DE1252965B - Direct current two-stroke internal combustion engine with an auxiliary piston to change the compression ratio - Google Patents

Description

Direct current two-stroke internal combustion engine with an auxiliary piston for changing of compression ratio The present invention relates to a direct current two-stroke internal combustion engine with an auxiliary piston, which is coaxially opposite the working piston, to the arbitrary Change of the compression ratio in the combustion chamber of the machine can be shifted and is used to control cylinder exhaust ports.

In two-stroke internal combustion engines, the principle of direct current purging can be used achieved the best results in terms of displacement and fuel consumption will. In addition, the asymmetrical control diagram gives the possibility of cylinder charging. The best-known internal combustion engines with direct current purging are the opposed piston engines and the internal combustion engines, in which the exhaust is through valves in the cylinder cover or by an auxiliary piston in the cylinder cover.

The use of high and low pressure pumps is common to most today Two-stroke machines have become indispensable. The diesel two-stroke engine requires z. B. a low-pressure pump as a lubricating oil pump and a high-pressure pump per cylinder as an injection pump, which as a cam pump or as driven by the compression pressure Pump can be executed. In the case of large diesel engines (ship engines) often because of various advantages, the pressure-dependent compression pump after preferred to the Archaouloff system of the path-dependent cam pump.

In internal combustion engines, especially in vehicle engines, is a quick change in the compression ratio to be made during operation he wishes. On the one hand, this enables the engine to run on different fuels to operate (multi-fuel engine), on the other hand, this can result in a sudden increase in load a knocking engine gear with its extremely unpleasant consequences can be avoided. There are a number of devices for changing the compression ratio known, which primarily have an auxiliary piston arranged on the working piston and its distance to the working piston by mechanical systems or pressurized oil systems is regulated. However, such devices require a considerable effort and therefore have in the event that they only have the function of changing compression can hardly be used. In addition to these devices with one on the working piston arranged auxiliary pistons are also devices for influencing the compression known to arrange an auxiliary piston opposite the working piston and its position change in the cylinder by mechanical, pneumatic and / or hydraulic systems.

Avoiding the maximum pressure peaks with knocking combustion can also take place by resilient elements, which partially store the pressure peaks and return when the cylinder pressure has dropped. Also here are mechanical, pneumatic and hydraulic arrangements with auxiliary pistons on or opposite the Working piston known, but which are also so expensive that in the utility engine it is waived.

The internal combustion engines with freely movable auxiliary pistons through which the compression adjustment or the storage of the maximum pressure peak. zen or the direct current flushing is effected in the two-stroke engine are in manifold Executions known. In some versions, the auxiliary piston is via a Piston rod connected to a piston with a smaller diameter, which in a hydraulic or pneumatically actuated cylinder works. In other known systems the auxiliary piston is freely floating in the working cylinder and is also through pneumatic or hydraulic means held in such a position that, for example the size of the compression space between the auxiliary piston and the engine working piston can be influenced.

The systems mentioned work either pneumatically, with the auxiliary piston directly or via the smaller piston connected to it against the pneumatic one Work equipment is supported, or they work hydraulically, likewise the entire side of the auxiliary piston facing away from the compression chamber or that with the Auxiliary piston connected smaller piston a boundary wall of a liquid space form, which is opened and closed in time with the machine so that the auxiliary piston in the combustion phase is hydraulically blocked.

The majority of these systems only aim to maintain a constant Compression end pressure and in some cases the accumulation of the maximum pressure peaks with knocking combustion. As a result, the auxiliary piston does not perform any major stroke movements at each work cycle and can therefore use the exhaust system of the machine for the purpose do not control the DC purging.

In addition to these systems, auxiliary piston arrangements are of course known, in which the auxiliary piston controls the outlet slots. With these the auxiliary piston either mechanically operated, so that the machine is basically like an opposed piston machine works with two working pistons in one cylinder, or the auxiliary piston movement takes place pneumatically with specially supplied compressed air. These systems are then either almost as expensive as the opposed piston machine or can be realized they do not have any other than the direct current flushing and the change in compression other functions.

