WO2017045667A1

WO2017045667A1 - Reciprocating piston engine with a variable compression ratio, and method for changing the compression ratio of a reciprocating piston engine

Info

Publication number: WO2017045667A1
Application number: PCT/DE2016/100422
Authority: WO
Inventors: Uwe Schaffrath; Mike Souren; Andre Prinz
Original assignee: Fev Gmbh
Priority date: 2015-09-16
Filing date: 2016-09-12
Publication date: 2017-03-23
Also published as: DE112016004197A5

Abstract

The reciprocating piston engine (10) is provided with a rotatably mounted crankshaft (26) which is arranged in a housing (12), and with at least one connecting rod (18) which is mounted rotatably on the crankshaft (26) by means of a crankshaft bearing (32) which has a lubricant path (33). The connecting rod (18) supports a compression piston (16) which is guided such that it can be moved bi-directionally in a cylinder (14) which is configured in the housing (12). Furthermore, the reciprocating piston engine has an adjusting mechanism for adjusting the compression piston (16) relative to the connecting rod (18) for the purpose of changing the compression ratio, wherein the adjusting mechanism has an adjusting element (38) for displacing the compression piston (16) relative to the connecting rod (18), and at least one cylinder/piston supporting unit (54, 56) with a supporting cylinder (58, 62), and a supporting piston (60, 64) which is guided displaceably in the said supporting cylinder (58, 62) and is operatively connected to the adjusting element (38). Furthermore, the operating space (70, 72) is connected fluidically via a feed duct (74, 76) to the lubricant path (33) of the crankshaft bearing of the connecting rod (18), wherein the connecting rod (18) has a discharge duct (78, 80) which extends from the at least one working space (70, 72) of the supporting cylinder (58, 62) and can be brought into a fluidic connection with an outlet opening which is arranged in the outer surface of the connecting rod (18) in order to discharge fluid from the at least one working space (70, 72) into the housing (12).

Description

Reciprocating piston engine with variable compression ratio and method for changing the compression ratio of a reciprocating engine

The invention relates to a reciprocating engine with variable compression ratio, wherein it is in particular a reciprocating internal combustion engine in the reciprocating piston engine. Furthermore, the invention relates to a method for changing the compression ratio of a reciprocating piston engine, in particular a reciprocating internal combustion engine.

Reciprocating engines and in particular reciprocating internal combustion engines with variable compression ratio are known in principle. Their advantages are to be seen in particular in an increased efficiency.

In order to change the compression ratio, reciprocating internal combustion engines with a variable compression ratio have at least one engine component whose geometry or position is variable in order to adjust the compression ratio. The adjustment of said engine component can be done electrically or magnetically. As appropriate, a hydraulic adjustment of the engine component has been found to be used as hydraulic fluid, the engine oil, as it is used for lubrication and cooling of the reciprocating engine.

With regard to the adjustment of the engine component, it is advantageous if forces acting on the engine component during operation of the reciprocating piston engine are used for this purpose. For then it does not require a separate actuator for adjusting the engine component.

As an engine component that is changeable to adjust the compression ratio, in particular the connecting rod with compression piston as proved appropriate. By relative displacement of compression piston and connecting rod, the effective connecting rod length and thus the compression ratio can be changed. During operation of the reciprocating piston engine, so-called gas and mass forces act on the compression piston. The gas forces arise during the expansion of the gas-fuel mixture. These forces press the compression piston against the connecting rod. With eccentric mounting of the compression piston relative to the longitudinal axis of the connecting rod can be achieved that these gas forces move the compression piston in the direction of the connecting rod. In this way the compression ratio can be changed from high values to low values. If this is not desired, namely because the reciprocating engine is to be operated at a high compression ratio, the adjusting element is locked for the compression piston, which is done for example by a cylinder / piston support unit.

Conversely, using the mass forces, the compression ratio can be changed from low to high values. Here, the accelerations are used, which act on the compression piston when it passes through its top dead center. A movement of the compression piston in these phases can in turn be prevented by a cylinder / piston support unit which acts on the adjusting element for the compression piston. But it is also possible that one and the same cylinder / piston support unit is designed for both functions; such a support unit operates with a double-acting support piston.

As mentioned above, the support unit is operated hydraulically, preferably not actively, but passively by either hydraulic fluid is sucked into the working space or from the working space as a result of induced by the forces described above displacement of the support piston within the support cylinder Support piston is displaced.

An example of a reciprocating engine with variable compression ratio (also called VCR) is described in WO 2014/019683 AI and WO 2014/019684 AI. As mentioned above, in the hydraulic adjustment of the compression ratio hydraulic fluid is displaced from the working space of a support cylinder, as a result of a displacement of the support piston, which in turn is the result of forces acting on the compression piston. In this case, the hydraulic fluid is "pumped", so to speak, whereby the flow resistance should be as low as possible.

