JP2765340B2 - Shaft to be measured, torque detector, and method for manufacturing shaft to be measured - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measured shaft for a torque detecting device used for detecting a torque applied to a measured shaft, a torque detecting device, and a method of manufacturing the measured shaft for the torque detecting device. Things.

[0002]

2. Description of the Related Art As a conventional torque detecting device of this type, for example, there is one disclosed in Japanese Patent Application Laid-Open No. Sho 62-185136. Since the output of the torque-output characteristic is saturated, there is a problem that the practicality is poor.

[0003] On the other hand, we have disclosed in Japanese Patent Application No. Hei 3-990.
The present invention has provided a torque detection device capable of stably detecting torque from a low torque region to a high torque region in the specification and drawings of Patent No. 00 (not disclosed at the time of filing this application) .

[0004] That is, as shown in FIG. 10, the torque detector 101, also has a high yield point by heat treatment
The shaft to be measured 1 was formed by melting and joining a high magnetostrictive material 102b to the surface of the base material 102a.
02, at least a portion of the high magnetostrictive material 102b of the shaft to be measured 102 is formed with a plurality of concave portions 103a, 103b at a predetermined angle with respect to the axial direction of the shaft to be measured 102 in the circumferential direction. These concave portions 103
a, 103b, a plurality of convex portions 104a,
By forming the shape magnetic anisotropic portion 104b, the measured shaft 102 is opposed to the shape magnetic anisotropic portion.
The coils 105a and 105b are arranged on the outer peripheral side of the coil 105 via a gap 106, and a yoke 107 made of a material having a high magnetic permeability is provided outside the coils 105a and 105b.

In the torque detecting device 101 having such a structure, the coils 105a and 105b are combined with resistors 111 and 112 to form a bridge circuit as shown in FIG. An excitation oscillator 113 is connected between C and a differential amplifier 114 is connected between the connection points B and B ′. When a torque T is applied to the shaft 102 to be measured, as shown in FIG. The detection output of the torque-output characteristic can be taken out.

According to the present invention, the saturation output torque of the torque-output characteristic is greatly improved.

[0007]

However, such a conventional torque detecting device 101 does not necessarily exhibit a high yield point characteristic depending on the base material of the shaft 102 to be measured, and exhibits a torque-output characteristic. Some appeared to saturate the output at relatively low torque.

[0008] Investigations have shown that it is easy to appear when the base material is made of a material having a high yield point due to surface hardening treatment such as carburizing or nitriding. That is, a high magnetostrictive material is melted in these base materials.
Since it appeared when carburizing or nitriding was performed after joining, it was attempted to first perform surface hardening treatment such as carburizing or nitriding on the base material, and then melt and join the high magnetostrictive material thereon.

[0009] However, easily enters cracks in the measurement axis when the melt-bonding, also, there is a problem that the surface hardened layer by heat at the time of melting and bonding is annealed may fall hardness Was.

[0010] Therefore, a material which is strengthened by carburizing or nitriding cannot be used, and a usable base material is limited, and it is difficult to widely spread the torque detecting device. there were.

Therefore, solving such problems has been a problem.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and expands the range of usable base materials to reliably provide a high yield point to the base material of the shaft to be measured.
An object of the present invention is to provide a torque detecting device capable of stably detecting torque from a low torque region to a high torque region, and to provide a method of manufacturing a shaft to be measured suitable for such a torque detecting device. .

[0013]

According to the present invention, a shaft to be measured for a torque detector according to the present invention is formed by melting a high magnetostrictive material on the surface of a steel shaft base having a high yield point by a surface hardening treatment.
A concave portion and / or a convex portion forming a predetermined angle with respect to the axial direction of the steel shaft at least in a portion of the high shaft magnetostrictive material of the steel shaft; The bottom portion is characterized in that the base material portion is exposed, and the base is subjected to a surface hardening treatment through a portion exposed at the bottom of the concave portion,
The embodiment is characterized in that the surface of the base material portion exposed at the bottom of the concave portion has a Vickers hardness of Hv600 or more.

