SE436989B - COMBUSTION ENGINE DRIVER AND GAMBLE HAMMER WHERE THE ENGINE'S WEB HOUSE IS SEPARATED FROM THE SEAT HOUSE HOUSE - Google Patents

Description

7906633-8 flushing loss during flushing of the combustion chamber. For larger, stationary or in-vehicle engines, a considerable cost is added for the performance of the combustion chamber. For example, turboblowing machines, turntable blowing machines or also piston pumps are known in the past. In portable devices, such as drilling and chisel hammers, however, such measures are excluded for weight reasons.

The object of the present invention is to provide a drill and chisel hammer with an internal combustion engine, in which the engine, thanks to good flushing, achieves a high efficiency and the hammer as a whole has a favorable power weight.

According to the invention, this object is solved by arranging the crank length of the percussion device in a space separated from the other parts of the hammer, which has an inlet valve and is connected via an outflow opening to inlet slots leading to the engine combustion chamber.

When the percussion chamber's crankcase is separated from the rest of the hammer, it can be used as a flushing pump for the engine. Since the percussion unit's percussion volume for a given two-stroke engine roughly corresponds to the engine's percussion volume, the percussion crankcase is best suited as the engine's coil pump. The crankshaft bearing is usually arranged in the engine crankcase and the drive piston is lubricated in the usual way by the percussion instrument.

The percussion unit's connecting rod bearings can be designed without problems with tight, grease-lubricated bearings. Lubrication of the percussion crankcase is therefore not necessary. When the engine crankcase at a carburettor engine does not come into contact with the fuel-air mixture or with the intake air at an injection engine, the lubrication of the engine crankshaft bearings, connecting rod bearings and cylinder liner surface can be optimally designed. Thus, e.g. a dip or oil mist lubrication is used. The intake fuel-air mixture thus has no special lubrication functions to fulfill. It is thus possible to operate the appliance without an oily two-stroke mixture, which has a favorable effect on operating costs and exhaust gases.

The previously known two-stroke machines have another disadvantage. During flushing, part of the fuel-air mixture flows as flushing loss through the outlet slot over the exhaust peak into the open air. This can practically not be prevented with two-stroke engines. The result is a high fuel consumption, since this fuel does not participate in the combustion process as well as in a high proportion of unburned, mostly toxic gases, which are emitted through the exhaust pipe. With the so-called injection motors, this is prevented by flushing with clean air.

As soon as the piston covers the guide slot and the combustion chamber is thus tight, fuel is injected by means of a high-pressure injection nozzle. Through these measures, three advantages are obtained: through this later injection of the fuel, the effect is noticeably increased, the fuel consumption is reduced in a decisive way and the exhaust gas quality is significantly improved. The flushing according to the invention with the percussion crankcase is suitable for both carburettor and injection engines.

A flammable mixture is sucked in through the inlet valve via a gasifier known per se per se or pure air is sucked in over an air filter. Even if this system is particularly suitable for a combustion engine operating according to the two-stroke principle, a so-called pre-compression can thus also be obtained with a four-stroke engine, for example.

The solution according to the invention is extremely simple and, in relation to a conventional, hammer and chisel hammer driven by an internal combustion engine, requires only an inlet valve as well as a connecting line between the outflow opening in the separated space to the engine inlet slots. The measures according to the invention thus entail practically no weight gain.

For a simple construction of the apparatus, it is suitable that the rear side of the drive piston facing the connecting rod forms a wall part of the space separated from the other parts of the hammer. In the case of a pneumatic percussion device in particular, no further measures are required at all, since the drive piston reciprocating in a cylinder is already sealed against the air cushion arranged between the drive piston and a percussion piston. The compression of the intake air or the mixture in the divided chamber can be optimally determined independently of the drive motor by determining the crank stroke as well as the dead space within certain limits.

A room separate from the other parts of the hammer offers new possibilities in relation to a previously known device, in which the crankcase's crankcase and the drive motor's crankcase are arranged in the same chamber. In a conventional two-stroke engine, the air-fuel mixture is sucked into the engine crankcase and pre-compressed during the combustion chamber expansion phase in the crankcase. Shortly before reaching the lower dead center, the overflow channel is released from the piston and the pre-compressed mixture can flow from the crankcase into the combustion chamber. With continued rotation of the crank length, however, the pressure in the crankcase as well as in the overflow channel decreases again, so that the inflow into the combustion chamber slows down. For this reason, only an incomplete flushing of the combustion chamber is possible. If, on the other hand, the flushing pressure is increased by a reduction of the crankcase, there is a risk that too large a part of the ignition mixture as flushing loss goes out unburned through the exhaust slot, which in turn leads to an increased fuel consumption. In order to now be able to optimally adapt the flushing pressure to the flushing process, it is favorable if the crankcase's crankshaft is displaced to the engine's crankshaft so that the striker goes after the engine with a crankshaft displacement of 10 - 60 °. Thereby it is possible, on the basis of the lower dead center position of the engine piston, in the event of further rotation of the crankshaft to maintain a sufficient coil pressure until the inlet or overflow slots are again covered by the piston. When the percussion is coupled to the crankshaft, this crankshaft displacement always remains the same.

In practice, it has proved expedient to have a crankshaft displacement of 400. This ensures that at a given position of the inlet or overflow slots, a sufficient flushing pressure prevails until the inlet or overflow slots are closed, which prevents a backflow of the flushing air and enables a wide flush air. better flushing than can be obtained with a crankcase flush. Furthermore, when the inlet slot is opened, the pressure drop between the purge pressure and the pressure in the combustion chamber is small, whereby a flow can be formed in the combustion chamber and the newly flowing mixture displaces the combusted gases for the most part through the exhaust slots. The invention is described in more detail below in connection with the drawings showing an embodiment, in which Fig. 1 shows a drill and chisel hammer according to the invention, partly in section, Fig. 2 shows the driving parts of the percussion device and the engine in the drive piston. upper dead center position, corresponding to the line A - A in Fig. 1, and Fig. 3 shows the driving parts in the lower dead center position of the drive piston.