The object of the invention is a reciprocating engine with variable compression ratio and a method for changing the compression ratio of such a reciprocating engine, in particular a reciprocating internal combustion engine proposed, which is provided with

a housing,

a rotatably mounted crankshaft arranged in the housing, at least one connecting rod, which is rotatably mounted on the crankshaft by means of a crankshaft bearing having a lubricant path, wherein the connecting rod carries a compression piston, which is bidirectionally movably guided in a cylinder formed in the housing, and an adjusting mechanism for adjusting the compression piston relative to the connecting rod for the purpose of changing the compression ratio, wherein the adjusting mechanism comprises an adjusting element for displacing the compression piston relative to the connecting rod and at least one cylinder / piston support unit with a support cylinder and a support piston guided displaceably in this, which in operative connection with the adjusting element stands,

wherein the support cylinder has at least one work space which can be filled with a substantially incompressible fluid, in particular oil, which can optionally be introduced into the work space or can be discharged from the work space, and

wherein the working space via an inlet channel in fluid communication with the lubricant path of the crankshaft bearing of the connecting rod.

This reciprocating engine is inventively characterized in that the connecting rod has a flow channel extending from the at least one working chamber of the support cylinder, which can be brought into fluid communication with a discharge opening arranged in the outer surface of the connecting rod for discharging fluid from the at least one working space into the housing.

The connecting rod comprises the actual Pleuelkörper and arranged on / in this parts, which define as the Pleuelkörper the outer surface of the connecting rod in the context of the invention.

Furthermore, to solve the problem, a connecting rod for a reciprocating engine with variable compression ratio, in particular for a reciprocating internal combustion engine, a housing, a housing disposed in the rotatably mounted crankshaft, at least one cylinder formed in the housing and a bidirectionally movable in the cylinder Compression piston, wherein the connecting rod is provided with

a connecting rod body with a crankshaft bearing for rotatably supporting the connecting rod body on the crankshaft, wherein the crankshaft bearing has a lubricant path,

a compression piston bearing for mounting a compression piston on the connecting rod body,

an adjusting mechanism for displacing the compacting piston bearing relative to the connecting rod body for changing the compression ratio of the reciprocating piston engine,

wherein the adjusting mechanism has an adjusting element for displacing the compacting piston bearing relative to the connecting rod body and at least one cylinder / piston supporting unit with a supporting cylinder and a support piston displaceably guided in this, which is in operative connection with the adjusting element,

wherein the working space via an inlet channel in fluid communication with the lubricant path of the crankshaft bearing of the connecting rod body is.

According to the invention, the connecting rod is characterized in that the connecting rod body has a flow channel extending from the at least one working space of the support cylinder, which can be brought into fluid communication with an outlet opening arranged in the outer surface of the connecting rod body for discharging fluid from the at least one working space into the housing ,

In addition to the structural part of the connecting rod, the connecting rod body also includes parts arranged in / on it, which, like the connecting rod body, define the outer surface thereof in the sense of the invention.

Finally, the above object is also achieved by a method for changing the compression ratio of a reciprocating engine, in particular a reciprocating internal combustion engine, with variable compression ratio as described above and / or with at least one connecting rod, also as described above, wherein the fluid from the at least one Working space of the at least one support cylinder for the purpose of changing the compression ratio is discharged directly into the housing of the reciprocating engine.

In this case, it is preferably provided that, in a displaced position of the support piston, which corresponds to one of at least two compression ratios, a fluid connection between the inlet and outlet channels assigned to the support cylinder is blocked by the support piston.

According to the invention, it is accordingly provided that the hydraulic fluid, which is removed during displacement of the support piston from the working space of the support cylinder, is discharged directly into the housing of the reciprocating engine. As a result, the flow resistance is as low as possible, since the drained hydraulic fluid no changeover valves or the like. must flow through the flow resistance increasing fluidic elements. According to the invention, as the "hydraulic fluid" pressed out of a support cylinder, in particular engine oil, is discharged freely into the oil sump of the reciprocating engine, while the engine oil to be supplied to the working space or into the working chamber of the support cylinder is completely removed from the oil circuit, and as a rule from the crankshaft connecting rod bearing. Alternatively, however, the oil can also be taken from another bearing, which is lubricated and cooled with the engine oil. If sufficient oil can be supplied from the respective bearing, thereby the adjustment of the compression piston is accomplished faster than in known systems, since the pressure difference for the dissipated oil while higher and the flow resistance is lower than when the oil is dissipate against the oil pressure, as in the known so far with "closed" hydraulic circuit operating systems is the case.

As described above, the working space of a support cylinder is associated with a supply channel and a discharge channel, both of which open into the working space of the support cylinder. The supply and removal of hydraulic fluid into and out of the working space should be carried out expediently only during the adjustment phases for changing the compression ratio. Since, however, the discharge channel can be brought into fluid communication with an outlet opening arranged on the outer surface of the connecting rod, which is provided according to the invention for adjusting the compression ratio, a fluid connection exists between the inlet and outlet channels via the working space of the support cylinder. In the inlet channel is the current hydraulic fluid pressure, for example, the current engine oil pressure. Hydraulic fluid thus flows into the working chamber of the support cylinder via the inlet channel in order to immediately discharge into the housing via its outlet channel. Since this is without benefit in particular with constant compression ratio and also brings the disadvantages of increased oil requirements, the requirement of a larger oil pump and increased engine friction, according to an advantageous embodiment of the invention provides that the support piston in a displacement position, the one of at least two adjustable compression ratios, the inlet channel blocked with respect to the flow channel. In this Sliding position, the support piston is preferably not supported against a hydraulic fluid in the working space of the support cylinder, but directly from the bottom of the working space. The support piston acts in this situation as a blocking or blocking element to interrupt the "light" fluid connection of inlet and outlet channel.