[0014] The torque detecting device according to the present invention comprises:
A torque measuring device comprising: a shaft to be measured; an exciting unit that forms a magnetic circuit having the shaft to be measured as a part of a magnetic path; and a detecting unit that detects a magnetostrictive component of the shaft to be measured.
The shaft to be measured is made of a material having a high yield point due to a surface hardening treatment, and a high magnetostrictive material is melted on its surface.
At least a high-magnetostriction material portion of the shaft to be measured is formed with a concave portion and / or a convex portion at a predetermined angle with respect to the axial direction of the shaft to be measured. The bottom portion is characterized in that the base material is exposed, and the measured shaft is subjected to a surface hardening treatment on the base material through a portion exposed at the bottom of the concave portion, In an embodiment, the Vickers hardness of the surface of the exposed portion at the bottom of the concave portion is Hv60.
It is characterized by having a configuration of 0 or more, and in the same embodiment, the portion exposed at the bottom of the concave portion has a configuration in which the effective hardened layer depth of Vickers hardness Hv550 or more is 0.2 mm or more. In another embodiment, the surface hardening treatment comprises carburizing,
It is characterized by a chemical heat treatment such as carbonitriding and nitriding, and at least one selected from physical machining such as shot peening, cold rolling and cold forging. With the configuration of the invention relating to the above-described torque detecting device, the above-mentioned conventional problem is solved.

Further, a method of manufacturing a shaft to be measured for a torque detecting device according to the present invention comprises: a shaft to be measured; exciting means for forming a magnetic circuit having the shaft to be measured as a part of a magnetic path; In manufacturing the shaft to be measured of the torque detecting device including a detecting means for detecting a magnetostrictive component of the shaft, using a material having a high yield point by a surface hardening treatment as a substrate of the shaft to be measured, After the high magnetostrictive material is melted and joined to the surface of the base, at least a portion of the high magnetostrictive material of the measured shaft has a concave portion and / or a convex formed at a predetermined angle with respect to the axial direction of the measured shaft. Forming a shape,
Exposing the base material at least at the bottom of the concave portion,
It is characterized in that the substrate is subjected to a surface hardening treatment through a portion exposed at the bottom of the concave portion, and in the embodiment, the Vickers hardness of the surface at the exposed portion of the bottom of the concave portion is Hv600 or more. In the embodiment, the depth of the effective hardened layer having a Vickers hardness of Hv550 or more in the exposed portion at the bottom of the concave portion is 0.1 mm.
It is characterized in that a surface hardening treatment of 2 mm or more is performed. In the same embodiment, the surface hardening treatment includes chemical heat treatment such as carburizing, carbonitriding, nitriding and the like, shot peening, cold rolling, cold rolling. Characterized by at least one selected from physical machining such as cold forging and stretching, and the above-described configuration of the invention relating to the method of manufacturing the shaft to be measured for the torque detecting device described above. This is a means for solving the conventional problem described above.

Further, in the method of manufacturing a shaft to be measured for a torque detecting device according to the present invention, a buildup layer made of a high magnetostrictive material is formed on the surface of a steel shaft base, and an uneven portion is formed on the buildup layer. In manufacturing the formed shaft to be measured , a high magnetostrictive material is formed on the surface of the steel shaft base by using a carburized compatible steel material for the steel shaft base.
Forming a build-up layer consisting of, forming the concave portion of the uneven portion by cutting the build-up layer until the surface of the steel material is exposed, and then performing carburizing treatment to thereby form the bottom of the concave portion.
Hardens by carburizing the surface of the substrate through the exposed part
It is characterized in that it is configured to be.

Furthermore, the method of manufacturing a shaft to be measured for a torque detecting device according to the present invention comprises forming a build-up layer made of a high magnetostrictive material on the surface of a steel shaft base, and forming an uneven portion on the build-up layer. In manufacturing the formed shaft to be measured , a high magnetostrictive material is applied to the surface of the steel shaft base by using a nitride compatible steel material for the steel shaft base.
Forming a build-up layer consisting of, forming the concave portion of the uneven portion by cutting the build-up layer until the surface of the steel material is exposed, and then performing a nitriding treatment to form the bottom of the concave portion.
The surface of the substrate is cured by nitriding through the exposed part
It is characterized in that it is configured to be.

