阅读说明：本技术 传感器帽用螺母及传感器帽 (Nut for sensor cap and sensor cap ) 是由 上愿豊 于 2021-03-25 设计创作，主要内容包括：本发明的目的是在抑制制造成本的上升而得到充分的防腐蚀性的同时、在2021年7月21日以后也满足上述RoHS指令。一种在被固定在传感器帽上的状态下使用的螺母(1)。上述传感器帽被安装在汽车的车轮用轴承装置的轴承的外轮上。上述传感器帽具有保持磁传感器的传感器支架部。螺母(1)由钢铁构成,通过将螺栓与螺纹部(3)螺合,能够安装上述磁传感器。在螺母(1)的表面上,具有镍共析率为8％～18％的锌镍合金镀层(5)。(The object of the present invention is to obtain sufficient corrosion resistance while suppressing an increase in manufacturing cost, and to satisfy the RoHS directive even after 7/21/2021. A nut (1) is used in a state of being fixed to a sensor cap. The sensor cap is attached to an outer ring of a bearing device for a wheel of an automobile. The sensor cap includes a sensor holder portion that holds the magnetic sensor. The nut (1) is made of steel, and the magnetic sensor can be attached by screwing a bolt into the threaded portion (3). A zinc-nickel alloy plating layer (5) having a nickel eutectoid rate of 8% to 18% is provided on the surface of the nut (1).)

1. A nut for a sensor cap, which is used in a state of being fixed to the sensor cap, is characterized in that,

the sensor cap is mounted on an outer ring of a bearing device for a wheel of an automobile and has a sensor holder portion for holding a magnetic sensor,

the nut is made of steel, the magnetic sensor can be attached by screwing a bolt into a threaded portion of the nut, and a zinc-nickel alloy plating layer having a nickel eutectoid rate of 8% to 18% is provided on a surface of the nut.

2. The nut for a sensor cap according to claim 1,

the nickel eutectoid rate of the zinc-nickel alloy coating is 12-18%.

3. A sensor cap is characterized in that a cap body is provided with a plurality of through holes,

a nut for a sensor cap according to claim 1 or 2.

Technical Field

The present invention relates to a nut used for a sensor cap attached to an outer ring of a bearing of a wheel bearing device.

Background

There is a wheel bearing device including a rotation speed detection device in a rolling bearing (hub bearing) for supporting a wheel of an automobile. In such a wheel bearing device, a magnetic encoder in which N poles and S poles are alternately arranged at regular intervals in the circumferential direction is attached to an inner ring at one end in the axial direction of the bearing, and a magnetic sensor for detecting the rotation of the magnetic encoder is attached to an outer ring side of the bearing so as to face the magnetic poles of the magnetic encoder (see, for example, patent documents 1 to 3).

In patent documents 1 to 3, a sensor cap having a sensor holder portion for holding the magnetic sensor is attached to an outer ring at one end portion in the axial direction of the bearing. A nut is embedded or attached in or fixed to the synthetic resin body of the sensor cap, and the magnetic sensor is fixed to the sensor cap by a female screw of the nut.

As the above nut, a cap nut type nut 23 formed in a bag shape as a whole is used in patent document 1, and an embedded nut 1 and a nut 20 having a through hole are used in patent documents 2 and 3.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006 and 009889

Patent document 2: japanese patent laid-open publication No. 2018-071775

Patent document 3: japanese patent No. 4576992

Disclosure of Invention

Problems to be solved by the invention

The nut is fixed to a sensor cap that is a chassis component of an automobile, and a bolt that fixes the magnetic sensor is screwed to the nut in a state where one end surface and a screw hole of the nut are exposed to the outside. Therefore, corrosion resistance is required for the nut.

Patent document 2 describes that in order to provide corrosion resistance to the nut, it is preferable to use brass as the material, and in the case of manufacturing the nut from an iron-based material, it is preferable to perform plating treatment ([ 0030] of patent document 2).

