DE1093690B - Recoil motor for watercraft - Google Patents

Description

Recoil motor for watercraft The invention relates to boat propulsion with the help of a recoil motor, in which sucked into a combustion chamber Fills of a mixture of air and an easily and quickly explosive fuel ignited in successive explosions and the combustion gases through a unidirectional non-return valve can be inserted into a thrust tube, which a water inlet port monitored by a check valve and a discharge port possesses, and in which the combustion gases the water column located in the thrust tube eject like a piston.

Reach the previously known recoil motors of this type only poor performance, as the compression achieved is insufficient and the letting in as well as expelling the water from the thrust tube loaded with excessive resistance is. In a known recoil engine of this type, the combustion chamber extends from the ignition point directly to the one monitored by a non-return valve It flows into the thrust tube, and this is at its front end with a non-return valve acting flap unit, which gives the thrust tube an extraordinary high front resistance. Because Idas aggregate consists of numerous long lamellas, which have a considerable frictional resistance along the entire flow length offer and, due to their design, also not that for the flawless work of a such a pulsating drive required rapid closing and reopening guarantee.

Other known recoil motors for watercraft require to their Operation of a compressor, for this reason alone, are easy to use without moving driven parts working independent device not suitable. Neither the requirement of handiness and economy is met by recoil motors, which work according to the Venturi principle in the outflow space and on the inlet side of the Thrust tube have no valve at all. Because the recoil motors of this kind which also require an external drive to start, only work with poor efficiency. The same applies due to the practical lack of any compression in the combustion chamber also for another known recoil drive for watercraft, in which a tubular working space in its upper part forms a combustion chamber while the lower pipe part directly adjoining the combustion chamber Has water inlet opening monitored by a flap valve and at the rear to the discharge the water is open. Even this type of water inlet allows at best a very slow explosion and has therefore not proven itself. Something like that Finally, it also applies to a pump that works according to the recoil principle can also be used as a ship propulsion system. With this device the only ends with a baffle plate that covers part of the cross-section of the chamber and is equipped with a combustion chamber without the interposition of a non-return valve directly in a thrust tube the front end of which is a flap valve monitoring the water inlet and at its rear end is also attached a valve, which the discharge tube against the other way around, is supposed to shut off the inflowing liquid, which, however, almost all of the energy was destroyed. Also the efficiency of this pump, at least as far as it is for the boat drive was to be used, as a result, was poor.

The invention eliminates these shortcomings of the previously known, based on the recoil principle boat drives in that in a motor of According to the invention, the combustion chamber in at least one of the generic types described at the outset two chambers separated from each other by non-return valves is divided and with the last chamber opens into an extension of the thrust tube, which, in the direction of travel seen, behind a venturi-like constriction of the thrust tube, and that the valve that opens and closes the water inlet opening of the thrust tube, designed as a low-inertia, fast-responding check valve with butterfly valves is, as blades pivoted about radial axes from a through the Water-driven, freely rotating hub in the manner of a turbine wheel are worn. A recoil motor equipped in this way achieves good performance even without using a special compressor. To the The engine can be powered by liquid and gaseous fuels, with air Form highly effective explosive mixtures. By the described subdivision of the combustion chamber is an additional gas dynamic compression and thus greater performance achieved through better combustion. One such improvement the explosion pressure by dividing the combustion chamber into several Constrictions or poppet valves are separate departments in and of themselves known. So one has z. B. in pumps for heating gas delivery by a so formed Chain of chambers achieves a pressure increase even with such explosive mixtures, which were not pre-compressed in the first chamber. On recoil motors for boat propulsion, where a pre-compression is essential to achieve good efficiency is required, this principle has not yet been applied. His However, advantages for the special area of boat recoil motors can also only be exploited if one takes care that the pre-compression achieved does not become: in the occurrence strong blows and vibrations exhausted, as is the case with the one to be set in motion Recoil medium, the water, would otherwise easily happen; rather, it must also by using a low-inertia check valve on the flow side of the Thrust tube can be achieved that the opening and closing of the water inlet port in the rhythm of the explosions takes place so quickly and completely that in the open state the water flows largely smoothly into the thrust tube, so that there is a possible continuous movement is assured. This is achieved through the described, Particularly low-inertia and fast-responding turbine-wheel-like check valve according to the invention with its shut-off blades rotatable about radial axes. A Such a valve is indigkeit Verstellgeschw indigkeit, closure capacity and eddy-free Passage of the lamellar valves used in recoil motors of the type mentioned at the beginning with their long, resilient lamellae, which cause strong flow losses and vortex formations make inevitable, far superior.

