DE19506963A1 - Variable stroke combustion engine - Google Patents

Abstract

The engine has a mechanism replacing the usual crank gear, with a crankshaft having a connecting rod of length greater than that of the crank. An intermediate element is connected to the connecting rod via a rotating linkage and directly or indirectly, rigid or movable with the piston. A mechanism (A) retains the movement of connecting rod-intermediate link-coupling point to a certain path, and a second mechanism (B) alternates between two procedures. It ensures that the tangent of the path is vertical to the connecting rod when the angle between connecting rod and crank is zero, and that the direction of movement does not change at this point. A third mechanism (C) connects the above path with rotation direction changes of the crankshaft.

Description

Changeover motor (in the following: WHM) can replace the conventional Gasoline engines are used.

The theoretical thermodynamic efficiency of the gasoline engine depends only on the degree of expansion (see Fig. 6):

e = 1- (V1: V2) ^0.4 , (equation 1)

V1 - combustion chamber volume,
V2 volume at the end of the expansion.

In conventional gasoline engines, the degree of expansion is due to the design Compression degree equal. The theoretical thermodynamic efficiency of conventional gasoline engines is thus determined by the degree of compression: je greater the degree of compression, the greater the efficiency, d. H. like this fuel-efficient engine. However, the increase in the degree of compression is limited by chemical properties of the fuels: From one the value detonates the fuel by itself. The degree of compression of Most car engines of today's technology is limited to about 10 when gasoline with unleaded gasoline and about 25 in the diesel. leaded Although fuels allow a greater degree of compression, but are more expensive and especially harmful to the environment.

This problem is solved by a design in which the degree of expansion is greater than the degree of compression: at the stroke, the stroke is greater than the compression stroke. (Hence the name "change-stroke motor".) See Fig. 7: Course of the cycle in the PV diagram (WHM - f, a, b, g, c, d, in the conventional motor - f, a, b , g, h).

The crank gear of the engine is mentioned by the protection claims Mechanism that ensures that the degree of expansion is greater than that Compression degree is "replaced, which consists of the following components (Es  First, the individual components are listed with their functions and then their compositions and functions individually explained in more detail, if necessary Examples):

• 1) crankshaft ( 1 ) (see Fig. 1A), with the crank a connecting rod ( 2 ) with P <K (P - full length, K - crank length) is coupled,
• 2) intermediate member ( 3 ), which is coupled by a hinge with the connecting rod ( 2 ) and is connected directly or indirectly, movably or immovably to the piston ( 4 ),
• 3) Mechanism A ( 5 ) holding the movements of the connecting rod intermediate coupling point on a path determined by the mechanism A,
• 4) Mechanism B ( 6 ), which reverses the direction of movement of the connecting rod-link coupling point in the transition from the intake to the working stroke,
• 5) mechanism C ( 8 ), the random reversals of the direction of movement of the connecting rod-intermediate coupling point ( 9 ) and the crankshaft rotation direction in the MT does not allow.

By way of illustration, let us now consider a single simplified (without further description of Mechanisms B and C) schematic of the "mechanism that causes the degree of expansion to be greater than the degree of compression" (see Fig. 2):

To the crankshaft ( 1 ) a connecting rod ( 2 ) is coupled by a rotary joint. On the piston ( 4 ), the rod ( 3 ) is fixed, which is coupled by a hinge at its other end to the connecting rod.

The role of the mechanism A takes over a second crankshaft connecting rod assembly ( 5 ) which is "mirrored" to the rod axis ( 7 ) and whose connecting rod is also coupled by a hinge to the rod. The crankshafts are connected by identical gears ( 8 ) and rotate synchronously and in opposite directions (gears are only drawn in positions "a"). This arrangement holds the connecting rod rod coupling point on the vertical straight track. (In the simplest case, the role of the mechanism A could also take over a crosshead with corresponding guide surfaces, such as in the piston steam engine).

In the WHM, the path of the axle of the swivel joint through which the connecting rod end is connected to the piston rod (coupling axle track) at the long stroke has a certain distance D = PK (track distance) from the main axis of the crankshaft (see Fig. 1A).

As a result, when the piston is going down / up, the connecting rod reaches its horizontal position precisely when the connecting rod / crank coupling point ( FIGS. 2, 9) is furthest from the coupling axle track (FIGS . 1, i; 1, u). At this point (furthermore: center point, MT), the connecting rod can "tip over" downwards / upwards ( FIG. 1, i / u), which makes the long stroke possible.

