JP2013139204A - Hub unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hub unit that can suppress the corrosion of a track member even if an inexpensive steel knuckle is adopted.SOLUTION: A hub unit includes: a vehicle body mounting flange for mounting a knuckle 60; a steel outer track member having an inner periphery track surface; an inner track member having an outer periphery track surface; a rolling element disposed between the inner periphery track surface of the outer track member and the outer periphery track surface of the inner track member; and an annular member 50 fit in an inner periphery surface of the knuckle 60, abutted to one side of an end surface of the outer track member in an axial direction, and comprised of a material of which the ionization tendency is higher than that of the outer track member.

Description

  The present invention relates to a hub unit.

  Conventionally, as a hub unit, there is one described in JP 2011-42182 A (Patent Document 1). The hub unit includes an outer ring, a hub ring, an inner ring, a plurality of first balls, and a plurality of second balls, and the inner ring is fitted and fixed to the outer peripheral side of the hub ring. ing. The outer ring has a first raceway surface and a second raceway surface, while each of the hub ring and the inner ring has a single raceway surface.

  The plurality of first balls are arranged in a state of being spaced apart from each other in the circumferential direction while being held by a cage between the first raceway surface of the outer ring and the raceway surface of the hub ring. The second balls are disposed between the second raceway surface of the outer ring and the raceway surface of the inner ring and are spaced apart from each other in the circumferential direction while being held by a cage.

  The outer ring has a vehicle body mounting flange, and an aluminum knuckle is attached to the vehicle body mounting flange with a bolt. The hub wheel has a wheel mounting flange, and a wheel is mounted on the wheel mounting flange via a brake rotor.

JP 2011-42182 A

  However, recently, steel material is sometimes used instead of aluminum as a knuckle material on the vehicle body side due to low cost.

  In this case, the ionization tendency of the material of the knuckle and the ionization tendency of the material of the steel hub unit become the same level, and the problem that the hub unit rusts due to the failure to realize the preferential corrosion of the knuckle is not solved. Discovered by the inventor.

  When aluminum knuckles are used, the knuckles corrode preferentially over the steel hub unit due to the higher ionization tendency of aluminum than the steel ionization tendency. It was also found that corrosion of a steel hub unit that requires high dimensional accuracy and is expensive is suppressed.

  Accordingly, an object of the present invention is to provide a hub unit that can suppress the corrosion of the raceway member even when an inexpensive steel knuckle is employed.

In order to solve the above problems, the hub unit of the present invention is:
A steel outer race member having a vehicle body mounting flange for attaching a knuckle and an inner circumferential raceway surface;
An inner race member having an outer raceway surface;
A rolling element disposed between the inner circumferential raceway surface of the outer raceway member and the outer circumferential raceway surface of the inner raceway member;
An annulus made of a material that is fitted to the inner peripheral surface of the knuckle, contacts the end surface on one axial side of the outer race member, and has a higher ionization tendency than the ionization tendency of the material of the outer race member And a member.

  The annular member includes a substantially annular member. That is, in the annular member, the circumferential direction of the member having a closed curved surface that defines the through hole, such as a member having a closed curved surface that defines the through hole, as well as a C-shaped member in a cross section perpendicular to the axial direction. A member having a notch at one location is also included.

  According to the present invention, the annular member made of a material having a higher ionization tendency than the steel material that is the material of the outer race member is configured to contact the end surface in the axial direction of the outer race member. Can be preferentially corroded, and corrosion of the outer race member can be suppressed. Therefore, even if the knuckle for attaching the outer race member to the vehicle body is an inexpensive steel knuckle, corrosion of the expensive outer race member can be suppressed.

In one embodiment,
The inner diameter of the annular member is smaller than the inner diameter of one end face in the axial direction of the outer race member.

  According to the embodiment, the inner diameter of the annular member is larger than the inner diameter of the end surface on one side in the axial direction of the outer race member, and therefore when the seal member is press-fitted into the inner peripheral surface of the outer race member from the annular member side. The annular member does not get in the way, and the seal member can be smoothly fixed to the inner peripheral surface of the outer race member.

