DK149510B - DRILL AND CHEESE HAMMER WITH COMBUSTION ENGINE DRIVE - Google Patents

Description

in 149510

BACKGROUND OF THE INVENTION The present invention relates to a drill and chisel hairpin with percussion and internal combustion engine having a drive piston in a combustion chamber, wherein the crankshaft of the motor is coupled to a crank which places a percussion piston in the percussion in a reciprocating motion via a pliers rod.

Drill and chisel hammers of the type mentioned above are used above all for major demolition work. Regarding the internal combustion engines used for the drive, these are usually so-called 2-stroke engines. Compared to a 4-stroke engine, these engine designs have the advantage that the design is simpler, and therefore less weight is present at comparable work performance. Therefore, for weight reasons and also for price reasons, the 2-stroke 15 engine is usually used for manually handled appliances and machines.

After each stroke, the 2-stroke engine must be flushed with a gasoline-air mixture, ie the combustion gases contained in the cylinder are displaced by the mixture and the engine is fed with a new flammable mixture. However, in order for the mixture to flow into the cylinder, a pump is required. In virtually all smaller 2-stroke engines, the engine crankcase is used as a flush pump. However, this is associated with a major disadvantage. The locations of crankshaft and connecting rod 25, as well as the cylinder wall, must be adequately lubricated. With the help of the gasoline-air mixture, the lubricating oil is now washed out in a short time, so that the machine without any counter measures is destroyed in a short time. To overcome this disadvantage, a 2-stroke engine uses a benzine-oil mixture. This is the job of the oil to lubricate the drive. Gasoline is an energy carrier for combustion.

However, since the oil which enters the combustion chamber is incompletely incinerated during the combustion of the 2 ^ gasoline-air mixture, it acts as a nuisance, blue out exhaust fume.

In addition, the efficiency of traditional 2-stroke engines is usually less than the efficiency of a comparable 4-stroke engine. The smaller efficiency can mainly be attributed to rinse loss by the flushing of the combustion chamber. For larger, stationary or in-vehicle engines 5, relatively significant costs are used to flush the combustion chamber. Eg. turbo blowers, turntable blowers or piston pumps are known. For portable devices such as e.g. drill and chisel hammers, however, such measures are excluded for weight reasons.

The object of the invention is to provide an internal combustion drill and chisel hammer, whereby the motor achieves a high efficiency due to better rinsing and the hammer in total gains a favorable performance weight.

This is achieved according to the invention in that the percussion cranks are arranged in a space separate from the other parts of the hammer, which space has an intake valve and communicates with the combustion chamber via an outflow opening. leading inlet slots in the engine.

20 When the percussion crank is separated from the other parts of the hammer, it can be used as a flushing pump for the motor. As the percussion volume of a given 2-stroke engine is roughly equivalent to the percussion volume of the percussion, the percussion crate is best suited as a purge pump for the motor. The crankshaft bearing is usually positioned within the engine crankcase and the crank pin is normally lubricated from the percussion. The percussion rod bearings can easily be formed with dense, greased bearings. Therefore, no lubrication of the percussion crank case is required. Since the engine crankcase does not come into contact with the fuel-air mixture of a carburetor or with the aspirated air of an injection engine, the lubrication of the crankshaft jet, the tie rod bearings and the cylindrical guide surfaces of the engine can take place at optimal considerations. Thus, e.g. dip lubrication or oil mist lubrication is used. The aspirated fuel-air mixture must therefore not fulfill any special lubrication functions. Thus, it is possible to operate the apparatus without oily 2-stroke mixture, which has a favorable effect on the operating costs and exhaust gases.

