Abe, K.

Machida, H.

Matsumura, N.

English

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Purdue UniversityPurdue e-PubsInternational Compressor Engineering Conference School of Mechanical Engineering1990An Experimental Study on the Dynamic Behaviorof Micron-Size Gap by Cylinder Pressure andTemperature Under the Rotary CompressorOperationN. MatsumuraMitsubishi Heavy IndustriesK. AbeMitsubishi Heavy IndustriesH. MachidaMitsubishi Heavy IndustriesFollow this and additional works at: https://docs.lib.purdue.edu/icecThis document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu foradditional information.Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at https://engineering.purdue.edu/Herrick/Events/orderlit.htmlMatsumura, N.; Abe, K.; and Machida, H., "An Experimental Study on the Dynamic Behavior of Micron-Size Gap by CylinderPressure and Temperature Under the Rotary Compressor Operation" (1990). International Compressor Engineering Conference. Paper779.https://docs.lib.purdue.edu/icec/779r I fl. E ~\ E\PERI~£\T~L STLDY 0\ THE DY~~,IC BEH~VIOR OF ,lCRO\-~IZE GAP B\ CXLI\DER PRESS~RE ~\D TE,PER~TCRE [~DEk THE ROTARY C01PRES50R OPERHIO\ -1CTHORS ~ORlAKl MATSl~~RA * KIYOSHI ABE * HIROSHI ,ACH!DA ~* ~ \AGOYA RESEARCH & DEVELOP,ENT CE~TER ,ITSUBlSHI HEAVY INDUSTRIES, LTD. NAGOY4, JAN~ ilR-CONDITJON!NG & REFRIGERATlO~ ~4CHlNERt WORKS ~lTSUBISHl HEAVY INDUSTRIES, LTD. AICHI. JAP-1~ ABSTRACT is for recent heat pump air conditioners, compressors are requir~d to possess higher efficiency and higher reliability. Since a rotary compressor has several gaps in the order of microns hhirh affect its efficiency and reliability, it is necessary tu understand tl!., micron-siz!Ol gap under the operation. Hohever, since the compressor is small, the installation of a sensor is difficult. and since the temperature and pressure conditions are sevP.re in u,., r.ofrigerant and oil environment, a measurement error is large due to L•'mpcro ture drift, and therefore an advanced sensor is needed for detailed measure ment of gap. fhis paper descr1bes the compact size and low temperature drift edd~ current type gap sensor which we developed, and an experimental stud} on t!iQ ~ynnmic behavior of micron-size gap cau~ed by cylinder pressure and t~mpero tur~ under the rotary compressor operation. INTRODUCTION Recently a rotary compressor for heat pumps is required to possess high per· formilnce. A rotary compressor has several gaps in the order of microns hhich affect its performance. These gaps consist of various parts such a> r:; I inder b~arrnrl- rotor, blade, and the I ike. Th~se micron-size gaps can change according to the deformation cau5•J h; acsembling and the pressure as well as the temperature under th• •JmfJ· ressor operation. The siZP of gap under the compressor operation can be diff~rPnl fro• ~ ;.al u~ hhich tS dssumed b) single components. ff th~ !il7t2 <..·f gCi~' i :~ l.Jr.t;..:o: 845 thJn th~ assum~d •alue. it !~ads to lower performance b~ compression gas lea•. l f th-e oiz~ uf gap is smaller thon the assumed 1alu~, it !~ad" to lcll-er perfomance b; increasing mechJnical loss. J t IS f~~uired to understand the micron· size gap under the Compr<"'550r O~•'ro· t1on to precent such disadvantages. Th~ meosurement of such micron-size gap requires a sensor which assures dccurac~ of several microns. The gap sensors on the market can not meet such accuracy under the compressor operation. There are various sensors such as a inductive type (eddy current typt>l, capasi ti•e type, a ultrasonic type, a optic type to measure a gap in the order of microns. There are refrigerant and oil in a gap. The character· istic of a sensor should not be affected by refrigerant and oil. The sensor hhirh can mdet such requirements is presumably a edd~ current type sensor. This paper describes the eddy current type gap sensor which we developed. lt is compact, and have lo~o temperature drift and heat proof. The paper <dsu describes the dynamic behavior of micron-si2e gap under the rotary compressor vPera tion. EDDY CURRENT TYPE GAP SENSOR \o commercial gap sensors can satisfy requirements in size, heat proof, and m~asuring accuracy. In order to measure the micron·size gap under the compr~ s5or operation"" need the sensor which is compact (dia.S mm or less), and ha•~ h~at proof (200"C or more) and lower temperature drift CO.l.um/'t or less). tp_rotot•pe sensor and measuring equipment The prototype sensor is shown in Fig.l, which comprises a bobbin an ~h1ch ,·oil ~ire is ;,ound and adhesive with which the coil ;,ire is fixed to tile bobbin. ~aterial of the bobbin and the adhesive is ceramics because it hos heat proof and lo~er deformation by heat. Coated copp~r hire ;,ith higher heat proof was used. The copper wire of 60.um india· meter has ~ound about 40 turns on the