The starter of the gear reducer between the armature axis of the starter and the drive gear is called a deceleration starter. Series excitation type DC motor power and torque and speed is proportional to, when visible, while improving the motor speed and reduce the torque when the starter power can keep unchanged, so when the series excited DC motor with high speed and low torque as the starter, the same power, can make the volume and quality of the starter greatly reduced.
However, the torque of the starter is too low to meet the requirements of the starting engine. To this end, when the DC motor with high speed and low torque is used in the starter, the gear reducer between the armature shaft and the driving gear of the motor is installed, which can reduce the speed of the motor while improving the torque.
Classification of deceleration starter
The gear reducer of decelerating starter has three different forms, such as outer meshing, internal meshing and planetary gear.
Outer meshing deceleration starter
The deceleration mechanism uses the idler wheel as the intermediate drive between armature shaft and starter drive gear, and the core of the electromagnetic switch and the drive gear directly drive the drive gear to mesh, without shifting fork. Therefore, the shape of the starter is quite different from that of the common starter.
There are usually indolent gear reducer and external meshing deceleration starter without idler. The outer drive type deceleration mechanism has larger transmission center distance. Therefore, the speed reduction ratio can't be too large due to the limitation of starting mechanism. Generally, it is not more than 5, and it is mostly used on low power starter.
Internal meshing deceleration starter
The drive center of the deceleration mechanism is small and can have a larger deceleration ratio, so it is suitable for high power starter. But the noise of the internal meshing deceleration mechanism is large, and the driving gear still needs to dial the fork to move into the meshing. Therefore, the shape of the starter is similar to that of the common starter.
Planetary gear reducer
The deceleration mechanism is compact in structure, large in transmission ratio and high in efficiency. As the axis of the output axis and the axis of the axis, the same axis, the armature axis has no radial load, the vibration is light, and the size of the whole machine is reduced. In addition, the planetary gear reducer also has the following advantages:
(1) the load is evenly distributed on three planetary gears, which can be made of plastic inner gear and powder metallurgy planetary gear, so as to reduce the quality and reduce the noise.
(2) although the planetary gear reducer is added, the axial other structure of the starter is the same as that of the ordinary starter, so the accessories can be used.
Therefore, planetary gear deceleration starter is applied more and more widely. TOYOTA series cars and some Audi cars also use planetary gear decelerating starter.