Second generation crossover Infiniti QX50 received a bunch of innovations, the most important of which was unique motor- 2.0 liter "turbo" VC-Turbo with variable degree compression. Creation idea gasoline engine, where the compression ratio in the cylinders would be a non-constant value, is not new. So, during acceleration, when the greatest engine output is required, you can sacrifice its economy for a few seconds by reducing the compression ratio - this will prevent detonation, spontaneous combustion fuel mixture which can occur under high loads. At uniform motion on the contrary, it is desirable to increase the compression ratio in order to achieve more efficient combustion of the fuel mixture and reduce fuel consumption - in this case, the load on the engine is small and the risk of detonation is minimal. In general, everything is simple in theory, but it turned out to be not so easy to implement this idea in practice. And the Japanese designers were the first who managed to bring the idea to a production model.
The essence of the developed Nissan Corporation technology is to, depending on the required output of the motor, continuously change maximum height pistons rise (the so-called top dead center - TDC), which in turn leads to a decrease or increase in the compression ratio in the cylinders. A key detail of this system is the special fastening of the connecting rods, which are connected to crankshaft through movable block rocker. The block, in turn, is connected to an eccentric control shaft and an electric motor, which, at the command of the electronics, sets this cunning mechanism in motion, changing the slope of the rocker arms and the TDC position of the pistons in all four cylinders simultaneously.
The difference in compression ratio depending on the TDC position of the piston. On the left picture, the motor is in economy mode, on the right - in maximum efficiency mode. A: When a change in compression ratio is required, the electric motor turns and moves the drive lever. B: The drive lever turns the control shaft. C: when the shaft rotates, it acts on the lever connected to the rocker, changing the angle of the latter. D: Depending on the position of the rocker arm, TDC of the piston rises or falls, thus changing the compression ratio.
As a result, during acceleration, the compression ratio is reduced to 8:1, after which the engine goes into economy mode with a compression ratio of 14:1. Its working volume at the same time varies from 1997 to 1970 cm3. The turbo four of the new Infiniti QX50 develops 268 hp. With. and a torque of 380 Nm - significantly more than the predecessor's 2.5-liter V6 (its performance is 222 hp and 252 Nm), while consuming one third less gasoline. In addition, the VC-Turbo is 18 kg lighter than the atmospheric "six", takes up less space under the hood and reaches its maximum torque in the lower speed zone.
By the way, the compression ratio adjustment system not only increases the efficiency of the engine, but also reduces the level of vibration. Thanks to the rocker arms, the connecting rods occupy an almost vertical position during the working stroke of the pistons, while conventional engines they go from side to side (which is why the connecting rods got their name). As a result, even without balance shafts, this 4-cylinder unit runs as quietly and smoothly as a V6. But the variable TDC position using a complex system of levers is not the only feature of the new motor. By changing the compression ratio, this unit is also able to switch between two work cycles: the classic Otto, on which the bulk of the gasoline engines, and the Atkinson cycle, found mainly in hybrids. In the latter case (at a high compression ratio), due to more stroke pistons working mixture expands more, burning with greater efficiency, as a result, efficiency increases and gasoline consumption decreases.
Moving up or down lower arm changes the position of the piston relative to the combustion chamber.
In addition to two work cycles, this engine also uses two injection systems: classic distributed MPI and direct GDI, which improves fuel efficiency and avoids detonation at high compression ratios. Both systems work alternately, and at high loads - simultaneously. Positive contribution to increase Engine efficiency also introduces a special coating of the cylinder walls, which is applied by plasma spraying, and then hardened and honed. The result is an ultra-smooth “mirror-like” surface that reduces piston ring friction by 44%.
And what's the benefit?
According to engineers, the VC-T should be 27% more fuel efficient than the current naturally aspirated V6 series VQ, which it will gradually replace. This means that the passport consumption in the combined cycle will be within 7 liters. And yet to evaluate the real contribution new technology in efficiency is not yet possible, the VC-T and VQ motors are too different. The volume, the presence of boost, the number of cylinders - everything is different. Therefore, the real advantages of the Japanese development have yet to be figured out, but, like any revolution, it is interesting in itself.
Another one unique feature VC-Turbo motor is an integrated top support active vibration suppression system Active Torque Road, which is based on a reciprocating actuator. This system is controlled by an acceleration sensor that detects engine vibrations and in response generates damping vibrations in antiphase. Active mounts were first used in Infiniti in 1998 on diesel engine, but that system turned out to be too cumbersome, so it was not widely used. The project was shelved until 2009, when Japanese engineers took up its improvement. It took another 8 years to solve the problem of excess weight and dimensions of the vibration damper. But the result is impressive: thanks to ATR, the 4-cylinder unit of the new Infiniti QX50 is 9 dB quieter than its predecessor's V6!
