CA1044145A - Pressure lubrication to apex corner seal - Google Patents

Abstract

PRESSURE LUBRICATION TO APEX CORNER SEAL

ABSTRACT OF THE DISCLOSURE:
A rotary internal combustion engine of the wankel type is disclosed. The engine has at least one epitrochoid chamber with flat side walls and an associated triangulated rotor cooperatively defining a plurality of variable volume chambers. An oil metering apparatus is integrated into the rotor for directing a jet of oil, preferably fed from a high pressure supply, against the side walls of the housing. The apparatus employs a biased plunger to distribute a controlled oil film about the housing side walls in cooperation with the eccentric path of the selected plunger location, preferably remote and independent from the dynamic seal grid system. The oil film is pumped by action of arcuate or annular side seal strips to migrate and coat intermetallic contact surfaces of the variable volume chambers. Oil consumption is reduced while providing a functional film at predetermined locations.

Description

The present invention is directed to lubrication of apex corner seals.
Both reciprocating engine piston rings and rotary engine rotor seals must be lubricated to prevent scoring. Both rely on gas pressure to form a seal with the opposing surface and both are also spring loaded to insure contact at all times. However, the top compression ring in a reciprocating engine is backed up by another ring which is intended to trap blow-by gases that manage to leak pass; even the oil control ring makes a contribu-tion to gas sealing in the reciprocating engine. As a result, the reciprocating engine has the benefit o~ a three-stage gas sealing system, which is not feasible in the rotary engine. The rotary engine can have only one seal at the various points that it must '~ .

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1 i ma]ce an effectivc scal; apcx scals, sidc seals and corner

2 ; scals cannot be backed up by a sccond line of ~,cals. 5 :

3 l~ Therefore, the nccessity for an adc~uate and controlled amount j of lubrication -to assist and promo~c a good sealin~ function 5 i at each of the mechanical scals i.3 of utmost importance. f 6 i The prior art proccss of lubricatiny the ~JaSi sealing 7 1- elcments of a rotary enginc has becn Eundamentally of two 8 ¦I types: (a) external metering to m:Lxturc addecl for combustion, 9 ¦l and (b) oil premixed with the fuel. ~arly commcrcial typc 10 i rotary cn~inefs have utilized oil prcmixcd with thc fuel and ~ have uscd proportions of arfproximately 50:1 or lOO~ ctually i 12 i thcre was little need to mix oil with thc fuel, bcfcause the 13 I rotors wcre cooled by internal oil flow and therc was con-14 1l 5iderablc oil lea]cage from thc rotor WhiCll seemcd to be i sufficient for lubricatin~ thc seals in the wor]cing surface. f , ,.: .
lG I Despite the prcsence of lubricating oil, a symmetrical wear 17 I of the apex seal tips occurred and chatter mar]cs appeared on l~ I the trochoid chamber wall. Seal tip wear is first and fo~rcmost ¦

19 I a maktcr of material capability, but it was determined by I extensive research that material capability did in fact exist. ¦

21 Therefore, the problcm related to an inadequate lubricatin~

22 film maintained under all conditions of opcration and under 23 a fuIl cycle a.s the rotor moved past various stations of the 24 ~ epitrochoid surface. Obviously, reasonable seal life cannot I be expected without lubrication of the high speed metal-to-26 ¦ metal interaces. The oil fuel mixture method would have 27 ~ wor]ced if the nccessary amount of oil had not been in constant 2~ I proportion to the fuel flow. ~ccordin~ly, this method has 29 ¦ been rejectcd as unsuitable for modern automobilc engines.

¦ The second method has bcen developcd to a commercial degree, however, by supplying thc necessary amount of oil to : .; , ~f~

