Steering device

Abstract

Provided is a steering device comprising a seal structure having higher seal performance. In the sealing structure, an annular seal member is disposed between a first member and a second member. The first member is provided with: a base part; a support part that is situated to the outer side of the base part; a first flange that projects farther to one side in a first direction than the support part and that surrounds the base part; and a protruding part that is provided on the intersection portion of the outer peripheral surface of the first flange and the support part and that projects farther to the outer side than the first flange. The second member has a second flange disposed to the outer side of the first flange.

Description

Steering device

[0001] The present disclosure relates to a steering device.

[0002] Patent Document 1 discloses a steering device including a shaft extending in the axial direction of a central axis and a gearbox connected to the shaft. The gearbox includes a tube housing having a first flange, a gear housing having a second flange facing the first flange, and an annular seal member disposed between the first flange and the second flange. Both the first flange and the second flange extend in the circumferential direction around the central axis. The second flange is located on the outer peripheral side of the first flange. A concave groove recessed toward the inner peripheral side is provided on the outer periphery of the first flange. The inner periphery of the second flange has a straight portion and a tapered portion. The straight portion is a cylindrical surface adjacent to one axial side of the tapered portion and extending in the circumferential direction around the central axis. The tapered portion has a diameter that increases as it goes to the other axial side.

[0003] Japanese Patent Application Laid-Open No. 2021-169251

[0004] In Patent Document 1, the inner peripheral portion of the seal member is pressed against the concave groove of the first flange of the tube housing, and the outer peripheral portion of the seal member is pressed against the tapered portion of the second flange of the gear housing. The second flange is located on the outer peripheral side with respect to the first flange. Therefore, a force is applied from the seal member to the tapered portion in the direction in which the second flange expands toward the outer peripheral side. As a result, there is a possibility that the sealing performance between the first flange and the second flange may deteriorate.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a steering device having a seal structure with higher seal performance.

[0006] To achieve the above objective, a steering device according to one aspect of the present disclosure comprises: a base; a support portion located outside the base; a first member having a first flange that protrudes from the support portion to one side in the first direction and surrounds the base; and a convex portion provided at the intersection of the outer peripheral surface of the first flange and the support portion and protruding outward from the first flange; a second member having a second flange disposed outside the first flange and fixed to the first member; and an annular sealing member disposed between the first member and the second member, wherein the opposing surface of the second flange facing the first flange has a straight portion extending in the first direction and a tapered portion provided adjacent to the other side in the first direction relative to the straight portion and whose diameter increases as it goes toward the other side in the first direction; and the first surface, which is the surface of the convex portion on one side in the first direction, is located on one side in the first direction relative to the second surface, which is the surface of the support portion on one side in the first direction.

[0007] As mentioned above, in the gearbox according to Patent Document 1, the second flange is located on the outer circumference side of the first flange. The inner circumference of the second flange has a straight section and a tapered section whose diameter increases towards the other side in the axial direction. The outer circumference portion of the sealing member is pressed against the tapered section of the second flange. Therefore, a force is applied from the sealing member to the tapered section in a direction that causes the second flange, which is located on the outer circumference side of the first flange, to expand outward. This may reduce the sealing performance between the first flange and the second flange.

[0008] In contrast, in this disclosure, a protrusion projecting to one side in the first direction is provided at the intersection of the outer circumferential surface of the first flange and the support portion. The first surface of the protrusion is located on one side in the first direction relative to the second surface of the support portion. Therefore, the sealing member abuts against the outer circumferential surface of the first flange, the first surface of the protrusion, and the inner circumferential surface of the second flange. Thus, in this disclosure, compared to Patent Document 1, a protrusion projecting to one side in the first direction is provided, and the first surface of the protrusion 23 is located on one side in the first direction relative to the second surface of the support portion. Therefore, since the sealing member according to this disclosure is located further to one side in the first direction than the sealing member according to Patent Document 1, the sealing member is more likely to abut against the straight portion and less likely to abut against the tapered portion. As a result, it is less likely for force to be applied from the sealing member to the tapered portion, and consequently, a decrease in the sealing performance between the first flange and the second flange is suppressed.

[0009] In a preferred embodiment, the first member is made of metal, and the second member is made of resin. Even if the second member is made of resin, sufficient sealing performance can be maintained.

[0010] To achieve the above objective, a steering device according to another aspect of the present disclosure comprises: a pinion shaft extending from inside the vehicle to outside the vehicle; a gearbox located outside the vehicle and connected to the pinion shaft; an annular cover covering the outer circumference of the pinion shaft; and an annular sealing member located between the gearbox and the cover and provided on the outer circumference side of the pinion shaft, wherein the axial direction of the central axis of the pinion shaft is defined as a first direction, the inside of the vehicle is one side of the first direction, and the outside of the vehicle is the other side of the first direction, and the gearbox comprises: a first flange located on the outer circumference side of the pinion shaft and protruding to one side of the first direction; and the other side of the first direction of the first flange The cover has a support portion extending radially outward, and a convex portion provided at the intersection of the outer circumferential surface of the first flange and the support portion and projecting toward one side in the first direction. The cover has a second flange positioned on the outer circumferential side of the first flange, and the sealing member is positioned between the first flange and the second flange. The inner circumferential surface of the second flange has a straight portion extending in the first direction, and a tapered portion provided adjacent to the other side of the straight portion in the first direction and whose diameter increases toward the other side in the first direction. The first surface of the convex portion, which is the surface on one side in the first direction, is located toward one side in the first direction relative to the second surface, which is the surface on one side in the first direction of the support portion.

[0011] In other embodiments of this disclosure, the force applied from the sealing member to the tapered portion becomes less likely, and consequently, a decrease in the sealing performance between the first flange and the second flange is suppressed.