One of those who came as close as possible to the creation serial motor with variable compression ratio brand Saab. In the Swedes, however, the upper and lower parts of the cylinder block were displaced relative to each other. And in the Infiniti / Nissan engine, changes have affected the design of the crank mechanism.
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The invention relates to mechanical engineering, primarily to heat engines, namely to a piston engine internal combustion(ICE) with variable degree compression. The technical result of the invention is to improve the kinematics of the force transmission mechanism of a reciprocating internal combustion engine, in such a way as to make it possible to control the degree of compression while reducing the reaction in the supports and second-order inertia forces. The internal combustion engine according to the invention has a piston movably mounted in the cylinder, which is pivotally connected to the connecting rod. The movement of the connecting rod is transmitted to the crank crankshaft. At the same time, in order to provide the possibility of a controlled change in the compression ratio and piston stroke, a transmission link is provided between the connecting rod and the crank, which is configured to control its movement using the control lever. The transmission link is made in the form of a transverse lever connected to the crank by means of a hinge, which is located in an intermediate position in the area between the two reference points. At one of the anchor points wishbone connected to the connecting rod, and in the other - to the control lever. The control lever is also pivotally connected to an additional crank or eccentric, which carry out control movements by shifting the control lever's rolling axis, thereby providing a change in the degree ICE compression. In addition, the rolling axis of the control arm can perform a continuous cyclic movement, synchronized with the rotation of the crankshaft. At the same time, if certain geometric relationships between the individual links of the force transfer mechanism are observed, the loads on them can be reduced and smoothness increased. ICE operation. 12 w.p. f-ly, 10 ill.
Drawings to the RF patent 2256085
The present invention relates to mechanical engineering, primarily to heat engines. The invention relates, in particular, to a reciprocating internal combustion engine (ICE) having a piston that is movably mounted in a cylinder and which is pivotally connected to a connecting rod, the movement of which is transmitted to the crankshaft crank, while a transmission link is provided between the connecting rod and the crank, which is made with the ability to control its movement using a control lever in order to ensure controlled movement of the piston, first of all, to provide the possibility of changing the compression ratio and stroke of the piston, and which is made in the form of a transverse lever, which is connected to the crank by a hinge, which is located in an intermediate position in the area between the support the point at which the transverse arm is connected to the connecting rod and the reference point at which the transverse arm is connected to the control arm, and at some distance from the line connecting both of these reference points, at which the transverse arm is connected to the control arm and the connecting rod, respectively.
From Wirbeleit F.G., Binder K. and Gwinner D., "Development of Piston with Variable Compression Height for Incrising Efficiency and Specific Power Output of Combustion Engines", SAE Techn. Pap., 900229, an internal combustion engine of this type is known with an automatically controlled compression ratio (PARSS) by changing the height of the piston, which consists of two parts, between which hydraulic chambers are formed. The change in the compression ratio is carried out automatically by changing the position of one part of the piston relative to the other by bypassing oil from one such chamber to another using special bypass valves.
The disadvantages of this technical solution include the fact that systems such as PARSS suggest the presence of a mechanism for regulating the degree of compression, located in a high-temperature and highly loaded zone (in the cylinder). Experience with systems such as PARSS showed that in transient conditions, in particular during acceleration of the car, the operation of the internal combustion engine is accompanied by detonation, since hydraulic system control does not allow for a quick and simultaneous change in the compression ratio for all cylinders.
The desire to remove the compression ratio control mechanism from the high-temperature and mechanically loaded zone led to the emergence of other technical solutions, involving a change in the kinematic scheme of the internal combustion engine and the introduction of additional elements (links) into it, the control of which ensures a change in the compression ratio.
For example, Jante A., "Kraftstoffverbrauchssenkung von Verbrennungsmotoren durch kinematische Mittel", Automobil-Industrie, No. 1 (1980), pp. 61-65, describes an internal combustion engine (the kinematic diagram of which is shown in Fig. 1), which between the crank 15 and the connecting rod 12 two intermediate links are installed - an additional connecting rod 13 and a rocker arm 14. The rocker arm 14 performs a rocking motion with the swing center at the hinge point Z. The compression ratio is controlled by changing the position of point A by turning the eccentric 16 fixed on the body . The eccentric 16 rotates depending on the engine load, while the swing center, located at the hinge point Z, moves along the arc of a circle, thus changing the position top dead piston points.