In the present invention, the shaft to be measured is obtained by melting and joining a high magnetostrictive material to the surface of a base material made of a material having a high yield point by a surface hardening treatment. Here, as the base material to be used, steel materials for machine structures stipulated in JIS, for example, carbon steel materials for machine structures (SC materials and the like), alloy steel materials for machine structures (SCr materials, SCM materials, etc.) Material, SNCM material, etc.)
Is used. In addition, as a steel material suitable for nitriding, SA
CM645, SCM56, SCMV2, SAC and the like are used. And the thing which improved the yield point by changing an additive component or composition suitably is used.

The high magnetostrictive material used on the surface of the shaft to be measured includes metal Fe, metal Ni, and Fe—Ni.
Alloys, Fe-Al alloys, Fe-Co alloys, and the like are used, and those having improved magnetostriction and the like by appropriately changing the added components and compositions are used.

It is important that the base material and the high magnetostrictive material are mutually melted and alloyed and joined .

[0021] Then, the substrate material, when it is assumed that the high-magnetostrictive material is melted and bonded to the surface thereof, TIG welding, plasma powder welding, laser welding, electron beam welding of <br/> which means using Can be

At least the portion of the high magnetostrictive material (including only the portion of the high magnetostrictive material and the range from the portion of the high magnetostrictive material to the portion of the base material) of the shaft to be measured obtained by the above materials and the manufacturing method. , With respect to the axis direction of the axis to be measured,
By forming a plurality of concave portions at a predetermined angle in the circumferential direction, a shape magnetic anisotropic portion is provided by forming a plurality of convex portions in the circumferential direction between these concave portions. At least the bottom of the concave portion is formed so that the base material is exposed. After that, the base material is subjected to a surface hardening treatment.

When carburizing is performed in the surface hardening treatment, the depth of the carburized layer is, for example, about 0.5 to 1.2 mm. At this time, since the base material is exposed at the bottom of the concave portion, the exposed portion is carburized. Therefore, the fatigue strength of the shaft to be measured is further improved.

In the case where nitriding is performed in the surface hardening treatment, for example, a temperature of 500 to 550 ° C. and NH ₃
15 to 3 hours in a nitriding atmosphere with a content of 80 to 90%
A nitriding treatment of 0Hr can be employed. At this time,
Since the base material is exposed at the bottom of the concave portion , this base material is exposed.
The exposed portion is nitrided.

[0025]

According to the present inventors, the cause of the above-mentioned conventional problems is that the high magnetostrictive material formed on the surface acts as a barrier for penetration of carbon and nitrogen, and carbon and nitrogen do not reach the internal base material. I knew that carburizing and nitriding were not going to take place.

Therefore, it is sufficient to form a portion where the internal base material is exposed at an appropriate place of the high magnetostrictive material. At that time, the bottom of the concave portion forming the shape magnetic anisotropic portion is used.

In the torque detecting device according to the present invention,
The shaft to be measured is made of a material that has a high yield point due to surface hardening treatment, and a high magnetostrictive material is melted on its surface.
At least a concave portion and / or a convex portion forming a predetermined angle with respect to the axial direction of the measured shaft is formed on at least a portion of the high magnetostrictive material of the measured shaft at least at the bottom of the concave portion. By forming the material so as to be exposed, and thereafter performing a surface hardening treatment through a portion exposed at the bottom of the concave portion, a high yield point of the base material is obtained, and a good torque- The torque measuring device has both output characteristics and sufficient fatigue durability.

That is, since the base material is exposed at the bottom of the concave portion, carbon or nitrogen penetrates into the base material from the exposed portion by surface hardening treatment, for example, carburizing or nitriding treatment. Cures the surface.

In this case, the surface hardness of the exposed part is set to Vvs hardness of Hv6 to be usable in the practical torque range.
Desirably, it is not less than 00. On the other hand, if it is hardened too much, it becomes brittle.

In order to expand the torque range, Hv550
It is desirable that the effective hardened layer depth is 0.2 mm or more.

