JP7523336B2 - Steering shaft - Google Patents

Description

This disclosure relates to a steering shaft.

A vehicle is provided with a steering device as a device for transmitting the operation of the steering wheel by the operator (driver) to the wheels (see, for example, Patent Document 1). The steering device includes a steering shaft that transmits rotational torque. The steering shaft includes an inner shaft having a first tooth portion on its outer circumference, an outer shaft having a second tooth portion on its inner circumference, and a resin layer provided on the outer circumferential surface of the first tooth portion. By providing the resin layer, the sliding resistance between the first tooth portion and the second tooth portion is reduced. Note that grease may be applied to the outer circumferential surface of the resin layer to further reduce the sliding resistance.

JP 2017-145945 A

The resin layer is susceptible to thermal deformation at high temperatures. If the steering shaft described in Patent Document 1 is exposed to a high-temperature environment, the resin layer provided on the first tooth portion may be thermally deformed. Furthermore, in recent years, steering shafts have been placed in higher temperature environments due to radiant heat from turbochargers, for example. This may cause the resin layer to thermally deform, increasing the sliding resistance between the first tooth portion and the second tooth portion.

The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a steering shaft that can further reduce the sliding resistance between the teeth of the inner shaft and the teeth of the outer shaft.

To achieve the above object, a steering shaft according to one embodiment of the present disclosure includes an inner shaft having a first tooth portion on its outer circumferential surface and extending in an axial direction along a central axis, an outer shaft having a second tooth portion on its inner circumferential surface and disposed on the outer circumferential side of the first tooth portion, a resin layer disposed between the first tooth portion and the second tooth portion, and an annular hole cover provided on the outer circumferential side of the outer shaft, the hole cover having a plurality of bellows disposed on either side of a hollow portion, and disposed so as to overlap the resin layer when viewed from the radial direction.

The hole cover includes a plurality of bellows arranged on either side of the hollow portion. Since air is stored in the hollow portion, the hole cover has a heat insulating effect. Therefore, compared to the steering shaft described in Patent Document 1, when heat is applied to the steering shaft, the hole cover can suppress the temperature rise of the resin layer. Therefore, in the present disclosure, the thermal deformation of the resin layer is suppressed, and it is possible to further reduce the sliding resistance between the first tooth portion of the inner shaft and the second tooth portion of the outer shaft. Note that, when the inner shaft and the outer shaft are made of metal, when heat is applied to the steering shaft, the resin layer thermally expands more than the inner shaft and the outer shaft, and the sliding resistance between the resin layer and the first tooth portion or the second tooth portion increases. Therefore, by suppressing the temperature rise of the resin layer with the hole cover, the sliding resistance between the resin layer and the first tooth portion or the second tooth portion can be further reduced.

A desirable aspect of the steering shaft is that it comprises a heat insulating material provided on the outer periphery of the outer shaft, and a heat shielding material provided on the outer periphery of the heat insulating material and having a higher heat reflectance than the heat insulating material, the hole cover is provided on the outer periphery of the heat shielding material, and the heat shielding material and the heat insulating material overlap with the resin layer when viewed from the radial direction.

In this way, by arranging the heat shield and heat insulating material radially outside the resin layer in addition to the hole cover, thermal deformation of the resin layer is further suppressed, and it is possible to further reduce the sliding resistance between the first tooth portion of the inner shaft and the second tooth portion of the outer shaft.

In a preferred embodiment of the steering shaft, the heat insulating material and the heat shielding material are fixed to the outer circumferential surface of the outer shaft with an adhesive. This increases the fixing strength of the heat insulating material and the heat shielding material to the outer shaft.

In a preferred embodiment of the steering shaft, the heat shield is a stainless steel plate. This makes it possible to further improve the corrosion resistance of the heat shield.

In a preferred embodiment of the steering shaft, the heat shield is a plated steel sheet. This makes it possible to further improve the corrosion resistance of the heat shield.

In a preferred embodiment of the steering shaft, the heat shield is an aluminum plate having an anodized coating on its surface. This can further improve the corrosion resistance of the heat shield. In addition, when grease is applied to the surface of the aluminum plate having an anodized coating, the grease is retained and supplied by being accumulated in the pores formed in the anodized coating (alumite layer), so that the sliding resistance between the resin layer and the first tooth portion or the second tooth portion can be further reduced. Furthermore, the thermal conductivity of the aluminum plate having an anodized coating is significantly lower than that of an aluminum plate without a coating, so that the thermal expansion of the resin layer can be further suppressed, and the sliding resistance between the resin layer and the first tooth portion or the second tooth portion can be further reduced.