  Further, according to the above embodiment, since the inner diameter of the annular member is larger than the inner diameter of the end surface on one side in the axial direction of the outer race member, the foreign matter from the inner circumferential surface of the annular member to the inner circumference side of the outer race member The movement of (dust and muddy water) can be suppressed. Therefore, it is possible to suppress the biting of foreign matter in the seal member attached to the inner peripheral side of the outer race member, and to suppress rusting of the pulsar ring when the pulsar ring of the rotational speed detection device is fixed to the seal member.

  If the inner diameter of the annular member is smaller than the inner diameter of one end surface of the outer race member in the axial direction, the annular member is in contact with the outer race member, so that the outer race from the inner circumference surface of the foreign member annular member. The movement of the member by the centrifugal force toward the inner peripheral side makes it easy for foreign matter in the seal member to be caught and pulsar ring rusting to occur.

In one embodiment,
The annular member can suppress corrosion of the end surface of the outer race member and has a corrosion suppression layer that contacts the end surface of the outer race member.

  When two members with different ionization tendency are in contact, corrosion of the contact surface of a member with a high ionization tendency occurs preferentially, a gap is generated between the contact surfaces of both members, and salt water or the like is generated in the gap. As a result, the contact surfaces of both members are easily corroded.

  According to the embodiment, since the annular member can suppress corrosion of the end surface of the outer race member and has the corrosion suppression layer in contact with the end surface of the outer race member, the annular member and the outer race Crevice corrosion between the contact surfaces with the member can be suppressed, and corrosion of the outer race member can be further suppressed.

  According to the present invention, even if an inexpensive steel knuckle is employed, it is possible to realize a hub unit that can suppress corrosion of the raceway member and has a long life.

It is sectional drawing of the axial direction of the hub unit of one Embodiment of this invention. FIG. 2 is an enlarged cross-sectional view around the outer ring in FIG. 1. It is sectional drawing of the radial direction of an annular member. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, and is a schematic cross-sectional view in the axial direction of the annular member. It is a schematic cross section of a knuckle and an annular member.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view in the axial direction of a hub unit according to an embodiment of the present invention.

  The hub unit includes an inner shaft 1, a first inner ring 2 as an inner race member, a second inner ring 3 as an inner race member, an outer ring 4 as an outer race member, and a plurality of first wheels as rolling elements. A ball 5, a plurality of second balls 6 as rolling elements, and a rotation speed detection device 7 are provided. Each of the inner shaft 1, the first inner ring 2, the second inner ring 3, and the outer ring 4 is made of carbon steel as an example of a steel material.

  The inner shaft 1 has a disk-shaped wheel mounting flange 15 that extends in the radial direction for mounting a wheel (not shown) directly or indirectly at an end portion on the wheel side in the axial direction. An end surface on the outer side in the axial direction of the wheel mounting flange 15 is a wheel mounting surface 19. A plurality of bolt insertion holes 17 are formed on the concentric circle of the wheel mounting flange 15. Bolts are press-fitted into the respective bolt insertion holes 17 with their shaft portions facing outward in the axial direction of the wheel rolling bearing device. The inner shaft 1 has an annular groove 20, and the annular groove 20 is located on one side of the outer peripheral surface of the inner shaft 1 in the axial direction. The annular groove 20 has a bottom surface formed of a cylindrical surface. The annular groove 20 is open on one side in the axial direction and outward in the radial direction.

  The first inner ring 2 is press-fitted and fixed to the other side of the annular groove 20 in the axial direction, while the second inner ring 3 is press-fitted and fixed to one side of the annular groove 20 in the axial direction. The first inner ring 2 has an angular track groove 21 as an example of an outer raceway surface on its outer peripheral surface, and the second inner ring 3 has an angular track groove as an example of an outer raceway surface on its outer peripheral surface. 22.

  The outer ring 4 has a vehicle body mounting flange 43 to be attached to the vehicle body at one end in the axial direction of the outer peripheral surface, and a cast iron knuckle 60 is attached to the vehicle body mounting flange 43 by a bolt 61. It is attached. The outer ring 3 has an angular first track groove 30 as an example of an inner raceway surface and an angular second track groove 31 as an example of an inner raceway surface on the inner peripheral surface thereof. Yes. The first raceway groove 30 is located radially outward of the raceway groove 21 of the first inner ring 2, while the second raceway groove 31 is radially outward of the raceway groove 22 of the second inner ring 3. Is located.

