US2408057A - Internal-combustion engine of the free piston type - Google Patents

Description

24,1946; o, M IQ v2,408,057 I INTERNAL COMBUSTION ENGINE-OF THE FREE PISTON TYPE Filed March 9., 194a 4.Sheets-Sheet 1 Fig. I 3" 4a '24 40 23 44 4/ 25 23 #50 3a 20 n F /l 22 a9 a1 NQENFQQ, Harold Owl-ridge Form m W d Sept. 24, 1946. H. o. FARMER I INTERNALCOMBUSTION ENGINE OF THE FREE PISTON TYPE Filed March 9, 1943 4 Sheets-Sheet 2 Wm M Sept. 24, 1946. o, FARMER 2,408,057

INTERNAL-COMBUSTION ENGINE OF THE FREE PISTON TYPE Filed March 9, 1943 4 Sheets-Sheet 5 10 Fig. 9.

VELNTOE -21 ATTY- Patented Sept. 24, 1946 INTERNAL-COMBUSTION ENGINE FREE PISTON TYPE {OF THE Harold Oatridge Farmer, Hounslow, England, as

signor to Alan Muntz & Company Limited, Hounslow, England, a company of Great Britain Application March 9, 1943, Serial No. 478,503 r In Great Britain March 2, 1942 i This invention relatesto internal-combustion engines of the free-piston type. The primary moving parts of such free-piston engines consist of a piston assembly or usually an opposed pair of such assemblies and the connecting linkage which constrains them to move in synchronism. These parts are unconstrained by any continuously rotatable crank-shaft, though the synchronising linkage may include a crank-shaft which is arranged to oscillate through a limited angle. Generally this angle is less than 180", so that neither the inner nor the outer dead point of the motion of the piston assemblies is fixed by the synchronising linkage. Dead points which are not so fixed will hereinafter be termed indeterminate dead points. In special cases the crank-shaft may be arranged to oscillate through an angle between 180 and 360, in which case one of these dead points is fixed by the synchronising linkage and the other is indeterminate.

The primary moving parts come to rest in the dead points, and for short periods on each side of indeterminate dead points the speeds of all these moving parts are relatively very low. Furthermore, with engines operating on a variable load, the positions occupied by these parts at indeterminate dead points vary with variation in the operating conditions of the engine. Consequently such moving parts cannot be employed directly to operate auxiliary mechanism, such for example as a fuel-injection pump of a compression-ignition free-piston engine, which is required to function at an accurately determined instant in the engine cycle at or near an indeterminate dead point.

An object of this invention is to provide an improved method and means of overcoming this difliculty.

According to this invention, an operation required to take place at a time including or near an indeterminate dead point in the cycle of a free-piston engine is performed by the agency of kinetic energy which is transferred from the primary moving parts of the engine during their acceleration and which is thereafter stored. during the subsequent retardation of such parts until the operation takes place.

A free-piston engine according to this. invention includes an inertia member operatively con-. nected to the primar moving parts of the engine in such a manner that the inertia member is accelerated by the motion of said parts during the first part of one of their strokes that precedes their occupation of an indeterminate dead point and is free-to overrun said parts during a 19 Claims. (01. 123-46) 1 ple as to operate a fuel-injection pump or to time I subsequent part of the same stroke, meansbeing provided which co-operate with the inertia member by retardinglit at a. predetermined point in such overrunning motion and using the kinetic energy thereby taken from the inertia member to perform an auxiliary function, such for examat least one of the limits of the delivery period of fuel-injection means.

Another object is to provide means for controlling the movement of the inertia member as it approaches each end of its stroke.

Anotherobject is to provide a compact and robust mechanism incorporating the inertia member and the means for driving it and for causing it to perform the auxiliary function.

Further objects and advantages of the invention will be apparent from the following description of an embodimentof the invention given with reference to the accompanying drawings, as

applied to the drive of'a fuel-injection pump of a two-stroke compression-ignition air-compressor of the opposed-piston type. In the drawings:

Fig. l is a diagrammatic sectional side elevation of the air-compressor, I

Fig. 2 is. a side elevation of part of the compressor shown in Fig. 1,. with part of the casing broken away and with the fuel-injection pump drive unit removed, a

Fig. 3 is an end elevation of the same compressor, some parts being shown in section on the line 3.-3 in Fig. 1,

.Figs. 4, 5, 6 and 7 show diagrammatically the fuel-injection pump and its drive mechanism in four different positions.