From the work of Christoph Bolling et al., "Kurbetrieb fur variable Verdichtung", MTZ 58 (11) (1997), Cs.706-711, an FEV type engine (the kinematic diagram of which is shown in Fig. 2) is also known, in which between the crank 17 and the connecting rod 12, an additional connecting rod 13 is installed. The connecting rod 12, in addition, is connected to the rocker arm 14, which performs a rocking motion with the swing center at the hinge point Z. The compression ratio is controlled by changing the position of the hinge point Z by turning the eccentric 16, mounted on engine housing. The eccentric 16 rotates depending on the engine load, while the swing center, located at the hinge point Z, moves along an arc of a circle, thus changing the position of the top dead center of the piston.
From the application DE 4312954 A1 (21.04.1993) an engine of the IFA type is known (the kinematic diagram of which is shown in Fig.3), in which an additional connecting rod 13 is installed between the crank 17 and the connecting rod 12. The connecting rod 12 is also connected to one of the ends of the rocker 14, the second end of which performs a swinging movement with the center of swing at the hinge point Z. The compression ratio is controlled by changing the position of the hinge point Z by turning the eccentric 16, which is fixed on the engine housing. The eccentric 16 rotates depending on the engine load, while the swing center, located at the hinge point Z, moves along an arc of a circle, thus changing the position of the top dead center of the piston.
The disadvantages inherent in the engines of the above designs (known from the work of Jante A., from the work of Christoph Bolling et al. and from the application DE 4312954 A1) should first of all be attributed to the insufficiently high smoothness of their operation, due to high second-order inertia forces during reciprocating translational movement of the masses, which is associated with the peculiarities of the kinematics of the mechanisms and leads to an excessive increase in the overall width or overall height power unit. For this reason, such engines are practically unsuitable for their use as engines for vehicles.
The regulation of the compression ratio in a reciprocating internal combustion engine makes it possible to solve the following problems:
Increase the average pressure Pe by increasing the boost pressure without increasing maximum pressure combustion beyond the specified limits by reducing the compression ratio as the engine load increases;
Reduce fuel consumption in the range of low and medium loads by increasing the compression ratio as the engine load decreases;
Improve the smoothness of the engine.
Adjusting the compression ratio allows, depending on ICE type reach the following benefits(for internal combustion engines with forced (spark) ignition):
While maintaining the achieved level of engine efficiency at low and medium loads, a further increase in the rated engine power is ensured by increasing the boost pressure with a decrease in the compression ratio (see figa, where the curves marked with the position x refer to a conventional engine, and the curves marked with the position y, refer to an engine with a variable compression ratio);
While maintaining the achieved level of rated engine power, fuel consumption is reduced at low and medium loads by increasing the compression ratio to the detonation-allowable limit (see Fig. 4b, where the curves marked with x refer to a conventional engine, and the curves marked with y, refer to an engine with a variable compression ratio);
While maintaining the achieved level of rated engine power, efficiency increases at low and medium loads, and the engine noise level is reduced while reducing the rated speed of the crankshaft (see Fig. 4c, where the curves marked with x refer to a conventional engine, and the curves , denoted by the position y, refer to the engine with a variable compression ratio).
Similarly to an internal combustion engine with spark ignition, the compression ratio in a diesel engine can be controlled in the following three equal directions:
With a constant displacement and rated speed, the engine power is increased by increasing the boost pressure. In this case, not efficiency increases, but power vehicle(See figa, where the curves indicated by the position x refer to a conventional engine, and the curves indicated by the position y refer to the engine with a variable compression ratio);
With a constant displacement and rated power, the average pressure Pe is increased with a decrease in the rated speed. In this case, while maintaining the power characteristics of the vehicle, the efficiency of the engine is increased by increasing the mechanical efficiency (see fig.5b, where the curves marked with x refer to a conventional engine, and the curves marked with y refer to an engine with a variable compression ratio );
The existing large displacement engine is not replaced by a small displacement engine, but of the same power (see Fig.5c, where the curves marked with x refer to a conventional engine, and the curves marked with y refer to an engine with a variable compression ratio ). In this case, the efficiency of the engine is increased in the range of medium and full loads, and the weight and dimensions of the engine are also reduced.
The present invention was based on the task of improving the kinematics of a reciprocating internal combustion engine in such a way that, at low structural costs, it is possible to control the compression ratio while simultaneously reducing the reaction in the supports and second-order inertia forces.
With respect to a reciprocating internal combustion engine of the type indicated at the beginning of the description, this problem is solved according to the invention due to the fact that the length of the side located between the reference point at which the control arm is connected to the control arm and the reference point at which the control arm is connected to the connecting rod, the length of the side, located between the reference point at which the transverse arm is connected to the control arm and the pivot point by which the transverse arm is connected to the crank, and the length of the side located between the pivot point at which the transverse arm is connected to the connecting rod and the pivot point by which the transverse arm is connected to the crank , satisfy the following relations in terms of the crank radius:
According to one of the preferred embodiments of the piston internal combustion engine proposed in the invention, the transverse lever is made in the form wishbone, at the vertices of which there are reference points, in which the transverse lever is connected to the control lever and connecting rod, and the hinge, by which the transverse lever is connected to the crank.
