JP2856496B2 - Corrosion resistant structure of torque sensor shaft - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant structure of a torque sensor shaft used for a torque sensor that measures the torque of a rotating shaft in a non-contact manner.

2. Description of the Related Art Conventionally, with respect to the corrosion resistance of such a torque sensor shaft, plating or baking coating is generally applied to the corrosion resistance of a general rotating shaft.

However, when these plating and baking are applied to a power transmission shaft such as a torque sensor shaft, when a stress is repeatedly applied, a micro crack is first generated in the anticorrosion coating, and then a macro crack is generated. It's easy to do. And, from the gaps of these cracks, corrosive components such as corrosive gas, water vapor and water enter the shaft surface and often corrode the shaft.

In particular, the magnetostrictive torque sensor shaft is often driven at a relatively high frequency of 10 to 100 kHz, so that the skin depth through which the magnetic flux passes is generally less than about 100 μm below the outermost surface layer of the shaft. It is. Therefore, in order to stably maintain the performance of the magnetostrictive torque sensor for a long period of time, there is a problem that the corrosion of a portion within a depth of 100 μm from the outermost surface layer must be ensured.

Accordingly, an object of the present invention is to solve such a problem and to surely prevent corrosion of a magnetostrictive torque sensor shaft.

Means for Solving the Problems In order to achieve this object, the present invention provides an anticorrosion substance having a non-magnetic and viscous insulating or defective conductor on the outermost surface layer of a magnetostrictive torque sensor shaft. Is applied, and the outer surface of the applied anticorrosive substance is coated with a nonmagnetic and insulating coating material.

According to such a configuration, the outermost surface layer that is most important for the magnetostrictive torque sensor shaft is a viscous or fluid insulator or a poor conductor and a nonmagnetic anticorrosive substance coating film. Will be covered. Therefore, even if stress is repeatedly applied, due to the fluidity of the anticorrosion substance,
The occurrence of microcracks and the like is prevented.

Since the outer surface of the anticorrosion substance is covered with the coating material, even if the torque sensor shaft is operated for a long time, the anticorrosion substance does not evaporate or dry, and micro-cracks are generated due to the evaporation and drying of these anticorrosion substances. Is reliably prevented.

As a result, the outermost surface layer of the torque sensor shaft is protected from corrosion for a long time.

First Embodiment In FIG. 1, reference numeral 1 denotes a torque sensor shaft through which torque is transmitted. A pair of magnetic anisotropic parts 2 and 3 are formed on the surface of the torque sensor shaft 1 by machining grooves or the like.
Numeral 3 is configured to be inclined in opposite directions to the axis. A cylindrical case 5 is supported via a pair of bearings 4 on the outer periphery of the shaft 1 at the portion where the magnetic anisotropic parts 2 and 3 are formed. Inside the case 5, a cylindrical shield yoke 6 is provided. Further, inside the shield yoke 6, a pair of excitation coils 7, 7 and a pair of detection coils 8, 8 are provided. The excitation coils 7, 7 and the detection coils 8, 8 are arranged corresponding to the magnetic anisotropic parts 2, 3, respectively.

The surface of the outermost layer of the shaft 1 between the bearings 4.4 is coated with an anticorrosive substance 9. The anticorrosion substance 9 is made of a nonmagnetic insulator or a defective conductor, and is made of a material having a certain viscosity. For example,
A rust-preventive oil is suitable.

The outer surface of the anticorrosion substance 9 is covered with a coating material 10. The coating material 10 is formed of a film body made of a non-magnetic insulator, and is formed of, for example, a tubular heat-shrinkable resin film. The end portion 11 of the coating material 10 is fixed to the end surface of the bearing 4 by hitting the end surface of the inner race 4a.

FIG. 2 shows another example of the fixing structure of the end portion 11 of the coating material 10. Here, a protrusion 12 is formed on the outer periphery of the shaft 1, and the end 11 of the coating material 10 is fixed to a side surface of the protrusion 12.

FIG. 3 shows still another example of the fixing structure of the end portion 11 of the coating material 10. Here, the end 11 of the covering material 10 is arranged so as to cover the outer peripheral surface of the projection 12 and is fixed to the projection 12.

According to such a configuration, the outermost surface layer of the shaft 1 is covered with the anticorrosive substance 9 having viscosity.
Even if stress is repeatedly applied to the shaft 1, it is possible to prevent corrosion of the shaft 1 without observing the occurrence of microcracks or the like due to the fluidity of the anticorrosion substance 9. Further, since the outer surface of the anticorrosion substance 9 is covered with the coating material 10, even if the torque sensor shaft 1 is operated for a long time, the anticorrosion substance 9 is prevented from being evaporated or dried. For this reason, generation of microcracks in the anticorrosive substance 9 based on the evaporation and drying is prevented.

As a result, the outermost surface layer of the torque sensor shaft 1 is prevented from being corroded for a long time, and the long-term stability of the sensor is ensured.

The end 11 of the coating 10 is the bearing 4 shown in FIG.
2 and 3, the evaporation and drying of the anticorrosive substance 9 are reliably prevented even at the end 11.

Effects of the Invention As described above, according to the present invention, since a viscous anticorrosive substance is applied to the outermost surface layer of the torque sensor shaft, even if a stress is repeatedly applied to the shaft, the anticorrosive substance has microcracks or the like. Generation can be prevented. further,
Since the outer surface of the anticorrosion substance is covered with the coating material, even if the torque sensor shaft is operated for a long time, the anticorrosion substance does not evaporate or dry, and the generation of microcracks based on the evaporation or drying can be prevented. As a result, the outermost surface layer of the torque sensor shaft can be protected from corrosion for a long time, and the sensor characteristics can be stable for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a corrosion-resistant structure of a torque sensor shaft according to one embodiment of the present invention. FIGS. 1 ... Torque sensor shaft, 2,3 ... Magnetic anisotropic part, 4 ...
Bearing, 9 anticorrosive substance, 10 coating material, 11 end portion, 12 projection.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 3/10

Claims (3)

(57) [Claims] A non-magnetic and viscous anticorrosive substance, which is an insulator or a defective conductor, is applied to the outermost surface layer of a magnetostrictive torque sensor shaft, and the outer surface of the applied anti-corrosion substance is coated with a non-magnetic material. A corrosion-resistant structure for a torque sensor shaft, characterized by being coated with a coating material having insulation properties. 2. The sensor shaft according to claim 1, wherein the sensor shaft has a projection on a surface thereof, and a coating material is fixed to the projection.
Corrosion resistant structure of the torque sensor shaft described. 3. A corrosion-resistant structure for a torque sensor shaft according to claim 1, wherein said sensor shaft is fitted in said coil holding bearing, and said coating material is fixed to an end face of said coil holding bearing.