The known 2-stroke machines have another disadvantage. During the flushing, part of the fuel-air mixture, as a flushing loss, flows out into the openings through outflow slots via the silencer. In practice, this cannot be avoided with 2-stroke engines. The consequences of this are high fuel consumption, as part of the fuel does not take part in the combustion process, but constitutes a larger proportion of unburned, mostly toxic gases that escape through the exhaust. With the 15 so-called injection engines, this is avoided by flushing with clean air. As soon as the piston has covered the control slots, and the combustion chamber is thus sealed, fuel is injected by means of a high-pressure injection nozzle. By this measure, three benefits are obtained from the subsequent injection of the fuel, the performance is significantly increased, the fuel consumption is correspondingly reduced and the exhaust gas quality is substantially improved. The flushing according to the invention with the percussion crankcase is suitable for both carburetor engines and injection engines.

25 Through an intake valve · an ignitable mixture is sucked in via a carburetor or carburetor or carburetor or pure air known via an air filter. Although this system is particularly suitable for an internal combustion engine operating on the 2-stroke principle, e.g. also with a 4-stroke engine a so-called charge and thus a performance increase is obtained. The solution according to the invention is particularly simple and uses only an intake valve and a connection line from the outlet chamber's outlet opening to the engine's flow gap compared to a known combustion engine driven drill and chisel hammer. Thus, the inventive measures cause virtually no weight gain.

In order to achieve a simple construction of the apparatus, it is convenient to allow the side facing of the piston rod to form a wall portion of the space separated from the other parts of the barnier. In particular, in the case of a pneumatic percussion, no further measures are needed, since the piston in a cylinder piston is already sealed against the air cushion provided between the drive piston and a piston. The compression of the suction air 10 or mixture within the separated compartment can be optimally determined independently of the drive motor in determining the crank, as well as the dead compartment within certain limits.

By means of a space separated from the other parts of the hammer, new possibilities open up with respect to a known apparatus, 15 in which the percussion of the percussion and the crank of the drive motor are arranged in the same space. In the case of a normal 2-stroke engine, the air-driven tow mixture is sucked into the engine crankcase, and during the combustion chamber's expansion phase, this mixture is subjected to a precompression. inside the crankcase. Shortly before the lower dead point is reached, the overcurrent channels are released by the drive sample and the precompressed mixture can flow into the combustion chamber from the crankcase. However, as the crank continues to rotate, the pressure falls within the crankcase as well as in the overflow duct, thereby delaying the inflow into the combustion chamber. As a result, there is only the possibility of incomplete flushing of the combustion chamber.

On the other hand, if the flush pressure is increased by reducing the crank space, there is a danger that too much of the ignitable mixture will avoid unburning through the exhaust slots 30 as flush loss, which in turn leads to higher fuel consumption. However, in order to optimally adjust the rinsing pressure to the rinsing process, it can be advantageous if the percussion crankshaft is so offset from the crankshaft of the motor that the percussion runs with a cranking angle distance of 10-60 ° 35 after the motor. Hereby, it is possible that from the lower dead center position of the engine crankshaft, by continuing to rotate the crankshaft, a sufficiently large rinsing pressure is present # until the drive piston again uncovers the inflow or overflow slots. Since the percussion is coupled to the 5 crankshaft, this crank angle distance is always the same.

In practice, it has proved convenient if the crank angle is 40 °. Hereby it is achieved that at a given position of the inlet or overflow slots sufficient rinsing pressure is present until the inlet or overflow slits are closed, preventing a backflow of the rinsing air and a far better flushing than was possible with a crankcase rinse. On the other hand, the pressure drop between the flush pressure and the pressure in the combustion chamber is small at the opening of the inflow slot so that a flow can be built up in the combustion chamber and the new inflow mixture can displace most of the combusted gases via the exhaust gaps.

The invention is explained below with reference to the drawing, in which fig. 1 is a partial sectional view of a drill and chisel hammer according to the invention; FIG. 2 shows the drive parts of the percussion and the motor shown in the upper dead center position of the percussion piston, taken in section along line 25 A-A in fig. 1, and FIG. 3 the drive parts in the lower dead center position of the saw piston.