Preferably, the length l of the connecting rod and the length k of the control lever, as well as the distance e between the axis of rotation of the crankshaft and the longitudinal axis of the cylinder, satisfy the following ratios in terms of the radius r of the crank:
In the case where the control arm and connecting rod are located on the same side of the transverse arm, the distance f between the longitudinal axis of the cylinder and the point of articulation of the control arm with the engine housing and the distance p between the axis of the crankshaft and said point of articulation should preferably satisfy in terms of radius r of the crank to the following relations:
In the same case, when the control lever and connecting rod are located along different sides of the control arm, the distance f between the longitudinal axis of the cylinder and the point of articulation of the control arm and the distance p between the axis of the crankshaft and said point of articulation should preferably satisfy, in terms of the radius r of the crank, the following relations:
According to a further preferred embodiment of the reciprocating internal combustion engine according to the invention, the pivot point of the control arm is movable along a controlled path.
Preferably, it is also possible to fix the pivot point of the control arm in various adjustable angular positions.
In accordance with another preferred embodiment of the reciprocating internal combustion engine proposed in the invention, it is possible to adjust the angular position of the pivot point of the control lever depending on the values characterizing the operating mode of the internal combustion engine and operating parameters of the internal combustion engine.
According to another preferred embodiment of the reciprocating internal combustion engine according to the invention, it is possible to move the pivot point of the control lever along a controlled path, synchronized with the rotation of the crankshaft.
In another preferred embodiment of the reciprocating internal combustion engine proposed in the invention, it is possible to synchronize with the rotation of the crankshaft the movement of the pivot point of the control lever along a controlled trajectory and the possibility of controlling the phase shift between the movement of this point and the rotation of the crankshaft, depending on the values characterizing the operating mode of the internal combustion engine and operating parameters ICE.
In accordance with the following preferred embodiment of the piston internal combustion engine proposed in the invention, it is possible to synchronize the movement of the pivot point of the control lever along the controlled path, synchronized with the rotation of the crankshaft, while providing the possibility of changing gear ratio between the movement of the specified point and the rotation of the crankshaft.
The piston ICE 1 proposed in the invention is shown in figa and 6b and has a housing 2 with a cylinder 3 and a piston 4 installed in it, a connecting rod 6, which is pivotally connected at one end to the piston 4, a crank 8 of the crankshaft installed in the housing 2, trailed a connecting rod 10, also called a control lever 10 and hinged at one end to the body 2, and a triangular transverse lever 7, which at one of its vertices is pivotally connected to the second end of the connecting rod 6, its second vertex is pivotally connected to the crank 8, and its third vertex is pivotally connected connected to the connecting rod 10. To control the degree of compression, the swing axis of the trailing rod 10, i.e. point Z of its swivel has the ability to move along a controlled trajectory, determined, for example, by an eccentric or an additional crank 11.
Depending on the position of the swing axis of the trailer connecting rod, the piston internal combustion engine proposed in the invention has two design options (see figa and 6b):
In the first variant (Fig. 6a), the horizontal plane in which the swing axis of the trailer connecting rod 10 lies, i.e. the point Z of its articulation is located above the point of connection of the crank 8 with the transverse lever 7 when the crank is at its top dead center or, in other words, the connecting rod 10 and the connecting rod 6 are located on one side of the transverse lever 7;
In the second variant (fig.6b) the horizontal plane in which lies the swing axis of the trailer connecting rod 10, i.e. the point Z of its articulation is located below the point of connection of the crank 8 with the transverse lever 7 when the crank is at its top dead center or, in other words, the connecting rod 10 and the connecting rod 6 are located on opposite sides of the transverse lever 7.
Changing the position of the Z point of the swivel of the trailer arm, i.e. its swing axis, allows, by a simple control movement carried out by an additional crank, respectively regulating eccentric, to change the compression ratio. In addition, the point Z of the articulation of the trailer arm, i.e. its swing axis can make continuous cyclic movement, synchronized with the rotation of the crankshaft.
As shown in Fig.7, proposed in the invention piston internal combustion engine has significant advantages over known systems(described by Jante A., Christoph Bolling et al. and DE 4312954 A1), as well as before the usual crank mechanism(CM) regarding the smoothness of its operation.