Patent document 3 describes that the nut is coated with a zinc plating layer by applying a zinc plating treatment (electrogalvanizing treatment) to impart corrosion resistance to the nut (patent document 3 [0016 ]).

The surroundings of the wheels of an automobile are exposed to an environment in which salt water containing a snow melting agent (calcium chloride) is splashed, and high corrosion resistance is required. Patent documents 2 and 3 describe the above-described plating treatment, but do not describe the plating treatment in detail. That is, in the conventional art, the plating layer provided on the nut for a sensor cap is not optimized. For example, even if a galvanized coating is provided on a nut made of steel for rust prevention, a sufficient rust prevention effect may not be exhibited.

Brass nut stock is expensive and has less strength than steel nuts. In addition, in brass containing 20 wt% or more of zinc as an alloy of copper and zinc, 1.8 to 3.7 wt% of lead is added to free-cutting brass (C3601, C3602, C3603, C3604) of JIS H3250 for improving machinability.

Copper alloys containing 0.1 wt% or more of lead are currently applied to the foreign materials in accordance with the RoHS (restriction of use of specific hazardous substances) directive, which is a chemical restriction concerning electric and electronic equipment, but are expected to be forbidden at 21/7/2021. Therefore, since the free-cutting brass (C3601, C3602, C3603, C3604) of JIS H3250 contains lead in an amount of 0.1 wt% or more, there is a possibility that the above RoHS directive cannot be satisfied and the brass cannot be exported to the European Union (EU) after 21/7/2021.

The present invention is intended to provide a nut for a sensor cap, which is required to have high corrosion resistance, and which satisfies the RoHS directive described above even after 21/7/2021 while suppressing an increase in manufacturing cost to obtain sufficient corrosion resistance.

Means for solving the problems

The gist of the present invention is as follows.

[ 1 ] A nut for a sensor cap, which is used in a state of being fixed to the sensor cap, wherein the sensor cap is attached to an outer ring of a bearing device for a wheel of an automobile; a sensor holder portion for holding a magnetic sensor; the nut is made of steel; the magnetic sensor can be attached by screwing a bolt into the threaded portion of the nut; the surface of the nut is provided with a zinc-nickel alloy coating layer with a nickel eutectoid rate of 8-18%.

[ 2 ] the nut for a sensor cap according to [ 1 ], wherein the nickel eutectoid rate of the zinc-nickel alloy plating layer is 12% to 18%.

[ 3 ] A sensor cap provided with the sensor cap nut described in [ 1 ] or [ 2 ].

Effects of the invention

According to the sensor cap nut and the sensor cap of the present invention as described above, the sensor cap nut is made of steel. And, on the surface of the nut, there is a zinc-nickel alloy plating layer having a nickel eutectoid rate of 8% to 18%.

Since expensive brass is not used, the manufacturing cost can be reduced. Since lead is not contained, the RoHS command can be satisfied even after 21/7/2021, and thus, export to the European Union (EU) is possible even after 21/7/2021. Since steel has a higher strength than brass, the mounting strength of the magnetic sensor can be improved. By covering the nut made of steel with the zinc-nickel alloy plating layer, high corrosion resistance can be provided. Further, since the zinc-nickel alloy plating layer is a coating containing nickel, the coating has high hardness and therefore has good wear resistance with respect to the bolt for mounting the magnetic sensor.

Drawings

Fig. 1A is a perspective view of a nut for a sensor cap according to an embodiment of the present invention.

Fig. 1B is also a longitudinal sectional view.

Fig. 2A is a perspective view of the sensor cap in which the nut is embedded, as viewed from the inside.

Fig. 2B is a perspective view of the sensor cap in which the nut is embedded, as viewed from the outside.

Fig. 3 is a longitudinal sectional view of the sensor cap.

Fig. 4A is a perspective view showing a modified example of the nut for the sensor cap.

Fig. 4B is also a longitudinal sectional view.