From the above it can be seen that for the various Facilities and improvements of a powerful and against improper overuse protected motor just as many different building elements are necessary. These building bodies, such as B. the mechanically or pneumatically operated auxiliary piston for direct current flushing, the devices for changing the compression and for storing the maximum pressure peaks make the engine more expensive and in many cases force despite the considerable advantages on their waiver.

The invention is based on the functions of these various Execute facilities with an appropriately designed component and thus the engine is not more complex, but with the advantages and improvements mentioned to manufacture. It is also an object of the invention that this component also as Low pressure pump for engine lubrication and as a pressure generator for auxiliary drives and also acts as a high pressure pump for fuel injection.

In order to achieve this object, according to the invention, is known per se Way the auxiliary piston, under the force of cylinder pressure and elastic means upright, free-floating and with a piston of smaller diameter above connected to a piston rod, the piston being controlled by a periodic control subjected hydraulic medium is acted upon, and it also forms the piston with a smaller diameter one acting in both directions, through the control hydraulic stop releasable in one direction and forces it through its upward movement the hydraulic medium to a circuit through aggregates, such as lubricating and work-performing Auxiliary equipment of the machine.

According to a further embodiment of the invention is the hydraulic Stop forming hydraulic space via a line into which a periodically controlled Gate valve and a distributor tap is switched on, connected to a container. Check valves arranged directly on the hydraulic cylinder prevent this a backflow from the intended flow direction. The gate valve will driven at crankshaft speed. Through the one behind the gate valve The distributor tap located can allow the hydraulic fluid to flow freely to the container throttled and wholly or partially directed into a parallel junction will. This junction consists of bearings on the engine to be lubricated and other engine parts and pressure medium consumers. This makes the function of a Low pressure pump fulfilled. In a lower one, from the piston rod between the auxiliary piston and piston of smaller diameter penetrated working space of the hydraulic cylinder open several holes, which seen in the longitudinal direction at different heights and are connected to a piston valve via channels or lines. Behind This piston valve unite these lines and lead together to the Container. Auxiliary pistons and pistons with a smaller diameter have their lower ones Stop at the respective hole which is connected to the container via the piston valve connected is. With this hydraulically adjustable lower stop, the auxiliary piston Hydraulically blocked in the working cylinder at an adjustable height before the combustion phase and thus the compression ratio can be adjusted. The function of a storage the maximum pressure peaks with knocking combustion, as far as this is the result of the adjustable compression ratio still occur at all, the piston in Hydraulic cylinder likewise, in that the liquid in the upper working space along with it the liquid column in the line up to the gate valve as a liquid spring works. The spring effect can be determined by the area ratio of the auxiliary piston and piston can be influenced with a smaller diameter. So far, the training according to the invention of the control piston and hydraulic system in its functions as a control organ of the Outlet slots of a direct current machine, device for adjusting the compression ratio, Device for the elastic absorption of harmful maximum pressure peaks and as a low pressure lubrication pump has been described. The function as a low-pressure lubrication pump requires that the working medium has adequate lubricating properties. Should the described In addition to the functions mentioned, the system also functions as a high-pressure injection pump meet, the working medium must be fuel oil and also have sufficient lubricating properties to have. Only if this requirement is met, the subject of the invention can except the other functions of the low-pressure lubrication pump and high-pressure injection pump at the same time be. If the working medium is only lubricating oil, the the high pressure injection pump cannot be met. Is the working medium against it? only fuel oil, the function of the low-pressure lubrication pump must be omitted.

