초록 ▼

The invention relates to a pneumatic percussive tool for a paving breaker and/or a hammer drill comprising a drive piston which is displaceable both backwards and forwards by a crankshaft and arranged in a percussion piston which is displaceable both backwards and forwards. A hollow chamber is conne

The invention relates to a pneumatic percussive tool for a paving breaker and/or a hammer drill comprising a drive piston which is displaceable both backwards and forwards by a crankshaft and arranged in a percussion piston which is displaceable both backwards and forwards. A hollow chamber is connected to a compensating chamber by an idling air channel and embodied between the drive piston and the percussion piston in order to receive a pneumatic spring. A valve is arranged in the idling air channel, the opening and closing position thereof depending on the rotational speed of the crankshaft. If the rotational speed of the crankshaft falls below a predetermined value, the valve opens the connection between the hollow chamber and the compensating chamber so that a pneumatic spring can no longer be to embodied in the hollow chamber and the pneumatic percussion tool is placed in a idling position.

대표청구항 ▼

1. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprising;a drive piston that is moved back and forth by a drive mechanism; a percussion piston that is moved back and forth and that is situated coaxially to the drive piston; a hollow space, formed between t

1. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprising;a drive piston that is moved back and forth by a drive mechanism; a percussion piston that is moved back and forth and that is situated coaxially to the drive piston; a hollow space, formed between the drive piston and the percussion piston, for accommodating an air spring in a percussive operation of the pneumatic spring hammer mechanism; an idling air channel via which the hollow space can be connected with compensating chamber; and a valve situated in the idling air channel, wherein open and closed positions of the valve depend on a frequency of movement of the drive piston. 2. A pneumatic spring hammer mechanism a recited in claim 1, wherein the valve is opened when the frequency of movement of the drive piston falls below a predetermined value, so that a communicating connection arises, via the idling air channel, between the hollow space and the compensating chamber, thereby placing the pneumatic spring hammer mechanism in an idling operating state.3. A pneumatic spring hammer mechanism as recited in claim 2, further comprising a crankshaft that drives the drive piston, wherein the crankshaft is driven by an internal-combustion engine.4. A pneumatic spring hammer mechanism as recited in claim 3, wherein the predetermined frequency of movement of the drive piston essentially corresponds to an idling rotational speed of the internal-combustion engine.5. A pneumatic spring hammer mechanism a recited in claim 1, wherein the frequency of movement of the drive piston is acquired by a sensor device.6. A pneumatic spring hammer mechanism as recited in claim 1, wherein the compensating chamber is one of a crank chamber allocated to the crankshaft and an area surrounding the pneumatic spring hammer mechanism.7. A pneumatic spring hammer mechanism a recited in claim 1, wherein an additional idling device is provided with which, independent of the frequency of movement of the drive piston, the hollow space is brought into communicating connection with one of the compensating chamber and another compensating chamber when the percussion piston moves into a forward axial position, and wherein the connecting communication is effected through the sliding of a tool out of a housing of the pneumatic spring hammer mechanism, thereby placing the pneumatic spring hammer mechanism in an idling state independently of the frequency of movement of the drive piston.8. A pneumatic spring hammer mechanism as recited in claim 7, wherein the additional idling device has at least one idling opening that penetrates a side wall of the drive piston or of the percussion piston.9. A pneumatic spring hammer mechanism as recited in claim 1, wherein the percussion piston has at least one hollow area in which the drive piston is accommodated so as to be capable of axial movement.10. A pneumatic spring hammer mechanism as recited in claim 1, wherein the drive piston has at least one hollow area in which the percussion piston is accommodated so as to be capable of axial movement.11. A pneumatic spring hammer mechanism as recited in claim 1, wherein a hammer mechanism tube is provided in which the percussion piston and the drive piston are guided so as to be capable of axial movement.12. A pneumatic spring hammer mechanism a recited in claim 1, wherein the open and closed positions of the valve depend only on the frequency of movement of the drive piston.13. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprising;a drive piston that is moved back and forth by a drive mechanism; a percussion piston that is moved back and forth and that is situated coaxially to the drive piston; a hollow space, formed between the drive piston and the percussion piston, for accommodating an air spring in a percussive operation of the pneumatic spring hammer mechanism; an idling air channel via which the hollow space can be connected with a compensating chamber; and a valve situated in the idling air channel, wherein open and closed positions of the valve depend on a frequency of movement of the drive piston, wherein the frequency of movement of the drive piston is acquired by a sensor device on the basis of the operating condition of at least one element other than the drive shaft, namely a rotational speed of one of a wobble shaft and a crankshaft of a drive mechanism that drives the drive piston; a rotational speed of a drive motor that drives the drive mechanism; an ignition frequency of an internal-combustion engine that acts as the drive motor; and a power consumption of an electric motor that acts as a drive motor. 14. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprising;a drive piston that is moved back and forth by a drive mechanism; a percussion piston that is moved back and forth and that is situated coaxially to the drive piston; a hollow space, formed between the drive piston and the percussion piston, for accommodating air spring in a percussive of operation of the pneumatic spring hammer mechanism; an idling air channel via which the hollow space can be connected with a compensating chamber; and a valve situated in the idling air channel, wherein open and closed positions of the valve depend on a frequency of movement of the drive piston, wherein the valve is opened and closed depending on a signal of a rotational speed sensor that acquires the rotational speed of a crankshaft of a drive mechanism that drives the drive piston. 15. A pneumatic spring hammer mechanism as recited in claim 14, wherein the valve is controlled via a movable centrifugal weight that is situated on the crankshaft.16. A pneumatic spring hammer mechanism as recited in claim 15, wherein the valve is opened and closed dependent on a position of the centrifugal weight.17. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprisinga housing; a drive piston; a drive mechanism that drives the drive piston back and forth relative to the housing; a percussion piston that is situated coaxially with the drive piston, a hollow space being formed between the drive piston and the percussion piston, the hollow space acting as an air spring during percussive operation, wherein the air spring drives the percussion piston back and forth by transmitting the force of the drive piston to the percussion piston, a compensating air chamber is located in the housing, and an idling air channel is located in the housing, the idling chamber connecting the hollow space to the compensating air chamber; and a valve that is situated inside the idling air channel, the valve opening and closing depending on the frequency of movement of the drive piston. 18. A pneumatic spring hammer mechanism as recited in claim 17, wherein the open and closed position of the valve depends only on the frequency of movement of the drive piston.19. A pneumatic spring hammer mechanism as recited in claim 17, wherein the valve is normally closed and opens whenever the drive piston movement drops below a predetermined frequency.20. A pneumatic spring hammer mechanism for one of a percussive hammer and a drill hammer, comprising;a drive piston that is moved back and forth by a drive mechanism; a percussion piston that is moved back and forth and that is situated coaxially to the drive piston; a hollow space, formed between the drive piston and the percussion piston, for accommodating an air spring in a percussive operation of the pneumatic spring hammer mechanism; an idling air channel via which the hollow space can be connected with compensating chamber; and a means for opening and closing the idling air channel dependent on a frequency of movement of the drive piston.