The surface hardening treatment increases the yield point of the base material, so that stable torque-output characteristics can be obtained from a low torque range to a high torque range.

In the present invention, since the purpose is to increase the yield point of the base material supporting the high magnetostrictive material, that is, to harden the surface , the base material is exposed at the bottom of the concave portion, and shot peening, cold rolling, It is also effective to perform surface hardening by physical machining such as cold forging. In this case, the hardening action by the mechanical processing is not necessarily required for the high magnetostrictive material, but there is no actual harm even if the hardening action is received simultaneously with the base material.

[0033]

Next, an embodiment of a torque detecting device according to the present invention will be described together with a comparative example.

(Embodiment 1) FIG. 1 shows an embodiment of a torque detecting device according to the present invention. This torque detecting device 1 is made of a material having a high yield point by a surface hardening treatment. Is provided as a base 2a, the surface of which is provided with a shaft 2 to which a high magnetostrictive material 2b is melted and bonded , and the portion of the shaft 2 to be measured which is the high magnetostrictive material 2b is provided with the axis of the shaft 2 to be measured. By forming a plurality of concave portions 3a, 3b at a predetermined angle symmetrical with respect to the direction in the circumferential direction, a plurality of convex portions 4a, 4b are formed in the circumferential direction between these concave portions 3a, 3b. Thus, the shape magnetic anisotropic portion is provided, and the coils 5a and 5b are arranged on the outer peripheral side of the measured shaft 2 with the gap 6 opposed to the shape magnetic anisotropic portion, and are provided outside the coils 5a and 5b. A structure having a yoke 7 made of a high magnetic permeability material is provided. Things.

In this case, the coils 5a and 5b have the same circuit configuration as that shown in FIG.
In addition, an exciting unit that forms a bridge circuit and forms a magnetic circuit in which the measured shaft 2 is a part of a magnetic path, and a detecting unit that detects a magnetostrictive component of the measured shaft 2 are also used.

FIG. 2 is an enlarged view of a portion of the high magnetostrictive material provided with the shape magnetic anisotropic portion of the shaft 2 to be measured in the torque detecting device 1 having the structure shown in FIG. JIS SCM420 is used as the material of the base 2a of the measurement shaft 2.
A high magnetostrictive material 2b provided on the surface of an alloy steel corresponding to
Fe containing 13% by weight of Al and the balance of Fe
It is assumed that the aluminum alloy is melted and joined on the surface of the base 2a by plasma powder welding.

Thereafter, the outer peripheral portion is cut to a diameter of 31 mm, and the concave portion 3 having a width of 1.0 mm and a depth of 1.5 mm is formed.
a, 3b are circumferentially cut at equal intervals at 32 locations to form relatively convex portions 4a, 4b so that the base material is exposed at least at the bottoms of the concave portions 3a, 3b. A shape magnetic anisotropic portion was provided by 3a, 3b and convex portions 4a, 4b, and this was subjected to gas carburization at 910 ° C. for 2 hours, followed by quenching and tempering to obtain shaft 2 to be measured.

The surface hardness of the concave portion 3a, the substrate material exposed at the bottom of 3b in this case is Vickers hardness Hv710, Vickers hardness Hv550 or more effective case depth was a 0.85 mm.

What is important here is that, as shown in FIG.
The portion of the high magnetostrictive material 2b is extended over a wide range into concave portions 3a,
3b. Then, the width of the convex portions 4a, 4b, the interval between the left and right concave portions 3a, 3b / the convex portions 4a, 4b, and the boundary portions with the base material at both ends and the concave portions 3a, 3b / the convex portions. It is desirable that the distance from each of 4a and 4b be 3 mm or less from the viewpoint of the penetration effect.

In this case, the effective hardened layer depth is variable depending on the processing conditions such as carburization, but is usually 1.5 mm
Since it is appropriate to set the distance within the range from the viewpoint of productivity, it is desirable that the distance penetrating from both sides is 3 mm or less.