Fig. 5 is a partial longitudinal sectional view of the wheel bearing apparatus.

Description of the reference symbols

1 nut for sensor cap

1A through hole

2A, 2B end

3 screw part

4A knurled part

4B peripheral groove

5 zinc-nickel alloy coating

6 sensor cap

6A fiber-reinforced synthetic resin body

6B metal ring body

7 disk part

8 cylinder part

9 sensor holder

9A sensor mounting hole

10 partition wall

11 bolt

12 magnetic encoder

13 support member

14 magnetic sensor

15 bearing

16 inner wheel

16A inner wheel track surface

17 outer wheel

17A outer wheel driving surface

18 rotating body

19 sealing member

Bearing device for 20-wheel

Axial direction A

IB interior formula

Exterior OB

Detailed Description

Next, the present invention will be described in more detail based on embodiments shown in the drawings. In the present specification, the direction of the rotation axis a of the wheel support bearing device 20 shown in fig. 5 is referred to as the "axial direction", and the direction perpendicular to the axial direction is referred to as the "radial direction".

In the bearing 15 and the sensor cap 6, in a state where the sensor cap 6 is attached to the bearing 15, a direction (outer side) parallel to the axial direction from the vehicle body of the automobile toward the wheel side is referred to as "outward" (see arrow OB in fig. 5), and a direction (inner side) parallel to the axial direction from the wheel of the automobile toward the vehicle body side is referred to as "inward" (see arrow IB in fig. 5).

< nut for sensor Cap >

The nut 1 for a sensor cap according to the embodiment of the present invention shown in the perspective view of fig. 1A and the vertical sectional view of fig. 1B is substantially cylindrical, is made of steel such as carbon steel for cold forging (SWCH material of JIS G3507-2), and has a through-hole 1A and a threaded portion 3. A knurled portion 4A, for example, is formed as a twill on the outer peripheral surface of the nut 1. The knurled portion 4A is formed with irregularities on the surface by pressing a knurling tool while rotating the nut 1 with a lathe or the like, for example. The entire surface of the nut 1 is covered with a zinc-nickel alloy plating layer 5.

The thickness of the zinc-nickel alloy coating 5 is 5-15 μm. In the case where the above thickness is less than 5 μm, the corrosion prevention effect is lacking in the sensor cap as the chassis part of the automobile. When the thickness exceeds 15 μm, the gap becomes small, and the screwing force of the screw becomes large.

The nickel eutectoid ratio of the zinc-nickel alloy plating layer 5 is preferably 8% to 18%, and more preferably 12% to 18%. When the nickel eutectoid ratio is less than 8%, the sensor cap as a chassis part of an automobile lacks an anti-corrosion effect. When the nickel eutectoid ratio exceeds 18%, the quality is excessive, and the cost increases.

< sensor Cap >

The sensor cap 6 in which the sensor cap nut 1 is embedded, which is shown in the perspective views of fig. 2A and 2B and the longitudinal sectional view of fig. 3, is composed of a fiber-reinforced synthetic resin body 6A and a metal ring body 6B.

Here, as the fiber-reinforced synthetic resin of the molded body 6A, for example, a synthetic resin such as polyamide (nylon 6, nylon 66, etc.), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or the like, containing 20 to 70 wt% of glass fiber is used.

The metal ring body 6B is preferably a cold-rolled steel sheet such as SPCC which is a low-carbon steel.

The main body 6A includes a cup-shaped disc portion 7, a cylindrical portion 8, and a sensor holder portion 9 projecting inward (see arrow IB) from the disc portion 7.

The disk portion 7 is formed with a partition wall 10 that is thinner than the other portions and partitions a magnetic encoder 12 and a magnetic sensor 14 (fig. 5).

The sensor holder 9 has a sensor mounting hole 9A into which the magnetic sensor 14 (fig. 5) is inserted while holding a nut 1 into which a bolt 11 (fig. 5) for mounting the magnetic sensor 14 (fig. 5) is screwed.

