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New demands on scroll compressor bearings, solved with NORGLIDE® HPT

September 26th, 2022

Superior wear resistance and reduced friction for increased efficiency in scroll compressor applications

Compressor manufacturers are looking to reduce compressor size while increasing efficiency. The bearings used to guide the rotating scroll need to provide superior tribological performance and excellent wear resistance to ensure reliable and predictable performance over lifetime.

Industry requirements for thermal management systems used in electric vehicles and for residential housings are evolving. The demands of these growing markets are presenting new technical challenges for improved friction control:

  • over lifetime
  • under high loads, and
  • at high speeds 

Current and future trends in compressor motors are moving towards increasing efficiency and performance while reducing size. In efforts to reduce size, compressor motors must run at higher revolutions per minute (rpms) to compensate for loss volume. Therefore, the increased speeds and more compact designs will force bearings to operate at higher pressure-velocities and elevated temperatures.

 

Increased efficiency and more compact designs for scroll compressors

Scroll type compressors are gaining popularity in the heating, ventilation and air conditioning (HVAC) automotive market due to their high volumetric efficiency, quiet operation and compact size when compared to other pump types. Typical applications using scroll compressors include cabin temperature control for road vehicles including fully electric vehicles (EVs). Currently, a roller type bearing (ball bearing) is used to support and guide the rotating scroll. As the trends are moving towards more compact designs, a plain bearing, designed specifically as a scroll compressor bearing, is preferred for scroll applications. Moreover, scroll compressor bearings, also called plain bearings contain no moving parts hence reducing vibrations while providing a higher level of reliability (see figure 1).

 

NORGLIDE® HPT plain bearing guiding the rotating scroll of a scroll compressor

Figure 1. NORGLIDE® HPT plain bearing guiding the rotating scroll of a scroll compressor

 

Scroll compressor application bearing requirements

There are 4 main desirable requirements that engineers look for in bearings used in scroll compressor systems, these are:

  • High pressure-velocity-temperature (p-v-T)
  • Low friction
  • Increased efficiency
  • Premium wear resistance in boundary lubrication

 

NORGLIDE® HPT for scroll bearings

Our NORGLIDE® HPT material was specifically developed for the production of scroll bearings. Perfect for high pressure-velocity-temperature (p-v-T) applications using oil lubrication, such as scroll compressors. It consists of a specially formulated PEEK tape  that is laminated to a steel backing (see figure 2). The HPT material’s smooth surface structure promotes hydrodynamic lubrication at relatively low speeds and superior wear resistance in boundary lubrication. In addition, the high service temperature capability of NORGLIDE® HPT material insures:

  • Reliability 
  • Long life  
  • Predictable performance

for scroll compressor applications. The formulated PEEK tape is also inert and chemically resistant to refrigerants or working fluids used in typical scroll compressors.

NORGLIDE HPT scroll compressor composition

 

NORGLIDE HPT scroll bearing

Figure 2: NORGLIDE® HPT – formed bushing and its composition

 

Tribology performance of NORGLIDE® HPT

Using tribology,  we are able to test the wear behavior of NORGLIDE® HPT in motion. We use in-house equipment like tribometers for fundamental and Journal Bearing Testers (JBT) for application testing to determine coefficient of friction (COF) and wear performance of our NORGLIDE® HPT bearings. Stribeck curves (= COF as a function of shaft surface velocities) are widely used to determine the lubrication regime of the bearing and shaft interface.

During startup, a hydrodynamic bearing must first operate in a boundary lubrication region prior to operating in hydrodynamic region. Ideally, an engineer will always attempt to design a bearing to operate in hydrodynamic to reduce wear and minimise friction. However, the conditions to generate a hydrodynamic region may not always be possible; lack of oil or low rpm may drive the bearing system to operate in boundary lubrication. A low friction material having excellent wear rate characteristics is desirable. Our HPT material has been designed and tested for this purpose.

Stribeck curves lubrication regime testing

 

Speak to the experts at Saint-Gobain

At Saint-Gobain, we are constantly striving to develop new materials and push boundaries. Our engineer-to-engineer  approach to designing components challenges conventions to create innovative solutions that you can’t achieve with off-the-shelf products.

Speak to our team to discuss your engineering challenges and learn more about our state-of-art materials. Contact us through our online form or email us at makingabigdifference@saint-gobain.com.