As a result, carbon formed by carburizing and hardening penetrates the base material from the bottoms of the concave portions 3a and 3b where the base material is exposed, and as shown in FIG.
The carbon goes around to the lower part of the steel sheet to form a hardened layer (carburized layer) 8. For this reason, the surface portion of the base material is hardened substantially over the entire area, and the yield point is increased, thereby expanding the torque detection range. In this case, the concave portion 3
It is not necessary that the base material portion is exposed at all of the bottoms of a and 3b, and there is no problem even if the high magnetostrictive material 2b remains at a part.

As shown in FIG. 4, the torque-output characteristic of the torque detecting device 1 in this embodiment has a wide range in which the torque is proportional to the output.
In experiments up to fm, it was recognized that good linearity was maintained and no output saturation was observed.

Comparative Example 1 In the conventional torque detecting device 101 shown in FIG.
FIG. 5 is an enlarged view of a portion of the high magnetostrictive material provided with the shape magnetic anisotropic portion of the shaft to be measured 102, and the material of the base 102a of the shaft to be measured JIS SC
Using an alloy steel equivalent to M420, this was
m, and as the high magnetostrictive material 102b provided on this surface, Al: 13% by weight and the balance Fe
It is assumed that the powder was melted and joined on the surface of the base 102a by plasma powder welding using an Fe—Al alloy made of Fe.

Thereafter, the outer peripheral portion is cut to a diameter of 31 mm, and the concave portion 10 having a width of 1.0 mm and a depth of 1.5 mm is formed.
The convex portions 104a and 104b are relatively formed by cutting 32 portions of 3a and 103b at equal intervals in the circumferential direction, and the concave portions 103a and 103b and the convex portion 1 are formed.
Shaped magnetic anisotropic parts were formed by the parts 04a and 104b, and after carburizing and quenching at 850 ° C., the parts were tempered to obtain the shaft to be measured 102.

In this case, since the thickness of the high magnetostrictive material 102b is 2 mm after the outer periphery is cut, the concave portions 103a and 103b having a depth of 1.5 mm are the same as in the previous embodiment.
Is formed, as shown in FIG.
The high magnetostrictive material 102b remains at the bottom of 03b, and the base material 102a is not exposed.

Therefore, the high magnetostrictive material 102b Fe-Al
Hindered by the alloy, the substrate material is not carburized.

Therefore, the yield point is low and the output saturation of the torque-output characteristic occurs at a low torque.

As shown in FIG. 7, the torque-output characteristic of the torque detecting device 101 in Comparative Example 1 is as follows.
The range in which the torque was proportional to the output was narrow, and the output saturation torque was 50 kgfm.

(Evaluation Result 1) As is clear from these results, the torque detecting device 1 according to the present invention can expand the measured torque range 1.8 times as large as the conventional torque detecting device 101. did it.

The shaft 2 to be measured is made of a material having a high yield point by surface treatment such as carburization as a substrate 2a, and a high magnetostrictive material 2b is melted and joined on the surface of the substrate 2a to be integrated. Therefore, even when the fatigue test was performed, no problem such as peeling of the high magnetostrictive material 2b or occurrence of output abnormality was observed, and excellent durability of 100,000 times or more was exhibited.

Example 2 As shown in FIG. 8A, JIS S having a diameter of 30 mm was used.
The steel shaft base 12a made of CM420 is provided with (B-
As shown in 1) and (B-2), a high magnetostrictive material Fe
By overlaying the -65 wt% Ni alloy by powder overlay welding, the overlaid layers 12b, 12b, made of two high magnetostrictive materials having a width of 15 mm, a thickness of approximately 1 mm, and making a round around the shaft, are spaced apart by 8 mm. After forming, in the cutting process, width 2
As shown in (C-1) and (C-2) of FIG. 8, the concave portions 13a and 13b which are inclined with respect to the axial direction have a circumference of And a plurality of relatively convex portions 14a and 14b are formed in the circumferential direction.

Then, by performing gas carburizing under the condition of 850 ° C. × 1 hr, a torque detecting device having a hardened layer (carburized layer) 18 formed at the bottom of the concave portions 13a and 13b as shown in FIG. A shaft to be measured 12 was prepared.