Fig. 8 is a graph (not to scale) illustrating the operation of this drive mechanism,

Fig. 9. isa sectional side elevation, taken on the lines 9-9 in Figs. 3 and 10, showing this drive mechanism in more detail,

Fig. 10 is a sectional end elevation taken on the line 10-10 in Fig. 9, and

cylinder 20 having inlet ports 2| and exhaust ports 22. A casing 23 surrounding the power cylinder. forms a scavenge air receiver communicating directly with the inlet ports 2|. At one end of the casing 23 is a compressor cylinder 24, and at the other end apneumatic cushion cylinder 25.

The primary moving parts of the compressor consist of two opposed free-piston assemblies and rod 33 to a cushion piston 3| operating in the" cylinder 25.

The synchronizing linkage includes t'wolevers 32 and 33 capable of oscillating equally and oppositely about their mid points on-acommon horizontal axis which is perpendicular'to the common longitudinal centre line of the two piston assemblies. The ends of the-lever 32are connected by connecting rods 34 and 35 respectively to two crossheads 36 and 31 fixed to the piston rods 21 and 30 and maintained horizontal by arms I 3.8 and 39 sliding in guideways 40 and 4| formed "thecasing' '23. The ends of the lever' 33' are likewise connectedbylconnecting rods 42 and" 43 respectively to the 'crossheads' 36 and 31.

A fuel injection' nozzle 44 is suppli'e'd'b'y a fuelin'jction pur'n'p45 of known' typefprdvided with the usual adjusting member 45 for'control' of the "quantity injected. Thecompressor cylinder 24 is "doubleacting; the outer face of the compressor piston 28 draws in air through inlet 'valves'such as"41 'and delivers it throughvalves such as 48 "to"a"conipressed'-air receiver (not 's hown),'while the inner face of this piston draws in scavenge fair through valves'such"as49i and delivers it to "the; scavenge 'air receiver through valvessuch as 50.

Figs. I and 2 show the compressor: at the inner dead point of the free pistons. During the ex- 'pan sion stroke of the power pistons, the synchronihinglevers 32 and 33 are first accelerated "counter 'clockwise and clockwise respectively as viewd-in'Figs. 1 and 2, and thereafter retarded, their angular velocity b'eing'roughly directly proportional 'to the linearvelocity 'of the free pistons. "When' the free pistons attain'theirouter deadpoint, the synchronising levers, will have Qbeendisplaced through roughly a right angle. -The"pow er 'cylinden'zfi havingibeen scavenged, the 'free' pistons execute their in stroke, under the influence of the energy stored, during their out stroke,'in the air compressed in the cushion cylinder 25 "andin the clearance volume of the outer end of the compressor cylinder 24, the synchrolevers32 and33 returning to the positions shown atan angular velocity varying roughly in direct proportion to the"'linear*velocity of the free pistons. I

The drive mechanism "forthe fuel-injection pump :45is contain'ed'in a case (Fig. 3) and is actuated by a pivot shaft 52 of the synchronising lever 33. Figs. 4 to 7 show this mechanism in different configurations, and it is convenient to refer to Fig. 6, Which-shows the configuration "at the inner dead point of the free pistons, correspondingto Figs. 1 and 2. A driver 53, shown fjdiagrammaticallyby heavyblack lines, is rigid '{with the shaft 52, so'that its angular velocity'is also'i roughly directly proportional tothe linear locity ofthe free pistons. "Iheinertia lever "54;,-whi'ch is arranged to move in a plane parallel to the plane of movement of the driver 53, has

oneend 'pi'votally connected at'55' to'the' driver "ata'point displaced from the axis of oscillation of the driver. Relative movement betweefi'the driver-53and the ineruaiever 54 'is limited by arrangingthe oscillating shaft '52to which the driver is fixed as an abutment passing with clearance through an eye 56 in the inertia lever. A weight 57 is rigid with the inertia lever 53 and is disposed on the side of the eye 56 remote from the pivoted connection 55.