In an advantageous embodiment of the invention it is provided that the support piston of the at least one or each cylinder / piston support unit has a circumferential sealing element for sealing the working space of the support cylinder and that the circumferential sealing element in a displacement position corresponding to one of at least two adjustable compression ratios, the Blocked fluid communication between the inlet and outlet channel in the working space of the support cylinder, and in particular closes the mouth of the inlet and / or the discharge channel in the working space of the support cylinder.

According to a further embodiment of the invention, it is expedient if the support piston has at least one or each cylinder / piston support unit at its the bottom of the working space of the support cylinder end facing a sealing element, wherein the inlet and / or outlet channel on the ground and / or at the side wall of the support cylinder open into the working space and wherein the sealing element in a displacement position corresponding to one of at least two adjustable compression ratios, the fluid communication between inlet and outlet channel blocked in the working space of the support cylinder, in particular the mouth of the inlet and / or the drainage channel closes in the working space of the support cylinder.

In a further advantageous embodiment of the invention can be provided that the sealing element is annular and in particular an O-ring and / or that the sealing element is a lamellar sealing element or operates in the manner of a lamellar seal and / or that the sealing element is plate-shaped. Finally, it is also conceivable and advantageous if the sealing element works in the manner of a labyrinth seal and that either a depression is formed in the support piston, in which in the said displacement position of the support piston immersed by the support cylinder in the working space protruding projection, or in the support cylinder, a recess is formed, in which in the said displacement position of the support piston, a projecting from the support piston into the working space projection is immersed. There may also be several pairs of such recesses and projections.

Further advantageous embodiments of the invention are the subject of the dependent claims.

The invention will be described below with reference to several embodiments and with reference to the drawings. In detail, they show:

FIGS. 1 to 12

the individual phases of the relative displacement of the compression piston relative to the connecting rod using a first embodiment of a changeover valve according to a first embodiment for releasing or blocking the supply and discharge of hydraulic oil from or into the working spaces of two cylinder piston support units, as required;

FIGS. 13 to 24

the individual phases of the relative displacement of the compression piston relative to the connecting rod using a first embodiment of a switching valve according to a second embodiment for releasing or blocking or blocking the inflow and outflow of hydraulic oil from or into the working spaces of two cylinder piston support units and FIGS. 25 to 28

four variants of blocking a fluid connection between inlet and outlet channel in at least one cylinder / piston support unit, as according to the embodiments of FIGS. 1 to 12 or 13 to 24 can be used.

With reference to FIG. 1, the essential components of a reciprocating internal combustion engine 10 will briefly be discussed below, in which the compression ratio is variable, in two stages, it being noted that the invention is not limited to the number of adjustable compression ratios.

The internal combustion engine 10 has a housing 12, in which at least one cylinder 14 is formed. In the cylinder 14, a compression piston 16, which is mounted on a connecting rod 18 moves. Above the compression piston 16 is the combustion chamber 20, into which an inlet channel and an outlet channel 24 open. The ignition device for the air-fuel mixture is shown in FIGS. not shown.

The connecting rod 18 is moved in a known manner by a crankshaft 26. This crankshaft 26 has counterweights 28 with crank pins 30, on which the individual connecting rods 18 are mounted. The Kurbelwellenpleuellager 32 is acted upon in a known manner with pressurized engine oil and has a lubricant path 33. The corresponding lubricant system has a pump 34, which sucks engine oil from the oil sump 36 of the housing 12. In addition to lubrication, the engine oil also serves to cool, for example, the bearings of the internal combustion engine 10.

1, at the upper end of the connecting rod 18 there is a (for example eccentric) adjusting element 38 in the form of an adjusting lever 39, which is pivotably mounted on the connecting rod 18. Eccentrically to the pivot point 40 of the adjusting element 38, the pin 42 is mounted, which carries the compression piston 16. The center of the pin 42 is shown at 44. By pivoting the adjusting element 38 so the compression piston 16 moves relative to the connecting rod 18th

The adjusting lever 39 has a first end 46 and a remote from this second end 48, on each of which piston rods 50, 52 are articulated. The piston rods 50, 52 are part of two cylinder / piston support units 54, 56, of which the first support unit 54 has a first support cylinder 58 formed in the connecting rod 18 with a displaceably guided in this first support piston 60, while the second support unit 56 has a second support cylinder 62 having guided in this second support piston 64. These two support units 54, 56 serve to lock the adjusting element 38 in its two Maximalverschwenkpositionen, in each of which another of the two support piston 60, 64 abuts the bottom 66 and 68 of the respective support cylinder 58 and 62 respectively.

Between the support piston and the bottom of the associated support cylinder of each support unit 54, 56, the working space 70 and 72, respectively, flows into or out of the hydraulic fluid when the compression ratio is adjusted. For this purpose, an inlet channel 74 or 76 and an outlet channel 78 or 80 open into each of the two working chambers 70, 72. Via a hydraulic circuit with, for example, throttles or orifices 82, 84, check valves 86, 88 and a changeover valve 90, the two working chambers 70, 72 interconnected, so that the desired adjustment of the compression ratio can be made from a high to a low value or vice versa , The hydraulic circuit is via the channel 92 with the connecting rod bearing 32 and thus with the

Lubricant path 33 of the connecting rod bearing 32 is connected. Thus, the hydraulic circuit is ultimately supplied with engine oil.

