You are here

  1. Home
  2. Your Industry
  3. Automotive
  4. Chassis
  5. Stator Mount Solution for Automotive E-motors

CONTACT US

 

Stator Mount Solution for Automotive E-motors

RENCOL® Tolerance Rings to simply fix the electric motor stator to the housing. 
 
A significant trend in the automotive industry is the shift to lightweight design. This shift has led to the use of different materials such as aluminium. In the electric motor market this can cause problems due to difference in the thermal expansion coefficients. The aluminium housing will expand at a higher rate than the iron-based stator which can cause a drop off in retention force and, therefore, result in a dislodged stator. 
 
Other issues are associated with the assembly process where stator mounting solutions such as the use of adhesive or shrink-fitting require energy-intensive heating steps. 
 

Mount stator motor housing assembly concentricity tolerance ring rencol

 
RENCOL® technology offers solutions to these issues, aided by system level simulation, optimising the stator joint design. The competency offered by Saint-Gobain has led to simplified assembly processes and better electric motor stator retention forces throughout the operating temperature range and an increase of the temperature range.
 
These benefits are achieved without sacrificing concentricity of the stator and rotor, enabling an efficient system in terms of input power and functional output power.

 

Our White Paper details the application benefits of using a tolerance ring as a stator mount solution. Our technology provides a solution that allows for the removal of adhesives and shrink-fitting that requires energy-intensive heating steps. Download the White Paper by clicking on the link. 
 
 

 

RENCOL® Tolerance Ring

  • Increased tolerances of mating components
  • Use of dissimilar materials
  • Control of NVH properties of EPS motor
  • Reduce number of fixing components / motor components
  • Simple to assemble

 

RENCOL® Thermoclad

Thermoclad has been designed to combine the benefits of tolerance rings whilst solving the problem of thermal transfer, a particularly important factor for electric motors.

The technology addresses thermal transfer capability of tolerance rings so they could be used more effectively with stator mounting applications. Find out more about our Thermoclad bi-metallic technology.

 

Using a tolerance ring brings many benefits as stator mount solution. Each benefit, detailed below, solves the challenges being faced today by automotive manufacturers and engineers, here we detail how. 

Smart Design Assembly Benefits of RENCOL Tolerance Ring in Automotive Stator MountAssembly Benefits of RENCOL® Tolerance Ring

Retention Over Temperature

The dimensions between the stator and housing are able to vary, usually due to thermal expansion but also manufacturing tolerance stack-ups, whilst the waves apply a consistent retention force.

 

Retention force over temperature stator motor mount Tolerance Ring Rencol
A numerically obtained example of push out force as a function of temperature including manufacturing tolerance effects. The RENCOL® Tolerance Ring used in this example retains more retention force than the press fit solution, when subject to increasing temperatures.

 

Perfect Fit Assembly Benefits of RENCOL Tolerance Ring in Automotive Stator MountAssembly Benefits of RENCOL® Tolerance Ring

Assembly Force

The RENCOL® product is assembled by applying an axial force with a press to insert the stator into the aluminium housing. Once assembled, no curing or settling time is required.

 

Assembly Force to assemble RENCOL Tolerance Ring | Saint-Gobain
Assembly force as a function of displacement. The peak force required to assemble the RENCOL® Tolerance Ring solution is much lower than the room temperature press fit solution.

 

Perfect Fit Cost Saving Example | Saint-Gobain Smart Design Cost Saving Example | Saint-GobainCost Saving Example

An example of the cost savings that can be achieved with RENCOL® Tolerance Rings as an electric motor stator mounting solution is outlined as follows.

Conditions:

  • Based on an EPS motor semi-automatic assembly line, producing 1 million units per year throughout a 10-year project life
  • Focus on the operation to fix the stator only, not the full cost of assembly of an EPS motor

Available methods and assembly steps to consider:

  • Adhesive fixing - application, heat cure and cool cycle
  • Interference fit with ‘heat shrink’ -  additional machining on housing bore, heating and cooling cycles
  • Tolerance Ring – apply to housing, then press in the stator
  Heat Shrink Adhesive Tolerance Ring
Cost per year €3,035K €3,115K €2,400K
Savings by using a tolerance ring €635K €715K -

 

Even in just one year, significant savings can be gained by using a tolerance ring fixing instead of adhesive or heat shrink methods. 

Noise Free Stator Mount Bearings | Saint-GobainNoise Free

Saint-Gobain’s engineers use finite element analysis techniques to perform modal analysis of stator mount assemblies. 

Modal Analysis of Stator Mount Assemblies | Saint-Gobain

They can tune the dynamic stiffness of the RENCOL® products so they can isolate vibration or shift natural frequencies out of the operating ranges.

Experimental verification of the modal vibrations can be obtained through impact testing and the noise levels of the system can be analysed in our anechoic chamber by our noise and vibration experts.