[0012] In a preferred embodiment, the pinion shaft is connected to the steering wheel and penetrates the vehicle body panel, and the cover is positioned between the vehicle body panel and the gearbox, with one side in the first direction facing the vehicle body panel relative to the gearbox and the other side in the first direction facing the gearbox relative to the vehicle body panel. This allows the sealing structure of the present disclosure to more reliably seal liquids, debris, and other contaminants entering through the through-hole in the vehicle body panel.

[0013] In a preferred embodiment, the first surface of the protrusion overlaps with the straight portion of the second flange when viewed from the radial direction.

[0014] As a result, when the sealing member is placed on the first surface of the convex portion, the sealing member is more likely to come into contact with the straight portion of the second flange and less likely to come into contact with the tapered portion. Therefore, a decrease in the sealing performance between the first flange and the second flange is suppressed.

[0015] In a preferred embodiment, the first surface of the protrusion overlaps with the tapered portion of the second flange when viewed from the radial direction.

[0016] As mentioned above, if the height of the protrusion is increased so that the first surface of the protrusion overlaps with the straight portion of the second flange when viewed from the radial direction, the protrusion is more likely to come into contact with the inner surface of the second flange due to dimensional variations during manufacturing. Therefore, the height of the protrusion was made lower to reduce contact with the inner surface of the second flange.

[0017] In a preferred embodiment, the third surface, which is the radially outer surface of the protrusion, is positioned opposite the tapered portion of the second flange, the first flange is positioned opposite the straight portion of the second flange, and the first distance, which is the maximum distance between the third surface and the tapered portion, is smaller than the second distance, which is the maximum distance between the outer circumferential surface of the first flange and the straight portion.

[0018] If the height of the protrusion is made lower so that the first surface of the protrusion overlaps with the tapered portion of the second flange when viewed radially, a portion of the elastically deformed sealing member can easily enter the gap between the third surface of the protrusion and the tapered portion of the second flange. If a large amount of sealing member enters the gap, the sealing performance between the first and second flanges decreases. Therefore, in order to reduce the width of the gap and thus reduce the amount of sealing member that enters the gap, the first distance was made smaller than the second distance.

[0019] In a preferred embodiment, in a cross-section of the pinion shaft including the central axis, the area centroid of the sealing member overlaps with the straight portion of the second flange when viewed from the radial direction.

[0020] As a result, the sealing member is more likely to come into contact with the straight portion and less likely to come into contact with the tapered portion, thus suppressing a decrease in the sealing performance between the first flange and the second flange.

[0021] This disclosure makes it possible to provide a steering device equipped with a seal structure having higher sealing performance.

[0022] Figure 1 is a schematic diagram of the steering device of the first embodiment. Figure 2 is an enlarged cross-sectional view of a part of Figure 1. Figure 3 is a schematic diagram of part A of Figure 2. Figure 4 is a schematic diagram showing the seal structure before the cover is attached to the gearbox. Figure 5 is a schematic diagram showing the seal structure after the cover is attached to the gearbox. Figure 6 is a schematic diagram showing a cross-section of the seal structure between the cover and the gearbox according to the second embodiment. Figure 7 is a schematic diagram showing the seal structure before the cover is attached to the gearbox. Figure 8 is a schematic diagram showing the seal structure after the cover is attached to the gearbox. Figure 9 is a schematic diagram showing the seal structure before the cover is attached to the gearbox in Reference Example 1. Figure 10 is a schematic diagram showing the seal structure after the cover is attached to the gearbox in Reference Example 1. Figure 11 is a schematic diagram showing the seal structure before the cover is attached to the gearbox in Reference Example 2. Figure 12 is a schematic diagram showing the seal structure after the cover is attached to the gearbox in Reference Example 2. Figure 13 is an enlarged view of portion A in Figure 2 according to the first embodiment. Figure 14 is an enlarged view corresponding to portion A in Figure 2 according to a comparative example. Figure 15 is a schematic diagram showing the seal structure after the cover according to the third embodiment has been attached to the gearbox.

[0023] The present disclosure will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the embodiments described below. Furthermore, the components in the embodiments below include those easily conceivable by those skilled in the art, those substantially identical, and those within the so-called equivalence range. Moreover, the components disclosed in the embodiments below can be combined as appropriate. In the drawings, FR indicates the front of the vehicle, RR indicates the rear of the vehicle, UPR indicates the upper side of the vehicle, LWR indicates the lower side of the vehicle, IN indicates the interior of the vehicle, and OUT indicates the exterior of the vehicle.

[0024] [First Embodiment] First, the first embodiment will be described. Figure 1 is a schematic diagram of the steering device of the first embodiment. Figure 2 is an enlarged cross-sectional view of a part of Figure 1. As shown in Figures 1 and 2, the steering device 80 includes a steering wheel 81, a steering shaft 82, an intermediate shaft 83, a pinion shaft 84, a cover 1, and a gearbox 2.

[0025] As shown in Figures 1 and 2, one end of the steering shaft 82 is connected to the steering wheel 81, and the other end is connected to the intermediate shaft 83 via a universal joint 85. The intermediate shaft 83 is connected to the pinion shaft 84 via a universal joint 86. The universal joints 85 and 86 are, for example, cardan joints. In this way, the pinion shaft 84 is connected to the steering wheel 81. The rotation of the steering wheel 81 is transmitted to the pinion shaft 84 via the steering shaft 82 and the intermediate shaft 83.

[0026] Furthermore, a dash panel 92 extending vertically is positioned on the FR side of the vehicle relative to the steering wheel 81, steering shaft 82, and intermediate shaft 83. A floor panel (body panel) 93 extending in the longitudinal direction of the vehicle is positioned on the LWR side of the vehicle relative to the steering wheel 81, steering shaft 82, and intermediate shaft 83. In this way, the dash panel 92 and floor panel 93 separate the interior (IN) from the exterior (OUT). A through hole 93a is provided in the floor panel 93. The pinion shaft 84 extends vertically and passes through the through hole 93a in the floor panel 93. That is, the pinion shaft 84 extends from the interior (IN) to the exterior (OUT) by passing through the through hole 93a in the floor panel 93, which is a body panel. A gasket 94 is provided on the lower surface of the area surrounding the through hole 93a in the floor panel 93, and the gasket 94 maintains airtightness around the through hole 93a. A cover 1 is positioned on the lower LWR side of the vehicle relative to the gasket 94. A gearbox 2 is positioned on the lower LWR side of the vehicle relative to the cover 1.

