Steering device

Abstract

A steering device includes a steering shaft inputting a rotational force from a steering wheel, a transmission mechanism transmitting the rotational force of the steering shaft to steered wheels, a torque sensor provided at a periphery of the steering shaft and detecting a steering torque of the steering shaft, a housing having an opening surface through which the steering shaft passes, accommodating a part of the steering shaft, and provided, on an inner peripheral surface of an axial end portion of the housing, with a stepped portion whose diameter is enlarged stepwise, an annular seal member provided at the stepped portion, and an annular cover member covering an opening end surface of the housing. The cover member is provided, at a portion facing the opening end surface of the housing on a back surface of the cover member, with at least one annular protrusion protruding toward the opening end surface.

Description

[0001] DESCRIPTION

[0002] TITLE : STEERING DEVICE

[0003] TECHNICAL FIELD

[0004] [ 0001. ] The present disclosure relates to a steering device .

[0005] BACKGROUND ART

[0006] [ 0002. ] Japanese Patent No . 7003287 (hereinafter is referred to as JP7003287 or Patent Document 1 ) discloses a steering device . This steering device includes a steering shaft inputting a rotational force from a steering wheel, and a housing having an opening surface through which the steering shaft passes, and accommodating therein a part of the steering shaft . The steering device has, on an inner peripheral surface of an axial end portion on the opening surface side thereof, a stepped portion having a stepped enlarged-diameter shape whose diameter is enlarged stepwise toward an opposite side to the steering wheel in an axial direction of the steering shaft . This stepped portion is provided with an annular seal member that seals a gap between the inner peripheral surface of the housing and an outer peripheral surface of the steering shaft .

[0007] [ 0003. ] Furthermore, the steering shaft is provided, at a position on a vertically lower side with respect to the seal member, with a torque sensor for detecting a steering torque of the steering shaft .[ 0004. ] In addition, an annular cover member that covers an opening end surface of the housing is provided at an outer periphery of the steering shaft .

[0008] CITATION LIST PATENT DOCUMENT

[0009] [ 0005. ] Patent Document 1 : Japanese Patent No .

[0010] 7003287

[0011] SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0012] [ 0006. ] The steering device disclosed in Patent Document 1 is generally disposed in an engine compartment . When water, such as rainwater or muddy water, is splashed up by steered wheels and enters the engine compartment, this water may accumulate in a space at an upper portion of the seal member through a gap between the opening end face of the housing and a back surface of the cover member . If this water causes deterioration of the seal member or corrosion of the housing and then flows downward vertically beyond the seal member, the water reaches the torque sensor containing various electronic components and causes failure of those electronic components .

[0013] [ 0007. ] For this problem, however, Patent Document 1 provides no countermeasures against the failure of electronic components caused by the water .

[0014] [ 0008. ] The present invention was made in view of the above problem. An obj ect of the present invention is therefore to provide a steering devicethat is capable of suppressing failure of electronic components caused by water .

[0015] SOLUTION TO PROBLEM

[0016] [ 0009. ] According to one aspect of the present invention, a steering device comprises : a steering shaft structured to input a rotational force from a steering wheel; a transmission mechanism configured to transmit the rotational force of the steering shaft to steered wheels; a torque sensor provided at a periphery of the steering shaft and detecting a steering torque of the steering shaft; a housing having an opening surface through which the steering shaft passes and accommodating a part of the steering shaft, the housing provided, on an inner peripheral surface of an axial end portion located on a side of the opening surface of the housing, with a stepped portion whose diameter is enlarged stepwise toward an opposite side to the steering wheel in an axial direction of the steering shaft; an annular seal member provided at the stepped portion and sealing a gap between the inner peripheral surface of the housing and an outer peripheral surface of the steering shaft; and an annular cover member provided on an outer periphery of the steering shaft and covering an opening end surface of the housing, the cover member provided, at a portion facing the opening end surface of the housing on a back surface of the cover member, with at least one annular protrusion protruding toward the opening end surface .EFFECTS OF INVENTION

[0017] [ 0010. ] According to the present invention, it is possible to suppress failure of electronic components caused by water .

[0018] BRIEF DESCRIPTION OF DRAWINGS

[0019] [ 0011 . ]

[0020] Fig. 1 is a longitudinal cross section of a steering device according to a first embodiment .

[0021] Fig. 2 is an enlarged local sectional view of the steering device shown in Fig. 1.

[0022] Fig. 3A is a cross section of a cover member, taken by being cut along an axial direction of a steering shaft . Fig. 3B is a back view of the cover member, viewed from an arrow direction A of Fig. 3A.

[0023] Fig. 4 is an enlarged local sectional view of a steering device according to a second embodiment . Fig. 5 is an enlarged local sectional view of a steering device according to a third embodiment . Fig. 6 is an enlarged local sectional view of a steering device according to a fourth embodiment . Fig. 7 is an enlarged local sectional view of a steering device according to a fifth embodiment . Fig. 8 is an enlarged local sectional view of a steering device according to a sixth embodiment . Fig. 9A is a back view of a cover member of a steering device according to a ninth embodiment . Fig. 9B is a cross section of the cover member, cut along a line A-A of Fig. 9A.

[0024] Fig. 10 is an enlarged local sectional view of a steering device according to an eighth embodiment .DESCRIPTION OF EMBODIMENTS

[0025] [ 0012. ] Embodiments of a steering device according to the present invention will be described below with reference to the drawings .

