EP2310171B1 - Striking mechanism with a variable rotatory drive - Google Patents

Description

The invention relates to a striking mechanism according to the preamble of claim 1 and 2.

Such impactors are e.g. used in electrically operated break hammers or drills and / or impact hammers. The striking mechanisms usually have a motor rotating in a direction of rotation at a substantially constant rotational speed, which reciprocates a drive piston (piston) via a crank or wobble drive, which in turn is driven by a spring, e.g. an air spring drives a percussion piston (bat).

For impact gears driven by a rotating motor, the stroke of the drive piston is fixed due to the specified geometry of the crank mechanism (crank radius) or the wobble mechanism (wobble stroke). The rotational frequency is usually largely constant during a beating cycle due to the inertia. By the stroke of the drive piston and the rotation frequency, the impact strength is fixed. Thus, the frequency and impact strength can not be set independently.

From the EP 1 172 180 A2 is known a striking mechanism, which is driven by a rotating electric motor. The stroke of the drive piston can be changed manually or by an electric motor via an adjustment system. However, the effort for the adjustment is high. Moreover, the adjustment mechanism can not react to different recoil conditions within one beat cycle.

In addition, from the DE 10 2005 030 340 B3 and the WO 03/066286 A1 Schlagwerke known in which the drive of the drive piston is directly via an electrically operated linear motor. The linear motor offers the possibility of individually changing each cycle of impact cycles within certain physical limits. The disadvantage, however, is that runners and stator are not fully engaged with their respective length at any time as they pass linearly past each other. This means that the structural complexity and thus the costs and the engine weight are greater than with a rotating engine, in which the entire electromagnetic active surface is always engaged.

From the EP-A-1 607 186 , which is based on the two-part version of claims 1 and 2, a percussion is known in which the Einzetschtagenergie can be controlled. For this purpose, a speed control is provided, with which the engine speed is variable.

In the DE 498 728 C a percussion mechanism is described in which a rocking lever can be reciprocated about an axis of rotation when an iron core attached to the rocker arm is attracted by two opposing magnetic coils accordingly. Characterized a reciprocating motion of a coupled to the rocker arm via a leaf spring striker is effected, which in turn acts on a chisel.

The invention has for its object to provide a striking mechanism with a drive in which during the period of a single stroke cycle, a control of the way and speed of the drive piston and thus the stroke is possible. In addition, the beat frequency and impact strength should be variably adjustable from beat cycle to beat cycle.

The object is achieved by a striking mechanism with the features of claim 1 or 2. Further developments are specified in the dependent claims.

A striking mechanism according to claim 1, comprising a drive with a motor and a rotor provided in the motor, a drive element which can be moved back and forth by the drive in a guide device, a striking element and with a coupling device acting between the drive element and the striking element, via which the movement of the drive element is transferable to the striking element, is characterized in that the motor is controlled such that within a stroke cycle changeable, so different rotational speeds of the rotor can be generated.

By this particular control of the motor, it is possible, in each case a certain, e.g. to achieve by a control predetermined single impact energy. By driving the motor so precisely that the rotor will have different rotational speeds, even within one beat cycle, and e.g. can achieve a special motion profile, accordingly, a default for the movement of the drive element coupled to the rotor can be achieved. As a result, the duration, the stroke, the frequency and overall the travel-time behavior of the rotor, of the drive element and finally also of the striking element can be predetermined or controlled.

The motor is controllable such that a change in the rotational speed is effected within a beating cycle in accordance with a predetermined algorithm for the movement of the rotor. For example, the algorithm may have a fixed path-time profile for the movement of the rotor by a controller and / or regulation. In this case, therefore, the movement of the rotor and subsequently the drive element is predetermined over time, eg only in dependence on external specifications of the operator.

Of course, the path-time history can change from beat cycle to beat cycle. So it is e.g. possible at a start of the percussion initially automatically soft start with relatively small stroke of the drive element, but already to achieve high operating frequency, even if the operator already operates a corresponding control element as if he wanted to operate the device at full load.

The fixed path-time course can thus be variable depending on a change in the environmental conditions (in particular the wishes of the operator).

The algorithm dictates movement of the rotor in response to events occurring on or with components of the percussion mechanism, particularly in response to actual movement of the striking element. In this case, e.g. the movement of the striking element can be monitored by suitable means so that the movement of the rotor and subsequently of the driving element adapts to the striking element. If e.g. the impact element is repelled only by a small recoil, the drive element can perform a corresponding stroke to suck the striker back again.

