CN105888837A - Double-crankshaft homogeneous compression-ignition engine - Google Patents

Abstract

The invention provides a double-crankshaft homogeneous compression-ignition engine. The engine is characterized by consisting of a main crankshaft and an auxiliary crankshaft, wherein the main crankshaft is connected with a main connecting rod, and a main piston reciprocally moves in a main cylinder; the auxiliary crankshaft is connected with an auxiliary connecting rod, and an auxiliary piston reciprocally moves in an auxiliary cylinder; the main and auxiliary crankshafts are arranged below the cylinders in parallel, and are connected through a pair of gears at the gear ratio of 1:2; four strokes of suction, compression, work application and exhaust are implemented every time when the main cylinder rotates 720 degrees, and meanwhile, two strokes of compression and suction are implemented every time when the auxiliary cylinder rotates 360 degrees; oil is only injected into the main cylinder by an oil injection nozzle, compressed air is provided for the main cylinder by the auxiliary cylinder, the auxiliary crankshaft falls behind the main crankshaft by a phase angle, and the maximum compression ratio position is below the upper dead center of the main piston, so that the detonation rate is low, and the best solution for the homogeneous compression-ignition engine is provided.

Description

A kind of double-crankshaft homogeneity compression-ignition engine

Technical field

The present invention is a kind of double-crankshaft homogeneity compression-ignition engine, it is characterized in that electromotor is made up of main crankshaft and secondary crankshaft, main crankshaft Connecting master connecting-rod, main piston to move back and forth in master cylinders, secondary crankshaft auxiliary connection connecting rod, auxiliary piston move back and forth in auxiliary steam cylinder, Major and minor bent axle is arranged in parallel in cylinder and connects below by a pair gear, and the gear ratio of gear is 1: 2, and main crankshaft often rotates 720 Spent air-breathing, compress, do work, four strokes of aerofluxus, secondary crankshaft rotates 360 degree and completes compression and two strokes of air-breathing simultaneously, Atomizer is only toward oil spout in master cylinders, and auxiliary steam cylinder provides compressed air for master cylinders, the volume of auxiliary steam cylinder be more than master cylinders twice with On, secondary crankshaft falls behind one phase angle of main crankshaft, and at compression stroke latter end, major and minor piston compresses the mixing in master cylinders jointly Gas makes up to maximum pressure and ignition does work, certain position under main piston top dead centre, the position of maximum compression ratio, all Abnormal combustion, all without producing pinking, is the best solution of homogeneity compression-ignition engine.

Background technology

Homogeneity compression-ignition engine is called for short hcci engine it is considered to be a major progress of engine combustion technology, with tradition Gasoline engine or diesel engine compare, hcci engine use homogeneous charge compression-ignition, this electromotor have the high thermal efficiency, The advantage of extremely low NOx and PM, has the advantage of energy-conserving and environment-protective, but, common hcci engine burns all each time It is the edge in pinking, it is necessary to accurately controlling in the point of origin moment, pinking easily to occur, rough running is unstable, ordinary construction Electromotor can only use HCCI mode to work in the narrowest scope, and there is load pinking low, easy, control the problems such as difficult, So how solve hcci engine pinking and become a core difficult problem.

Goal of the invention and advantage

The double-crankshaft homogeneity compression-ignition engine of the present invention, the problem solving hcci engine pinking the most exactly, it is characterized in that sending out Motivation is made up of main crankshaft and secondary crankshaft, and main crankshaft connects master connecting-rod, main piston and moves in master cylinders, and secondary crankshaft auxiliary connection is even Bar, auxiliary piston move in auxiliary steam cylinder, and major and minor bent axle is connected by a pair gear, and the gear ratio of gear is 1: 2, master cylinders Do air-breathing, compress, do work, while four strokes of aerofluxus, auxiliary steam cylinder does compression and two strokes of air-breathing, and atomizer is only toward main Vapour cylinder-in oil-jet, auxiliary steam cylinder provides compressed air for master cylinders, certain under main piston top dead centre of the position of maximum compression ratio Position, fuel oil is work by combustion in master cylinders, even if there being uncontrolled burning i.e. detonation, due to point of origin piston top dead center it Under, now piston runs downwards, and pinking would not occur, so double-crankshaft hcci engine working range is the widest and quick-fried There is very little risk in shake, it is not necessary to accurately controlling the point of origin moment, control system cost is the lowest, have splendid fuel economy and Environment-friendly advantage, is the best solution of hcci engine.

