WO2014121874A1

WO2014121874A1 - Asymmetric reciprocating piston compressor

Info

Publication number: WO2014121874A1
Application number: PCT/EP2013/077044
Authority: WO
Inventors: Christopher Zaum; Rainer Detering
Original assignee: Continental Reifen Deutschland Gmbh
Priority date: 2013-02-05
Filing date: 2013-12-18
Publication date: 2014-08-14
Also published as: EP2954208A1; CN104981609A; CN104981609B; DE102013101110A1; EP2954208B1; PL2954208T3

Abstract

The invention relates to a reciprocating piston compressor having a piston that is driven by way of a slider-crank mechanism and can be moved back and forth in a cylinder and is sealed with respect to the cylinder wall, which is arranged in a fixed manner to the connection rod axis. The piston and/or the cylinder are configured such that the sickle-shaped gaps between piston edge and cylinder wall formed during the compression stroke due to the relative inclination or tilt between piston and cylinder axis can be sealed, and leakages can be offset in this way.

Description

description

Asymmetric reciprocating compressor

The invention relates to a reciprocating compressor, in particular a

A reciprocating compressor for a portable small compressor unit, with a driven by a crank and a reciprocally movable in a cylinder and sealed against the cylinder wall piston, said crank drive having a arranged on a crankshaft crank wheel with an eccentric crank pin and a between the piston and the Crank pin arranged connecting rod, wherein the piston or piston crown is arranged fixed to the connecting rod.

Such reciprocating compressors are usually made of small fast-rotating

Electric motors powered by a pinion on their output shaft in one

engage corresponding external toothing of the crank wheel. Small compressor units are often required for so-called "breakdown kits", i.e. for breakdown assistance systems, in particular for temporarily sealing and re-inflating automotive tires after air loss

Switching usable, such as the use of the compressor alone when inflating air mattresses or rubber boats. Both in the production and in the assembly of such small but fast-running compressors as little effort as possible and thus costly production methods and materials are avoided, which often leads to the use of simple and lightweight plastics for all sorts of components, including the piston. In these air compressors usually a rotationally symmetrical piston is used in a rotationally symmetrical cylinder. To reduce costs in these Systems dispensed with a piston joint and the piston rigidly connected to a crankshaft via a connecting rod. In a right-angled connection between piston and connecting rod, the highest sealing capability between piston and cylinder in the dead centers, ie in the ends of the range of movement of the piston (top dead center = OT / lower

Dead center = UT). In the middle of the range of motion, the sealing ability decreases, as by a deviation of the axis of symmetry of the piston from the axis of symmetry of the cylinder, the so-called piston pitch is pronounced and no optimal concern of the piston seal on the cylinder wall is given more. While the piston inclination during idle stroke is only problematic when the reciprocating compressor works with a form, it is very disadvantageous in the compression stroke, since the maximum sealability should be achieved here for the most efficient operation of the compressor. The use of a particularly flexible piston seal solves the problem only insufficient, since such a highly flexible seal while the lowering of the sealing ability slightly reduced, but does not prevent the basic reduction of the sealability in the middle range of movement of the compression stroke and thus does not delay the time of maximum or minimum sealing ability , Even at low temperatures such a piston seal is no longer suitable to prevent the decrease in the sealing ability, since then the piston seal hardens.

To remedy this situation, DE 20 2011 052 002 Ul discloses an air compressor in the form of a reciprocating compressor, in which the piston and thus the upper

Piston bottom inclined to the connecting rod axis and in the dead centers also considered to

Cylinder axis is formed inclined and top dead center (TDC) with a

Complementarily inclined head surface of the cylinder cooperates. This leads to an appropriate design to the fact that during the compression stroke of the piston with substantially perpendicular to the cylinder wall piston bottom moves and thus effectively compressed, while the idle stroke of the piston with increased inclination is shifted to the cylinder wall and thus ambient air can flow very easily past the piston seal in the compression space.

The disadvantage here is the costly production of pistons with connecting rods and cylinders and the required tilt-correct mounting of the piston. For example, the cylinder base, or the inside of the cylinder head must also be formed inclined so that sufficient compression takes place and thus the inclined piston does not abut the cylinder head in TDC and is damaged. Based on this, the object of the invention to provide a reciprocating compressor, especially for a high-speed small compressor within portable / portable devices, which in spite of simple production without piston joint and despite the use of inexpensive materials, a high compression ratio and a high delivery volume even with a kinematic inevitable

Piston tilt reached and avoids leaks during the lifting movement.

