EP0390882A1

EP0390882A1 - Reciprocating piston engine.

Info

Publication number: EP0390882A1
Application number: EP19890909535
Authority: EP
Inventors: Willi Ernst Salzmann
Original assignee: Individual
Current assignee: Salzmann Willy Ernst
Priority date: 1988-09-07
Filing date: 1989-09-07
Publication date: 1990-10-10
Anticipated expiration: 2009-09-07
Also published as: AU4075489A; DE58909682D1; EP0390882B1; WO1990002867A1; JPH03501044A; ATE138154T1

Abstract

A reciprocating piston engine with a cylinder crankcase (5) with curved cylinder walls (4) and a circular internal cross-section has a reciprocating piston (7) with integrated connecting rod shaft (8) and a circular connecting rod eye (9) which acts as a counterweight. This allows the centre (1) of the piston to trace curves of given shape, which results in a floating movement of the reciprocating piston (7) with very small lateral forces. The larger lateral amplitudes which result require special sealing strips (14) with corresponding pressure springs (15).

Description

Pendulum piston machine

The present invention relates to an improvement on a pendulum kol benmaschi ne. Such a pendulum piston machine is known for example from WO 88/06675. The machine has at least one pendulum piston fixed to a connecting rod, the edge of which runs in a preferably curved cylinder.

In the aforementioned publication WO 88/06675 (Salzmann), it was assumed that, thanks to the counterweight according to the invention, which is arranged below the connecting rod, the center of the piston moves in a straight line and the piston thus moves in the cylinder without any lateral forces. This view was represented on the basis of model tests, in which this impression was created despite stroboscopic lighting. As later mathematical investigations and tests with larger models undoubtedly showed, very small deviations from the straight line are inevitable. The engine designer must therefore live with the condition of a fine piston oscillation in the transverse direction of its movement. Measurements have shown that accelerations in the area of the cylinder head, caused by lateral vibrations, reach values in the range of 20-30 g.

It is consequently the object of the present invention to improve the design of the pendulum piston ben aschi ne in such a way that the unavoidable lateral mass acceleration that occurs occurs as little as possible, the remaining lateral displacement of the piston by corresponding design of the sealing elements of the displacements can pick up and guide the piston. Because of the described lateral displacement, the displacement path of the sealing elements is considerably greater than in known piston machines, in which the sealing elements only have to be displaced in the region of slight play and the additional wear that occurs.

This task is solved by a pendulum piston machine with the characterizing features of claim 1. Further advantages according to the invention result from the dependent claims. Sayings and are explained in the following description. Some exemplary embodiments are outlined in the attached drawing. It shows:

Fig. La-d) different movement curves of the piston center in five times the lateral movements;

2, 2a and 3 a small single-cylinder bicycle auxiliary engine in. Cross and longitudinal section with a detail representation of the piston guide and sealing elements;

4 and 5 a small in-line engine in cross and longitudinal section

6 and 7 show piston guide uncT di chtel elements to the engine of Figures 4 and 5 in plan;

FIG. 8 shows an enlarged detail of the piston guide and sealing element according to FIGS. 7 and

9 and 10 a simplified, fixed on a connecting rod pendulum piston in partial cross-section and horizontal section.

FIG. 1 a shows the movement curve of the piston center 1, the lateral displacement being shown in a five-fold increase. The top dead center is designated 2, the bottom dead center 3. The cylinder walls 4 are curved for geometric reasons so that the distance between the face seals remains constant during the course of the movement. In the case of favorable ratios between the piston length and the piston stroke, the elongated figure-of-eight curve results, which is traversed when the crankshaft runs clockwise according to the arrows. The maximum horizontal amplitude of this curve is approximately 0.8% of the piston stroke and is therefore very small. The curve according to FIG. 1a is described from the center of a piston, the end seals of which do not move relative to the piston. On the other hand, FIG. 1b shows the trajectory of the center of a pendulum, the end seals of which are freely movable relative to the piston. This curve corresponds to an abstraction in gravity-free space. The elongated figure eight according to FIG. 1b is achieved with an optimal counterweight and shows the cam path of the piston center 1 above the piston stroke with the unguided, freely movable pendulum piston ben. It was determined mathematically and experimentally, and it was shown that it In the opposite sense, the curve is traversed as the essentially slender figure-eight curve according to FIG. A smaller increase in the counterweight results in an asymmetrical figure-eight curve according to FIG. 1c, with the advantage that the oscillation amplitude of the piston center point 1 is small in the lateral direction in the region of the upper piston dead center. Therefore, the sealing strips, which are under high gas pressure, only have to shift slightly on their base. These displacements of the face seals mean that coking is impossible. The curve according to FIG. 1d is created when the counterweight is increased somewhat. If the counterweight is successively reduced from the value according to FIG. 1b, the trajectory curves according to FIGS. 1c and d arise, but upside down.