[0026] [ 0013. ] Fig. 1 is a longitudinal cross section of a steering device according to a first embodiment .

[0027] Fig. 2 is an enlarged local sectional view of the steering device shown in Fig. 1. In Figs . 1 and 2, for convenience of the following description, a longitudinal direction of a steering shaft 5 is referred to as an "axial direction", a direction orthogonal to the steering shaft 5 is referred to as a "radial direction", and a direction of a circumference of the steering shaft 5 is referred to as a "circumferential direction" . Furthermore, a side in the axial direction on which the steering shaft 5 is linked to a steering wheel (not shown) is referred to as "one end side", and a side in the axial direction on which the steering shaft 5 is linked to a piston 18 is referred to as "the other end side" . Fig. 3A is a cross section of a cover member 41, taken by being cut along the axial direction of the steering shaft 5. Fig. 3B is a back view of the cover member 41, viewed from an arrow direction A of Fig. 3A.

[0028] [ 0014. ] The steering device is an integral type steering device used for heavy-duty vehicles etc . The steering device is configured mainly by a steering device main body 1, an electric motor (not shown) , and an EPS controller (ECU) (not shown) .[ 0015. ] The steering device main body 1 includes a steering mechanism 2, a sector shaft 3, and a power cylinder 4 .

[0029] [ 0016. ] The steering mechanism 2 is configured to input a steering operation (a rotational force) from the steering wheel (not shown) . The steering mechanism 2 includes the steering shaft 5. A part of the steering shaft 5 is accommodated in a housing 6. As illustrated in Fig. 1, the steering shaft 5 has an input shaft 7, a connecting shaft 8, an intermediate shaft 9, and an output shaft 10.

[0030] [ 0017. ] The input shaft 7 is formed into a cylindrical tubular shape . One end side of the input shaft 7 is linked to the steering wheel, to input a steering torque of a driver . The input shaft 7 is disposed such that one end portion of the input shaft 7 passes through an opening surface Ila of an input-side housing 11 of the housing 6 as illustrated in Fig. 2, and the other end portion is inserted into the substantially cylindrical tubular connecting shaft 8 as illustrated in Figs . 1 and 2.

[0031] [ 0018. ] The connecting shaft 8 accommodates, on its one end side, the other end portion of the input shaft 7, and its other end side is connected to the intermediate shaft 9 via an after-mentioned spline portion 13, thereby connecting the input shaft 7 and the intermediate shaft 9. As can be seen in Fig. 1, the connecting shaft 8 is formed into a cylindrical tubular shape whose diameter is reduced stepwise from its one end side toward its other end side, andhas a large diameter cylindrical tubular portion 8a located on its one end side, and a small diameter cylindrical tubular portion 8b formed integrally with the large diameter cylindrical tubular portion 8a and having a diameter smaller than the large diameter cylindrical tubular portion 8a .

[0032] Furthermore, an annular protruding portion 8c protruding outwards in the radial direction is formed at a slightly upper side with respect to an axially middle position of the large diameter cylindrical tubular portion 8a .

[0033] [ 0019. ] As shown in Fig. 1, a bearing, e . g. a first ball bearing 12, for rotatably supporting the connecting shaft 8 is provided between an outer peripheral portion of the annular protruding portion 8c and an inner peripheral wall of the input-side housing 11 that forms a part of the housing 6.

[0034] [ 0020. ] An outer peripheral portion of the small diameter cylindrical tubular portion 8b is fixed to an inner peripheral portion of an accommodation recess formed at one axial end of the intermediate shaft 9, via the spline portion 13.

[0035] [ 0021. ] The intermediate shaft 9 is connected, on its one end side, to the input shaft 7 via a first torsion bar 14 so as to be able to rotate relative to the input shaft 7. The other end side of the intermediate shaft 9 is inserted into an opening recess formed at one end side enlarged-diameter portion of the output shaft 10. The intermediate shaft 9 is provided, at its one end side outerperipheral portion, with a speed reducer that is connected to the electric motor (not shown) and that is formed by a worm gear formed by engagement between a worm shaft (not shown) and a worm wheel 15.

[0036] [ 0022. ] The output shaft 10 is connected, on its one end side, to the intermediate shaft 9 via a second torsion bar 16 so as to be able to rotate relative to the intermediate shaft 9. The output shaft 10 outputs a steering torque that is input by the intermediate shaft 9, to the piston 18 via a ball screw mechanism 17 serving as a conversion mechanism.

[0037] [ 0023. ] The ball screw mechanism 17 is configured by the output shaft 10, as a screw shaft, provided with a ball groove 10a that is a spiral groove formed at an outer peripheral portion on the other end side of the output shaft 10, the piston 18, as a nut, provided with a ball groove 18a that is a spiral groove corresponding to the ball groove 10a and that is formed at an inner peripheral portion of the piston 18 which faces the outer peripheral portion of the output shaft 10, and a plurality of balls 19 provided between the ball groove 18a of the piston 18 and the ball groove 10a of the output shaft 10.

[0038] [ 0024. ] As illustrated in Fig. 1, a well-known rotary valve 20, as a control valve, is configured between the intermediate shaft 9 and the output shaft 10. The rotary valve 20 selectively supplieshydraulic fluid, provided by a pump device (not shown) mounted on a vehicle, to after-described first and second fluid chambers (pressure chambers) Pl and P2 according to an amount and a direction of torsion of the second torsion bar 16, which is derived from the relative rotational angle between the intermediate shaft 9 and the output shaft 10.

