Mitsubishi Heavy Industries Technical Review Vol. 56 No. 4 (December 2019)
1Large Capacity Electric Compressor for Air Conditioning
System of Hybrid Electric Vehicles

M i ts u b i s h i H e a v y I n d u s t r i e s T h e r m a l
S ystems, Ltd.

Mitsubishi Heavy Industries Thermal Systems, Ltd. has marketed electric compressors for air
conditioning systems of hybrid electric vehicles since 2007, and achieved the industry's top class ofsmall, light, and more efficient compressors featuring its unique scroll technology, inverter control
system and optimized internal structure*1. We have developed a new series of large-capacity
electric compressors to meet the needs of electric vehicles such as the promotion of battery cooling
during rapid charging and the expansion of heating capacity for application to heat pumps. The
developed product has achieved a significant increase in cooling capacity while minimizing theincrease in body size by optimizing the internal specifications in comparison with the current
product.

|1. Product characteristics
As shown in Figure 1, the layout of the inverter, motor and scroll of the developed productfollows the design of the current product. The compression mechanism uses an improved 3D scroll
profile*2 which was redesigned for the developed product. By enlarging the motor size andredesigning the inverter, the electric load capacity was also expanded, and the effect of increasing
the cooling capacity can be sufficiently leveraged.
In addition, by designing the drive system components such as bearings in the same size as
the current product in order to maintain the same body diameter as the current product andminimize the increase in overall length, we aimed to achieve packaging that does not restrict
vehicle mounting.

Figure 1 Appearance comparison between current and developed
products

Mitsubishi Heavy Industries Technical Review 56 No. 4 (December 2019)2|2. Increasing capacity
To respond to the needs of the market in detail, we have developed two types of productswith different displacement volumes*3.
Figure 2 gives a comparison of the cooling capacity between the current and the developed
product. The horizontal axis shows the ratio of overall compressor length and the vertical axis
shows the ratio of cooling capacity using the current product as a base of 100%.

Figure 2 Comparison of cooling capacity between the current
product and the developed products

In the case of developed product A, the compressor overall length ratio increases by 9% andthe cooling capacity ratio decreases by 21%. In the case of developed product B, the compressor
overall length ratio increases by 13% and the cooling capacity ratio decreases by 53%.
Both models have achieved a significant increase in cooling capacity as the total length of thecompressor increases.
Figure 3 gives a comparison of the noise level between the current product and developed
product B. The horizontal axis shows the ratio of cooling capacity by percentage with using thecurrent product’s maximum speed as a base of 100% and the vertical axis shows the noise level bydecibel.
Developed product B achieved the same noise level as the current product with the same
cooling capacity.

Figure 3

Comparison of noise between the current and developed products|3. Future Development
Figure 4 shows the development history and future development of our electric compressors.
The developed product introduced here is being further developed with the aim of launching it on
the market in 2023. In addition to increasing the cooling capacity, simplified structural and noise
reduction technologies are also being developed.
Our company will continue to contribute to the spread of electric vehicles and theimprovement of the global environment by developing products that meet market needs.

Mitsubishi Heavy Industries Technical Review 56 No. 4 (December 2019)
3Figure 4*1

Development flow of our company’s electric compressor

See Mitsubishi Heavy Industries Technical Review 54-2 (2017) “Development of Electric
Compressors for Air Conditioning Systems of Hybrid Electric Vehicles.”*2 Highly-efficient 3D scroll with reduced leakage during compression process.
“3D Scroll” is a registered trademark of Mitsubishi Heavy Industries Thermal Systems, Ltd. in Japan.
*3 The suction volume of a scroll per one shaft rotation.