However, these advantages can be achieved only if certain geometric relationships are observed, namely, when correct selection lengths of individual elements and their positions relative to the axis of the crankshaft.
According to the present invention, it is important to determine the dimensions of the individual elements (in relation to the radius of the crank) and the coordinates of the individual hinges of the force transmission mechanism, which can be achieved by optimizing such a mechanism through kinematic and dynamic analysis. The purpose of optimizing such a mechanism described by nine parameters (Fig. 8) is to reduce the forces (load) acting on its individual links to a minimum possible level and in improving the smoothness of its work.
Below with reference to Fig.9 (9a and 9b), which shows the kinematic internal combustion engine scheme shown in Fig.6 (6a and 6b, respectively), explains the principle of operation of the adjustable crank mechanism. During the operation of the internal combustion engine, its piston 4 performs in the cylinder a reciprocating forward movement, which is transmitted to the connecting rod 6. The movement of the connecting rod 6 is transmitted through the reference (hinge) point B to the transverse lever 7, the freedom of movement of which is limited due to its connection with the trailer connecting rod 10 at the reference (hinge) point C. If the point Z of the hinged connection of the trailer connecting rod 10 is fixed, then the reference point C of the transverse lever 7 can move along an arc of a circle, the radius of which equal to length of the trailer connecting rod 10. The position of such a circular trajectory of movement of the reference point C relative to the engine housing is determined by the position of the point Z. When the position of the point Z of the swivel of the trailer connecting rod changes, the position of the circular trajectory along which the reference point C can move, which allows you to influence the trajectories of movement of other elements crank mechanism, primarily on the position of the top dead center. piston 4. The pivot point Z of the trailer connecting rod preferably moves in a circular path. However, the point Z of the hinged connection of the trailer connecting rod can also move along any other given controlled trajectory, while it is also possible to fix the point Z of the hinged connection of the trailer connecting rod in any position of the trajectory of its movement.
The transverse lever 7 is also connected by a hinge A to the crank 8 of the crankshaft 9. This hinge A moves along a circular path, the radius of which is determined by the length of the crank 8. The hinge A occupies an intermediate position when viewed along the line connecting the reference points B and C of the transverse lever 7. The presence of a kinematic connection of the reference point C with the trailing connecting rod 10 allows you to influence its translational movement along the longitudinal axis 5 of the piston 4. The movement of the reference point B along the longitudinal axis 5 of the piston is determined by the trajectory of the reference point C of the transverse lever 7. allows you to control the reciprocating movement of the piston 4 through the connecting rod 6 and thereby adjust the position of the top dead center. piston 4.
In the embodiment shown in Fig. 9a, the connecting rod 10 and the connecting rod 6 are located on one side of the transverse arm 7.
By turning the control link made in the form of an additional crank 11 from the approximately horizontal position shown in FIG. piston 4 up and thereby increase the compression ratio.
On fig.9b shows a kinematic diagram of a different ICE variant, differing from the diagram shown in figa only in that the trailer connecting rod 10, together with the control link made in the form of an additional crank 11, respectively, the regulating eccentric, and the connecting rod 6 are located on opposite sides of the transverse lever 7. In all other respects, the principle of operation shown in Fig. 9b of the crank mechanism is similar to the principle of operation of the crank mechanism shown in Fig. 9a, in which the trailer connecting rod 10 and the connecting rod 6 are located on one side of the transverse lever 7.
