1166, Page 1
WEAR-LESS TECHNOLOGY FOR ROTARY COMPRESSOR
USING CO2 REFRIGERANT
Naotaka Hattori1*, Hideto Nakao2, Tomoo Takayama3, Ikenaga Kaoru4
1
Mitsubishi Electric Engineering Corporation Shizuoka Engineering Office
3-18-1, Oshika, Suruga-ku, Shizuoka-City, Japan
Tel: +81-54-287-3112, Fax: +81-54-287-3127, Postcode: 422-8528
E-mail: [email protected]
2
Mitsubishi Electric Corporation Advanced Technology R&D Center
8-1-1, Tsukaguchi-Honmachi, Amagasaki-City, Hyogo, Japan
Tel: +81-6-6497-7582, Fax: +81-6-6497-7291, Postcode: 661-8661
E-mail: [email protected]
3
Mitsubishi Electric Corporation Manufacturing Engineering Center
8-1-1, Tsukaguchi-Honmachi, Amagasaki-City, Hyogo, Japan
Tel: +81-6-6497-7528, Fax: +81-6-6497-7601, Postcode: 661-8661
E-mail: [email protected]
4
NDK, Incorporated
3-10-14,Miyasimo Sagamihara-City,Kanagawa,japan
Tel: +81-42-774-1233, Fax: +81-42-773-1674, Postcode:229-1112
E-mail: [email protected]
ABSTRACT
We have developed a new CO2 heat pump water heater compressor with a single rotary mechanism in practical
use for the first time in the world. CO2 refrigerant doesn't destroy the ozone layer, and the global warming potential
(GWP) is less than 1/1000 in comparison to hydro-fluorocarbon refrigerants. However the operating pressure of CO2
refrigerant is approximately three times as high as that of R410A refrigerant. Therefore, it is important to secure the
reliability of sliding portions under high operating pressure conditions.
The single rotary mechanism is used in mainstream R410A refrigerant air conditioning systems. However, CO2
refrigerant has not been used practically for CO2 refrigerant systems due to the difficult issue of securing the
durability against vane wear. We worked on this issue of reliability for the sliding portion between the vane tip and
the periphery of the rolling piston, by applying a coating DLC-Si to the vane. As a result, even after a long duration,
the DLC-Si coated vane is hardly worn-out, only the surface roughness is smoothed. We were able to achieve an
excellent level of wear durability, which we call “WEAR-LESS”.
1. INTRODUCTION
In Japan, the heat pump type water heater (Figure 1) that uses a
natural refrigerant CO2 has been rapidly spreading, after it was
commercialized in 2001. The single rotary mechanism has been the
mainstream of R410A refrigerant air conditioning systems, because
of it is simple mechanism and high efficiency. However, the
operating pressure of the CO2 refrigerant is approximately three
times as high as that of R410A refrigerant. It is difficult to secure
the reliability of the sliding portion between the vane tip and the
periphery of the rolling piston under high operating pressure
conditions. Therefore, it had not been able to be used practically.
We worked on securing the reliability against the vane wear. As a
result, we started mass production of the single rotary compressor
using CO2 refrigerant in October, 2005
㪮㪸㫋㪼㫉㩷㪫㪸㫅㫂㩷㪬㫅㫀㫋
㪟㪼㪸㫋㩷㪧㫌㫄㫇㩷㪬㫅㫀㫋
㪚㫆㫄㫇㫉㪼㫊㫊㫆㫉
㩿㪙㫌㫀㫃㫋㪄㫀㫅㪀
㪝㫀㪾㪅 㪈 㪘㫇㫇㪼㪸㫉㪸㫅㪺㪼㩷㫍㫀㪼㫎㩷㫆㪽㩷㪮㪸㫋㪼㫉㩷㪟㪼㪸㫋㪼㫉㩷㪬㫅㫀㫋
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 2
2. ROTARY COMPRESSOR
2-1. Single Rotary Compressor using CO2 refrigerant
Table1 shows the specification of the single rotary compressor using CO2 refrigerant. It is used for our heat pump
water-heater units of 4.5kW, 6.0kW and 7.2kW. Figure 2 shows a cross-sectional view of the Mitsubishi CO2
compressor. The structure of the compressor is designed to withstand high pressure CO2 refrigerant. The compressor
uses a “Joint-lapped” brush-less DC motor that is used in our compressor installed in conventional refrigerant air
conditioners.