[0027] As shown in Figure 2, the cover 1 comprises a main body portion 11, an upper enlarged diameter portion 12, and a lower enlarged diameter portion 13. The upper enlarged diameter portion 12 is attached to the gasket 94. The lower enlarged diameter portion 13 is attached to the upper part of the gearbox 2. The main body portion 11 connects the upper enlarged diameter portion 12 and the lower enlarged diameter portion 13. The pinion shaft 84 extends in the axial direction of the central axis AX.

[0028] Here, the axial direction of the central axis AX is also referred to as the first direction, the side X1 which is one side in the axial direction is also referred to as one side of the first direction, and the other side X2 which is the other side in the axial direction is also referred to as the other side of the first direction. In other words, the side of the floor panel 93 relative to the gearbox 2 is referred to as one side of the first direction, and the side of the gearbox 2 relative to the floor panel 93 is referred to as the other side of the first direction.

[0029] As shown in Figure 2, the pinion shaft 84 includes a first shaft 841, a second shaft 842, and a torsion bar 843. The first shaft 841 and the second shaft 842 are connected via the torsion bar 843. Specifically, the X1-side end of the torsion bar 843 is fitted onto the first shaft 841, and the X2-side end of the torsion bar 843 is fitted onto the second shaft 842. The X1-side end 842a of the second shaft 842 is an annular flange. The X2-side end 841a of the first shaft 841 is inserted into the inner circumference of the annular flange of the end 842a of the second shaft 842. Therefore, when the first shaft 841 rotates relative to the second shaft 842, the torsion bar 843 undergoes elastic deformation in a twisted state. In other words, the torsion bar 843 transmits rotational torque between the first shaft 841 and the second shaft 842. The torque sensor 96 detects the rotational torque transmitted between the first shaft 841 and the second shaft 842 via the torsion bar 843. A sliding bearing 95 is provided between the first shaft 841 and the main body 11 of the cover 1, and the second shaft 842 is rotatably supported via a needle bearing 97.

[0030] The outer circumferences of the torque sensor 96, the end 841a of the first shaft 841, and the end 842a of the second shaft 842 are covered by the lower end enlarged diameter portion 13 of the cover 1. The gearbox 2 has a base portion 29 and a first flange 21 that protrudes from the base portion 29 toward the X1 side. The second shaft 842 is inserted into the hollow portion of the base portion 29. In this embodiment, the first flange 21 has an annular shape that extends along the axial direction of the central axis AX. A second flange 14 that protrudes toward the X2 side is provided at the X2 side end of the lower end enlarged diameter portion 13 of the cover 1. In this embodiment, the second flange 14 has an annular shape that extends along the axial direction of the central axis AX. The first flange 21 and the second flange 14 are sealed via a sealing member 100. The sealing member 100 is an annular member provided on the outer circumference of the pinion shaft 84. In this embodiment, it has the sealing structure 200 shown in part A of Figure 2. The second flange 14 is fixed to the gearbox 2, for example, via bolts (not shown). While the sealing member 100 can be an elastic body such as an O-ring, the sealing member 100 is not limited to an O-ring in this disclosure.

[0031] As shown in Figure 1, the gearbox 2 also has a reduction mechanism 87. The reduction mechanism 87 has a worm wheel 871 and a worm gear 872. The output shaft of the motor 91 is provided with the worm gear 872, which meshes with the worm wheel 871. The worm wheel 871 is attached to the pinion shaft 84, and the pinion gear 88 is attached to the lower end of the pinion shaft 84. Therefore, when the motor 91 is driven, the worm gear 872 rotates, and the rotation of the worm gear 872 causes the worm wheel 871 and the pinion gear 88 to rotate. Since the pinion gear 88 meshes with the rack teeth (not shown) on the rack shaft 89, when the pinion gear 88 rotates, the rack shaft 89 moves in the left-right direction of the vehicle. As described above, the gearbox 2 is located outside the vehicle (OUT) and connected to the pinion shaft 84. Furthermore, the cover 1 is an annular member positioned between the floor panel (body panel) 93 and the gearbox 2, and covering the outer circumference of the end 841a of the first shaft 841 and the end 842a of the second shaft 842 in the pinion shaft 84.

[0032] Figure 3 is a schematic diagram of part A in Figure 2. More specifically, Figure 3 is a schematic diagram showing a cross-section of the seal structure 200 between the cover 1 and the gearbox 2 according to the first embodiment. The seal structure 200 according to the first embodiment will be described below with reference to Figure 3.

[0033] As shown in Figure 3, the gearbox 2 comprises a base 29, a first flange 21, a support portion 22, and a protrusion 23. The support portion 22 is located outside the base 29. The base 29 has a reference surface 291 on the X1 side. The support portion 22 has a second surface 25 on the X1 side. As shown in Figure 2, the first flange 21 has an annular shape and is positioned on the outer circumference of the pinion shaft 84. The first flange 21 protrudes toward the X1 side (one side in the first direction) from the reference surface 291 of the base 29 and the second surface 25 of the support portion 22. The outer circumferential surface 211 of the first flange 21 is a cylindrical surface extending along the axial direction of the central axis AX.

[0034] In other words, in a cross-section including the central axis AX, the outer circumferential surface 211 of the first flange 21 is a straight line extending in the X direction, but in this embodiment, it is not limited to a straight line extending in the X direction, and the outer circumferential surface 211 may have some irregularities. The support portion 22 extends radially outward relative to the first flange 21. The protrusion 23 is provided at the intersection of the first flange 21 and the support portion 22. The protrusion 23 projects toward the X1 side. The protrusion 23 has a rectangular shape in a cross-section including the central axis AX. The protrusion 23 has a first surface 24 toward the X1 side and a third surface 26 which is an outer circumferential surface toward the radially outward side. The first surface 24 extends radially perpendicular to the central axis AX. The first surface 24 is located toward the X1 side relative to the second surface 25 of the support portion 22.