When the piston moves from the TDC to the MT (see Figures 1, a to i), the force is transmitted to the crank by pushing the connecting rod from the MT to the bottom dead center of the power stroke (AUT) ( Figures 1, i to a) ) - by pulling the connecting rod. Mechanism C does not allow accidental reversals of the direction of movement of the connecting rod linkage point ( 9 ) in the MT. (In the MT, the connecting rod intermediate coupling point ( 9 ) can move both "up" and "down" with the same direction of rotation of the crankshaft, which is likely due to the inertial forces only when starting the engine.)

In Fig. 1 and 2, individual positions of the WHM are shown schematically. Fig. 3 shows WHM piston-traction characteristic with the connecting rod-to-crank ratio 2: 1, β = 15 ° (curve 1) and 3: 1, β = 20 ° (curve 2).

Special features of the WHM mode of operation:

• 1) The working cycle in the WHM does not run in two, but in three full ones Revolutions of the motor shaft.
• 2) In contrast to conventional constructions, the crankshaft in the WHM rotates at different clock angles by different angles, the size of which depends in detail on the connecting rod-to-crank ratio (see Equations 5 to 8 below and FIG. 4 for the power stroke). , The working stroke always corresponds to the largest angle, which has some advantages, which are described below.
• 3) The power stroke and the exhaust stroke always take two full turns of the Motor shaft on.
• 4) The connecting rod-to-crank ratio determines the piston characteristic. At 5.83, the speed of the piston is nearly one full revolution of the angular velocity of the motor shaft (see Fig. 4, curve 5).
• 5) The suction and compression stroke always take one complete revolution of the motor shaft. Portions of the suction and compression stroke at this revolution depend on the final angle (β) of the connecting rod to the horizontal in the EUT (see Fig. 2, h and Fig. 3). The larger β, the shorter the Einsaugetakt and longer the compression stroke.
• 6) With appropriate adjustment of mechanism B or without him, can the WHM can also be operated without a short stroke, which increases the size of the theoretical thermodynamic efficiency is waived and only his special piston characteristic is used. The valve control and Ignition / injection must in this case to a 4-turn cycle be rebuilt.
• 7) Also, the WHM can be operated in the reverse direction, which its piston characteristic in contrast to the conventional engines changed greatly: depending on the direction of rotation, he always does either in the long stroke a fast gear down and a slow gear up or vice versa.

The following are functions of the most important parameters of the WHM:
Length of the long stroke:

H = 4 _* (P _* K) ^0.5 , (equation 2)

Length of the short stroke:

h = 2 _* (P _* K) ^0.5 - tan β _* (PK) (equation 3)

β-angle between the connecting rod and perpendicular to the coupling axis line straight line, in the bottom dead center in Einsaugetakt (EUT). Fig. 2, h shows this angle, which is determined by the construction. The larger it is, the smaller the short stroke, the greater the degree of expansion and the efficiency. Displacement value of the mechanism B, which allows to reach the chosen angle β:

a = (P - K) _* (1 / cos β-1) (equation 4)

The individual clocks correspond to the following angles of crankshaft rotation:
Power stroke:

W _E = 2 _* pi + 2 _* arccos ((P - K) / (P + K) (Eq. 5)

Exhaust stroke:

W _A = 2 _* pi - 2 _* arccos ((P - K) / (P + K)) (Eq. 6)

One eye clock:

W _e = 0.5 _* W _e - β (equation 7)

Compression stroke:

W _K = 2 _* pi - W _e (Eq. 8)

Absolute increase in efficiency (in percent of the chemical energy converted to mechanical form):

de _A = ((1 / k) ^0.4 - 1 / x) ^0.4 ) _* 100, (equation 9)

k - degree of compression, x - degree of expansion.

x = H _* (k-1) / h + 1, (Eq. 10)

Overall, the invention achieves the following advantages:

• 1) Increase of the theoretical thermodynamic efficiency.
• 2) Great flexibility of construction.
• 3) more complete combustion of fuels.
• 4) Enabling the use of cheaper fuels.
• 5) Reduced environmental impact from colder and chemically more environmentally friendly Exhaust gases.
• 6) Lower energy losses through premature opening of the exhaust valves.
• 7) Lower operating costs.
• 8) Reduction of the energy requirement in certain embodiments.  
• 9) Enlargement of the mechanical efficiency.
• 10) Less wear.

