CN1693034A - Hand machine tool with a hammer mechanism - Google Patents

Abstract

A hand-held power tool equipped with an impact device having an axially reciprocable hammer (1) inside a guide tube (2) with an elastic mechanism for exerting a force on the hammer (1) (4) Via the elastic means the hammer (1) can be moved in the direction of the tool (3) which can be inserted into the hand power tool. The impact device produces a high single impact energy at a relatively small impact frequency, characterized in that the hammer (1) moves against the force of the elastic mechanism (4) after each impact in order to The mechanism is loaded, and the hammer (1) is released suddenly after the elastic mechanism (4) has been loaded, whereby the hammer flies in the direction of the tool (3).

Description

Hand-held power tools with an impact device

technical field

The invention relates to a hand-held power tool, in particular a hammer drill and/or percussion hammer, with a percussion device having an axially reciprocable hammer in a guide tube, wherein there is an elastic force exerted on the hammer A mechanism by which the hammer can be moved in the direction of a tool that can be inserted into the hand power tool.

Background technique

A compression percussion device for electropneumatic hammer drills and/or percussion hammers, which implements repetitive percussion movements, is known from DE 198 10 088 C1 and consists of an eccentric drive, a piston and a hammer. With the aid of these three elements, a rotary motion is converted into an impact motion. The hammer moves axially forward and backward in the guide tube as follows: the piston, which is moved forward by an eccentric drive, seals the air cushion between the piston and the hammer, whereby the hammer is freely inserted into the Knives fly away inside the machine. The hammer transfers its impact energy to the tool, where it receives an impulse in the opposite direction. At the same time, the piston is moved back by an eccentric drive device, thereby forming a certain degree of vacuum in the air cushion between the piston and the hammer. Once the piston has reached its reverse point, and the hammer continues to fly towards the piston, the air cushion between the hammer and the piston is compressed and compressed so that when the piston then moves forward again, the hammer Fly forward towards the knife at a higher speed. In one such compression impact device, the piston and hammer move at the same frequency. A high individual impact energy at a low impact frequency is not possible with this impact device. This also applies to a so-called elastic bow impact device (Federbuegelschlagwerk), as disclosed by EP 544 865 B1. The angle piece made of spring steel is set in an oscillating motion by an eccentric drive, and this spring steel drives the hammer forwards towards the tool or towards a punch arranged between the tool and the hammer. The rebound energy of the hammer will be stored in the elastic bow and released again during the forward movement, as in a pneumatic percussion device.

Contents of the invention

The object of the present invention is to provide a percussion device of the type mentioned at the outset, which can be realized by means of the simplest possible technical measures and with which high individual percussion energies can be achieved at low percussion frequencies.

According to the invention, a hand-held power tool is proposed, in particular a hammer drill and/or percussion hammer, having a percussion device with an axially reciprocable hammer in a guide tube, wherein a counter-hammer A force-applying spring mechanism, by means of which the hammer can be moved in the direction of a tool that can be inserted into the hand-held power tool, wherein there are devices that move the hammer against the force of the spring mechanism after each impact, so that The spring mechanism is loaded and the devices release the hammer suddenly after the spring mechanism has been tensioned, whereby the hammer is driven by the spring mechanism in the direction of the tool.

As a result, the hammer is actively moved against the force of the spring mechanism after each impact, and after being released subsequently receives a high energy for a new impact.

Advantageous structures of the invention can be obtained from the following description.

A suitable driving device for the hammer establishes a force-transmitting connection with the hammer after an impact and moves the hammer against the force of the elastic mechanism, and, once the hammer has reached a certain position, the force-transmitting connection is loosened again.

An advantageous spring mechanism consists of a pressure accumulator filled with a compressible medium, which is located in the guide tube on the side of the hammer facing away from the tool. The accumulator can be filled with a gas, preferably air, or a liquid. The compressible medium - gas or liquid - remains permanently in the pressure accumulator, only a certain leakage loss of the pressure accumulator has to be compensated. For this purpose, a pump can be provided, which supplies a compressible medium to the pressure accumulator in order to compensate leakage losses. The pump output of this pump can be very low, since only leakage losses in the pressure accumulator have to be compensated. Such a lightweight and compact pump can be integrated in a hand-held power tool.

A further advantageous spring mechanism can consist of one or more compression springs and/or tension springs which are supported on the one hand on the hammer and on the other hand on a shoulder which is fixed in the direction of movement of the hammer.