[0035] The cover 1 has a second flange 14 positioned on the outer circumference of the first flange 21. The inner circumferential surface 141 of the second flange 14 is recessed radially outward relative to the outer circumferential surface 211 of the first flange 21. This creates a first gap 140 between the inner circumferential surface 141 of the second flange 14, the first flange 21, and the top surface 148. A sealing member 100, described later, is positioned in the first gap 140. The material of the cover 1 is not limited. It may be made of metal or resin.

[0036] For example, if the gearbox 2 is made of aluminum alloy and the cover 1 is made of resin, the cover 1 is more likely to have greater dimensional variations than the gearbox 2. According to the first embodiment, even with such a resin cover 1, sufficient sealing performance can be maintained.

[0037] The inner circumferential surface 141 of the second flange 14 has a straight portion 142 and a tapered portion 143. The straight portion 142 extends in the X direction. In other words, the straight portion 142 is a cylindrical surface that extends along the direction of the axis of the central axis AX. In other words, in a cross-section including the central axis AX, the straight portion 142 is a straight line extending in the X direction, but in this disclosure, it is not limited to a straight line extending in the X direction, and the straight portion 142 may have some irregularities. The straight portion 142 extends from one end 145 to a boundary portion 144 that connects to the tapered portion 143.

[0038] The tapered portion 143 is provided adjacent to the straight portion 142 on the X2 side. The diameter of the tapered portion 143 increases as it approaches the X2 side. The tapered portion 143 extends from the boundary portion 144 to the other end portion 146. The first surface 24 of the convex portion 23 overlaps with the straight portion 142 of the second flange 14 in the X direction. That is, in a cross section including the central axis AX, the extension line 240 (shown by the dashed line) of the first surface 24 is located at X1 relative to the boundary portion 144 and intersects with the straight portion 142. A bottom surface 147 is provided at the X2 side end of the second flange 14. In Figure 3, the bottom surface 147 and the second surface 25 are in contact, but in this disclosure, they do not have to contact. Also, a radius corner may be provided at the boundary portion 144.

[0039] Next, the procedure for attaching cover 1 to gearbox 2 and sealing it will be briefly explained. Figure 4 is a schematic diagram showing the sealing structure before attaching the cover to the gearbox. Figure 5 is a schematic diagram showing the sealing structure after attaching the cover to the gearbox.

[0040] As shown in Figure 4, before the cover 1 is attached to the gearbox 2, the sealing member 100 has not yet undergone elastic deformation, and therefore its cross-sectional shape is circular. Also, the area centroid C in the cross-section coincides with the center of the circle in the cross-section.

[0041] First, the sealing member 100 is attached to the gearbox 2. More specifically, the sealing member 100 is attached to the gearbox 2 with its outer circumferential surface in contact with the outer circumferential surface 211 of the first flange 21 and the first surface 24 of the protrusion 23.

[0042] Next, as shown in Figure 4, the cover 1 is moved towards X2 relative to the gearbox 2. That is, the cover 1 is moved in the direction P indicated by the arrow. Then, the tapered portion 143 of the second flange 14 comes into contact with the sealing member 100. In other words, the sealing member 100 comes into contact with three locations: the outer peripheral surface 211 of the first flange 21, the first surface 24 of the convex portion 23, and the tapered portion 143 of the second flange 14.

[0043] Then, when the cover 1 is further moved to the X2 side, as shown in FIG. 5, the tapered portion 143 acts as a guide for the seal member 100, and the portion contacting the seal member 100 changes from the tapered portion 143 to the straight portion 142. That is, in the state of FIG. 5, the seal member 100 abuts on three locations: the outer peripheral surface 211 of the first flange 21, the first surface 24 of the convex portion 23, and the straight portion 142 of the second flange 14. In the state of FIG. 5, the cross-sectional shape of the seal member 100 is a vertically long substantially elliptical shape. Therefore, the length of the contact portion of the straight portion 142 of the second flange 14 with the seal member 100 is, for example, longer than the radius of the seal member 100 in FIG. 4. As shown in FIG. 5, in a cross-section including the central axis AX, the area centroid C of the seal member 100 overlaps with the straight portion 142 of the second flange 14 in the X direction (the first direction). In other words, the area centroid C of the seal member 100 is located on the X1 side of the boundary portion 144 in the X direction (the first direction).

[0044] As described above, the steering device 80 according to the first embodiment includes a gearbox 2, an annular cover 1, and an annular seal member 100. The gearbox 2 has a first flange 21 protruding to the X1 side, a support portion 22 extending radially outward, and a convex portion 23 at the intersection of the outer peripheral surface 211 of the first flange 21 and the support portion 22. The cover 1 has a second flange 14 disposed on the outer peripheral side of the first flange 21. The inner peripheral surface 141 of the second flange 14 has a straight portion 142 and a tapered portion 143 whose diameter increases as it goes to the X2 side. The first surface 24 of the convex portion 23 is located on the X1 side with respect to the second surface 25 of the support portion 22.

[0045] In the first embodiment, the gearbox 2 is the first member, and the cover 1 is the second member.

[0046] The first member includes a base portion 29, a support portion 22 outside the base portion 29, a first flange 21 protruding to one side (X1 side) in the first direction from the support portion 22 and surrounding the base portion 29, and a convex portion 23 provided at the intersection of the outer peripheral surface 211 of the first flange 21 and the support portion 22 and protruding outward from the first flange 21.

[0047] The second member has a second flange 14 disposed outside the first flange 21. And the annular seal member 100 is a sealing structure disposed between the first member and the second member.