This disclosure makes it possible to provide a steering shaft that can further reduce the sliding resistance between the teeth of the inner shaft and the teeth of the outer shaft.

FIG. 1 is a schematic diagram showing an outline of a steering device according to a first embodiment. FIG. 2 is a perspective view showing an outline of the steering device according to the first embodiment. FIG. 3 is a perspective view showing the lower shaft, the hole cover, and the universal joint of FIG. 2. FIG. FIG. 4 is a side view of FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a side view showing an outline of a steering device according to the second embodiment. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG.

A detailed description of the form (embodiment) for carrying out the invention will be given with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the components described below can be combined as appropriate. In the drawings, FR indicates the front side of the vehicle body, and RR indicates the rear side of the vehicle body.

[First embodiment]
Fig. 1 is a schematic diagram showing an outline of a steering device according to a first embodiment. Fig. 2 is a perspective view showing an outline of the steering device according to the first embodiment.

As shown in Figures 1 and 2, the steering device 80 includes, in the order of transmission of force applied by the operator, a steering wheel 81, an upper shaft 82, a steering force assist mechanism 83, a universal joint 84, a lower shaft (steering shaft) 1, and a universal joint 86, which are joined to a pinion shaft 87. The steering device 80 also includes an ECU (Electronic Control Unit) 90 and a torque sensor 94. A vehicle speed sensor 95 is provided on the vehicle body and outputs a vehicle speed signal V to the ECU 90 via CAN (Controller Area Network) communication.

The upper shaft 82 includes an input shaft 82a and an output shaft 82b. One end of the input shaft 82a is connected to the steering wheel 81, and the other end of the input shaft 82a is connected to the output shaft 82b. One end of the output shaft 82b is connected to the input shaft 82a, and the other end of the output shaft 82b is connected to a universal joint 84. In this embodiment, the input shaft 82a and the output shaft 82b are made of general steel materials such as carbon steel for machine structural use (SC material (Carbon Steel for Machine Structural Use)) or carbon steel tubes for machine structural purposes (so-called STKM material (Carbon Steel Tubes for Machine Structural Purposes)).

The lower shaft (steering shaft) 1 is a member that is connected to the output shaft 82b via a universal joint 84. A hole cover 7 is attached to the outer periphery of the lower shaft 1. One end of the lower shaft 1 is connected to the universal joint 84, and the other end is connected to a universal joint 86. One end of the pinion shaft 87 is connected to the universal joint 86, and the other end of the pinion shaft 87 is connected to a steering gear 88.

The steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to the pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into linear motion by the rack 88b. The rack 88b is connected to a tie rod 89. In other words, the steering device 80 is of the rack-and-pinion type.

The steering force assist mechanism 83 includes a reduction gear 92 and an electric motor 93. The electric motor 93 is, for example, a brushless motor, but may also be a motor including a brush (slider) and a commutator (commutator). The reduction gear 92 is, for example, a worm reduction gear. The torque generated by the electric motor 93 is transmitted to the worm wheel via the worm inside the reduction gear 92, causing the worm wheel to rotate. The reduction gear 92 increases the torque generated by the electric motor 93 by means of the worm and the worm wheel. The reduction gear 92 then applies an auxiliary steering torque to the output shaft 82b. In other words, the steering device 80 is of a column assist type.

The torque sensor 94 detects the steering force of the operator transmitted to the input shaft 82a via the steering wheel 81 as a steering torque. The vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90.

The ECU 90 controls the operation of the electric motor 93. The ECU 90 also acquires signals from the torque sensor 94 and the vehicle speed sensor 95. That is, the ECU 90 acquires the steering torque T from the torque sensor 94 and the vehicle speed signal V from the vehicle speed sensor 95. The ECU 90 is supplied with power from a power supply device (e.g., an on-board battery) 99 when the ignition switch 98 is on. The ECU 90 calculates an auxiliary steering command value of the assist command based on the steering torque T and the vehicle speed signal V. The ECU 90 then adjusts the power value X to be supplied to the electric motor 93 based on the calculated auxiliary steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93 as operation information Y.