The} axis of averticallydisplaceableEtappet 58 actuating the fuel-injection'pump '45is perpendicular to the axis of the shaft 52, and is roughly perpendicular to the longitudinal centre line of "the driver '53when the latter is in the position "shown in Fig. 6 corresponding to inner dead point at full load. The tappet 58 is so connected to the inertia lever 54that it is constrained to follow the verticalco'rnponent of the displacement of the point on the inertia lever that traverses the axis of oscillation of the driver. Thus the tappet "is coupled to the inertia lever by a connecting link-fifl one end of which is carried on a ring journal 63 co-axial with the eye 56 in the inertia lever and the other end of which is pivotallycon- 'nected at'fil to the tappet, I

The buffer for checking themovement of the inertia lever'54 at the end of the stroke in which fuel injection'occurs, consists of "a laminated cantilever spring 62, fixed to the driver53 and positioned to be engaged by a pin 63 on the inertia lever as the latter comes near to one end of its displacement relative to the driver.

The buffer for checking the movement of the inertia lever in the opposite sense is a hydraulic dash-pot device having one element 64 mounted on the driver and the other element 65 coupled toa pin 66 on the inertia lever by a connection Ei providing lost motion, the arrangement :being such that the dash-pot imposes a resistanceto the movement of the'inertia lever relative to the driver as the former comes near to the other end of its displacement.

"The fuel injection pump has an inlet port 68 controlled byits plunger 63, which is urged in the direction of its suction stroke by a spring 35. During the delivery stroke of the plunger, after the-inlet port 58 has closedi fuelis delivered through a non return valve ll until a spill port 1 12in the plunger -comes=into register with'a spill port lt in the pump body; thus relieving the delivery pressure.

The operation of the'ffuel-pump drive mecha- -nism will be described'with reference to the graph in Fig. 8,in whic'hare plotted, on a time base showingbne complete cycle from anouter dead Fe. and

--Angularacceleration of the inertia lever denoted by'Fw.

' At the outer dead point of the -free pistons (OLD'LP inFig. 8) the driver 53 isstationaryin the position shown in" Fig. 4- and it has a high acceleration in a positive sense (counterclockwise asfseen in Fig. 4); and the inertialever '54 is "atwhat' will be termed the trailing limit of its range of movement relative'tothe driver.

The

driver therefore accelerates the inertialever up to its' maximum angular velocity (ii in Fig. 8).

When. the acceleration of the driver becomes negative," which "occurs early in "the'second "half orthe compression stroke, the weight 51 on the inertia lever continues to move at an angular velocity whichfalls relatively slowly, with the has moved through a predetermined distance, the

fuel-injection period commences, at time 152 in Fig. 8, the power required to actuate the pump being supplied by the kinetic energy of the weight 51 which is thereby retarded. Fig. 5 shows the configuration at the beginning of the fuel-injection period; 'I'he'fuel-injection period continues while the'pistons pass through inner dead point (Fig. 6), until the tappet has advanced through the further distanc required to open the spill ports 12; and 13. The end of the fuel-injection period occurs at time is in Fig. 8. Thereafter the weight '51 continue to move at a substantially constant velocity for a short distance. At time ii in Fig.

8, before the inertia lever has reached the leadinglimit of its range of movement relative to the driver, the buffer spring 62 is engaged by the pin 63 and the weight is accordingly subjected to a short but high negative acceleration. The weight is thereby arrested and immediately moved at a "rapidly increasing velocity in the opposite direction.. When the inertia lever disengages from the buffer spring at time is in Fig. 8, the weight continues to. move at a substantially constant velocity, catching up the driver. In the latter half of. the expansion stroke the driver is again sub- 'ject' to acceleration in the positive sense, and at time is inFig. 8 the pin 66 takes up the lost motion in the connection 61 (Fig. 7) and the inertia lever is prevented by the dash- pot device 64, 65, from returning with excessive shock to the trailing limit of its range of travel relative to the driver. The inertia lever and the driver begin to move inunison again at time is in Fig. 8.