Description of drawings

The invention is explained in detail with the aid of two exemplary embodiments shown in schematic diagrams. Attached are:

FIG. 1 is a longitudinal section through a hammer drill or percussion hammer with a percussion device and a spring mechanism designed as a pressure accumulator.

2 is a longitudinal sectional view of a hammer drill or percussion hammer with a percussion device and an elastic mechanism consisting of a compression spring/tension spring.

Detailed ways

FIG. 1 shows a longitudinal section through a hand-held power tool with an impact device. The hand power tool is, for example, a hammer drill and/or an impact hammer. In the schematic illustration of the hand-held power tool, only the percussion device is shown, which is the solution of the invention. All other functional components normally present in the hand-held power tool are not shown.

The percussion device consists of a hammer 1 in a known manner, which is mounted reciprocally in a guide tube 2 . A tool 3 , for example a drill bit or a drill bit, is inserted in the tool holder of the hand power tool. If the hammer 1 flies forward towards the tool 3 , the hammer transfers its impact momentum to the tool 3 . A punch (not shown) can also be arranged in the guide tube 2 between the tool 3 and the hammer 1 , which transfers the impact momentum received from the hammer 1 to the tool 3 .

The forward movement of the hammer 1 in the direction of the tool 3 inserted in the hand power tool is brought about by a spring mechanism, the force of which acts on the hammer 1 in the direction of the forward movement. In the exemplary embodiment shown in FIG. 1 , this elastic means is a pressure accumulator 4 filled with a compressible medium, which is located in the guide tube 2 on the side of the hammer 1 facing away from the tool. The accumulator chamber 4 is bounded by the side walls of the guide tube 2 , the hammer 1 sliding in the guide tube, and by the rear wall 5 arranged on the guide tube 2 at the end of the guide tube facing away from the tool 3 . A seal 6 is inserted between the hammer 1 and the side wall of the guide tube 2 , which seal prevents the compressible medium from escaping from the accumulator chamber 4 .

The compressible medium can be a liquid or a gas. The accumulator chamber 4 is preferably filled with air. In order to compensate leakage losses in the pressure accumulator 4 , a pump 7 is connected to the pressure accumulator 4 , via which a compressible medium can be supplied to the pressure accumulator 4 for compensating the leakage losses. Since only leakage losses of the compressible medium have to be compensated, a small pump 7 with a low pump power is sufficient, which can be easily installed in the hand-held power tool due to its light weight and small size .

The percussion device has a drive which moves the hammer 1 after each impact against the tool 3 against the force of the spring mechanism and thereby acts on the spring mechanism. The mentioned drive is designed in such a way that it releases the hammer 1 suddenly after the spring mechanism has been loaded, so that the hammer 1 driven by the spring mechanism flies in the direction of the tool. The spring mechanism is not only acted upon by the recoil force of the hammer 1, but is also actively brought to a high tension by means of a separate drive, whereby the hammer 1 acquires a high impact force by releasing the spring mechanism. As a result, very high individual impact energies are produced even at relatively low impact frequencies.

The above-mentioned driving device in the embodiment shown in Figure 1 is explained in detail below:

Connected to the hammer 1 on its side facing away from the tool 3 is a rod 8 extending in the direction of the longitudinal axis of the guide tube 2 and inserted through the rear wall 5 of the guide tube 2 . A seal 9 between the rod 8 and the perforation in the rear wall 5 of the guide tube 2 prevents the compressible medium from escaping from the accumulator chamber 4 . Outside the accumulator, the rod 8 ends in the vicinity of a drive wheel 10 , which is rotatable about an axis perpendicular to the longitudinal axis of the guide tube 2 . The drive wheel is driven in rotation by a shaft 11 of a not shown motor, for example via a spur gear (not shown). Arranged on the drive wheel 10 is a pin 13 which is offset relative to the axis of rotation 12 of the drive wheel and which stands perpendicular to the plane of the drawing from the drive wheel 10 . The end of the rod 8 facing the drive wheel 10 is designed as a hook 14 such that the pin 13 can be moved into the hook 14 within one revolution of the drive wheel 10 . If the hammer 1 is in a backward movement after striking the tool, the rod moves with the hook 14 in the direction of the drive wheel 10 . Here, the pin 13 of the rotating drive wheel 10 slides into the hook 14 and drives the rod 8 with the hammer 1 in the direction of rotation of the drive wheel 10—clockwise in the exemplary embodiment, so that The hammer 1 is moved in the direction of the rear wall 5 of the guide tube 2 and the medium in the accumulator 4 is compressed there. This is followed by a strong increase in the pressure on the hammer 1 in the direction of the tool 3 . As soon as the drive wheel 10 has rotated half a turn and thus the pin 13 has reached a position 13 farthest from the guide tube 2 , the pin 13 slides out of the hook 14 again. At this moment, the hammer 1 is released and, driven by the pressure of the accumulator 4 , it moves in the direction of the tool 3 to form a new impact. The speed of rotation of the drive wheel 10 can be adjusted such that the hook 14 at the end of the rod 8 is always just above the pin 13 of the drive wheel 10 when the hammer 1 is in the reciprocating motion again after an impact.