The steering force of the operator (driver) input to the steering wheel 81 is transmitted to the reduction gear 92 of the steering force assist mechanism 83 via the input shaft 82a. At this time, the ECU 90 obtains the steering torque T input to the input shaft 82a from the torque sensor 94, and obtains the vehicle speed signal V from the vehicle speed sensor 95. The ECU 90 then controls the operation of the electric motor 93. The auxiliary steering torque generated by the electric motor 93 is transmitted to the reduction gear 92.

The steering torque (including auxiliary steering torque) output through the output shaft 82b is transmitted to the lower shaft (steering shaft) 1 through a universal joint 84, and is further transmitted to the pinion shaft 87 through a universal joint 86. The steering force transmitted to the pinion shaft 87 is transmitted to the tie rod 89 through a steering gear 88, displacing the wheels.

Figure 3 is a perspective view showing the lower shaft, hole cover, and universal joint of Figure 2. Figure 4 is a side view of Figure 3. Figure 5 is a cross-sectional view taken along line V-V of Figure 4.

As shown in FIG. 3, the lower shaft (steering shaft) 1 includes an inner shaft 2, an outer shaft 3, and a resin layer 4 (see FIG. 5). The inner shaft 2 and the outer shaft 3 extend along the axial direction of the central axis Ax. One axial side of the lower shaft (steering shaft) 1 is the rear side of the vehicle body (inner side), and the other axial side is the front side of the vehicle body (outer side).

The universal joint 86 is connected to the front end (vehicle exterior) of the outer shaft 3. Specifically, a through hole is provided at the end of the universal joint 86. The end of the outer shaft 3 also includes a yoke portion 31. The yoke portion 31 branches into two branches, and a through hole is provided at the branched portion. The spider 311 is inserted and fitted into the through hole at the end of the universal joint 84 and the through hole in the yoke portion 31, thereby connecting the universal joint 86 to the outer shaft 3.

As shown in FIG. 5, the inner shaft 2 has a small diameter portion 23 and a large diameter portion 22. The inner shaft 2 can be made of a wide variety of metals, such as carbon steel. The inner shaft 2 is a cylindrical hollow member, and has a through hole 21 formed along the axial direction of the central axis Ax. The diameter of the small diameter portion 23 is smaller than the diameter of the large diameter portion 22. The inner shaft 2 has a first tooth portion 24 on the outer circumferential surface of the large diameter portion 22. The first tooth portion 24 is arranged at equal intervals along the circumferential direction on the outer circumferential surface of the large diameter portion 22. A resin layer 4 is provided on the outer circumferential surface of the first tooth portion 24. It is desirable that the resin layer 4 be used in a temperature environment of, for example, 80 degrees or less.

The outer shaft 3 has a small diameter section 32, an inclined section 34, and a large diameter section 33. The outer shaft 3 can be made of a wide variety of metals, such as carbon steel. The outer shaft 3 is a cylindrical hollow member that extends in the axial direction of the central axis Ax.

The small diameter portion 32 extends from the end 320 on the rear side (inside the vehicle) of the vehicle body to the end 321 on the front side. The inclined portion 34 extends from the end 321 to the end 341. The large diameter portion 33 extends from the end 341 to the yoke portion 31. The inner diameter of the small diameter portion 32 is smaller than the inner diameter of the large diameter portion 33. The inner diameter of the inclined portion 34 increases from the end 321 to the end 341.

A plurality of second teeth 35 are arranged at equal intervals along the circumferential direction on the inner peripheral surface of the small diameter portion 32. The second teeth 35 are arranged on the outer peripheral side of the first teeth 24. Note that the resin layer 4 is provided on the outer peripheral surface of the first teeth 24, but may be provided on the inner peripheral side of the second teeth 35.

A lip component 9 is provided at the end 320 of the small diameter portion 32 of the outer shaft 3. The lip component 9 is annular about the central axis Ax. The lip component 9 includes a lip portion 91, a radial portion 96, and a bent portion 97. Specifically, the lip component 9 is a dust seal. The bent portion 97 extends in the axial and circumferential directions. The radial portion 96 extends from the axial end of the bent portion 97 toward the radially inward direction (toward the inner circumferential side). The lip portion 91 is in contact with the outer peripheral surface of the small diameter portion 23 of the inner shaft 2. As a result, the lip portion 91 seals the gap between the inner shaft 2 and the outer shaft 3.