Summary of the invention

Double-crankshaft homogeneity compression-ignition engine (see Fig. 1), it is simply that the problem of hcci engine pinking to be solved, is characterized in that electromotor Be made up of main crankshaft (1) and secondary crankshaft (2), have in cylinder body (9) master cylinders and auxiliary steam cylinder, major and minor bent axle be arranged in major and minor cylinder it Under, main crankshaft (1) connects master connecting-rod (5), main piston (7) moves back and forth in master cylinders, secondary crankshaft (2) auxiliary connection connecting rod (6), pair Piston (8) moves back and forth in auxiliary steam cylinder, and major and minor bent axle is connected by gear Z1 (3), gear Z2 (4), and gear Z1 (3) assembles On main crankshaft (1), the number of teeth is z1, and gear Z2 (4) is assemblied on secondary crankshaft (2), and the number of teeth is z2, gear Z1 (3) and gear Z2 (4) Engagement, z1: z2=1: 2, the rotation direction phase reversal speed ratio of the most major and minor bent axle is 2: 1, and main crankshaft (1) rotates 720 degree Complete air-breathing, compress, do work, while four strokes of aerofluxus, secondary crankshaft (2) rotates 360 degree and completes compression and air-breathing two punching Journey, cylinder cap (10) is positioned on major and minor cylinder, and there are main air intake (16), secondary air intake duct (17), exhaust duct (18) in inside, lead, Communicated by secondary air intake duct (17) between auxiliary steam cylinder, and controlled the folding of secondary air intake duct (17), inlet valve I (13) by inlet valve II (12) Being assemblied on main air intake (16), inlet valve II (12) is assemblied on secondary air intake duct (17), and exhaust valve (11) is assemblied on exhaust duct (18), Atomizer (14) is only toward oil spout in master cylinders, and auxiliary steam cylinder provides compressed air for master cylinders, and master cylinders, when acting and aerofluxus, enters Valve I (13) opens, and inlet valve II (12) closes, and air is inhaled into auxiliary steam cylinder from main air intake (16), and master cylinders is in air-breathing and compression Time, inlet valve II (12) opens, and inlet valve I (13) closes, and the air in auxiliary steam cylinder is compressed and passes through secondary air intake duct (17) to be entered main Cylinder, backward one the phase angle X of main crankshaft of secondary crankshaft, and the volume of auxiliary steam cylinder are that the twice of master cylinders volume is many, master cylinders A diameter of D1, length of stroke is L1, a diameter of D2 of auxiliary steam cylinder, and length of stroke is L2, D1²·L1∶D2²L2 ＜ 1: 2, The position of maximum compression ratio is under main piston (7) top dead centre, and phase angle X is the biggest, and maximum compression ratio position the most on the lower, is started The burning bandwidth of machine is the widest, and the thermal efficiency is the lowest, and fuel oil can any one between top dead centre and maximum compression ratio position Work by combustion, at close near top dead center advanced combustion during gaseous mixture overrich, when gaseous mixture is crossed dilute, at maximum compression ratio Burning, owing to being main piston ignition during running downwards, so electromotor there's almost no the problem of pinking, is HCCI The solution that electromotor is best.

The second structure that major and minor bent axle connects is for by gear Z1, gear Z3 and gear Z2 connection (see Fig. 3), gear Z1 The number of teeth be z1, the number of teeth of gear Z3 is z3, and the number of teeth of gear Z2 is z2, z1: z2=1: 2..