According to the invention, the additional function of a high-pressure injection pump is required only changes to the gate valve. The gate valve blocks the upper working area of the hydraulic cylinder including the line up to the gate valve from the beginning of the compression stroke until the end of the work cycle, and then the slight excess gas pressure in the work cylinder to be used for the low-pressure lubrication pump. At the end of the compression stroke it says but the upper working space under high pressure according to the compression end pressure and the gear ratio from auxiliary piston to piston with a smaller one Diameter. It is therefore sufficient to briefly activate the gate valve at this point in time to induce an additional lifting or rotary movement in order to avoid that of the upper working area opening line partially and for the duration of the injection time with a to Connect injector leading line. Injection according to quantity and duration can thus be determined by the size and the time of an additional movement of the gate valve be regulated in the blocked state (end of the compression cycle).

An exemplary embodiment of the invention is shown in the drawing. It shows fig. 1 shows a cross section through the machine with the lowest position of the auxiliary piston and piston with a smaller diameter (start of work), FIG. 2 shows a cross section through the machine with the uppermost position of the auxiliary piston and piston with a smaller diameter (exhausting and flushing), FIG. 3 shows a longitudinal section through the piston valve for adjusting the compression ratio, FIG. 4 shows a longitudinal section through the gate valve, FIG. 5 shows section A-B according to FIG. 4, when the gate valve cannot effect the high-pressure injection, FIG. 6 shows the section A -B according to FIG. 4, if the gate valve is modified so that it can additionally effect the high-pressure injection, in the non-injecting position, FIG. 7 the section AB according to Fi g. 4 according to FIG. 6, but in the injecting position, FIG. 8 is a circuit diagram of the entire hydraulic system.

In Fig. 1 shows the starting work cycle. An auxiliary piston 1 is firmly connected to a piston 2 with a smaller diameter, and a hydraulic cylinder 3 is attached to the working cylinder 5 via a bell-shaped hood 4. The auxiliary piston 1 and the piston 2 with a smaller diameter are pressed into their lowest position by a compression spring 6 when the working space is depressurized. Instead of the compression spring 6, the space 7 located above the auxiliary piston 1 can also be designed as an air spring, in that compressed air of a few atmospheres overpressure is fed to it via a connection 8. The compressed air can be regulated as a function of the engine speed in such a way that the pressure is increased as the engine speed increases, and vice versa. Lines 10 a, 10 b , 10 c extend from a lower space 9 of the hydraulic cylinder 3 and open into space 9 at different heights. These lines 10 a, 10 b , 10 c lead to a piston valve 11, which is shown in FIG. 3 is shown. The piston 12, which is movable in this piston valve 11, blocks the opening lines 10 a, 10 b, 10 c depending on the setting, whereby the space 9 either over all lines 10 a, 10 b, 10 c or only over the two upper lines 10 a, 10 b or only via the upper line 10 a with a container 29 (Fig. 8). This allows the lower stop position of auxiliary piston 1 and piston 2 with a smaller diameter to be regulated. In Fig. 1, the piston 2 with a smaller diameter and the auxiliary piston 1 find their stop at the confluent line 10 a, because in FIG. 3, only this line is connected to the container 29 due to the position of the piston 12. The lowest compression ratio is thus set. If, on the other hand, the piston 12 (FIG. 3) is pulled out so far that the lines 10b, 10c are also exposed, the piston 2 and the auxiliary piston 1 only find their stop at the confluent line 10c (FIG. 1 ). The highest compression ratio is then set.