the intake port according to engine operating conditions.
This method is not entirely satisfactory since it provides an excessive amount of oil which becomes waste in undue amounts as it is burned by the engine. There is little assurance that the oil film will be at all times at the points required for th~ metal-to--metal surface sealing.
It has been suggested by some authors, represen-tative ~f the prior art, that an autom~tic metering of lubricating oil from the rotor side might be feasible.
This has not been developed satis~actorily or implemented ~-by the prior art since it was thought that this approach would require a separate metering pump and by the likeli-hood of in~erruption of the sealing elements by necessary limitations of introducing the oilO
The problem, therefore, still remains as to how .-;
to provide an efficient, low cost oil lubricating system for the various dynamic ~ealing stations o~ rotary engine, the system being desirably self-metering and will provide preaisely the right amount of oil at the right locations, neither too much~nor too little.
~ In accordance with the present invention, there - i~
; ~ ~ is provided for use in a rotary internal com~ustion engine having a housin~ provided with a peripheral wall and opposed side walls, a rotor carried within the housing or pl~net~ry movement and having an axis of movement, ~;~ the combination comprising: (a~ sealing elements carried by the engine for providing a dynami~ gas-tight seal between the rotor and the peripheral wall and side walls, the elements cooperating to complete a plurality of variable volume chambers between the rotor and housing; and ~b~
lubrication means carried symmetrically by the rotor with i ~ 3 ~
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respect to a radial plane bisecting the rotor, the lubri-cation means directing a supply of oil toward and eccen~rically onto the opposed side walls for promoting a thinly controlled smeared film of lubricant across the variable volume chambers.
The combination provided in accordance with this invention is effective to distribute lubricating oil in the form of a thin smeared film between the side housing lQ walls and rotor in such a way as to result in a predetermined and precisely co~trolled supply of oil at ) the reguired sealing interfaces.
The invention is described further, by way of illustration, with reference to the acco~panying drawings, in which:
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Figure l is a fragmentary view of the rotor and adjacent trochoid wall for a rotor internal combustion `
engine; said view being an elev~tion of the fragmentary structure of Figuxe 2;
Figure 2 is a sectional view of a rotcr and rotary engine housing embodying the principles of this invention; - ~ ;
Figures 3 and 4 are views respectively similar - , to Figures 1 and 2, but illustrating an alternative embodiment. -Figures 5 and 6 are again views respectively ;
similar to ~igures 1 and 2, but illustrating still another aIternative embodiment.
Figures 7 and 8, respectively, are three . ,:
dimensional graphs comparing oil economy for a ro~ary ~ -engine equippéd with prior art oil metering and a rotary : ', ~' ' .

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engine equipped with oil metering of this invention.
Turning first to Figures 1 and 2, a preferred embodiment is shown. The apparatus is useful in generating a controlled lubricant film along the opposed housing side walls; the film acts as a source of lubricant for coating ;
the various dynamic sealing elements, such as a seal grid system 15 carried by the rotor. A typical rotary internal combustion engine has a principal chamber defined by opposed side walls 10 and 11 of the housing and delimited peripherally by a wall 12 preferably formed with an epi-trochoid configuration. A rotor 13 is mounted for plane-tary movement within the chamber defined by said walls and has flat sides ~ and 9 arranged adjacent and parallel to the walls 10 and 11 of the chamber and has a triangulated outer periphery 25; a bearing 14 supports the inner surface of the rotor upon an eccentric carried by an eccentric -shaft of the engine (not shown).
The seal grid system 15, carried by the rotor, is effective to dynamlcally seal between the rotor and walls 1 20 of said principal chamber to define a plurality of variable ,1 volume chambers such as 24. Th~ seal grid system may '~ comprise a sealing strip 18 carried in a slot 21 at the -~
apices of ~he triangulated rotor, a cylindrical corner or end button seal 19 i~ carried adja ent the extreme ends of the~stxip 18 for sealing bet~een the ends of the strip and the opposed side walls of the chamber. Arcuate side sealing strips, such as ` . . : - . ...
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1 lG and 17, cxtcnd betwccn thc cylindrical corncr button seals 2 l, 19 to completc said dynamic gas-tigllt scal grid which divides ~ ;
3 the spaco cntrained by the outer portion of thc rotor and the ~I chamhcr walls into said plurality oE varia]~l~ volumc chambcrs.
5 ¦I The rotor turns as shown by arrow in Figurcs 1, 3 and 5.
G l A primary oil cooliny circuit i~ typically cmp,loyod 7 l~ to conduct oil to the rotor; hi.gh pressure oil is jcttecl to ~I, an opening along onc sic1c o~ thc intcrior peripllcry (nok shown) ~"' and i5 scoopcd by a structure on thc interior of thc rotor ~;
10 I to fling such oil throughout the interior of thc hollow rotor, particularly against the radially outer wall of the rotor ~or 12 l3 coolin~ the apcx seal assembly. .Such oil cooling circuit is 13 1! supplicd with high pressure oil ~rom a suitable source, but 1~ , ]~ecomes low prossure when jctted into the interior of thc 15 ! rotor~ A pair of concentric oil rings 39 and 40 are disposed lC,3 in complimentary groovcs in thc sides of thc rotor and are 17 ~ a~aptcd to retain thc flood of high pressure oil which resides lU radlally inwardly thereof; SUCll oil rings operate against the 19 side walls 11 and 10 of the hou~ing.
~s shown in Figures, 1 and 2, the lubrication means 3, 21 30~ for impartin~ a controlled and self-metering oil film to 22 ¦ thc sidc walls 10 and 11 and the variou~5 dynamic scal clements 23 carried by thc rotor, is locatcd remotely and independently.
2a Such lubricatlon means 30 compriscs a cylindrical plunger 41 ~ at each side of the rotor and is slidably disposed in a 26 oompllmentary shaped cylindrical bore 42 extendin~ parallel to 27 the axis o the rotor and remote from the sealing grid system.
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2a ~ ~he plungers are arranged symmetrically with respac~ to a 29 ccnter plane 50 of the rotor and eacll have a rcccs~ 3~, in its -~ outcr ~ace adjacent a respectivc side wall of the rotor 1 31 housing. Such r~cess or rescrvoir is supplied witll oil by a i : : : .