1) Increase of the theoretical thermodynamic efficiency

Additional expansion achieves an increase in efficiency (see equation 9). To illustrate (assumptions: the maximum temperature of the Gas is reached at top dead center):

<11.5% absolute compared to gasoline engine with compression ratio 10,
<8.5% absolute compared to the compression ratio 22 diesel engine.

2) Great flexibility of construction (short / long huber)

In the case of WHM, very variable characteristics of the change in the lever arm after crankshaft rotation can be achieved by means of various connecting rod-to-crank ratios. The WHM can be "short-stroke" than the conventional short-hauler and at the same time possess all "long-throwing" properties. Proper choice of the conrod-to-crank ratio will minimize the cooling of the combustion products "out" to increase the practical efficiency of the engine and achieve better torque characteristics (see Fig. 5).

3) more complete combustion of fuels

More complete combustion is achieved through longer lasting work cycles allows.

4) Enabling the use of cheaper fuels

The usual efficiency can also at the lower maximum compression pressure be achieved: use of cheaper fuels is possible.

5) Reduced environmental impact from colder and chemically more environmentally friendly exhaust

Due to greater expansion of the combustion products is the exhaust gas temperature  200 ° C for the gasoline engine and approx Thermal load of the environment reduced. Better combustion does not reduce completely burned and polluting components of the exhaust gases.

6) Lower energy losses due to premature opening of the exhaust valves

To reduce the pressure in the cylinder before the exhaust stroke, are in the conventional engines, the exhaust valves before the end of the power stroke opened, which reduces the theoretical thermodynamic efficiency. in the WHM leads to the premature opening of the valves to much lower Efficiency losses, since the degree of expansion is significantly greater (final pressure or temperature is much lower).

7) Lower operating costs

Lower temperatures allow lower oil consumption and a lower oil consumption predict a longer period between oil changes.

8) Reduction of the energy requirement in certain embodiments

The premature opening of the exhaust valves described in section 6 and the associated efficiency reduction can be achieved by the following Special feature in the design of the engine can be completely avoided: in the bottom Part of the cylinder walls, close to the AUT are like the two-stroke engine exhaust ports appropriate. When reaching the AUTs can now under the Final pressure exhaust gases escape through the openings.

9) Enlargement of the mechanical efficiency

It is possible to design the WHM so that the piston rests on the cylinder walls no lateral forces. This will cause the friction force between the piston and reduces the cylinder walls, the mechanical efficiency increases.

10) Less wear

According to 9) the wear of the piston and the cylinder walls is reduced.  

embodiment

An embodiment of the invention is shown in the drawings: Fig. 8, Fig. 9, Fig. 10. Its torque characteristic compared to the torque characteristic of the conventional engine is shown in Fig. 5 (assumptions: full combustion and maximum temperature of the gases are reached at top dead center, expansion is adiabatic, friction losses neglected).

As a motor shaft, a crankshaft with crank lengths K = 220 mm is used with a P = 60 mm long connecting rod is connected.

The intermediate link is a rod that is direct and immovable with the piston connected is.

The connecting rod linkage point has a straight track. When Mechanism A uses a second identical crankshaft with its connecting rod. To the rod with the piston without lateral shifts straight on the Cylinder axis to move, the crankshafts are using the same gears connected so that they rotate synchronously and oppositely. The definition A specific crankshaft as a motor shaft is purely formal: any of them can be regarded as a motor shaft.

Mechanism B (switching from the long to the short stroke in Einsaugetakt and vice versa in the power stroke) is shown in FIG. 9 Hubwechselvorrichtung.

The distance of the crankshaft axis from the path of movement of the connecting rod-linkage coupling point is according to equation D = P-K in this case

60-20 = 40mm.

The angle (β) of the connecting rod to the horizontal at the end of the intake stroke (in EUT) is set equal to 20 ° in the construction of this embodiment. The Compression degree is the same: k = 10 (22); (The values given in brackets are suitable for one Variable displacement diesel engine with corresponding parameters).  

The main parameters of the embodiment are as above calculated equations and have the following values (linear measures in mm, angle in radians):

The long stroke: | H = 138,564; The short stroke: h = 54.723; Degree of expansion: x = 23.789 (54.174); Theoretical thermodynamic efficiency: e = 0.719 (0.777).