㪪㫌㪺㫋㫀㫆㫅㩷㪤㫌㪽㪽㫃㪼㫉
㪫㪸㪹㫃㪼㩷㪈㩷㪪㫇㪼㪺㫀㪽㫀㪺㪸㫋㫀㫆㫅㩷㫆㪽㩷㫋㪿㪼㩷㪚㪦㪉㪄㪪㫀㫅㪾㫃㪼㩷㪩㫆㫋㪸㫉㫐㩷㪚㫆㫄㫇㫉㪼㫊㫊㫆㫉
㪤㫆㪻㪼㫃㩷㪥㪸㫄㪼
㪢㪯㪙㪇㪋㪌㪝
㪚㫆㫄㫇㫉㪼㫊㫊㫆㫉㩷㪫㫐㫇㪼
㪪㫀㫅㪾㫃㪼㩷㪩㫆㫋㪸㫉㫐
㪛㫀㫊㫇㫃㪸㪺㪼㫄㪼㫅㫋
㪋㪅㪌㪺㪺
㪬㫊㪸㪾㪼
㪟㪧㩷㪮㪸㫋㪼㫉㩷㪟㪼㪸㫋㪼㫉㪋㪅㪌㪆㪍㪅㪇㫂㪮㪆㪎㪅㪉㫂㪮
㪪㫀㫑㪼
㱢㪈㪉㪉㬍㪉㪎㪏㫄㫄
㪤㫆㫋㫆㫉
㪙㪣㪛㪚㪤㩿㪡㫆㫀㫅㫋㪄㪣㪸㫇㫇㪼㪻㩷㪤㫆㫋㫆㫉㪀
㪮㪼㫀㪾㪿㫋
㪈㪉㪅㪎㪢㪾
㪛㫀㫊㪺㪿㪸㫉㪾㪼㩷㪧㫀㫇㪼
㪫㪿㫀㪺㫂㩷㪪㪿㪼㫃㫃
㪤㫆㫋㫆㫉㩿㪙㪣㪛㪚㪤㪀
㪚㫉㪸㫅㫂㫊㪿㪸㪽㫋
㪝㫉㪸㫄㪼
㪚㫐㫃㫀㫅㪻㪼㫉
㪚㫐㫃㫀㫅㪻㪼㫉㩷㪟㪼㪸㪻
㪝㫀㪾㪅 㪉 㪪㫀㫅㪾㫃㪼䇭㪩㫆㫋㪸㫉㫐䇭㪚㫆㫄㫇㫉㪼㫊㫊㫆㫉䇭㪽㫆㫉䇭㪚㪦㪉
2-2. Rotary Mechanism
Figure 3 shows the compression movement of the rotary
mechanism. The rotary compressor mechanism consists of a
rolling piston that rotates eccentrically in its cylinder and a
vane installed in a vane slot in the cylinder, which reciprocates
along the slot causing the vane to move along the periphery of
the rolling piston. As a result of the vane’s movement, suction
and compression chambers are formed inside the cylinder and
the volume of each chamber changes in accordance with the
rotation of the crankshaft to provide compression. When the
compression chamber gas equals the discharge pressure, a
discharge valve is opened, and compressed gas is discharged.
㪭㪸㫅㪼
㪛㫀㫊㪺㪿㪸㫉㪾㪼㩷㪭㪸㫃㫍㪼
㪩㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫆㫅
㪚㫐㫃㫀㫅㪻㪼㫉
㪚㫉㪸㫅㫂㫊㪿㪸㪽㫋
㪛㫀㫊㪺㪿㪸㫉㪾㪼
㪪㫌㪺㫋㫀㫆㫅
㪇㫦
㪉㪎㪇㫦
㪐㪇㫦
㪈㪏㪇㫦
㪝㫀㪾㪅 㪊 㪤㪼㪺㪿㪸㫅㫀㫊㫄㩷㫆㪽㩷㫉㫆㫋㪸㫉㫐㩷㫋㫐㫇㪼
2-3. Issues in applying the single rotary mechanism for CO2 refrigerant
The rotary mechanism has a simple structure, and it has
light weight in comparison with other compression methods.
Component-parts of rotary compressor have an advantage, as
they are easy to machine because their shapes are based on
cylinders and plane surfaces. Therefore it is the mainstream
type of compressor for conventional R410A refrigerant air
conditioners. However, since the vane tip and the periphery of
the rolling piston slide while receiving the load pressure, it is
difficult to maintain the lubricating oil in this sliding portion,
so the sliding condition is harsh. Figure 4 shows the sliding
portion of the vane and the rolling piston. As shown in Figure
5, the operating pressure of the CO2 refrigerant is
approximately three times as high as R410A refrigerant.
Therefore, it is too harsh to secure the reliability of the vane
with a rotary mechanism.
㪧㫉㪼㫊㫊㫌㫉㪼㩷㫃㫆㪸㪻㫀㫅㪾
㪪㫃㫀㪻㫀㫅㪾䇭㪺㫆㫅㪻㫀㫋㫀㫆㫅
㩷㩷㩷㩷㩷㩷㩷㩷㩷㩷㩷㩷㩷㫀㫊䇭㪿㪸㫉㫊㪿
㪛㫀㫊㪺㪿㪸㫉㪾㪼
㩷䇭㫇㫉㪼㫊㫊㫌㫉㪼
㪭㪸㫅㪼
㪩㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫀㫆㫅
㪪㫌㪺㫋㫀㫆㫅
䇭㫇㫉㪼㫊㫊㫌㫉㪼
㪝㫀㪾㪅 㪋 㪪㫃㫀㪻㫀㫅㪾䇭㫇㫆㫉㫋㫀㫆㫅䇭㫆㪽䇭㫋㪿㪼䇭㫍㪸㫅㪼
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 3
Figure 6 shows the life test results of rotary compressors with CO2 refrigerant in the early stages of development.