- Figs. 9, 10 and 11 show the fuel-injection pump drive mechanism in greater detail, the configuraition being-that at inner dead point at full load of the air compressor. The pivot shaft 52 of the synchronising lever 33, which oscillates in synchronism with the engine pistons, is journalled at 14in the case 5| and at 15 in a cover 16 of this case. The driver 53 has a hub portion 11 provided with internal splines engaged with a splined portion of the shaft 52, so that the driver 53 and the lever 33 are constrained to oscillate in unison. Oil under pressure is admitted at a union 1B in the cover 16 and flows, through a bore 19 and a port 80 in the shaft 52, and through a non-return valve 8! and a duct 82 in the driver 53, to the cylinder 64 of the dash-pot device. Sinc oil can flow freely into the head of the dash-pot cylinder, the device imposes no resistance to outward movement of its piston 65. This piston is hollow and its head is provided with a leak port 83 co-operating with a tapered needle 84 fixed to the cylinder head. This port opens into a hollow non-return valve 85, and an exhaust port 86 in the piston registers with an exhaust port 8'! in the cylinder. The non-return valve 85 prevents air from being sucked into the dash-pot cylinder during outward movement of its piston. During inward movement of the piston the oil trapped in the cylinder by the non-return valve 8| is forced to flow through the leak port 83 and the valve 85, and

the needle i so shaped as to vary the effective .area, of the leak in accordance with the relative displacement of the piston 65 and the cylinder 64,

respectively two weight 51A and 51B which are 10 bridged by the pins 63 and 66. Each of the arms 54A and 54B is provided with a hollow boss (Fig.

0) the interior surface of which forms the eye 56 that co-operates with the shaft 52 to limit the relative displacement of the inertia lever and the driver; the exterior surfaces of these Ibosses form the ring journals for the big ends of twin connecting rods 59A and 59B actuating the fuelpump tappet 58.

The buffer spring 52 that is mounted on the driver is supplemented by a pair of buffer springs 88A and 88B which are mounted on the case 5| and which co-operate with lugs 89A and 893 formed on the rods 59A and 59 The mechanism described by way of example has the advantage that it can be designed to operate with standard types of fuel-injection pumps that are now commercially available.

The'invention may be similarly applied to a timing device for determining the beginning or the end or both of a fuel-injection period in a free-piston engine having a fuelinjection device, the pump of which is operated by means other than the inertia member, such" for example as a small gas motor energised by the working fluid compressed in the engine combustion chamber, such as described for example in my co'pending U. S. patent application Serial No. 376,259, filed January 28, 1941, now Patent No. 2,351,414, June 13, 1944.

I claim: i 1. An internal-combustion engine having a power cylinder, a compressor cylinder, primary moving parts including a power piston and a compressor piston co-operating with said cylinders respectively and connected together for operation in unison as a free-piston assembly capable of reciprocating through a variable stroke, such that at least one of its dead points is indeterminate, an auxiliary member for performing a function auxiliary to the operation of said engine, an inertia member, an operative connection between said inertia member and said primary moving parts for imparting to said inertia member an acceleration by the motion of said parts during the first part of one of their strokes that precedes their occupation of said indeterminate dead point, said connection serving to permit said inertia member to overrun said parts during a subsequent part of the sam stroke, and means operatively associated with'said auxiliary member and capable of co-operating with said inertia member by retarding it at a predetermined point in such overrunning motion and using the kinetic energy thereby taken from said inertia member to actuate said auxiliary member.

2. An internal-combustion engine having a power cylinder, means for injecting fuel into said cylinder, a compressor cylinder, primary moving parts including a power piston and a compressor piston co-operating with said cylinders respectively and connected together for operation in unison as a free-piston assembly capable of reciprocating through a variable stroke such that the minate, an inertia member, an operative connec- .tion between said 1 inertia member and said primary .moving parts i or imparting to a, said inertia fimember an accelerationi v th m t on ,of s id parts during, the firstpart-of one ftheir strokes that precedes their occupation of said indeterrninate dead point, said connection serving to permit said inertiamember to overrun said parts during a subsequent part of the same stroke,an d means operatively associated with said ,iuel-injection means and capable 10f cooperating with .said inertiajmember byretardingit at a predeltermined'pointin such overrunning motion and usingthe kinetic energy thereby taken from said inertia member to .actuate said iuel-injection lmeans.

