DE102011003795A1 - Flow control - Google Patents

Abstract

A reciprocating piston machine with continuously adjustable delivery volume is described, comprising a piston (KO), a split connecting rod (1) engaging it with a lower and an upper connecting rod (2, 3) and an arm (4), the upper connecting rod (3 ) acts on a cross head (KK) of the piston (KO) and on the link (4), the lower connecting rod (2) connects the link (4) with a crank pin (B) of a crankshaft (KW) and the link (4) at its end opposite the connecting rods (2, 3) has a support (E) which cooperates with an adjusting mechanism (5). The invention was based on the object of providing a reciprocating piston machine with a stepless volume flow control while maintaining the specified installation space. The object is achieved according to the invention with a reciprocating piston engine in the form of a compressor, which has first and second compression chambers (6, 7) separated by the piston (KO), and the support (E) via the adjusting mechanism (5) between a position of the maximum nominal stroke (Hmax) and a reduced stroke (Hmin) is adjustable on at least one section of a predetermined isoline of constant crosshead central position.

Description

The invention relates to a reciprocating engine according to the features standing in the preamble of claim 1.

Such reciprocating engines come in a structurally different design, for example as internal combustion engines or as a compressor used.

A generic state of the art is the DE 30 30 615 A1 , The known document discloses an internal combustion engine with at least one cylinder and a reciprocating piston therein, which is connected via a linkage with a crankshaft. The linkage comprises a hinged to the piston first connecting rod, a hinged to the crankshaft second connecting rod and a pivot lever which is articulated at one end about a crankshaft axis substantially parallel pivot axis and hingedly connected at its other end to the two connecting rods. The articulation point of the pivot lever should be arranged radially and / or axially adjustable and, for example, on a rotatably mounted eccentric. With the help of the known linkage, the course of the torque transmitted from the piston to the crankshaft and the course of the piston speed should be varied to a large extent.

However, a transfer of knowledge gained from internal combustion engines to compressors has not led to satisfactory results. In particular, no continuous volume flow control can be realized with the known features.

Accordingly, the invention has for its object to provide a reciprocating engine with a continuous flow control while maintaining the predetermined space.

The object is achieved according to the invention with a reciprocating piston engine in the form of a compressor having first and second compression chambers separated by the piston, and the support via the actuating mechanism between a position of the maximum nominal stroke and a reduced stroke on at least a portion of a predetermined constant cross-section Center position is adjustable. The isoline represents a trajectory for the support.

The reciprocating piston engine according to the invention thus allows a continuous regulation of the delivery volume while maintaining the existing installation space with comparatively low construction costs. The crosshead center position is understood to mean a position of the piston corresponding to its half stroke.

The link eliminates an additional degree of freedom of the crank mechanism and determines with its bearing point the stroke of the piston and the crosshead center position. In an adjustment of the armature and concomitant reduction in the piston stroke, if the adjustment takes place at a constant crosshead center position, the dead space on both sides increased by the same amount, that is, the piston no longer performs the maximum Nennhub, but only a reduced Hub within the cylinder. In this case, compliance with the crosshead center position is of great importance, since otherwise the dead space is not changed by the same amount on both sides of the piston. Experience has shown that a larger flywheel is therefore necessary in such devices. In addition, the load change characteristics of the crosshead bearing pin is adversely affected in different sized dead zones and it is also to be assumed by an increased inducing harmonic oscillations in subsequent gas chambers and caused by an increased tendency to resonance formation.

Conveniently, the support comprises a linkage bearing, with which the linkage member rotatably engages the support.

Advantageously, the upper connecting rod, the lower connecting rod and the Anlenker form a ternary joint. At the ternary joint both the upper and lower connecting rods and the link arms rotate in a common point or a common bearing axis. The essential advantage of this embodiment is that in the support of the armature the lowest expected Anlenkerkraft occurs.