A ring-shaped hole cover 7 is provided on the outer periphery of the small diameter portion 32 of the outer shaft 3. Specifically, the hole cover 7 is provided at a position where, when viewed from the radial direction, the axial position overlaps with the resin layer 4 on the outer periphery of the first tooth portion 24. In other words, the position of the hole cover 7 and the position of the resin layer 4 on the outer periphery of the first tooth portion 24 overlap in terms of axial position when viewed from the radial direction. Specifically, when viewed from the radial direction, the range along the axial direction from the first seal member 73 to the second seal member 74 described later overlaps with the resin layer 4. Here, "overlap" and "overlapping" mean that at least a portion of the overlap is sufficient.

The hole cover 7 includes a bellows 71, a bush 72, a first seal member 73, a second seal member 74, and a bracket 75. Two bellows 71 are provided at an interval in the axial direction. A hollow portion 70 is provided between the two bellows 71. In other words, the two bellows 71 are arranged with the hollow portion 70 sandwiched between them. Bellows 71 Note that three or more bellows 71 may be provided. The bush 72 is, for example, a circular resin part, and is arranged on the outer periphery of the small diameter portion 32. The radial inner end of the bellows 71 is fixed to the bush 72 via the bracket 75. The first seal member 73 and the second seal member 74 are flexible. The first seal member 73 is fixed to the axial end of the bush 72. A lip portion 731 is provided at the tip of the first seal member 73. The lip portion 731 contacts the outer peripheral surface of the large diameter portion 33. The second seal member 74 is fixed to the bracket 75. A lip portion 741 is provided at the tip of the second seal member 74. The lip portion 741 contacts the outer peripheral surface of the small diameter portion 32.

The steering shaft 1 of the first embodiment having the above configuration includes an inner shaft 2 having a first tooth portion 24 on its outer circumferential surface and extending in the axial direction along the central axis Ax, an outer shaft 3 having a second tooth portion 35 on its inner circumferential surface and disposed on the outer circumferential side of the first tooth portion 24, a resin layer 4 disposed between the first tooth portion 24 and the second tooth portion, and an annular hole cover 7 provided on the outer circumferential side of the outer shaft 3, and the hole cover 7 includes two (or more) bellows 71 disposed on either side of a hollow portion 70, and overlaps with the resin layer 4 when viewed from the radial direction.

The hole cover 7 includes two bellows 71 arranged with a hollow portion 70 therebetween. Since air is stored in the hollow portion 70, the hole cover 7 has a heat insulating effect. Therefore, compared to the steering shaft described in Patent Document 1, when heat is applied to the steering shaft 1, the hole cover 7 can suppress the temperature rise of the resin layer 4. Therefore, in the first embodiment, the thermal deformation of the resin layer 4 is suppressed, and it is possible to further reduce the sliding resistance between the first tooth portion 24 of the inner shaft 2 and the second tooth portion 35 of the outer shaft 3. Since the inner shaft 2 and the outer shaft 3 are made of metal, when heat is applied to the steering shaft 1, the resin layer 4 thermally expands more than the inner shaft 2 and the outer shaft 3, and the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 becomes large. Therefore, by suppressing the temperature rise of the resin layer 4 with the hole cover 7, the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 can be further reduced.

[Second embodiment]
Next, a second embodiment will be described, but the same reference numerals will be used to designate parts having the same structure as those in the first embodiment, and description thereof will be omitted. Fig. 6 is a side view showing an outline of a steering device according to the second embodiment. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6.

The steering shaft 1A according to the second embodiment differs from the steering shaft 1 according to the first embodiment in that it is provided with a heat insulating material 5 and a heat shielding material 6. This will be explained in detail below.

The outer shaft 3 includes a small diameter portion 32, an inclined portion 34, and a large diameter portion 33. The insulating material 5 and the heat shielding material 6 are provided on the outer periphery of the small diameter portion 32. The insulating material 5 includes an inner periphery 51, an outer periphery 52, an axial end 53, and an axial end 54. The insulating material 5 may be, for example, glass wool or cellulose fiber. The insulating material 5 has a cylindrical shape extending in the circumferential direction around the central axis Ax. In the second embodiment, the inner periphery 51 of the insulating material 5 is in contact with the outer periphery of the small diameter portion 32, but there may be a gap between the inner periphery 51 of the insulating material 5 and the outer periphery of the small diameter portion 32. The insulating material 5 is provided on the outer periphery of the outer shaft 3 at a position overlapping with the resin layer 4 when viewed from the radial direction.

