For example, a motor having a clutch recited in Patent Literature 1 is known as a prior art motor. The motor having the clutch recited in Patent Literature 1 is used as, for example, a drive apparatus for opening and closing a louver of an air conditioner, a drive apparatus of an automatic valve, or a drive apparatus of various rotatable devices, such as a turn table of a microwave oven. The motor having the clutch recited in Patent Literature 1 has speed reducing gears, which include gears meshes with a rotor gear of the motor, and an output shaft, which is driven by a final stage gear among the speed reducing gears.
The output shaft has a pin, which is made of metal, and a synthetic resin portion, which is placed around the pin and is made of resin having flexibility. In the output shaft, one end side of the pin is supported by an intermediate cover of a casing, and an axial intermediate part of the synthetic resin portion is supported by the housing of the motor and is rotatable. Furthermore, a gear part is formed at an outer peripheral part of one axial end side of the synthetic resin portion. A space is formed between the gear part and a support shaft part, which is formed as a wall part of the synthetic resin portion at the outer peripheral part of the pin. This space is opened at the one axial end side of the synthetic resin portion, in which the gear part is formed, and this space extends toward the opposite axial side beyond a supported point of the synthetic resin portion, which is supported by the housing of the motor.
In this type of motor having the clutch, when an excess torque is applied to the gear part, the gear part is deformed toward an inner side of the space, and thereby slipping may occur between the gear part and a gear, which is meshed with the gear part.
However, in Patent Literature 1, the space is formed in the output shaft in such a manner that the space extends in the axial direction beyond the supported point, which is supported by the housing of the motor, in order to implement the clutch function. Therefore, in a case where the motor is used to drive a reflector of the vehicle head-up display apparatus, a weight load of the reflector, vehicle vibrations generated at the time of driving the vehicle, or a shock load generated at the time of opening or closing a door is applied to the output shaft. Thereby, there is a disadvantage of that a large stress is generated at the supported part of the output shaft to result in breakage of the output shaft.
USPTO Backgrounds
USPTO Backgrounds