.,3. An internal-combustion engine having a power ;cylinder, a systemjior injecting fuel into said cylinder, said system including means for ,timing at least one or the limits of the. delivery period of said system, a cmpressor cylinder, pri- ;ma ry moving parts including apower; piston and ;a compressor piston co-operating with said cylinders respectively and connected together for op- :eration in unisonas a free piston assembly capable ofrreciprocating through a variable stroke, such thatthe inner dead p int of said power piston is indeterminate, an inertia member, an op- ;erative connection between said inertia member and said primary moving parts for imparting t0 ;saidiner tia member anaccelerationby the mo-- tionrof said partsduring the first part of one of theirrstrokes that precedes their occupation of said indeterminate dead point, said connection serving, to permit said inertia member to overrun said parts duringa subsequent part of the same stroke, and means operatively associated with said timing means and capable of co-operating with said inertia member by retarding it at a predetermined point in such overrunning motion, and using the kinetic energy thereby taken from said inertia member to. actuate said timing a w l i .7

4fAn .internal-combustionengine having a ,powericylinder, a compressor 'cylindenprimary moving parts including a power piston and a compres's'or, f piston eta-operating with said cylinders respectively and cdnhfl'fid together for operation n. unison as a nee-piston assembly capable of reciprocating'j through a variable stroke such that at least oneof'its dead points is indeterminate, .an'auxiliary, member for performing a 'function ,auxiliary tothe ope rationof said engine, anos'cilliable inertia member, an operative connection between saidinertia member andsa'id primary gmoving partsifor'impartingto said inertia mem- "ber an acceleration 'bythe'rnotion of said parts sdur'i'ngthefirst part of one of their strokesthat precedes their occupation of said indeterminate dead point, said connection servingto permit sjai'd 'inertia member to overrun said partsfdurfinga subsequent part of migraine stroke, means operatifvelyjassociated with said auxiliary 'inemher and capable of co-operatirig with said inertia lfrnember'bj retarding at a predetermined point in such overrunning motion; and using the kinetic energy, thereby taken from said inertia member 'to actuate said auxiliary memberand at least one buffer for checking movement of said inertia "member as it approaches each end. of its stroke.

5. An internal-combustion engine..;havi ng a power cylinder, a compresso cylinder, primary moving parts including'ia pow ertpiston and a com prelssor piston co-operating with said cylinders iw ll ye 1il dmg ihs r, o rati ml si n, c se l is pietona emb ram e; o r

reciprocatingthrough a variable stroke-such that at least one of its-dead points is indeterminate, an auxiliary member for performing ,a function auxiliary ;to the operation of said engine; an oscillable: inertia ;member, an operative connection including-an oscillatory driver between said inertia member andsaid primary moving-parts for imparting to said inertia member an acceleration. bythe motion of said partsduringthe first part of one of their strokes that precedes their occupation of said; indeterminate-dead point; said driver providing lost motion-gtopermit said inertia member to overrun said parts during .a;subsequent part of the same stroke, means operatively associated with said auxiliary member and capable of co-operating with-said inertiamember-by retarding .it at a predetermined point in such overrunning motion and usi gthe kinetic' energy thereby taken from said'inertia member toactuate said auxiliary member-and .at" least one buffer arranged to reactyon-said oscillatory driver for .checking movement of, said inertia; memberas it approaches each'end of its stroke: r 66. An internal-combustion "engine havingv ;a power cylinder, a compressor cylinder,-primary moving parts including a' power piston and ,la compressor piston cooperating :with said cylinders respectively and connected together for operation in unison asafree-piston assembly capable of reciprocating throughavariabl'e troke such that at leastjone of itsf'dead points, iSLindeterminate, an' auxiliary member forperforming a function auxiliary to the operation of said engine, an oscillable inertia member, an operative connection including an oscillatory driver between said inertia member and "saidprimary moving parts for imparting to said inertia member an acceleration bythe motion'ofsaid-parts during'the first part of one or their strokes'that precedes their occupation of said indeterminate dead point, saiddriver providinglost motion to permit said inertia member to overrun said'parts during a subsequent partof'the" same stroke, means operatively associated with said auxiliary member and capable of co-operating .withsa'id inertia member by retarding it-at a'predetermined point in such" overrunning 'motionx-and using the kinetic energy thereby taken from said inertiamember to actuate said auxiliary member, and a resilientbuffer arranged: to react" on said oscillatory driver for :checking such: overrunning motion of said, inertia member relative 'to .said .oscillatory driver.