The motor of the impact mechanism according to claim 2 is to be controlled such that the motor generates a reciprocating motion within a beat cycle.

Due to the special design of the motor and its control, it is thus possible that the motor does not perform a constant rotational movement. Rather, the rotational movement of the rotor with respect to the rotational speed, the frequency but also the direction of rotation can be variably and individually controlled, even from beat cycle to beat cycle or even within a beat cycle. This is understood as a beat cycle, the period from one beat to the next.

So it is e.g. It is also possible that the rotor does not necessarily reach a direction of the same direction but a reciprocating movement. Thus, it may be useful if the motor is able to produce both a co-rotation and a reciprocating motion. The motor can then either run in the same direction in one direction or, if necessary, a reciprocating motion, e.g. around bottom dead center. This requires high variability and controllability from the engine.

For this purpose, it makes sense if the motor is designed to be very low in inertia, so that the rotational movement of the motor and the derived movement of the drive element can be approximated to the course of movement of the striking element. It has been found that, in particular, a harmonic stroke sequence can be achieved if the distance between the drive element and impact element during a stroke cycle is not too large. Thereby, the coupling device effective between the drive element and the striking element, e.g. an air spring to be built with a smaller size, in particular shorter.

It may be appropriate to control the motor so that the bottom dead center is always, ie traversed at each stroke cycle, since the impact point for all conceivable impact strengths and frequencies is always approximately in the same place. As a result, all installation space or energy expenditures for braking the piston at bottom dead center are eliminated. In particular, no lower return air spring or the provision of electrical braking energy is required, as is the case with a linear drive. (see. DE 10 2005 030 340 B3 ).

The theoretical potential top dead center does not necessarily have to be passed through in this mode by the drive element, because the drive element already reverses its direction of movement.

For a maximum impact strength, so at full load of the engine, it may be appropriate to maintain the sense of rotation for top dead center. As a result, especially in a cycle with high power requirements, the energy expenditure for braking the piston at top dead center is lower. Similar to the bottom dead center then only a small or no reversing air spring and low electrical braking energy is required at top dead center. A transmission device can be provided between the motor and the drive element for transmitting a rotational movement generated by the motor into a longitudinal movement of the drive element. The transmission device may have suitable components, such as crank mechanism, connecting rod, rack (even with uneven pitch), scenery, cam, worm, wobble, space gear, chain, timing belt, cable drive, etc.

The transmission device may have a translation device, such that the motor generates several revolutions of the rotor during a beat cycle. The motor then travels several turns in the same direction during one beat cycle until the engine rotational direction is reversed at top dead center or near top dead center of the drive element. In this design, the motor must be suitable for an increased speed. For this he only has to provide a lower torque so that it is possible to make the engine smaller.

Alternatively, such a translation device, e.g. be dispensed with a transmission intermediate stage to keep the inertial forces low.

The motor may e.g. as an asynchronous motor or as a synchronous motor, e.g. be designed as a magnetic motor, claw pole motor or torque motor.

From the basic control ago, the drive then corresponds to a linear motor, such as in the WO 03/066286 A1 or the DE 10 2005 030 340 B3 is described. However, in the present case, the motor is a rewound, that is to say functionally closed linear motor, with a rotor driven in rotation instead of an axially movable rotor in a linear motor.

In one variant, the drive can have two motors operated in opposite directions, which jointly drive the drive element. In this embodiment, it is sufficient to couple together two relatively small-sized, weak motors that move together the drive element. The division of the drive into two motors increases the latitude in the design of a working implement using the striking mechanism, e.g. a departure hammer.

Each of the motors can in turn be individually controlled in the manner described above within a beating cycle and, for example, as a magnetic motor or Synchronous motor be formed so that on the one hand has a rotating rotor and on the other hand can be controlled as a linear motor.

Each of the motors can be assigned a transmission device in order to transmit the rotational movement generated by the respective motor into a longitudinal movement of the drive element. It is also possible that the motors act on a common transmission device.

The motors may also be coupled together in some other way to jointly drive the drive member.

In one embodiment, the striking mechanism is an air spring impact mechanism, the drive element designed as a drive piston and the striking element as a percussion piston. The coupling device may have a formed in a cavity between the drive piston and the percussion piston driving air spring, via which the movement of the drive piston is transferable to the percussion piston.