A trained with the ternary joint compressor can be designed for example on the basis of a numerical solution. In this case, first of all a rectangular area is defined, which comprises the area suitable for accommodating the articulated arm support E (installation space condition). This rectangular area is then provided with a screening, wherein the points of the grid correspond to the respective position of the armature support E.

und

mit x_KWE = x_E – x_KW, y_KWE = y_E – y_KW, l_KWE ² = x_KWE ² + y_KWE ² und k₁ ∊ {–1; 1} und

berechenbar ist, wobei sich der jeweilige obere und untere Totpunkt (OT, UT) aus

mit k₂ ∊ {–1; 1} ergibt und die Kreuzkopf-Mittellage (y_KK,Mittel) durch Einsetzen in die Gleichung

definiert ist.Then, for each of these grid points, the dead-center of the four-joint KW-BCE can be identified. These are given in the extended position or cover layer of crank and lower connecting rod according to

and

with x _KWE = x _E - x _KW , y _KWE = y _E - y _KW , l _KWE ² = x _KWE ² + y _KWE ² and k ₁ ε {-1; 1} and

is calculable, with the respective top and bottom dead center (OT, UT) of

with k ₂ ε {-1; 1} and the crosshead center position (y _{KK, mean} ) by inserting into the equation

is defined.

The calculations are geometrically interpretable: The position of the joint C in the dead centers follows from the intersection of the circumcircle with the radius l _T = l ₂ ± r _K around the crankshaft and the circumcircle with the radius l ₄ around the support E. The position of the Joint D with the coordinates x _KK / y _KK follows from the intersection between the radius of radius l ₃ and C with the output axis. The determination of one of the two intersections generated in this way is done via the position parameters k ₁ and k ₂ .

Preferably, the bearing axis of the arranged between the upper connecting rod and crosshead piston-side connecting rod bearing, the bearing axis of the arranged between the lower connecting rod and crank pin crankshaft side connecting rod bearing, the bearing axis of a ternary joint and the bearing axis of a Anlenker bearing are arranged parallel to each other. Consequently, it is with the inventive arrangement of the bearings to a flat gear.

und

mit x_KWE = x_E – x_KW, y_KWE = y_E – y_KW, l_KWE ² = x_KWE ² + y_KWE ² bei

berechenbar ist, wobei sich der jeweilige obere und untere Totpunkt (OT, UT) aus

mit k₂ ∊ {–1; 1} ergibt und die Kreuzkopf-Mittellage (y_KK,Mittel) durch Einsetzen in die Gleichung

definiert ist.According to an alternative embodiment, the lower connecting rod and the upper connecting rod engage at spaced bearing points of a ternary Anlenkers. The ternary Anlenker thus has three bearings, which form a triangle to each other, wherein a first bearing point with the support, a second bearing point with the lower connecting rod and a third bearing point is connected to the upper connecting rod. The determination of the dead-spots can be carried out according to the aforementioned embodiment, wherein

and

with x _KWE = x _E - x _KW , y _KWE = y _E - y _KW , l _KWE ² = x _KWE ² + y _KWE ² at

is calculable, with the respective top and bottom dead center (OT, UT) of

with k ₂ ε {-1; 1} and the crosshead center position (y _{KK, mean} ) by inserting into the equation

is defined.

Preferably, it is checked before determining the crosshead center position, whether the link (reference numerals of the description of the figures 4 , or in ternary Anlenker 42 ) occupies itself during the movement between the stretch or cover layer of the crank and lower connecting rod itself a stretch or cover layer with the upper connecting rod. If this is not the case, the layers from the above-exemplified calculation also describe the dead spots of the crosshead. Otherwise, a crosshead dead center is due to the extended position of the armature ( 4 , or in ternary Anlenker 42 ) and the upper connecting rod, and the other is given by one of the layers from the above calculation.

In further embodiments, the lower connecting rod or the upper connecting rod may be formed in each case as a ternary connecting rod.