Figure 10 shows another kinematic diagram of the crank mechanism of the piston internal combustion engine, which shows the positions of certain points of this crank mechanism and on which the hatching indicates the optimal areas within which, taking into account the above-mentioned optimal ranges for the lengths and positions of the elements of the crank mechanism, the reference point B of the swivel joint of the transverse arm 7 with the connecting rod 6, the reference point C of the swivel joint of the transverse arm 7 with the trailer connecting rod 10 and the point Z of the swivel joint of the trailer connecting rod 10 can move. To ensure particularly smooth operation of the internal combustion engine with an exceptionally low load on individual elements and links of its crank mechanism geometric parameters(length and position) of the elements and links of this crank mechanism must satisfy certain, preferred ratios. The lengths of the sides a, b and c of the triangular wishbone 7, where a denotes the length of the side located between the reference point B of the connecting rod and the reference point C of the trailer connecting rod, b denotes the length of the side located between the hinge A of the crank and the reference point C of the trailer connecting rod, and c denotes the distance between the hinge A of the crank and the reference point B of the connecting rod, can be described by the following inequalities depending on the radius r, which is equal to the length of the crank 8:
The length l of the connecting rod 6, the length k of the connecting rod 10 and the distance e between the axis of rotation of the crankshaft 9 and the longitudinal axis 5 of the cylinder 3, which is also the longitudinal axis of the piston moving in this cylinder, according to the preferred embodiment, satisfy the following relationships:
For the variant shown in figa, in which the connecting rod 6 and the connecting rod 10 are located on one side of the transverse arm 7, you can also set the optimal ratio of sizes. In this case, the distance f between the longitudinal axis 5 of the cylinder and the point Z of the swivel of the trailer arm 10 to its control link, as well as the distance p between the axis of the crankshaft and the specified point Z of the swivel, according to the preferred embodiment, satisfy the following relationships:
When the trailer connecting rod and the connecting rod are located on opposite sides of the transverse lever, the optimal distance f between the longitudinal axis of the piston and the point Z of the hinged connection of the trailer lever to its regulating link, as well as the optimal distance p between the axis of the crankshaft and the indicated point Z of the hinged connection, can be selected based on the following ratios:
CLAIM
1. piston engine internal combustion engine (ICE), having a piston (4), which is movably mounted in the cylinder and which is pivotally connected to the connecting rod (6), the movement of which is transmitted to the crank (8) of the crankshaft (9), while between the connecting rod (6) and the crank (8) a transmission link is provided, which is made with the possibility of controlling its movement using the control lever (10) in order to ensure controlled movement of the piston, primarily to provide the possibility of changing the compression ratio and stroke of the piston, and which is made in the form of a transverse lever (7), which is connected to the crank (8) by a hinge (A), which is located in an intermediate position in the area between the reference point (B), in which the control arm (7) is connected to the connecting rod (6), and the reference point (C), in which the transverse lever (7) is connected to the control lever (10), and at some distance from the line connecting both of these reference points (B, C), in which the transverse lever (7) is connected to the control lever (10) and connecting rod (6 ) respectively, characterized in that the length of the side (a) located between the reference point (C), in which the transverse arm (7) is connected to the control arm (10), and the reference point (B), in which the transverse arm (7) connected to the connecting rod (6), the length of the side (b) located between the reference point (C) in which the control arm (7) is connected to the control arm (10) and the pivot (A) by which the control arm (7) is connected to crank (8), and the length of the side (c) located between the reference point (B), in which the transverse arm (7) is connected to the connecting rod (6), and the hinge (A), by which the transverse arm (7) is connected to the crank ( 8), satisfy the following ratios in terms of the radius (r) of the crank:
6. piston engine 4 or 5, characterized in that the pivot point (Z) of the control lever (10) is movable along a controlled path.
7. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to adjust the position of the point (Z) of the swivel of the control lever (10) using an additional crank resting on the hinge.
8. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to adjust the position of the point (Z) of the swivel of the control lever (10) using an eccentric.
9. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to fix the point (Z) of the swivel of the control lever (10) in various adjustable angular positions.
10. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to adjust the angular position of the point (Z) of the swivel of the control lever (10) depending on the values characterizing the operating mode of the internal combustion engine and the operating parameters of the internal combustion engine.
11. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to synchronize with the rotation of the crankshaft the movement of the point (Z) of the swivel of the control lever (10) along a controlled trajectory.
12. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to synchronize with the rotation of the crankshaft (9) the movement of the point (Z) of the swivel of the control lever (10) along a controlled trajectory and the possibility of controlling the phase shift between the movement of this point ( Z) and rotation of the crankshaft (9) depending on the values characterizing the operating mode of the internal combustion engine and the operating parameters of the internal combustion engine.
13. Reciprocating internal combustion engine according to claim 4 or 5, characterized in that it is possible to synchronize with the rotation of the crankshaft (9) the movement of the point (Z) of the swivel of the control lever (10) along a controlled trajectory, while it is possible to change the gear ratio between the movement specified point (Z) and rotation of the crankshaft (9).
The idea of creating a gasoline engine, where the compression ratio in the cylinders would be a variable value, is not new. So, during acceleration, when the greatest engine output is required, you can sacrifice its economy for a few seconds by reducing the compression ratio - this will prevent detonation, spontaneous combustion of the fuel mixture, which can occur at high loads. With uniform movement, on the contrary, it is desirable to increase the compression ratio in order to achieve more efficient combustion of the fuel mixture and reduce fuel consumption - in this case, the load on the engine is small and the risk of detonation is minimal.
In general, everything is simple in theory, but it turned out to be not so easy to implement this idea in practice. And the Japanese designers were the first who managed to bring the idea to a production model.