The switching valve 90 is a 2/3-way valve, ie a valve that can assume two switching positions and has three connections. The three connections are in the two switch positions in different Licher manner interconnected or blocked with each other. The actuation of the switching valve 90, for example, mechanically, electrically, magnetically or hydraulically, and indeed whenever the compression ratio is to be changed from one value to the other value. The constructive solution for adjusting the switching valve 90 is not the subject of the invention and will therefore not be further described here. Examples of related constructions are described in WO 2014/019683 AI and WO 2014/019684 AI.

In the Fign. 1 to 6, the switching valve 90 is in the position in which the compression ratio can be changed from a high to a low value. The starting point is Fig. 1; the compression ratio is maximum in this case, which means that the compression piston 16 has its greatest possible distance from the connecting rod 18. The second support piston 64 abuts the bottom 68 of the second support cylinder 62, while the support piston 60 is supported in the support cylinder 58 on an oil pad, since the working space 70 of the support cylinder 58 is filled with engine oil.

In the first switching position of the switching valve 90 according to FIGS. 1 to 6, engine oil may be forced out of the working space 70 thereof as a result of displacement of the first support piston 60 into the first support cylinder 58, as a result of displacement of the first support piston 60, the second support piston 64 moves away from the bottom 68 of the second support cylinder 62 and thus Engine oil is sucked into the second support cylinder. A reverse engine oil flow is excluded by the hydraulic circuit and as a result of taking the first position of the switching valve 90.

Fig. 1 shows the situation immediately prior to ignition of the compressed air in the combustion chamber 20 air-fuel mixture. As a result of the ignition, gas forces act on the compression piston 16, which lead to a rotation of the adjusting element 38 in the direction of the arrow 96 when the discharge channel 78 is released. As a result, when the compression piston 16 has reached its bottom dead center (see FIG. 2), the first support piston 60 is already further in the first Workspace 70 of the first support cylinder 58 immersed, while the second support piston 64 has moved away from the bottom 68 of the second support cylinder 62 while hydraulic fluid passes into its working space 72. FIG. 3 shows the situation when compression piston 16 returns to its top dead center at the end of the exhaust stroke, from which point it returns to its bottom dead center during the intake stroke, as shown in FIG. In this phase, no gas forces acting on the compression piston, which could move this relative to the connecting rod 18. At most, at or shortly after passing through the bottom dead center (FIG. 2), mass forces acting on the compression piston 16 may act on the compression piston 16 against the connecting rod 18.

However, these gas forces act again at the next ignition of the air-fuel mixture, as shown in Fig. 5. As a result thereof, the adjusting element 38 again pivots in the direction of the arrow 96, it being assumed here that, after the action of gas forces on the compression piston twice, it assumes its position closest to the connecting rod 18. In this position, the first support piston 60 has moved against the bottom 66 of the first support cylinder 58, while the second support piston 64 has assumed its position at a maximum distance from the bottom 68 of the second support cylinder 62. The entire second working space 72 of the second support cylinder 62 is filled with engine oil. As a result, acting gas forces do not further adjust the compression piston 16.

In FIGS. 7 to 12, individual phases of two successive operating cycles of the internal combustion engine 10 are shown, which are used to increase the compression ratio from the low value set according to FIG. 6 to the high value according to FIG. 12 or FIG adjust. The switching valve 90 assumes its second position, in the engine oil from the second working space 72 can be discharged, while engine oil in the first working space 70 is introduced einaugbar. The removal of engine oil from the second working space 72 takes place as a result of the (further) in the second support cylinder 62 advancing second support piston 64, which means that at the same time the first support piston 60 moves away from the bottom 66 of the first support cylinder 58 and sucks engine oil, so to speak. In the second position of the change-over valve 90, only this direction of engine oil transfer is possible; Backflow of engine oil is excluded by the hydraulic circuit.

Starting point is the situation shown in FIG. 7. After ignition of the air-fuel mixture of the compression piston 16 reaches its bottom dead center. Due to the accelerations acting on the compression piston 16 when passing through the bottom dead center, a force acting on the compression piston 16 force that pushes the piston 16 down while the connecting rod 18 is already moving upwards. A relative displacement of compression piston 16 and connecting rod 18 and thus a "compression" of the effective length of the connecting rod 18 is not possible because the first support piston 60 rests on the bottom 66 of the first support cylinder 58. When the next top dead center of FIG. 8 is reached, mass forces acting on the compression piston 16, which pull on the compression piston 16 ", when the connecting rod 18 moves down again after passing through top dead center 10), wherein it is also assumed here that the final displacement of the compression piston 16 relative to the connecting rod 18 is already reached after two working cycles, as shown in Fig. 12. In the situation according to Figs 11 shifts when driving through the bottom dead center of the connecting rod 18 of the compression piston 16, act against the oppressive inertial forces relative to the connecting rod 18, since this is prevented by blocking the backflow of engine oil within the hydraulic circuit.

