Steering device

A back cover includes an opening configured to penetrate the back cover throughout between an exterior surface and an interior surface of the back cover, lock receivers capable of engaging respectively with hook-shaped lock portions of a switch unit, and fastening portions capable of fastening the switch unit to the back cover. The lock receivers and the fastening portions are arranged near a peripheral edge of the opening at positions with the opening interposed between the lock receivers and the fastening portions.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-109522, filed on May 24, 2013, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a steering device used in vehicles such as automobiles, aircrafts, ships, and railroad vehicles.

2. Related Art

Japanese Patent Application Publication No. Hei 06-270816 describes a related steering device. In the steering device, a switch unit is fixed to the steering device by fastening an attachment member of the switch unit and attachment brackets protruding from a base plate of an airbag module together with bolts screwed into nuts from outside

SUMMARY

In the aforementioned related steering device, the nuts and the bolts are used in work of attaching the switching unit to the base plate of the airbag module, and the switch unit may be misaligned with respect to the base plate due to fastening torque of the bolts. In order to prevent such misalignment of the switch unit, the attachment work needs careful attention paid by a worker and accordingly may require many man hours. Moreover, attachment strength of the switch unit may be so weak that the attachment member may bend in a switch operation direction of the switch unit, for example. Furthermore, since the switch unit is supported only by the attachment member in a cantilever fashion, the switch unit may resonate due to travelling vibrations or the like of a vehicle.

An object of the present invention is to provide a steering device which enables a switch unit to be attached in fewer man hours with a high accuracy and which can increase attachment strength of the switch unit so much that no resonance will occur due to travelling vibrations or the like of a vehicle.

A steering device in accordance with some embodiments includes a boss supportable by a steering shaft, a spoke supported by the boss, a rim supported by the boss via the spoke, a front cover covering an upper portion of the boss, a back cover covering a back surface of the front cover and a periphery of the boss, and a switch unit supported by an exterior side of the back cover and including hook-shaped lock portions. The back cover includes an opening configured to penetrate the back cover throughout between an exterior surface and an interior surface of the back cover, lock receivers capable of engaging respectively with the lock portions, and fastening portions capable of fastening the switch unit to the back cover. The lock receivers and the fastening portions are arranged near a peripheral edge of the opening at positions with the opening interposed between the lock receivers and the fastening portions.

In the configuration described above, the switch unit is placed to penetrate the opening of the back cover throughout when viewed in any of directions from the exterior side and the interior side of the back cover, and the lock receivers and the fastening portions are located at the positions with the opening interposed between the lock receivers and the fastening portions. Hence, the switch unit supported by the lock receivers and the fastening portions acts as a beam for the back cover. With this structure, the switch unit is firmly fixed to the back cover, and the opening determines the attachment position of the switch unit. Thus, the switch unit can be attached to the back cover in fewer man hours with a high accuracy. Moreover, the lock portions can distribute a load applied in an operation of the switch unit, to the back cover via the lock receivers. This increases the attachment strength of the switch unit so much that the switch unit is less likely to resonate due to travelling vibrations or the like of a vehicle.

The back cover may include a reinforcement rib on the interior surface of the back cover around the opening.

In the configuration described above, the reinforcement rib is formed on the interior surface of the back cover around the opening. Accordingly, collapsing of the back cover to which the switch unit is attached can be surely prevented.

The back cover may include a portion which the reinforcement rib is provided on and has a substantially uniform plate thickness.

In the configuration described above, the portion of back cover around the opening has the substantially uniform plate thickness. Accordingly, force applied to the back cover is distributed and wave-like deformation is less likely to occur in the back cover.

The reinforcement rib may include a distal end positioned substantially at a same height as a part of the interior surface of the back cover around an attachment position of the switch unit.

In the configuration described above, the distal end of the reinforcement rib is formed substantially at the same height as the part of the interior surface of the back cover around the attachment position of the switch unit. Accordingly, when the front cover is attached to the steering device after the switch unit is fixed to the back cover, various members provided in the front cover do not interfere with the reinforcement rib and workability of attachment is greatly improved.