For the operation of the recoil motor according to the invention is finally also important at which point of the with the mentioned novel water inlet valve equipped push tube the introduction of the combustion gases into the push tube takes place.

The thrust tube has behind the one arranged in its front part circumferential check valve on a venturi-like constriction, which then an extension follows. The combustion chamber flows into this extension, whereby a quick and perfect formation of the for sucking in the new fuel mixture filling Serving vacuum is guaranteed with each explosion cycle.

The mentioned extension into which the explosion chamber, through the Non-return valve closed, opens, then closes to the rear Part of the thrust tube, in which the water gets its acceleration and piston-like is ejected backwards. The rear ejection part of the The extension tube is equipped with an extension that acts as an expansion buffer. These Extension serves to dampen shocks. It is followed by a pressure-increasing one Trumpet tube, which forms the end of the thrust tube. The water column and that they driving combustion gas are emitted in such a way that the water like a piston acts. For this purpose, the discharge tube is provided with a smooth inner wall.

The check valve attached to the water inlet end of the push tube in the described embodiment in the manner of a freely rotating turbine wheel pivotable blades or vanes that form the butterfly valves, represents a new type of valve, which is not only suitable for recoil motors of the type described .is, but also with advantage as a non-return valve in lines and pumps of all Can be used where liquids, vapors and gases are conveyed by a conveying type The aggregate is to be moved in one direction. Such a valve can in principle can be used wherever recoil is to be feared and where it occurs quickly a flow opposite to the normal flow direction can be prevented must, e.g. B. Also with ventilation impellers and the like. Such a check valve low resistance ensures a smooth, practical in one direction smooth flow of the medium through which its blades pivot will. Opposite to the direction of flow, on the other hand, such a freely running one offers Valve wheel with self-regulating paddle movement a closed, each backflow blocking disk. The valve's flap vanes that serve as vane surfaces are at the same time under the influence of the effect of centrifugal force, the so that it has a certain directional effect. The valve is in the closed position namely the center of gravity of each folding wing further from the axis of rotation (not from the folding axis) than in the open position. With rotation this Rotary valve, the mass of the folding wing is the influence of the outward Exposed to centrifugal force, which thus tries to move the center of gravity of the wings in the position furthest from the axis of rotation, d. H. in the closed position the wing to bring. Valve springs are not required.

This non-return valve, which responds quickly with almost no inertia, is united with a simple and space-saving design the advantage of a good closing effect in the countercurrent sense with the advantage of an almost resistance-free release of the flow in the direction of flow. The changeover from one to the other operating mode is quick and easy practically no power consumption.

In the application of the described recoil motor for boat drives such a revolving check valve still offers the possibility of the flap vanes to be sharpened at the leading edge in order to cut through water plants and the like to render harmless.

For ignition taking place in the usual way by means of a spark plug of the fuel mixture in the combustion chamber, it is advisable to use an ignition device use which is adjusted to the particular conditions under which Recoil motors of the type described have to work when propelling the boat. It acts On the one hand, there is a large degree of insensitivity to moisture on the spark plug and in the combustion chamber, as is unavoidable in boat operations. And continue to act it is about the adaptation of the firing rhythm to the special conditions in such pistonless pulsation motors. There are no rotating or and moving parts available that are used to control the firing order could be, and continue to be the spark plugs of such engines relatively wet when stopped, so that a particularly strong and reliable Ignition device must be provided. When the engine is started, the spark produced must be so strong that the moisture on the spark plug atomizes and the combustion mixture is ignited. When running the engine when water does not reach the spark plug to the same extent when it approaches as if it were at a standstill, the sparks can then be correspondingly weaker: on the other hand, they have to be faster, depending on the power required from the engine Sequence occur one after the other. The rhythm of work and the performance of such Engines is determined solely by the number of ignition devices initiated Controlled ignition processes. To meet these demands and thereby the Recoil motor a particularly high one: maintained under all working conditions To give a level of reliability, it is useful to have a device for the ignition already proposed type to use with idem in a known manner to the terminals a high voltage DC power source, one high voltage charge capacitor and two consecutive spark gaps are connected in parallel, one of which when reached the flashover voltage causes the capacitor to discharge and thus also causes the spark to pass through the other, namely the spark plug, and in the for the pistonless recoil pulsation motor for boat propulsion, however, it is now the ignition spark power (Current times voltage) at the spark plug and the inversely proportional: the Spark frequency that determines engine performance by adjusting the spark plug upstream auxiliary spark gap is regulated.