The cylinder crankcase 5 according to FIGS. 2 and 3 has curved cylinder walls 4 which connect to an internally circular crankcase 6. In it runs the pendulum piston 7, which is rectangular in cross section, with an integrated connecting rod shaft 8 and a circular connecting rod eye 9. This is articulated on the crank pin 10 and is so large in diameter that it acts as an optimal counterweight. This is amazing Licher possible because firstly, the lower half of the connecting rod eye 9 acts twice as strongly as the upper half on the reduction of the lateral movement of the piston center 1, and because secondly, the connecting rod shaft 8 is hollow and therefore light. In the case of a unit 7-9 intended as a straight rod (pendulum olben - connecting rod shaft - counterweight), one rod end runs through the movement curve according to FIG. 1b if the length of the counterweight is exactly one third of the rod length. The unit 7-9 can be cast or forged from two half parts which abut one another in the pendulum plane 11 or the normal plane 12 and are connected to one another.

In the front grooves of the pendulum piston 7, the sealing strips 14 are slidably mounted and connected to one another by compression springs 15. These springs 15 are axially displaceably mounted in the longitudinal bores of the pendulum piston and cause the sealing strips 14 to bear continuously against the cylinder walls 4. Shorter compression springs 16 are supported in the blind holes of the pendulum piston, which reach only approximately to the center of the piston, and are supported in their bases and serve to center the piston laterally within the cylinder walls 4 Spring detection and pretensioning ensure that the pendulum piston runs safely and with as little friction as possible, the center point 1 of which, as the speed increases, runs on movement curves between Fig.la to approximately Fig. 1b. Two or more helical springs 15 and / or 16 can be arranged coaxially one inside the other or can be replaced by other elastic means.

The housing 5 is machined from the front. After disassembly of the inner flat front cover 17, the only two movable main parts of the engine, namely the unit 7-9 and the crankshaft 18 with counterweight 19 mounted on both sides of the friction roller 20, are easily accessible.

From the oblique carburetor nozzle 21, the mixture reaches the. Inner circular-cylindrical crankcase 6, in which the unit 7 to 9 runs with little axial and radial play and thus forms a vol umetri see loader, which works the elasticity and power density in two-stroke the engine improved enormously. The pendulum piston 7 controls the flushing and outlet slots 23, 24 on both sides in a perfect manner asymmetrical to the piston dead centers, which results in favorable consumption values. The rinsing takes place at around the piston skirt 8, which requires rounded corners 25. This can also be done through the piston skirt with windows, as already described in the publication WO 88/06675 mentioned at the outset, as a result of which the piston crown is cooled from below. 4 and 5 is designed in a conventional manner with a one-piece cast iron block 30 and flanged-on cylinder head 31 and crankcase lower part 32, but the cylinders have a rectangular cross section. Their pre-cast, internally curved walls 34 and flat walls 35 can be processed, for example, by special broaching tools, which suggests an approximation of the mathematically precise curve shape by means of an arc 34 with a constant radius and is possible because of the relatively soft, elastic piston guidance.

According to FIG. 6, this is done analogously to FIG. 2a by coil springs 15, which, however, are not stored in bores, but in milled grooves 36 of the pendulum piston 37. This requires a removable piston head 38, which allows simple replacement of the piston guide and sealing elements from above. In this case, the central screw 39 serves as a center stop which is provided with a gap 40. wound piston guide spring 41. By comb-like formation of the inside of the sealing strips 42, their guidance is improved, the teeth 43 having a square cross section fitting exactly into the grooves 36 and protecting the springs 15 and 41 from hot fuel gases.

