USOO6405704B2 (12) United States Patent (10) Patent No.: US 6,405,704 B2 Kruse (45) Date of Patent: *Jun. 18, 2002

(54) INTERNAL COMBUSTION ENGINE WITH 3,125,076 A 3/1964 Mullaney LIMITED TEMPERATURE CYCLE 3.266,234 A 8/1966 Cook 4,070,998 A 1/1978 Grow (75) Inventor: Douglas C. Kruse, Burbank, CA (US) 4.254,625 A 3/1981 Bergtedt et al. 4,503,833. A 3/1985 Yunick (73) Assignee: Kruse Technology Partnership, 4,704.999 A 11/1987 Hashikawa et al. Anaheim, CA (US) 4,798,184. A 1/1989 Palko 4,836,161 A 6/1989 Abthoff et al. (*) Notice: This patent issued on a continued pros- 4,854.279 A 8/1989 Seno ecution application filed under 37 CFR 4,858,579 A 8/1989 et al. 1.53(d), and is subject to the twenty year 4,862,859 A 9/1989 Yunick patent term provisions of 35 U.S.C. 4.913,113 A 4/1990 Baranescu 154(a)(2). 4977,875 A 12/1990 Kumagai et al. 5,101,785 A 4/1992 Ito Subject to any disclaimer, the term of this 5,265,562 A 11/1993 Kruse patent is extended or adjusted under 35 5,460,128 A 10/1995 Kruse U.S.C. 154(b) by 0 days. 5,566,650 A 10/1996 Kruse 6,058,904 A 5/2000 Kruse ...... 123/295 (21) Appl. No.: 09/567,870 FOREIGN PATENT DOCUMENTS (22) Filed: May 8, 2000 DE 2SO7142 9/1976 Related U.S. Application Data EP O482O55 7/1992 (63) Continuation of application No. 08/685,651, filed on Jul. 24, * cited by examiner 1996, now Pat. No. 6,058,904, which is a continuation of application No. 08/466,817, filed on Jun. 6, 1995, now Pat. No.08/146.833 5,566,650, filed which on Oct. is 29,a continuation 1993, now Patof applicationNo. 5,460,128. No. Primary Examiner- John Kwon which is a continuation of application No. 07/919,916, filed ASSistant Examiner Hieu T Vo on Jul 29, 1992, now Pat No. 5,265,562 (74) Attorney, Agent, or Firm-Fulwider Patton Lee & (60) Provisional application No. 60/001,617, filed on Jul. 28, Utecht, LLP 1995. s (51) Int. Cl...... F02B 1/14: FO2B 41/00 (57) ABSTRACT (52) U.S. Cl...... 123/295; 123/299 (58) Field of Search ...... 123/295, 299; An expandable ch amber type internal combustion 60/602;s 251/61.5 a combustionE. process E.having lity. a constant Volume (isochoric, st (56) References Cited phaseSC, followedOTOWC by a COnStant temperaturep (ISOthermaisothermal phase. U.S. PATENT DOCUMENTS 2.917,031 A 12/1959 Nestorovic 7 Claims, 9 Drawing Sheets

48 48

ECU E. so

14 26 28

32

3 O U.S. Patent Jun. 18, 2002 Sheet 1 of 9 US 6,405,704 B2

N N SN ES y

FIG | U.S. Patent Jun. 18, 2002 Sheet 2 of 9 US 6,405,704 B2

U.S. Patent US 6,405,704 B2

U.S. Patent Jun. 18, 2002 Sheet 5 of 9 US 6,405,704 B2

SIAIE (POINT 1)

P1 = INITIAL CYL PRESSURE AI BDC INTAKE STR, PSIA GIVEN If = INITIAL FLUID JEMP AI BDC GIVEN INTAKE STR, 'R GIVEN V1 = INITIAL CYL VOLUME AI BDC GIVEN INTAKE STR, IN CR = CYCLE COMPRESSION RAJIO GIVEN IMAX = MAXIMUM CYCLE TEMPERATURE, GIVEN R GIVEN N = ENGINE SPEED, RPM OFAR = OVERALL FUEL-IO-AIR RAIO

ISEWIROPIC COMPRESSION TO POINI 2

P2 - CY1, PRESSURE AI DC COMPR W2=VI/CR SIR PSIA KU-f I2 = FLUID TEMP AI IDC COMPR STR - Vf - 1 R 12–11 V2 + 1 W2 = CYL VOLUMEAT IDC COMPR STR NS IN-3 KU = RAJIO OF SPECIFIC HEAIS, KU UNBURNED MIXTURE P2=P1 K NS = ISENTROPIC EFFICIENCY W2 WV = CYCLE VOLUMETRIC EFFICIENCY WC=CWU(T1-12) WC = COMPRESSION WORK, BTU/lbm CWU = SPECIFIC HEAI, CONSTANT VOLUME, IMA=(NV)(N)(W1-W2)P1/21.3111 UNBURNED MIXTURE, BTU/lbm R IMA IOIAL MASS AIRFLOW. Ib/hr

POINT 2 FIG. 5A U.S. Patent Jun. 18, 2002 Sheet 6 of 9 US 6,405,704 B2

POINI 2 FIG. 5B LIMITED JEMPERATURE CONSIANT VOLUME COMBUSION IO POINI 3 PATH 2-3 P3 = CYL PRESSURE AN END OF CONSI WOL COMB, PSIA J3 as FLUID TEMPAT END OF CONST VOL COMB, 'R CY1, VOLUME AN END OF J3 = IMAX W3 CONST VOL COMB, IN 3 P3 = P2(13/12) CWB SPECIFIC HEAT, CONSTANT VOLUME, BURNED MIX, W3 = W2 (BTU/lbm "R) QCW = CVB(7.3–12) QCW = CONSIANT WOLUME COMB OMF = OFAR(IMA) HEAT, BTU/lbm OMF = OVERALL FUEL FLOW QIOT = OMF(QF) Ib/hr QCYC = NC(QTO)/(1+OFAR)(TMA) QIOI = IOTALBTU/hr FUEl HEAT INPUT, OF = LOWER HEATING VALUE OF FUEL, BTU/lbm NC = COMBUSION EFFICIENCY QCYC = CYCLE FUE HEAI INPUT,