When the engine is working, there is a constant back and forth movement of working fluid between the space 9 (FIG. 1), the piston valve 11 (FIG. 3) and the container 29. This is in FIG. 8 represented by double arrows. The space 9 is sealed against the piston rod of the piston 2 by a conventional sealing element 13. In the starting work cycle according to FIG. 1, the upper hydraulic chamber 14 is completely filled with working medium and is under still increasing high pressure. The only inlet check valve 15 is closed. The working medium in the check valve 16, which is only discharging, and in the adjoining line 17 up to the gate valve 18 (FIG. 4) is under the same high pressure. The gate valve 18 shown in Figure 4 is a pressure-relieving piston valve of conventional design; through it, the line leading to a distributor tap 21 or container 29 (FIG. 8) can be shut off. For this purpose, the piston 19 is pushed in against the action of the spring 20, advantageously by means of a device shown in FIG. 4 cam, not shown, which can be arranged on the engine crankshaft, but also on the cylinder head and is driven at the crankshaft speed. Towards the end of the work cycle, the cam releases the piston 19, whereupon the spring 20 pulls the piston 19 back and opens the gate valve 18. The combustion gases, which are still under overpressure, can thus move the auxiliary piston 1 together with the piston 2 with a smaller diameter upwards, displace the working medium from the hydraulic chamber 14 and transfer it via the line 17 and the open gate valve 18 to the distributor valve 21, ie partly to the container 29 and partly Press to the lubrication points and pressure medium consumers 30, 31, 32. This upward stroke of the auxiliary piston 1 and piston 2 goes so far until the piston 2 closes the bore of the discharging check valve 16 and thus strikes hydraulically. This position is shown in FIG. 2 (exhausting and flushing). The auxiliary piston 1 opens the exhaust ports, and shortly afterwards the working piston opens the scavenging ports. After the combustion chamber pressure has dropped and the purging is complete, the compression spring 6 or the air spring in chamber 7 begins to push the auxiliary piston 1 with the piston 2 with a smaller diameter back down until the lower hydraulic stop is reached according to the adjustment device already described. The piston 2 with a smaller diameter sucks working medium into the hydraulic chamber 14 via the inlet check valve 15. In the lowermost position of the auxiliary piston 1 and the piston 2, the cam closes the gate valve 18, the compression stroke begins, and the work cycle is repeated in the manner described.

If, due to special circumstances (early ignition, rapid increase in load, inferior fuels), high combustion pressure peaks and thus knocking occur during the onset of combustion, the pressure fluid in the hydraulic cylinder 3 and in the line 17 to the gate valve 18 acts as a compressible column of fluid and thus avoids the extremely harmful knocking phenomena . For such an elastic effect, the brief high combustion pressure peaks only need to induce a sufficiently high pressure in the hydraulic cylinder 3 in order to compress the liquid to a small extent. The elastic effect can be influenced by the appropriate choice of the area ratio between the auxiliary piston 1 and the piston 2 with a smaller diameter.

To protect the compression spring 6 from excessive heating, is a consisting of heat insulating material washer 22 between the compression spring 6 and the auxiliary piston 1 arranged.

The gate valve 18 according to FIG. 4 is currently only in its function has been described as a shut-off component. This corresponds to training without High pressure injection. In this case, the cross-section of the gate valve has 18 the in F i g. 5 shape shown, which is the shape of a known, pressure-relieving Piston valve corresponds. The gate valve 18 is shown in FIGS. 6 and 7 on the Modified requirements of the additional high pressure injection according to the invention.

In Fig. 6, the previously free annular space is divided into two spaces 23, 24, which are connected to one another via the transverse bore 25 located in the piston 19. A pressure equalization is thus established for the piston 19 again. The transverse bore 25 is also connected to a further transverse bore 26 which forms an acute angle with the bore 25. This transverse bore 26 can pierce the piston 19 completely and thus result in two openings branching off from the bore 25, as shown in FIG. 6 and 7 is shown. However, it can also only penetrate as far as the center of the piston 19 and thus only form an opening branching off from the bore 25. Accordingly, two bores 27, 28 or only one bore can open into the gate valve housing. High-pressure lines lead from these bores 27, 28 to the injection nozzles. If, at the injection point at the end of the compression stroke, the piston 19 is rotated for the duration of the injection time in such a way that the transverse bore 26 is congruent with the bores 27, 28 (FIG. 7), the final compression pressure on the auxiliary piston 1 causes over the piston 2, the line 17, the just named bores 25, 26, 27, 28 of the gate valve 18 and the injection nozzles the fuel injection into the working cylinder.

