GB2039611A

GB2039611A - Using exhaust gas expansively in inoperative cylinders of a Otto or Diesel cycle internal combustion engine

Info

Publication number: GB2039611A
Application number: GB8000703A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-01-09
Filing date: 1980-01-09
Publication date: 1980-08-13
Also published as: IT7967036A0; DE2952198A1; JPS566037A; IT1118270B

Abstract

An internal combustion engine, comprising cylinders (1-4), intake valves (9-12), exhaust valves (13-16), and exhaust ducts (5-8), includes an auxiliary duct (21) connecting the exhausts of the cylinders, valves (22,23) located in the exhausts of two of the cylinders (1,4) allowing exhaust gas therefrom to pass either through the respective exhaust duct or into the auxiliary duct, the engine being operable conventionally with valves 22,23 in position 22',23' or in an alternative manner wherein the intake valves (10,11) and the discharge valves (14,15) of the cylinders (2,3) are fixed to be closed and open respectively, the valves (22,23) in position 22'', 23'' so as to direct exhaust gas into the auxiliary duct, said exhaust gas acting expansively in the cylinders (2,3), the rotatable valves (26,27) being closed, and then being expelled from the cylinders (2,3) through the discharge ducts (6,7) the rotatable valves being open. The valves are driven at half crank shaft speed. <IMAGE>

Description

SPECIFICATION Otto or diesel cycle internal combustion engine This invention relates to an Otto or Diesel cycle internal combustion engine.

It is well known that the specific consumption in a reciprocating internal combustion Otto or Diesel cycle engine increases greatly with decrease of the delivered power with respect to the highest power which may be delivered by the engine.

It is equally known that, in town running requiring a lower power, pollution problems connected with the greater quantity of unburnt gases arise.

It is therefore desirable, to limit the specific consumption and the pollution, to utilize the engine at a speed which is the nearest possible to its maximum power, which almost never occurs in normal use.

A great deal of experimental studies have been carried out to try to overcome this drawback, and the latest studies follow substantially the following directions.

The first of these directions comprises utilizing two different engines on the same vehicle. When the vehicle requires a low power, it is actuated by only one of the two engines while the other remains at a standstill and disconnected from the transmission.

When a greater power is required, the two engines are connected together. A subsequent modification of this solution is the so-called "modular engine" wherein it is possible to exclude from operation and stop (by disconnection) one or more pistons according to the required power.

All the devices constructed according to this principle are however characterized in that the non-utilized pistons are stopped and consequently disengaged from the remainder. This provides the certain advantage that the inactive cylinders dissipate no power.

This solution therefore presents undeniable advantages from the point of view of efficiency, but it involves a complicated construction and higher production costs since it is necessary to utilize two separate engines orto resort to complicated systems which permit one or more cylinders to be disengaged from the motion in the case of the "modular" engines. Furthermore, this solution is not easily applicable to the engines of the traditional type as it requires substantial engineering modifications which may be carried out only with considerable technical difficulty.

The second of the above-mentioned development directions comprises the elimination, when a reduced power operation is required, of the combustion in one or more cylinders, without disengaging the motion of their pistons from the kinematic motion of the engine. This result may be obtained by keeping the inlet and the exhaust valves of the inactive cylinders closed.

Another possible variant, involving less constructional complications with respect to the preceding, comprises the simple locking of the fuel inlet in the inactive cylinders, without any variation of the respective valve operating cycle.

Both these solutions provide very modest improvements in efficiency, since the inactive cylinders, which are dragged by the others in the crank mechanism motion, dissipate a considerable energy due to friction and to the pumping effect. Further, remarkable temperature gradients occur in the engine between the active and the inactive cylinders and very different wear is noticeable between the cylinders having the two different functions.

In order to partially eliminate these drawbacks, experiments have been carried out on engines wherein the discharge gases of the active cylinders are passed in the suction conduits of the inactive cylinders and these latter suck the gases through their intake valves, operating as in the normal cycle.

The gas expansion may thus in some way continue within the inactive cylinders, recovering a portion of the power and making the temperature and the wear uniform. The recycle of the discharge gases as above described by their passage through the intake valves of the inactive cylinders presents the advantage of great constructional simplicity, but it causes considerable limitations and drawbacks. In effect, the ducts for the connection between the discharge of the active cylinders and the intake of the inactive cylinders are of considerable length, thus limiting by the dead space the expansion work which may be obtained from the gases.