The FIG. 1, the drill and chisel hammer essentially comprises a housing provided with the general reference numeral 1. At the rear end of the housing 1 is attached a handle 2. On the opposite handle 2 is the side of the housing. Seen in 1, a tool holder 3. A rotary motor crankshaft is provided pivotally mounted within the housing 1, which is provided with the general reference numeral 4. A connecting rod 5 is pivotally attached to the crankcase 4a. This connecting rod 5 5 is itself connected to a drive piston 6. The drive 6 of this drive is inserted within a cylinder 1c. At the upper end of the crankshaft 4, a crankshaft provided with the general reference numeral 7 is connected to the crankshaft 4 via a thread 4b. On a crankshaft 7a, a connecting rod 8, 10 is attached to the percussion. This connecting rod 8 is connected to a kind of temple 9 for e.g. a pneumatic percussion. The impact piston 9 is inserted within a cylinder guide 10. The impactor is thus coupled to the internal combustion engine. In the housing I, within the region of the crank 7, there is provided a suction valve which is provided with the general reference number 11. In this suction valve 11, a ball 11a is pressed against a valve seat 11c by means of a spring 11b. Thus, the suction valve 11 has the function of a non-return valve or one-way valve. As the impact piston 9 moves 20 in the direction of the tool holder 3, air or, if necessary, a fuel-air mixture is drawn through the intake valve II into a space 1a, in which the crank 7 and the connecting rod 8 move. This space 1a is sealed to the other parts of the housing 1 by means of a seal 12. The space 1a further has an outlet opening Id. From this outflow opening ld, a pipeline 13 leads to an inflow gap 1b in the cylinder lc. As the piston 9 changes its direction and again moves back toward the handle 2, the space 1a is reduced and the air or fuel-air mixture sucked therein is thereby ejected through the conduit 13. When the piston 6 releases the inflow gap 1a, the air can flow in. in the combustion chamber lb. Hereby, after combustion, the combustion gases which are contained in the combustion chamber 1b are forced out through an exhaust slit 1f.

35 This process is referred to in the professional language as the rinse. In a so-called carburetor engine, flush with a flammable propellant-air mixture. This in itself leads to the disadvantage that part of the mixture can also escape through the exhaust gap 1f, and that the efficiency of the internal combustion engine is reduced. On the other hand, the so-called injection engine is rinsed with clean air. The fuel is first injected into the combustion chamber 1b by means of a nozzle when both the inlet slot 1e and the exhaust gap 1f are closed. This has a favorable impact on efficiency. On the lower end of the crankshaft 4 is a flywheel 14 known in connection with internal combustion engines. This flywheel 14 serves partly 10 to compensate for the output of the internal combustion engine and the power of the engine uptake during the compression phase of the percussion, as well as percussion. In addition, the flywheel is used as a generator to provide the ignition voltage, and as a fan wheel for a cooling air stream which is drawn through a cover 15 and blown past the cylinder 1c.

In the embodiment of FIG. 2 through the apparatus along line A-A in FIG. 1 shows the essential parts of the appliance. The impact piston 9 is here in its upper dead-end position. On the other hand, in relation to the direction of direction D, the drive piston 6 has already exceeded its upper dead center bearing. The percussion column 7a of the percussion is thus set at an angle α with respect to the crankcase 4a of the internal combustion engine, whereby the percussion runs a distance corresponding to this angle α after the internal combustion engine. With the continued rotation of the crank 7, the space 1a is reduced again and the air or air-fuel mixture contained therein is ejected through the outflow opening 1d. The fact that the percussion runs after the combustion engine has, in comparison with a known 2-stroke engine, in which the engine crankcase acts as a flush pump, the advantage that during the entire flushing process the flush pressure is above the pressure in the combustion chamber so that a backflow is avoided.

FIG. 3 shows the same drive parts as in FIG. 2, but in the lower dead center position of the piston 9. Drifstenplet 6 moves 35 here already again away from the crank 7. Hereby the