The heat shielding material 6 is provided on the outer periphery of the heat insulating material 5. In other words, the heat shielding material 6 overlaps with the resin layer 4 when viewed from the radial direction. The heat shielding material 6 has an inner peripheral surface, an outer peripheral surface, an axial end 61, and an axial end 62. For example, various metal plates can be used for the heat shielding material 6. Specifically, for example, a stainless steel plate, a plated steel plate, or an aluminum plate with an anodized film on the surface (i.e., an aluminum plate with an anodized surface) can be used for the heat shielding material 6. Note that hard anodized aluminum is preferable as the anodized aluminum. The heat reflectance of the heat shielding material 6 is higher than that of the heat insulating material 5. The axial end 53 of the heat insulating material 5 and the axial end 61 of the heat insulating material 6 are arranged at the same position in the axial direction, and the axial end 54 of the heat insulating material 5 and the axial end 62 of the heat insulating material 6 are arranged at the same position in the axial direction. In this way, the heat insulating material 5 and the heat shielding material 6 are formed into a two-layer structure in the radial direction.

A lip component 9 is provided at the end 320 of the small diameter portion 32 of the outer shaft 3. The axial end 53 of the heat insulating material 5 and the axial end 61 of the heat shielding material 6 are disposed forward of the end 320 of the outer shaft 3 on the vehicle body. An adhesive 110 is provided between the axial ends 53, 61 and the bent portion 97 of the lip component 9. The heat insulating material 5 and the heat shielding material 6 are therefore fixed to the outer peripheral surface of the outer shaft 3 by the adhesive 110.

Furthermore, the axial end 54 of the heat insulating material 5 and the axial end 62 of the heat shielding material 6 are positioned rearward in the vehicle body relative to the end 321 of the outer shaft 3. An adhesive 100 is provided between the axial ends 54, 62 and the outer peripheral surface of the outer shaft 3. Thus, the heat insulating material 5 and the heat shielding material 6 are fixed to the outer peripheral surface of the outer shaft 3 by the adhesive 100. Note that the adhesives 100, 110 can be, for example, thermosetting adhesives. The thermosetting adhesive is an adhesive whose main component is a thermosetting resin.

The procedure for assembling the heat insulating material 5 and the heat shielding material 6 will be briefly described. First, the heat insulating material 5 and the heat shielding material 6 are inserted into the small diameter portion 32 of the outer shaft 3 from the rear side in FIG. 7. At this time, since the bent portion 97 of the lip member 9 extends forward, the insertion of the heat insulating material 5 and the heat shielding material 6 is not hindered. Next, the heat insulating material 5 and the heat shielding material 6 are moved toward the front side. Then, adhesive 110 is applied between the axial ends 53, 61 and the bent portion 97 of the lip member 9. Also, adhesive 190 is applied between the axial ends 54, 62 and the outer peripheral surface of the outer shaft 3 over the entire circumference in the circumferential direction. As a result, the heat insulating material 5 and the heat shielding material 6 are fixed to the outer peripheral surface of the outer shaft 3 by the adhesives 100, 110. The adhesive 110 has a sealing function for sealing the gap between the heat insulating material 5 and the heat shielding material 6 and the outer peripheral surface of the outer shaft 3 to suppress the intrusion of water, etc. If a large amount of water seeps in through the gaps between the insulation material 5 and heat shielding material 6 and the outer circumferential surface of the outer shaft 3, the volume of the insulation material 5 will decrease, forming gaps between the insulation material 5 and the outer circumferential surface of the outer shaft 3, which may cause the hole cover 7 and the insulation material 5 and heat shielding material 6 to rotate together.

The steering shaft 1A of the second embodiment having the above configuration includes a heat insulating material 5 provided on the outer periphery of the outer shaft 3, and a heat shielding material 6 provided on the outer periphery of the heat insulating material 5 and having a higher thermal reflectance than the heat insulating material 5. The hole cover 7 is provided on the outer periphery of the heat shielding material 6, and the heat shielding material 6 and the heat insulating material 5 overlap with the resin layer 4 when viewed from the radial direction.

In the second embodiment, in addition to the hole cover 7, the heat shielding material 6 and the heat insulating material 5 are arranged radially outside the resin layer 4. Therefore, in the second embodiment, the thermal deformation of the resin layer 4 is further suppressed, and it is possible to further reduce the sliding resistance between the first tooth portion 24 of the inner shaft 2 and the second tooth portion 35 of the outer shaft 3. Since the inner shaft 2 and the outer shaft 3 are made of metal, when heat is applied to the steering shaft 1, the resin layer 4 thermally expands more than the inner shaft 2 and the outer shaft 3, and the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 becomes larger. Therefore, by further suppressing the rise in temperature of the resin layer 4 by the hole cover 7, the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 can be further reduced.