  The plurality of first balls 5 are spaced apart from each other in the circumferential direction while being held by a cage between the first raceway groove 30 of the outer ring 3 and the raceway groove 21 of the first inner ring 2. The plurality of second balls 6 are disposed between the second raceway groove 31 of the outer ring 3 and the raceway groove 22 of the second inner ring 2 and are spaced apart from each other in the circumferential direction while being held by a cage. Is placed.

  The rotational speed detection device 7 includes a pulser ring (indicated by 40 in FIG. 2) and a magnetic sensor 41 as a rotational speed sensor. A gap between one end in the axial direction of the second inner ring 3 and one end in the axial direction of the outer ring 4 is sealed with an annular seal member 42. The pulsar ring is fixed to the outer end face of the annular seal member 42 in the axial direction.

  The pulsar ring is composed of a plastic magnet ring provided with magnetic poles having different polarities alternately in the circumferential direction. This plastic magnet ring is magnetized to S pole and N pole alternately in the circumferential required angle region using a synthetic metal injection molded product mixed with magnetic powder or a magnetic metal material such as sintered ferrite as a base material. Is formed.

  Further, the magnetic sensor 41 is fixed to the vehicle body so that the sensor surface is opposed to the axial end surface of the pulsar ring in the axial direction. The magnetic sensor 41 is composed of a Hall IC. This Hall IC has a structure in which an IC chip is molded with a protective cover made of a synthetic resin.

  When the pulsar ring rotates synchronously with the second inner ring 3 along with the rotation of the second inner ring 3, the magnetic poles of the pulsar ring sequentially face the non-rotating magnetic sensor. Here, the magnitude of the magnetic field (line of magnetic force) generated between a plurality of pairs of magnetic poles of the pulsar ring periodically increases and decreases in the circumferential direction, and the direction of the magnetic field (line of magnetic force) is alternately reversed in the circumferential direction. Therefore, the direction of the magnetic field passing through the magnetic sensor sequentially rotates with a period corresponding to the rotation speed as the pulsar ring rotates. The magnetic sensor 41 detects a periodic inversion of the direction of the magnetic field, and detects a pulse signal having a frequency corresponding to the rotation speed of pulsar ring.

  The signal from the magnetic sensor 41 is output to a control device (not shown) composed of a microcomputer. The control device detects the vehicle speed by calculating the rotational speed of the wheel based on the signal from the magnetic sensor 41.

  FIG. 2 is an enlarged cross-sectional view around the outer ring 4 of FIG.

  As shown in FIG. 2, the hub unit includes an annular member 50, and the annular member 50 is fitted and fixed to the inner peripheral surface of the knuckle 60. Further, the end surface 63 on the other side in the axial direction of the annular member 50 is in contact with the end surface 62 on one side in the axial direction of the outer ring 4. As shown in FIG. 1, the inner diameter d <b> 2 of the end surface 62 on one side in the axial direction of the outer ring 4 is shorter than the inner diameter d <b> 1 of the annular member 50.

  FIG. 3 is a cross-sectional view of the annular member 50 in the radial direction.

  As shown in FIG. 3, the annular member 50 is a substantially annular member, and has a C-shape in a radial cross section. The annular member 50 has a shape in which a notch 80 exists at one place in the circumferential direction of a member having a closed curved surface that defines a through hole. Referring to FIG. 1, the magnetic sensor 41 is disposed so as to pass through the notch 80.

  FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, and is a schematic cross-sectional view in the axial direction of the annular member 50.

  As shown in FIG. 4, the annular member 50 includes a main body 90 made of aluminum as an example of a material having a higher ionization tendency than the material of the outer race member, and a plating layer 91 as an example of a corrosion inhibiting layer. The plated layer 91 covers the end surface 92 of the main body 90 on the outer ring 4 side. In FIG. 4, the plating layer 91 is exaggerated for easy understanding. The plated layer 91 is in contact with the end surface 62 on one side of the outer ring 4 in the axial direction. The plated layer 91 is made of a material that has a higher ionization tendency than the carbon steel that is the material of the outer ring 4. More specifically, the plated layer 91 is made of a zinc-nickel alloy that can suppress corrosion of the end face 62 on one side in the axial direction of the outer ring 4. It has become.