The essence of the technology developed by Nissan is to continuously change the maximum piston lift (the so-called top dead center - TDC), depending on the required engine output, which in turn leads to a decrease or increase in the compression ratio in the cylinders. A key detail of this system is the special fastening of the connecting rods, which are connected to the crankshaft through a movable block of rocker arms. The block, in turn, is connected to an eccentric control shaft and an electric motor, which, at the command of the electronics, sets this cunning mechanism in motion, changing the slope of the rocker arms and the TDC position of the pistons in all four cylinders simultaneously.
The difference in compression ratio depending on the TDC position of the piston. On the left picture, the motor is in economy mode, on the right - in maximum efficiency mode. A: When a change in compression ratio is required, the electric motor turns and moves the drive lever. B: The drive lever turns the control shaft. C: when the shaft rotates, it acts on the lever connected to the rocker, changing the angle of the latter. D: Depending on the position of the rocker arm, TDC of the piston rises or falls, thus changing the compression ratio.
As a result, during acceleration, the compression ratio is reduced to 8:1, after which the engine goes into economy mode with a compression ratio of 14:1. Its working volume at the same time varies from 1997 to 1970 cm 3 . The turbo four of the new Infiniti QX50 develops 268 hp. With. and a torque of 380 Nm - significantly more than its predecessor's 2.5-liter V6 (its performance is 222 hp and 252 Nm), while consuming one third less gasoline. In addition, the VC-Turbo is 18 kg lighter than the atmospheric "six", takes up less space under the hood and reaches its maximum torque in the lower speed zone.
By the way, the compression ratio adjustment system not only increases the efficiency of the engine, but also reduces the level of vibration. Thanks to the rocker arms, the connecting rods occupy an almost vertical position during the working stroke of the pistons, while in conventional engines they go from side to side (which is why the connecting rods got their name). As a result, even without balance shafts, this 4-cylinder unit runs as quietly and smoothly as a V6.
But the variable TDC position using a complex system of levers is not the only feature of the new motor. By changing the compression ratio, this unit is also able to switch between two work cycles: the classic Otto, which operates the majority of gasoline engines, and the Atkinson cycle, found mainly in hybrids. In the latter case (with a high compression ratio), due to the larger stroke of the pistons, the working mixture expands more, burning with greater efficiency, as a result, efficiency increases and gasoline consumption decreases.
In addition to two working cycles, this engine also uses two injection systems: classic distributed MPI and direct GDI, which improves fuel efficiency and avoids detonation at high compression ratios. Both systems work alternately, and at high loads - simultaneously. A positive contribution to increasing engine efficiency is also made by a special coating of the cylinder walls, which is applied by plasma spraying, and then hardened and honed. The result is an ultra-smooth “mirror-like” surface that reduces piston ring friction by 44%.
Another unique feature of the VC-Turbo motor is the Active Torque Road active vibration dampening system, which is based on a reciprocating actuator, integrated into its upper mount. This system is controlled by an acceleration sensor that detects engine vibrations and in response generates damping vibrations in antiphase. Active bearings were first used in Infiniti in 1998 on a diesel engine, but that system turned out to be too cumbersome, so it was not widely used. The project was shelved until 2009, when Japanese engineers took up its improvement. It took another 8 years to solve the problem of excess weight and dimensions of the vibration damper. But the result is impressive: thanks to ATR, the 4-cylinder unit of the new Infiniti QX50 is 9 dB quieter than its predecessor's V6!
VC-T engine. Image: Nissan
Japanese automaker nissan motor introduced a new type of gasoline internal combustion engine, which in some respects surpasses advanced modern diesel engines.
The new Variable Compression-Turbo (VC-T) engine is capable of change the compression ratio gaseous combustible mixture, that is, change the stroke of the pistons in ICE cylinders. This setting is usually fixed. Apparently, the VC-T will be the world's first ICE with a variable compression ratio.
The compression ratio is the ratio of the volume of the over-piston space of the cylinder of an internal combustion engine when the piston is in the lower dead center(total volume of the cylinder) to the volume of the over-piston space of the cylinder when the piston is at top dead center, that is, to the volume of the combustion chamber.
Increasing the compression ratio in general case increases its power and increases the efficiency of the engine, that is, it helps to reduce fuel consumption.
In conventional gasoline engines, the compression ratio is usually between 8:1 and 10:1, and in sports cars And racing cars can reach 12:1 or more. When the compression ratio is increased, the engine needs fuel with a higher octane rating.
VC-T engine. Image: Nissan
The illustration shows the difference in piston stroke by varying degrees compression: 14:1 (left) and 8:1 (right). In particular, the mechanism of changing the compression ratio from 14:1 to 8:1 is demonstrated. It happens in this way.
- If it is necessary to change the compression ratio, the module is activated Harmonic Drive and moves the actuator lever.
- The actuator lever turns the drive shaft ( control shaft on the diagram).