' '7. An internal-combustion engine having a power cylindena compressor cylinder;-primary moving parts including a'power piston" and a compressor piston co-operating with said cylinders respectively andconnectedv together for-operation in unison asa free-piston assembly capable of reciprocating'througha variable: stroke, such that at least one-of its dead points .is-indeterminate, can; auxiliary member for perform- 'ing' afunction auxiliary to rthe'operatiorl'of said engine, an oscillable inertia member, an operative connection including an oscillatory driver-between said inertia a member-"and 'said primary moving parts fori'imparting to said inertiarnei'hber' an accelerationiby the motion-of said parts during the first part of one of their strokes-that precedes their occupation of said indeterminate "dead point, said driver providing lost "motion-Ito permit said'inertiamembe'r'to overrun said parts during: a subsequent partxofi thie -same stroke, means operatively: associated with said auxiliary member :and capable of:- co-operatin'gWithsaid :19' inertia member by retarding it at a predetermined point-in suchjoverrunning motion and using the :kinetic energy thereby taken from said inertia member to actuatefsaidauxiliary member, a resilientbuifer arranged to react on said oscillatorydriver for checking such overrunning motion of said inertia member relative to said oscile latory driver, and a buffer in the'form of aflfluid dash-pot device arranged to react on said oscillatory driver for checking the returnmotion imparted to said inertia member by said resilient buffer. 8. An internal-combustion engine having a power cylinder, a compressor cylinder, primary moving parts including a powerpiston and a compressor piston co-operating with said cylinders respectively and, connected together for operation in unison asxa ,free-piston .as'semblycapable of reciprocating through a variablestroke such that at least one of its dead points is indeterminate, an auxiliary member' for performing a function auxiliary to :the operation of said engine, an oscillable inertia member, an operative connection including an oscillatory driver between said inertia member and said primary moving parts for imparting to said inertia member an acceleration by the motion of said parts during the first part of one of their strokes that precedes their occupation of said indeterminate dead point, said driver providing lost motionto permit said inertia member to overrun said parts during a subsequent part of the same stroke,

means operatively associated with saidauxiliary member and capable of co-operating with said inertia member by retarding it at a predetermined point in such overrunning motion and using the kinetic energy thereby taken from said inertia member to actuate said auxiliary member, a resilient buffer arranged to react on said oscillatory driver forchecking such overrunning motion of said inertia member relative to said oscillatory driver, and a bufier in the form of ,a fluid dash-pot device arranged to react on said oscillatory driver for checking the return motion im-, parted to said inertia member by said resilient buffer, said dash-pot devicehaving an automatically variable leak calibrated to maintain a substantially uniform resistance as the relative speed of said inertia member and said oscillatory driver falls.

9. An internal-combustion engine having a power cylinder, a compressor cylinder, primary moving parts including a power piston and a compressor piston co-operating with said cylinders respectively and connected together for operation in unison as a free-piston assembly capable of reciprocating through a *variable stroke such that at least one of its dead points is indeterminate, an auxiliary member for performing a function auxiliarytothe operation of said engine, an oscillable inertia member, an operative connection including an oscillatory driver be tween said'inertia member and said primary moving parts for imparting to said inertia memher an acceleration by themotion of aid parts during the first part of one of their strokes that precedes their occupation of said indeterminate dead point, said driver providing 10st motion to permit said inertia member to overrun said parts during a snbsequentpant of the same stroke, means-toperatively associated with said auxiliary member and capable of ,co-operating with said,

inertia member by retarding ittat a predetermined pointQinsuch overrunnin motion and using thekinetic energy therebytaken, from said 10 inertia'member to actuate said auxiliary member, a resilient buffer arranged to react on said oscillatory driver for checking ,such overrunning motion of said inertia member relative to said oscillatory driver, a stationary part,'and a supplementary buiier arranged to react on said stafor checkin said overrunning mobetween said inertia member and said, primary.