In a further development, in addition to the drive air spring, the coupling device may have a return air spring effective between the drive piston and the percussion piston in order to assist a backward movement of the percussion piston after a blow. In this way, a so-called double-acting air spring is realized.

Compared to a conventional rotary motor, such as in EP 1 172 180 A2 described, the invention allows a variation of the beat frequency regardless of the variation of impact strength. As a result, for example, a high impact frequency can be achieved with a small impact strength when applying a chisel acted upon by the impact mechanism in a hammer. Idling can be achieved by quickly decelerating the engine without requiring an idle or special idler. In addition, an exact impact strength control is possible even with a wide variety of recoil (the impact of the impact element on the tool) by adjusting the movement of the drive piston to the flight curve of the impact element. The ratio between drive element and impact element can be adjusted depending on different ambient pressures.

There are also advantages over electrodynamic drives with a linear motor. Thus, the rotor and stator surfaces are fully utilized, because rotor (rotor) and stator are always fully engaged. They are not or only weaker Reversing springs near the top and bottom dead centers require the drive piston to decelerate because the approximate position of the return points of the drive piston are approximately equal to the top dead center and bottom dead center of the engine during a full stroke.

Due to the design lower electrical forces and thus small measures for electrical intermediate storage are possible, so that e.g. smaller capacitors can be selected.

The motor is easier to seal due to the rotationally moving parts and the rotation bearings therewith, than is required for linear motors with linear guide of a rotor. The bearing point of the rotor must - since radially inwardly - record only a lower speed than is the case with the rotor of a linear motor. This reduces mass forces and friction.

Fig. 1

in schematischer Darstellung ein erfindungsgemäßes Schlagwerk;

Fig 2

den Bewegungsverlauf eines Antriebskolbens und eines Schlagkolbens bei einem bekannten Schlagwerk;

Fig. 3 bis 5

verschiedene Bewegungsverläufe des Antriebskolbens über dem Kurbelwinkel;

Fig. 6

Bewegungsverläufe des Antriebskolbens über der Zeit;

Fig. 7

die Bewegung von Antriebskolben und Schlagkolben bei dem Schlagwerk von Fig. 1; und

Fig. 8

eine andere Ausführungsform des Schlagwerks.

These and further advantages and features will be explained in more detail below by means of examples with the aid of the accompanying figures. Show it:

Fig. 1

a schematic representation of an impact mechanism according to the invention;

Fig. 2

the course of movement of a drive piston and a percussion piston in a known striking mechanism;

Fig. 3 to 5

different courses of movement of the drive piston above the crank angle;

Fig. 6

Movement patterns of the drive piston over time;

Fig. 7

the movement of drive piston and percussion piston in the striking mechanism of Fig. 1 ; and

Fig. 8

another embodiment of the percussion mechanism.

Fig. 1 shows a schematic side view of an impact mechanism with a motor 1, which has a stator 2, a rotor 3 and an electronic control unit 4. The motor is designed as a magnetic motor or synchronous motor. It thus corresponds in effect to a circumferentially closed, wound linear motor. The Control electronics 4 makes it possible to generate any rotational movements, paths and rotational speeds of the rotor 3 within physical limits.

The rotational movement of the rotor 3 is transmitted via a pin 5 to a connecting rod 6. The pin 5 and the connecting rod 6 form a transmission device in the form of a crank mechanism.

With the connecting rod 6 serving as a drive element drive piston 7 is coupled, which is within a serving as a guide device guide cylinder 8 back and forth.

Within the drive piston 7 serving as a striking element percussion piston 9 is arranged. The percussion piston 9 is reciprocable in a cavity of the drive piston 7. As a result of the relative movement between the drive piston 7 and the percussion piston 9, a drive air spring 10 is formed in a known manner, which also moves the percussion piston 9 forward in particular in the event of a forward movement of the drive piston 7 in the direction of a chisel 11. The percussion piston 9 strikes cyclically on the chisel 11, which is held in a tool holder 13.

In addition, a return air spring 12 is also formed in front of the percussion piston 9 in the interior of the drive piston 7, which supports the return movement of the percussion piston 9 after completed blow. As a result, a percussion is realized with a known double-acting air spring.

Fig. 2 shows the movement of the drive piston (piston) over the crank angle for a conventional percussion device with a rotary drive ( Fig. 2a ) as well as the movement of the drive piston and the percussion piston (racket) over time ( Fig. 2b ).