[0039] [ 0025. ] The sector shaft 3 has a sector gear 3a, which is engaged with rack teeth 18b of the piston 18 provided at the other end side outer periphery of the steering shaft 5. The sector shaft 3 rotates by this engagement between the sector gear 3a and the rack teeth 18b in response to axial movement of the piston 18. The sector shaft 3 is linked to steered wheels via a pitman arm (not shown) , for steering the steered wheels .

[0040] [ 0026. ] As described above, the ball screw mechanism 17, the sector shaft 3 and the pitman arm constitute a transmission mechanism that converts the rotational force (steering force) input to the steering shaft 5 into a steering force of the steered wheels . Here, when the steering device is configured without using the ball screw mechanism 17 etc . , for instance, a rack-and-pinion mechanism having a rack bar, a pinion shaft etc . can be used as the conversion mechanism.

[0041] [ 0027. ] The power cylinder 4 is configured such that the tubular piston 18 slidably accommodated in the housing 6 defines the pair of first and second fluid chambers Pl and P2 . The power cylinder 4serves as a hydraulic actuator that generates an assist torque that assists the steering torque .

[0042] [ 0028. ] A torque sensor 21 is disposed in the input-side housing 11 so that most of the torque sensor 21 is positioned on a ground side with respect to an after-mentioned dust seal 40 in the axial direction of the steering shaft 5. As illustrated in Figs . 1 and 2, the torque sensor 21 is provided at a periphery of an outer peripheral portion of the connecting shaft 8 on one end side with respect to the annular protruding portion 8c, with the first torsion bar 14 passing through the inside of the annular torque sensor 21. The torque sensor 21 mainly has a permanent magnet 22, a pair of first and second yokes 23 and 24, a pair of first and second magnetic flux collection rings (magnetic concentrator rings) 25 and 26, and a magnetic sensor 27. The permanent magnet 22, the first and second yokes 23 and 24, and the magnetic flux collection rings 25 and 26 are each arranged almost concentrically with the rotation axis of the steering shaft 5.

[0043] [ 0029. ] The permanent magnet 22 is formed into a substantially cylindrical tubular shape with a magnetic material . The permanent magnet 22 is a magnetic member fixed to the outer periphery of the one end portion of the connecting shaft 8. The permanent magnet 22 is configured such that N-poles and S-poles are alternately arranged (magnetized)along a circumferential direction of the permanent magnet 22 .

[0044] [ 0030. ] The pair of first and second yokes 23 and 24 are each formed into a substantially cylindrical tubular shape with a soft magnetic material . The first and second yokes 23 and 24 are provided such that one end sides, located on the intermediate shaft 9 side, of both first and second yokes 23 and 24 are circumferentially arranged on a line along the circumferential direction, and face the permanent magnet 22 in the radial direction. On the other hand, the other end side of the first yoke 23 is located on an inner side, and other end side of the second yoke 24 is located on an outer side so as to face each other in the radial direction.

[0045] [ 0031. ] The pair of first and second magnetic flux collection rings 25 and 26 are substantially annular rings that collect (concentrate) the magnetic flux leaked from the permanent magnet 22 toward the other end sides of the first and second yokes 23 and 24 within a predetermined range . The first and second magnetic flux collection rings 25 and 26 are arranged between the other end sides of the yokes 23 and 24 in the radial direction. The magnetic flux collection ring 25 is located on an outer side, and the magnetic flux collection ring 26 is located on an inner side so as to face each other in the radial direction. A Hall element 28 is disposed between the magnetic flux collection rings 25 and 26 in the radial direction. A magnetic flux collection portion25a formed by being pressed inwards in the radial direction is provided at a predetermined position in the circumferential direction of the magnetic flux collection ring 25. On the other hand, a magnetic flux collection portion 26a protruding outwards in the radial direction is provided at a position, facing the magnetic flux collection portion 25a, in the circumferential direction of the magnetic flux collection ring 26.

[0046] [ 0032. ] The magnetic sensor 27 is configured by the Hall element 28 accommodated and disposed in a gap between the magnetic flux collection portions 25a and 26a in the radial direction, and a first connecting terminal 30 for connecting the Hall element 28 to a control board 29 provided above the torque sensor 21. The magnetic sensor 27 detects magnetic flux passing through between the magnetic flux collection portions 25a and 26a by the Hall element 28, by utilizing Hall effect by the Hall element 28, and outputs a signal according to this detected magnetic flux to the control board 29. The control board 29 then performs calculation of a relative rotational angle between the input shaft 7 and the intermediate shaft 9, and calculation of a steering torque based on the relative rotational angle .

[0047] [ 0033. ] The control board 29 is provided with an L-shaped second connecting terminal 32 for connecting the control board 29 to a connector 31. Theconnector 31 is connected to the EPS controller (not shown) via a cable (not shown) .

[0048] [ 0034. ] The housing 6 includes an output-side housing 33 which is formed into a tubular shape whose one end side is open and whose other end side is closed and in which the first and second fluid chambers Pl and P2 are defined, an intermediate housing 34 provided so as to close the one end opening of the output-side housing 33 and accommodating therein the output shaft 10 etc . , and the input-side housing 11 connected to the intermediate housing 34 and accommodating therein the input shaft 7, the connecting shaft 8, a part of the intermediate shaft 9, and the torque sensor 21.

