Automotive Product StudiesStarter Motor Teardown and Feature Study

Starter-Motor Cross Section View

Starter Motor Teardown and Feature Study

Disclaimer

This study was conducted entirely in-house by ASI Engineering to demonstrate the capabilities of the xcPEP® platform. The product was independently procured by ASI. No proprietary or confidential information from any other party has been used. Results are not updated after publishing.

Recently we conducted VA/VE exercise on the starter motor used for commercial vehicle application. We at Advanced Structures India use Engineering Intelligence and xcPEP to map data which includes material information, architecture and layout study, manufacturing process and complexity data.

This blog contains our findings on starter motor consisting of:

  1. Introduction to starter motor and its types.
  2. Features and specifications mapped in starter motor.
  3. Bill of materials generated from xcPEP.
  4. Architecture and layout study of starter motor.

Introduction to starter motor and its types

Starter motor: A starter motor is an electric motor designed to initiate the operation of an internal combustion engine. The pinion gear meshes with the flywheel and rotates it when the key is turned ON and disengages when the engine starts to run by itself. Different types of starter motors used:
Types based on Gear reduction methods:
  1. Direct Drive Electric Starter Motor
  2. Gear Reduction Type Starter Motor
Types based on armature:
  1. Permanent Magnet armature type
  2. Field Coil armature type

The motor considered in this activity is of gear reduction type where planetary gear set is used for torque multiplication since the size of the flywheel is large and higher torque is required to rotate it.

The starter motor used for study is observed to be a permanent magnet armature type as it is provided with permanent magnets which acts as a stator and rotates the rotor made up of electromagnets.

Starter-Motor gear
Starter-Motor Outer case
Starter-Motor Cross Section View
Features mapped in starter motor

Features are mapped using xcPEP tool.

The features are divided into two categories:

  • Product level features.
  • Part level features.

Product level features:

Product level features are data which are mapped by considering the product as whole system. Some of the product level features mapped are:
Breather or pressure vent:
Starter-Motor Pressure Vent
Starter-Motor5
Breather made up of rubber is present to regulate the pressure built-up inside the motor by releasing excess pressure to the atmosphere.
Damper provided between solenoid and motor casing:
Starter-Motor Damper
Starter-Motor7
Rubber damper is used between solenoid and motor casing to reduce transfer of vibrations from motor to solenoid during the meshing of pinion gear with flywheel.
Ground Provision:
Starter-Motor Ground
Starter-Motor Lock Clamp
Metal bracket acts as a ground for this starter motor which is mounted to the backplate of the motor casing using a M6 hex head bolt and a washer.
Part level features:
These features are mapped by considering individual parts of the starter motor as a separate system which gives us a proper understanding of all the individual parts present in the starter motor. Some of the part level features are:
Stator type:
Starter-Motor Type
Starter-Motor Case

Four permanent magnets which acts as a stator are glued and separated using clips inside the permanent magnet casing which helps in rotating the rotor made up of electromagnets.

Gear Reduction type:
Starter-Motor Gear reduction type
Stator motor gear
Commercial vehicles require a higher torque due to the size of its flywheel when compared with passenger vehicles hence the planetary gear set is used for gear reduction. Here the input is given through sun gear and output is taken from the carrier or planetary gears.
Spline gear:
Starter-Motor Spline Gear
Starter-Motor rotate gear
Longitudinal and rotational motion is observed while the pinion gear moves along the shaft which is possible due to the spline gear provided on the planetary carrier output shaft, which also helps in better meshing of the pinion gear with Flywheel.
Specification mapped in starter motor
Specifications are categorised into two types:
  • Product level specification
  • Part level specification Some of the product level
Some of the product level specifications are mentioned below:
Starter-Motor Technical Specification-table
Some of the part level specifications are mentioned below:
Starter-Motor Technical Specification-table
Bill of materials generated from xcPEP
A product level BOM is first created on xcPEP which outlines the basic data of the product as an entity. The details mapped here are weight, box dimensions, supplier data, mounting method and mounting locations. Orthographic and isometric views of part and any information present on the part(information stickers)are captured and updated.
Starter-Motor Product Info & BOM parameter
Starter-Motor weight measurement
Once the part level data entry is done, the part is tore down into different sub-assemblies or sub-systems based on its functionality. The subsystem list is represented in hierarchical structure with part number at the top of the list.

After mapping all the product data, the product is further divided into sub systems for which the same data as the product are also mapped.

The sub system of the product are further torn down to last level and all the individual parts are created under their respective sub systems.

Starter-Motor BOM hierarchy

The created last level parts are then mapped with the details like box dimensions, Materials, Surface coating and thickness, Supplier data, Manufacturing process(Primary, Secondary and tertiary manufacturing process) and dependencies.

Starter-Motor BOM hierarchy
Architectural Study of Starter Motor

Product level architecture is categorised into:

  • Packaging diagram
  • Interface diagram
Packaging diagram:

All the major dimensions required to design a part is given under packaging diagram. The dimensions in all the orthographic views are marked.

Summary table is provided where the fastener details such as type, Msize and mounting locations are provided

Starter-Motor Packaging
Starter-Motor Packaging
Starter-Motor Packaging
Interface diagram:
Interface diagram consists of all the details regarding the interface between the parts. Electrical interface diagram consists of all the details regarding electrical connections such as connector details, male and female connectors, fastener details.
Starter-Motor Electrical interface
Exploded View
Exploded view is provided to understand the series in which the parts are mounted to each other. The exploded view of the starter motor is provided below.
Starter-Motor Exploded View
Exploded View of GDU

GDU is provided as a unit inside the starter motor where planetary gear set is used for torque multiplication. The GDU unit consists of three planetary gears, a ring gear and a sun gear.

Input is given to sun gear which helps in rotating planet gears which is guided with the help of the ring gear. Starter motor transmits the power to the pinion gear through the planetary carrier, which then the power is transmitted to the flywheel.

Starter-Motor GDU Exploded View
  • For one rotation of the planetary carrier the sun gear has to rotate six times.
Cut Section View
Cut Section view is used to understand the interior connection of the individual parts present inside the motor.
Starter-Motor MID Motor Section View
Starter-Motor Top Cut Section View