The second structure of double-crankshaft homogeneity compression-ignition engine be the phase angle between double-crankshaft be variable (see Fig. 8, Fig. 9), its Feature be the phase angle that can adjust major and minor bent axle to change the compression ratio of electromotor, engine body structure is identical, difference Place is that gear Z2 (4) can slide along gear Z1 (3), makes gear Z1 (3) rotate, thus change phase angle X size (see Fig. 8), concrete structure is gear Z1 (3) facewidth facewidth more than gear Z2 (4), and gear Z1 (3) is assemblied in main crankshaft (1) and above and leads to Crossing the fixing connection of spline, gear Z2 (4) is assemblied on secondary crankshaft (2) and is connected by spline slide, can slide back and forth on secondary crankshaft (2) Dynamic, gear Z1 (3) and the engagement of gear Z2 (4) helical gear, when gear Z2 (4) is movable under executor (22) drives, gear Z2 (4) and gear Z1 (3) is relative to slide, and promotes gear Z1 (3) to rotate an angle (see Fig. 8), and so, main crankshaft (1) and pair are bent The phase angle X of axle (2) just there occurs change, the change at phase angle, thus it is possible to vary the geometrical compression ratio of master cylinders, passes through electromotor ECU controls executor (22) and changes the phase angle X of double-crankshaft, changes the compression ratio of electromotor, at various load and rotating speed In the case of, allow maximum compression ratio is located closer to top dead centre as far as possible, can improve fuel efficiency, if it occur that pinking, suitable Reducing compression ratio when strengthening phase angle X, pinking will disappear, and another structure of the adjustment at phase angle is gear Z1 (3) edge Sliding axially, gear Z2 (4) fixes, and the facewidth of gear Z2 (4) is slided more than gear Z1 (3), gear Z1 (3) and made gear Z2 (4) Rotate an angle (see Fig. 9).

The third structure of double-crankshaft homogeneity compression-ignition engine (see Figure 11, Figure 12), is characterized in that major and minor bent axle is by three connecting rods Being connected with same piston, piston moves back and forth in cylinder, and air inlet system and exhaust system are identical with common engine, and concrete structure is main Bent axle (1) is connected with connecting rod I (31), and secondary crankshaft (2) is connected with connecting rod II (32), and the length of stroke of major and minor bent axle is identical, connecting rod I Equal with the length of connecting rod II, connecting rod I (31) and connecting rod II (32) are connected with connecting rod III (33) simultaneously, connecting rod III (33) again with piston (7) connecting, major and minor bent axle is connected by gear Z1 (3), gear Z2 (4), and gear Z1 (3) is assemblied on main crankshaft (1), the number of teeth Being assemblied on secondary crankshaft (2) for z1, gear Z2 (4), the number of teeth is z2, gear Z1 and gear Z2 engagement, z1: z2=1: 1, The contrary rotating speed of rotation direction of the most major and minor bent axle is identical, gear Z2 (4) facewidth facewidth more than gear Z1 (3), gear Z2 (4) Being assemblied in secondary crankshaft (2) above and to connect by spline is fixing, gear Z1 (3) is assemblied on main crankshaft (2), is connected by spline slide And can slidably reciprocate on secondary crankshaft (2), thus gear Z1 (3) can slidably reciprocate along gear Z2 (4), gear Z1 (3) and gear Z2 (4) helical gear engages, and when gear Z1 (3) is movable under executor (22) drives, gear Z2 (4) and gear Z1 (3) is relative Sliding, promote gear Z2 (4) to rotate an angle (see Figure 12), so, the phase angle X of major and minor bent axle just there occurs change, The change at phase angle, thus it is possible to vary the geometrical compression ratio (see Figure 13) of electromotor, controls executor (22) by Engine ECU and comes Change the size of the phase angle X of double-crankshaft, control the compression ratio size of electromotor, in the case of various load and rotating speed, Allow electromotor work under the conditions of most suitable compression ratio, fuel efficiency can be improved, if it occur that pinking, suitably reduce compression Ratio, pinking will disappear.