[0049] [ 0035. ] As illustrated in Fig. 1, a power cylinder main body 33a formed along the axial direction of the steering shaft 5, and a shaft portion 33b formed so as to be orthogonal to the power cylinder main body 33a and partly face the power cylinder main body 33a are provided inside the output-side housing 33. The power cylinder main body 33a accommodates therein the piston 18 linked to the output shaft 10, and the first fluid chamber Pl on one end side and the second fluid chamber P2 on the other end side are defined by the piston 18. The shaft portion 33b accommodates therein the sector shaft 3 whose one axial end side is linked to the piston 18 and whose other end side is linked to the steered wheels via the pitman arm (not shown) .[ 0036. ] As described above, the piston 18 and the sector shaft 3 are provided, at their outer peripheral portions, with the rack teeth 18b and the sector gear 3a respectively, which can be engaged with each other . The sector shaft 3 rotates by this engagement between the sector gear 3a and the rack teeth 18b in response to axial movement of the piston 18. Further, the rotation of the sector shaft 3 causes the pitman arm to be pulled in a vehicle width direction, thereby changing a direction of the steered wheels .

[0050] [ 0037. ] As illustrated in Fig. 1, a shaft insertion hole 34a into which the intermediate shaft 9 and the output shaft 10, whose end portions are coaxially arranged, are inserted is formed at an inner peripheral side of the intermediate housing 34. More specifically, the shaft insertion hole 34a is formed into a stepped reduced-diameter shape whose diameter is reduced stepwise along the axial direction from one end side to the other end side . A bearing 35 that rotatably supports the output shaft 10 is provided at a large diameter portion on one end side of the intermediate housing 34. On the other hand, a small diameter portion on the other end side of the intermediate housing 34 is provided with an introduction port 36 that communicates with the pump device (not shown) , a supply / discharge port 37 that supplies and discharges hydraulic pressure (hydraulic fluid) introduced through the introduction port 36 to and from each of the firstand second fluid chambers Pl and P2, and a discharge port 38 that discharges the hydraulic fluid discharged from each of the first and second fluid chambers Pl and P2 via the supply / discharge port 37 to a reservoir tank (not shown) . The supply / discharge port 37 communicates with the first fluid chambers Pl via a first supply / discharge passage LI provided at the one end side enlarged-diameter portion of the output shaft 10, and communicates with the second fluid chambers P2 via a second supply / discharge passage L2 etc . provided at the inside of the output-side housing 33.

[0051] [ 0038. ] The input-side housing 11 is made of a metal material, such as an aluminum alloy material . The input-side housing 11 is formed into a cylindrical tubular shape whose diameter is enlarged stepwise from its one end side toward its other end side . As illustrated in Figs . 1 and 2, the inputside housing 11 has a tubular protruding portion 39a at a portion, which overlaps the rack teeth 18b of the piston 18 in the axial direction of the steering shaft 5, on an outer periphery of an axial end portion 39 on one end side of the input-side housing 11. The tubular protruding portion 39a has a tubular shape that protrudes radially outwards from the outer peripheral portion of the axial end portion 39. The aforementioned connector 31 for connecting the torque sensor 21 and the cable (not shown) is fitted into the tubular protruding portion 39a .[ 0039. ] Furthermore, as depicted in Fig. 2, the input-side housing 11 has a stepped portion 39d at a position, which is close to an opening end surface 39c of the axial end portion 39, on an inner peripheral surface 39b of the axial end portion 39. The stepped portion 39d is formed to be recessed radially outwards from the inner peripheral surface 39b of the axial end portion 39, and has an annular shape that circumferentially continues along the circumferential direction of the steering shaft 5. The aforementioned dust seal 40 as an annular seal member is fixed to the stepped portion 39d. More specifically, the dust seal 40 is fitted into the stepped portion 39d from the inside of the inputside housing 11, and fixed to the stepped portion 39d. The dust seal 40 suppresses entry of dust etc . into the inside of the input-side housing 11 from the outside .

[0052] [ 0040. ] As shown in Fig. 2, an annular space S that circumferentially continues is provided between the outer portion of the input-side housing 11, the input shaft 7, the dust seal 40 and the axial end portion 39.

[0053] [ 0041. ] As illustrated in Figs . 1 and 2, the annular cover member 41 that covers the opening end surface 39c of the axial end portion 39 of the input-side housing 11 is provided at an outer peripheral portion of the input shaft 7 of the steering shaft 5. The cover member 41 is made of synthetic resin. Instead of the synthetic resin, thecover member 41 could be made of rubber . A length of the cover member 41 along the radial direction of the steering shaft 5 is greater than an outside diameter of the axial end portion 39 except the tubular protruding portion 39a . The cover member 41 has an annular base portion 41a, a cylindrical tubular fixing portion 41b extending from an inner edge of the annular base portion 41a to the dust seal 40 side, an annular protruding portion 41c protruding from an outer edge of the annular base portion 41a to the input-side housing 11 side, and an annular first protrusion 41d protruding from a back surface of the cover member 41 to the axial end portion 39 side .

[0054] [ 0042. ] As shown in Fig. 2, an annular protruding rib 41e radially protruding from an inner peripheral surface of the fixing portion 41b toward the input shaft 7 is formed at an axial middle position on the inner peripheral surface of the fixing portion 41b . This protruding rib 41e is fitted into an annular retaining groove 7a formed at the outer peripheral portion of the input shaft 7, thereby fixing the cover member 41 to the input shaft 7. An axial end 41f on the other end side of the fixing portion 41b overlaps the axial end portion 39 of the input-side housing 11 in the radial direction of the steering shaft 5.