In a particularly favorable embodiment, the positioning mechanism comprises a linear guide with a stationarily arranged rail and a slidably engaging carriage, wherein the support is arranged on the carriage and the orientation of the adjusting mechanism is approximated to approximate the portion of an isoline of the constant crosshead center position. This embodiment represents a technically simple implementation of the teaching according to the invention, the accuracy of which is sufficient for operation in practice. The adjusting mechanism or the associated linear guide is already aligned in the production of the compressor according to the known coordinates of the isoline and fixedly mounted on the compressor.

On the carriage can engage a linear drive whose adjustment is aligned parallel to the axial extent of the rail. As a linear drive in particular form-locking lockable elements, racks can be used with complementarily arranged on the carriage gears or threaded spindles used. According to a particularly advantageous embodiment, the linear drive comprises a Hydraulic cylinder, which is held stationary with a first end and secured with its second, opposite end to the carriage.

Conveniently, the linear guide is oriented at an angle (α) between 0 ° and 45 ° inclined to the axis of movement of the piston.

For a better understanding of the invention will be explained below with reference to a total of six figures. The show

1 a schematic view of a compressor according to the invention according to a first embodiment;

2 a schematic view of a compressor according to the invention according to a second embodiment;

3 : Calculation of isolines by line-following algorithm;

4 a field of isolines of constant central crossheads;

5 a longitudinal section of the compressor according to 1 with linear approximation of the isoline and linear guidance of the support as well

6 : a schematic representation of the compressor according to 5 ,

The 1 shows a schematic view of a reciprocating compressor according to the invention according to a first embodiment with a ternary joint C, to which a connecting rod 1 comprising a lower connecting rod 2 and an upper connecting rod 3 as well as a link 4 attack together. In this case, a crank K formed on a crankshaft KW with its crankpin B and the crankshaft-side connecting rod bearing L _P2 arranged thereon sets a rotational movement corresponding to the crank angle φ of the crankshaft KW via the lower connecting rod 2 and the upper connecting rod 3 in an oscillating linear movement of one end to the upper connecting rod 3 arranged piston KO order. The upper connecting rod 3 engages with a piston-side connecting rod bearing L _P1 at the crosshead KK of the piston KO. The piston KO moves during operation of the compressor within the movement axis 14 ,

The Anlenker 4 extends from the ternary joint C to a side of the axis of movement 14 of piston KO offset armature bearings 4a of a support E.

The spatial position of the crankshaft KW or its centric axis is defined via its coordinates x _KW / y _KW , the position of the crosshead KK via its coordinates x _KK / y _KK and that of the support E via the coordinates x _E / y _E. The illustrated embodiment of the compressor has a so-called centric push crank, in which the extension of the movement axis 14 runs through the crankshaft axis perpendicular to her, the invention is basically also on compressors with eccentric arrangement of the crank handle can be realized.

Dotted in the region of the support E are two intersecting isolines of a maximum nominal stroke H _{max of} the piston KO, wherein in the shown state of the compressor the support E is located on the substantially vertical characteristic of a maximum rated stroke H _{max of} the piston KO. At the maximum rated stroke H _max , the piston KO moves on the movement axis 14 between its top dead center OT and its bottom dead center UT. Between the top and bottom dead center OT, UT is the crosshead center location y _{KK, means} . It remains within the in 1 Not completely shown cylinder or arranged on both sides of the piston KO first and second compression chamber 6 . 7 (please refer 5 ) a minimal dead space. Since it is a compressor with a centrally arranged thrust crank, the x coordinates of the crosshead KK also correspond to the x coordinates of the crankshaft x _KW .

In addition, in the presentation of the 1 with dashed line a family of curves of isolines of constant crosshead center layers y _{KK, means} to detect. According to the teaching of the invention, the support E is to be displaced on an isoline constant crosshead center position and simultaneously moved out of its position of the maximum nominal stroke H _max for an adjustment of the flow of the compressor. By way of example, a position of a reduced stroke H _min on the corresponding isoline is a constant one Phillips middle position Y _{kk, middle} marked. In this position of the support E of the piston KO continues to perform an alternating movement about its central position y _{KK, means} , but at significantly increased dead space in the respective compression chambers 6 . 7 (please refer 5 ) and a reduced stroke and a resulting reduced delivery volume.