[0048] The inner peripheral surface 141, which is the facing surface of the second flange facing the first flange 21, has a straight portion 142 extending in the X direction and a tapered portion 143 provided adjacent to the other side (X2 side) in the X direction with respect to the straight portion 142 and having a diameter increasing as going to the other side (X2 side) in the X direction. And the first surface 24, which is the surface on one side (X1 side) in the X direction of the convex portion 23, is located on one side (X1 side) in the X direction with respect to the second surface 25, which is the surface on one side (X1 side) in the X direction of the support portion 22.

[0049] The sealing structure can be applied to the sealing of the MCU of the motor 91 in addition to the periphery of the above-described pinion shaft.

[0050] As described above, in the gearbox according to Patent Document 1, the second flange is located on the outer peripheral side of the first flange. The inner periphery of the second flange has a straight portion and a tapered portion whose diameter increases as going to the other side in the axial direction. The outer peripheral portion of the seal member is pressed against the tapered portion of the second flange. Therefore, a force is applied from the seal member to the tapered portion in a direction in which the second flange located on the outer peripheral side with respect to the first flange spreads outward. As a result, there is a possibility that the sealing performance between the first flange and the second flange deteriorates.

[0051] In contrast, in the first embodiment, a protrusion 23 projecting toward X1 is provided at the intersection of the outer peripheral surface 211 of the first flange 21 and the support portion 22. The first surface 24 of the protrusion 23 is located on the X1 side relative to the second surface 25 of the support portion 22. Therefore, the sealing member 100 abuts against the outer peripheral surface 211 of the first flange 21, the first surface 24 of the protrusion 23, and the inner peripheral surface 141 of the second flange 14. Thus, in this embodiment, compared to Patent Document 1, a protrusion 23 projecting toward X1 is provided, and the first surface 24 of the protrusion 23 is located on the X1 side relative to the second surface 25 of the support portion 22. Therefore, since the sealing member 100 according to this embodiment is located further toward X1 than the sealing member according to Patent Document 1, the sealing member 100 is more likely to abut against the straight portion 142 and less likely to abut against the tapered portion 143. This makes it less likely for force to be applied from the sealing member 100 to the tapered portion 143, and consequently, prevents a decrease in the sealing performance between the first flange 21 and the second flange 14.

[0052] Furthermore, the seal structure described in Patent Document 1 employs a so-called three-sided (triangular) seal structure. This three-sided (triangular) seal structure has the disadvantages of being difficult to achieve relative positional accuracy between the three surfaces, and the high filling rate of the seal member making the seal member prone to deterioration. In contrast, in this embodiment, since the seal is formed by sealing on two surfaces, the straight portion 142 of the second flange 14 of the cover 1 and the outer peripheral surface 211 of the gearbox 2, it is only necessary to manage the relative positional accuracy (distance between the two surfaces), making it easier to improve the sealing performance of the seal member 100.

[0053] The first surface 24 of the protrusion 23 overlaps with the straight portion 142 of the second flange 14 when viewed from the radial direction.

[0054] As a result, when the sealing member 100 is placed on the first surface 24 of the protrusion 23, the sealing member 100 is more likely to come into contact with the straight portion 142 of the second flange 14, and less likely to come into contact with the tapered portion 143. Therefore, a decrease in the sealing performance between the first flange 21 and the second flange 14 is suppressed.

[0055] In a cross-section including the central axis AX of the pinion shaft 84, the area centroid C of the sealing member 100 overlaps with the straight portion 142 of the second flange 14 when viewed from the radial direction.

[0056] As a result, the sealing member 100 is more likely to come into contact with the straight portion 142 and less likely to come into contact with the tapered portion 143, thereby suppressing a decrease in the sealing performance between the first flange 21 and the second flange 14.

[0057] [Second Embodiment] Next, a second embodiment will be described, but parts with the same configuration as the first embodiment described above will be given the same reference numerals and their descriptions will be omitted. In the second embodiment, the X-direction position of the first surface of the protrusion differs from that of the first embodiment. This will be described in detail below. Figure 6 is a schematic diagram showing a cross-section of the seal structure between the cover and the gearbox according to the second embodiment. Figure 7 is a schematic diagram showing the seal structure before the cover is attached to the gearbox. Figure 8 is a schematic diagram showing the seal structure after the cover has been attached to the gearbox.

[0058] As shown in Figure 6, in the seal structure 200A according to the second embodiment, the first flange 21A is positioned opposite the straight portion 142 of the second flange 14. The radial distance between the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21A is defined as the second distance D2. In the second embodiment, the radial distance between the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21A is the same at any position on the inner circumferential surface 141 in the X direction. In other words, the maximum distance between the first flange 21A and the straight portion 142 is the second distance D2.

[0059] A protrusion 23A is provided at the intersection of the first flange 21A and the support portion 22. The protrusion 23A projects toward the X1 side. The protrusion 23A has a substantially trapezoidal shape in a cross-section including the central axis AX. The protrusion 23A has a first surface 24A toward the X1 side and a third surface 26A, which is an outer peripheral surface, toward the radially outward side. The first surface 24A extends in the radial direction perpendicular to the central axis AX. The diameter of the third surface 26A increases toward the X2 side. The first surface 24A is located toward the X1 side relative to the second surface 25 of the support portion 22. The third surface 26A of the protrusion 23A is positioned opposite the tapered portion 143 of the second flange 14.

[0060] In other words, a second gap 140A is provided between the third surface 26A and the tapered portion 143. The width of the second gap 140A is largest at the end on the X1 side and gradually decreases towards the X2 side. In other words, the distance between the third surface 26A and the tapered portion 143 is greatest at the end on the X1 side and gradually decreases towards the X2 side. Let the maximum value of the distance between the third surface 26A and the tapered portion 143 be the first distance D1. The first distance D1 is smaller than the second distance D2. Also, the first surface 24A of the convex portion 23A overlaps with the tapered portion 143 of the second flange 14 when viewed from the radial direction. That is, in a cross-section including the central axis AX, the extension line 240A (shown by the dashed line) of the first surface 24A is located on the X2 side relative to the boundary portion 144 and intersects with the tapered portion 143.