moving parts forimparting to said inertiamemher an accelerationby' the motion of said parts:

during the first part of 10116 of their strokes that precedes their occupation of said indeterminate dead point, said driver providing lost motion to permit said inertia member to overrun said parts during a subsequent part of, the, same stroke, means operatively associated with said auxiliary member and capable of co-operating with said inertia member by retarding it at -a predetermined point in, suchl overrunning motion, and using the kinetic energy thereby taken fromsaid; inertia" member to actuate said auxiliary ,mem-, ber,- a, resilient buffer arranged to react on said oscillatory driver for checking such overrun: ning motion of said inertia member relative to; said oscillatory driver, a bufier inthe form oi a fluid dash-pot device arranged to react on said oscillatory driver for checking the return-motion imparted to'said inertia member by said resilient buifer, a stationary part, and a supplementary buffer arranged to react 1on said stationary part for checking said overrunning motion. M 11. An internal-combustion engine -having;a power cylinder, a compressorcylinder, primary moving parts including a powerpistonand; a compressor piston co-operating with said cylinders respective1y,'and connectedtogether forpp-l eration in unison as a free-piston assembly cap a-;

ble 'of reciprocating through a. variable stroke such that at least one of its dead points is inde terminate, an auxiliary memberior perforininga function auxiliary to the operation of saiden gine, an oscillatory driver operatively connected with said primary moving parts, an inertia mem-, her in the form of a relatively massiveleverwhich is pivotally connected to said oscillatory driver in such a manner that at such pivotal con nection said lever is reciprocated substantially transversely to its length, means for limiting displacement of said lever relative to saidoscilla tory driver, and, means operatively associated. with said auxiliary member, and capable ofco-' operating with saidlever by retarding its motion, and thereby transferringenergy fromsaid lever to actuate said auxiliarymember.

12. An internal-combustion engine having a power cylindena compressor cylinder, pri r moving parts including a power piston and a,

compressor piston co-operating with said cylinders respectively and connected together for operation in unisonas a free-piston assemblycapa ble of reciprocating through a Variable stroke,

such that atleast one of its dead points 'is 11 determinate," an auxiliary -memberfor-performing a' function auxiliary totthe operationpf said engine, an 'oscillatory driver' operatively: connected with said primary moving-parts, an in ertia member in the-form" of a, relativelymassive' 1 lever which is pivotally connected to said "oscillatory driver in such'a manner that at such'pivotal connection said lever is reciprocated substantially transversely to its length, means for limiting displacement of. saidlever relative to s'aid'oscillatory driven-and means operatively associated with said auxiliary member and, pivotally connected to apoint on said lever located between said pivotal connection and-the free end of said. lever, said last-mentioned means being responsive .to" transverse displacement of said point for transferring energy from said lever to actuate said auxiliary member;

1-3. An internal-combustion engine having a power cylinder, a compressor cylinder, primary moving parts including a'p'ower piston and a compress'or piston co-operating with a said cylinders respectively-and connected together for operation in unison' as a free-piston assembly capable of reciprocating through 'a variable Strke,'such that at least one of its :dead'points isindeterminate, anauxiliarymember for performing afunction auxiliary to the operation of said engine, an oscillatory crank having'a crank' p-in and operatively connected with 'said' primary-moving parts, a relatively massive lever pivotally mounted on the pinof said crank 'With' itsfree end projecting beyond the axis of saidcrank on the side thereof QDPOSit to saidpin, meansfor limiting displacem'ent -of said lever relative to said crank, and means for 'operativelyconnecting' said auxiliary member and said leverand capable of following acomponent of the motion of a point on said lever that is capable of coinciding'with the axis o'f's'aid crank; i V 14; An internal-combustion engine having a power-cylinder, a compressor cylinder, primary moving parts including a-power piston and a compressorpist'on 'co operating with said cylinders respectively and connected together for operation in unison as a free-piston assemblycag pable of reciprocating through a variable stroke, such that at least one of its deadpoints is indeterminate,'- an oscillatory auxiliarymember for performing a 'f'unctionauxiliary to the operation of said engine, anoscillatory crank having a crank pin and operativelyconnected with said primary moving parts, a relatively massive lever V pivotally mounted onthe p-in' of-saidcrank with its free end=projecting beyond the axis of said crankon the side'there'o'f opposite to said pin, means for-limiting=displacement of said lever relative to said crank; and a member connecting with said auxiliary member and pivotally connected-tosaid lever at an axis capable of coin cidingwith the axisof said crank. r