Further, it is not possible, due to the unvaried phasing of the intake and discharge cams of the inactive cylinders, to obtain the maximum expansion of the gases within these cylinders in order to recover the whole work quantity which would be recoverable.

The present invention provides an Otto or Diesel cycle internal combustion engine, comprising at least four cylinders each having an intake valve, a discharge valve, and a discharge duct, an auxiliary duct connecting the exhausts of the cylinders, valves located in the exhausts of two of the cylinders so as to allow exhaust gas therefrom to pass either through the respective discharge duct or into the auxiliary duct, and rotatable valves located in the exhausts of two other cylinders, the engine being operable normally wherein the exhaust from each of the cylinders passes through the respective discharge duct or in an alternative manner wherein the intake valves and the discharge valves of the said two other cylinders are fixed to be closed and open respectively, the valves located in the exhausts of the first-mentioned cylinders are arranged to pass exhaust gas therefrom into the auxiliary duct, and the valves located in the exhausts of the said two other cylinders are rotated, whereby exhaust gas from a first-mentioned cylinder passes into the auxiliary duct, into and out of the said other cylinders while the rotatable valves are closed, and then through the discharge ducts of the said other cylinders when the rotatable valves are open.

Thus there is provided a multi-cylinder, particularly a four-cylinder, Otto or Diesel cycle, internal combustion engine, which is modified without particular constructive difficulties and which may be utilized under two different manners of operation, the first of which is the normal operation while the second allows, when the delivered power is considerably lower than the maximum, higher efficiency values (and therefore lower specific consumptions) to be obtained with respect to those obtainable in conventional engines as well as by means of the previously described known devices, particularly reducing the losses within the inactive cylinders.

It is also possible to improve the engine characteristics concerning the unburnt gases and to provide better uniformity in the distribution of the engine inner temperatures and in the wear of the cylinders, compared to the previously known devices.

In the economical running conditions of the engine according to the invention, the discharge gases of the cylinders wherein the normal combustion begins and takes place pass out through the respective discharge valves of the cylinders and are directed along the auxiliary duct and from there, through permanently open discharge valves of the cylinders wherein no combustion takes place, enter into the latter cylinders and achieve their complete expansion and produce thereby useful work. Finally the discharge gases, pushed again by the reascending motion at the top dead center of the cylinder pistons, return to the auxiliary duct and from there they have an open passage to the exhaust manifolds.

The invention will be further described, by way of example only, with reference to the accompanying drawings, in which: Figure lisa diagram of the theoretical thermal cycle of an Otto cycle internal combustion engine, with the variation which may be obtained by means of the present invention; Figure 2 is a diagram of the theoretical thermal cycle of a Diesel cycle internal combustion engine, with the variation which may be obtained by means of the present invention; Figure 3 is a schematic sectional view, along a plane normal to the cylinder axes, of a four cylinder, four-stroke-cycle internal combustion engine according to the invention; Figure 3a is an enlarged view of a part of the construction shown in Figure 3; Figure 4 is a sectional view taken along the line y-y in Figure 3a; and Figure 5 is a side view of the construction shown in Figure 3.

As shown in the drawings, a normal internal combustion engine is provided with a modification which becomes an integral part of it and allows the engine to operate according to two different alternative rates. The first of these rates will be indicated in the following as the "normal rate" while the second will be indicated as the "economical rate". The transition from one to the other of these rates may be arbitrarily decided by the driver of the motor vehicle, by actuating an appropriate control, accord ing to the traffic conditions and the running and drive requirements he intends to conform to, or may be automatically effected. In the latter case one or the other rate is automatically selected by a small control exchange which processes the various run ning and operating parameters of the vehicle.The "normal rate" concerns the operating conditions known and normally utilized in the common Otto and Diesel cycle engines. Therefore, one of the advantages of the present invention is that it may be easily applied to conventionally constructed engines by effecting on them some modifications which are not fundamental but permit the "economical rate" conditions to be obtained.

The "economical rate" is characterized in that during such operation two or more cylinders (which during the "normal rate" are regularly utilized in the usual manner) are vice versa used together in order to complete the expansion of the gases begun in the remaining active cylinders (the operation of which is conventional), as these gases, leaving through the discharge valves of the active cylinders, enter the cylinders wherein they achieve their complete expansion through their discharge valves and are thereafter again passed in the exhaust duct through the same discharge valves of the expansion cylinders which remain constantly open.