- When the drive shaft turns, it changes the angle of inclination multi-link suspension (multi-link on the diagram)
- A multi-link suspension determines the height to which each piston is able to rise in its cylinder. Thus, the compression ratio changes. The bottom dead center of the piston, apparently, remains the same.
Changing the compression ratio in an internal combustion engine can be compared in a sense to changing the angle of attack in a controllable pitch propeller, a concept that has been used for many decades in air and propellers. The variable pitch of the propeller allows to maintain the propulsion efficiency close to optimal, regardless of the speed of the carrier in the stream.
The technology of changing the compression ratio of the internal combustion engine makes it possible to maintain engine power while meeting strict standards for engine efficiency. This is probably the most real way comply with these regulations. “Everyone is now working on variable compression and other technologies to greatly improve the efficiency of gasoline engines,” says James Chao, managing director for Asia Pacific and consultant for IHS. “For at least the last twenty years or so.” . It is worth mentioning that in 2000 Saab company showed a prototype of such a Saab Variable Compression (SVC) engine for the Saab 9-5, for which it won a number of awards at technical exhibitions. Then the Swedish company was bought by the concern General Motors and stopped working on the prototype.
Saab Variable Compression (SVC) engine. Photo: Reedhawk
The VC-T engine is expected to hit the market in 2017 with the Infiniti QX50. The official presentation is scheduled for September 29 at Paris Motor Show. This two-liter four-cylinder engine will have about the same power and torque as the 3.5-liter V6 it takes its place, but deliver 27% fuel savings compared to it.
Nissan engineers also say that the VC-T will be cheaper than today's advanced turbocharged diesel engines and will fully comply with modern nitrogen oxide and other emissions regulations. exhaust gases- such rules apply in the European Union and some other countries.
After Infiniti new it is planned to equip other nissan cars and possibly partner company Renault. 
VC-T engine. Image: Nissan
It can be assumed that the complicated internal combustion engine design at first, it is unlikely to be reliable. It makes sense to wait a few years before buying a car with a VC-T engine, unless you want to participate in experimental technology testing.
Recently, at the Paris Motor Show, the Infiniti brand (read, Renault-Nissan alliance) introduced a variable compression engine. The proprietary Variable Compression-Turbocharged (VC-T) technology allows you to vary this very degree, literally sucking all the juice out of the engine.
In an "ideal universe" the rule is simple - the higher the compression ratio fuel-air mixture, all the better. The mixture expands as much as possible, the pistons move as if wound, therefore, the power and efficiency of the motor are maximum. In other words, the fuel is burned extremely efficiently.
Everything would be great if not for the very nature of the fuel. In the course of bullying, his patience once comes to a limit: the more evenly the mixture burns out, the better, but at high loads ( high degree compression, high speed) the mixture begins to explode rather than burn. This phenomenon is called detonation, and this thing is quite destructive. The walls of the combustion chamber and the piston itself experience serious shock loads and are gradually, but rather quickly destroyed. In addition, the efficiency of the motor drops - normal operating pressure falls on the piston.
Thus, the most profitable option is when the engine in any mode operates on the verge of detonation, preventing this phenomenon. Infiniti engineers drew up a graph on which they outlined for themselves the effective operating modes of the engine depending on the load, speed and compression ratio of the fuel-air mixture. (Actually, fuel combustion efficiency can be improved in other ways, such as increasing the number of valves per cylinder, adjusting their schedule, even choosing a place above the piston where the injection of a portion of fuel is directed. Of course, we remember this.) The first two parameters, clear, depend on external factors, and from the careful selection of the transmission. And the third - the compression ratio - was also decided to change in the range from 8:1 to 14:1.
Technically, this looks like an introduction to the design of the crank mechanism. additional element- rocker arms between connecting rod and crankshaft. The rocker is controlled by an electric motor - the lever can be shifted in such a way that the piston stroke range varies within 5 mm. This is enough to significantly change the compression ratio.
There are no advantages without disadvantages. At first glance, they are obvious: an increase in the complexity of the design, some weight gain ... However, it’s a sin to complain about these minuses - the engine turned out to be very balanced, due to which the balancing shafts were removed from the design. It is also likely that the engine is particularly sensitive to the brand and quality of fuel. It seems that this problem - at least to a large extent - is solved by software methods.
Since the word Turbocharged is present in the name of the technology, it is obvious that such engines will be turbocharged. The first of them - a two-liter 270-horsepower will get under the hood of the Infiniti QX50 crossover. It is claimed that the engine with variable compression ratio consumes as much as 27% less fuel than a conventional motor of the same size. The number is extremely impressive. We must think that environmental friendliness (the number of emissions harmful substances) is top notch.
