US 2662516 A
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Description (OCR text may contain errors)
Dec. 15, 1953 A. G. BODI ,JR 2,662,516
PISTON F'O NTERNAL- ACOUS COMBU ON EN NES HAVING DETONATION SUPPRESS MEANS File 29, 1952 d Feb.
INVENTOR. 14 ear 6 Ecol/v5 Me.
Patented Dec. 15, 1953 PISTON FOR INTERNAL-COMBUSTION EN- v(muss HAVING ACOUSTIC DETONATION SUPPRESSION MEAN Albert G. Bodine, J r., Van Nuys, Calif,
' Application February 29, 1952, Serial No.
Claims. (Cl. 123-191) This invention relates generally to internal combustion engines and to means for suppressing irregular burning and detonation of fuel-air mixture therein. The invention is based on my discovery that detonation in combustion engines involves acoustic phenomena and can be alleviated by means of certain acoustic apparatus used in combination with the combustion chamher.
The present application is directed to improvements in the field covered by Patent No. 2,573,536, issued October 30, 1951,entitled Engine Detonation Control by Acoustic Methods and Apparatus. full discussion of the acoustic aspect of detonation in combustion, and my basic solution for controlling detonation in combustion, reference should be had to my said issued patent.
Only briefly stated herein, the present invention is based on the fact that detonation in an engine combustion'chamber produces sound Waves, a large part of which rise to high amplitude at resonant frequencies of the chamber, and on my discovery thatv the sound waves produce many of the various well-known and harmful manifestations of detonation. According to my basic invention, I inhibit or attenuate these harmf-ul effects by interfering with or attenuating the high amplitude, detonationeinduced sound waves, and this is done by use in connection with the combustion chamber of acoustic attenuation means made responsive to (operative at) the frequencies or wave lengths at which the detonationinduced sound waves build up to high amplitudes. One type of acoustic attenuation means broadly disclosed in my patent involved an attenuative configuration given to the upper end portion of the piston.
The general object of the present invention is the provision of an improved detonation controlling sound wave attenuator means of the class involving the piston structure.
Another object is the provision of a piston type of detonation attenuator which is improved as regards frequency response to and dissipation of the offensive sound wave frequencies encountered in combustion.
According to the present invention, there is formed around the piston, in the area between the upper ring grooves and the top of the piston, a deep groove which receives a slotted ring. The upper portion of the piston, above this ring and groove, has suificient clearance from the side wall of the cylinder to permit passage of detonation sound waves from the combustion chamber to the slotted ring, and these waves enter through cordance with of a piston in acshown inside the a slotted ring.
In the drawingsan engine cylinder is designated at 8, openinginto'combustion chamber 9,
chamber by attenuation.
The thickness of the ring 16, in the present design, is only about one-half the full depth of the groove l 5.
solid portion E9, the two portions groove IS. The slotted portion 20 is formed by cutting radial slots 2|, which in this instance are of approximately the same thick-- forward edges 23 of fins 22 are formed on an angle of approximately 15 with vertical, joining the outer surface of solid tom, and being offset gress of the sound waves from the clearance space I 8 into the slots the fins may be made parallel to the forward edges 23.
The annular groove space 30 behind the slotted ring [6 forms an acoustic cavity, and this cavity, in combination with the clearance space l8, vestibule 24, and ring slots 2|, forms a Helmholtz resonator. The space 30 is the cavity of such resonator, and the clearance space 118, vestibule 24, and ring slots form its restricted neck. Following ordinary techniques familiar in the science of acoustics, the acoustic wave frequency at which detonation is severe in mine in which the piston is to be used is first This frequency will be an acoustic resonant fre quency of the combustion chamber. The dimensions of the Helmholtz resonator are then made such as to be responsive, 1.4%., resonant. l0 detonation wave frequency.
It is known in acoustics that a Helmholtz resonator functions to attenuate a sound wave of the frequency to which .it is resonant. This .it does by reason of tbefaotthata sound wave hav- :ing a frequency corresponding to the resonant frequency of the resonator causes high velocity gas oscillation in the restricted V ck region of the oscillator, and high velocity 183s particles in the restricted neck re n sc ub aga nst one another, thereby developing substantial friction, which means that the driving sound wave loses substantial ener y.- .-.A s und wave can :be wery materially attenuated by this means.
The described Helmholtz resonator provided by the -present invention ,is-nuite effective in subduin detonation .by absorbin energy from the detonation sound wave The 2 0 .of the resenator, comprising the iclearanQQ 595. 6 :15, vestibule 24. and slots .21, :is irregu ar and discontinuous in both cross: tiona-nd direction, and .develops substantial frictional dissipation of the sound wave. as the cavity 30, there is a tendency tpward development .of sound; waves around the annulu Any tendency for such waves within .the chamber .30 results in furthersound .wave.dissipation,.since the annular sound walla conduit h mered by the inner edges of the fins 22,, whichcause reflections .all along the annulus. and consequent 2 deterioration.
It will be understood that the xdrawings and description areillustrative .only. and that various In an annular acoustic cavity, :such
changes in design, structure and arrangement may be made without departing from the inven-.- tion as defined by the appended claims.
1. For use with an internal combustion engine having a combustion chamber and a cylinder opening into said chamber, a piston adapted do: rec pro at on in sai c l der. s i piston hawing an upper end portion formed with a slightly set back outer side surface, so as to furnish a narrow sound wave passage between the QPPH end portion of the piston and the opposed wall of the cylinder wall, there being an annular groove said piston communicating with said sound wave passage, and a piston encircling ring in said groove, said ring being adapted for engagement with the cylinder wall, said groove being deeper than said ring, so as to afield an annular acoustic cavity behind said ring, and said ring having narrow sound wave passage heretbtes h t rov de re t i wav cemmn at en between s id sou wave passage ,angi said annular acoustic groove cavity.
2- The sub e t matter vct clai w re n sa r n n ssas s ar i the fa m of su s an ia l ra al sl t ext ndin th u h th upper portion thereof.
3. The subject matter of claim 1, wherein said ring comp ses a lo e erti n slidably fitt n the zbore of t e yl .,,d. r, a d a substa t al y .i'ad e l sl tte upper n r-tion 4. The subject matter of claim 1,-wherein said s ns-comp i e a l er no t onslidab fi i t bare or the c linder. and a s bst a l radia l s ed :up er por on. ou e ed e .o th
ad a [fins formed by .sa r i slot ng ,be n
set back to form an ular westibule ,between isaidannular .sound wave pa sage and the entran eenenings to the radial slots lead to th rmg groovecavity.
.5. The su ect mite -.Qf.c1 m ,,w ie eir sa se -ha k surface .of said piston is an uninterrupted surface of revolution about ,the longitudir al axis of .the piston. so to form said .sound wave .na ase as a c nn e e an u u ALBERT BODINE JR.
.No referen es c ted-