When starting the engine when the spark plug is still wet, the sparkover voltage effective at the spark plug can be adjusted by setting a large Distance at the auxiliary spark gap must be dimensioned very high. At a high voltage the charging of the ignition capacitor before the sparkover is particularly high, and in this way a spark is generated, the moisture that may be present atomized and guaranteed reliable ignition.

After starting, if the conditions in the explosion room are suitable for the Ignition have become cheaper, the energy of the ignition spark can be smaller. The distance at the auxiliary spark gap is thus reduced and the flashover takes place at a lower voltage. This also increases the charging time of the ignition capacitor and the number of ignitions in the unit of time is increased, .d. that is, the engine runs faster and its power output increases themselves. Because the energy of the ignition spark is adapted to the respective conditions and can therefore be reduced accordingly under favorable conditions, the Consumption of the power supplying batteries can be kept extremely economical.

The described boat engine, which works according to the recoil principle, has compared to the usual piston engines those advantages, including the recoil engines make use of aircraft, namely light weight, simple construction and ease of use, so that the motor can be used as an easily transportable device easy to install on all boats, especially as an outboard motor.

Further details and features of the invention emerge from the following Description of an embodiment shown schematically in the drawing is. Fig. 1 shows a sectional view through a recoil boat engine according to the Invention in longitudinal section, Fig. 2 a partial section i on a larger scale through that Part of the thrust tube in which the free rotating check valve with its pivotable blades is mounted, Fig. 3, the view of one of these blades of the Valve with sharpened cutting edge, seen in the direction of the folding axis, and Fig. 4 is a schematic representation of a for the recoil boat engine according to the Invention particularly suitable ignition device.

The engine consists primarily of a combustion chamber 1 and from a thrust tube lying in its entire extent below the water level 2, 3. The opening 5 of the combustion chamber in the scraper tube is through a flap valve 6 covered. On the side of the combustion chamber opposite the thrust tube this is provided with a start-up pump 4. The combustion chamber is divided into several Divided chambers to achieve a pre-compression, through which a high degree of efficiency is guaranteed. In the exemplary embodiment shown, there are two chambers 7 and 8, which are connected to one another by a flutter valve 9, which .als Check valve in chamber 8 opens. The poppet valve is located in the chamber 7 10, through which the fuel mixture is sucked in. The flows to the carburetor 11 Combustion air through the openings 12 in the pump housing and through the stationary one Piston 13 of the hand air pump, so that the cylinder of this starting air hand pump at the same time is part of the inlet pipe for the combustion air. Behind the inlet valve 10 is the spark plug 14, which is controlled by the above-mentioned ignition device.

The ignition device shown schematically in Fig. 4 draws electricity a battery 34. This becomes an ignition transformer by a chopper 35 36 fed and transformed. A capacitor Co serves to dampen the primary circuit. Except for the secondary coil for .the high voltage of the ignition transformer 36 is on this another heating coil for a high-voltage rectifier tube connected. Of the Direct current rectified and chopped through tube 37 flows into the collecting capacitor Cl and is passed through a variable resistor R1 in the running capacitor C2 led. From the capacitor C2, the adjustable auxiliary spark gap 38 gets the desired tension. When the voltage of the capacitor C2 exceeds the withstand voltage the auxiliary spark gap has reached 38, the spark jumps at this and at the same time on the spark plug 14 over.

The spark plug 14. Is bridged by a stabilizing resistor R2, which causes the whole voltage difference of the capacitor before sparking C2 is effective at the auxiliary spark gap. One would be bridging the spark plug 14 through the resistor R2, .then the arcing would occur at the auxiliary spark gap 38 not only through the distance at the auxiliary spark gap, but also through influences the conditions at the spark plug (moisture, soot). The one with the spark plug electrodes Resistor R2 connected in parallel is dimensioned so large that when the Spark at the auxiliary spark gap, the amount of charge on capacitor C2 does not immediately can be discharged and the voltage of the condensate Bators C2 occurs on the spark plug electrodes, creating the powerful spark here. It is not important whether the spark plug gap is set correctly because even a spark plug electrode short-circuited by moisture is flawless works, eliminating the moisture.