This object is achieved by the features of the main claim. Further advantageous embodiments are disclosed in the subclaims. In this case, the piston and / or the cylinder are formed so that during the respective stroke movement by the relative inclination between the piston axis and

Cylinder axis resulting sickle-shaped gaps between piston edge and

Cylinder wall are sealable. If a piston in a cylinder is movable about several axes, there is an orientation of the piston to the cylinder due to the ratio of the piston shape to the cylinder shape, in which a maximum sealing capability between the piston and cylinder is provided via the piston seal. This is the case in TDC and also in BDC when piston axis and cylinder axis substantially coincide. If this alignment with maximum sealing capability can not be maintained over the entire range of motion of the piston, a periodic piston movement will also result in a periodic change the sealing ability between piston and cylinder. During the movement of the piston through the middle range of motion caused by the piston tilt sickle-shaped gaps between the piston wall and the cylinder wall. The invention solves this problem in that the piston, here also understood as a complete assembly with piston seal, and / or the cylinder by their geometric or material engineering training or accessories seal the crescent-shaped column. The inventive training a performance increase of up to 20% over prior art devices could be achieved.

A particularly advantageous, because in the simplest way to be produced training is that the piston or piston crown is arranged perpendicular to the connecting rod

Another particularly advantageous embodiment is that the piston has a deviating from the circular shape oval-elliptical shape through which the crescent-shaped

Column are at least partially compensated, wherein the piston is designed so that about elastically yielding, compressible or geometrically flexible, that during the entire stroke and in the dead points an elastic seal between the piston and cylinder wall, of course, especially with the help of elastic or compressible trained annular piston seal. This achieves not only an improved seal during the compression stroke in the middle by a simple static-geometric change of the piston shape or contour

Movement range, thus a higher compression ratio and also a larger delivery volume, but also a secure seal during the entire idle stroke.

Compared to the known solutions of the prior art, here for example compared to the fixed and inclined to the connecting rod axis formed piston crown in DE 20 2011 052 002 Ul, the solution according to the invention thus also has the advantage that by existing even during idle safe seal of the

Reciprocating compressor can also be followed by a supercharger, so with already pre-compressed charge air can be applied. This significantly increases the compression ratio again.

The piston according to the invention is of course designed with its deviating from the circular shape oval elliptical shape so that the large semi-axis is perpendicular or substantially perpendicular to the shaft of the crank wheel.

A further advantageous embodiment is that the piston has an oval-elliptical shape, wherein the length of the semi-minor axis is at least 80% of the length of the major half-axis. This is a confirmed by experiments training in which on the one hand sufficient sealing force during the lifting movement is present and on the other hand, the friction assumes no harmful sizes in the dead centers.

In such an inventive design of small compressors, z. For example, for a portable breakdown assistance system, such a design advantageously consists in that the piston has an oval-elliptical shape, the small semi-axis I \ mm and the semi-major axis have a length of I \ mm. Surprisingly, even such a small ellipticity of the piston improves with one

Half-axis difference of only 0.2 mm the compression ratio and the

Funding volume considerably.

A further advantageous embodiment is that the piston has a circular shape and the annular piston seal has a varying thickness, in which the

Thickness maximum is arranged and formed so that the crescent-shaped gaps are compensated, wherein the piston seal is formed so that during the

Compression and in the dead points, an elastic seal between the piston and the cylinder wall takes place. Thus, the piston itself does not need to be changed, which allows the use of normal standard piston, but only the thickness of the annular

Piston seal to make simple static-geometric change of the effective

sealed area of the piston to achieve the compression ratio and Delivery volume improved.

A further advantageous embodiment is that the cylinder has in its central compression region a deviating from the circular shape oval-elliptical shape through which the crescent-shaped gaps are at least partially compensated, wherein the annular piston seal is formed so that during the entire lifting movement and in the dead center is an elastic seal between the piston and cylinder wall. The required additional processing cost of the cylinder is acceptable in particular for cast cylinders, if for the usually made of plastic piston can be used as cheap standard parts and the cylinder is possibly reusable.

A further advantageous embodiment is that the compensation of the

Crescent-shaped column on the piston and / or on the seal by adjusting elements on the piston takes place, in particular by resilient elements or by elements which are acted upon by a pressure medium. In contrast to the use of a highly flexible piston seal here the adjustment takes place dynamically and directionally depending on the design of the crescent-shaped gap between the cylinder and piston contour by constructive measures or additional construction elements. This procedure allows u.a. Achieving the maximum sealability at more than one time of the periodic piston movement.