  In this hub unit, the end face 63 on the other end side in the axial direction of the annular member 50 is brought into contact with the end face 62 on the one end side in the axial direction of the outer ring 4 as follows.

  That is, first, as shown in FIG. 5 showing a half cross-sectional view of the knuckle 60 and the annular member 50, the end surface 63 on the other side in the axial direction of the annular member 50 is on the side of the body mounting flange 43 of the outer ring 4 of the knuckle 60. The annular member 50 is fitted into the inner peripheral surface of the knuckle 60 by press fitting so as to be separated from the end surface 85 by L1 [cm]. Here, referring to FIG. 2, the axial distance from one end surface 88 in the axial direction of the vehicle body mounting flange 43 of the outer ring 4 to one end surface 62 in the axial direction of the outer ring 4 is L2 [cm. L1 is determined so as to satisfy L2 ≧ L1.

  Next, the screw hole indicated by the reference numeral 46 in FIG. 5 and the screw hole of the vehicle body mounting flange 43 indicated by 47 in FIG. 1 are aligned, and the bolt 61 is inserted into these screw holes 46, 47. Tighten the bolt 61. Here, since L2 ≧ L1, while the bolt 61 is being tightened, the end surface 63 on the other axial side of the annular member 50 is pressed by the end surface 62 on the one axial side of the outer ring 4 to be knuckle 60. Is moved from the wheel side to the vehicle body side. In this manner, the end surface 63 on the other side in the axial direction of the annular member 50 is in contact with the end surface 62 on the one side in the axial direction of the outer ring 4.

  2, with the knuckle 60 in contact with the vehicle body mounting flange 43 of the outer ring 4, one end face 62 in the axial direction of the outer ring 4 is opposed to the end face 62 in the axial direction. The axial distance from the end face 68 of the knuckle 60 is set to L3 [cm], and referring to FIG. 4, the axial dimension of the annular member 50 is set to L4 [cm]. In this embodiment, L4 ≦ L3 is satisfied, and the presence of the annular member 50 does not affect the tightening of the vehicle body mounting flange 43 and the knuckle 60 by the bolt 61.

  According to the hub unit of the above embodiment, the annular member 50 made of a material having a higher ionization tendency than the steel material that is the material of the outer ring 4 is configured to contact the end surface 62 in the axial direction of the outer ring 4. Also, the annular member 50 can be preferentially corroded, and corrosion of the outer ring 4 can be suppressed. Therefore, even if the knuckle 60 which is flooded with highly corrosive mud salt water and attaches the outer ring 4 to the vehicle body is an inexpensive steel knuckle, corrosion of the expensive outer ring 4 can be suppressed. More specifically, in the present invention, since the annular member 50 which is a separate member from the inner rings 2 and 3 and the outer ring 4 is arranged, it is possible to secure a wide corrosion area in the axial direction, The anticorrosion performance can be remarkably enhanced, and corrosion of the outer ring can be suppressed over a long period of time.

  Further, according to the hub unit of the above embodiment, the inner diameter of the annular member 50 is larger than the inner diameter of the end surface 62 on one side in the axial direction of the outer ring 4, so When press-fitting the seal member 42, the annular member 50 does not get in the way, and the seal member 42 can be smoothly fixed to the inner peripheral surface of the outer ring 4.

  Further, according to the hub unit of the above embodiment, the inner diameter of the annular member 50 is larger than the inner diameter of the end surface 62 on one side of the outer ring 4 in the axial direction. The movement of foreign matter (dust and muddy water) to the side can be suppressed. Accordingly, it is possible to suppress biting of foreign matter in the seal member 42 attached to the inner peripheral side of the outer ring 4 and to suppress rusting of the pulsar ring 40 of the rotational speed detection device 7.

  If the inner diameter of the annular member is smaller than the inner diameter of one end surface of the outer race member in the axial direction, the annular member is in contact with the outer race member, so that the outer race from the inner circumference surface of the foreign member annular member. The movement of the member by the centrifugal force toward the inner peripheral side makes it easy for foreign matter in the seal member to be caught and pulsar ring rusting to occur.