A nitrided vane was used which implemented the conventional rotary compressor for R410A refrigerant air
conditioners. The axis of abscissa shows the life test period ratio, and the axis of the ordinate shows wear ratio of
the vane. The required life time is 1.0, and the wear tolerance-limit of the vane is 1.0. The result of the experiments,
wear amount of the nitrided vane exceeded the wear tolerance-limit by 1/5 of the required life time. Therefore, this
result shows how difficult it was to establish a specification for practical use of CO2 refrigerant by the single rotary
mechanism. We think that was necessary to develop a new technology.
㪈㪈㪅㪊
㪈㪇
㪏
㪦㫇㪼㫉㪸㫋㫀㫅㪾㩷㫇㫉㪼㫊㫊㫌㫉㪼
㩷㪘㫇㫇㫉㫆㫏㪅㩷㪊㬍
㪍
㪋
㪟㫀㪾㪿㩷㫇㫉㪼㫊㫊㫌㫉㪼㩷㫊㫀㪻㪼
㪊㪅㪋
㪋㪅㪉
㪉
㪇
㪣㫆㫎㩷㫇㫉㪼㫊㫊㫌㫉㪼㩷㫊㫀㪻㪼
㪮㪼㪸㫉㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫍㪸㫅㪼
㪦㫇㪼㫉㪸㫋㫀㫅㪾㩷㫇㫉㪼㫊㫊㫌㫉㪼䈀㪤㪧㪸䈁
㪈㪉
㪈㪅㪇
㪉㪅㪇
㪈㪅㪏
㪈㪅㪍
㪈㪅㪋
㪈㪅㪉
㪈㪅㪇
㪇㪅㪏
㪇㪅㪍
㪇㪅㪋
㪇㪅㪉
㪇㪅㪇
㪩 㪋㪈㪇㪘
㪚㪦㪉
㪽㫆㫉㩷㫉㪼㫊㫀㪻㫌㪸㫃㩷㫌㫊㪼 㪽㫆㫉㩷㫎㪸㫋㪼㫉㪄㪿㪼㪸㫋㪼㫉
㪸㫀㫉㪄㪺㫆㫅㪻㫀㫋㫀㫆㫅㪼㫉
㫌㫅㫀㫋
㫅㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪩㪼㫈㫌㫀㫉㪼㪻㩷㫃㫀㪽㪼㩷㫋㫀㫄㪼
㪮㪼㪸㫉㩷㫋㫆㫃㪼㫉㪸㫅㪺㪼㪄㫃㫀㫄㫀㫋
䇭䇭䇭㩷㩷㫆㪽㩷㫅㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪇㪅㪉
㪇㪅㪉
㪇㪅㪇
㪇㪅㪋
㪇㪅㪍
㪇㪅㪏
㪈㪅㪇
㪈㪅㪉
㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫇㪼㫉㫀㫆㪻㩷㫉㪸㫋㫀㫆
㪝㫀㪾㪅 㪌 㪚㫆㫄㫇㪸㫉㫀㫊㫆㫅㩷㫆㪽㩷㫆㫇㪼㫉㪸㫋㫀㫅㪾㩷㫇㫉㪼㫊㫊㫌㫉㪼
㪝㫀㪾㪅 㪍 㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫉㪼㫊㫌㫃㫋㩷㫆㪽㩷㫅㫀㫋㫉㫀㪻㪼㪻㩷㪭㪸㫅㪼
3. IMPROVEMENT OF SLIDING DURABILITY AT THE VANE TIP
In the history of refrigeration units, there were some turning points when rotary compressors needed to improve
the specification of sliding durability at the vane tip, such as increasing sliding speed by applying inverter control
and increasing operating pressure by changing refrigerant from R22 to R410A. As an improvement action, we
changed the material of the vane, and added a surface treatment to the vane. However, these methods merely
decreased the amount of wear on the vane. We achieved “WEAR-LESS”, the reliability of the sliding portion by
coating DLC-Si to the vane.
Figure 7 shows the life test results of DLC-Si coated
vane. Results of the life tests, DLC-Si coated vane is
hardly worn-out, and the surface roughness only becomes
smooth. Therefore the DLC-Si coated vane is effectively
“WEAR-LESS”. The rolling piston does not wear out
equally either. Figure 8 shows the surface profile of a
DLC-Si coated vane before and after the life test, and was
compared with nitrided vane. The surface profile of
nitrided vane was coarse. However, the surface profile of
DLC-Si coated vane was still smooth and not worn. It is
understood that the DLC-Si coated vane has excellent
sliding characteristics.
