load 8kgf.m, then rotate in the other direction to load 8kgf.m Then, similarly, increase the load torque by 4 kgf.m to load up to 16 kgf.m, and then release the load.

Then, the change amount V (%) of the output voltage of the detection coil after the torque is applied and the torque is released before the torque is applied
And the amount of change in impedance | Z | (%) were measured.
The maximum amount of change in A-1-L among the samples was set as 100%, and the amount of change in each sample was shown relatively.

In Table 1, Sample A is a conventional example having a structure shown in FIG. 16, Sample B is a comparative example having a structure shown in FIG. 15, Sample C is an example having the structure shown in FIG. An example of the structure is shown.
Further, R shows the result when the torque load is started by rotating the input shaft to the right, and L shows the result when the torque load is started by rotating the input shaft to the left.

From the above test results, compared with the conventional example A, the present examples B, C, D
In (1), since the variation in impedance that represents the area variation of the opposite ends of the teeth of both detection rings is small, it can be seen that the deformation of the detection ring due to the deformation of the output shaft is small and the output fluctuation from the detection coil can be made small.

In the above-described embodiment, the case where the pair of detection rings is described has been described, but it goes without saying that the present invention can be applied to a torque sensor having a plurality of pairs of detection rings.

(Effect of the Invention) According to the torque sensor of the present invention, even if one shaft having the inner peripheral engaging portion is deformed, the relative rotation of the input shaft and the output shaft is restricted via the respective engaging portions. , The deformation of the detection ring provided on the shaft can be made smaller than before, the relative displacement of the pair of detection rings due to the deformation can be made small, and the deviation of the center value of the sensor output can be prevented from increasing, and the transmission torque and detection can be detected. It is possible to prevent the problem that the torque difference exceeds the allowable range.

[Brief description of drawings]

1 to 14 relate to an embodiment of the present invention. FIG. 1 is a cross-sectional view of a torque sensor, FIG. 2 is a cross-sectional view for explaining the structure of essential parts, FIG. 3 is a plan view of an output shaft, and FIG. 4 is a vertical sectional view of the output shaft, FIG. 5 is a front view of the lower end of the input shaft, FIG. 6 is a bottom view of the input shaft, FIG. 7 is a side view of the input shaft, and FIG. 8 is a different embodiment. FIG. 9 is a plan view of the output shaft and the detection ring according to FIG.
Vertical cross-sectional view with the input shaft fitted to the output shaft in the figure,
FIG. 10 is a plan sectional view of an output shaft and a detection ring according to different embodiments, FIG. 11 is a longitudinal sectional view of the output shaft in FIG. 10 with the input shaft fitted, FIGS. 12 and 13 The drawings are vertical cross-sectional views of the output shaft and the detection ring according to different embodiments, FIG. 14 is an electric circuit diagram, FIG. 15 is a partial vertical cross-sectional view of a torque sensor according to a comparative example, and FIG. 16 is a conventional example. It is a partial longitudinal cross-sectional view of such a torque sensor. 3 ... input shaft, 4 ... torsion bar, 5 ... output shaft,
13 …… First detection ring, 14 …… Second detection ring, 18 ……
Detection coil, 22 ... Inner circumference engaging part, 23 ... Outer circumference engaging part, 3
4,35 …… Notches.

Claims (2)

[Scope of utility model registration request] 1. An input shaft, an output shaft connected to the input shaft via a torsion bar, at least a pair of magnetic detection rings provided on the outer circumferences of the input shaft and the output shaft, and both detection rings. And a detection coil that generates a magnetic flux, and the torque transmitted from the input shaft to the output shaft is detected by the output change from the detection coil according to the relative rotation of both detection rings, and the input shaft and the output shaft are In the torque sensor in which the relative rotation of both shafts is restricted within a certain range by being fitted through the engaging portions formed on one inner circumference and the other outer circumference, the inner circumference engaging portion is A torque sensor characterized in that the engagement position of both engagement portions is prevented from overlapping in the radial direction with respect to the formed detection ring of one shaft. 2. An input shaft, an output shaft connected to the input shaft through a torsion bar, at least a pair of magnetic detection rings provided on the outer circumferences of the input shaft and the output shaft, and both detection rings. And a detection coil that generates a magnetic flux, and the torque transmitted from the input shaft to the output shaft is detected by the output change from the detection coil according to the relative rotation of both detection rings, and the input shaft and the output shaft are In the torque sensor in which the relative rotation of both shafts is restricted within a certain range by being fitted through the engaging portions formed on one inner circumference and the other outer circumference, the inner circumference engaging portion is A notch is formed in at least one of the outer circumference of the formed shaft and the inner circumference of the detection ring attached to the outer circumference so that deformation of the detection ring due to deformation of the one shaft can be reduced. Characterized by Rukusensa.