Thus, it can be seen that the electric motor sweeps over a rotation angle of 360 ° during a beating cycle and the drive piston performs a corresponding approximate sine movement in the piston stroke. In Fig. 2 Two impact cycles are shown (rotation angle 720 °).

In Fig. 2b It can be seen that the club (lower curve) follows the movement of the piston with a time lag. The blow takes place in the lowest position.

In contrast to these achievable with conventional electric motors in a conventional manner trajectories, the invention makes it possible in the in Fig. 1 shown Schlagwerk the drive piston individually variable to control, as in the Fig. 3 to 6 shown.

Fig. 3 shows the piston movement of the drive piston 7 above the crank angle. The piston stroke between the maximum possible top dead center (1.0000) and bottom dead center (0.0000) is fully utilized.

In the presentation of Fig. 4 Although the drive piston reaches the bottom dead center at 0.0000, but he does not reach the maximum top dead center of Fig. 3 , but only reached a top dead center (here: reversal point) in the range of 0.8000.

at Fig. 5 the motor 1 is controlled such that the drive piston reaches a top dead center of only 0.3500 and then reversed again.

The in the Fig. 3 to 5 Gradients shown are achieved by means of the motor 1, characterized in that in each case upon reaching the corresponding maximum angle of rotation, the direction of rotation of the rotor 3 is reversed. Thus, the drive piston 7 performs a reciprocating motion, without that of the transmission device, ie, for example, the crank drive predetermined maximum stroke and the maximum top dead center (as in Fig. 3 shown) must be passed through.

It only makes sense if the bottom dead center (pos. 0.0000) is traversed during each stroke cycle, as well as in the Fig. 3 to 5 shown.

These piston movements are in Fig. 6 applied over time.

It is clearly recognizable that the drive piston can achieve very different courses of motion, piston strokes and frequencies, which is made possible by the respective actuation of the motor 1. For example, in the relatively small piston stroke of Fig. 5 high frequency hitting is possible over time, while at the exhaustion of the maximum possible piston stroke ( Fig. 3 ) a lower frequency is achieved.

In addition, it can be seen that it is not necessary for the generation of the impact movement of the drive piston 7 that the drive piston must be moved through the maximum top dead center (item 1,0000).

Alternatively to the in the Fig. 3 to 5 In embodiments shown, it is also possible that the bottom dead center is not traversed during each stroke cycle. In this case, the direction of rotation of the rotor 3 and thus the direction of movement of the drive piston can already be reversed before the crank drive (or a corresponding rack and pinion drive etc.) or the drive piston have reached the theoretically possible bottom dead center. The drive piston is then initially moved downward by the rotation of the rotor 3, but is decelerated and moved back even before the (theoretically possible) bottom dead center is reached. In this way, the bottom dead center is not traversed in this embodiment, analogous to the top dead center in connection with the embodiments of Fig. 3 to 5 applies. The reciprocating motion of the rotor 3 causes a reciprocating motion of the drive piston without passing through the lower or top dead center.

Fig. 7 shows an example of the movement of the drive piston 7 and the percussion piston 9 over time.

In contrast to the piston-racket movement in a known striking mechanism, as in Fig. 2b shown, the course of movement of the drive piston and the percussion piston 9 are clearly approximated. The axial distance that can be maximally achieved is considerably lower than in the prior art. As a result, for example, the drive air spring 10 can be made shorter.

Fig. 8 shows another embodiment of the percussion of Fig. 1 ,

Here, two motors 1 are provided, each driving a connecting rod 6, whereby the drive piston 7 is reciprocated in the appropriate manner. The motors 1 are operated in opposite directions, as shown by the arrow.

The changing engine torques cancel each other, so that no lateral forces and no tilting moments act on the drive piston 7. This increases the smoothness and thus the comfort when the percussion, e.g. is used in a hand-held implement.

The percussion can be used in particular in a drill and / or percussion hammer or a breaker.