㪮㪼㪸㫉㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫍㪸㫅㪼
3-1 “WEAR-LESS” coating DLC-Si to the vane
㪉㪅㪇
㪈㪅㪏
㪈㪅㪍
㪈㪅㪋
㪈㪅㪉
㪈㪅㪇
㪇㪅㪏
㪇㪅㪍
㪇㪅㪋
㪇㪅㪉
㪇㪅㪇
㫅㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪩㪼㫈㫌㫀㫉㪼㪻㩷㫃㫀㪽㪼㩷㫋㫀㫄㪼
㪮㪼㪸㫉㩷㫋㫆㫃㪼㫉㪸㫅㪺㪼㪄㫃㫀㫄㫀㫋
䇭䇭䇭㩷㩷㫆㪽㩷㫅㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪩 㪼㫊 㫌㫃 㫋㩷 㫆㪽 㩷 㪛 㪣㪚㪄㪪㫀 㩷 㪺㫆㪸 㫋㪼㪻
㩷 㫍 㪸 㫅㪼䇭㵺㪠㫋㩾㫊 䇭㫎㪼㪸 㫉㩷 㫃 㪼㫊 㫊
㪇㪅㪇
㪇㪅㪉
㪇㪅㪉
㪻㫀㫉㪼㪺㫋㫀㫆㫅㩷㫆㪽
㩷㫄㪼㫊㫌㫉㪼㫄㪼㫅㫋
㪘㪽㫋㪼㫉㩷㩿㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫉㪸㫋㫀㫆㩷㫀㫊㩷㪇㪅㪊䋩
㪩㫑㩷㪔㩷㪇㪅㪎㪋䇭㫄㫀㪺㫉㫆㫅
㪪㫌㫉㪽㪸㪺㪼㩷㫇㫉㫆㪽㫀㫃㪼㩷㫀㫊㩷㪺㫆㪸㫉㫊㪼
㪩㫑 㪔 㪈㪅㪈㪍 㫄㫀㪺㫉㫆㫅
㪈㪅㪇㩷㫄㫀㪺㫉㫆㫅
㪇㪅㪌㫄㫄
㪈㪅㪇㩷㫄㫀㪺㫉㫆㫅
㪇㪅㪌㫄㫄
㪇㪅㪍
㪇㪅㪏
㪈㪅㪇
㪈㪅㪉
㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫇㪼㫉㫀㫆㪻㩷㫉㪸㫋㫀㫆
㪝㫀㪾㪅 㪎 㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫉㪼㫊㫌㫃㫋㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀㩷㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪥㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪙㪼㪽㫆㫉㪼
㪇㪅㪋
㪛 㪣㪚㪄㪪䌩㩷㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪙 㪼㪽㫆㫉㪼
㪘㪽㫋㪼㫉㩷㩿㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫉㪸㫋㫀㫆㩷㫀㫊㩷㪈㪅㪉㪀
㪪㫌㫉㪽㪸㪺㪼㩷㫇㫉㫆㪽㫀㫃㪼㩷㫀㫊㩷㫊㫄㫆㫆㫋㪿
㪩㫑㩷㪔㩷㪇㪅㪌㪊䇭㫄㫀㪺㫉㫆㫅
㪈㪅㪇㩷㫄㫀㪺㫉㫆㫅
㪇㪅㪌㫄㫄
㪩㫑 㪔 㪇㪅㪉㪏 㫄㫀㪺㫉㫆㫅
㪈㪅㪇㩷㫄㫀㪺㫉㫆㫅
㪇㪅㪌㫄㫄
㪝㫀㪾㪅 㪏 㪪㫌㫉㪽㪸㪺㪼㩷㫊㪿㪸㫇㪼㩷㫆㪽㩷㫍㪸㫅㪼㩷㪹㪼㪽㫆㫉㪼㩷㪸㫅㪻㩷㪸㪽㫋㪼㫉㩷㫋㪿㪼㩷㫃㫀㪽㪼㩷㫋㪼㫊㫋
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 4
3-2 DLC-Si coated vane
㪛㪣㪚㪄㪪㫀㩷㪺㫆㪸㫋㫀㫅㪾㩷㪽㫀㫃㫄
㪥㫀㫋㫉㫀㪻㪼㩷㫃㪸㫐㪼㫉
㪙㪸㫊㪼㩷㫄㪸㫋㪼㫉㫀㪸㫃
㪝㫀㪾㪅 㪐 㪪㫋㫉㫌㪺㫋㫌㫉㪼㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀㩷㪺㫆㪸㫋㫀㫅㪾㩷㪭㪸㫅㪼
㪮㪼㪸㫉㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㩷㫉㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫆㫅
DLC-Si is the term for “Diamond-Like Carbon-Silicon”,
which is a film of DLC containing silicon. Figure 9 shows
the structure of the DLC-Si coated vane. The nitrided layer
is formed on the base material, and the DLC-Si film is
coated on top of it. The characteristic of the DLC film is
hard with a crystal structure similar to a diamond, so the
DLC itself is not worn out. Moreover, the other part is not
worn out by the characteristic of DLC such as flexible
graphite and solid lubricity. The DLC-Si film has the high
adhesion strength by containing the silicon compared with
conventional DLC that does not contain silicon. Coating
technologies such as DLC have existed for some time to
reduce friction and wear. We evaluated several coating
technologies. However, there were many issues that were
wearing out the rolling piston and peeling off the coating
film. Figure10 shows the result of rolling piston wear ratios
when the CrN coated vane was tested compared to the DLCSi coated vane. The DLC-Si coated vane does not wear out
the rolling piston compared with the CrN coated vane.