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1 ~I path which includes an opcning 31 in the rotor bearing 14 2 1 in communication with the hi~h pr~ssure oil system carried 3 i tllrouc3h thc ecccntric shaft. Tlle openi1lg 31 communicates 4 with passage 32 e~tending to thc midsection o~ the plunger.
5 j, ~n annular groove 35 in thc cy]indrical periphery of the 6 li plun~er communicates with passagc 32 and al50 communicates with

7 ~l a passage 33 ext~nding parallel to the lcnyth of thc plunger 3 11 leading to recess 3g. ~nother passage 34 cxtends parallcl to 9 ¦ the center line of the plun~er and communicates recoss 3 10 ~I with bore 36 in the opposite end of the plunger. The bore 3 11 '' has a helical spring ~3 effcctive to apply a resilient force 12 ~ against the plunger to urge thc annular fac~ 51 of the plung~r 13 ¦~ against the respective side wall (10 or 11). The bore 36 i5 14 1l in communication with the intcrior of the rotor by way of 15 1', passage 37, thcreby allowiny oll exitin~ from reservoir or 16 ~ recess 38 to entcr the low prc6sure oil ~allery in the rotor. ~ ,' 17 I In operation, a higll pressure source of lubricating 1~ I oil is received through openin~ 31 an~ passages 32 and 33 19 I to fill the reservoir or rece~s 3~. I-Iowever, the rcservoir 20 1¦ 3~ will be at a relatively low pressure because of the 21 ~ communication through passages 3~, bore 36 and 37, with the 22 , interior of the rotor which is at a low oil pressure level. ' 23 The,exposed body of oil in recess 3~ i5 carried along a , -24~ variable or irregular path against the respective housing ~side wall by virtue o the planetary movement of the rotor. ,~
26 The eccentric path serves to expose the deposited oil film to 27 the working chamber of the engine as the rotor advances; the ' ~ ~, 2~ film can then migrate to lubricate the seal grid and epitrochoid 2~ wall with a decrease in oil lost through combustion. The annular end face 51 of each plunger will, by virtue of its ~' :~ '" ' ~ '' , -7- ,;, -,~, , I . ~
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~ll spring bias against the sicle wall, reducc the supply of oil 2 ~ to a predetermined thin oil fil~. Thc oil ~ilm will miyrate 3 as the siclc sealing strips 17 come in contact with the oil 4 ~ durin~ tlleir eccentric patll over the side housillg surEaces 10, 5 , and 11, and will be pumped by action of the side 5caling strips/
G i.e. 1~ and 17, into the variable volume chambers 2~ ~or supply-7 ~ ing a limited and appropriate amount of lubricant to coat the 3 ¦~ apox seal strip~ 18 as well as the cylindrical corner soals 19.
9 ¦I The side sealing strips 17 promote a pumping action due to the 10 il eccentric motion of tlle rotor. No separate oil pump is nec-11 l¦ essary for the lubrication means 30.
i 12 '¦ The increase in oil economy resulting from this ;l 13 I invention i5 rather direct when Figures 7 and ~ are viewed.
14 ¦I Figure 7 illustrates the oil economy in terms of miles per ~, 15 ~! quart of oil realized while oporatiny with a conventional 16 1 prior art seal grid system and a conventional oil system 17 j whercby lubricant is supplied as a mixture metered to the -~
18 ~ induction system. Fi~ure 7 is a three-dimensional block 19 ll diagram showing induction ~ystem pressure in terms of inches per 20 !I mercury plotted along one of the base lines, r.p.m. of the 21 1l engine plotted along another of the base lines, and oil economy 22 l¦ in terms of miles pcr quart is plottecl along tho vertical : !~ : ` : -23 i; dimension. Fi~ure 7 represents relatively poor oil economy 2~ j ;and is that realized by a commercially av~ilable mode. ~t 25 ! 12 inches of mercury (high pressure) and a low r.p.m., oil ~ consumption reaches as high as 2,400 miles per quart. This l; ~ 27 is its maximum oil economy and all other combinations of ~ pressurc and speed rosult in much lower oil economy.