It should be noted at this point that in both variants of the system according to FIGS. 1 to 12 and 13 to 24 can also use a changeover valve, which in a third changeover position prevents the outflow (and possibly also the inflow) of engine oil into and out of working spaces. Thus, the adjusting element 38 could be in an intermediate position between the End positions according to Figs. 1 and 6 or Fign. 13 and 19 remain. Both support pistons would thus each be supported on a motor oil pad.

As already mentioned above, the adjusting forces resulting from the inertial forces, in particular at low rotational speeds of the internal combustion engine, are significantly lower than the adjusting forces resulting from the gas forces. The adjustment of the compression ratio from a small value to a large value is thus much more critical than the adjustment of a large compression ratio to a small compression ratio. In order to take this circumstance into account, according to the invention, the engine oil forced out of the second support cylinder 62 when adjusting from small to large compression ratio is discharged directly into the housing 12 of the internal combustion engine 10 and thus into the oil sump 36. This is shown in FIGS. 7 to 12 shown. In the embodiment according to FIGS. 1 to 12, this procedure also applies to the case where engine oil is forced out of the working space 70 of the first support cylinder 58 when the first support piston 60 moves further into the first support cylinder 58 (see Figs. With this adjustment of the compression ratio from high to low value, however, such a measure would not be absolutely necessary since, as mentioned above, the gas forces are sufficiently large. The measure described above is therefore particularly helpful in utilizing the mass forces to change the compression ratio, which is required primarily for the adjustment of the compression ratio from a small value to a large value.

By discharging the engine oil from the second support cylinder 62 directly into the housing 12 of the internal combustion engine, the flow resistance experienced by the pressed out engine oil is significantly lower than in the cases in which the drained engine oil is directly coupled into the hydraulic circuit again.

As already mentioned above, this measure does not necessarily require the case in which the engine oil from the first working space 70 of the first supporting cylinder 58 is pushed out. In the Fign. 13 to 24 is therefore a variant of the hydraulic circuit with respect to FIGS. 1 to 12 alternatively ausgestaltetem switching valve 90 'shown. The switching valve 90 'is designed as a 2/4-way valve, it being possible to discharge engine oil directly into the housing via one of the valve connections, while it is fed directly to the hydraulic circuit via another connection. The situations according to FIGS. 13 to 18 corresponds to those in FIGS. 1 to 6 shown situations. Here, in turn, it is shown how the adjustment of the compression piston 16 in the direction of the connecting rod 18, so a "Pleuelstauchung" takes place. The displaced from the first working chamber 70 engine oil passes back directly into the hydraulic circuit. In contrast, the switching position of the switching valve 90 'according to FIGS. 19 to 24 such that from the working space 72 of the second support cylinder 62 displaced engine oil is discharged directly into the housing of the internal combustion engine 10 and thus in the sump 36.

A certain problem with the discharge of engine oil displaced from the relevant support cylinder during the adjustment of the compression ratio directly into the housing of the internal combustion engine is that it requires a fluid connection between inlet channel and outlet channel via the working space of the respective support cylinder. As long as the adjustment of the compression ratio has not been completed, this "short circuit" is desired for the reasons mentioned above. However, when the compression piston 16 has moved relative to the connecting rod 18 to one of the two end positions, the internal combustion engine thus operates at the desired set compression ratio, it is expedient if this short circuit no longer exists. For this purpose, with reference to FIGS. 25 to 28 referred to several embodiments, wherein the support piston in the respective support cylinder for blocking the fluid connection of inlet channel and outlet channel provides. This will be explained below using the example of the second cylinder / piston support unit 56, wherein in FIGS. 25 to 28 a part of the hydraulic circuit of Figs. 1 to 24 and in particular the selectively selectively in fluid communication with the outlet channel 80 can be brought outlet opening 97 which is located in the outer side 98 of the connecting rod 18 and over the engine oil of the hydraulic circuit is discharged directly into the housing 12 of the reciprocating internal combustion engine 10.

According to FIG. 25, the second support piston 64 has a piston ring in the form of a peripheral sealing element 100, via which the second working space 72 in the second support cylinder 62 is sealed. Until the end position of the support piston 64, in which this rests against the bottom wall 68 of the second support cylinder 62, the fluid connection between the inlet channel 76 and the outlet channel 80 is maintained. When at the bottom 68 of the first support cylinder 62 adjacent second support piston 64 now closes the peripheral sealing element 100, the mouth opening 102 of the drain passage 80. The situation could also be realized vice versa, namely the mouth opening 104 of the inlet channel 76 is closed by the circumferential sealing element 100 ,

FIG. 26 shows an embodiment for the obstruction of the fluid connection between the inlet channel 76 and the outlet channel 80 in the form of a labyrinth seal 105. In this case, an annular recess 108 is incorporated in the end face 106 of the second supporting piston 64 facing the bottom 68 of the second supporting cylinder 62 in which a protruding from the bottom 68 annular projection 110 is immersed when the second support piston 64 rests against the bottom 68 of the second support cylinder 62. Instead of an annular recess 108 in the second support piston 64, a plurality of preferably concentrically arranged annular recesses 108 may be provided, in which case a plurality of preferably concentric, annular projections 110 also project from the bottom 68 of the second support cylinder 62. By this labyrinth seal the fluid connection between inlet channel 76 and outlet channel 80 is blocked.