A further advantageous embodiment is that the resilient elements are arranged in the piston body, in particular by means of resilient circumferential webs which are arranged concavely over a partial circumference of the piston through to the piston center

kidney-shaped recesses are formed

A further advantageous embodiment is that the compensation of the

Crescent-shaped column on the piston and / or on the seal inserted through

Form elements (intermediate elements) takes place. Here lies the advantage that only in the Regions of the piston circumference in which the gaps arise, additional elements are introduced, the z. B. spread the seal accordingly or press it resiliently.

Since with the invention, a reciprocating compressor is formed, which has very high pressure and flow rates with the simplest design even for small sizes, such a reciprocating compressor, as already said, is particularly suitable for a portable

Pannenhilfesystems for sealing and inflating inflatable objects, in particular of tires, wherein the breakdown assistance system comprises a container for a fillable in the inflatable object automatic sealing means, a valve and

Distributor unit for sealing means and compressed gas and connecting means between valve and distributor unit and inflatable object, means for supplying energy and switching and / or control means for the operation of the system and is equipped with a compressed gas source in the form of a compressor. Reference to an embodiment, the innovation will be explained in detail. Show it

Fig. 1 is a schematic diagram of a reciprocating compressor according to the invention

Fig. 2 is a production drawing of a piston for

Hubkolbenverdichter invention.

Fig. 1 shows in the form of a schematic diagram of a reciprocating compressor 1 of a portable breakdown assistance system for sealing and inflating tires with a driven via a sliding crank and a cylinder 2 back and forth and sealed against the cylinder wall piston 3, wherein the sliding crank drive a Arranged on a crankshaft crank 4 with an eccentric crank pin 5 and arranged between the piston 3 and the crank pin 5 connecting rod 6, wherein the piston 3 and the piston head 7 is arranged fixed perpendicular to the connecting rod 8, so that the connecting rod 8 and piston axis. 9 to match. The right part of Fig. 1 shows the reciprocating compressor 1 with its piston 3 in TDC, the left part of the reciprocating compressor 1 with its piston 3 during the compression stroke. In the existing here rigid connection between the piston and connecting rod without

Piston joint is the highest sealing capability between the piston and cylinder in the TDC and UT reached, as shown on the right side of FIG. 1 in the TDC. Normally, in the middle of the range of motion, the sealing ability decreases, as by deviating the symmetry axis of the piston, i. in this case, the connecting rod and piston axis 8, 9 from the axis of symmetry of the cylinder 10, the so-called

Piston inclination is pronounced and no optimal concern of the piston seal on the cylinder wall is given more.

In the case of the reciprocating compressor 1 shown in FIG. 1, this is not the case, since the piston, understood here as an entire subassembly with piston seal, is designed such that it is shown during the on the left side of FIG

Kompressionshubs by the relative inclination between the piston axis and cylinder axis resulting sickle-shaped gaps 11, 12 between the piston edge and cylinder wall are sealable, namely the fact that the piston 3 and thus the piston head 7 has a deviating from the circular shape oval-elliptical shape through which the

Crescent-shaped column are at least partially compensated. The projection 7a of the inclined piston crown 7 in the lower left part of Fig. 1 shows this by the representation of the deviations I Ia and 12 a of the piston crown 7 of the ideal

Kreisforml3. The large semi-axis 14 of the oval-elliptical piston crown has a

32 1 \ 31 7 \

Length of I \ mm and the small half-axis 15 a length of I \ mm.

The annular piston seal not shown here is so compressible and geometrically flexible, that during the entire stroke and in the dead center, a secure elastic seal between the piston and the cylinder wall. Of course, the seal in OT and UT is then compressed and deformed more than in the middle compression range. 2 shows a production drawing of a piston 3 for a reciprocating compressor according to the invention in a sectional view and in a plan view with one of the Circular shape deviating oval-elliptical shape, wherein the diameter X is twice the large half-axis 14 and the diameter Y is twice the small half-axis 15, here X = 32.1mm and Y = 31.7mm.

The piston is provided with kidney-shaped recesses 16 and 17, which give the piston in the region of the large half-axes sufficient flexibility by serving as resilient elements peripheral webs 18 and 19, so that the piston can approach in TDC and UT to the ideal circular shape ,

The compensation of the crescent-shaped column takes place here so by resilient elements on the piston, wherein the resilient elements are formed in the piston body, here by means of resilient peripheral webs 18, 19, which are formed by concave to the center of the piston down kidney-shaped recesses 16, 17, wherein webs and

Recesses are arranged in the region of the major half-axes over a partial circumference of the piston 3.