`j ~ 29 In Fi~ure ~, oil economy is plotted usin~ the present invention. Maximum or peak oil economy is realized a~

~; 31 somcwhero aroun~ 10 inches of mercury at a speed o~
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1 l approximately 3,200 r.p.m.; a major portion of the various 2 11 other comblnations retain hi~h oil econon~y in exces5 of that 3 ¦~ realized by the prior art construction. Only in thc limited 4 ~ combinations of low prcssure and hicJh speeds, is oil economy 5 l¦ som~what similar.
6 ll With tho use of the structure of the pre~erred mode, 7 j the oil economy 5hould bc at least e(lual to that of the ¦~ rcciprocatincJ enyine (which obtains approximately 2000 miles i pcr quart) under all combinations of pr~ssurc and spoed.
' ~rior art rotary internal eombustion engine constructions, 11 ¦ sueh as shown in Figur~ 7, have obtained approximatcly 800-12 ¦~ 900 miles per q~lart. It i5 expected that some of the oil ' ~ 13 ¦ lubrieant will be eonsumed in the rotary eombustion proeess ¦ and there~ore thc theoretieal optimum of 5000 miles per quart i ~S ¦ eannot be praetically obtained in a rotary internal eombustion ~-16 ¦ engine. Ilowever, by use of the self-meterincJ pluncJer meehanism ~ ~ -17 of this invention, a mueh greater oil economy results in a higher perLormance ~or the senl grid system is obtained and is 19 I in exei_ss of 1000 miles per quart.
~ n alternntive e~.~bodlment i5 lllustrated in Figures ~21~; ~ 3;and 4O IIere tha lubrieatlon means is ineorporate~
22~ intec3rally with the eorner seal or eylindrieal button 60. Low 23~ ~press~ure oil is reaeived from that whleh is clreulating within ~the~interior of the rotor and is eommunieated by way o~ a 25~ ~ eentral drilled passa~3e 62 en~ering upon a semi-eireular 26~ ~ re~cess;61 in the end ~acc of the eorner seal 60. The eorner 27 ~seal lS stepped in eonfiguration for ~itting within a st~pped 2~ ~bore 63 in each side of the rotor; the stepped bore has a :Z9 1 ! ~fi~st~portion 63a whieh i5 adapte~ to reeeive tlle neek 60a of ;
30 1 the~eorner button and has an enlarc3ed portion 63~ for 31 1 reeeivinc3 the outer e~posed portion of the sealin~ button.
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_ nnular seal rin~s 6~ and 65 fit within annular grooves on 2 j each of the resp~ctivc stepl~ed portions ~0 and GOa; seal 3 ring 64 has a deviated portion G~a to accommodate the inter-~ ~¦ position of slot 71. ~lthough not shown, springs bias the 5 1I buttons GO into engagcmont with the housing side walls. Oil 6 1! is directedr by way of the location of the rescrvoir or rec~ss 7 ~ 61, to the housing side walls at a location immediat~ly ! beneath and adjacent the slot 71 containing the apex seal 9 I strips 70. This reduces, somewhat, control of thc side scal I arcuate strips 67 and ~ to pump a uniform film for dis-tribution to th¢ variable volumc chambers; there is a greater 12 I opportunity ~or the oil, distributed by thc reservoir, to 13 ¦ migrate past the corner seal button in an excessive or in a 14 ¦ deficient amount that i5 not self-me~ered continuously and 15 ¦ accurately, but opcrable. IIowcver, the oil supply to the lG ¦ recesses Gl requires lcss fabrication. The passage 62 serves 17 I as an input to recess ~1 at low oii pressures, thereby not 18 1 requiring a relief passage for return of oil to the oil gallery;
`~ 19 ~ note that oil is obtained close to the radially outermost ~
¦ section of the oil ya~llery whcre oil~will be urged b~ rotary 1-motion to enter passage 62.~
22 ~ ~ ~ The alternative mode of Figures 3 and 4 shows an 23 ~ end face 6~ which has a greater surface area for smearin~ and 2 ~ ~ effecting a thlnning out of the oil film exposed to the ;25~ ~interior~side walls of said engine. The lack of a high 2~6~ ~pressiure oil feed necessitates a greater contact surface for ~27~ mechanically spreading the oil film.
2~ ~ A second alternative embodiment is shown in Figures 29 ~ 5 and 6 and is a hybrid of the structures of Figures 1 and 3, ~30 but additLonally incorporates an enlarged diamcter or the .'',~: -::`" i ~ -10-'': : I : .
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oil reservoir or recess 82 in the corner seal or button.
The use of a high pressure feed to the recess 82 is used with a return passage to the oil gallery; the oil metering ' ' ' is integrated as part o~ the corner seal and is not independent. In some particularity, the large diameter corner seals 80 have a stepped configuration where~y a neck 80a fits slidably within a stepped portion 81a of a complimentary bore. An enlarged portion 8Gb of the corner seal slidably fits within a larger stepped portion 81b of the bore, portion 80~ overlapping and surrounding a ' ' ~, portion of the ends of the apex seal slots 82. The j corner seals have a totally circular and ~nlarged recess ~ ' :
82 which is fed with high pressure oil by way of a series of~passages: 83 extending along the centerline of the ~-' corner seal,~ radiating passage 84 communicating by way of '~
passage 85 with the high pressure oil supply at the rotor '"
bearing 86. The other radiating passage 87 commNnicates ' with an angled passage 88, together serving as a retllrn of '~
oil to the oil ga31ery. Each stepped corner seal button . ~-' is biased by a sprlng~8g extending~between~a centering journal on~the interior~ of the stepped button and~the ~ i, opposite~side'of the~interior of the rotor. Again, the side aeal or~compression strips 9l and 92~ as shown, conneot ''~
wi~h the corner seal-button'and in a manner in which to '~
provide ef~ectivé sealing with the rotor rotating in the direct~on ~s shown by'the arrow of Figure 5.