Conventional DLC film that does not contain silicon was
developed in the 1970's. And it has been used for tools,
metal molds and other applications. However, practical use
of conventional DLC came later, because of two issues, the
first issue is the low adhesion strength, and the second issue
is that it was impossible to coat a high thickness film. We
tried to evaluate the life test of a conventional DLC coated
vane. As a result, it peeled off in the early test period
because of low adhesion strength. Figure11 shows a picture
of a peeled off the film. The adhesion strength of the DLCSi film is approximately twice as high as that of
conventional DLC film. Moreover, the film thickness of
conventional DLC film was only 0.5-1.0 micron, however it
is possible to produce more than 5micron thickness film in
the case of the DLC-Si film.
DLC-Si film improved the demerit of conventional DLC
film by containing the silicon, and it sliding characteristics
were improved.
㪉㪅㪇
㪩㪼㫈㫌㫀㫉㪼㪻㩷㫃㫀㪽㪼㩷㫋㫀㫄㪼
㪈㪅㪍
㪚㫉㪥㩷㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪈㪅㪉
㪇㪅㪏
㪛㪣㪚㪄㪪㫀 䇭㪺㫆㪸 㫋㪼㪻㩷 㫍 㪸 㫅㪼㩷 㪿㪸 㫉㪻㫃 㫐
㩷 㫎 㪼㪸 㫉㫊 㩷 㫆㫌㫋㩷 㫉㫆㫃 㫃 㫀 㫅㪾 㩷 㫇㫀 㫊 㫋㫆㫅㪅
㪇㪅㪋
㪇㪅㪇
㪇
㪇㪅㪉
㪇㪅㪋
㪇㪅㪍
㪇㪅㪏
㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫇㪼㫉㫀㫆㪻㩷㫉㪸㫋㫀㫆
㪈
㪈㪅㪉
㪝㫀㪾㪅 㪈㪇 㪣㫀㪽㪼㩷㫋㪼㫊㫋㩷㫉㪼㫊㫌㫃㫋㩷㫆㪽㩷㫉㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫆㫅㩷㫎㪼㪸㫉㩷㫉㪸㫋㫀㫆
㩷㪚㫆㫅㫍㪼㫅㫋㫀㫆㫅㪸㫃㩷㪛㪣㪚㩷㪽㫀㫃㫄㩷㫎㫀㫋㪿㫆㫌㫋㩷㫊㫀㫃㫀㪺㫆㫅㩷㫇㪼㪼㫃㪼㪻㩷㫆㪽㪽㪅
㩷㪙㪼㪺㪸㫌㫊㪼㩷㫀㫋㩷㪿㪸㫊㩷㫃㫆㫎㩷㪸㪻㪿㪼㫊㫀㫆㫅㩷㫊㫋㫉㪼㫅㪾㫋㪿㪅
㪝㫀㪾㪅 㪈㪈 㪩㪼㫊㫌㫃㫋㩷㫆㪽㩷㫃㫀㪽㪼㩷㫋㪼㫊㫋㩷㪽㫆㫉㩷㪺㫆㫅㫍㪼㫅㫋㫀㫆㫅㪸㫃㩷㪛㪣㪚㩷
3-3 Optimization of adhesion strength by controlling the silicon content When coating DLC-Si to the vane of the rotary compressor, it is necessary to secure enough adhesion strength
against peeling off the film. In this paragraph, I will describe the optimization of adhesion strength of the DLC-Si
film by the silicon content.
The peeling patterns of the DLC-Si coated vane of the rotary compressor are roughly divided into two groups as
follows:
Pattern A) Peeling at the surface film
Pattern B) Peeling at the interface between the DLC-Si film and the base material
The peeling pattern of “A” has a lot of small damage called “micro-picking”. The peeling pattern of “B”, the base
material surface is exposed in a wide area. In both peeling patterns, adhesion strength relates to the silicon
concentration in the DLC-Si film. The adhesion strength characteristics of the DLC-Si films are changed by silicon
concentration. We optimized the silicon concentration in the DLC-Si film and secured the adhesion strength of the
film. Figure 12 shows the relationship between silicon concentration and the adhesion strength ratio. Figure 13
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 5
shows the relationship between silicon concentration and the residual stress ratio. Figure 14 shows the relationship
between silicon concentration and the ratio of Young’s modulus.