For an increase in the delivery volume, the support E is moved from the exemplarily marked position H _min back on the isoline of a constant crosshead center position y _{KK, means} to the point of intersection with the isoline of the maximum nominal stroke H _max . Likewise, an adjustment in each point between H _min and H _{max is} possible.

The 2 shows an alternative embodiment of the compressor with a ternary link instead of a ternary joint C, in which the lower connecting rod 2 at a bearing C1 and the upper connecting rod 3 attack at a bearing C1 spaced bearing C2. The bearing C1 and the support E of the ternary Anlenkers define one side 41 and the bearing C2 and the support E a second side 42 , The bearings C1, C2, E thus form a triangle. Furthermore, the sides adjacent to the support E stretch 41 . 42 the angle τ on.

The adjustment of the delivery volume takes place in this embodiment with a ternary Anlenker by adjusting the support E on a in 2 Not shown isoline (see 1 ) of a constant crosshead center position y _{KK, means} with simultaneous removal of the isoline of a maximum nominal stroke H _max .

For example, the calculation of the isoline of the desired crosshead center location y _{KK, means} may be based on Snyder's line-following algorithm, which is used for a grid section in FIG 3 is shown.

Accordingly, as part of the calculation, the raster is traversed line by line in a first step and the edges of each raster cell are examined for intersections with isolines. Such an intersection exists when a searched iso value lies between the parameter values of the two halftone dots involved.

der y-Koordinate analog. Zusätzlich wird vermerkt, dass der Isowert auf der aktuellen Gitterkante erkannt wurde, damit dieser Schritt nicht wiederholt wird.If such a grating edge has been found, in a second step the intersection P _{section of} the isoline with the edge is determined by linear interpolation of the parameter value w (0 ≦ w ≦ 1) between the start and end points of the edge. The calculation of the x-coordinate takes place after

the y-coordinate analog. In addition, it is noted that the iso value has been recognized on the current grid edge so that this step is not repeated.

Subsequently, in a third step, the grid cell adjacent to the current grid edge, that is to say the edge on which the intersection with an isoline has been found, is examined for another intersection with the current isoline. Once this edge is found, the point of intersection is determined and the two intersection points are connected with a straight line.

The above steps should then be repeated until all of the grid edges intersecting with the sought-for isoline are already marked for them.

In practicable solutions, the four-bar linkage KW-BCE forms a rocker arm, in which the crank rotates and the link swings. Based on the set by Grashof, the permissible positions of the linkage bearing E can be limited for these gear units. The geometric quantities must satisfy the following equation, with the respective lengths in the 1 are shown: (l _KWE = l _max ∧ r _KW + l _KWE > l ₂ + l ₄ ) ∨ (l _KwE ≠ l _max ∧ r _KW + l _max > l _KWE + l ') with l _max ε {l ₂ ; l ₄ } and l 'ε {l ₂ ; l ₄ } \ l _max

This is the case if the distance between the crank axle and the armature support fulfills the following condition: | l ₂ - l ₄ | + r _KW <l _KWE <l ₂ + l ₄ - r _KW

From the condition of the above equation, it is apparent that all valid solutions by armature bearing positions between two circles with the radii corresponding to the upper and lower limits from this above equation around the crankshaft axis, respectively 4 Marked are.

The 4 also shows the relevant for the determination of the crosshead center positions y _{KK, means} relevant parameters, such as the radius of the crankshaft r _K (sometimes also referred to as r _KW ), the length l _{2 of} the lower connecting rod 2 , the length l _{3 of} the upper connecting rod 3 , the length l _{4 of} the armature 4 , which likewise each of the 1 can be removed. The coordinates x _a , y _{a of} the crankshaft axis KW (also denoted by x _KW and y _KW ) corresponding to the origin of the in the 1 . 2 and 6 recognizable coordinate cross and are therefore set to 0.

Consequently, in the case of the underlying compressor with centric push crank, the offset of the crosshead in the x direction corresponding to x _D (also denoted by x _KK ) must also assume the value 0.