Increase of the theoretical thermodynamic efficiency (compared with a conventional gasoline engine with the same degree of compression: K = 10 (22)):

absolute: de _A = 11.66% (8.79%); relative: de _R = 19.38% (11.24%).

The motor is drawn in position at the beginning of the power stroke (see Fig. 8). The piston ( 1 ) moves through the rod ( 2 ), the bolts ( 3, 4 ), the connecting rods (( 5, 6 ) and the crankshafts ( 7, 8 ) extending in the direction indicated by the main axes ( 9, 10 ) in bearings of the motor housing 18. The crankshafts are connected by the gears 11, 12. The camshaft 14 , which controls the valves 15, 16 , simultaneously controls the ignition or high pressure pump in the diesel engine ), is driven by the crankshaft ( 8 ) by chain or toothed belt drive ( 13 ) (stocky: 3: 1)). During the intake and compression stroke, the piston moves in the short stroke ( FIG. 2), which causes the largest permissible compression of the mixture during the compression stroke. When working and Auspufftakten he moves in the long stroke ( Fig. 3).

The Hubwechselvorrichtung ( 17 ) ensures that the eccentric pin ( 3, 4 ) in each third revolution of the crankshaft ( 7, 8 ) in the TDC before the intake stroke to the connecting rods ( 5, 6 ) coupled accordingly and from the rod ( 2 ) be decoupled. At the end of the compression stroke in the TDC area they are fixed again in the original position. From the beginning of the intake stroke to the end of the compression stroke, the bolts rotate together with the connecting rods and their central eccentric cylindrical surfaces in the rod bearings. The rotational movement of the bolt about this second shifted axis leads quasi to the extension of the connecting rods. As a result of this "extension", the connecting rod-rod coupling point does not reach the MT when going down, but reaches 20 ° to the horizontal in EUT when the connecting rods are in position. This will generate the short stroke.

The Hubwechselvorrichtung is shown in the position of the OTs at the end of the exhaust stroke in Fig. 9. At this moment she is prepared for carrying out short stroke. The cam disc ( 1 ) is replaced by the gear wheel ( Fig. 9, numeral 2, Fig. 8, numeral 22) of the crankshaft ( 8 , Fig. 8), the gears ( 4, 5 ), which surround the pin axis ( 3 ) rotate, and by the gear ( 6 ) by means of attached to it shaft ( 7 ) driven. This gear train drives the cam disc with a reduction ratio of 3: 1 relative to the crankshaft. The cam disc ( 1 ) with its two profile channels ( 16 ), in each of which a slider slides from the corresponding pawl, controls and fixes the pawls ( 8 and 12 ) in the engine cycle. Thus, the pawl ( 8 ), whose axis of rotation ( 14 ) is fixed to the rod ( 17 , Fig. 9, also Fig. 2, Fig. 8), from the catch of the toothed sector ( 9 ) with the bolt ( 11 ) attached, brought out to decouple the bolt ( 11 ) from the rod ( 17 ). At the same time, the locking hook ( 12 ), whose axis of rotation is fastened to the connecting rod ( 18 , FIG. 9, also number 5, FIG. 8), engages in the detent of the toothed sector ( 13 ) which is fastened to the bolt ( 15 ) , As a result, the tooth sector ( 13 ) is connected to the connecting rod ( 18 ). By this position, the pin ( 15 ) is rotated in Einsässakt together with the connecting rod ( 18 ) about its axis ( 19 ) relative to the rod ( 17 ) and by the connection of the toothed sector ( 9 ) and ( 13 ) based on their sprockets is synchronized on the same corner also the bolt ( 11 ) turned. The pin fixed in the connecting rod rotates in the bearing of the rod about its displaced axis ( 20 ), which extends the connecting rod in its inclination and virtually reach them to reach the MT, so short-stroke is generated. After the compression stroke, when the piston returns from the EUT back to TDC, both pawls are moved by means of the cam in the original position: The seated on the rod hook ( 8 ) fixed directly to the tooth sector ( 9 ) and immediately the bolt ( 11 ). The tooth sector ( 9 ) fixed by its sprocket tooth sector ( 13 ) with the bolt ( 15 ). In this position, the bolts rotate about their axes ( 20 ), causing no displacement and the piston makes a long stroke.