Instead of a drive that pulls the hammer 1 via the rod 8 against the force of the spring mechanism, it is also possible to provide a drive that pushes the hammer 1 against the force of the spring mechanism. The drive can then be arranged on the side of the hammer 1 facing the tool. Instead of the exemplified drive for the hammer 1 , it is also possible to use any other mechanism which moves the hammer 1 against the force of the spring mechanism after each individual stroke of the hammer in order to tension the spring mechanism.

FIG. 2 shows a schematic cross-section of a hand-held power tool in which the elastic mechanism is not formed by a pressure accumulator, as in the embodiment in FIG. 1, but one or more tension springs and/or or compression springs. Apart from the spring mechanism, all other functional elements are identical to the above-described embodiment of FIG. 1 and are provided with the same reference numerals in FIG. 2 as in FIG. 1 .

As shown in Figure 2, in the cavity of guide pipe 2, a pressure spring 15 is installed between hammer 1 and the rear wall 5 of guide pipe, and this pressure spring is supported on the rear wall 5 of guide pipe 2 on the one hand, on the other hand On the one hand, it is supported on the hammer 1 . As an alternative or in addition to the compression spring 15 , a tension spring 16 can also be provided on the side of the hammer 1 facing the tool 3 . The tension spring is connected on the one hand to the hammer 1 and on the other hand to a shoulder of the guide tube 2 . Instead of only one compression spring and/or one tension spring, it is also possible to use a plurality of compression springs and/or tension springs which impart the required impact force to hammer 1 .

Claims (5)

1. hand held power machine, especially hammer drill and/or jump bit have a percussion mechanism, this percussion mechanism has an axial reciprocating hammer (1) in a guide pipe (2), and an elastic mechanism (4,15 that hammer (1) is applied power is wherein arranged, 16), can make this hammer (1) towards the direction motion that can be inserted in the cutter (3) in the hand held power machine, it is characterized in that by it, has device (8,10,13,14), these devices make hammer (1) impact the back against elastic mechanism (4 at every turn, 15,16) power motion is so that load this elastic mechanism, and these devices (8,10,13,14) at elastic mechanism (4,15,16) suddenly discharge this hammer (1) after the tensioning again, thus, this is hammered into shape at elastic mechanism (4,15,16) move towards the direction of cutter (3) under the driving and fly to.

2. according to the hand held power machine of claim 1, it is characterized in that these devices (8,10,13,14) form by a drive unit, this drive unit is set up one with hammer (1) and is transmitted being connected of power after hammer applies one-shot, and make of the power motion of this hammer against elastic mechanism (4,15,16), in case should the hammer (1) at it against elastic mechanism (4, arrived a definite position in the motion of power 15,16), this drive unit unclamps the connection of this transmission power again.

3. according to the hand held power machine of claim 1 or 2, it is characterized in that this elastic mechanism (4,15,16) is made up of a pressure accumulating chamber (4) that is full of compressible medium, this pressure accumulating chamber is in guide pipe (2) on the side that deviates from cutter (3) of hammer (1).

4. according to claim 3 hand held power machine, it is characterized in that this pressure accumulating chamber (4) can be by a pump (7) input compressible medium.

5. according to claim 1 or 2 hand held power machines, it is characterized in that, this elastic mechanism (14,15) form by one or more compression springs (15) and/or tension spring (16), these springs are supported on the hammer (1) on the one hand, be supported on one on the other hand on the fixing convex shoulder (5,17) on this hammer direction of motion.