[0061] Next, the procedure for attaching and sealing cover 1 to gearbox 2A will be briefly explained. Figure 7 is a schematic diagram showing the sealing structure before the cover is attached to the gearbox. Figure 8 is a schematic diagram showing the sealing structure after the cover is attached to the gearbox.

[0062] As shown in Figure 7, before the cover 1 is attached to the gearbox 2, the sealing member 100 has not yet undergone elastic deformation, and therefore its cross-sectional shape is circular. Also, the area centroid C in the cross-section coincides with the center of the circle in the cross-section.

[0063] First, the sealing member 100 is attached to the gearbox 2. More specifically, the sealing member 100 is attached to the gearbox 2A with its outer circumferential surface in contact with the outer circumferential surface 211 of the first flange 21A and the first surface 24A of the protrusion 23.

[0064] Next, as shown in Figure 7, when the cover 1 is moved towards X2 relative to the gearbox 2A, the sealing member 100 comes into contact with three locations: the outer peripheral surface 211 of the first flange 21A, the first surface 24A of the protrusion 23A, and the tapered portion 143 of the second flange 14.

[0065] Then, when the cover 1 is moved further toward X2, as shown in Figure 8, the tapered portion 143 acts as a guide for the sealing member 100, and the portion that contacts the sealing member 100 changes from the tapered portion 143 to the straight portion 142. That is, in the state shown in Figure 8, the sealing member 100 contacts three places: the outer peripheral surface 211 of the first flange 21A, the first surface 24A of the convex portion 23A, and the second flange 14. More specifically, the portion of the second flange 14 that the sealing member 100 contacts is mainly the straight portion 142, but a part of it may also contact the tapered portion 143. In the state shown in Figure 8, the cross-sectional shape of the sealing member 100 elastically deforms into a vertically elongated, approximately elliptical shape. The length of the portion of the straight portion 142 of the second flange 14 that contacts the sealing member 100 is, for example, longer than the radius of the sealing member 100 in Figure 7. As shown in Figure 8, in a cross-section including the central axis AX, the area centroid C of the sealing member 100 overlaps with the straight portion 142 of the second flange 14 in the X direction (first direction). In other words, the area centroid C of the sealing member 100 is located on the X1 side of the boundary portion 144 in the X direction (first direction).

[0066] As described above, in the second embodiment, the first surface 24A of the protrusion 23A overlaps with the tapered portion 143 of the second flange 14 when viewed from the radial direction.

[0067] As in the first embodiment described above, if the height of the protrusion 23 is increased so that the first surface 24 of the protrusion 23 overlaps with the straight portion 142 of the second flange 14 when viewed from the radial direction, the protrusion 23 is more likely to come into contact with the inner circumferential surface 141 of the second flange 14 due to dimensional variations during manufacturing. Therefore, the height of the protrusion 23A was set to be lower to make it less likely to come into contact with the inner circumferential surface 141 of the second flange 14.

[0068] The first distance D1, which is the maximum distance between the third surface 26A and the tapered portion 143, is smaller than the second distance D2, which is the maximum distance between the outer peripheral surface 211 of the first flange 21A and the straight portion 142.

[0069] If the height of the protrusion 23A is made lower so that the first surface 24A of the protrusion 23A overlaps with the tapered portion 143 of the second flange 14 when viewed radially, a portion of the elastically deformed sealing member 100 can easily enter the second gap 140A between the third surface 26A of the protrusion 23A and the tapered portion 143 of the second flange 14. If a large amount of the sealing member 100 enters the second gap 140A, the sealing performance between the first flange 21A and the second flange 14 will decrease. Therefore, in order to reduce the width of the second gap 140A and decrease the amount of the sealing member 100 that enters the second gap 140A, the first distance D1 was made smaller than the second distance D2.

[0070] [Reference Example 1] Next, Reference Example 1 will be described. Figure 9 is a schematic diagram showing the seal structure in Reference Example 1 before the cover is attached to the gearbox. Figure 10 is a schematic diagram showing the seal structure in Reference Example 1 after the cover has been attached to the gearbox. Reference Example 1 differs from the first and second embodiments in that there is no protrusion on the gearbox and in the shape of the seal member. This will be explained in detail below.

[0071] As shown in Figure 9, in the seal structure 200B according to Reference Example 1, the gearbox 2B does not have a protrusion. That is, the gearbox 2B comprises a first flange 21B and a support portion 22, with the support portion 22 extending radially outward from the X2 side end of the first flange 21B. Furthermore, the cross-sectional shape of the seal member 100B before force is applied is a vertically elongated, approximately rectangular shape, with the four corners 100B1 of the cross section being curved. The radial length of the seal member 100B is slightly greater than the radial distance between the inner circumferential surface of the straight portion 142 of the second flange 14 and the outer circumferential surface 211 of the first flange. Also, the area centroid C1 of the cross section of the seal member 100B coincides with the centroid of the rectangle in the cross section. In the state shown in Figure 9, the sealing member 100B contacts three locations: the outer peripheral surface 211 of the first flange 21B, the second surface 25 of the support portion 22, and the tapered portion 143 of the second flange 14.

[0072] Next, as shown in Figure 10, when the cover 1 is moved towards X2 relative to the gearbox 2B, the tapered portion 143 acts as a guide for the sealing member 100, and the portion of the second flange 14 that abuts the sealing member 100 changes from the tapered portion 143 to the straight portion 142. That is, in the state shown in Figure 10, the sealing member 100B mainly abuts at three locations: the outer peripheral surface 211 of the first flange 21B, the second surface 25 of the support portion 22, and the second flange 14. More specifically, the portion of the second flange 14 that the sealing member 100B abuts is mainly the straight portion 142, but a part of it may also abut the tapered portion 143.