The auxiliary spark gap 38 is designed as an adjustable rotary contact pair. As already stated above, by adjusting the distance between the contacts 38, but also by changing the resistance R1, the pulse frequency can be easily regulated will. When adjusting the contact distance on the auxiliary spark gap changes but also in the manner shown the power of the .überspringenden spark. If the contact distance is large, this is the flashover voltage and consequently also the charging voltage of the ignition capacitor C2 high, and this charges in a relatively long time on a high charge (capacity times voltage). So the spark just jumps relatively seldom, but then with high performance over. If the contact spacing is determined by the If the auxiliary spark gap is reduced, the flashover and charging voltage are lower, charging is faster and ignition is relatively quick often. It is therefore possible by adjusting the auxiliary spark gap 38, depending on the Operating mode of the engine a very intensive or a more frequently occurring, but to generate energy-saving sparks and so the power output of the motor alone to control from the ignition. When starting up after a standstill, one first selects a large distance to a more powerful ignition spark, the one in the explosion room Existing moisture is eliminated, and with continuous operation one becomes the contact distance decrease to shorten the firing sequence and the pulsation and power output of the engine. Since the spark time can be set very short, several hundred times shorter than with the known inductive methods, can also Motors with high pulsation numbers can be controlled properly and reliably.

Instead of the chopper 35 and the ignition transformer 36, the alternating high voltage also through the well-known electronic high-frequency oscillations by means of a tube or a power transistor, provided that this route is used in individual cases is economically viable.

In the context of this patent, the ignition device just described, but only its use in combination with the recoil motor described placed under protection. The ignition device mentioned ensures that the initial explosions are flawless, regardless of whether the underwater spark plug is wet or sooty. The power of the engine is determined by the driving speed with the increasing rhythm of the explosion controlled. The advantage is also that, as a result, explosive violent Ignition sparks a reliable ignition even with different fuel-air mixtures is guaranteed. So there is no fear that if the explosions occur in the chamber 7 initially begin under a slight overpressure, due to fluctuations in the Air-fuel mixture malfunctions can occur, as is the case with the classic Induction igniters the case. The generated by the said igniter a lot Rather, mixtures of different composition ratios also produce stronger ignition sparks certainly too strong explosion. The resulting pressure wave pushes that explosive gas mixture from the first chamber 7 through the flutter valve 9 faster into chamber 8 as the flame spreads. That is why it forms in the second chamber 8 already a pre-compressed fuel-air mixture state, which is important for the achievable performance. Combustion is sufficient a small amount of fuel to move the mixture from chamber 7 to chamber 8 to compress. Finally, the flame then strikes through the flutter valve 9 and also ignites the compressed mixture in the chamber 8, whereupon the expanding ones Combustion gases through the flap valve 6 with great violence on the Water act in the thrust tube 2 and express it out of its discharge part for 3 hours.

In order to increase the pre-compression effect described, the combustion chamber can also be further subdivided into three, four or more chambers, which are below are separated from one another by low-inertia valves of the tongue or flutter design. At the same time, these valves prevent backflow into the preceding chambers, in which there is already a lower pressure.

While the water is now due to the violent explosion in the combustion chamber ejected in the direction of arrow 15 to the rear and by the resulting reaction force the motor is driven forward in the direction of travel, prevents this in the front part the thrust tube attached check valve 16 that also water through the inlet opening 17 can flow out. The length of the discharge tube 3 is chosen so that the expanding gases the water only about up to the one shown in dash-dotted lines Line 18 a can slide. From this line on, the gases pull out again together. Through this contraction and through the inertia of the rapidly flowing out Water, there is a vacuum in the chambers 7 and 8 of the combustion chamber, and thereby is fresh fuel mixture through the poppet valve 10, the carburetor 11 and the Pump 4 sucked in. At the same time, the vacuum sucks through the revolving non-return valve Water through the front inlet port, and also with the help of the driving speed the resulting back pressure, the thrust tube 2, 3 is quickly filled with water again. 1 "Do - the described process is repeated with the next ignition in the combustion chamber.