CONSIANI IEMPERATURE COMBUSION/EXPANSION IO POINT 4 PAH 3-4 QC = CONSIAN TEMP COMB OCT=0CYC-(CW HEAT, BTU/lbm 14-73 P4 = CY1. PRESSURE AN END OF CONST TEMP COMB, PSIA CI J 14 FLUID JEMP Al END OF O CONST TEMP COMB, R wo RJ4 V4 CY1. WOLUME AT END OF CONST TEMP COMB, IN - CONVERSION CONSTANI, 778 ft-lbf/BIU WEXT-(9(?) in NT R = UNIVERSAL CAS CONSTANI, u P4 ft-lbf-- Ibn-R WEXT = EXPANSION WORK AJ CONSIANT IEMP, BTU/lbm NI = ISOIHERMAL EFFICIENCY

POINT 4 U.S. Patent Jun. 18, 2002 Sheet 7 of 9 US 6,405,704 B2

POINT 4 FIG. 5C ISEWJROPIC EXPANSION PATH 4-5

P5 CY1. AESSURE AT END OF ISENTROPIC EXP, PSIA I5 - FLUID JEMP AN END OF ISENTROPIC EXP R V5 - CY1. VOLUME AI END OF V5 - V1 ISENTROPIC EXP, IN J5 = 14(1-NS(1-4/.5) KB = RADIO OF SPECIFIC P5 = pa(/4/5) K5 HEAIS, BURNED MIXTURE WEXS = CVB(74-75) WEXS = EXPANSION WORK, ISENTROPIC, BTU/lbm CWB = SPECIFIC HEAI, CONSTANT VOLUME, BURNED MIX, BTU/lbm R

BLOWDOWN, EXHAUSI de INIAKE JO STATE 1 (ASSUMED IDEAL)

PERFORMANCE SUMMARY

WNET = NET INDICATED WORK, BIU/lbm WNET = WC+WEXT!-WEXS IHP = INDICAIED HP (PER IHP = (1+OFAR)(TMA)(WNEI)/2545 ) IMEP = INDICAIED MEAN IMEP = (792,000)(IHP)/(N)(Wi-V2) EFFECTIVE PRESSURE, NCYC = WNET/OJOI PSIA NCYC = INDICATED CYCLE EFFICIENCY U.S. Patent Jun. 18, 2002 Sheet 8 of 9 US 6,405,704 B2

FIG. 6

100%

90% PERCENT FUEl 80% SUPPLIED FOR CONSIANT 70% IEMPERATURE COMBUSION 60%

50%

402 MAX=3,300 R 30%

20% MAX=4,000 "R 10%

0% 8.1 10:f 121 141 16. 1 18.1 201 22.1 24:1 COMPRESSION RAIO

FIG. 7 IDC

HEAT RELEASE RATE BTU/ DEGREES

3.30 360 390 420 ANGLE, DEGREES U.S. Patent Jun. 18, 2002 Sheet 9 of 9 US 6,405,704 B2

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000Z 000|| 009 0009 000; 000£ 000Z 000||