[0055] [ 0043. ] As seen in Fig. 2, the protruding portion 41c has a tip surface 41g at the other end side of the protruding portion 41c . The tip surface 41g islocated at one end side with respect to the axial end 41f of the fixing portion 41b . The tip surface 41g overlaps the axial end portion 39 of the inputside housing 11 in the radial direction of the steering shaft 5.

[0056] [ 0044. ] When water, such as rainwater or muddy water, is splashed up by the steered wheels and enters the engine compartment, the first protrusion 41d suppresses entry of this water into the space S through a gap Cl between the cover member 41 and the axial end portion 39 of the input-side housing 11. As another example of the entry of water into the engine compartment, it is a case where water enters the engine compartment during carwash. As seen in Fig. 2, the first protrusion 41d is provided at a position, facing the opening end surface 39c of the axial end portion 39 of the input-side housing 11, on the back surface of the annular base portion 41a of the cover member 41. More specifically, as depicted in Figs . 2, 3A and 3B, the first protrusion 41d is formed at a position, which is close to the protruding portion 41c, on the back surface of the annular base portion 41a of the cover member 41.

[0057] Furthermore, a length of the first protrusion 41d along the axial direction of the steering shaft 5 is shorter than a length of the protruding portion 41c along the axial direction of the steering shaft 5. A gap C2 whose axial width is narrower than that of the gap Cl remains between a tip 41h of the firstprotrusion 41d and the opening end surface 39c of the axial end portion 39.

[0058] [ 0045. ] In the steering device configured as above, when the driver steers the vehicle (turns or operates the steering wheel) , hydraulic fluid pressurized by the pump device is supplied to one of the fluid chamber Pl or P2 via the rotary valve 20 according to a steering direction, and also hydraulic fluid (surplus hydraulic fluid) corresponding to a supply amount of the hydraulic fluid is discharged from the other of the fluid chamber Pl or P2 to the reservoir tank. The piston 18 is then driven by the hydraulic pressure, and an assist torque based on the hydraulic pressure acting on the piston 18 is given to the sector shaft 3.

[0059] [ 0046. ] As described above, the first protrusion 41d is formed at the position, facing the opening end surface 39c of the axial end portion 39 of the input-side housing 11, on the back surface of the annular base portion 41a of the cover member 41. The gap C2 whose axial width is narrower than that of the gap Cl remains between the tip 41h of the first protrusion 41d and the opening end surface 39c of the axial end portion 39. Therefore, when water, such as rainwater or muddy water, is splashed up by the steered wheels, the water strikes an outer peripheral surface of the first protrusion 41d, and is made to fall to an outer peripheral side of the input-side housing 11. Furthermore, if the water is not made to fall to the outer peripheral side of theinput-side housing 11 and attempts to pass through the gap C2, since the gap C2 is narrower, the water does not easily enter the space S of the input-side housing 11. Accordingly, deterioration of the dust seal 40 and / or corrosion of the inner peripheral surface 39b of the axial end portion 39 of the input-side housing 11 due to water are suppressed, and thus water does not reach the torque sensor 21 side . As a result, it is possible to suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0060] [ 0047. ] Fig. 4 is an enlarged local sectional view of a steering device according to a second embodiment .

[0061] [ 0048. ] In the second embodiment, in addition to the first protrusion 41d, the cover member 41 has an annular second protrusion 41i that suppresses entry of water into the space S through the gap Cl between the cover member 41 and the axial end portion 39 of the input-side housing 11.

[0062] [ 0049. ] As seen in Fig. 4, the second protrusion 41i is provided at a position, facing the opening end surface 39c of the axial end portion 39 of the input-side housing 11, on the back surface of the annular base portion 41a of the cover member 41. More specifically, as depicted in Fig. 4, the second protrusion 41i is formed at a position, which is close to the fixing portion 41b, on the back surface of the annular base portion 41a of the cover member41. A length of the second protrusion 41i along the axial direction of the steering shaft 5 is the same as the length of the first protrusion 41d along the axial direction of the steering shaft 5. Similar to the first protrusion 41d, a gap C3 having the same axial width as that of the gap C2 remains between a tip 41 j of the second protrusion 41i and the opening end surface 39c of the axial end portion 39.

[0063] [ 0050. ] Here, in the present embodiment, the cover member 41 has the two protrusions of the first protrusion 41d and the second protrusion 41i .

[0064] However, the cover member 41 may have three or more protrusions at positions facing the opening end surface 39c of the axial end portion 39.

[0065] [ 0051. ] As described above, in the second embodiment, the cover member 41 has the first protrusion 41d and the second protrusion 41i .

[0066] Therefore, if water attempts to enter the space S side beyond the first protrusion 41d, since the gap C3 between the tip 41 j of the second protrusion 41i and the opening end surface 39c of the axial end portion 39 is narrow, the water does not easily enter the space S of the input-side housing 11.

[0067] Thus, as compared with the first embodiment, it is possible to effectively suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0068] [ 0052. ] Fig. 5 is an enlarged local sectional view of a steering device according to a third embodiment .[ 0053. ] In the third embodiment, an axial length of the input-side housing 11 extends to one end side so that the opening end surface 39c of the axial end portion 39 of the input-side housing 11 is located further at one end side as compared with the first embodiment . In addition, in the third embodiment, the first protrusion 41d of the first embodiment is removed, instead, the cover member 41 has a third protrusion 41k whose axial length is longer than that of the first protrusion 41d. Furthermore, axial lengths of the fixing portion 41b and the protruding portion 41c of the cover member 41 are formed to be longer than those of the first embodiment .