In other words, in the case of a four cylinder engine, during the "economical rate", two cylinders continue in their conventional mode of operation while the remaining two cylinders are utilized to prolong the expansion of the gases coming from the other two cylinders where the combustion takes place. There is effected, therefore, a phased transfer of the gases from the cylinders wherein the combustion takes place (which are utilized as in the "normal rate") to the cylinders which, differently from when they are utilized in the "normal rate", serve in this case only to prolong the expansion of the gases that they receive.Since in a four cylinder engine the cylinders selected as the expansion cylinders are the two wherein the pistons have a symmetrical motion (that is they reach at the same time the top dead center) while only one at a time of the two cylinders wherein the combustion begins (which also are symmetrical in their motion) is in the discharge condition, it follows that the expansion may occur, while producing useful work, until a volume is reached which is double the volume which may be reached in the traditional cycle.

A diagrammatic illustration of the above conditions is expressed on Figures 1 and 2, representing respectively by a continuous line the theoretical Otto and Diesel cycles.

In the following, the differences existing between the respective actual cycles, as they occur in the engine, and the ideal cycles which are here given for the sake of simplicity, are omitted from consideration.

As known, the theoretic Otto cycle (Figure 1) comprises an adiabatic compression DA, a combustion at a constant volume AB, and an adiabatic expansion BC. At point C, in a conventional engine, it may be considered that the discharge at a constant volume begins, due to the opening of the respective valve and the simultaneous reascending of the piston to the top dead center. According to the invention, since during the "economical rate" at the opening of the valve at C, the gas, instead of being sent to exhaust, is repelled in the expansion cylinders (which are two in the particular embodiment) it may be affirmed with a good approximation that the cycle continues in fact according to the lines C, C', E, F, D, thus exploitig the larger expansion work equal to the hatched area C', E, F, D.

The C C' section is due to some lowering of the pressure for the volume of the auxiliary duct which will be described below. Therefore the result is greater useful work.

Furthermore, since in the "economical rate" the real combustion begins in only two cylinders, these may work, even when the total power delivered by the engine is not high, in conditions of unitary power approaching maximum power, and therefore with an efficiency approaching the maximum. Thus, all the advantages of the previously known methods are obtained while minimizing the respective drawbacks.

The same considerations apply to the Diesel cycle (Figure 2) wherein the adiabatic expansion BC is by means of the invention prolonged to the point E, gaining as useful work the hatched area C', E, F, D.

Figure 3 represents schematically a conventional 4-stroke, four cylinder, Otto cycle engine modified according to the invention to provide the above specified conditions.

Figure 3 shows the cylinder block 18 of a conventional 4-cylinder, 4-stroke internal combustion engine, the engine cylinders 1,2,3 and 4, the discharge ducts 5,6,7 and 8 of the cylinders 1 to 4, the intake valves 9, 10, 11 and 12 of the four cylinders, the discharge valves 13,14, 15 and 16 of the four cylinders, and the body 20 of a device to be applied to the engine and in which is housed an auxiliary duct 21 connecting the exhaust manifolds of the four cylinders. The duct 21 may be located very nearthe discharges of the cylinders 1,2,3,4, resulting in a much reduced volume, thereby allowing a remarkable reduction of the dead spaces. Mobile sluice valves 22 and 23 are pivoted on points 24 and 25, located at the ends of duct 21.

The sluice valves 22 and 23 may be rotated around the respective pivots 24 and 25 and firmly oriented both in the respective positions 22' and 23' for the engine to operate at the "normal rate", and in the positions 22" and 23" to obtain the operation of the engine at the so-called "economical rate".

Rotating valves 26, 27 are located, as indicated in Figures 3 and 3a, at the intersections of the duct 21 with the discharge ducts 6 and 7 of the cylinders 2 and 3. The valves 26 and 27 may for example have a cylindrical shape with the axis perpendicular to the plane of Figure 3, and be rotatable around this axis and provided with holes 28 and 29 respectively perpendicular to their axis. They may alternatively have any other suitable shape (e.g. they may be appropriately actuated head valves). The valves 26 and 27 are rotated at a speed which is half the rotational speed of the engine crankshaft and there fore equal to that of the camshaft or camshafts.

However constructed, these valves must open and close once at each revolution of the engine crank shaft. The phasing of the valves 26 and 27 must be such as to allow, through their holes 28 and 29, the outlet of the discharge gases through the respective ducts 6 and 7 when the exhaust valves 14and 15 are open, in the engine normal cycle.