bobbin. Characteristics of sensor b~ calculating given by the difference of the coil shape are sho;,n ir Fig. 2. {reference(lJ, (2).) As the ratio of D-d in the coil beco01es larger. the sensitivity ;,ill incease. The ratio;:.,4of D·d was set to about 0.3 in the prototype sensor. It is required to minimi~\ the influence b} ch.;nge in resi~tance of coil ~ire to reduc.e temperature drift. Elenri•.al equipment is a bridge circuit to minimize temperature drift. Th~re ar~ a CC'i 1 for measurement and for t.;mperature compensation on thE' circuit. T~~ protot;pf sensor ;,as designed to minimiz~ the me~suring error causo·d ~Y 846 Jn~•~nnPss oi ~emp,rature of the sensors for the temperature compensaticn an.J for m~asurc:m~n L. There <ore " coi I for measurement and fvr t~mp .. rH Lure c.umpt'nSdtion on the same bobbin ~s ::lio~n in Fig. 1. Th~ medsuring circuit is slio~n in Fig. 3, which is composed nf briJi• circuit. osCillator, Ph<ose detector, filter and amplifier. lhP bridge circui L comprising coils for temperature compensatiun and m~asurernent is provided to cancel the influence by temperature, but i l is eery hard to prouide a coil with such characteristics as meeting the require ments thoroughly. Thus further temperature compensation ~as conducted usin~ the phase detection circuit for a little amount remained not to be compftn· sat~d b) the sensors for temperature compensation and measurement. G~PS ~T EACH PORTION OF COMPRESSOR The rolling piston type compressor for heat pumps is shown in Fig. 4. , compression part is composed of cylinder, rotor, blade, upper bearing and lu~~r bearing, in which different micron-size gaps are formed. SuLh micron-size gaps are shown in Table 1. These gaps are formed in the compression part. and other gaps are also Juund bet~een a shaft and upper or lower bearings, The influence of these 1•1 on performance and reliability of the compressor is significant. For exampl~­if the gap B is larger, compressed gas ~ill flow into the suction side throui~ the gap. If it is smaller to the contrary, it causes lower reliability due to a bno rma I wear as we II as 1 ower COP due to increase in I oss power. EXPERIMENTAL METHOD S~veral gap sensors were mounted in rotary compressor ~ith 17cc in -displacement to measure the gaps A and B shown in Table 1. The position •here gap sensors were mounted is shown in Fig. 5. The gap A is that b;ot-'"'en the blade and the b I a de guide groove. Two sensors ~ere mounted at th~ C)linder to measure the gap from the both sides of the blade guide .roo~e. The total value given by the sensor 1 and the sensor 2 correspond• to the gap bet~een the blade and the blade guide groove. The gap B is that bet~een the rotor and the cylinder. and two s~nsors ~clre mour.ted at the cylinder. ~s the sensor was mounted at th" c:yl ind-er, the gap 8 formed during rotation of a turn ~as not given but onl) th•· gap of rutdional onele at the position of the sensor mounted ~as measur•·d. Th~ blade movement ~as also measured on the bose of rotRlJOnal angl~. Tht: t~i'lp~rdt\Jt 1: control \t.oSS performed to tile signal proressing part ~~r~mp rl~.lni: th'=' bridge ~.:ircui l and Lhe phase dfltector etc. on tl1~ s~m-t; T.t""mPt'-:'"i 847 ture at the calibration and higher accuracy was given. An example of the check results of gap characteristic and temperature characteristic for the sensor 1 is shown in Fig. 6 and Fig. 7. The output change of 3mV per 1 .u m in gap is shown, and very low value of 5 .u m approx. in temperature drift is given be tween the roo"' temperature and 120t. When the behavior was measured, temperature compensation was conducted by the temperature measured by a thermocouple integrated with the sensor. Other factors of error are unevenness of electrical characteristics of the blade and the rotor faces. Since the position of the blade where the measurement was made by the gap sensor changes during rotation of a turn, any unevenness of the electrical characteristics at such place cause measuring error. Fig. 8 shows t~e output change of the sensor when the blade is caused to rotate a turn. As the value in Fig. 8 is the total of those by the sensor 1 and the sensor 2, the value should be constant unless any unevenness of the electrical characteristics. The total output value of the sensor 1 and the sensor 2 shown in fig. 8 is bigger about by 2 .u• around the portion at 180 degrees in rotational angle. It seems the cause is due to unevenness of the electrical characteristics of the measured blade face. The gap measured bet-~een the blade and blade guide groove was corrected by the value in Fig. 8 The surface of the rotor shall be •easured similarly by the sensor when the gap between the rotor and the cylinder is measured. The change in out-put occurred when the rotor is caused to rotate a turn is about 2 .u