N US 6,405,704 B2 1 2 INTERNAL COMBUSTION ENGINE WITH For general purpose road use, the engines of emission LIMITED TEMPERATURE CYCLE constrained passenger are presently limited to useful compression of about 10:1. Above that limit the increased REFERENCE TO RELATED APPLICATIONS cost of the fuel control system and the additional cost of 5 more platinum or rhodium for exhaust catalytic converters This application is a continuation of U.S. application Ser. generally outweighs the benefit of higher compression No. 08/685,651, filed Jul. 24, 1996, now U.S. Pat. No. ratios. A technology which would allow a practical Otto 6,058,904, which is a continuation to and claims the benefit compression process to operate at compression ratioS higher of U.S. application Ser. No. 08/466,817, filed Jun. 6, 1995, than 10:1 would be an advance in the art. now U.S. Pat. No. 5,566,650, which is a continuation of An improvement on the Otto cycle, as represented by a application Ser. No. 08/146,832, filed Oct. 29, 1993, now higher useful , is an ideal Diesel cycle U.S. Pat. No. 5,460,128, which in turn is a continuation of comprising isothermal heat addition and isochoric (constant U.S. application Ser. No. 07/919,916, filed Jul. 29, 1992, Volume) heat rejection combined with isentropic compres now U.S. Pat. No. 5,265,562. Sion and expansion. This ideal Diesel cycle overcomes the This application is also related to and claims the benefit of 15 fuel octane limit of the Otto cycle by utilizing air alone for U.S. Provisional Application No. 60/001,617, filed Jul. 28, the compression process and mixing the fuel with the 1995, through U.S. application Ser. No. 08/685,651, filed process air as part of the combustion process. This allows Jul. 24, 1996. use of a low octane-rated fuel, but requires cetane-rated fuel FIELD OF THE INVENTION (enhanced auto-ignition). However, the isothermal process of the aforedescribed ideal Diesel cycle was found to be The present invention relates generally to internal com impractical, due to the extremely high compression ratio bustion engines and more particularly to expandable cham (50:1) required, and an alternate heat addition process ber piston engines operating in an open thermodynamic (isobaric or constant pressure) was put into practice. cycle. Another variation on the ideal Diesel cycle is the ideal BACKGROUND OF THE INVENTION 25 limited pressure cycle including combined isochoric and isobaric heat addition, and isochoric heat rejection combined Automotive vehicle and engine manufacturers, fuel injec with isentropic compression and expansion. This combus tion equipment Suppliers and, indeed, Society as a whole, tion proceSS allows an engine to be operated at moderate share in the desire for efficient, effective transportation. The compression ratios (14:1 to 17:1 for large open chamber balance between combustion processes to produce power, engines) as well as high compression ratios (20:1 to 25:1 for and those processes which create pollution, is best addressed Small displacement engines). by enhancing the fundamental efficiency of the engine While Diesel-type engines are fuel efficient, due to their proceSSeS. high compression ratio, they tend to be heavier and lower in It is well known that the ideal Carnot Cycle, in which power than an Otto engine of the same displacement. In isothermal heat addition and rejection are combined with 35 addition, all direct injection engines of the Diesel type Suffer isentropic compression and expansion, is the most efficient from an ignition lag which reduces the control and effec engine cycle for any given upper and lower operating tiveness of the combustion process. One way to overcome temperatures. However, the Carnot cycle is not practical for this ignition lag is to preheat the fuel to 1,500 R before an expanding chamber piston engine due to the very high injection. This produces hypergolic combustion upon (over 50:1) compression ratio required to produce significant 40 injection, but is an impractical method due to the short power. Nevertheless, a practical process which could make Service life of the injector nozzle. Some use of the highly efficient Carnot proceSS would be an Hybrid engine processes have been developed incorpo advance in the art. rating characteristics of both diesel and Spark ignition The most practical engine, and thus presently the most engines but these have proven impractical for road use. predominant, is the Otto cycle engine which includes a 45 Examples of these hybrid processes include the Texaco compression process of a fuel-air mixture followed by TCCS, the Ford PROCO, Ricardo, MAN-FM and the KHD unregulated combustion. It is well known that for a given AD. All employ open chamber, direct injection Spark igni compression ratio the ideal Otto cycle is the most efficient tion engines using Stratified charge techniques to improve expanding chamber piston engine Since the Otto cycle efficiency. These developmental engines Suffer Substantial combines high peak temperature with a practical average 50 power loSS because of ignition lag, incomplete utilization of temperature of heat input. However, the high peak combus the proceSS air and poor mixing of the fuel/air charge. tion temperature of an Otto engine can cause auto-ignition of Because the limits of current technology are thus being a portion of the fuel-air mixture, resulting in engine noise reached, there exists a need for an internal combustion and damage to the engine, as well as the creation of exceSS engine that will provide a better balance between power amounts of undesired NOX. 55 production, fuel efficiency, pollution creation and pollution In the past, auto-ignition in Otto cycle engines was control by use of a more practical combination of thermo reduced by use of chemical additives to the fuel Such as lead dynamic processes. compounds (no longer permitted by law), manganese com pounds (which cause deposits to build up, result SUMMARY OF THE INVENTION ing in misfire), benzene (the use of which is presently being 60 Basically, the present invention meets the foregoing curtailed by legislative mandate) or fuel reformulations to requirements and constraints by utilizing a new combination prevent deleterious auto-ignition while meeting environ of thermodynamic processes which limits maximum com mental goals. Auto-ignition can also be reduced by limiting bustion temperatures, thereby enabling an internal combus the combustion temperature, either through use of a lower tion engine to operate at a higher compression ratio, a higher compression ratio (which reduces both power and 65 power output or a lower peak temperature with a given fuel. efficiency), or by exhaust gas recirculation, lean-burn or Broadly, in accordance with one exemplary embodiment, Stratified charge techniques, all of which cause power loSS. the invention is practiced by controlling the fuel quantity US 6,405,704 B2 3 4 and injection timing of a direct injection System in an tion enables the use of a higher engine compression ratio internal combustion engine, So as to produce a combustion with a commensurate gain in engine efficiency. process consisting of a constant Volume (isochoric) phase In Sum, the method of the present invention allows a and a constant temperature (isothermal) phase. The