[0069] [ 0054. ] As illustrated in Fig. 5, a portion, which is adj acent to the outer periphery of the input-side housing 11, of the opening end surface 39c of the axial end portion 39 of the input-side housing 11 is formed at a position offset to the torque sensor 21 side in the axial direction. In other words, an outer peripheral side opening end surface 39e is formed at the position adj acent to the outer periphery of the input-side housing 11 on the opening end surface 39c, and this outer peripheral side opening end surface 39e is located at the position offset to the torque sensor 21 side as compared with the opening end surface 39c located at the inner peripheral side of the input-side housing 11 .

[0070] [ 0055. ] The third protrusion 41k is formed at a position, facing the outer peripheral side openingend surface 39e, on the back surface of the annular base portion 41a of the cover member 41, and protrudes toward the outer peripheral side opening end surface 39e . More specifically, as depicted in Fig. 5, the third protrusion 41k is formed so as to be located at a position close to a portion M that is adj acent to the opening end surface 39c on the outer periphery of the input-side housing 11, and protrudes toward the vicinity of the outer peripheral side opening end surface 39e from the back surface of the annular base portion 41a of the cover member 41.

[0071] [ 0056. ] A gap is formed between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c and between the back surface of the annular base portion 41a of the cover member 41 and the outer peripheral side opening end surface 39e . A width of the gap in the axial direction of the steering shaft 5 on the steering shaft 5 side is set to be narrower than that on the outer peripheral side of the input-side housing 11. That is, a gap C4 between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c is narrower than a gap C5 between the back surface of the annular base portion 41a of the cover member 41 and the outer peripheral side opening end surface 39e . Similarly, a gap C6 between a tip 41m of the third protrusion 41k and the outer peripheral side opening end surface 39e of the axial end portion 39, and a gapC7 between the portion M of the outer periphery of the input-side housing 11 and an inner surface of the third protrusion 41k are narrower than the gap C5.

[0072] [ 0057. ] As described above, in the third embodiment, the gap C4 between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c is narrower than the gap C5 between the back surface of the annular base portion 41a of the cover member 41 and the outer peripheral side opening end surface 39e . Therefore, even if water enters the gap C5, the water does not easily reach the space S through the narrower gap C4 located on the steering shaft 5 side with respect to the gap C5. It is thus possible to suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21 .

[0073] [ 0058. ] Fig. 6 is an enlarged local sectional view of a steering device according to a fourth embodiment .

[0074] [ 0059. ] In the fourth embodiment, the first protrusion 41d of the first embodiment is removed, instead, the cover member 41 has an annular fourth protrusion 41n whose axial length is longer than that of the fixing portion 41b . This fourth protrusion 41n is formed at a substantially middle position between the fixing portion 41b and the protruding portion 41c on the back surface of theannular base portion 41a of the cover member 41, and protrudes downward.

[0075] [ 0060. ] In addition, an annular groove 42 that is recessed from the opening end surface 39c to the torque sensor 21 side is formed at a radially middle position on the opening end surface 39c of the axial end portion 39. The annular groove 42 continues from the opening end surface 39c of the axial end portion 39 to the vicinity of the stepped portion 39d. A tip 41o side of the fourth protrusion 41n of the cover member 41 is inserted into this annular groove 42, which forms a so-called nest structure . The tip 41o of the fourth protrusion 41n is located close to a bottom surface 42a of the annular groove 42. As shown in Fig. 6, a passage 43 having a U-shape in cross section taken along the axial direction of the steering shaft 5 is formed between the annular groove 42 and the fourth protrusion 41n. A width of this passage 43 is narrower than that of the gap Cl between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c of the axial end portion 39 of the input-side housing 11.

[0076] [ 0061. ] As described above, in the fourth embodiment, the annular groove 42 recessed from the opening end surface 39c to the torque sensor 21 side is formed at the radially middle position on the opening end surface 39c of the axial end portion 39. The tip 41o side of the fourth protrusion 41n of the cover member 41 is inserted into the annular groove42, which forms the nest structure . With this structure, when water enters the gap Cl between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c of the axial end portion 39 of the input-side housing 11 from the outer peripheral side of the input-side housing 11, unless the water passes through the passage 43 formed by the fourth protrusion 41n and the annular groove 42 that form the nest structure while meandering, the water cannot reach the space S . Therefore, since entry of the water into the space S becomes even more difficult, it is possible to further suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0077] [ 0062. ] Fig. 7 is an enlarged local sectional view of a steering device according to a fifth embodiment .

[0078] [ 0063. ] In the fifth embodiment, a portion, located on the inner peripheral side of the input-side housing 11, of the opening end surface 39c of the axial end portion 39 of the fourth embodiment is offset to one end side . In other words, an inner peripheral side opening end surface 39f is formed at a position adj acent to the inner periphery (a portion, located on one end side with respect to the dust seal 40, of the inner peripheral surface 39b of the axial end portion 39) of the input-side housing 11 on the opening end surface 39c, and this inner peripheral side opening end surface 39f is offset toone end side as compared with the opening end surface 39c located at the outer peripheral side of the input-side housing 11. With this structure, a gap C8 between the back surface of the annular base portion 41a of the cover member 41 and the inner peripheral side opening end surface 39f is narrower than the gap Cl between the back surface of the annular base portion 41a of the cover member 41 and the opening end surface 39c of the axial end portion 39 of the input-side housing 11.

