Meter unit including step motor and braking spring
View Patent ↗A meter unit includes a step motor, a gear, a braking spring and a case. The gear has a gear body and a rotation shaft. The braking spring urges the gear in a direction of an axis of rotation of the gear. The case accommodates the step motor, the gear body, a part of the rotation shaft, and the braking spring therein. The braking spring has a shape through which the first part of the rotation shaft passes. A first face of the gear body is formed with a recessed portion which accommodates the braking spring. A first part of the case supports a second face of the gear body. A second part of the case is configured to press the braking spring so that entire part of the braking spring is accommodated in the recessed portion.
1. A meter unit, comprising:
a step motor;
a gear having:
a gear body, configured to be rotated by a torque transmitted from the step motor, and having a first face and a second face opposite to the first face; and
a rotation shaft including a first part extended from the first face and a second part extended from the second face;
a braking spring configured to urge the gear in a direction of an axis of rotation of the gear; and
a case accommodating the step motor, the gear body, a part of the rotation shaft, and the braking spring therein, wherein
the braking spring has a shape through which the first part of the rotation shaft passes,
the first face is formed with a recessed portion which accommodates the braking spring,
a first part of the case supports the second face of the gear body, and a second part of the case is configured to press the braking spring so that a height of the braking spring is smaller than a depth of the recessed portion,
the braking spring has an annular shape having a hole through which the rotation shaft passes,
the second part of the case protrudes from an inner face of the case to the braking spring and comes in contact with the braking spring at an end part thereof, and
a portion of the second part of the case protrudes into the recessed portion of the first face of the gear body,
wherein a portion of the second part of the case and the braking sprit are recessed in the recessed portion.
2. The meter unit according to claim 1 , wherein
the braking spring is a leaf spring,
a periphery of the leaf spring has a circular shape, and
the recessed portion surrounds the rotation shaft and is recessed corresponding to the periphery of the leaf spring.
3. The meter unit according to claim 1 , further comprising:
a stopper, protruding from the inner face of the case toward the first face of the gear body, wherein
an end face of the stopper is configured to come in contact with the first face of the gear body so as to prevent the rotation shaft from being pulled out when a pointer attached to an end part of the first part of the rotation shaft is pulled out,
the end face of the stopper is provided at a distance from the end part of the second part of the case in a direction separating from the gear body, and
a distance between the end face of the stopper and the end part of the second part of the case is smaller than a distance between the second part of the case and a bottom face of the recessed portion.
4. The meter unit according to claim 1 , wherein
the first part of the case is a bearing which supports the second part of the rotation shaft, and
the second part of the case is a shaft hole which supports the first part of the rotation shaft.
5. The meter unit according to claim 1 , wherein
the protruded part of the second part of the case has a cylindrical form with an opening formed at a side of the gear.
6. The meter unit according to claim 1 , wherein a portion of the second part of the case is recessed in the recessed portion at a distance from a surface of the recessed portion, with the braking spring disposed between the surface of the recessed portion and the second part of the case.