Accompanying drawing explanation

Fig. 1, Fig. 2 are the structure principle chart of double-crankshaft homogeneity compression-ignition engine, and major and minor bent axle passes through gear Z1 and gear Z2 Connecting, z1: z2=1: 2, auxiliary steam cylinder provides compressed air for master cylinders, and master cylinders does work, and the bent axle of the electromotor shown in Fig. 2 turns Dynamic direction is contrary with the rotation direction of Fig. 1.

Fig. 3 is another structure gear-driven of double-crankshaft homogeneity compression-ignition engine, and major and minor bent axle passes through gear Z1, tooth Wheel Z3 and gear Z2 connects, and z1: z2=1: 2, major and minor crank rotation direction is identical, and rotating ratio is 2: 1.

Fig. 4, Fig. 5 are the fundamental diagram of double-crankshaft homogeneity compression-ignition engine, and Fig. 4 is main piston top dead center position figure, Fig. 5 For auxiliary piston top dead center position figure, after secondary crankshaft turns over a phase angle X, main crankshaft turns over 2 phase angle X, maximum compression Than position under main piston top dead centre.

Fig. 6 is the stroke figure of double-crankshaft homogeneity compression-ignition engine, master cylinders complete air-breathing, compress, do work, four strokes of aerofluxus While, auxiliary steam cylinder completes compression and two strokes of air-breathing, and Fig. 6-1 is the ignition moment, when Fig. 6-2 has done work for master cylinders Carving, auxiliary steam cylinder air-breathing, Fig. 6-3 completes the moment for master cylinders aerofluxus, auxiliary steam cylinder air-breathing, when Fig. 6-4 completes for master cylinders air-breathing Carving, auxiliary steam cylinder compresses, and Fig. 6-5 has compressed the moment for master cylinders, and auxiliary steam cylinder compresses.

Fig. 7 is the top view of Fig. 1, and gear Z1 gear Z2 is assemblied on major and minor bent axle, and Z1 is assemblied in main crankshaft by spline On, gear Z2 is assemblied on secondary crankshaft by spline, and z1: z2=1: 2.

The second structure of Fig. 8, Fig. 9 double-crankshaft homogeneity compression-ignition engine, phase angle can change, gear Z1 and gear Z2 helical gear engages, and when gear Z2 is movable under executor (22) drives, gear Z2 is relative with gear Z1 to slide, Promoting gear Z1 to rotate an angle, the structure of Fig. 9 is that gear Z1 slides, and promotes gear Z2 to rotate.

Figure 10 is the schematic diagram that phase angle changes, and after helical gear Z2 slides axially a distance, helical gear Z1 is from a point Forward b point to, turn over angle Y.

Figure 11, Figure 12 are the schematic diagram of the third structure of double-crankshaft homogeneity compression-ignition engine, and major and minor bent axle passes through three companies Bar is connected with same piston, and major and minor bent axle is connected by helical gear Z1 and helical gear Z2, gear Z1 and the gear Z2 number of teeth Identical, gear Z1 slides along main crankshaft, promotes gear Z2 to turn over an angle, thus changes the compression ratio of electromotor.

Figure 13 is the schematic diagram that phase angle changes engine compression ratio, and gear Z1 and the engagement of gear Z2 helical gear, as gear Z1 When moving forward and backward under executor (22) drives, gear Z2 is relative with gear Z1 to slide, and promotes gear Z2 to rotate a phase angle X, the change at phase angle makes the position change of piston crown one height h, causes piston to change with the distance of cylinder cap, because of And the compression ratio of electromotor changes.