In the previously described embodiment according to FIG. 26, the depression 108 in the second support piston 64 and the projection 110 at the bottom of the second support cylinder 62 are formed. It should be mentioned at this point that the situation is also possible the other way round or that with several recesses and projections these alternately in the second support cylinder 62 and in the second th support piston 64 may be arranged. It is crucial that through the interaction of recess and projection, there is a constriction and extension of the fluid connection between inlet channel 76 and outlet channel 80, whereby the desired sealing effect is achieved.

In the Fign. 27 and 28 embodiments are shown in which in the end face 106 of the second support piston 64, a sealing element 112 and 114 are arranged, which obstruct either the mouth opening 104 of the inlet channel 76 or the mouth opening 102 of the drain channel 80 on all sides. In the embodiment according to FIG. 27, the sealing element is an O-ring, while the sealing element 114 of the exemplary embodiment according to FIG. 28 is a plate, disk, block, strip or the like. is trained. While according to FIG. 28 the sealing element 114 closes the inlet opening 104 or 102 (depending on the embodiment), in the embodiment according to FIG. 27 the corresponding opening remains unlocked, whereby, however, the fluid connection to the respective other opening is obstructed by the sealing element 112.

The invention has been described above with reference to a VCR reciprocating engine in which the effective length of the connecting rod is changed to adjust the compression ratio. It should be emphasized at this point that the invention is not limited to such VCR reciprocating engines. Rather, the invention is generally applicable to the hydraulic adjustment of an engine component utilizing the forces acting on the engine component during operation. It is also possible that the adjustment of the compression ratio is supported by variation of the oil pressure.

According to the invention, the compression ratio can be actively or passively set for all cylinders of the internal combustion engine, for all cylinders of a cylinder bank of the internal combustion engine and / or for the individual cylinders of the internal combustion engine. In this case, preference is given to the geometry of an engine component such as, for example, the connecting rod length, the Crankshaft radius, the bearing of the crankshaft and / or the storage of the compression piston on the connecting rod and thus changed the effective connecting rod length. This is preferably done hydraulically, ie using a medium. Here, the motor oil is especially suitable as a medium. The active adjustment means that an adjustment of the relevant engine component is achieved by the action of external adjusting forces on the adjusting mechanism. The passive adjustment means that acting on the engine component during operation of the internal combustion engine forces such as the gas pressure forces and the inertial forces are utilized to effect an adjustment of the engine component. In the case of passive adjustment, therefore, due to the utilization of these forces, an automatic adjustment of the engine component takes place, while in the active adjustment from the outside, ie in addition to the aforementioned acting forces or independently thereof, further adjusting forces are introduced.

List of reciprocating piston internal combustion engine

casing

cylinder

compression piston

pleuel

combustion chamber

exhaust port

crankshaft

counterweights

crank pins

Kurbelwellenpleuellager

lubricant path

Engine oil pump

oil sump

adjustment

adjusting

Pivot point of the adjusting element / adjusting lever Bearing journal for the compression piston

first end of the adjusting element

second end of the adjusting element

piston rod

Cylinder / piston support unit

supporting cylinders

support piston

supporting cylinders

support piston

Floor, bottom wall of the support cylinder

Working space of the support cylinder 72 working space of the support cylinder

74 inlet channel to the working area

76 inlet channel to the working area

78 drainage channel from the working area

80 drainage channel from the work area

82 Iris of the hydraulic circuit

84 Iris of the hydraulic circuit

86 Check valve of the hydraulic circuit

88 Check valve of the hydraulic circuit

90 Changeover valve of the hydraulic circuit

90 'reversing valve of the hydraulic circuit

92 channel

94 arrow

96 arrow

97 outlet opening

98 outside of the connecting rod

100 circumferential sealing element

102 mouth of the drainage channel

104 mouth of the inlet channel

105 labyrinth seal

106 Front side of the support piston

108 deepening

110 advantage

112 sealing element

114 sealing element

Claims

1. Reciprocating engine with variable compression ratio, in particular reciprocating internal combustion engine, with

a housing (12),

one in the housing (12) arranged rotatably mounted crankshaft (26),

at least one connecting rod (18) which is rotatably mounted on the crankshaft (26) by means of a crankshaft bearing (32) having a lubricant path (33),

wherein the connecting rod (18) carries a compression piston (16) which is guided bidirectionally movable in a cylinder (14) formed in the housing (12), and

an adjustment mechanism for adjusting the compression piston (16) relative to the connecting rod (18) for the purpose of changing the compression ratio,

wherein the adjustment mechanism comprises an adjustment element (38) for displacing the compression piston (16) relative to the connecting rod (18) and at least one cylinder / piston support unit (54, 56) with a support cylinder (58, 62) and a support piston (35) displaceably guided in said support piston (16). 60, 64) which is in operative connection with the adjusting element (38),

wherein the support cylinder (58, 62) has at least one working space (70, 72) which can be filled with a substantially incompressible fluid, in particular oil, which can optionally be introduced into the working space (70, 72) or be discharged from the working space (70, 72) and wherein the working space (70, 72) via an inlet channel (74, 76) in fluid communication with the lubricant path (33) of the crankshaft bearing (32) of the connecting rod (18),

characterized ,

the connecting rod (18) has a drain extending from the at least one working space (70, 72) of the support cylinder (58, 62). Channel (78, 80), for the removal of fluid from the at least one working space (70, 72) in the housing (12) with a in the outer side (98) of the connecting rod (18) arranged in the outlet opening (97) in fluid communication is.