㪩㪸㫋㫀㫆㩷㫆㪽㩷㪸㪻㪿㪼㫊㫊㫀㫆㫅㩷㫊㫋㫉㪼㫅㪾㫋㪿
㫆㪽㩷㫋㪿㪼㩷㪛㪣㪚㪄㪪㫀㩷㪽㫀㫃㫄
㪈㪅㪌
㪓㪧㪸㫋㫋㪼㫉㫅㩷㪙㪕
㪈㪅㪋
㪈㪅㪊
㪓㪧㪸㫋㫋㪼㫉㫅㩷㪘㪕
㪈㪅㪉
㪈㪅㪈
㪈
㪘㫇㫇㫉㫆㫏㪅㩷㪉㪇㩷㩼㩷㫀㫊㩷㫄㪸㫏㫀㫄㫌㫄㪅
㪇㪅㪐
㪇㪅㪏
㪇
㪈㪇
㪉㪇
㪊㪇
㪋㪇
㪪㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅㩷㫀㫅㩷㫋㪿㪼㩷㪛㪣㪚㪄㪪㫀㩷㪽㫀㫃㫄㩷䇼㫎㫋㩼䇽
㪝㫀㪾㪅 㪈㪉 㪫㪿㪼㩷㫉㪼㫃㪸㫋㫀㫆㫅㫊㪿㫀㫇㩷㪹㪼㫋㫎㪼㪼㫅㩷㫊㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅
㩷㪸㫅㪻㩷㫋㪿㪼㩷㪸㪻㪿㪼㫊㫀㫆㫅㩷㫊㫋㫉㪼㫅㪾㫋㪿㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀
As shown in Figure 12, The adhesion strength of the DLC-Si film depends on the silicon concentration. Adhesion
strength of DLC-Si film is maximized when the silicon concentration is approximately 20 %. If the silicon
concentration is lower or higher than 20 %, either way the adhesion strength declines. Adhesionstrength decreases
seriously when the silicon concentration becomes 10 % or less, resulting in peeling “pattern B”. In this case, it is
considered that the low adhesion strength is cased by the high residual stress due to the mismatch of the crystal
structure between the film and the base material. As you can see from Figure 13, when the silicon concentration is
low, the residual stress increases. Therefore, We assume that the residual stress of the film depends on the silicon
concentration. In the case of low silicon, high residual stress generates at the interface between the DLC-Si film and
the base material. The film peeling pattern by high silicon concentration is “pattern A”. From Figure 14, we can see
when the silicon concentration is high, the Young’s modulus decreases. We assume that a high silicon concentration
film is fragile and peels off at the surface of the film. Thus we controlled the silicon concentration of DLC-Si coated
film to approximately 20 %.
㪈㪅㪋
㪈㪅㪈
㪩㪸㫋㫀㫆㩷㫆㪽㩷㪰㫆㫅㪾㩾㫊㩷㫄㫆㪻㫌㫃㫌㫊
㪩㪸㫋㫀㫆㩷㫆㪽㩷㫉㪼㫊㫀㪻㫌㪸㫃㩷㫊㫋㫉㪼㫊㫊
㪈㪅㪉
㪈㪅㪇
㪇㪅㪏
㪇㪅㪍
㪇㪅㪋
㪇㪅㪉
㪇㪅㪇
㪈㪅㪇
㪇㪅㪐
㪇㪅㪏
㪇㪅㪎
㪇㪅㪍
㪇㪅㪌
㪇
㪌
㪈㪇
㪈㪌
㪉㪇
㪉㪌
㪊㪇
㪊㪌
㪪㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅㩷㫀㫅㩷㫋㪿㪼㩷㪛㪣㪚㪄㪪㫀㩷㪽㫀㫃㫄㩷䇼㫎㫋㩼䇽
㪝㫀㪾㪅 㪈㪊 㪫㪿㪼㩷㫉㪼㫃㪸㫋㫀㫆㫅㫊㪿㫀㫇㩷㪹㪼㫋㫎㪼㪼㫅㩷㫊㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅
㩷㪸㫅㪻㩷㫋㪿㪼㩷㫉㪼㫊㫀㪻㫌㪸㫃㩷㫊㫋㫉㪼㫊㫊㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀
㪇
㪌
㪈㪇
㪈㪌
㪉㪇
㪉㪌
㪊㪇
㪊㪌
㪪㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅㩷㫀㫅㩷㫋㪿㪼㩷㪛㪣㪚㪄㪪㫀㩷㪽㫀㫃㫄㩷䇼㫎㫋㩼䇽
㪝㫀㪾㪅 㪈㪋 㪫㪿㪼㩷㫉㪼㫃㪸㫋㫀㫆㫅㫊㪿㫀㫇㩷㪹㪼㫋㫎㪼㪼㫅㩷㫊㫀㫃㫀㪺㫆㫅㩷㪺㫆㫅㪺㪼㫅㫋㫉㪸㫋㫀㫆㫅
㩷㪸㫅㪻㩷㫋㪿㪼㩷㪰㫆㫌㫅㪾㵭㫊㩷㫄㫆㪻㫌㫃㫌㫊䇭㫉㪸㫋㫀㫆㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 6
3-4 Deposition of DLC-Si to the vane DLC-Si is deposited by the plasma CVD (Chemical Vapor
Deposition) method with gases of CH4 and a silicon gas such as
Si(CH3)4. Mass production of DLC-Si coated vane is processed by
NDK Incorporated Japan. Figure 15 shows the processing equipment
for mass production. By mass production processing, the vane can be
processed at the rate of several hundred pieces per one batch. We
developed the specification of the vane stage, the gas supply pipe,
flow rate of gases, and processing temperature to secure the
characteristics such as film thickness or adhesion strength for
exclusive use in this application.