Detailed description of the invention

Double-crankshaft homogeneity compression-ignition engine operation principle: Fig. 6 is the stroke figure of double-crankshaft homogeneity compression-ignition engine, and master cylinders does to be inhaled Gas, compress, do work, while four strokes of aerofluxus, auxiliary steam cylinder does compression and two strokes of air-breathing, and Fig. 6-1 rises for master cylinders In the combustion moment, at this moment, the homogeneous charge in master cylinders is compression-ignited, and expansion stroke starts, until main piston arrives lower dead center is Only completing expansion stroke, Fig. 6-2 has done work the moment for master cylinders, and when master cylinders does work, auxiliary steam cylinder air-breathing, Fig. 6-3 is Master cylinders aerofluxus completes the moment, and hereafter, auxiliary steam cylinder piston continues traveling downwardly, until auxiliary steam cylinder arrives lower dead center auxiliary steam cylinder air-breathing Stroke terminates, and Fig. 6-4 completes the moment for master cylinders intake stroke, air during master cylinders air-breathing, in auxiliary piston compression auxiliary steam cylinder Entering master cylinders, Fig. 6-5 completes the moment for master cylinders compression stroke, but the now force value in master cylinders be not up to maximum, This rear master piston is descending, owing to the volume of auxiliary steam cylinder is more than the twice of master cylinders volume, although main piston is the most descending, but secondary The more compressed air that also has in cylinder goes successively to master cylinders, and the pressure in master cylinders is gradually increased, until master cylinders is descending During to two phase angle X, force value reaches maximum, i.e. maximum compression ratio point arrives, and maximum compression ratio point is cylinder compresses burning Final opportunity on fire, misses this point, electromotor will catch fire can not work by combustion, from main piston top dead centre to master cylinders This segment distance of big compression ratio point is referred to as ignition region, can light a fire without there is pinking by ignition at this region fuel oil.

The control system of double-crankshaft homogeneity compression-ignition engine: conventional engines maximum compression ratio is at the top dead centre of piston, it is necessary to accurately Controlling the position of point of origin, pinking the most just occurs, control system needs the most accurate；But due to twin crankshaft engine uniqueness Structure, maximum compression ratio is when auxiliary piston arrives top dead centre, and master cylinders just reaches maximum compression ratio, and now maximum compression ratio point Under main piston top dead centre, from main piston top dead centre to being all this electromotor in the interval of master cylinders maximum compression ratio point Ignition region, burning owing to main piston has moved downward then rough also will not produce pinking, and hcci engine can connect By overrich or the dilutest gaseous mixture, it is not necessary to accurately control the point of origin moment, ECU have only to control distributive value ensure not catch fire and Pinking, so long as not the denseest or the dilutest gaseous mixture, electromotor can normally work, control system almost with Normal engine is as broad as long, and for this electromotor, spark plug is dispensed with, without spark plug, it is simply that pure HCCI Electromotor, still retains spark plug, it is simply that double mode hcci engine, outside HCCI scope, uses spark plug point The mode of fire works.

The control of double-crankshaft homogeneity compression-ignition engine valve: owing to HCCI engine bandwidth of operation increases, be not up at electromotor Burning before maximum compression ratio falls within normal combustion, and this relates to a problem, it is necessary to control valve at most suitable point Folding, otherwise there will be problem, but when gaseous mixture is the denseest, firing point is the most top, if now inlet valve II is also in beating Open state, the gaseous mixture of burning can miss from secondary air intake duct, cause electromotor cisco unity malfunction, and efficiency declines, it addition, During the acting of master cylinders ignition, auxiliary piston still runs up, if the gases at high pressure now in master cylinders pour auxiliary steam cylinder, can lead The pressure caused in auxiliary steam cylinder steeply rises, and causes auxiliary steam cylinder engine knock even to be damaged, so the folding moment of inlet valve II must be controlled, In order to adapt to various operating mode, the method for control is: camshaft discharges inlet valve II in advance, at the latter end of compression stroke, inlet valve II belongs to free state, and the pressure by auxiliary steam cylinder air-flow is in the state opened, when the fuel oil in master cylinders burns in a flash, Pressure in master cylinders explodes, and inlet valve II is automatically switched off, it is to avoid master cylinders leaks gas；After inlet valve II closes, in auxiliary steam cylinder Pressure discharges nowhere, the power of meeting consumption of engine, so the camshaft of inlet valve I is preferably the camshaft of variable timing, After inlet valve II closes, open inlet valve I, the pressure in release auxiliary steam cylinder, it is to avoid the power of consumption of engine in advance.