The nut 1 and the metal ring 6B are insert-molded articles, and are integrated with the fiber-reinforced synthetic resin body 6A by injection molding. As shown in the vertical cross-sectional view of fig. 3, since the synthetic resin enters the knurled portion 4A of the nut 1, the nut 1 embedded in the sensor holder portion 9 is fixed in a state of being prevented from being loosened from the sensor holder portion 9. Further, since the cylindrical portion 8 is surrounded on the outer (indicated by arrow OB) side end portion of the metal ring body 6B, the metal ring body 6B and the fiber-reinforced synthetic resin body 6A are mechanically coupled.

The loosening prevention of the nut 1 is not limited to the method of providing the knurled portion 4A on the outer circumferential surface of the nut 1. As shown in the perspective view of fig. 4A and the vertical cross-sectional view of fig. 4B, a method of providing a circumferential groove 4B on the outer circumferential surface of the nut 1, or a method of providing a flange portion, not shown, on the nut 1 may be used, or a plurality of these loosening prevention means may be used in combination.

As shown in the perspective view of fig. 2A and the vertical cross-sectional view of fig. 3, in the nut 1 embedded in the sensor holder 9 of the sensor cap 6, one end 2A and the screw portion 3 of both end portions 2A and 2B (fig. 1B) in the direction parallel to the axial direction a (fig. 5) are exposed.

< bearing device for wheel of automobile >

As shown in the partial vertical cross-sectional view of fig. 5, the wheel bearing device 20 includes the magnetic encoder 12, the sensor cap 6, the magnetic sensor 14, the seal member 19 disposed at the outer (see arrow OB) side end of the bearing 15, and the like, in addition to the bearing 15 in which the inner ring 16 rotates relative to the outer ring 17.

The bearing 15 includes an inner ring 16 having an inner ring raceway surface 16A formed on an outer circumferential surface thereof, an outer ring 17 having an outer ring raceway surface 17A formed on an inner circumferential surface thereof, and a rotor 18 rotating between the inner ring raceway surface 16A and the outer ring raceway surface 17A.

The magnetic encoder 12 has a structure in which N poles and S poles are alternately arranged at regular intervals in the circumferential direction, and is fixed to the inner ring 16 by a support member 13 located at the end of the bearing 15 on the inward (see arrow IB) side.

The sensor cap 6 is cup-shaped, is attached to the outer ring 17 so as to seal the inner end of the bearing 15, and has a sensor holder 9 that holds the magnetic sensor 14.

The magnetic sensor 14 attached to the sensor holder portion 9 of the sensor cap 6 faces the magnetic encoder 12 via the partition wall 10, and detects the rotation of the magnetic encoder 12.

Since the sensor cap 6 has the partition wall 10 and there is no through hole penetrating in the thickness direction, it is not necessary to incorporate a sealing member such as an O-ring.

Further, since the inner end of the bearing 15 is sealed by the sensor cap 6, pebbles, muddy water, or the like do not collide with the magnetic encoder 12, and thus damage to the magnetic encoder 12 can be prevented.

Further, since the inner side end portion of the bearing 15 is sealed by the sensor cap 6, a sealing member on the inner side of the magnetic encoder 12 is not necessary, and therefore, the rotational torque of the bearing 15 can be reduced by reducing the sliding resistance.

Further, since the sensor cap 6 includes the sensor holder 9, it is possible to eliminate the trouble of the air gap adjustment work of the magnetic encoder 12 and the magnetic sensor 14.

The sensor cap 6 shown in the example of fig. 5 is formed by insert injection molding using a metal ring body 6B and a nut 1 as an insert. The nut 1 may be mounted by insert molding instead of insert molding. In this case, for example, a lower hole for attaching the nut 1 is formed by insert injection molding for molding the sensor cap 6 with the metal ring body 6B as an insert, and the nut 1 is pressed into the lower hole after molding the sensor cap 6. At this time, the nut 1 may be heated to press-fit the resin of the sensor holder 9 while softening it.