When the "normal rate" of the engine operation is desired, the following conditions operate: - the intake valves 9, 10, 11 and 12 are regularly actuated by the respective camshaft according to the motion and the phasing provided for the normal condition operation of the engine; - the exhaust valves 13, 14, 15 and 16 are similarly actuated by the respective camshaft according to the motion and the phasing provided for the normal operation; - the sluice valves 22 and 23 are oriented by rotating them around the respective pivots 24 and 25 to the stable position 22' and 23' so that the fluids discharged by the cylinders 1 and 4 are deviated in the respective discharge ducts 5 and 8;; - the rotating valves 26 and 27 may rotate according to the above stated modes and phasing (that is, in such a way as to allow, when the cylinders 2 and 3 are in the exhaust phase, the passage of gas through their respective discharge ducts 6 and 7) or may be locked in the position indicated in Figure 3.

Under these conditions, the engine operates in the normal way and the discharge gases are regularly expelled through the respective ducts 5, 6,7 and 8.

To obtain the so-called "economical rate" operation of the engine it is sufficient to: - rotate the sluice valves 22 and 23 around the respective pivots 24 and 25 to bring them to the respective positions 22" and 23", whereupon the discharge gases of the cylinders 1 and 4 are deviated through the duct 21 instead of passing through the respective exhaust ducts 5 and 8; and - rotate the valves 26 and 27 (if previously, in the normal operation, they had been locked in the position indicated in Figure 3) at a speed equal to half the speed of the crankshaft and therefore equal to that of the camshaft or camshafts.

The phasing of the valves 26 and 27 must be such that the holes 28 and 29, formed perpendicular to the rotational axes of the valves, are in the position indicated in Figure 3 in both the cases wherein, in the "normal rate", the dischargevalves 14 and 15 would be respectively open while the two pistons of the cylinders 2 and 3 are ascending towards the top dead center in the exhaust phase. This is intended to permit in this period the outlet of the discharge gases from the cylinders 2 and 3 through the holes 28 and 29. The intake valves 9 and 12 of the respective cylinders 1 and 4 must be actuated by the respective camshaft according to the same motion and phasing provided for the normal operation of the engine, while the intake valves 10 and 11 of the respective cylinders 2 and 3 must be disengaged from the motion of the camshaft and kept constantly closed, by means of an appropriate known device, or the intake ducts of the cylinders 2 and 3 must be closed.

The discharge valves 13 and 16 ofthe cylinders 1 and 4 are actuated by the respective camshaft according to the motion and phasing provided for the engine normal operation, while the discharge valves 14 and 15 of the cylinders 2 and 3 must be disengaged from the camshaft motion and kept constantly open, by means of an appropriate known device.

In the so-called "economical rate" operation the cylinders 1 and 4 operate regularly as propulsor cylinders, exactly in the same way as in the case of the "normal rate" operation. Similarly, the intake valves 9 and 12 and the discharge valves 13 and 16 of the cylinders 1 and 4 operate completely in the conventional manner.

The cylinders 2 and 3 are utilized to prolong the expansion of the combustion gases before their discharge into the ambient atmosphere.

The operation of the engine in the so-called "economical rate" will be now described.

When the cylinder 1 (at the end of the thermal cycle occurring during the normal conditions) initiates the discharge phase by the reascending of the piston from the bottom dead center towards the top dead center and the opening of the discharge valve 13, the discharge gases are deviated by the sluice valve 22 which is in the position 22" into the auxiliary duct 21. The gases meet therein with the rotating valves 26 and 27 both so oriented that the holes 28 and 29 are in a position perpendicular to the respective positions indicated in Figure 3 and therefore the passage to the discharge ducts 6 and 7 is closed. Therefore, the discharge gases cannot pass out through the ducts 6 and 7 nor through the duct 8 because the sluice valve 23 is in the position 23".

Similarly, the discharge gases of the cylinder 1 cannot enter the cylinder 4, because the latter is in the compression phase and its discharge valve 16 is then closed. The discharge gases meet with the discharge valves 14 and 15 which are open (permanently) and they can then pass into the cylinders 2 and 3 and expand, facilitating the simultaneous descent of their pistons, since the thrust surface on these pistons is double that on the piston of the cylinder 1 expelling the gases (the intake valves 10 and 11 being permanently closed).