m. Since the rotor is turning under the operation, the correction is un-available and about 2 .u• of 11easuring error may be inevitable as maximu11. THE DYNAMIC BEHAVIOR OF GAP.UNDER THE COMPRESSOR OPERATION Fig. 9 shows the dynamic behavior of gaps at each portion under the operation. A1 is the data measured by the sensor 1. A2 is the data measured by the sensor 2, and A1tA2 is the total value of Al and A2 showing the gap between the blade and the blade guide groove. Bl is the data measured by the sensor 3, and B2 is the data measured by the sensor 4. The values of Bland 82 show the gap between the rotor and the cylinder at a certain angle. Gap between blade and blade guide groove (1) The gap between the blade and the guide groove is about half in value of that assumed by single components, and the gap fluctuation during rotation of a turn is clarified. The reason why the gap is about half of the assumed value is supposed to be deformation caused by assembling, 848 cylinder pressure and heat. (2) The c~use for the change in gap during rotation of a turn seems to be deformation of the blade guide groov-e by cylinder pressure. The maximum gap is occured at the rotational angle of 340 degrees approx., and the gap becomes smaller between 340 to 10 degrees. And then the gap is gradually increasing. It appears the deformation is encouraged by the pressure within the blade guide groove. (3) MaKimum value of the gap between the blade and the blade guide groove with the difference of pressure between discharge and suction pressure is shown in Fig. 10. As the difference of pressure increases, the mamiKmum value of gap becomes larger. Behavior of gap between rotor and cylinder (1) The gap between the rotor and the cylinder under the operation is about half of that established when the compressor is assembled. Gap 82 is larger than gap Bl. (2) The gap between the rotor and the cylinder depends on the difference of pressure as shown in Fig.10 like the gap between the blade and the blade guide groove, and is supposed to be subJect to the deformation by the cylinder pressure. (3) Since the size of clearanace 82 is a little larger than that of clear-ance 81 when the compressor is opera ted in the state of air open, the cause for which is larger clearance 82 than that of Bl is due to the deformation by assembling not because of the deformation by pressure and heat under the operation. SUMMARY The gap sensor which is compact, heat proof and lower temperature drift has been developed to understand several gaps in the order of microns under the compressor operation. The gaps between the blade and the blade guide groove as well as that between the rotor and the cylinder were measured with the gap sensor developed. Respective gaps were found to be smaller than those pre-estimated, and it was understood that one of factors was deformation by the cylinder pressure. REFERENCES (1) C.V. Dodd & W.E. Deeds: ORNL Contract No.w-7405-eng-26('67) (2) Yamada & Ueda: EM-71-19 849 I 0 0 E "' <.> .. .. .., 95 .. "' "" ..!; t _,.----- Sobb in Adhesive agent Fig. 1 Sensor structure o.z o.• o.s Gap (mm) Fig. 2 CharacLerisLic or gnp sensor phase filter de tee tor ampiifier oscillator~------~ Fig. 3 Circuil. diagram 850 Rotor Cylinder Shaft Discharge Housin~ .,,,11~~~~~~~ Monor rotor stu Lor Shaft Lipper bearing Shaft pin A~Lor Cylinder AccumlaLor Discharge muffler Discharge valve Intake pipe Lower be uri ng Fig, 4 Compr~ssor sLruct"re 0. 3 Sqnsorl E D. 2 "' 2-"' 0 D. 1 20 40 Gap (,U) 60 Fig. 5 Installation of •ensors fig. 6 Characteristics of sensor! 20 Sensor! a to o~--~~----~----------~------0 f:O /00 Temprature ("C) Fig. 7 Charnctr.risLic• of temprature drift 851 k~~~~ " "' 3 "' .., > ..... ., ., .... .... Q " 0 !10 1 ao 27 0 ., "' ., .. Rotational angle (•) Fig. 8 CharDcteristics of drift 180 360 Rotational angle(•) Fig. 9 Behavior of gap " .= "' A2 " > 1.0 .= ... 9 0 me s ., "' "' ~ ,.. ., " 0. 5 ~-®-- -®-"' " c -® ___ ..1$>- $ ... "' lll " ...." "' "' " ., 0 " e; 0 1.0 1.5 2. 0 Q. the d i fie renee of l'ressure (MPa) "' "' Fig. I 0 Characteristic of the di ffercnc~ of pressure Table 1. Micron-size gaps in compressor Gap f\ Gap between blade and blade chnnnel within cylinder B Gap betw~en rotor and cylinder c Gap between upper bearing and r"otor D Gap between lower bearing and rotor E Gap between upper bearing and bl<ide F Gap between lower bearing and blade G Gap between rotor and shaft 852 

An Experimental Study on the Dynamic Behavior of Micron-Size Gap by Cylinder Pressure and Temperature Under the Rotary Compressor Operation

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An Experimental Study on the Dynamic Behavior of Micron-Size Gap by Cylinder Pressure and Temperature Under the Rotary Compressor Operation

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