limited practical engine to make use of an ideal process: during the temperature engine cycle So achieved allows the use of Substantially higher compression ratios with a given fuel or isothermal combustion process, heat energy is converted with a given NOx emission limit, thereby providing a higher directly to work. The invention utilizes present engine practical thermal efficiency than the Standard lower com design and materials and may be practiced by modifying pression ratio Otto cycle when measured by fuel/air analysis existing internal combustion engines to incorporate the or by analyzing the test data of an actual engine. desired compression ratio and appropriate fuel introduction In addition, the limited temperature cycle So achieved Systems. allows a higher power output and a lower NOX creation rate at a given compression ratio with a low quality fuel. BRIEF DESCRIPTION OF THE DRAWINGS In accordance with another aspect of the invention, there Further objects, advantages and features of the invention is provided a new method of operating an expanding cham 15 will become evident from the detailed description of the ber internal combustion piston engine for providing limited preferred embodiment when read in conjunction with the temperature combustion. Such an engine includes at least accompanying drawings in which: one cylinder and an associated piston for forming a com FIG. 1 is a Schematic representation of a portion of a bustion chamber with the piston having a top dead center four-cycle internal combustion engine utilizing the prin position; an operating cycle including an intake , a ciples of the present invention; compression Stroke and an expansion Stroke, and a fuel FIG. 2 is a Side elevation view, in croSS Section, of a introduction System. The method of operating the engine Solenoid-operated fuel injector which may be used in the pursuant to the invention comprises the Steps of first forming engine depicted in FIG. 1, the injector including a plunger a predetermined fuel/air mixture by introducing a predeter providing volumes and rates in accor mined fraction in one or more discrete quantities of the total 25 dance with the present invention; fuel necessary for complete combustion of the process air. Next, the relatively lean fuel/air mixture so introduced is FIG. 3 includes plots of (1) fuel injector plunger lift ignited when the piston is Substantially at top dead center, versus engine crank angle and (2) injected fuel Volumes this first phase of combustion thereby comprising a Substan Versus engine crank angle in accordance with one exemplary tially isochoric or constant Volume process. The fuel Sup operating condition of an engine in accordance with the plied for the isochoric process is an amount which will present invention; produce a greatly reduced temperature of the working fluid, FIG. 4 shows pressure-volume and related engine cycle as low as 3,300 degrees Rankine, or less, even at high diagrams further explaining the cycle of the present inven compression ratioS. Last, there is introduced, Substantially at tion; the beginning of the expansion stroke, a second fraction (in 35 FIGS. 5A-5C together depict a flow chart showing steps one or more discrete quantities) of the total fuel necessary for analyzing the engine cycle of the present invention and for complete combustion. The combustion resulting from for calculating engine performance and other operating the introduction of the Second fraction is a Substantially parameters, isothermal process. The isothermal process occurs at a FIG. 6 includes plots of percent fuel supplied for constant temperature which is significantly less than that attained in 40 temperature combustion VS. compression ratio for two maxi a comparable Otto cycle engine having the same or a mum temperature (3,300 R and 4,000 R); Substantially lower compression ratio. NO emissions are FIG. 7 is a plot of heat release rate vs. crank shaft angle thereby limited and such reduction is obtained at lower cost for a process according to the invention having a maximum than existing Systems. temperature of 3,300 R; and Those skilled in the art will recognize that the method of 45 FIG. 8 shows pressure-volume and related engine cycle the present invention makes use of the Otto process for the first phase of the heat input or combustion proceSS and the diagrams relating to another embodiment of the invention. Carnot process for the Second phase of heat input or com DETAILED DESCRIPTION OF THE bustion proceSS. Comparison of the operating cycle of the PREFERRED EMBODIMENTS invention with the Standard Otto cycle using ideal fuel/air 50 analysis shows an unexpected benefit from the invention: the With reference to FIG. 1, there is shown in Schematic overall operating efficiency of an engine (with a given form a normally aspirated, four-cycle Spark ignition engine compression ratio) will be greater using the limited tem 10 employing the teachings of the present invention. It will perature cycle of the present invention than when using the become evident to those skilled in the art that the advantages Otto cycle, when high temperature losses are considered. 55 of the invention may be realized with two-cycle Spark This increase in efficiency at a given compression ratio is a ignition engines, as well as Wankel rotary-type engines and benefit derived from reduced cycle temperature. those that are turbo- or Supercharged. Further, although a Another advantage of the present invention is that it single cylinder is shown in FIG. 1 for simplicity, it will be allows an engine to be operated more efficiently (at a higher understood that an engine incorporating the invention will compression ratio) than is possible with present engines. The 60 typically have multiple cylinders. most readily available motor vehicle gasoline fuels have The engine 10 comprises a block 12, a 14 combustion quality ratings of about 90 octane, which gen and a cylinder 16 having a piston 18 adapted to reciprocate erally limits many engines to a compression ratio of about between top and bottom dead centers within the cylinder 16 10:1 for public road use. Since octane rating is indirectly to define with the cylinder 16 a 20. The related to high combustion temperature (high operating 65 of the piston 18 is converted to rota temperatures require high octane fuel), and the invention tional output motion by means of a 22 and a reduces the operating temperature, it follows that the inven crankshaft assembly 24, all as well known in the art. As will US 6,405,704 B2 S 6 be explained in greater detail below, in accordance with the already explained, the fuel Volumes A and B are functions invention the compression ratio of the engine 10 will typi only of the durations that the injector 38 is active, as cally be Substantially higher than that of a conventional determined by the electronic control unit 48. automotive Spark ignition internal combustion engine. For Usually, a fuel injection pump is driven at Speed, example, while a conventional engine may have a compres that is, at one half engine crankshaft Speed. Here, the pump Sion ratio of 8:1 to 10:1, an engine employing the teachings is rotated at engine crankshaft Speed with the embodiment of the present invention may have a compression ratio of shown