The discharge gases of the cylinder 1 can therefore complete their expansion in the cylinders 2 and 3 until the pistons within these cylinders have not completed their descent towards the bottom dead center. At the end of the expansion the useful volume is therefore double with respect to the initial volume in the cylinder 1. When the pistons of the cylinders 2 and 3 begin jointly the reascending motion towards the top dead center, the discharge gases are passed again through the valves 14 and 15 (which are permanently open while the valves 10 and 11 are permanently closed) into the auxiliary duct 21.Passage of the discharge gases towards the cylinder 1 (the discharge valve 13, in the meantime, having been closed), towards the cylinder 4 (the discharge valve 16 being still closed because the cylinder 4 is in the expansion phase), and towards the discharge ducts 5 and 8 (the sluice valves 22 and 23 being in the respective positions 22" and 23") is prevented, and the gases pass through the holes 28 and 29 of the rotating valves 26 and 27 (which in the meantime have been rotated through 90 and are located as shown in Figure 3) towards the discharge manifolds 6 and 7 to the outside.

The force of the discharge gases produced within the cylinder 4 is exactly identical to that occurring in the cylinder 1. Upon the opening of the discharge valve 16, passage of the discharge gases of the cylinder 4 towards the manifolds 5,6,7 and 8 as well as the passage towards the cylinder 1 is prevented, and the gases pass through the valves 14 and 15 into the cylinders 2 and 3 completing their expansion.

When the pistons of the cylinders 2 and 3 begin their reascent, the gases are again pushed into the auxiliary duct 21 through the valves 14 and 15 and they pass through the holes 28 and 29 of the valves 26 and 27, and through the manifolds 6 and 7 to the outside.

In one particular example, the fluid motion is therefore obtained, in the "normal rate", through the intake valves 9, 10, 11, and 12 and the discharge valves 13, 14, 15 and 16 and the respective discharge ducts 5,6,7 and 8. In the "economical rate" the input of the fluid is instead obtained only through the intake valves 9 and 12 while the outgoing gases pass through the valves 13 and 16 (with a normal unidirectional flow) and successively through the auxiliary duct 21 and pass into the cylinders 2 and 3 through the valves 14 and 15 and successively out through the same valves, passing again through the auxiliary duct 21, the holes 28 and 29 of the valves 26 and 27, and out through the discharge ducts 6 and 7.

In the "economical rate" operation the discharge valves 14 and 15 of the cylinders 2 and 3 are traversed in the two directions by the expanding fluid and are therefore utilized differently than in the conventional way.

It is thus clear that the auxiliary duct 21 should be as near as possible to the discharge valves 13,14,15 and 16 and must have the smallest possible volume compatible with the need to provide the best conditions for the motion of the discharge gases.

As will be apparent from the preceding description, the engine is operable as follows: - the utilization of the engine in the "normal rate" operation; - the transition (manual or automatic), in the case of low power delivery, from the normal rate operation to the economical rate. In this case: - the cylinders 1 and 4 are utilized in the conventional way, but being utilized to deliver power values very near to the maximum specific power; - the cylinders 2 and 3 are utilized to increase the useful work of the fluid which enters and goes out from them only through the discharge valves 14 and 15, thereby compensating for the friction power loss and making the temperature distribution and the wear of the cylinders uniform; - due to the prolonged expansion, the percentage of the unburnt gases is reduced.

In other words, during the "economical rate" operation the specific power required for the cylinders 1 and 4 is doubled because the two cylinders deliver the same power which would be delivered by the four cylinders in the normal rate; this means that the two active cylinders work in optimum efficiency conditions when the power required is equal to half the maximum power. Further, the engine operation is in greater equilibrium since the two expansion phases, which are out of phase by 180 with respect to the preceding, add to the two active phases (one at each 360 rotation of the crankshaft). Furthermore, no substantial modifications to a normal internal combustion engine is required.

Still referring to Figure 3 and 3a, the actuating means for the rotating valves 26 and 27 may be suitably a shaft 30 which may take the motion from for example one of the camshafts or from another member of the engine rotating at the same speed (these elements are not indicated in the drawing) and transmit the motion to the rotating valves 26 and 27 through pairs of bevel gears 31 and 32.

Figure 4 shows the shaft 30 transmitting the motion through the bevel gear pair 31 and 32 to the rotating valve 26, upper and lower pivots 33 and 34 for the rotation of the valve, the duct 21 and the discharge valve 14 of the cylinder 2.

Figure 5 is a side view from the discharge side. To provide the "economical rate" operation it is necessary for the intake valves 10 and 11 of the cylinders 2 and 3 to remain permanently closed or to close the intake ducts of the same cylinders. This is easily achieved through the use of known means.

The same consideration is valid for the means which are required to keep the discharge valves 14 and 15 of the cylinders 2 and 3 permanently open during the "economical rate" operation of the engine.