[0079] [ 0064. ] As described above, in the fifth embodiment, in addition to the nest structure formed by the fourth protrusion 41n and the annular groove 42 of the fourth embodiment, the gap C8 located on the inner peripheral side of the input-side housing 11 is narrower than the gap Cl located on the outer peripheral side of the input-side housing 11.

[0080] Therefore, if water attempts to enter the space S beyond the nest structure, the water does not easily pass through the gap C8 . It is thus possible to further suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0081] [ 0065. ] Fig. 8 is an enlarged local sectional view of a steering device according to a sixth embodiment .

[0082] [ 0066. ] In the sixth embodiment, the first protrusion 41d of the first embodiment is removed, instead, the cover member 41 has annular fifth to ninth protrusions 41p, 41q, 41r, 41s and 41t . Thefifth to ninth protrusions 41p, 41q, 41r, 41s and 41t are formed at positions, facing the opening end surface 39c of the axial end portion 39 of the input-side housing 11, on the back surface of the annular base portion 41a of the cover member 41, and protrude downward. Each of the fifth to ninth protrusions 41p, 41q, 41r, 41s and 41t is triangular in cross section taken along the axial direction of the steering shaft 5, and is tapered toward the torque sensor 21 side . The fifth to ninth protrusions 41p, 41q, 41r, 41s and 41t are arranged at regular intervals in the radial direction of the steering shaft 5.

[0083] [ 0067. ] As described above, in the sixth embodiment, the fifth to ninth protrusions 41p, 41q, 41r, 41s and 41t are triangular in cross section taken along the axial direction of the steering shaft 5. By providing such fifth to ninth protrusions 41p, 41q, 41r, 41s and 41t, a narrow gap is formed between these protrusions 41p, 41q, 41r, 41s and 41t and the opening end surface 39c of the axial end portion 39 of the input-side housing 11. This narrow gap reduces entry of water into the space S, thereby suppressing failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0084] [ 0068. ] Fig. 9A is a back view of a cover member 41 of a steering device according to a seventh embodiment . Fig. 9B is a cross section of the cover member 41, cut along a line A-A of Fig. 9A.[ 0069. ] In the seventh embodiment, four outer ribs 44 for blocking water and four inner ribs 45 for reinforcement are added to the cover member 41 of the first embodiment .

[0085] [ 0070. ] As illustrated in Fig. 9A, each of the four outer ribs 44 connects the annular first protrusion 41d and the annular protruding portion 41c, and extends along the radial direction of the steering shaft 5. The four outer ribs 44 are arranged at 90-degree regular intervals along a rotational direction R (the circumferential direction) of the steering shaft 5. As shown in Fig. 9B, a length of each outer rib 44 along the axial direction of the steering shaft 5 (along a vertical direction in Fig.

[0086] 9B) is the same as the length of the first protrusion 41d along the axial direction of the steering shaft 5. As shown by arrows in Fig. 9A, although water splashed up by the steered wheels attempts to enter the inner peripheral side of the cover member 41 while moving along the circumferential direction of the cover member 41, the water strikes the outer ribs 44, and is made to fall to the outer peripheral side (see Fig. 2 etc . ) of the input-side housing 11. In an example shown in Fig. 9A, the two outer ribs 44 are arranged so as to define a 90-degree region in the circumferential direction of the cover member 41, and the water strikes these two outer ribs 44. Therefore, if water attempts to enter the space S (see Fig. 2 etc . ) , the water stays or is stored within one-quarter range(one-quarter region) of the outer periphery of the cover member 41. If the four outer ribs 44 are not formed on the cover member 41, water may reach the inner peripheral side of the input-side housing 11 while moving along the entire outer periphery of the input-side housing 11.

[0087] [ 0071. ] As for the four inner ribs 45, as shown in Fig. 9A, each of the four inner ribs 45 connects the annular first protrusion 41d and the annular fixing portion 41b, and extends along the radial direction of the steering shaft 5. The four inner ribs 45 are arranged at 90-degree regular intervals along the rotational direction R of the steering shaft 5. More specifically, the four inner ribs 45 are arranged at positions shifted by 45 degrees from the respective adj acent outer ribs 44 in the circumferential direction of the cover member 41. As shown in Fig.

[0088] 9B, a length of each inner rib 45 along the axial direction of the steering shaft 5 is the same as the length of the first protrusion 41d along the axial direction of the steering shaft 5. The inner ribs 45 function as reinforcing portions to suppress deformation of the cover member 41 when water strikes the outer peripheral surface of the first protrusion 41d after moving along the circumferential direction of the cover member 41 and striking the outer ribs 44.

[0089] [ 0072. ] As described above, in the seventh embodiment, the protruding portion 41c and the first protrusion 41d are connected by the outer ribs 44extending in the radial direction of the steering shaft 5, and water moving along the circumferential direction of the cover member 41 is blocked by the outer ribs 44. Therefore, water does not easily reach the space S . It is thus possible to suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0090] [ 0073. ] Fig. 10 is an enlarged local sectional view of a steering device according to an eighth embodiment .

