US 7,243,569 B2Granted

Power transmission device, electric power steering device, and method of producing the same

AssigneeKabaya Industry Co., Ltd.

InventorsMasashi Takahashi, Nobuharu Naruse

Life of this patent

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Abstract

In order to achieve low cost, small size, and light weight, to improve response at the time of transmission of power, and to prevent the occurrence of unusual noise, a power transmission device (10) of an electric power steering device (1) has a motor section (5) comprising a rotational shaft (7), a rotor (51) attached to an inner end side (7a) of the rotational shaft (7), and a stator (52) positioned opposite to the rotor (51), a worm gear (61) attached to a distal end side (7b) from the motor section (5) on the rotational shaft (7), and a worm wheel gear (62) engaged with the gear (61). The rotational shaft (7) is rotatably supported by first and second bearings (81, 82), the first bearing (81) being held by a housing (4) at a distal end side (7b) to the worm gear (61). The second bearing (82) is held by the housing (4) between the worm gear (61) and the rotor (51) so that the worm gear (61) is sandwiched between the first and second bearings (81, 82).

Claims11

Dependent claims

A power transmission device, comprising:

a motor section having a rotational shaft, a rotor attached to an inner end side of the rotational shaft, and a stator positioned opposite to the rotor;
a driving gear attached to a distal end side of the rotational shaft with respect to the motor section;
a driven gear engaged with the driving gear;
and
a fixed-side member for rotatably supporting the driven gear, wherein the rotational shaft is a single member and is rotatably supported by a first bearing and a second bearing,
the first bearing is held by the fixed-side member at a distal end side of the rotational shaft with respect to the driving gear, and
the second bearing is held by the fixed-side member between the driving gear and the rotor so that the driving gear is sandwiched between the first bearing and the second bearing, wherein
the motor section has a brushless motor structure comprising a rotation detecting device for detecting rotation of the rotational shaft provided at a distal end side of the rotational shaft with respect to the first bearing.
the rotation detecting device has a movable member mounted on the distal end side of the rotational shaft with respect to the first bearing, and a detector for detecting rotation of the movable member mounted on the fixed-side member.
the fixed-side member is formed with a cylindrical part having a first opening on a first end, and a second opening on a second end,
the first opening of the cylindrical part is configured to accept the first bearing and the rotation detecting device, and
the second opening of the cylindrical part is configured to accept the distal end side portion of the rotational shaft and the second bearing.

9 more elements

A method of manufacturing a power transmission device, the power transmission device comprising:

a motor section having a rotational shaft, a rotor attached to an inner end side of the rotational shaft, and a stator positioned opposite to the rotor,
a driving gear attached to a distal end side of the rotational shaft with respect to the motor section,
a driven gear engaged with the driving gear, and
a fixed-side member for rotatably supporting the driven gear, wherein
the rotational shaft is a single member and is rotatably supported by a first bearing and a second bearing,
the first bearing is held by the fixed-side member at a distal end side of the rotational shaft with respect to the driving gear, and
the second bearing is held by the fixed-side member between the driving gear and the rotor so that the driving gear is sandwiched between the first bearing and the second bearing, and
the fixed-side member is formed with a cylindrical part having a first opening on a first end, and a second opening on a second end.
the method comprising:
a step of assembling the first bearing into the cylindrical part of the fixed-side member from the first opening,
a rotational shaft assembling step of mounting the driving gear and the second bearing on the rotational shaft, and assembling the rotational shaft into the cylindrical part from the second opening so that the drive gear on the rotational shaft is engaged with the driven gear held by the fixed-side member, and the rotational shaft is supported at its distal end side by the fixed-side member via the first bearing and is supported at its inner end side by the fixed-side member via the second bearing.
an engagement inspecting step of inspecting engagement between the driving gear and the driven gear.
a rotor assembling step of attaching the rotor to an inner end side of the rotational shaft, and
a stator assembling step of attaching the stator to the fixed-side member opposite to the rotor so as to constitute the motor section.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/469,397Filed 30 Sep 2002
Priority: JP 2001-3066562 Oct 2001
Published: US 2004/0065163 A18 Apr 2004
Granted: 17 Jul 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

B62D 5/0403
Electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear: characterised by constructional features, e.g.…
B62D 5/0409
Electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear: electric motor acting on the steering column
B62D 15/0235
Determination of steering angle: by measuring or deriving directly at the electric power steering motor
H02K 7/081
Structural association with bearings: specially adapted for worm gear drives