In the 5 and 6 is a compressor with a linearly displaceable support E shown. The displacement of the support E takes place by means of an adjusting mechanism 5 in the form of a linear guide 8th , The linear guide 8th includes a rail 9 and a carriage movably guided on it 10 , which carries the support E and steplessly via a linear drive 11 is movable. The in 6 shown adjustment 12 and the orientation of the linear guide 8th are approximated to an isoline of constant crosshead centerlines y _{KK, mean} . The selection of an isoline from the family of curves of isolines takes place in particular in consideration of the available installation space.

As a linear drive 11 Due to its suitability, it is also capable of transmitting large forces and of being able to approach any position of the adjustment path in a stepless manner, in particular a hydraulic cylinder 13 into consideration. The hydraulic cylinder 13 is with its first end 13a stationary on the compressor and with its second end 13b on the sledge 10 attached.

Like in the 6 it can be seen, the rail runs 9 parallel to the dotted line "approximation" and at an angle α to the axis of motion 14 of the piston KO. The relevant isoline of a constant crosshead center location y _{KK, means} deviates in the selected area only in a central convex shaped portion of the "approximation" or the orientation of the rail 9 from.

LIST OF REFERENCE NUMBERS

1

pleuel

2

lower connecting rod

3

upper connecting rod

4

Anlenker

4a

Anlenker camp

5

mechanism

6

first compression chamber

7

second compression chamber

8th

linear guide

9

rail

10

carriage

11

linear actuator

12

Adjustment linear drive

13

hydraulic cylinders

13a

first end of hydraulic cylinder

13b

second end hydraulic cylinder

14

Movement axis piston

41

Side of ternary link between E and C1

42

Side of ternary link between E and C2

B

Crankpin crankshaft

C

ternary joint

C1

Bearing point lower connecting rod / linkage

C2

Bearing point upper connecting rod / linkage

e

In stock

H _max

maximum rated stroke

H _min

reduced stroke

K

crank

KK

Phillips

KO

piston

KW

Crankshaft (crank axle)

l ₂

Length of lower connecting rod

l ₃

Length of upper connecting rod

₄

Length of link

l _KWE

Distance crankshaft to support E

L _P1

piston-side connecting rod bearing

L _P2

crankshaft-side connecting rod bearing

OT

Top Dead Center

UT

bottom dead center

r _K / r _KW

Radius crankshaft

x _A / y _A

Coordinates crankshaft axis (= x _KW / y _KW )

x _D

x-coordinate crosshead (= x _KK )

x _E / y _E

Coordinates of the linkage support

x _KK / y _KK

Coordinates of the crosshead (downforce)

x _KW / y _KW

Coordinates of the driving crankshaft (crank axle)

y _{KK, means}

Phillips-center position

α

Angle approximated isoline / axis of motion piston

φ

crank angle

τ

Angle between pages 41 . 42

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3030615 A1 [0003]

Claims (12)

Reciprocating piston engine with infinitely adjustable delivery volume, comprising a piston (KO), a split connecting rod engaging therewith ( 1 ) with a lower and an upper connecting rod ( 2 . 3 ) as well as a link ( 4 ), the upper connecting rod ( 3 ) on a crosshead (KK) of the piston (KO) and on the link ( 4 ), the lower connecting rod ( 2 ) the linker ( 4 ) with a crank pin (B) connects a crankshaft (kW) and the armature ( 4 ) at its connecting rods ( 2 . 3 ) opposite end has a support (E), which with an actuating mechanism ( 5 ) cooperates, characterized in that the reciprocating piston engine is a compressor, the first and second compression chambers separated by the piston (KO) ( 6 . 7 ), and the support (E) via the actuating mechanism ( 5 ) is adjustable between a position of the maximum rated stroke (H _max ) and a reduced stroke (H _min ) on at least a portion of a predetermined isoline constant cross-head center position. Reciprocating piston engine according to claim 1, characterized in that the support (E) a Anlenker bearing ( 4a ), with which the link ( 4 ) rotatably engages the support (E). Reciprocating piston engine according to claim 1 or 2, characterized in that the lower connecting rod ( 2 ), the upper connecting rod ( 3 ) and the linker ( 4 ) are rotatably connected via a ternary joint (C). Reciprocating piston engine according to claim 3, characterized in that for each by the adjusting mechanism ( 5 ) changeable point of the support (E), the crosshead center position (y _{KK, middle} ) from the identification of the dead positions of the four-joint KW-BCE in the extended position or cover layer of crank (K) and lower connecting rod ( 2 ) according to