[0091] [ 0074. ] In the eighth embodiment, a groove 46 as a drain is formed on the opening end surface 39c of the axial end portion 39 of the input-side housing 11 of the first embodiment . This groove 46 discharges water stored in the space S to the outside of the input-side housing 11. The groove 46 is formed by die-cutting during the casting process of the metal input-side housing 11. As illustrated in Fig. 10, the groove 46 is formed on an opposite side to the tubular protruding portion 39a on the opening end surface 39c of the axial end portion 39 of the input-side housing 11. More specifically, the groove 46 is formed at the farthest position from the tubular protruding portion 39a on the opening end surface 39c of the axial end portion 39 of the input-side housing 11. Here, in the present embodiment, the single groove 46 is formed on the opposite side to the tubular protruding portion 39a on the opening end surface 39c of the axial endportion 39 of the input-side housing 11. However, a plurality of grooves 46 may be formed.

[0092] [ 0075. ] The groove 46 is a groove that continues or extends along the radial direction of the steering shaft 5. That is, the groove 46 is a groove that is recessed from the opening end surface 39c of the axial end portion 39 to the other end side in the axial direction of the steering shaft 5, and that extends from the outside portion of the input-side housing 11 toward the axial center of the steering shaft 5 with a fixed groove width. It is noted that, instead of the fixed groove width, the groove 46 may extend with unfixed groove width. For instance, the groove 46 may be formed into a shape whose groove width is tapered toward the radially outer side of the steering shaft 5, or the groove 46 may be formed into a shape whose groove width is tapered toward the radially inner side of the steering shaft 5. A depth of the groove 46 is set to a depth from the opening end surface 39c of the axial end portion 39 to the vicinity of the stepped portion 39d. It is desired that the depth of the groove 46 be set to be as deep as possible within a range where sufficient rigidity of the stepped portion 39d can be ensured to retain the dust seal 40.

[0093] [ 0076. ] Furthermore, instead of the groove 46 as the drain formed on the opening end surface 39c of the axial end portion 39, a through hole could be formed to penetrate the axial end portion 39 along the radial direction of the steering shaft 5.[ 0077. ] As described above, in the eighth embodiment, the groove 46 as the drain is formed on the opening end surface 39c of the axial end portion 39 of the input-side housing 11. Therefore, water stored in the space S is discharged to the outside of the input-side housing 11 via the groove 46. It is thus possible to avoid deterioration of the dust seal 40 and / or corrosion of the inner peripheral portion of the input-side housing 11, and suppress failure of various electronic components, such as the magnetic sensor 27 etc . , that constitute the torque sensor 21.

[0094] DESCRIPTION OF REFERENCE SYMBOLS

[0095] [ 0078 . ]

[0096] 5 ••• steering shaft

[0097] 11 ••• input-side housing

[0098] 21 ••• torque sensor

[0099] 39 ••• axial end portion

[0100] 39c ••• opening end surface

[0101] 40 ••• dust seal

[0102] 41 ••• cover member

[0103] 41d ••• first protrusion

[0104] 41i ••• second protrusion

[0105] 41k ••• third protrusion

[0106] 41n ••• fourth protrusion41p ••• fifth protrusion 41q ••• sixth protrusion 41r ••• seventh protrusion 41s ••• eighth protrusion 41t ••• ninth protrusion 42 ••• annular groove

[0107] 44 ••• outer rib

[0108] 45 ••• inner rib

[0109] 45 ••• groove

Claims

- 35 -CLAIMS

1. A steering device comprising:a steering shaft structured to input a rotational force from a steering wheel;a transmission mechanism configured to transmit the rotational force of the steering shaft to steered wheels;a torque sensor provided at a periphery of the steering shaft and detecting a steering torque of the steering shaft;a housing having an opening surface through which the steering shaft passes and accommodating a part of the steering shaft, the housing provided, on an inner peripheral surface of an axial end portion located on a side of the opening surface of the housing, with a stepped portion whose diameter is enlarged stepwise toward an opposite side to the steering wheel in an axial direction of the steering shaft;an annular seal member provided at the stepped portion and sealing a gap between the inner peripheral surface of the housing and an outer peripheral surface of the steering shaft; andan annular cover member provided on an outer periphery of the steering shaft and covering an opening end surface of the housing, the cover member provided, at a portion facing the opening end surface of the housing on a back surface of the cover member, with at least one annular- 36 -protrusion protruding toward the opening end surface .

2. The steering device as claimed in claim 1, whereina portion, which is adj acent to an outer periphery of the housing, of the opening end surface of the housing is formed at a position offset to a side of the torque sensor in the axial direction of the steering shaft, anda gap is formed between the back surface of the cover member and the opening end surface of the housing, and a width, in the axial direction of the steering shaft, of the gap located on a side of the steering shaft is set to be narrower than that on a side of the outer periphery of the housing.

3. The steering device as claimed in claim 1, whereinan annular groove into which the protrusion is inserted is formed on the opening end surface of the housing.

4. The steering device as claimed in claim 1, whereinthe protrusion is triangular in cross section taken along the axial direction of the steering shaft .

5. The steering device as claimed in claim 1, whereinthe cover member has an annular protruding portion protruding from an outer peripheral portion of the cover member toward the torque sensor, and the protruding portion and the protrusion are connected to each other through a rib extending in a radial direction of the steering shaft .

6. The steering device as claimed in any one of the preceding claims 1 to 5, whereina space is formed between the steering shaft, the axial end portion adj acent to the opening end surface of the housing, and the seal member, and the housing is provided, at a portion, positioned on a side of the steering wheel with respect to the seal member, of the axial end portion of the housing, with a drain that connects the space and an outside of the housing and that can discharge water stored in the space .

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