in FIG. 2 having its cam lobe 58 starting its lift 18:1. essentially at the beginning of the engine intake stroke (O). The engine 10 further includes an air induction system 26 This provides a first fuel injection volume (shown as A in including an air intake 28 in the cylinder head 14. The FIG. 3) during the intake stroke, similar to an Otto engine. valve 28, along with an exhaust valve (not visible in FIG. 1), The pump cam 56 completes its first rotation at the end of is actuated by a conventional camshaft 30 and related valve the engine compression stroke (360'). The next rotation of train mechanism 32. Also mounted in the cylinder head 14 the pump cam 56 will inject the second fuel volume (volume is a Spark plug 34 whose energization is controlled and timed B) during the power Stroke in a manner which produces by means well known in the art. 15 essentially constant temperature combustion. Referring now also to FIG. 2, fuel is supplied to the Fuel volume A, comprising about 56% of the total fuel engine 10 by a fuel injection system 36 which precisely required for complete combustion of the process air, is regulates the fuel/air mixture for combustion and exhaust injected during the intake stroke of the piston 18 between emission control. The fuel injection System 36 includes an about 10 and 120° (engine crank angle) after top dead electrically actuated fuel injection pump 38 installed in or center. Substantially at the end of the compression Stroke adjacent to the cylinder head 14 and adapted to inject (360 or top dead center), the Second Volume, B, comprising predetermined quantities of fuel directly into the combustion the remaining 44% of the total amount of fuel required for chamber 20 via an injection line 40 and an injector nozzle 41 complete combustion, is injected, Such Second injection terminating inside the combustion chamber 20 and adjacent terminating at about 60 after TDC, i.e., at about 420. to the Spark plug. 34. The injector pump 38 may, for example, 25 Ignition by the Spark plug 34 in the example under consid take the form of a Model 200 fuel injection unit manufac eration will typically be provided at 5 to 10 before top tured by AMBAC International, with a modified cam as dead center. described below and the addition of a Solenoid 44. The The combustion of the fuel/air mixture based on injected injector pump 38 has a fuel Spill valve 42 operated against Volume A comprises a first combustion phase which, as in the bias of a spring 43 by the Solenoid 44 energizable by a the Standard Otto cycle, is a Substantially constant Volume solenoid drive unit (SDU) 46. The drive unit 46 is in turn process. The first combustion phase will, of course, com controlled by an electronic control unit (ECU) 48 which prise a very lean mixture which, in the absence of the Second monitors, by means of appropriate Sensors, Selected engine phase of combustion to be described, would tend to mark operating conditions Such as intake and edly reduce engine power. The combustion of fuel volume B preSSures, engine Speed, ignition firing position, 35 takes place at Substantially constant temperature, that is, position, engine temperature, and So forth. Electrical Signals isothermally, providing both power and efficiency. It has representing these conditions are applied as inputs 50 to the been determined that the temperature at which this Second control unit 48. AS is known in the art, the electronic control combustion phase takes place is limited and less than that unit 48, based on the multiple inputs 50, electronically which would be attained in a Standard Otto cycle engine of calculates the timing and metering of the fuel introduced 40 even modest compression ratio, for example, 8:1 or 10:1. into the combustion chamber 20 by the injection pump 38. Thus, the limited temperature cycle of the present invention Fuel is supplied to the fuel injector unit 38 by a feed pump permits the designer to dramatically increase the compres (not shown) through a fuel line 52 at a sufficiently high Sion ratio of an engine for a given fuel, for example, to as preSSure to produce proper fuel flow and to prevent vapor high as about 18:1, providing all of the advantages, includ formation in the fuel System during extended high 45 ing high efficiency and power output, derived from a high temperature operation. When the Solenoid 44 is energized by compression ratio engine without the thermal, detonation the Solenoid drive unit 46, the valve 42 closes and, because and emission penalties. the displacement of the plunger 54 is known, the fuel A majority of the fuel is pre-mixed, generally 50% to quantity injected is controlled Solely by varying the injector 50 90%, for constant volume combustion. This first process is pulse width, that is, the duration the valve 42 is held closed. combined with a Second fuel portion Supplied during the The injector pump 38 includes a piston type pumping combustion process at a rate to, first, limit maximum plunger 54 actuated by a cam 56 having a cam follower preSSure, and Second, limit maximum cylinder temperature. surface or cam lobe 58 in engagement with the plunger 54; The engine cycle of the present invention has a higher the cam 56 is rotatable at engine crank shaft Speed. 55 thermal efficiency than a Carnot cycle with the same average As shown in FIG. 3, the cam 56 has a lift profile, as a temperature of heat input. function of crank angle, having a first linear portion 60 rising FIG. 4 shows three engine cycle diagrams (pressure from a base circle 62 to a maximum lift of about /2 inch Volume, temperature-volume, and temperature-entropy) through an angular crank displacement of about 180, and a comparing examples of the limited temperature cycle of the Second linear portion 64 dropping back to the base circle in 60 present invention for two maximum combustion chamber about 60 of crank displacement. temperatures (T,), namely, 3,300 R and 4,300 R. The FIG. 3 shows a fuel injection schedule for a single, engine cycle of the first example (T=3,300 R) is defined exemplary operating condition, namely, wide open throttle by the points 1-2-3-4-5-1 in the diagrams of FIG. 4 and that for a Limited Temperature Cycle, four-cycle engine having of the second example (T=4,300 R) by the points a compression ratio of 18:1 and a peak temperature of about 65 1-2-3'-4'-5'-1. In FIG. 4, path 1-2 is an 18:1 isentropic 3,300 R. The fuel injection schedule of FIG. 3 provides for compression and paths 2-3 and 2-3' are constant Volume two Successive injections of fuel Volumes A and B. AS combustion processes using, in the first example, 56% of the US 6,405,704 B2 7 8 fuel necessary for complete combustion of the process air. -continued Paths 3-4 and 3'-4" are isothermal processes using, in the first T4 = T3 = 3300R example, the remaining 44% of the fuel. Paths 4-5 and 4'-5' are isentropic expansion processes and paths 5-1 and 5'-1 are V4 = (V3)eteria) = (2.79)e (319) (778) = 11.41 in constant Volume exhaust processes. (53.4) (3300) Using the ideal fuel/air analysis of FIGS. 5A-5C, the P4 = P:( ) 159: 2.79 = 389 psi conditions or rates at each point for the two examples of = r(t) = 139 – 389 psia FIG. 4 may be calculated as follows: WCTE = (R) (T4) ( FIRST EXAMPLE p T = (53.4 is(3300) (1593389 (95. = 303 Btuf Ibn