and

with x _KWE = x _E - x _KW , y _KWE = y _E - y _KW , l _KWE ² = x _KWE ² + y _KWE ² , at

is calculable, with the respective top and bottom dead center (OT, UT) of

with k ₂ ε {-1; 1} and the crosshead center position (y _{KK, mean} ) by inserting into the equation

is defined. Reciprocating piston engine according to claim 3 or 4, characterized in that the bearing axis of the upper connecting rod ( 3 ) and crosshead (KK) arranged piston-side connecting rod bearing (L _P1 ), the bearing axis of the lower connecting rod ( 2 ) and crank pin (B) arranged crankshaft-side connecting rod bearing (L _P2 ), the bearing axis of the ternary joint (C) and the bearing axis of the armature bearing ( 4a ) are arranged parallel to each other. Reciprocating piston engine according to claim 1 or 2, characterized in that the lower connecting rod ( 2 ) and the upper connecting rod ( 3 ) at spaced bearing points (C1, C2) of the ternary Anlenkers ( 4 attack). Reciprocating piston engine according to claim 6, characterized in that for each by the adjusting mechanism ( 5 ) changeable point of the support (E) the crosshead center position (y _{KK, middle} ) from the identification of the dead positions of the four-joint KW-B-C1-E in the extended position or cover layer of crank (K) and lower connecting rod ( 2 ) according to

and

with x _KWE = x _E - x _KW , y _KWE = y _E - y _KW , l _KWE ² = x _KWE ² + y _KWE ² at

is calculable, with the respective top and bottom dead center (OT, UT) of

with k ₂ ε {-1; 1} and the crosshead center position (y _{KK, mean} ) by inserting into the equation

is defined. Reciprocating piston engine according to claim 6 or 7, characterized in that the bearing axis of the upper connecting rod ( 3 ) and crosshead (KK) arranged piston-side connecting rod bearing (L _P1 ), the bearing axis of the lower connecting rod ( 2 ) and crankpin (B) arranged crankshaft-side connecting rod bearing (L _P2 ), the bearing axis of the lower connecting rod ( 2 ) and Anlenker ( 4 ) arranged bearing point (C1) and between the upper connecting rod ( 3 ) and Anlenker ( 4 ) arranged bearing point (C2) and the bearing axis of a Anlenker bearing ( 4a ) are arranged parallel to each other. Reciprocating piston engine according to one of claims 1 to 8, characterized in that the adjusting mechanism ( 5 ) a linear guide ( 8th ) with a stationary rail ( 9 ) and an attacking carriage ( 10 ), wherein the support (E) on the carriage ( 10 ) and the orientation of the actuating mechanism ( 5 ) is approximated to the section of an isoline of constant crosshead center position (y _{KK, mean} ). Reciprocating piston engine according to claim 9, characterized in that on the carriage ( 10 ) a linear drive ( 11 ) attacks whose Verstellweg ( 12 ) parallel to the axial extent of the rail ( 9 ) is aligned. Reciprocating piston engine according to claim 10, characterized in that the linear drive ( 11 ) a hydraulic cylinder ( 13 ) having a first end ( 13a ) and with its second, opposite end ( 13b ) on the carriage ( 10 ) is attached. Reciprocating piston engine according to one of claims 9 to 11, characterized in that the linear guide ( 8th ) with an angle (α) between 0 ° and 45 ° inclined to the movement axis ( 14 ) of the piston (KO) is aligned.

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