< experiment for evaluating Corrosion resistance by Zinc-Nickel alloy coating layer >

As described above, the nut 1 for a sensor cap is made of steel, and the entire surface thereof is covered with the zinc-nickel alloy plating layer 5. An experiment for evaluating the corrosion resistance of the zinc-nickel alloy plating layer 5 was performed.

(examples and comparative examples)

20 nuts in which carbon steel for cold forging was exposed before being coated with the zinc-nickel alloy plating layer 5 were produced, 10 of them were treated as examples in which a zinc-nickel alloy plating layer 5 (nickel eutectoid rate: 12% to 18%) having a thickness of 5 μm was formed on their surfaces, and the remaining 10 were treated as comparative examples in which a zinc plating layer having a thickness of 5 μm was formed on their surfaces.

(Experimental method)

For the nuts of examples and comparative examples, brine (water temperature 35 ℃. + -. 3 ℃ C., brine concentration 5 wt%) was continuously sprayed for 2000 hours.

(evaluation method)

(1) In the experiments of the above experimental method, nuts of examples and comparative examples were observed to evaluate the occurrence of rust.

(2) When white rust occurs, white rust is an oxide that appears by the sacrificial corrosion prevention effect of the zinc plating layer, and does not proceed to the iron substrate, so there is no problem in corrosion resistance. When red rust occurs, the red rust is rust of iron that has progressed to the iron substrate, and therefore there is a problem in corrosion resistance.

(evaluation results)

(1) The nuts of the comparative examples were red-rusted for about 600 hours.

(2) In the nuts of the examples, white rust was generated on the end surfaces and the side surfaces of all the nuts 10 after the experiment of the above experimental method, but red rust was not generated.

(3) Since the nuts of the examples did not suffer from red rust even under severe conditions as in the above-described experimental method, it was found that the nut 1 for a sensor cap, the surface of which was covered with the zinc-nickel alloy plating layer 5, had extremely high corrosion resistance.

The thickness of the zinc-nickel alloy plating layer 5 to be coated on the steel nut is preferably 5 μm or more, and may be 5 to 15 μm as described above, according to the above experiment. The nickel eutectoid rate of the zinc-nickel alloy plating layer 5 was found to have a very high rust prevention effect when it was set to 12% to 18% according to the above experiment, but it had a high rust prevention effect even when it was 8% or more. As described above, if the nickel eutectoid ratio of the zinc-nickel alloy plating layer 5 exceeds 18%, the quality is excessive, and the cost increases.

After the nut made of steel is covered with the zinc-nickel alloy plating layer 5, a 3-valent chromate treatment may be performed, and a chromium-free high corrosion resistance coating treatment or a silicon oxide-based high rust prevention coating treatment may be further performed, so that a protective film may be provided on the surface layer portion of the zinc-nickel alloy plating layer 5. This further increases the corrosion resistance.

< Effect >

By using the nut 1 for a sensor cap made of steel covered with the zinc-nickel alloy plating layer 5, the manufacturing cost can be reduced because expensive brass is not used. Since lead is not contained, the RoHS command can be satisfied even after 21/7/2021, and thus, export to the European Union (EU) is possible even after 21/7/2021. Since steel has a higher strength than brass, the mounting strength of the magnetic sensor 14 can be improved. By covering the nut 1 made of steel with the zinc-nickel alloy plating layer 5, high corrosion resistance can be provided. Further, since the zinc-nickel alloy plating layer 5 is a coating containing nickel, the coating has high hardness and is excellent in wear resistance with the bolt 11 for mounting the magnetic sensor 14.

In the above embodiment, the nut 1 for a sensor cap has the through hole 1A. The sensor cap nut 1 may be a pocket nut type insert nut formed in a pocket shape as a whole.

The above description of the embodiments is illustrative, and not restrictive. Various improvements and modifications can be made without departing from the scope of the present invention.