The control of double-crankshaft homogeneity compression-ignition engine variable phase angle: the geometrical compression ratio of electromotor is adjustable, Engine ECU according to Concrete operating mode, by the position of executor (22) regulation helical gear Z2 (4), concrete structure is that bearing block (20) is by spline and gear Z2 (4) is fixing to be connected, and panel (21) is assemblied on bearing block (20) and is connected by bearing, and panel (21) is with executor (22) even Connecing, executor (22) promotes panel (21) to move forward and backward, and driven gear Z2 (4) slide anteroposterior changes the size at phase angle, logical Crossing the change at phase angle to change the geometrical compression ratio of electromotor, phase angle is the biggest, and the bandwidth of operation of HCCI is the biggest, burning effect Rate is the lowest, when fuel oil is when doing work close to the position ignition of maximum compression ratio, and the now the most descending segment distance of piston, acting Distance shorten, efficiency reduces, so for the fuel efficiency improving electromotor, control system to allow as far as possible fuel oil near on Certain position ignition acting of stop, such fuel efficiency can improve a lot, and phase angle the least HCCI bandwidth is the least, efficiency The highest, the risk of pinking simultaneously is the biggest, when detonation sensor is detected with pinking, suitably strengthens phase angle or suitable Reduce distributive value and can eliminate pinking.

Claims (4)

1. a double-crankshaft homogeneity compression-ignition engine, is characterized in that double-crankshaft homogeneity compression-ignition engine is by main crankshaft (1) and secondary crankshaft (2) Composition, has master cylinders and auxiliary steam cylinder, major and minor bent axle to be arranged under major and minor cylinder in cylinder body (9), main crankshaft (1) connects main company Bar (5), main piston (7) move back and forth in master cylinders, and secondary crankshaft (2) auxiliary connection connecting rod (6), auxiliary piston (8) are reciprocal in auxiliary steam cylinder Motion, major and minor bent axle is connected by gear Z1 (3), gear Z2 (4), and gear Z1 (3) is assemblied on main crankshaft (1), and the number of teeth is Z1, gear Z2 (4) are assemblied on secondary crankshaft (2), and the number of teeth is z2, gear Z1 (3) and gear Z2 (4) engagement, and z1: z2=1: 2, The rotation direction phase reversal speed ratio of major and minor bent axle is 2: 1, and main crankshaft (1) rotates 720 degree and completes air-breathing, compresses, does work, arranges While four strokes of gas, secondary crankshaft (2) rotates 360 degree and completes compression and two strokes of air-breathing, and cylinder cap (10) is positioned at major and minor vapour On cylinder, there are main air intake (16), secondary air intake duct (17), exhaust duct (18) in inside, by secondary air intake duct (17) between major and minor cylinder Communicating, and controlled the folding of secondary air intake duct (17) by inlet valve II (12), inlet valve I (13) is assemblied on main air intake (16), enters Valve II (12) is assemblied on secondary air intake duct (17), and exhaust valve (11) is assemblied on exhaust duct (18), and atomizer (14) is only toward in master cylinders Oil spout, auxiliary steam cylinder provides compressed air for master cylinders, and master cylinders is when acting and aerofluxus, and inlet valve I (13) opens, inlet valve II (12) Closing, air is inhaled into auxiliary steam cylinder from main air intake (16), and master cylinders is when air-breathing and compression, and inlet valve II (12) opens, air inlet Door I (13) is closed, and the air in auxiliary steam cylinder is compressed and passes through secondary air intake duct (17) enters master cylinders, and secondary crankshaft falls behind main crankshaft one Individual phase angle X, the volume of auxiliary steam cylinder is that the twice of master cylinders volume is many, a diameter of D1 of master cylinders, and length of stroke is L1, A diameter of D2 of auxiliary steam cylinder, length of stroke is L2, D1²·L1∶D2²L2 ＜ 1: 2, the position of maximum compression ratio is in main piston (7) Under top dead centre.