Comparative Example 2 In the same manner as in Example 2, an Fe—Ni alloy was used.
As 1, a cladding layer having a width of 15 mm and a thickness of 1 mm was formed on a steel shaft base made of JIS SCM20 having a diameter of 30 mm to a thickness of 8 m.
After forming two at an interval of m, not by cutting, but by rolling, the width is 2 mm, the axial length is 13 mm, and the depth is 1.2 m.
A plurality of m-shaped concave portions were formed in the circumferential direction, whereby a plurality of relatively convex portions were formed in the circumferential direction. Comparative Example 2
As -2, one having a diameter of 50 mm was also manufactured.

(Evaluation Result 2) Fatigue strength was determined for the shafts to be measured for the torque detecting devices of Example 2 and Comparative Example 2, and the results are shown in FIG.

As shown in FIG. 9, the sample of Example 2 not only exhibits much better fatigue strength than the sample of Comparative Example 2-1 having a diameter of 30 mm, but also has a diameter of 50 m of Comparative Example 2-2.
m exhibited better fatigue strength than those of
Assuming that the weight of the comparative example 2-2 having a diameter of 50 mm is “1”, the weight of the second example is only “about 0.35”, so the measured shaft for the torque detecting device of the second example is used. According to this, a significant reduction in weight has become possible.

When the hardness at the bottom of the concave portions 13a and 13b of the measured shaft 12 for the torque detecting device of Example 2 was measured, it was found that the Bekas hardness Hv was 700 or more. The depth of the carburized layer 18 is 0.5 to
1.2 mm. Then, when the torque was measured by the measured shaft 12 for a torque detecting device, it was found that the torque had a practically sufficient magnetostriction sensitivity.

In addition, the improvement of the fatigue strength is achieved by the concave portion 13.
It is considered that the hardness at the bottoms of a and 13b is at least 600 or more in Vickers hardness Hv. Therefore, the same operation and effect can be expected by carbonitriding or nitriding instead of carburizing.

Therefore, the reaction was carried out at 510 ° C. for 27 hours.
The Vickers hardness Hv at the bottom of the concave portion is 600 under the condition that the decomposition N is diffused in an atmosphere containing 80% of ₃ gases.
The above-mentioned shaft 12 to be measured for the torque detecting device was manufactured, and the fatigue strength was measured for the same. As a result, the same good results as those obtained by carburization shown in FIG. 9 were obtained. In addition, the magnetostriction sensitivity did not decrease even by nitriding.

As described above, according to the measured shaft 12 for the torque detecting device of the second embodiment, even though it is thin, it has a sufficient fatigue strength, and it is possible to perform highly reliable torque measurement for a long period of time. Moreover, according to the manufacturing method employed in the second embodiment, the magnetostriction sensitivity is not impaired.

[0060]

The shaft to be measured for the torque detector according to the present invention is obtained by melting and joining a high magnetostrictive material to the surface of a steel shaft base having a high yield point by surface hardening treatment. A concave portion and / or a convex portion at a predetermined angle with respect to the axial direction of the steel shaft is formed at least in a portion of the high magnetostrictive material of the shaft, and at least a bottom of the concave portion is the base material portion. Is exposed, and the substrate is subjected to a surface hardening treatment through a portion exposed at the bottom of the concave portion. In an embodiment, the Vickers hardness of the surface of the substrate material portion exposed at the bottom of the concave portion is formed. Saga Hv60
The torque detecting device according to the present invention comprises: a shaft to be measured; exciting means for forming a magnetic circuit having the shaft to be measured as a part of a magnetic path; In the torque detecting device provided with detecting means for detecting the magnetostrictive component of the above, the shaft to be measured is made of a material having a high yield point by surface hardening treatment, and the high magnetostrictive material is melted and joined to the surface thereof. A concave portion and / or a convex portion forming a predetermined angle with respect to the axial direction of the measured shaft is formed at least in a portion of the high magnetostrictive material of the measured shaft, and at least a bottom of the concave portion is formed. The base material is exposed, and the base is subjected to a surface hardening treatment through a portion exposed at the bottom of the concave portion. The measured shaft is used, and the measured shaft according to the present invention is further used. In the manufacturing method of Manufacturing the shaft to be measured of a torque detecting device comprising: an exciting unit that forms a magnetic circuit having the shaft to be measured as a part of a magnetic path; and a detecting unit that detects a magnetostrictive component of the shaft to be measured. In this regard, a material having a high yield point by surface hardening treatment is used as the base of the measured shaft, and a high magnetostrictive material is melted and joined to the surface of the base. At least in the portion of the high magnetostrictive material, a concave portion and / or a convex portion forming a predetermined angle with respect to the axial direction of the axis to be measured is formed, and the base material is exposed at least at the bottom of the concave portion. Since the surface hardening treatment is performed on the base through the exposed portion at the bottom of the concave portion, the range of the base material that can be used as the measured shaft of the torque detecting device can be expanded, and the torque-output can be increased. Characteristic saturation output The torque can be greatly improved from low torque range to high torque range, and peeling of high magnetostrictive material hardly occurs even when high torque is repeatedly received. The durability is excellent, and a remarkably excellent effect that stable torque-output characteristics can be obtained for a long period of time is brought about.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a torque detection device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an enlarged portion of a high magnetostriction material of a shaft to be measured in the torque detection device shown in FIG.