The correct exit of the connecting rod from the MT is ensured by the mechanism C ( FIGS. 8, 11), which is shown in details in FIG . It consists of guide surfaces ( 2, 3 ) in the housing ( 9 ) of the engine, where the extended connecting rod end ( 8 ) with its sliding slider ( 5 ) comes in. In order to prevent the slider ( 5 ) comes to the wrong guide surfaces at the MT, where the tracks in the working and in the exhaust stroke, the guide surfaces ( 2 ) and ( 3 ) are separated from each other and before and behind the connecting rod ( 6 ) set up. During the power stroke, the slider ( 5 ) in the connecting rod end ( 8 ) by the inclined stop plane ( 7 ) of the motor housing at the entrance to the control zone moves backwards and into the guide surfaces ( 2 ) of the power stroke. In the exhaust stroke, the connecting rod end comes through another input in the control zone and its slider is here by the reverse slope of the stop planes ( 10 ) of the motor housing moved forward, whereby it comes on the guide surfaces ( 3 ) during the exhaust stroke. To avoid erroneous positions of the motor mechanism in the reverse direction of rotation, the guide surfaces are symmetrical, and prevent undefined conditions even when returning the crankshafts.

In the intake stroke, the rod end describes a curve (from point 3 through 4 to point 5) which is very similar to the lower part of its path ( 1 ) in the working cycle (see Fig. 10, 1; Because in these two strokes the connecting rod end ( 8 ) comes into the control zone at the same point and the slide into the guide surfaces of the working stroke, one only has to make sure that the slider is at the point where the tracks separate comes out of the working cycle guide channel and does not prevent the return of the piston from the EUT to the TDC, for which the cutout ( 4 ) is provided in the guide surfaces.

The working cycle of this WHM is almost equal to half of its cycle (44.5%) (see Fig. 3, curve 1). So compared to the conventional four-stroke engines, this change-stroke motor design has a 1.78 times longer cycle in its cycle or 18% longer operating efficiency (assuming the equality of cycles of the WHM and the conventional engine in a given period of time ), which results in smoother running of the motor shaft. All three preparatory operations of the WHM are also cheaper distributed in comparison with a conventional engine. The compression stroke only takes 13% of the cycle. The intake stroke is longer by 1.57 (20.4%), thus enabling a good mixture loading of the cylinder even without an upstream blower. The exhaust stroke lasts 22.2% of the cycle, which is sufficient for an energy-saving exhaust: there are no high throttle losses.

In addition to the increase in performance promises the WHM with the same displacement following increase in efficiency (as a basis, is the compression ratio 10 for the gasoline engine and 22 for the diesel engine adopted):

• 1. by additionally used gas expansion - 19% (gasoline engine) and 11% diesel);
• 2. through better combustion and reduction of heat losses in the power stroke - an estimated 15% (gasoline engine) and 10% diesel);
• 3. By reducing the friction losses between the piston and cylinder walls and allowing the exhaust gases to exhaust more easily, because the final pressure has previously been greatly reduced by the higher expansion - estimated at 5%.
  Overall, relatively: 39% for the gasoline engine and 26% for the diesel engine.

In addition, this embodiment has all the advantages of the above have been called.

Claims (2)

1. Wechselhubmotor is a piston internal combustion engine, characterized by
a mechanism instead of the conventional crank mechanism, the
a crankshaft, with the crank of which a connecting rod is coupled with P <K (P - length of rod, K - crank length),
an intermediate member which is coupled by a pivot to the connecting rod and is connected directly or indirectly, movably or immovably to the piston,
a mechanism A which holds the movements of the connecting rod intermediate coupling point on a path determined by the mechanism A,
a mechanism B that alternately performs two procedures according to a given program:

• 1) It ensures that the tangent of the path of the connecting rod-link coupling point is perpendicular to the connecting rod when the angle between the connecting rod and the crank is 0, and that the connecting rod-linkage coupling point its direction of movement at this point does not change.
• 2) Case A: It ensures that the tangent of the path of the connecting rod-linkage coupling point is not perpendicular to the connecting rod when the angle between the connecting rod and the crank is zero.
  Case B: It causes the rod-linkage coupling point to change its direction of travel when the angle between the connecting rod and the crank is 0 and the tangent of the path of the connecting rod-linkage coupling point is perpendicular to the connecting rod.

and
a mechanism C which inhibits movement direction changes of the connecting rod-link coupling point not generated by the mechanism B and random changes of direction of rotation of the crankshaft,
contains.