DETAILED DESCRIPTION

An embodiment of the present invention is described below in detail on the basis of the drawings. A steering device in accordance with some embodiments includes a boss supportable by a steering shaft, a spoke supported by the boss, a rim supported by the boss via the spoke, a front cover covering an upper portion of the boss, a back cover covering a back surface of the front cover and a periphery of the boss, and a switch unit supported by an exterior side of the back cover and including hook-shaped lock portions. The back cover includes an opening configured to penetrate the back cover throughout between an exterior surface and an interior surface of the back cover, lock receivers capable of engaging respectively with the lock portions, and fastening portions capable of fastening the switch unit to the back cover. The lock receivers and the fastening portions are arranged near a peripheral edge of the opening at positions with the opening interposed between the lock receivers and the fastening portions. The configuration described above enables attachment of the switch unit to the back cover in fewer man hours with a high accuracy. Moreover, the configuration increases attachment strength of the switch unit and makes the switch unit less likely to resonate due to travelling vibrations or the like of a vehicle.

A steering device1in the embodiment of the present invention is described by usingFIGS. 1 to 5. In the embodiment, the steering device1is described as a steering device for an automobile but is not limited to this. The steering device1includes a boss20supportable by a steering shaft21, a spokes4formed by casting magnesium around the boss20, a wheel-shaped rim2supported by the boss20via the spokes4, a synthetic resin front cover3covering an upper portion of the boss20and including therein an airbag main body (not illustrated in the drawings), a synthetic resin back cover6covering a back surface (a lower side inFIG. 1) of the front cover3and a periphery of the boss20, a switch unit5supported by an exterior surface6awhich is an exterior side of the back cover6, and spoke cover portions4aformed continuously with the back cover6. In addition to the members described above, the steering device1may include various devices such as a horn switch, a telephone, a navigator, and an integrated warning device.

The switch unit5includes a button portion5awhich can be pressed in a downward direction inFIG. 3, a switch main body5b, and hook-shaped lock portions11. In the back cover6, an opening7, lock receivers10and fastening portions8,8are formed. The opening7has a rectangular shape elongated in an up-down direction and penetrates the back cover6throughout between the exterior surface6aand an interior surface6bof the back cover6such that the switch main body5bcan be inserted therethrough. The lock receivers10can engage with the lock portions11, and the fastening portions8,8are portions to which the switch main body5bcan be fastened. The lock receivers10and the fastening portions8are arranged near a peripheral edge of the opening7at positions with the opening7interposed between the lock receivers10and the fastening portions8. A lower end portion7aof the opening7comes in close contact with a connection portion main body15of the switch main body5bwhich will be described later. The fastening portions8,8are formed in columnar shapes to protrude from the exterior surface6aof the back cover6. Turn stoppers9,9are formed in ledge shapes below the fastening portions8,8, respectively. Bottom portions12,12of the switch main body5bare placed on the turn stoppers9, respectively. The switch unit5can be temporarily fixed by engaging an engagement hole portion13of the switch main body5bto one of engagement protrusions9aformed to protrude respectively from lower portions of the turn stoppers9.

Each of the lock receivers10includes protrusions10a,10awhich penetrate through the exterior surface6aand the interior surface6bto protrude to the exterior surface6aside, and a gap portion10bwhich is formed between the protrusions10a,10a. As shown inFIG. 5, a T-shaped gap is formed by the protrusions10a,10aand the gap portion10b. Each of the lock portions11has a T-shaped cross section which is formed of a portion configured to ride on the protrusions10a,10aand a rib11aconfigured to be inserted into the gap portion10b. This shape increases the strength of the lock portions11. When the switch unit5is fastened to the fastening portions8,8with screws, turning of the hook-shaped lock portions11is restricted by the protrusions10aand the gap portions10bof the lock receivers10and turning of the switch unit5is thus stopped. Moreover, since the pair of the fastening portions8,8and the pair of the lock receivers10,10are spaced away from each other in the up-down direction and the fastening portions8,8and the lock receivers10,10are arranged such that the opening7interposed between the fastening portions8,8and between the lock receivers10,10, a turn stopping effect in the fastening of the switch unit5to the fastening portions8,8is improved.