FIG. 3 is an explanatory diagram showing an enlarged cross section of the measured shaft shown in FIG. 2;

FIG. 4 is a graph illustrating an example of a torque-output characteristic of the torque detection device according to the first embodiment of the present invention.

5 is an explanatory diagram showing, in an enlarged manner, a portion of a high magnetostriction material of a shaft to be measured in the torque detection device shown in FIG.

FIG. 6 is an explanatory diagram showing an enlarged cross section of the shaft to be measured shown in FIG. 5;

FIG. 7 is a graph showing an example of a torque-output characteristic of the torque detection device according to Comparative Example 1 of the present invention.

FIG. 8 is an explanatory view sequentially showing a manufacturing process of a shaft to be measured for a torque detecting device in Embodiment 2 of the present invention.

FIG. 9 is a graph showing the results of examining the fatigue strength of a shaft to be measured for a torque detection device in Example 2 and Comparative Example 2 of the present invention.

FIG. 10 is an explanatory diagram illustrating an example of a conventional torque detection device.

FIG. 11 is an explanatory diagram showing an example of a circuit forming an exciting unit and a detecting unit of the torque detecting device.

FIG. 12 is a graph showing an example of a torque-output characteristic of a conventional torque detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torque detecting device 2 Measured shaft 2a Base of measured shaft 2b High magnetostrictive material 3a, 3b Concave portion 4a, 4b Convex portion 5a, 5b Coil (excitation means and detection means) 6 Gap 7 Yoke 8 Hardened layer (carburized layer) 12) Shaft to be measured 12a Steel shaft base 12b Overlay layer made of high magnetostrictive material 13a, 13b Concave portion 14a, 14b Convex portion 18 Hardened layer (carburized layer)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Munekatsu Shimada 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. 98 No. 3 (72) Inventor Shigeo Hanashima 1-7 Katsuyama, Arao-cho, Tokai-shi, Aichi Prefecture (56) References JP-A-3-87623 (JP, A) JP-A-2-107910 (JP, A JP-A-2-90030 (JP, A) JP-A-1-117378 (JP, A) JP-A-63-297545 (JP, A) JP-A-63-81993 (JP, A) 35768 (JP, U) Japanese Utility Model 1-503403 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G01L 3/10

Claims (12)