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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. For use in a rotary internal combustion engine having a housing provided with a peripheral wall and opposed side walls, a rotor carried within said housing for planetary movement and having an axis of movement, the combination comprising:
(a) sealing elements carried by said engine for providing a dynamic gas-tight seal between said rotor and said peripheral wall and side walls, said elements cooper-ating to complete a plurality of variable volume chambers between said rotor and housing; and (b) lubrication means carried symmetrically by said rotor with respect to a radial plane bisecting said rotor, said lubrication means directing a supply of oil toward and eccentrically onto said opposed side walls for promoting a thinly controlled smeared film of lubricant across said variable volume chambers.

2. The combination of claim 1, wherein said lubrication means comprises a spring biased plunger carry-ing a shallow reservoir of low pressure oil adjacent each of said opposed side housing walls, said plunger being;
effective to smear said oil upon said opposed side housing walls in a thinly controlled film.

3. The combination of claim 2, wherein said engine has another lubricating circuit effective to supply oil to an interior gallery of said rotor, said rotor having means for scooping oil supplied to a radially inner portion thereof and flinging said oil radially outwardly along the interior of said rotor as part of said another lubricating circuit, said lubrication means being supplied with high pressure oil from said another lubricating circuit and having passages for separately conducting oil to said plunger reservoir, said plunger having means to circulate a portion of the oil received from said lubricating means back to another lubricating circuit.

4. The combination of claim 1, wherein said rotor is triangulated and said elements comprise seal strips carried at the apices of said rotor, corner seal buttons carried at the ends and surrounding the ends of said seal strips, and arcuate side sealing strips extending between, said corner seal buttons, said lubrication means having a plunger biased to carry an oil reservoir adjacent said opposed side walls, said plunger being located remote from said elements, and having means to smear said lubricant film in a manner to supply a sufficient quantity of lubricant film about each of said elements during operation of said engine.

5. The combination of claim 1, wherein said lubricating means is additionally symmetrical about said axis of said rotor.