As an alternative, FIG. 7 shows a very simple, elastic piston guide by means of gas-filled spring elements 50 arranged on the end face made of highly heat-resistant, flexible material, for example PTFE. These cushion-like spring elements 50 guide the piston diametrically via end strips 51 and set the closed ends of the side sealing strips 52, at the same time sealing the overlapping joints of the sealing strips 51 and 52. These gas-filled spring elements thus replace the otherwise usual wave springs. A removable piston head 38 is unnecessary for assembly reasons and also because this progressive and silent air suspension means that a long service life can be expected. For this purpose, the inner flanks 53 of the end strips 51 and the base 54 of their guide grooves 55 must have a claw-shaped profile, according to FIGS. 8A and 8B, to which the cushion 50 clings wrinkle-free when pressed (FIG. 8B), and the Schl also shaped cover of the cushion 50 must be wrapped with stretchable fabric, for example made of carbon or Kevlar fibers.

The connecting rod shaft 60, with support and cooling ribs 61, is hollow cast, the core is supported by the opening 62, which is turned off by the semicircular gas slide 63.

These slides have edges 64 and 65 lying above and below on concentric circles around the center of the piston 1 and are loosely pivoted into corresponding clamps on the flat side walls. As a result, they do not participate in the pendulum movement of the connecting rod shaft 60 and thus cover the flushing and outlet slots 23 and 24 in FIG. 2, up to the curved cylinder walls 4. These slots can thus be made wider, which improves the gas exchange.

The connecting rod shaft 60 ends in the upper half 66 of the connecting rod eye, the large diameter of which is hindered by dynamic demands, as explained under FIGS. 2 and 3. The connecting rod cover 67 with balancing holes 67 ' is fastened by screws 68, the countersinks 69 of which are rendered harmless by a cover tape 70 with a tensioning screw 71. To further improve the sealing of the connecting rod loader 60, 66, 67, 70, the cover band 70 can have fine transverse grooves 72 with a labyrinth effect on the outside, especially if it consists of plastic instead of steel. The large diameter of the connecting rod eye 66, 68 results in a large inner diameter of the crankcase, which is closed by the cover 32.

This leads to the desired high degree of loading of the connecting rod supercharger and thus to the extreme power density of the engine (calculated average pressures up to 18 bar).

The pumping work is partially recovered from "top" dead center (FIG. 4) to point 73. If necessary, the throttle valve is not in the intake manifold 74, but in the form of two Um connected by a long hub! uf.tkl appen 75 directly behind the side flushing channels 78. When the cylinder is switched off or the engine is idling 75 ', almost the full amount of charge air is returned to intake 79 and recirculated with little loss. Channels 80 lead from the flushing channels 78 to the Low pressure injector 81 (air wrap of the jet).

Using the underpressure of the connecting rod supercharger, grooves 82 of the connecting rod eye and bores 83 and 84, which are arranged at a suitable location, can be used to meter the lubricating oil as required (recirculation flaps 75) and to be sucked in without a pump. Minimum oil consumption (the aim is to achieve a per mille) is the top priority for two-stroke engines today, which is probably only possible with low-friction floating pistons (the sealing strips of which may even have rotating ceramic needles). The position of the engine in the room is also decisive for lubrication and piston travel, preferably inclined to the left in FIGS. 4 and 2 (by approximately 15 ° to 150 °). The elastic motor fastening can take place on threaded eyes 82 of the lower part 32.

While the engine block of FIGS. 4 and 5 has large coolant spaces 83 for water or oil so that the moving parts run optimally, the cylinder head 31 is made, for example, of cast iron or ceramic, cermet without liquid cooling, and is therefore very easy to disassemble . Inspired by the work of Dr. Merritt from Coventry Polytechnic, it contains a combustion chamber formed by the trough 83 and the plate 84, which is at least partially filled, for example, with heat-resistant steel wool 85, some of which or completely coated with precious metal. By the piston movement of the piston in the area of top dead center 2, this combustion chamber is ideally flowed through in direct current by the charge, which ignites at start and low load on the spark plug 86, but otherwise on the steel wool 85 (secondary ignition with catalytic Combustion). This should result in the lowest fuel consumption and save an external catalytic converter. The elongated, cylindrical combustion chamber of FIGS. 11 and 12 of WO 88/06675 is also of interest, in particular in connection with direct injection (diesel, gasoline, gas or multi-substance). In the meantime, a conventional, hemispherical and / or semi-cylindrical combustion chamber according to FIG. 3 is also possible.