The performance of the engine increases with the number of explosions per unit of time. The faster the explosions follow one another, the greater the thrust. Apart from that of the good efficiency is therefore a high number of explosions to achieve a good engine performance. important. But should an explosion take place while If there is still a vacuum in the thrust tube 2, 3, the explosion would become weaker. It is therefore important to end the suction period quickly and in the extended part 2 of the thrust tube (behind the housing of the check valve 16) and in the combustion chambers 7 and 8 to quickly generate a certain overpressure again. Serves this purpose the arrangement that the thrust tube where the combustion chamber opens at 5, has a larger cross-section than in its front part. The one behind the check valve 16 attached constriction 18 and the then following expansion of the thrust tube part 2 generate with the help of the driving speed according to Bernoulli law a strong overpressure. The suction time is reduced to a fraction of that Depressed time it would take for the vacuum to break if the water inlet port and the widened part 2 of the thrust tube at the point where the combustion chamber joins would have the same cross-section throughout. The flap valve 6 serves only to avoid unnecessary To switch off the formation of eddies, therefore, has for the thermal process and the pressure curve : the process described has no meaning in itself. It's not even supposed to be hermetic close because of the overpressure in the valve housing after the suction period 2 and should be balanced in the chamber section 8.

The water inlet valve 16 of the thrust tube acting as a check valve is designed in the manner of a freely rotating turbine wheel, the blades of which are around radial pivot axes are rotatable and on the one hand under the influence of the flowing through Water and on the other hand the centrifugal force. The one attached to this water inlet valve The demands made are that the valve should be as inertial as possible, quickly urid works reliably that it can withstand the high explosion pressure after which Explosion but immediately let in as much water as possible so that it gets you should have the lowest possible front resistance and flow resistance, and that it after all, not from the small and large impurities floating in the water blocked or impaired in its function. Developed for this purpose Check valve in the manner of a freely rotating turbine wheel fulfills these conditions in an excellent way and allows such a high number of explosions (about ten times as much explosions in the unit of time than with the valves previously used was possible) that the water flows almost continuously through the thrust tube. to For this purpose, a freely rotating hub 21 is built into the thrust tube, which about i the central axis 22 rotates like a small free-wheeling turbine when the water is through the front inflow opening 17 flows into the thrust tube 2. To make this twist blades 19 are attached to the hub and pivot about radial axes 20 as flaps are. By aerodynamically shaped guide bodies 23 and 24 in the interior of the thrust tube it is ensured that the water flows in with as little friction and turbulence as possible. With this inflow, if there is a lower pressure in the front part 2 of the thrust tube prevails than in the outside water, the blades 19 together with the hub form one Type of turbine wheel that rotates rapidly as the water flows in. The water flows to the thrust tube without twisting, but the hub rotates in that a laterally acting entry impact acts on each blade, because the inflowing water after each explosion only the closed shovels resp. Must open flaps. This creates a torque around the valve axis. In the An explosion, i.e. when there is overpressure inside the thrust tube, subside the blades 19 then immediately back on the concentric stop and support edges 25 and thereby form an annular disc, @ which every movement of water in the direction to the inlet opening 17 prevented. This conversion from freewheel turbine i to Non-return valve runs periodically with the number of explosions with constant circulation of the check valve. The edges 26 of the blades lying in the direction of rotation or valve flaps are sharp so that everyone gets between them Inflowing aquatic plants can be cut into small pieces without the risk of clogging can also exit again freely from the discharge tube.

Between the water inlet opening 17 and the front part 2 of the thrust tube, in which the revolving check valve is mounted, the wall 27 in the Front part of the thrust tube made of elastic material, e.g. B. rubber exist. if after the inflow of water during the explosion, the valve flaps 19 are closed close and a further flow of water is prevented, so cause the Dynamic pressure and the kinetic energy of the water entering the front that the rubber wall 27 inflated, i.e. the kinetic energy is converted into potential energy. This potential stored energy is converted back into kinetic energy at the moment when the flaps or blades of the rotating check valve rise again, which gives the water an additional acceleration for the Receives flowing into the adjoining part of the thrust tube.

As the violent explosions in quick succession in the combustion chamber and the impacts exerted on the water column in the thrust tube the risk of a could cause undesired vibrations of the whole engine and hull, the end of the thrust tube is designed as a damping expansion buffer 28. In this expansion of the ejection tube in front of its exit will also be the one towards the rear outgoing exhaust gases are compressed. In the space between two explosions there is a greater pressure in this buffer space 28 than in the rest of the discharge tube 3. As the water from this buffer pipe: then flows into the open air, the shock occurs heavily damped. In a manner known per se, it sits at the very end of the discharge tube another trumpet-like diffuser 29 which increases the recoil force.