Claims (15)

1. Percussion mechanism, comprising:

   - a drive with a motor (1) and a rotor (3) provided in the motor (1);

   - a drive element (7) which can be moved in a reciprocating manner in a guide unit (8) by the drive;

   - a percussion element (9); and comprising

   - a coupling device (10) which is operative between the drive element (7) and the percussion element (9) and by means of which the movement of the drive element (7) can be transferred to the percussion element (9);
   characterised in that

   - the motor (1) can be controlled in such a manner that variable rotational speeds of the rotor (3) can be generated within one percussion cycle; and that

   - the motor (1) can be controlled in such a manner that a change in the rotational speed is effected within one percussion cycle corresponding to a specified algorithm for the movement of the rotor (3); and that

   - the algorithm specifies a movement of the rotor (3) as a function of events which occur on or with components of the percussion mechanism, in particular as a function of an actual movement of the percussion element (9).
2. Percussion mechanism, comprising

   - a drive with a motor (1) and a rotor (3) provided in the motor (1);

   - a drive element (7) which can be moved in a reciprocating manner in a guide unit (8) by the drive;

   - a percussion element (9); and comprising

   - a coupling device (10) which is operative between the drive element (7) and the percussion element (9) and by means of which the movement of the drive element (7) can be transferred to the percussion element (9);
   wherein

   - the motor (1) can be controlled in such a manner that rotational speeds of the rotor (3) which can vary from percussion cycle to percussion cycle can be generated;
   characterised in that

   - the motor (1) can be controlled in such a manner that the motor (1) generates a reciprocating rotational movement of the rotor (3) within one percussion cycle.
3. Percussion mechanism as claimed in claim 2, characterised in that the motor (1) can be controlled in such a manner that a change in the rotational speed is effected within one percussion cycle and/or from percussion cycle to percussion cycle corresponding to a specified algorithm for the movement of the rotor (3).
4. Percussion mechanism as claimed in any one of claims 2 or 3, characterised in that the algorithm specifies a movement of the rotor (3) as a function of events which occur on or with components of the percussion mechanism, in particular as a function of an actual movement of the percussion element (9).
5. Percussion mechanism as claimed in any one of claims 1 to 4, characterised in that the algorithm has a displacement-time curve, which is fixedly specified by a control and/or regulating facility, for the movement of the rotor (3).
6. Percussion mechanism as claimed in any one of claims 1 to 5, characterised in that the motor (1) can be controlled in such a manner that the drive element (7) which is driven by the motor (1) achieves a path of movement which is approximated to the path of movement of the percussion element (9).
7. Percussion mechanism as claimed in any one of claims 1 to 6, characterised in that the motor (1) can be controlled in such a manner that

   - a lower dead centre of the drive element (7), located towards the percussion element (9), is traversed within each percussion cycle; and/or that

   - an upper dead centre of the drive element (7), located remotely from the percussion element, is not traversed within each percussion cycle.
8. Percussion mechanism as claimed in any one of claims 1 to 7, characterised in that a transfer device (5, 6) is provided between the motor (1) and the drive element (7) for transferring a rotational movement generated by the motor (1) into a longitudinal movement of the drive element (7).
9. Percussion mechanism as claimed in any one of claims 1 to 8, characterised in that the transfer device has a conversion device such that the motor (1) generates a plurality of revolutions of the rotor (3) during one percussion cycle.
10. Percussion mechanism as claimed in any one of claims 1 to 9, characterised in that the drive has two motors (1) which are operated to rotate in opposite directions and which jointly drive the drive element (7).
11. Percussion mechanism as claimed in any one of claims 1 to 10, characterised in that each of the motors (1) is allocated a transfer device (5, 6) for transferring the rotational movement generated by the respective motor into a longitudinal movement of the drive element (7).
12. Percussion mechanism as claimed in any one of claims 1 to 11, characterised in that

    - the percussion mechanism is a pneumatic-spring percussion mechanism;

    - the drive element is formed as a drive piston (7);

    - the percussion element is formed as percussion piston (9);

    - the coupling device has a drive pneumatic spring (10) which is formed in a hollow space between the drive piston and the percussion piston and by means of which the movement of the drive piston (7) can be transferred to the percussion piston (9).
13. Percussion mechanism as claimed in claim 12, characterised in that the coupling device has, in addition to the drive pneumatic spring, a recuperating pneumatic spring (12) operative between the drive piston (7) and the percussion piston (9) for assisting a rearward movement of the percussion piston (9) after one percussion action.
14. Percussion mechanism as claimed in any one of claims 1 to 13, characterised in that the motor (1) is formed as an asynchronous motor, a magnet motor or a different synchronous motor.
15. Percussion mechanism as claimed in any one of claims 1 to 14, characterised in that the motor (1) is formed as a wound, closed-loop linear motor.

Images