The hammer and chisel hammer shown in Fig. 1 essentially consists of a housing generally denoted by 1. Attached to the rear end of the housing 1 is a handle 2. On the side of the housing 1 opposite the handle 2, a tool holder 3 is arranged.

The housing 1 of the internal combustion engine with 4 crankshafts is rotatably mounted. A connecting rod 5 is rotatably attached to a crank arm 4a. The connecting rod 5 is also connected to a piston 6. The piston 6 is in turn controlled in a cylinder 1c. At the upper end of the crankshaft 4, a crank length generally designated 7 is connected to the crankshaft 4 over a thread 4b. A connecting rod 8 in the percussion device is attached to a crank pin 7a. The connecting rod 8, in turn, is reconnected to a drive piston 9, for example for a pneumatic percussion instrument. The drive piston 9 is controlled in a guide sleeve 10. The percussion unit is thus connected to the internal combustion engine. An inlet valve 11 is arranged on the housing 1 in the area of the crank hose 7. In the inlet valve 11, a ball 11a is pressed by means of a spring 11b against a valve seat 11c. The inlet valve 11 is thus a non-return or one-way valve. When the drive piston 9 moves in the direction of the tool holder 3, air or possibly an fuel-air mixture is sucked in through the inlet valve 11 into a space 1a in which the crank length 7 and the connecting rod 8 move. The room 1a is sealed against the other parts of the housing 1 by a seal l2. Room la further has an outlet opening ld. A pipeline 13 leads from the outlet opening 1d to an inlet slot 1c in the cylinder 1c. When the drive piston 9 changes its direction and again moves towards the handle 2, the space 1a is reduced and the air sucked in it or the fuel-air mixture is expelled through the pipeline 13. When the piston 6 leaves the inlet slot le free, the air can flow into the combustion chamber 1b. In this case, the combustion exhaust gas contained in the combustion chamber 1b after the ignition is displaced out through an exhaust slot 1f. This process is referred to in technical terms as flushing. In a so-called carburettor engine, flush with a combustible fuel-air mixture. This has the disadvantage that a part of the mixture can also pass out through the exhaust slot lf and thereby lower the efficiency of the internal combustion engine. In so-called injection engines, on the other hand, it is flushed with clean air. Only then is the propellant injected through a nozzle into the combustion chamber 1b, when both the inlet slot 1e and the exhaust slot 1f are closed.

This affects the efficiency in a favorable direction. At the lower end of the crankshaft 4, a flywheel 14 common to internal combustion engines is arranged. The flywheel 14 functions on the one hand for equalization between the power output of the internal combustion engine and the power consumption of the engine during the compression phase as well as the percussion work of the percussion device. In addition, the flywheel acts as a generator for generating the ignition voltage and as a fan wheel for generating a cooling air stream, which is sucked in through a cover 15 and blown past the cylinder 1c.

The section through the device along the line A - A in Fig. 1 shown in Fig. 2 shows the essential drive parts of the apparatus. The drive piston 9 is then in its upper dead center position. In relation to the direction of rotation D, on the other hand, the piston 6 has already exceeded its upper dead center position. The crank pin 7a in the percussion unit is thus displaced in relation to the crank arm 4a of the internal combustion engine by an angle C1, the percussion unit going after the internal combustion engine at this angle DK. Upon further rotation of the crank length 7, the space 1a is reduced again and the air or air-fuel mixture contained therein is expelled through the outflow opening 1d. This phase difference between the percussion instrument and the internal combustion engine has, in comparison with an ordinary two-stroke engine, where the engine crankcase acts as a purge pump, the advantage that during the entire purge process the purge pressure is above the pressure in the combustion chamber, so that backflow is prevented.

Fig. 3 shows the same driving parts as in Fig. 2, but in the lower dead center position of the drive piston 9. The piston 6 then again moves away from the crank length 7. In this case it is compressed from the space 1a through the outflow opening 1d and the inlet slot 1e 790663: -a 7 entering the fuel-air mixture entering the combustion chamber.

In this position, the power requirement of the percussion instrument is small. The energy stored in the flywheel can thus be practically completely used for compression of the fuel-air mixture enclosed in the combustion chamber 1b. It follows that the phase shift between percussion and internal combustion engine is very favorable.

Claims (4)

7966633-e 8 Patent Claims 1. l. Drill and chisel hammer with percussion and internal combustion engine, the engine crankshaft being connected to a crank hose, which over a connecting rod puts the percussion drive piston in a reciprocating motion, characterized in that the percussion crank (7 ) is arranged in a separate compartment (1a) in relation to the other parts of the hammer, which has an inlet valve (11) and which, via an outflow opening (1d), communicates with inlet slots (1e) leading to the engine combustion chamber (1b). Drill and chisel hammer according to claim 1, characterized in that the rear side of the drive piston (9) facing the connecting rod (8) forms a wall part of the space (1a) separated from the other parts of the hammer. Drill and chisel hammer according to Claim 1 or 2, characterized in that the crank length (7) of the percussion device is so offset against the crankshaft of the motor (4) that the percussion device ° in relation to the motor is phase-shifted with a crank length displacement of 10 - 6 ° C. 7 Drill and chisel hammer according to claim 3, characterized in that the crank length displacement amounts to 4o °.