[0073] For example, if the gearbox 2 is made of aluminum alloy and the cover 1 is made of resin, at high temperatures, the cover 1 will deform more than the gearbox 2 due to the difference in thermal expansion. The coefficient of linear expansion of aluminum alloy is, for example, 2.3 × 10⁻⁶. －５ The temperature is [ / °C]. The resin of cover 1 is, for example, glass fiber reinforced polybutylene terephthalate. If the polybutylene terephthalate contains 30% glass fiber, the coefficient of linear expansion of cover 1 is, for example, 6.5 × 10⁻⁶. －５The temperature is [ / °C]. At high temperatures, the cover 1 deforms more than the gearbox 2 due to the difference in thermal expansion. Therefore, in order to improve sealing performance even at high temperatures, it is necessary to keep the first gap 140 at room temperature (25°C) small. As shown in Figure 10, when the distance between the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21 becomes small, the area in contact between the sealing member 100 and the tapered portion 143 increases.

[0074] In contrast, as shown in Figure 5, in the first embodiment, even if the distance between the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21 is reduced, the sealing member 100 is less likely to come into contact with the tapered portion 143, and the sealing member 100 is more likely to adhere closely to the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21. The sealing structure of the first embodiment has higher sealing performance than the sealing structure of Reference Example 1.

[0075] [Reference Example 2] Next, Reference Example 2 will be explained. Figure 11 is a schematic diagram showing the seal structure in Reference Example 2 before the cover is attached to the gearbox. Figure 12 is a schematic diagram showing the seal structure in Reference Example 2 after the cover has been attached to the gearbox. Reference Example 2 differs from Reference Example 1 in the shape of the seal member. This will be explained in detail below.

[0076] As shown in Figure 11, in the seal structure 200C according to Reference Example 2, the gearbox 2B and the second flange 14 of the cover 1 have the same configuration as in Reference Example 1. The cross-sectional shape of the seal member 100C before force is applied is a vertically elongated, approximately elliptical shape. In detail, the end 100C1 on the X1 side and the end 100C2 on the X2 side have a semicircular shape, and the space between the end on the X1 side and the end on the X2 side is a vertically elongated rectangle. Therefore, the cross-sectional shapes of the outer circumferential surface 100C3 and the inner circumferential surface 100C4 in this vertically elongated rectangular portion are straight lines. The radial length of the seal member 100C is slightly greater than the radial distance between the inner circumferential surface of the straight portion 142 of the second flange 14 and the outer circumferential surface 211 of the first flange. Also, the area centroid C2 in the cross-section coincides with the centroid of the approximately ellipse in the cross-section. In the state shown in Figure 11, the sealing member 100C contacts three locations: the outer peripheral surface 211 of the first flange 21B, the second surface 25 of the support portion 22, and the tapered portion 143 of the second flange 14.

[0077] Next, as shown in Figure 12, when the cover 1 is moved towards X2 relative to the gearbox 2B, the tapered portion 143 acts as a guide for the seal member 100, and the portion that contacts the seal member 100C changes from the tapered portion 143 to the straight portion 142. That is, in the state shown in Figure 12, the seal member 100C mainly contacts three locations: the outer peripheral surface 211 of the first flange 21B, the second surface 25 of the support portion 22, and the second flange 14. More specifically, the portion of the second flange 14 that the seal member 100C contacts is mainly the straight portion 142, but a part of it may also contact the tapered portion 143.

[0078] As explained above, according to Reference Examples 1 and 2, even in a seal structure without protrusions, by applying a seal member 100B having a vertically elongated, substantially rectangular shape or a seal member 100C having a vertically elongated, substantially elliptical shape, the area of ​​the tapered portion 143 that the seal members 100B and 100C contact becomes smaller. As a result, the seal members 100B and 100C are more likely to contact the straight portion 142 and less likely to contact the tapered portion 143, thereby suppressing a decrease in the sealing performance between the first flange 21B and the second flange 14.

[0079] [Comparison of the First Embodiment with a Comparative Example] Next, a comparison of the first embodiment with a comparative example will be described. Figure 13 is an enlarged view of portion A in Figure 2 according to the first embodiment. Figure 14 is an enlarged view corresponding to portion A in Figure 2 according to the comparative example. As shown in Figure 13, the inner diameter of the enlarged lower end portion 13 of the cover 1 (see Figure 2) of the first embodiment is radius Ra from the central axis AX (see Figure 2) of the pinion shaft 84. The inner diameter of the first flange 21 of the first embodiment is radius Rb from the central axis AX (see Figure 2). Radius Ra is larger than radius Rb.

[0080] As shown in Figure 14, in the comparative example, the first flange 21C has an annular shape extending along the axial direction of the central axis AX (see Figure 2). A second flange 14A is provided at the lower end enlarged diameter portion 13A of the cover 1 (see Figure 2). In the comparative example, the second flange 14A is located inside the first flange 21C. When the position of the first flange 21C relative to the base portion 29 is the same, the sealing structure of the first embodiment can provide a wider internal space surrounded by the cover 1 (see Figure 2) compared to the sealing structure of the comparative example.

[0081] [Third Embodiment] Figure 15 is a schematic diagram showing the seal structure after the cover according to the third embodiment has been attached to the gearbox. In describing the sealing structure of the third embodiment, the same structure as in the first embodiment will not be described. In the third embodiment, there is a gap G between the bottom surface 147 and the second surface 25. Even with the gap G, the sealing structure of the third embodiment makes it easy for the sealing member 100 to adhere closely to the inner circumferential surface 141 of the second flange 14 and the outer circumferential surface 211 of the first flange 21, so foreign matter is less likely to enter through the gap G.