The round pendulum piston 88 with a connecting rod 89 and counterweight 90 is suitable for four-stroke engines of all kinds. According to FIG. 9A, a tried and tested seal consists of the guide ring 90 with an overlapped joint 91 in the transverse plane 92 and a radially freely movable one above it Feuerring 93 and an oil ring 94. The elastic Kol benführung takes place through two semi-circular, gas-filled pressure hoses 95, which are surrounded by a flexible band 96, for example made of PTFE. A corrugated profile of the inside of the band and the bottom of the groove, analogous to FIG. 8, is advantageous. arrested. The pendulum piston 88 can also have, for example, a square layout (suitable for four valves). Figures 9 and 10 also stand for, but only single-stage and therefore voluminous compressors.

A two-stage high-performance compressor can be derived from the internal combustion engine according to FIGS. 3 and 4. A wider, preferably quadratic pendulum piston and a much larger overflow slot 97 serve for this purpose, and if necessary an end channel 98.

Claims

P. ATENT REQUIREMENTS

1. Pendulum piston machine, with a cylinder crankcase with curved cylinder walls that adjoin an inner circular crankcase, where a pendulum piston with an integrated connecting rod shaft with a connecting rod eye is leaned against a crank pin, characterized in that the connecting rod eye is circular is designed as a counterweight, the design of the counterweight being used to generate a definable curve shape which is described by the piston center and that the pendulum piston is provided with sealing strips which have at least one shift in the region of the lateral amplitude of the piston allow generated curve shape.

2. Pendulum kol benmaschi ne according to claim 1, characterized gekenn¬ characterized in that the pendulum piston, connecting rod and counterweight form a unit, which are made of two interconnected half parts.

3. Pendulum piston machine according to claim 2, characterized gekenn¬ characterized in that the half parts abut each other in the pendulum plane.

4. Pendulum ol benmaschi ne according to claim 2, characterized gekenn¬ characterized in that the half parts abut each other in a normal plane to the pendulum plane.

5. Pendulum piston machine according to claim 2, characterized in that at least the connecting rod shaft is hollow.

6. pendulum piston machine ne according to claim 1, characterized gekenn¬ characterized in that the sealing strips are slidably mounted in end grooves and connected to each other via first pressure elements, which ensure a parallel displacement of the sealing strips with constant contact with the cylinder walls and second Druckele¬ elements , which cause a lateral centering of the pendulum piston.

7. Pendulum piston machine ne according to claim 6, characterized gekenn¬ characterized in that the first pressure elements are compression springs that are axially displaceable in through longitudinal bores, and the second pressure elements compression springs that are accommodated in parallel to the through holes in blind holes.

8. Pendulum piston machine ne according to claim 6, characterized gekenn¬ characterized in that the pendulum piston has a removable piston head, under which several parallel grooves are arranged in the pendulum piston, in which the pressure elements are attached.

9. Pendulum piston machine according to claim 8, characterized gekenn¬ characterized in that the piston crown with a central screw on the pendulum piston. is mounted, which also serves as a stop for the second pressure elements.

10. Pendulum kol benmaschi ne according to claim 6, characterized gekenn¬ characterized in that the end strips are slidably mounted in the front grooves, obei these are printed by closed, gas-filled, hose-like spring elements made of highly heat-resistant, flexible material with pressure on the cylinder walls , and that the spring elements are of the same length as the end strips and thus, with their closed ends, also exert pressure on the lateral strips.

11. Pendulum piston machine according to claim 10, characterized in that the inner flanks of the end strips and the base of their guide grooves have a wavy profile.

12. Pendulum piston machine according to claim 10, characterized gekenn¬ characterized in that the hose-like spring elements are wrapped with stretchable fabric.

13. Pendulum kol enmaschi ne according to claim 1, characterized gekenn¬ characterized in that the Penel kol benmaschi ne is a motor which is mounted with a position deviating from the vertical by 15 ° to 150 °.

14. Pendulum piston machine according to claim 1, characterized gekenn¬ characterized in that the combustion chamber is partially filled with a heat-resistant, at least partially coated with precious metal steel wool.

15. Pendulum piston machine according to claim 1, characterized in that the pendulum piston has a round cross-sectional shape and is provided with a round guide and sealing element.

16. Pendulum piston machine according to claim 15, characterized in that the guiding and sealing element is a ring which is guided in a radially displaceable manner by means of two semicircular, gas-filled pressure hoses.

17. Pendulum piston machine according to claim 1, characterized gekenn¬ characterized in that it is designed as a compressor.