(57) [Claims] A high magnetostrictive material is melted and joined to a surface of a steel shaft base having a high yield point by a surface hardening treatment, and at least a high magnetostrictive material of the steel shaft is formed. A concave portion and / or a convex portion forming a predetermined angle with respect to the axial direction of the steel shaft, and at least a bottom portion of the concave portion has the base material portion exposed, A shaft to be measured for a torque detecting device, wherein a surface hardening treatment is applied to a base through a portion exposed at a bottom of the portion. 2. The measured shaft for a torque detecting device according to claim 1, wherein the Vickers hardness of the surface of the base material portion exposed at the bottom of the concave portion is Hv600 or more. 3. A torque detecting device comprising: a shaft to be measured; an exciting unit for forming a magnetic circuit having the shaft to be measured as a part of a magnetic path; and a detecting unit for detecting a magnetostrictive component of the shaft to be measured. In the apparatus, the measured shaft is a material which has a high yield point due to surface hardening treatment, and a high magnetostrictive material is melted and joined to the surface of the base, and at least a portion of the high measured magnetostrictive material of the measured shaft is used. Forming a concave portion and / or a convex portion at a predetermined angle with respect to the axial direction of the axis to be measured, wherein at least the bottom of the concave portion has the base material exposed, and the bottom of the concave portion has A torque detecting device using a shaft to be measured whose surface is subjected to a surface hardening treatment through an exposed portion. 4. A bead on a surface of a portion exposed at the bottom of the concave portion.
Vickers torque detecting apparatus according to claim 3, hard Saga Hv600 or der wherein Rukoto. 5. A portion exposed at the bottom of the concave portion Vickers
Scan torque detecting apparatus according to claim 3 or 4 Hardness Hv550 or more effective hardened layer depth, characterized in der Rukoto than 0.2 mm. 6. The surface hardening treatment is at least one selected from chemical heat treatment such as carburizing, carbonitriding, nitriding, and physical machining such as shot peening, cold rolling and cold forging. The torque detecting device according to any one of claims 3 to 5 , characterized in that: 7. A torque detecting device comprising: a shaft to be measured; exciting means for forming a magnetic circuit having the shaft to be measured as a part of a magnetic path; and detecting means for detecting a magnetostrictive component of the shaft to be measured. In manufacturing the shaft to be measured in the apparatus, a material having a high yield point by surface hardening treatment is used as a base of the shaft to be measured, and a high magnetostrictive material is melted on the surface of the base.
After joining , a concave portion and / or a convex portion at a predetermined angle with respect to the axial direction of the measured shaft are formed at least in the high magnetostrictive material portion of the measured shaft. A method for manufacturing a shaft to be measured for a torque detecting device, wherein the base material is exposed at a bottom portion, and a surface hardening process is performed on the base material through a portion exposed at a bottom portion of the concave portion. 8. The surface of the surface at the exposed portion at the bottom of the concave portion .
The method for manufacturing a shaft to be measured for a torque detecting device according to claim 7, wherein a surface hardening treatment is performed so that Vickers hardness becomes Hv600 or more . 9. A vicker at an exposed portion at the bottom of the concave portion.
Over scan hardness Hv550 or more effective case depth is 0.2m
production method of the measurement axis torque detecting apparatus according to claim 7 or 8, characterized by applying surface hardening treatment to be more m. 10. The surface hardening treatment is at least one selected from chemical heat treatment such as carburizing, carbonitriding, nitriding, and physical machining such as shot peening, cold rolling and cold forging. 10. The method of manufacturing a shaft to be measured for a torque detecting device according to claim 7, wherein: 11. A carburized layer is formed on a surface of a steel shaft base when forming a build-up layer made of a high magnetostrictive material on a surface of the steel shaft base and forming an uneven portion on the build-up layer. Using a compatible steel material on the surface of the steel shaft base
Forming a buildup layer, forming the concave portion of the uneven portion by cutting the overlay layer until the surface of the steel material is exposed, and then exposed at the bottom of the concave portion by performing carburizing treatment .
A method for manufacturing a shaft to be measured for a torque detecting device, wherein the surface of a base is hardened by carburization through a portion . 12. A method for manufacturing a shaft to be measured having a build-up layer made of a high magnetostrictive material on a surface of a steel shaft base and forming an uneven portion on the build-up layer, wherein the steel shaft base is nitrided. Using a compatible steel material on the surface of the steel shaft base
An embossed layer was formed, and the overlaid layer was cut until the steel material surface was exposed to form a concave portion of the uneven portion, and then exposed at the bottom of the concave portion by performing a nitriding treatment .
A method for manufacturing a shaft to be measured for a torque detecting device, wherein a surface of a base is hardened by nitriding through a portion .