CR=18.0 Tfix =3300 R Point 1-Initial Conditions at BDC, Intake Stroke: where: Point 5-Following Isentropic Expansion (Path 4-5): 15 Ke = 1.26 P1 = initial pressure V1 = initial volume Ce = .325 T1 = initial temperature N = engine speed Cyer = .25 N. = compression/expansion efficiency F/A = fuel/air ratio Vs = V = 50.3 in M. = air mass flow LHV = fuel lower heating value N = volumetric efficiency V4 K-1 11.41126-1 NCOMB = combustion efficiency 25 14| N.( () aso. s: lit. = 22979R Point 2-Following Isentropic Compression (Path 1-2): P5 = P4 V4V5 ) Kax =389(5) sis = 60 psia K = 1.37 WEx = C, (T4 - T5) = .25 (3300-2297) = 251 Btuf Ibn C = .186 Btuf Ibm-R 50.3 :-3 Performance Summary of Cycle of First Example: V2 = Vlf CR = --18 = 2.79 in W1 K-1 ()2 - 1 + 1 W = WC+ WEXT + WEX = -198+303+251 = 356 Btuf Ibn Ns 35 IHP (1 + F/A)2545 (Ma)(W) (1.0416)2545 (130)(356) = 18.94 HP P2 = P(E)W1YK = 14.7(18)'''37 = 771 psia (792,000) (IHP) (792000) (18.94) MEP = -(N) (V1 -V2 - =- -2000) - (S03 - -- 270 - =- 15818 psidpsi WC = C(TI - T2) = . 136(530-1597) = - 198 Btuf Ibn 40 N.cyc =- Oe =-73 , =48.7%- to: O Point 3-Following Limited Temp. Comb. G.) Constant Volume (Path 2-3): SECOND EXAMPLE T = Tmax = 3300° R 45 Point 1-Initial Conditions at BDC, Intake Stroke: 3300 Same as first example. P3 = P2(T3 (T2) = (771. = 1593 psia Point 2-Following Isentropic Compression (Path 1-2): 1597 Same as first example. Point 3'-Following Limited Temp. Comb. G.) Constant V3 = V2 = 2.79 in 50 Volume (Path 2-3): Q = C(T3 - T2) = .242(3300-1597) = 412 Btuf Ibn T = Tmax = 4300°R M = F / A(Ma) = (.0416). (130) = 5.408 lb/hr. 4300 1597 Q = (Mr.) (LHV) = (5.408) (18,300) = 98.966 Bu?hr 55 (N.)(QTOT) (1.0) (98.966) 2cle (1 + OFAR) (TMA) (1.0416) (130) Qey f Qcycle = 412/731 = 56.4% - % of comb at C.V. 60 Q = (Mr.) (LHV) = (5.408) (18,300) = 98.966 Bu?hr Point 4-Following Constant Temperature Combustion and (N.) (QTOT) (1.0) (98.966) Expansion (Path 3-4): Qost (1 + OFAR) (TMA) (1.0416) (130) 65 Q = QCyCLE - Q = 731 - 412 = 319 Btuf Ibn - (43.6% at C.T.) Q f Qc = 654f731 = 89.5%. - % of comb at c. v. US 6,405,704 B2 10 Point 4-Following Constant Temperature Combustion and (volume A) to take place at the beginning of the compression Expansion (Path 3'-4"): Stroke and the Second injection (Volume B) to take place as in the four cycle engine. In the two cycle application, the Q = QCyCE - Q = 731 - 654 = 77 Btu flbin - (10.5% at C.T.) active portion of the cam lobe must extend from the begin ning of the compression Stroke to the end of the isothermal T4 - T3 - 4300R combustion process. Since this is an extended duration with -- (77) (778) a significant non-utilized portion of the lift ramp, a constant V4 = (V3')e(0.(V3)e Rf7) = (2.79)e-'l'-(2.79 essario, =3.62 in radius portion on the cam can be used to avoid excessively high total cam lobe dimensions. P4 = P3?)=207d P= 1600 psi Instead of a fuel injection pump (as shown in FIG. 2) = P() = 2076)=1600 psia those skilled in the art will understand that a Solenoid WCTE = controlled unit injector can be used or, as a further alternative, a fuel injection System, fed by a thyr in (NVT = isElli? E.95)(). ) = 72972.9 Bu?ibBtuf Ibn constant-flow, high-pressure pump, can be utilized with the 15 injectors independently controlled by Solenoids. Still further, Point 5-Following Isentropic Expansion (Path 4'-5'): it will be obvious to those skilled in the art that piezoelectric actuators may be substituted for the Solenoids where very Short injector energization times (that is, Small fuel Ke = 1.26 quantities) are required. Piezoelectric actuators may also be Cpe = .325 utilized to provide a higher degree of control over injection Since Such injectors may be used to inject multiple discrete Cyer = .25 quantities with the result that the process will more closely V: = V = 50.3 in follow the ideal isothermal process paths. In accordance T5 - with yet another alternative, a piezoelectric device may be 25 Substituted for the pump plunger in a unit injector, thus 3,621.26-1 2.2750R eliminating the requirement for a cam to actuate the injector. 50.3 To make Such an application of a piezoelectric actuator Tri-N(-(-)-430-9:- practical, the piezoelectric device would be actuated mul , ( V4'Yes 3.62 Yl.26 P5 - P4 160 (3) = 58 psia tiple times (for example, 100 times) by the electronic control V5 unit in order to inject the required total fuel quantities with Wy = C(T4 - T5') = .25(4300-2275) = 506 Btuf Ibn a practical Size piezoelectric element. It will also be appreciated that the process diagrams of FIG. 4 show ideal processes. Real engine paths will depart Performance Summary of Cycle of Second Example: to Some extent from the ideal cycles shown due to timing, 35 heat and friction losses. These factors will manifest them W = WC+ WEXT + WEX = -198+72.9+5.06 = 381 Btuf Ibm. Selves in the cycle diagram as, for example, rounded corners (1 + F/A) (Ma)(W) (1.0416) (130)(3.81) and displacements of the process lines. IHP 2545 2545 = 20.27 HP To practice the present invention, it is also possible to combine a Standard fuel introduction System with (792,000) (IHP) (792000) (20.27) 169 psi 40 an injector. With reference to the example of FIG. 3, with (N) (V1 V2 - 2000) (SO3-270 - 109 Psld Such a System, the carburetor would Supply the first quantity N. = e = t = 52% (volume A) and the injector would Supply the Second oc = 0 = 73 - 47 quantity (volume B). The use of an injector for introducing both fuel charges is preferred, however, to minimize cost. In another embodiment of the invention, the fuel supplied 45 The invention can also be put into practice in combination for the isochoric event may be an amount which will with existing Otto, Diesel, lean-burn or Stratified charge produce a temperature of the working fluid of around 4,000 engine processes in the same engine at different loads or degrees Rankine, Somewhat leSS than that produced by different operating conditions. unconstrained combustion, with the remainder of the fuel In Some applications there will be a value to limiting Supplied proportional to the increase in Volume during the 50 maximum cylinder pressure. In that instance, the invention power Stroke, to produce essentially isothermal combustion. can make use of a further embodiment: a combination of This embodiment will produce high power, while avoiding constant Volume combustion, constant pressure combustion, detonation at higher compression ratioS. and constant temperature combustion. In this embodiment of FIG. 6 shows plots for two maximum combustion tem the invention, heat is released during the constant Volume peratures (3,300 R and 4,000 R), of percent fuel supplied 55 process in Such an amount as to reach the preferred preSSure for constant temperature combustion as a function of com limit. Heat is then added at constant preSSure until the pression ratioS ranging from 8:1 to 24:1. preferred maximum temperature is reached. The remaining FIG. 7 is a plot of heat release rate as a function of engine heat is added isothermally. An example of Such an embodi crankshaft angle for a maximum combustion temperature of ment is shown in the process diagrams of FIG. 8. An engine 3,300 R (First Example, above). A first portion 70 of this 60 operated in accordance with this embodiment will include, plot shows the heat release rate for the constant Volume with reference to FIG. 8, the following process paths: path process (path 2-3 in FIG. 4). A second portion 72 of the plot 1-2 is an isothermal compression proceSS during which fuel shows the heat release rate for the isothermal process (path is Supplied. The fuel Supplied early in the compression 3-4 in FIG. 4). process Serves two purposes: first, the heat of vaporization With reference again to FIG. 3, it will be evident to those 65 reduces the work of compression, Second the combustion skilled in the art that the invention may be applied to two temperature is reduced proportional to the cooling provided cycle engines simply by Scheduling the first injection by the fuel, and third, the early injection allows time for US 6,405,704 B2 11 12 preflame reactions to take place prior to the ignition time, ratio, even higher than