  Further, according to the hub unit of the above embodiment, the annular member 50 has the plating layer 91 that can suppress the corrosion of the end surface 62 of the outer ring 4 and has a corrosion-inhibiting effect in contact with the end surface 62 of the outer ring 4. Therefore, the crevice corrosion between the contact surface of the annular member 50 and the outer ring 4 can be suppressed, and the outer ring 4 does not get rusted by rust and further suppresses the corrosion of the outer ring 4. it can.

  In the hub unit of the above embodiment, the material of the main body 90 of the annular member 50 is aluminum that has a higher ionization tendency than the carbon steel that is the material of the outer ring 4, but in this invention, the outer ring is made of carbon steel or the like. In the case of a steel material, the material of the main body of the annular member may be zinc or magnesium, and any material may be used as long as it is a metal material other than aluminum that has a higher ionization tendency than the steel material.

  In the hub unit of the above embodiment, the annular member 50 is composed of the main body 90 and the plated layer 91. However, in the present invention, the annular member is composed of only the main body and does not have a plated layer. May be.

  In the hub unit of the above embodiment, the plated layer 91 of the annular member is formed of a zinc-nickel alloy capable of suppressing the corrosion of the end surface 62 on the one side in the axial direction of the outer ring 4. The plating layer may be formed of zinc, zinc manganese alloy, zinc iron alloy, zinc cobalt alloy, zinc molybdenum alloy, or the like.

  Further, the hub unit of the above embodiment is configured to press-fit two inner rings 2 and 3 as inner race members into the inner shaft 1, but the hub unit of the present invention has only one inner ring on the inner shaft. A configuration may be adopted in which one outer raceway surface is formed on each of the inner shaft and the inner ring, and each of the inner shaft and the inner ring may be an inner race member. Further, the hub unit of the present invention may have a configuration in which two raceway surfaces are formed on the inner shaft as the only inner raceway member without an inner ring.

  In the hub unit of the above embodiment, the annular member 50 has a C-shape. However, in this invention, the annular body is a member having a closed curved surface that defines a through hole, and is notched. May not be included. This is because the hub unit does not necessarily have to be attached with a rotation speed detection sensor, and it is not necessary to form a drain hole that requires a notch.

  In the hub unit of the above embodiment, the rolling elements are balls 5 and 6. However, in this invention, the rolling elements may be tapered rollers arranged in two rows, and the rolling elements are A cylindrical roller may be used, and the rolling element may be composed of two or more of a tapered roller, a cylindrical roller, and a ball.

  In the above embodiment, the hub unit is fixed to the cast iron knuckle 60. However, the hub unit of the present invention is fixed to a knuckle made of a material other than cast iron, such as an aluminum knuckle. Of course, it can be done.

2 First inner ring 3 Second inner ring 4 Outer ring 5 First ball 6 Second ball 15 Wheel mounting flange 21 First inner ring raceway groove 22 Second inner ring raceway groove 30 Outer ring first raceway groove 31 Outer ring first Two raceway grooves 43 Car body mounting flange 50 Annular member 60 Knuckle 62 End surface on one side in the axial direction of the outer ring 63 End surface on the other side in the axial direction of the annular member 90 Body 91 Plating layer

Claims (3)

A steel outer race member having a vehicle body mounting flange for attaching a knuckle and an inner circumferential raceway surface;
An inner race member having an outer raceway surface;
A rolling element disposed between the inner circumferential raceway surface of the outer raceway member and the outer circumferential raceway surface of the inner raceway member;
An annulus made of a material that is fitted to the inner peripheral surface of the knuckle, contacts the end surface on one axial side of the outer race member, and has a higher ionization tendency than the ionization tendency of the material of the outer race member A hub unit comprising: a member. The hub unit according to claim 1,
The hub unit, wherein an inner diameter of the annular member is smaller than an inner diameter of one end face in the axial direction of the outer race member. The hub unit according to claim 1 or 2,
The said annular member can suppress the corrosion of the said end surface of the said outer track member, and has a corrosion suppression layer contact | abutted to the said end surface of the said outer track member, The hub unit characterized by the above-mentioned.

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