[0082] The present disclosure may adopt the following embodiments: (1) A pinion shaft extending from inside the vehicle interior to outside the vehicle interior; a gearbox located outside the vehicle interior and connected to the pinion shaft; an annular cover covering the outer circumference of the pinion shaft; and an annular sealing member located between the gearbox and the cover and provided on the outer circumference side of the pinion shaft, wherein the axial direction of the central axis of the pinion shaft is defined as a first direction, the inside of the vehicle interior is one side of the first direction, and the outside of the vehicle interior is the other side of the first direction; the gearbox has a first flange located on the outer circumference side of the pinion shaft and projecting toward one side of the first direction; a support portion extending radially outward from the other side of the first direction on the first flange; and a convex portion provided at the intersection of the outer circumference surface of the first flange and the support portion and projecting toward one side of the first direction; the cover has a second flange located on the outer circumference side of the first flange; and the sealing member is located between the first flange and the second flange. (1) The steering device, wherein the inner circumferential surface of the second flange has a straight portion extending in the first direction and a tapered portion provided adjacent to the other side in the first direction relative to the straight portion and whose diameter increases as it goes toward the other side in the first direction, and the first surface, which is the surface on one side in the first direction of the protrusion, is located on one side in the first direction relative to the second surface, which is the surface on one side in the first direction of the support portion. (2) The steering device according to (1), wherein the pinion shaft is connected to the steering wheel and provided through the vehicle body panel, and the cover is positioned between the vehicle body panel and the gearbox, and one side in the first direction is the vehicle body panel side relative to the gearbox, and the other side in the first direction is the gearbox side relative to the vehicle body panel. (3) The steering device according to (1) or (2), wherein the first surface of the protrusion overlaps with the straight portion of the second flange when viewed radially. (4) The steering device according to (1) or (2), wherein the first surface of the protrusion overlaps with the tapered portion of the second flange when viewed from the radial direction.(5) The steering device according to (4), wherein the third surface, which is the radially outer surface of the protrusion, is positioned opposite the tapered portion of the second flange, the first flange is positioned opposite the straight portion of the second flange, and the first distance, which is the maximum distance between the third surface and the tapered portion, is smaller than the second distance, which is the maximum distance between the outer surface of the first flange and the straight portion. (6) The steering device according to any one of (1) to (5), wherein, in a cross section of the pinion shaft including the central axis, the area centroid of the sealing member overlaps with the straight portion of the second flange when viewed from the radial direction.

[0083] 1 Cover 11 Main body 12 Upper end enlarged diameter section 13 Lower end enlarged diameter section 14 Second flange 140 First gap 140A Second gap 141 Inner circumferential surface 142 Straight section 143 Tapered section 144 Boundary section 145 One end 146 Other end 147 Bottom surface 148 Top surface 2, 2A, 2B Gearbox 21 First flange 211 Outer circumferential surface 21A, 21B First flange 22 Support section 23, 23A Protrusion 24, 24A First surface 29 Base section 240, 240A Extension line 25 Second surface 26, 26A Third surface 80 Steering device 81 Steering wheel 82 Steering shaft 83 Intermediate shaft 84 Pinion shaft 841 First shaft 841a End 842 Second shaft 842a End 843 Torsion bar 85, 86 Universal joint 87 Reduction mechanism 871 Worm wheel 872 Worm gear 88 Pinion gear 89 Rack shaft 91 Motor 92 Dash panel 93 Floor panel (body panel) 93a Through hole 94 Gasket 95 Sliding bearing 96 Torque sensor 97 Needle bearing 100 Seal member 100B Seal member 100B1 Corner 100C Seal member 100C1, 100C2 End 100C3 Outer surface 100C4 Inner surface 200 Seal structure 200A, 200B, 200C Seal structure AX Center axis C, C1, C2 Area centroid D1 1st distance D2 2nd distance IN Inside the vehicle OUT Outside the vehicle

Claims

1. A steering device comprising: a first member having a base, a support portion located outside the base, a first flange protruding from the support portion to one side in the first direction and surrounding the base, and a convex portion provided at the intersection of the outer peripheral surface of the first flange and the support portion and protruding outward from the first flange; a second member having a second flange positioned outside the first flange and fixed to the first member; and an annular sealing member positioned between the first member and the second member, wherein the opposing surface of the second flange facing the first flange has a straight portion extending in the first direction and a tapered portion provided adjacent to the other side in the first direction relative to the straight portion and whose diameter increases as it goes toward the other side in the first direction; and the first surface, which is the surface of the convex portion on one side in the first direction, is located on one side in the first direction relative to the second surface, which is the surface of the support portion on one side in the first direction.

2. The steering device according to claim 1, wherein the first member is made of metal and the second member is made of resin.

3. A steering device according to claim 1 or 2, comprising a pinion shaft extending from inside the vehicle interior to outside the vehicle interior, wherein the first member is a gearbox, the gearbox is located outside the vehicle interior and connected to the pinion shaft, the second member is an annular cover covering the outer circumference of the pinion shaft, and the sealing member is located between the gearbox and the cover and provides a seal.

4. The steering device according to claim 3, wherein the pinion shaft is connected to the steering wheel and is provided through the vehicle body panel, the cover is positioned between the vehicle body panel and the gearbox, one side in the first direction is on the vehicle body panel side relative to the gearbox, and the other side in the first direction is on the gearbox side relative to the vehicle body panel.

5. In a cross-section including the central axis of the pinion shaft, the area centroid of the sealing member overlaps with the straight portion of the second flange when viewed from the radial direction, as described in claim 3 or 4.

6. The steering device according to any one of claims 1 to 5, wherein the first surface of the protrusion overlaps with the straight portion of the second flange when viewed from the radial direction.

7. The steering device according to any one of claims 1 to 5, wherein the first surface of the convex portion overlaps with the tapered portion of the second flange when viewed from the radial direction.

8. The steering device according to claim 7, wherein the third surface, which is the radially outer surface of the protrusion, is positioned opposite the tapered portion of the second flange, the first flange is positioned opposite the straight portion of the second flange, and the first distance, which is the maximum distance between the third surface and the tapered portion, is smaller than the second distance, which is the maximum distance between the outer circumferential surface of the first flange and the straight portion.

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