previously indicated herein, e.g., as thus reducing ignition lag (a significant problem for Diesel high as about 24:1 is practical. A similar piezoelectric or other predominantly direct injection hybrid Systems). actuator could be substituted for the Solenoid 44 of FIG. 1. Path 2-3 is an isentropic compression process, as already Piezoelectric materials developed by or in association with explained; path 3-4 is an isochoric combustion process with NASA Langeley Research Center, and known as the “Rain maximum pressure limited to a preselected value by pro bow” and “Thunder' piezoelectric materials have design portioning fuel quantity A (FIG. 3); path 4-5 is a constant concerns related to those also of concern here. preSSure, i.e., isobaric, proceSS provided by a first portion of By combining a higher compression ratio, as high as 24:1, with a lean burn and multiple injection, the limited tempera fuel fraction B (FIG. 3), said portion being of an amount so ture cycle can produce higher power combined with higher as to continue isobaric combustion until the preselected thermal efficiency while avoiding detonation (auto-ignition), maximum combustion temperature is reached; path 5-6 is an at a compression ratio above the highest conventionally isothermal combustion process at the preselected maximum useful value. combustion temperature; path 6-7 is an isentropic expansion A number of the matters herein are also discussed in a process, and path 7-1 is an isochoric exhaust process. Each paper, D. C. Kruse and R. A. Yano, SAE (Society of of the fuel introductions can comprise one or more discrete 15 Automotive Engineers), Technical Paper No. 951963 quantities So as to follow the ideal processes as closely as (1995), which is incorporated herein by reference. practicable. It will also be understood that the invention can be used With reference once again to FIG. 3, an additional with various fuels. Such as natural gas, diesel, gasoline and embodiment of the invention can be put into practice by methanol, as well as with multiple fuels including, for subdividing the first fraction (volume A) of the total fuel example, a combination of natural gas for the constant quantity into one or more discrete injected fuel portions. For Volume heat release proceSS and diesel fuel for the isother example, if two Such portions were used, these would be mal heat release process. designated portions A and A", the Sum of these two portions What is claimed is: equalling the Volume A. In accordance with one example of 1. A method of operating an internal combustion expand this embodiment, the first fuel portion A', comprising 40% 25 of the total fuel, would be injected during the interval from ing chamber piston engine for providing limited temperature 10 to 80 of engine crank shaft rotation and the second fuel combustion, said engine having (1) at least one cylinder and portion A", comprising 16% of the total fuel, would be an associated piston for forming a combustion chamber, Said injected during the interval from 320 to 350 of engine piston having a top dead center position, (2) an operating crank rotation. This embodiment provides a chemically cycle including an intake Stroke, a compression Stroke and correct fuel/air mixture Surrounding the Spark plug for the an expansion Stroke, and (3) a fuel introduction System, said first phase of combustion Serving to extend the lean misfire method comprising the Steps of limit as well as further reducing the creation of No by forming a fuel/air mixture by introducing a fraction of the avoiding the presence of unburned oxygen in the first total fuel for the cycle; combustion phase. 35 igniting the fuel/air mixture when the piston is Substan With reference once again to FIG. 1, this arrangement can tially at top dead center; and readily be used to produce a lean overall fuel/air mixture in introducing at least one additional fraction of the total fuel the entire combustion chamber 20, along with an ignitable for the cycle during combustion in a predetermined fuel/air mixture in that portion of the combustion chamber phase relationship to the top dead center position; adjacent to the Spark plug. 34. This Spatial Stratification will 40 wherein the timing of the introduction of the fuel fractions be in combination with temporal Stratification with injection and the quantities of the fuel fractions limit the maxi timing for the fuel portion A" provided by Solenoid 44 mum combustion temperature to achieve a lower emis actuation just prior to the time that the Spark plug provides Sion value for nitrogen oxides. an ignition Spark. When this arrangement is combined with 2. A method as defined in claim 1, wherein the maximum inlet pressure, designated as point 1 on FIG. 4(A), elevated 45 combustion temperature is Substantially defined by an iso from a naturally aspirated value of about 14.7 pounds per thermal line on a pressure-volume diagram for a cylinder Square inch absolute to a new value as high as about 40 and cycle. pounds per Square inch absolute (i.e., compressed air 3. A method as defined in claim 3, wherein the timing and through Super-or turbo-charging), the power density of an quantities of the fuel fractions introduced into the combus engine with a compression ratio of 14:1 and a lean overall 50 tion chamber produce a combustion temperature that is leSS fuel/air ratio of 40% of stoichiometric can equal or exceed than or equal to the temperature for the isothermal line. the power density of an equivalent homogeneous charge 4. A method as defined in claim 1, wherein the fuel naturally aspirated engine. In an arrangement Such as this, expansion Stroke includes a Substantially isentropic power inlet preSSure at least as high as about 20 pounds per Square delivery process. inch absolute, typically, would be expected. 55 5. A method of operating a Spark ignition internal com Along lines previously adverted to, an alternative arrange bustion expanding chamber piston engine for providing ment to that of FIG. 1 can be put into practice by use of a limited temperature combustion, said engine having (1) at high pressure pump to feed the fuel line 52, eliminating the least one cylinder and an associated piston for forming a use of the individual plunger injection of pump 38 of FIG. combustion chamber, Said piston having a top dead center 1. Such an arrangement can be put into practice by use of a 60 position, (2) an operating cycle including an intake Stroke, a Substitute injector pump, including a pumping plunger Simi compression stroke and an expansion Stroke, and (3) a fuel lar to the plunger 54 of FIG. 2, but actuated by a piezoelec introduction System, Said method comprising the Steps of: tric device to engage the plunger rather than a cam Such as forming a predetermined fuel/air mixture by introducing the cam 56. Then the piezoelectric actuator can be operated air compressed to at least 20 pounds per Square inch multiple times (for example in the range of 100 times), 65 and fuel for combustion of the air into the combustion providing multiple injections for a given combustion activ chamber, the fuel/air mixture being Substantially leSS ity or event. With Such a piezoelectric device, a compression than Stoichiometric, US 6,405,704 B2 13 14 compressing the fuel/air mixture to a State leSS than the 7. A method of operating an internal combustion engine, autoignition State of the fuel/air mixture with a com Said engine having an operating cycle including an intake pression ratio of at least 14:1; process, a compression process followed by an expansion igniting the fuel/air mixture when the piston is Substan process which includes a heat input phase, the method tially at top dead center; including the Step of introducing fuel into the combustion wherein the combustion of the fuel/air mixture is Sub chamber during Said intake process, the vaporization of the Stantially a limited temperature process proceeding fuel So introduced Substantially reducing the work of com without autoignition. pression. 6. A method as defined in claim 5, wherein the fuel/air mixture is about 40% of Stoichiometric. UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION

PATENT NO. : 6.405,704 B2 Page 1 of 1 DATED : June 18, 2002 INVENTOR(S) : Douglas C. Kruse

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below: Title page, Item, add the following Statement: -- This patent is subject to a terminal disclaimer --. Item 63, Related U.S. Application Data, after “Pat. No. 6,058,904,” delete “is a continuation of, and replace with -- which claims benefit of --. Column 1 Line 7, delete “which is a continuation to” and replace with -- which is related to --. Column 2 Line 63, change "temperatures” to read -- temperature --.

Column 7 Line 13, delete “where:” and add the following: -- P1 = 14.7 psia V1 = 50.3 in T1 = 530R N = .95 F/A = .0416 M = 130 lb/hr LHV = 18,300 Btu/Ib N = 100% NCOMB = 100% where: --. Line 39, change “136', to read -- 186 --.

Signed and Sealed this Twenty-fifth Day of March, 2003

JAMES E ROGAN Director of the United States Patent and Trademark Office UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION

PATENT NO. : 6.405,704 B2 Page 1 of 1 DATED : June 18, 2002 INVENTOR(S) : Douglas C. Kruse

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Column 12 Line 48, change “3’ to read -- 2 --.

Signed and Sealed this Fifteenth Day of July, 2003

JAMES E ROGAN Director of the United States Patent and Trademark Office Disclaimer 6,405,704, B2 Douglas C. Kruse, Burbank, CA (US). INTERNAL COMBUSTION ENGINE WITH Li MITED TEMPERATURECYCLE. Patent dated June 18, 2002. Disclaimer filed November 14, 2011, by the assignee. Kruse Technology Partnership. Hereby enters this disclaimer to claims 1-7 of said patent. (Official Galette, March 20, 2012) USOO6405704C1 (12) EX PARTE REEXAMINATION CERTIFICATE (8999th) United States Patent (10) Number: US 6.405,704 C1 Kruse (45) Certificate Issued: May 8, 2012

(54) INTERNAL COMBUSTION ENGINE WITH (51) Int. Cl. LIMITED TEMPERATURECYCLE F02B 75/02 (2006.01) FO2B 4I/00 (2006.01) (75) Inventor: Douglas C. Kruse, Burbank, CA (US) (52) U.S. Cl...... 123/295:123/299 (73) Assignee: Kruse Technology Partnership, (58) Field of Classification Search ...... None Chatsworth, CA (US) See application file for complete search history. Reexamination Request: No. 90/011,631, Apr. 7, 2011 (56) References Cited Reexamination Certificate for: To view the complete listing of prior art documents cited Patent No.: 6.405,704 during the proceeding for Reexamination Control Number Issued: Jun. 18, 2002 90/011,631, please refer to the USPTO's public Patent Appl. No.: 09/567,870 Application Information Retrieval (PAIR) system under the Filed: May 8, 2000 Display References tab. Disclaimer of claims 1 through 7 filed Mar. 20, 2012 (1376 Primary Examiner David O. Reip OG. 393) (57) ABSTRACT Certificate of Correction issued Mar. 25, 2003. An expandable chamber piston type internal combustion engine operating in an open thermodynamic cycle includes a Certificate of Correction issued Jul. 15, 2003. combustion process having a constant Volume (isochoric) phase followed by a constant temperature (isothermal) Related U.S. Application Data phase. (63) Continuation of application No. 08/685,651, filed on Jul. 24. 1996, now Pat. No. 6,058,904, which is a continuation of application No. 08/466,817, filed on Jun. 6, 1995, now Pat. At the time of issuance and publication of this certificate, No. 5,566,650, which is a continuation of application No. the patent remains subject to pending reexamination 08/146,832, filed on Oct. 29, 1993, now Pat. No. 5,460,128, which is a continuation of application No. 07/919,916, filed control number 95/001,730 filed Oct. 21, 2011. The claim on Jul. 29, 1992, now Pat. No. 5,265,562. content of the patent may be subsequently revised if a (60) Provisional application No. 60/001,617, filed on Jul. 28, reexamination certificate issues from the reexamination 1995. proceeding.

US 6,405,704 C1 1. 2 EX PARTE AS A RESULT OF REEXAMINATION, IT HAS BEEN REEXAMINATION CERTIFICATE DETERMINED THAT: ISSUED UNDER 35 U.S.C. 307 Claims 1-7 are now disclaimed. (Statutory disclaimer in 5 present reexamination). THE PATENT IS HEREBY AMENDED AS INDICATED BELOW. k . . . .