2. double-crankshaft homogeneity compression-ignition engine as claimed in claim 1, is characterized in that the second knot that major and minor bent axle connects Structure, is connected by gear Z1, gear Z3 and gear Z2, and the number of teeth of gear Z1 is z1, and the number of teeth of gear Z3 is z3, tooth The number of teeth of wheel Z2 is z2, z1: z2=1: 2..

3. double-crankshaft homogeneity compression-ignition engine as claimed in claim 1, is characterized in that the of double-crankshaft homogeneity compression-ignition engine Two kinds of structures, phase angle is variable, adjusts phase angle and changes the compression ratio of electromotor, and concrete structure is gear Z1 (3) facewidth More than the facewidth of gear Z2 (4), gear Z1 (3) is assemblied in main crankshaft (1) and above and connects by spline is fixing, and gear Z2 (4) assembles Secondary crankshaft (2) is connected by spline slide, can slidably reciprocate on secondary crankshaft (2), gear Z1 (3) and gear Z2 (4) helical gear Engagement, when gear Z2 (4) is movable under executor (22) drives, gear Z2 (4) and gear Z1 (3) is relative to slide, and promotes Gear Z1 (3) rotates an angle, and the phase angle X of bent axle (1) and secondary crankshaft (2) just there occurs change, by Engine ECU control Executor processed (22) changes the phase angle X of double-crankshaft, changes the compression ratio size of electromotor, another of phase angle adjustment Structure is that gear Z1 (3) slides axially, and gear Z2 (4) fixes, and the facewidth of gear Z2 (4) is more than gear Z1 (3), gear Z1 (3) Slip makes gear Z2 (4) rotate an angle.

4. double-crankshaft homogeneity compression-ignition engine as claimed in claim 1, it is characterized in that double-crankshaft homogeneity compression-ignition engine the third Structure, main crankshaft (1) is connected with connecting rod I (31), and secondary crankshaft (2) is connected with connecting rod II (32), and the length of stroke of major and minor bent axle is identical, The length of connecting rod I and connecting rod II is equal, and connecting rod I (31) and connecting rod II (32) is connected with connecting rod III (33) simultaneously, and connecting rod III (33) is again Being connected with piston (7), major and minor bent axle is connected by gear Z1 (3), gear Z2 (4), and gear Z1 (3) is assemblied on main crankshaft (1), The number of teeth is z1, and gear Z2 (4) is assemblied on secondary crankshaft (2), and the number of teeth is z2, gear Z1 and the engagement of gear Z2 helical gear, z1: Z2=1: 1, the contrary rotating speed of rotation direction of major and minor bent axle is identical, gear Z2 (4) facewidth facewidth more than gear Z1 (3), gear Z2 (4) is assemblied in secondary crankshaft (2) and above and connects by spline is fixing, and gear Z1 (3) is assemblied on main crankshaft (2), passes through spline slide Connect and can slidably reciprocate on secondary crankshaft (2), when gear Z1 (3) is movable under executor (22) drives, gear Z2 (4) Relative with gear Z1 (3) sliding, promote gear Z2 (4) to rotate an angle, the phase angle X of major and minor bent axle just there occurs change, The change at phase angle, thus it is possible to vary the geometrical compression ratio of electromotor.