㪝㫀㪾㪅 㪈㪌 㪫㪿㪼㩷㫇㫉㫆㪺㪼㫊㫊㫀㫅㪾㩷㪼㫈㫌㫀㫇㫄㪼㫅㫋㩷㫆㪽㩷㪛㪣㪚㪄㪪㫀
㩿㪘㩷㫇㫉㫆㪻㫌㪺㫋㩷㫄㪸㪻㪼㩷㫀㫅㩷㪥㪛㪢㪃㪠㫅㪺㫆㫉㫇㫆㫉㪸㫋㪼㪻㪀
4. THE WEAR-OUT DURABILITY OF THE DLC-Si COATED VANE
The vane tip of the rotary compressors comes in contact with the
periphery of the rolling piston, and slides. It involves both sliding
and rolling actions. If the load of this sliding portion is higher than
the wear limit of the material, the vane tip and the periphery of the
rolling piston wears out. However if the sliding portion is less than
the wear limit of the material, it does not wear out. Therefore, it is
possible to grasp the wear-out resistance of the vane by obtaining the
load that corresponds to the wear out limit rate and comparing the
maximum load rate for practical use. We obtained the load that
corresponds to the wear-out limit rate through experiments with an
abrasion tester (Figure 16). In Figure 16, the vane comes in contact
with the rolling piston through the load from the back, as the rolling
piston rotates by the motor drive. Therefore the contact formation of
the vane tip and the periphery of the rolling piston is a sliding action
only. Table 2 shows the conditions of the experiments, and figure 17
shows the result of experiments that compares the nitrided vane with
the DLC-Si coated vane. The experiment result shows a relationship
between the experimental time and the ratio of the vane wear. The
wear amount of DLC-Si coated vane is much lower than that of the
nitrided vane. Both wear amount of vanes have a tendency to be
saturated by progression of the test time. This is attributed to a
decrease in contact pressure due to the change from a line contact to
a surface contact, as the wear of vane increases.
㪫㪿㪼㩷㪺㫆㫅㫋㪸㪺㫋㩷㫇㫉㪼㫊㫊㫌㫉㪼
㫆㪽㩷㫃㫀㫅㪼㩷㪺㫆㫅㪸㪺㫋㩷㫀㫊㩷㪿㫀㪾㪿
㪭㪸㫅㪼
㪩㫆㫋㪸㫋㫀㫆㫅
㪩㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫆㫅
㪝㫀㪾㪅 㪈㪍 㪮㪼㪸㫉㩷㫋㪼㫊㫋㪼㫉㩷
㪫㪸㪹㫃㪼 㪉㩷㪚㫆㫅㪻㫀㫋㫀㫆㫅㩷㫆㪽㩷㫋㪿㪼㩷㫎㪼㪸㫉㩷㫋㪼㫊㫋
㪚㪦㪉㩷㫉㪼㪽㫉㫀㪾㪼㫉㪸㫅㫋
㪜㫅㫍㫀㫉㫆㫅㫄㪼㫅㫋
㪚㪸㫊㪼
㪭㪸㫅㪼㩷㫄㪸㫋㪼㫉㫀㪸㫃
㪩㫆㫃㫃㫀㫅㪾㩷㫇㫀㫊㫋㫆㫅
㫄㪸㫋㪼㫉㫀㪸㫃
㪣㫌㪹㫉㫀㪺㪸㫅㫋
㪣㫆㪸㪻
㪪㫃㫀㪻㫀㫅㪾㩷㫍㪼㫃㫆㪺㫀㫋㫐
㪥㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪘㫄㫆㫌㫅㫋㫊㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫋㪿㪼㩷㫍㪸㫅㪼㩷
㪓㪪㫋㪸㫋㪼㩷㫆㪽㩷㫍㪸㫅㪼㩷㫋㫀㫇㪕
㪣㫆㪸㪻
㪈
㪉
㪛㪣㪚㪄㪪㫀
㪥㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪪㫇㪼㪺㫀㪸㫃㩷㪺㪸㫊㫋㩷㫀㫉㫆㫅
㪧㪘㪞
㪤㪸㫏㫀㫄㫌㫄㩷㫃㫆㪸㪻㩷㫆㪽㩷㪚㪦㪉
㫉㪼㪽㫉㫀㪾㪼㫉㪸㫅㫋㩿㪺㫆㫅㫊㫋㪸㫅㫋㪀
㪇㪅㪍㫄㪆㫊
㪓㪪㫋㪸㫋㪼㩷㫆㪽㩷㫍㪸㫅㪼㩷㫋㫀㫇㪕
㪛㪣㪚㪄㪪㫀㩷㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪫㪿㪼㩷㪺㫆㫅㫋㪸㪺㫋㩷㫇㫉㪼㫊㫊㫌㫉㪼
㫆㪽㩷㪸㫉㪼㪸㩷㪺㫆㫅㪸㪺㫋㩷㫀㫊㩷㫃㫆㫎
㪇
㪇㪅㪉
㪇㪅㪋
㪇㪅㪍
㪇㪅㪏
㪈
㪈㪅㪉
㪩㪸㫋㫀㫆㩷㫆㪽㩷㫋㪼㫊㫋㩷㫋㫀㫄㪼
㩷㩷㩷
㪝㫀㪾㪅 㪈㪎 㪮㪼㪸㫉㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫋㪿㪼㩷㫍㪸㫅㪼㩷㫀㫅㩷㫎㪼㪸㫉㩷㫋㪼㫊㫋㫊
International Compressor Engineering Conference at Purdue, July 14-17, 2008
1166, Page 7
Figure 18 shows the relationship of the contact pressure ratio between the vane tip and the periphery of the rolling
piston, and the velocity ratio of the vane wear progression. The velocity of the wear progression is defined by the
amount of wear with the equivalent time.