Simultaneous high-pressure injection into several cylinders in the same working phase can be carried out from a gate valve, as is the case for all cylinders in a working phase, e.g. B. a multi-cylinder marine engine, only one gate valve is required. Are z. B. with an h-cylinder machine always two cylinders in one work phase, then h / 2 gate valves are sufficient, which are actuated by a correspondingly designed cam disk. The gate valve 18 can only take over the functions of the low-pressure lubrication pump and the high-pressure injection pump at the same time if the working medium used is fuel oil that also has adequate lubricating properties. In Fig. 8 shows the circuit diagram of the entire hydraulic system for a single-cylinder machine. The individual units are symbolically drawn. The main circuit runs from the container 29 via the hydraulic cylinder 3 (hydraulic chamber 14), the gate valve 18 and the distributor valve 21 back to the container 29. A pressure medium consumer group branches off from this main working group; it leads from the distributor valve 21 to the z. B. three specified pressure medium consumers 30, 31, 32 and from here back to the main working group. Another separate working group is the working fluid that is moved to and fro between the hydraulic cylinder 3 (space 9), the piston valve 11 and the container 29.

In Fig. 8 is also that of the gate valve 18 to the working cylinder leading high pressure injection line indicated by dashed lines.

Claims (7)

Patent claims: 1. Direct current two-stroke internal combustion engine with a Auxiliary piston, which is coaxially opposite to the working piston, to the arbitrary Change of the compression ratio in the combustion chamber of the machine can be shifted and is used to control cylinder exhaust ports, characterized in that that in a known manner the auxiliary piston (1), under the force of the cylinder pressure and elastic means standing, freely arranged and with a piston (2) smaller diameter is connected via a piston rod, whereby the piston (2) acted upon by a hydraulic medium subject to periodic control is, and that the piston (2) one acting in both directions, by the control forms releasable hydraulic stop in one direction and by its outward movement the hydraulic medium to a circuit through aggregates such as lubricating and work-performing Forces auxiliary equipment of the machine. 2. Direct current two-stroke internal combustion engine according to claim 1, characterized in that the hydraulic space (14) forming the hydraulic stop is switched on via a line into which a periodically controlled gate valve (18) and a distributor valve (21) are connected, with a container (29) connected is. 3. Direct current two-stroke internal combustion engine according to claim 1 and 2, characterized in that pressure fluid for the engine lubrication, the lubrication of other units and for work-performing systems is branched off from the distributor tap (21). 4. Direct current two-stroke internal combustion engine according to claim 1 to 3, characterized in that the inner hydraulic chamber (9) penetrated by the piston rod of the auxiliary piston (1) and the piston (2) has a plurality of longitudinally staggered lines (10 a , 10 b, 10 c) go out, which are connected to a piston valve (11) and the container (29) in such a way that the stepped lines (10 a, 10 b, 10 c) are sequentially blocked by the piston valve (11) and thus the inner The stop position of the auxiliary piston (1) and the piston (2) is variable. 5. direct current two-stroke internal combustion engine according to claim 1 to 4, characterized in that for the reduction of very high combustion pressure peaks in the outer hydraulic chamber (14) and in the line (17) to the gate valve (18) located liquid column by a correspondingly large area gradation between the Auxiliary piston (1) and the piston (2) can be compressed. 6. Direct current two-stroke internal combustion engine according to claim 1 to 5, characterized in that the gate valve (18) located in the blocking position is subjected to an additional movement at the end of the compression stroke, which via transverse bores (25, 26) the outer hydraulic chamber (14 ) connects to the injection nozzle for the duration of the injection time and thus the injection into the combustion chamber is effected by the compression end pressure, which is increased by the transmission ratio of the auxiliary piston (1) and piston (2). 7. DC two-stroke internal combustion engine according to claim 1 to 6, characterized characterized in that, in the case of multi-cylinder machines, all are in the same working phase Working cylinder of a gate valve (18) for the purpose of blocking and the High pressure injection are actuated. Publications considered: German U.S. Patent No. 290,786; Swiss patent specification No. 236 284.