2. Reciprocating piston engine according to claim 1, characterized in that the support piston (60, 64) in a displacement position which corresponds to one of at least two adjustable compression ratios, the inlet channel (74, 76) opposite the flow channel (78, 80) blocked.

3. Hubkolbenmachine according to claim 2, characterized in that the support piston (60, 64) in the said displacement position against the bottom (66, 68) of the working space of the support cylinder (58, 62).

4. Reciprocating piston engine according to one of claims 1 to 3, characterized in that the adjusting element (38) of the adjusting a pivotable about a pivot point on the connecting rod (18) mounted adjusting element (38) having a first end (46) and a second end (48 ), wherein the adjusting element (38) between the fulcrum and its first end (46) has a bearing for supporting the compression piston (16) that the adjusting mechanism with a first cylinder / piston support unit (54) having a first support cylinder ( 58) having a with the first end (46) of the adjusting element (38) operatively connected to the first support piston (60), and with a second cylinder / piston support unit (56) is provided, which has a second support cylinder (62) having at the second end (48) of the adjusting element (38) operatively connected second support piston (64), and that at least the second support cylinder (62) in addition to an inlet channel (74, 76) and an Abl associated with channel (78, 80) which is in fluid communication with a in the outer surface of the connecting rod (18) arranged outlet opening.

Reciprocating piston engine according to claim 4, characterized in that the adjusting lever (38) is designed as an eccentric whose center forms the pivot point of the Versthebels (38) and eccentrically to its center, the bearing for the compression piston (16).

Reciprocating piston engine according to one of claims 1 to 5, characterized by a lubricant system with a pump (34) for supplying flowable lubricant, in particular oil, from the housing (12) to the crankshaft bearing (32) and / or to a compression piston bearing of the connecting rod (18). ,

Reciprocating piston engine according to one of claims 1 to 6, characterized in that the support piston (60, 64) of the at least one or each cylinder / piston support unit (54, 56) has a circumferential sealing element (100) for sealing the working space (70, 72) of the Supporting cylinder (58, 62) and that the circumferential sealing element (100) in a displacement position corresponding to one of at least two adjustable compression ratios in the working space (70, 72) of the support cylinder (58, 62), the fluid connection between inlet and outlet channel ( 74, 76, 78, 80), in particular the opening (104, 102) of the inlet or the discharge channel (74, 76, 78, 80) in the working space (70, 72) of the support cylinder (58, 62) closes.

Reciprocating piston engine according to one of claims 1 to 7, characterized in that the support piston (60, 64) at least one or each cylinder / piston support unit (54, 56) at its the bottom (66, 68) of the working space (70, 72) the support cylinder (58, 62) facing end face (106) has a sealing element (112, 114) that the inlet and / or outlet channel (74, 76, 78, 80) at the bottom (66, 68) of the support cylinder (58, 62) into the working space (70, 72) and that the sealing element (112, 114) in a displacement position corresponding to one of at least two adjustable compression ratios, in the working space (70, 72) of the support cylinder (58, 62) the fluid connection between intake and drain channel (74, 76, 78, 80) blocks, in particular the orifice (104, 102) of the inlet or the discharge channel (74, 76, 78, 80) in the working space (70, 72) of the support cylinder (58 , 62) closes.

9. Reciprocating piston engine according to claim 8, characterized in that the sealing element (112) is annular and in particular an O-ring and / or that the sealing element is a lamellar sealing element or operates in the manner of a lamellar seal and / or that the sealing element (114) plate- is shaped.

10. A reciprocating engine according to claim 8, characterized in that the sealing element in the manner of a labyrinth seal (105) works and that either in the support piston (60, 64) has a recess (108) is formed in the said displacement position of the support piston (60, 64) immersed in the working space (70, 72) protruding from the support cylinder (58, 62) projection (110) is immersed, or in the support cylinder (58, 62) is formed a recess in which in said sliding position of the support piston (60, 64) immersed by the support piston (60, 64) in the working space (70, 72) protruding projection is immersed.

11. connecting rod for a reciprocating engine with variable compression ratio, in particular for a reciprocating internal combustion engine,

a housing (12), a rotatably mounted crankshaft (26) arranged in the housing (12), at least one cylinder (14) formed in the housing (12) and a compression piston (16) bidirectionally movable in the cylinder (14) having,

wherein the connecting rod (18) is provided with

a connecting rod body with a crankshaft bearing (32) for rotatably supporting the connecting rod body on the crankshaft (26), the crankshaft bearing (32) having a lubricant path (33), a compression piston bearing for supporting a compression piston (16) on the connecting rod body, an adjusting mechanism for displacing the compacting piston bearing relative to the connecting rod body for changing the compression ratio of the reciprocating piston engine,

wherein the adjusting mechanism has an adjusting element (38) for displacing the compacting piston bearing relative to the connecting rod body and at least one cylinder / piston support unit (54, 56) having a support cylinder (58, 62) and a support piston (60, 64) guided displaceably in said support cylinder which is in operative connection with the adjusting element (38),

wherein the support cylinder (58, 62) has at least one working space (70, 72) which can be filled with a substantially incompressible fluid, in particular oil, which can optionally be introduced into the working space (70, 72) or be discharged from the working space (70, 72) and wherein the working space (70, 72) via an inlet channel (74, 76) in fluid communication with the lubricant path (33) of the crankshaft bearing (32) of the connecting rod body,

characterized ,

in that the connecting-rod body has a discharge channel (78, 80) extending from the at least one working space (70, 72) of the support cylinder (58, 62), which is used to discharge fluid from the at least one working space (70, 72) into the housing (12) is in fluid communication with a in the outer side (98) of the connecting rod body arranged outlet opening (97).