' 15.jA1'1 internal-combustion engine having a power cylinder,a compressor cylinder, primary moving parts including a power piston and a compressor piston co-operatingwith said cylinders respectivelyand connected together for operation in unison as a free-piston assembly capable of reciprocating through a variable stroke such that at least one of its deadpoints is indeterminate, an oscillatory auxiliary'member for performing a" function auxiliary to the operation of said engine, an oscillatory crank having a crank pin .and' operatively connected with said primary moving parts,"a relatively massive lever pivotally mounted on the pm of said crank with its-free end projecting beyond the axis of said crank on" the side thereof opposite to saidpin an abutment member: co-axial with said crank, a ring journal'rigidwith said lever and forming an 'eye co-operating with said abutment member for limiting angular displacement of said --lever relative to said crank,-and a'linkconnecting said auxiliary member to said ring journal. 1

4 1-6. An internal-combustion engine having a power Gy1inder, a compressor cylinder, primary moving parts including a: power piston anda compressor piston co-operating with said: cylinders respectively and connected together for operation in unison as a free-piston assembly capable of reciprocating-through a variable stroke such that at least one of its dead points-is in: determinate, an auxiliarymember for performing a function auxiliary to the operation of said en-v gine, an-oscillatory crank having a crank pin and operatively connected with said primary moving parts, a relatively massive lever pivotally mounted-on the pinof 'said crank .with its free end projecting beyond the axis of said crank on the side thereof opposite to said pin, meansfor limiting displacement of said' lever relative to said crank, and means for-operatively connecting said auxiliary member and said lever and capable of following a component ofthe motion of a point on said lever that is capable of coinciding with the axis of said crank, the'relationship of said crank to said primary moving parts being such that said last-mentioned-meansare arranged to be displaced substantially normally to a plane containing the'axes-of said crank and its pinwhen said crank is inthe position corresponding to anindeterminatedead point.

Y 17. An internal-combustion engine having a power cylinder, avsystem-for injecting fuel into said cylinder, said system including means for timing at leastoneof the limits of the delivery period of said system, a compressor cylinder, pri-i mary moving parts including a power piston and a compressor piston co-operating with said cylinders respectively; and connected together for operation in unison as .a free-piston assembly capable of reciprocating through a zvariable stroke such that the inner dead point of said power piston is indeterminate, an. oscillatory crank having a'cranklpinand operatively connected with said primary moving parts, a relatively massive .lever pivotally mounted on the pin of said crank with its free end projecting beyond the axis of said crank on the;s-ide thereof opposite to said pin, means for limiting'displacement of said lever. relativeto, said crank;, =and mean primary moving parts includinga power piston and a compressor piston co-operating with said cylinders respectively and connected together for operation in unison as a free-piston assembly capable of reciprocating through a variable stroke,

and means connecting said fuel-injection pump and said lever and capable of following a component of the motion of a point on said lever that is capable of coinciding with the axis of said crank, and thereby imparting to said pump a control movement from said lever While it is overrunning said crank during the latter part of the stroke of said pistons immediately preceding their occupation of said indeterminate inner dead point.

19. An internal-combustion engine of the free- 14 an indeterminate dead point, a driver operatively connected with said piston, an inertia member co-operating with said driver for receiving acceleration therefrom during the first part of a stroke immediately preceding said indeterminate dead point, and means for performing an operation auxiliary to the working of said engine, said inertia member being capable of imparting motion to said last-mentioned means during the second piston type as hereinbefore defined having a 10 part of said stroke.

power cylinder, a power piston slidable in said cylinder through strokes of variable length with H. O. FARMER.

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