From Figure 18, it is clear that in both the nitrided vane and the DLC-Si coated vane, there is contact pressure
where the velocity of vane wear, increases sharply, and this contact pressures varies as shown by the material of the
vanes. Contact pressure where the progression velocity of the vane wear increases sharply is defined as contact
pressure of wear-out limit. The contact pressure of the wear-out limit of DLC-Si coated vane is about two times
higher than that of the nitrided vane under the sliding conditions of CO2 refrigerant.
In the case of using the nitrided vane with CO2 refrigerant, the contact pressure wear-out limit is lower than the
maximum contact pressure in practical use. However in the case of using the DLC-Si coated vane with CO2
refrigerant, the contact pressure of the wear-out limit is higher than the maximum contact pressure in practical use.
Therefore we are able to achieve a significant level we call “WEAR-LESS” durability with all the conditions of CO2
refrigerant by coating DLC-Si to the vane.
㪫㪿㪼㩷㫎㪼㪸㫉㩷㫃㫀㫄㫀㫋㩷㫆㪽㩷㪛
㪛 㪣㪚㪄㪪㫀 㩷 㪺㫆㪸 㫋㪼㪻㩷 㫍 㪸 㫅㪼
㩿㪚㪦㪉㩷㫉㪼㪽㫉㫀㪾㪼㫉㪸㫅㫋㪀
㪫㪿㪼㩷㫄㪸㫏㫀㫄㪸㫄㩷㫃㫆㪸㪻
㩿㪚㪦㪉㩷㫉㪼㪽㫉㫀㪾㪼㫉㪸㫅㫋㪀
㪫㪿㪼㩷㫍㪼㫃㫆㪺㫀㫋㫐㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫋㪿㪼㩷㫍㪸㫅㪼
㩷㫎㪼㪸㫉㩷㫇㫉㫆㪾㫉㪼㫊㫊
㪫㪿㪼㩷㫎㪼㪸㫉㩷㫃㫀㫄㫀㫋㩷㫆㪽㩷䌮
䌮 䌩䌴䌲 䌩䌤䌥 䌤㩷 㫍 㪸 㫅㪼
㩿㪚㪦㪉㩷㫉㪼㪽㫉㫀㪾㪼㫉㪸㫅㫋㪀
䂥㪥㫀㫋㫉㫀㪻㪼㪻㩷㫍㪸㫅㪼
䃂㪛㪣㪚㪄㪪㫀㩷㪺㫆㪸㫋㪼㪻㩷㫍㪸㫅㪼
㪇㪅㪇
㪈㪅㪇
㪉㪅㪇
㪊㪅㪇
㪋㪅㪇
㪩㪸㫋㫀㫆㩷㫆㪽㩷㪺㫆㫅㫋㪸㪺㫋㩷㫇㫉㪼㫊㫊㫌㫉㪼
㪝㫀㪾㪅 㪈㪏 㪫㪿㪼㩷㫉㪼㫃㪸㫋㫀㫆㫅㫊㪿㫀㫇㩷㪹㪼㫋㫎㪼㪼㫅㩷㫋㪿㪼㩷㪺㫆㫅㫋㪸㪺㫋㩷㫇㫉㪼㫊㫊㫌㫉㪼㩷㫉㪸㫋㫀㫆
㪸㫅㪻㩷㫎㪼㪸㫉㩷㫍㪼㫃㫆㪺㫀㫋㫐㩷㫉㪸㫋㫀㫆㩷㫆㪽㩷㫋㪿㪼㩷㫍㪸㫅㪼
5. CONCLUSION
We were able to achieve a significant level of durability we call “WEAR-LESS”, by coating DLC-Si to the vane,
and we have developed a new CO2 compressor with a single rotary mechanism. In applying DLC-Si for practical use
of the vane, we optimized the silicon content in the DLC-Si film and secured the adhesion strength of the film. By
using the technology of coating DLC-Si to the vane, we were able to apply it to use in other products with harsh
sliding portions. We believe this application will contribute to the development of the new products.
REFERENCE
[1] Hideaki Maeyama, Tetsuhide Yokoyama, Hideto Nakao, 2006, Development of the Compressor for CO2 heat
pump with the single rotary mechanism, Proceedings of the 2006 International Compressor Engineering
Conference at Purdue: C056
[2] Hideto Nakao, Naotaka Hattori, 2007, Wear-Reducing Technologies for Rotary Compressors Using CO2
refrigerant, Proceedings of the 2007 Mitsubishi Electric ADVANCE December 2007: p.13-16.
[3] Hideaki Maeyama, Shinichi Takahashi, 2007, Rotary Compressor for a CO2 Heat Pump water Heater,
Proceedings of the 2007 Mitsubishi Electric ADVANCE December 2007: p.9-12.
International Compressor Engineering Conference at Purdue, July 14-17, 2008