Connecting rod according to claim 11, characterized in that the support piston (60, 64) in a displaced position, which corresponds to one of at least two adjustable compression ratios, at the bottom (66, 68) of the working space and that the support piston (60, 64) in this displacement position the inlet channel (74, 76) opposite the outlet channel (78, 80) blocked.

13. Connecting rod according to claim 12, characterized in that the support piston (60, 64) in the said displacement position against the bottom (66, 68) of the working space of the support cylinder (58, 62).

14. Connecting rod according to claim 12 or 13, characterized in that the adjusting element (38) of the adjusting mechanism has a pivoting about a pivot point on the connecting rod pivotally mounted adjusting lever (39) having a first end (46) and a second end (48) wherein the adjustment lever (39) has a bearing for supporting the compression piston (16) between the fulcrum and its first end (46), that the adjustment mechanism comprises a first cylinder / piston support unit (54) having a first support cylinder (58). with a first end (46) of the adjusting lever (39) operatively connected to the first support piston (60), and with a second cylinder / piston support unit (56) is provided, which has a second support cylinder (62) with one with the second end (48) of the adjusting lever (39) operatively connected second support piston (64), and that at least the second support cylinder (62) in addition to an inlet channel (74, 76) and a Abla ufkanal (78, 80) is assigned, which can be brought into fluid communication with a arranged in the outer surface of the connecting rod outlet opening.

15. Connecting rod according to claim 14, characterized in that the adjusting lever (39) is designed as an eccentric whose center forms the pivot point of the adjusting element (38) and eccentrically to its center, the bearing for the compression piston (16).

16. Connecting rod according to one of claims 11 to 15, characterized in that the connecting rod body has a supply channel for flowable lubricant, in particular oil, from a pump (34) to the crankshaft bearing (32) and / or a compression piston bearing.

17. Connecting rod according to one of claims 11 to 16, characterized in that the support piston (60, 64) of the at least one or each cylinder / piston support unit (54, 56) has a circumferential sealing element (100) for sealing the working space (70, 72 ) of the support cylinder (58, 62) and that the circumferential sealing element (100) in a displacement position corresponding to one of at least two adjustable compression ratios, in the working space (70, 72) of the support cylinder (58, 62) the fluid connection between inlet and Outflow channel (74, 76, 78, 80) blocks, in particular the orifice (104, 102) of the inlet or the flow channel (74, 76, 78, 80) in the working space (70, 72) of the support cylinder (58, 62) closes.

18. Connecting rod according to one of claims 11 to 17, characterized in that the support piston (60, 64) at least one or each cylinder / piston support unit (54, 56) at its the bottom (66, 68) of the working space (70, 72) of the support cylinder (58, 62) facing end face (106) has a sealing element (112, 114) that the inlet and / or outlet channel (74, 76, 78, 80) at the bottom (66, 68) of the support cylinder ( 58, 62) open into the working space (70, 72) and that the sealing element (112, 114) in a displaced position, which corresponds to one of at least two adjustable compression ratios, in the working space (70, 72) of the support cylinder (58, 62) the fluid connection between inlet and outlet channel (74, 76, 78, 80) blocked, in particular the mouth opening (104, 102) of the inlet or the discharge channel (74, 76, 78, 80) in the working space (70, 72 ) of the support cylinder (58, 62) closes.

19. Connecting rod according to claim 18, characterized in that the sealing element (112) is annular and in particular an O-ring and / or that the sealing element is a lamellar sealing element or works like a lamellar seal and / or that the sealing element (114) is plate-shaped ,

20. Connecting rod according to claim 18, characterized in that the sealing element works in the manner of a labyrinth seal (105) and that either in a recess (108) is formed in the support piston (60, 64), into which projection (110) projecting from the support cylinder (58, 62) into the working space (70, 72) in said displaced position of the support piston (60, 64) immersed, or in the support cylinder (58, 62) is formed a recess into which in the said displacement position of the support piston (60, 64) immersed by the support piston (60, 64) in the working space (70, 72) projecting projection is.

21. A method for changing the compression ratio of a reciprocating piston engine, in particular a reciprocating internal combustion engine, with variable compression ratio according to one of claims 1 to 10 and / or at least one connecting rod (18) according to one of claims 11 to 20, characterized in that fluid from the at least one working space (70, 72) of the at least one support cylinder (58, 62) is discharged directly into the housing (12) of the reciprocating piston for the purpose of changing the compression ratio.

22. The method according to claim 21, characterized in that in a displacement position of the support piston (60, 64) which corresponds to one of at least two compression ratios, by the support piston (60, 64) a fluid connection between the support cylinder (58, 62) associated Inlet and drain channels (74, 76, 78, 80) are blocked.