To start the engine, the fuel-air mixture must first be in the combustion chamber 1 are introduced. The hand pump 4 is used for this of the pump piston 30 against the action of the spring 31, the air flows through the pump valve 13 into the pump chamber 4. When you let go of the pump piston, it is released by the The spring 31 is pressed down again, the air flowing through the valve 10 into the combustion chamber 1 is pushed in. When flowing past the carburetor 11, the fast-flowing one tears Air in the usual way with fuels. When pumping in there is @in the carburetor and its float housing 32 has a greater pressure than when sucking. This could different mixtures with different volume ratios of fuel to air develop. To avoid this, it is advisable to pass the pump chamber 4 through a tube 33 to connect to the float housing 32 above its fuel level. This means that there is always the same between the carburetor nozzle and the float housing Pressure difference, regardless of whether the motor is puffing or whether the pump is operating will. So it is the same carburetor setting for sucking in and pumping in usable.

Claims (7)

PATENT CLAIMS: 1. Recoil motor for boat propulsion, in which in a Combustion chamber sucked fillings of a mixture of air and a light and rapidly explosive propellants in succession Explosions ignited and the combustion gases through a one-way non-return valve be let into a thrust tube, which is monitored by a check valve Has a water inlet port and a discharge port, and at which the combustion gases eject the water column in the thrust tube like a piston, characterized in that that the combustion chamber (1) in at least two of each other through check valves (9) separate chambers (7, 8) and with the last chamber in an extension (2) of the thrust tube opens, seen in the direction of travel, behind a venturi tube-like Constriction (18) of the thrust tube is, and that the valve (19, 20, 21), which the The water inlet opening of the thrust tube opens and closes quickly as a low-inertia appealing check valve is designed with butterfly valves that are designed to be radial Axles pivotably mounted blades (19) from one through the water flowing through driven, freely rotating hub (21) carried in the manner of a turbine wheel (16) are. 2. Recoil motor according to claim 1, characterized in that the front Part of the thrust tube between the water inflow opening (17) and the venturi-like Narrowing (18) an elastic acting as a kinetic buffer (compensation buffer) Has wall section (27). 3. Recoil motor according to claim 1 or 2, characterized characterized in that the rear ejection part (3) of the thrust tube serves as an expansion buffer acting extension (28) has. -1. Recoil motor according to claims 1 to 3, characterized characterized in that a hand air pump (4) is attached to the combustion chamber for starting is connected, the cylinder of which is also part of the inlet pipe in continuous operation is for the combustion air, and that the carburetor float housing (32) with the The pressure chamber of the hand air pump (4) is connected by a pressure equalization tube (33). 5. Recoil motor according to claims 1 to 4, characterized in that .that for the ignition an ignition device of the type already proposed is used in the combustion chamber idem in a manner known per se to the terminals of a high-voltage direct current source a high-voltage charge capacitor and two spark gaps behind each other are connected in parallel, one of which causes the discharge when the breakdown voltage is reached of the capacitor and thus also the spark passage on the other, namely, the spark plug (14), and that for the piston-less recoil pulsation motor for boat propulsion now the ignition spark power (current times voltage) at the Spark plug (14) and the inversely proportional thereto, which determines the engine output Spark frequency by adjusting the auxiliary spark gap upstream of the spark plug (38) is regulated. 6. Check valve for flowing media, especially for one System according to claim 1, characterized in that non-return flaps (19) as to Radial axes (20) arranged transversely to the direction of flow are freely pivotable Blades of a freely rotating hub (21) driven by the flowing medium are designed in the manner of a turbine wheel and that the folding axes (20) of this Wings are immediately behind the leading edges (26), so that the wings are at Flow from the front in the direction of flow (valve open) and when Kickbacks in the thrust tube transverse to the direction of flow (valve closed) adjustable are. 7. Recoil motor according to claims 1 and 6, characterized in that the flap blades (19) of the water inlet valve (19, 20, 21) on the thrust tube have a sharpened leading edge (26). Documents considered: German Patent No. 878 599; French Patent Specification No. 1,043,920. U.S. Patent Nos. 2,412,825, 2,714,800.