The heat insulating material 5 and the heat shielding material 6 are fixed to the outer circumferential surface of the outer shaft 3 with adhesives 100 and 110. This increases the fixing strength of the heat insulating material 5 and the heat shielding material 6 to the outer shaft 3.

When a stainless steel plate, a plated steel plate, or an aluminum plate with an anodized film on the surface is used as the heat shield 6, the corrosion resistance of the heat shield 6 can be further improved. In particular, when grease is applied to the surface of an aluminum plate with an anodized film (alumite layer), the grease is retained and supplied by being accumulated in the pores (air holes) formed in the anodized film, so that the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 can be further reduced. Furthermore, since the thermal conductivity of an aluminum plate with an anodized film is significantly lower than that of an aluminum plate without a film, the thermal expansion of the resin layer 4 can be further suppressed, and the sliding resistance between the resin layer 4 and the first tooth portion 24 or the second tooth portion 35 can be further reduced.

When the hole cover 7 is attached to the vehicle body, it may be provided on the rear side of the resin layer 4 on the vehicle body. In other words, the resin layer 4 may be provided on the front side of the hole cover 7 on the vehicle body. This will be specifically explained below. First, the hole cover 7 is attached to a dash panel, which is a part of the vehicle body. The dash panel is a panel that separates the inside of the vehicle from the outside. Therefore, the front side of the vehicle body from the dash panel is the engine room, and the rear side of the vehicle body from the dash panel is the passenger compartment. The engine room may be hotter than the passenger compartment. Therefore, in order to protect the resin layer 4 from heat when it is placed in the engine room, the heat insulating material 5 and the heat shielding material 6 are placed radially outside the resin layer 4.

1, 1A Lower shaft (steering shaft)
2 Inner shaft 21 Through hole 22 Large diameter portion 23 Small diameter portion 3 Outer shaft 31 Yoke portion 32 Small diameter portion 321 End 33 Large diameter portion 34 Inclined portion 341 End 4 Resin layer 5 Heat insulating material 51 Inner peripheral surface 52 Outer peripheral surface 53, 54 Axial end 6 Heat shield material 61, 62 Axial end 7 Hole cover 70 Hollow portion 71 Bellows 72 Bush 73 First seal member 731, 741 Lip portion 74 Second seal member 75 Bracket 80 Steering device 81 Steering wheel 82 Upper shaft 82a Input shaft 82b Output shaft 83 Steering force assist mechanism 84, 86 Universal joint 87 Pinion shaft 88 Steering gear 88a Pinion 88b Rack 89 Tie rod 90 ECU
92 Reduction gear 93 Electric motor 94 Torque sensor 95 Vehicle speed sensor 98 Ignition switch 99 Power supply device 9 Lip member 91 Lip portion 96 Radial portion 97 Bent portion

Claims (6)

an inner shaft having a first tooth portion on an outer circumferential surface thereof and extending in an axial direction along a central axis;
an outer shaft having a second tooth portion on an inner peripheral surface thereof and disposed on an outer peripheral side of the first tooth portion;
a resin layer disposed between the first tooth portion and the second tooth portion;
an annular hole cover provided on an outer circumferential side of the outer shaft,
The hole cover includes a plurality of bellows disposed to sandwich a hollow portion, and is disposed so as to overlap the resin layer when viewed from a radial direction. A heat insulating material provided on an outer circumferential side of the outer shaft;
A heat shielding material is provided on the outer periphery of the heat insulating material and has a heat reflectance higher than the heat insulating material,
The hole cover is provided on an outer circumferential side of the heat shielding material,
The steering shaft according to claim 1 , wherein the heat shielding material and the heat insulating material overlap with the resin layer when viewed in a radial direction. The heat insulating material and the heat shielding material are fixed to the outer circumferential surface of the outer shaft with an adhesive.
3. A steering shaft according to claim 2. The heat shield is a stainless steel plate.
4. A steering shaft according to claim 2 or 3. The heat shielding material is a plated steel sheet.
4. A steering shaft according to claim 2 or 3. The heat shield is an aluminum plate having an anodized coating on its surface.
4. A steering shaft according to claim 2 or 3.

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