As will be apparent from the above description, the present invention can be applied to reciprocating internal combustion engines of conventional type without any substantial alteration of the design thereof.

Further, the invention permits the maximum possible useful expansion of the gases in a 4-cylinder engine, due to the dead space being reduced to a minimum and the descent stroke of the pistons within the inactive cylinders being completely utilized to produce useful work. Furthermore, the temperature and the wear of the engine cylinders are as uniform as possible.

By the increase of the expansion duration during the combustion, beneficial effects are further obtained with respect to the presence of unburnt gases.

Claims

1. An Otto or Diesel cycle internal combustion engine, comprising at least four cylinders each having an intake valve, a discharge valve, and a discharge duct, an auxiliary duct connecting the exhausts of the cylinders, valves located in the exhausts of two of the cylinders so as to allow exhaust gas therefrom to pass either through the respective discharge duct or into the auxiliary duct, and rotatable valves located in the exhausts of two other cylinders, the engine being operable normally wherein the exhaust from each of the cylinders passes through the respective discharge duct or in an alternative manner wherein the intake valves and the discharge valves of the said two other cylinders are fixed to be closed and open respectively, the valves located in the exhausts of the first-mentioned cylinders are arranged to pass exhaust gas therefrom into the auxiliary duct, and the valves located in the exhausts of the said two other cylinders are rotated, whereby exhaust gas from a first-mentioned cylinder passes into the auxiliary duct, into and out of the said other cylinders while the rotatable valves are closed, and then through the discharge ducts of the said other cylinders when the rotatable valves are open.

2. An engine as claimed in Claim 1, wherein at least one pair of said rotatable valves are arranged to effect in phase the opening and the closing of the passage of exhaust gas towards the discharge ducts of the said two other cylinders at each complete revolution of the engine crankshaft.

3. An engine as claimed in Claim 1 or 2, wherein the said valves located in the exhausts of the two first-mentioned cylinders are sluice valves.

4. An engine as claimed in any of Claims 1 to 3, wherein the transition between the normal operation thereof and the said alternative operation thereof may be selected by the driver or by a small automatic control exchange which processes the running parameters.

5. An engine as claimed in any of Claims 1 to 4, which is a 6 cylinder Otto or Diesel cycle engine, in which the cylinders wherein the normal combustion initiates in the normal operation are two and dephased, in the active cycle, by 360 while the cylinders utilized for the mixture expansion are four.

6. An engine according to Claim 1, substantially as herein described with reference to, and as shown in, Figures 3 to 5 of the accompanying drawings.

7. A device to be applied to an Otto or Diesel cycle internal combustion engine so as to become an integral part of the engine for the utilization of the engine either, in the known normal operating rate, wherein in all the cylinders occurs the beginning of the gas combustion, or in a particular operation rate defined as an economical rate according to which the combustion does not begin in all the cylinders of the engine but in only one or more of them, while at least two or more cylinders are utilized to complete the expansion begun in the cylinder or cylinders wherein the combustion initiates, the device comprising a duct wherein through mobile sluice valves which may be oriented in stable positions to obtain the economical operation, the discharge gases coming from the discharge valves of cylinders wherein the normal combustion cycle initiates and takes place, are collected, the device further comprising at least one valve rotating at a speed equal to half the speed of the crankshaft, the said valve being provided with a hole to allow the discharge in phase of the gases into the exhaust ducts as well as, alternately and in phase, the interception of the said discharge, means for locking the intake valves of the inactive cylinders in the closed position and/or the closure of the intake ducts of the inactive cylinders, means for locking the discharge valves of the inactive cylinders in a permanently open position so that the discharge gases, coming alternately from the cylinders wherein the regular combustion initiates and takes place, while they go out through the respective discharge valves are deviated by the said sluice valves into the said duct and from there, meeting closed, in phase, by the rotating valves, the respective passages towards the discharge ducts, the said gases penetrate into the inactive cylinders through their discharge valves permanently open, expanding and producing active work until a volume nearly the double of that of the respective provenance cylinders and are subsequently pushed again by the simultaneous reascending motion of pistons of the inactive cylinders, still through the said discharge valves, in the duct from which they go out into the discharge ducts through the openings of the rotating valves which are in the phased discharge position, all in order to improve the overall efficiency of the engine and hence its specific consumption by the utilization of the active cylinders at the maximum of their specific power and improving the useful expansion of the gases when the engine is utilized at power delivery rates considerably lower than the maximum, and also to reduce the unburnt gases.