LIST OF REFERENCE NUMBERS

(Part of the description)

1 reciprocating compressor

2 cylinders

3 pistons

4 crank wheel

5 crankpins

6 connecting rods

7 piston bottom

7a projection of the inclined piston crown

8 connecting rod axle

9 piston axis

10 symmetry axis of the cylinder

11 Crescent-shaped gap

I Ia deviation from the circular shape

12 Crescent-shaped gap

12a deviation from the circular shape

13 Ideal circular shape

14 big half-axle

15 small half-axle

16 Kidney-shaped recess

17 Kidney-shaped recess

18 peripheral ridge

19 peripheral ridge

Claims

Patent claims

Reciprocating compressor (1) with a slider crank drive and

one that can be moved back and forth in a cylinder (2) and opposite the

Cylinder wall sealed piston (3), the sliding crank drive having a crank wheel (4) arranged on a crankshaft with an eccentric crank pin (5) and a connecting rod (6) arranged between the piston (3) and the crank pin (5), the piston (3) or piston crown (7) is arranged fixed to the connecting rod axis (8), characterized in that the piston (3) and / or the cylinder

(2) are designed in such a way that the crescent-shaped gaps (11, 12) created between the piston edge and the cylinder wall during the respective stroke movement due to the relative inclination between the piston axis (9) and cylinder axis (10) can be sealed.

Reciprocating piston compressor according to claim 1, in which the piston (3) or piston crown (7) is arranged perpendicular to the connecting rod axis (8).

Reciprocating piston compressor according to claim 1 or 2, in which the piston

(3) has an oval-elliptical shape that deviates from the circular shape, through which the crescent-shaped gaps (11, 12) can be at least partially compensated, the piston being designed in such a way that an elastic seal is formed between the piston and the piston during the lifting movement and in the dead centers Cylinder wall takes place.

4. Reciprocating piston compressor according to claim 3, in which the piston (3) has an oval-elliptical shape in which the length of the minor semi-axis (15) is at least 80% of the length of the major semi-axis (14).

5. Reciprocating piston compressor according to claim 3 or 4, in which the piston (3) has an oval-elliptical shape, the major semi-axis (14) of which has a length of I - - I mm and whose small semi-axis (15) has a length of mm.

6. Reciprocating piston compressor according to one of claims 1 to 5, in which the piston (3) has a circular shape and the annular piston seal has a varying thickness, in which the maximum thickness is arranged and designed so that the crescent-shaped gaps (11, 12) can be compensated , so that there is an elastic seal between the piston and the cylinder wall during the entire stroke movement and in the dead centers.

7. Reciprocating piston compressor according to one of claims 1 to 6, in which the cylinder in

its middle compression area has an oval-elliptical shape that deviates from the circular shape, through which the crescent-shaped gaps (11, 12) can be at least partially compensated for, so that an elastic seal occurs between the piston and the cylinder wall during the entire stroke movement and in the dead centers

8. Reciprocating piston compressor according to one of claims 1 to 7, in which the sickle-shaped gaps (11, 12) on the piston and/or on the seal are compensated for by resilient elements (18, 19).

9. Reciprocating piston compressor according to claim 8, in which the resilient elements in

Piston bodies are formed, in particular by means of resilient circumferential webs (18, 19), which are formed over a partial circumference of the piston (3) by kidney-shaped recesses (16, 17) arranged concavely towards the center of the piston.

10. Reciprocating piston compressor according to one of claims 1 to 9, in which the compensation of the sickle-shaped gaps (11, 12) on the piston and / or on the seal takes place by adjusting elements, in particular by elements which are acted upon by a pressure medium.

11. Reciprocating piston compressor according to one of claims 1 to 10, in which the compensation of the crescent-shaped gap (11, 12) on the piston and / or on the seal is carried out used form elements takes place.

12. Portable breakdown assistance system for sealing and inflating inflatable objects, in particular tires, the breakdown assistance system comprising a container for an automatic sealant which can be filled into the inflatable object, a valve and distributor unit for sealant and compressed gas and connecting means between the valve and distributor unit and the inflatable object , means for supplying energy as well as switching and / or control devices for the operation of the system and is equipped with a compressed gas source in the form of a compressor, designed as a reciprocating compressor according to one of claims 1 to 11.