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AssigneeKoyo Seiko Co., Ltd.
InventorsYoshitomo Tokumoto, Naoki Maeda, Mahito Shiba
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A rotational angle detecting apparatus wherein one or more first targets 3a are provided on a steering shaft 13 so that first detecting means 1A outputs a detection signal as the steering shaft 13 rotates, second detecting means 1B outputs a detection signal having a phase different from that of the detection signal of the first detecting means 1A, and the rotational angle of the steering shaft 13 is detected on the basis of the detection signals outputted by the first detecting means IA and the second detecting means 1B. A rotational angle detecting apparatus further comprising second targets 3b, the number of which is prime to the number of the first targets 3a, provided on the steering shaft 13, third detecting means 3A, disposed opposite to the second targets 3b, for outputting a detection signal as the steering shaft 13 rotates, and fourth detecting means 3B for outputting a detection signal having a phase different from that of the detection signal of the third detecting means 3A, wherein the rotational angle of the steering shaft 13 is detected on the basis of the detection signals outputted by the first to fourth detecting means 1A, 1B, 3A and 3B, thereby being capable of detecting an absolute rotational angle.
A rotational angle detecting apparatus comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
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With incremental and absolute tracks on the same encoder: incremental encoders having reference marks
Steering not otherwise provided for: steering position indicators ; Steering position determination; Steering aids
Incremental encoders: incorporating two or more tracks having an relationship
Involving magnetic or electromagnetic means: involving permanent magnets
Term end not estimated
1. Field of the Invention
The present invention relates mainly to an automobile steering apparatus including a power steering apparatus using an electric motor and to a rotational angle detecting apparatus and a torque detecting apparatus therefor.
More particularly, the present invention relates to a rotational angle detecting apparatus wherein one or more targets are provided on a rotating member so that first detecting means outputs a detection signal as the rotating member rotates, second detecting means outputs a detection signal having a phase different from that of the detection signal of the first detecting means, and the rotational angle of the rotating member is detected on the basis of the detection signals outputted by the first detecting means and the second detecting means, to a torque detecting apparatus for detecting torque applied to a first shaft depending on a torsional angle generating in a connecting shaft for connecting the first shaft and a second shaft, and to a steering apparatus for generating a steering-assisting force on the basis of the detection result of the torque detecting apparatus.
FIG. 1 is a schematic view showing the configurations of a rotational angle detecting apparatus, a torque detecting apparatus and a steering apparatus in accordance with an embodiment of the present invention;
FIG. 2A, FIG. 2B and FIG. 2C are waveforms showing examples of the detection signals of magnetic sensors;
FIG. 3 is a waveform showing examples of the detection signals of magnetic sensors, the number of targets disposed opposite to one magnetic sensor being different from the number of targets disposed opposite to the other magnetic sensor;
The present invention will be described below referring to the accompanying drawings showing embodiments thereof.
FIG. 1 is a schematic view showing the configurations of a rotational angle detecting apparatus, a torque detecting apparatus and a steering apparatus in accordance with an embodiment of the present invention, mainly applied to automobiles, for example. In this steering apparatus, an input shaft 16 (a rotating member functioning as a first shaft) whose upper end portion is connected to a steering wheel 1 (a steering member) is coaxially connected to an output shaft 17 (a rotating member functioning as a second shaft) whose lower end portion is connected to a pinion 18 in a steering mechanism (not shown) via a torsion bar 19 (a connecting shaft) having a small diameter, whereby a steering shaft 13 for connecting the steering wheel 1 to the steering mechanism is formed. The configuration in the vicinity of the connecting portion between the input shaft 16 and the output shaft 17 is described below.
In the vicinity of an end portion of the connecting side of the input shaft 16 connected to the output shaft 17, disc-shaped target plates 12a and 12b are coaxially fitted on the input shaft 16 and secured thereto with the target plate 12a (a rotating member) disposed on the side of the steering wheel 1. On the outer circumferential face of the target plate 12a, a plurality of targets 3a (first targets), which are convex portions made of a magnetic material, 36 pieces for example, are provided at equal intervals so as to protrude in the circumferential direction. On the outer circumferential face of the target plate 12b (another rotating member), a plurality of targets 3b (second targets), which are convex portions made of a magnetic material, are provided at equal intervals so as to protrude in the circumferential direction. The number of the targets 3b is for example 37, a number being prime to the number of the targets 3a. The fact that two numbers are prime to each other means that they do not have any common divisors other than one.