Linear reinforcement ribs14,14are formed on the interior surface6bof the back cover6at neighboring portions on both sides of the opening7. Attachment surface portions6c,6d,6eof the back cover6on which the reinforcement ribs14,14are provided have a substantially uniform plate thickness. In detail, the attachment surface portion6cis formed to protrude to the interior surface6bside, the attachment surface portion6eis formed to protrude to the exterior surface6aside, and the attachment surface portion6dis formed to be flush with the exterior surface6a. The connection portion main body15of the switch main body5bhas a function of a connector for connection with a not-illustrated airbag inflator.

Distal ends of the reinforcement ribs14,14are formed substantially at the same height as a part of the interior surface6bof the back cover6around an attachment position of the switch main body5b. Moreover, as shown inFIG. 2, a rib16is provided to stand upright between the interior surface6band a bottom surface6fof the back cover6.

As described above, the steering device1of the embodiment includes at least the boss20supportable by the steering shaft21, the rim2supported by the boss20via the spokes4, the front cover3covering the upper portion of the boss20, the back cover6covering the back surface of the front cover3and the periphery of the boss20, and the switch unit5supported on the exterior surface6aof the back cover6. In the back cover6, there are formed the opening7which penetrates the back cover6throughout between the exterior surface6aand the interior surface6b, the lock receivers10which can engage with the hook-shaped lock portions11in the switch unit5, and the fastening portions8to which the switch main body5bof the switch unit5can be fastened. The lock receivers10and the fastening portions8are arranged near the peripheral edge of the opening7at the positions with the opening7interposed between the lock receivers10and the fastening portions8. In this structure, the switch unit5is placed to penetrate the opening7of the back cover6throughout when viewed in any of directions from the exterior side and the interior side of the back cover6, and the lock receivers10and the fastening portions8are located at the positions with the opening7interposed therebetween. Hence, the switch main body5bof the switch unit5supported by the lock receivers10and the fastening portions8acts as a beam for the back cover6. With this structure, the switch unit5is firmly fixed to the back cover6, and the opening7determines the attachment position of the switch unit5. Thus, the switch unit5can be attached to the back cover6in fewer man hours with a high accuracy. Moreover, the lock portions11can distribute a load F applied in an operation of the switch unit5, to the back cover6via the lock receivers10. This increases the attachment strength of the switch unit5so much that the switch unit5will be less likely to resonate due to travelling vibrations or the like of a vehicle.

The reinforcement ribs14,14are formed on the interior surface6bof the back cover6around the opening7. Accordingly, collapsing of the back cover6to which the switch unit5is attached can be surely prevented.

The back cover6around the opening7is formed to have a substantially uniform plate thickness. Accordingly, force applied to the back cover6such as the load F generated in the operation of the switch unit5is distributed and wave-like deformation is less likely to occur in the back cover6.

The distal ends of the reinforcement ribs14,14are formed substantially at the same height as the part of the interior surface6bof the back cover6around the attachment position of the switch main body5b. Accordingly, when the front cover3is attached to the steering device1after the switch main body5bis fixed to the back cover6, various members provided in the front cover3do not interfere with the reinforcement ribs14,14and workability of attachment is greatly improved.

In the embodiment, the steering device1is described by giving an example in which the steering device1is used in an automobile. However, the steering device1is not limited to this example and may be used in vehicles such as aircrafts, ships, and railroad vehicles. Moreover, in the case of casting the spokes4, the spokes4may be molded by casting magnesium.

In the embodiment, the opening7provided in the back cover6is described as an opening through which the switch main body5bcan be inserted. However, the present invention is not limited to this configuration. For example, a not-illustrated connector member for connection may be arranged on the interior side of the back cover6, be inserted through the opening7in the back cover6, and be connected to the switch unit5.

Although the embodiments of the present invention has been described above, the invention is not limited to the above embodiment, and various modifications are possible.