Oscillation drive with adjustable oscillation angle

Abstract

An oscillation drive with a drive and with an eccentric coupling drive for converting a rotary motion of the drive into an oscillating rotary motion of a tool spindle about its longitudinal axis is disclosed, wherein the eccentric coupling drive has an eccentric with a first eccentricity that is driven by the drive and that works together with a coupling element that is coupled to the tool spindle in order to convert the motion of the eccentric into an oscillating rotary motion of the tool spindle, wherein the eccentric is coupled to an additional eccentric with a second eccentricity so that the eccentricities are superimposed, wherein the relative position between the eccentric and the additional eccentric is adjustable to at least two different positions in order to change the amplitude of the oscillating motions of the tool spindle.

Claims

1. An oscillation drive comprising: a drive; and an eccentric coupling drive for converting a rotary motion of the drive into an oscillating rotary motion of a tool spindle about a longitudinal axis, wherein the eccentric coupling drive has a first eccentric with a first eccentricity that is driven by the drive and that works together with a coupling element that is coupled to the tool spindle to convert a motion of the eccentric into an oscillating rotary motion of the tool spindle, and wherein the first eccentric is coupled to an additional eccentric with a second eccentricity so that eccentricities are superimposed, wherein a relative position between the first eccentric and the additional eccentric is adjustable to at least two different positions in order to change an amplitude of the oscillating motion of the tool spindle.

2. The oscillation drive according to claim 1, wherein the drive is reversible in its direction of rotation in order to cause a switchover between a first relative position of the first eccentric and the additional eccentric in which the two eccentricities are superimposed additively, and a second relative position in which the eccentricities of the first eccentric and the additional eccentric are superimposed subtractively.

3. The oscillation drive according to claim 2, wherein the first eccentric and the additional eccentric are rotatable by 180° relative to one another between the first and second relative positions.

4. The oscillation drive according to claim 1, wherein the coupling element is an oscillating fork, which is rigidly attached at a first end to the tool spindle and is driven at a second end by the additional eccentric.

5. The oscillation drive according to claim 4, wherein the additional eccentric is rotatably mounted on the first eccentric, and wherein the second end of the oscillating fork encloses, an eccentric bearing that is held on the additional eccentric.

6. The oscillation drive according to claim 4, wherein the eccentric bearing is a spindle bearing with a crowned outer ring that is enclosed by two fork ends of the oscillating fork.

7. The oscillation drive according to claim 1, wherein the first eccentric has an eccentric stub that engages an eccentrically located recess of the additional eccentric, the eccentric bearing being held on an outer surface of the additional eccentric.

8. The oscillation drive according to claim 7, wherein the eccentric stub is implemented at one end of an output shaft of the drive that is driven in rotation.

9. The oscillation drive according to claim 8, wherein the drive has an electric motor with a motor shaft connected to the eccentric stub.

10. The oscillation drive according to claim 9, wherein a sleeve, which is adapted to be coupled to the additional eccentric in at least two relative positions by means of a driver, is arranged on the motor shaft in a rotationally fixed manner.

11. The oscillation drive according to claim 10, wherein the additional eccentric has a disk that is rotatably arranged inside the sleeve and strikes against a lug of the sleeve in the at least two relative positions.

12. The oscillation drive according to claim 11, wherein the disk has an elastic section that expands outward under the action of centrifugal force and rests against an inside surface of the sleeve to fix the relative position between the first eccentric and the additional eccentric.

13. The oscillation drive according to claim 10, wherein a brake system is provided that permits braking of the motor shaft in the stationary condition relative to a housing and that releases under the action of centrifugal force when the motor shaft is rotating in order to end the braking action.

14. The oscillation drive according to claim 13, wherein the sleeve has a slide guide in the form of a recess, through which a driver pin in an associated driver receptacle on the additional eccentric engages, in order to define the relative position between the first eccentric and the additional eccentric.

15. The oscillation drive according to claim 14, wherein the brake system has two spring-loaded, radially movable brake shoes for braking on the housing of the additional eccentric during a reversal of direction of rotation, which shoes expand outward under the action of centrifugal force against the spring action in order to stop the braking.

16. The oscillation drive according to claim 15, wherein a bearing sleeve, which the brake shoes contact during a reversal of direction of rotation, is held on the housing, and wherein the brake shoes rest against an inside surface of the sleeve under the action of centrifugal force in order to thus fix the relative position between the first eccentric and the additional eccentric.

17. The oscillation drive according to claim 15, wherein the brake shoes are coupled to the additional eccentric by the driver pin, which extends through the slide guide of the sleeve into the driver receptacle.

18. A system comprising: an oscillation drive according to claim 1; a plurality of tools, wherein the tools have a coding; and a control unit adapted to automatically set an oscillation angle.

19. The system according to claim 18, wherein the control unit automatically sets the oscillation angle and/or the speed.

20. The system according to claim 18, wherein the coding is an RFID chip.

21. The system according to claim 18, wherein the drive has an electronically commutated electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 is a perspective representation of an oscillation drive according to an exemplary embodiment of the invention;

(3) FIG. 2 is a longitudinal section through the oscillation drive from FIG. 1;

(4) FIG. 3 is an exploded view of the essential parts of the drive train, which are shown with one another in the direction of installation along a longitudinal axis;

(5) FIG. 4 is a longitudinal section through the motor shaft and associated parts in the region of the support with the eccentric and additional eccentric in a first relative position between the eccentric and the additional eccentric, in which the two eccentricities are superimposed additively;

(6) FIG. 5 is a representation as in FIG. 4, but wherein the eccentric and the additional eccentric have been moved into a position rotated by 180° relative to one another, in which the two eccentricities are superimposed subtractively;

(7) FIG. 6 is an enlarged perspective representation of the motor shaft in the region of the brake system, wherein a number of parts have been cut out for the purposes of improved clarity;

(8) FIG. 7 is a representation as in FIG. 6, but wherein a longitudinal section passing through the central axis of the motor shaft has been provided;

(9) FIG. 8 is a modified implementation of the oscillation drive as in FIGS. 4 and 5 with a longitudinal section through the front part of the motor shaft, with associated support, eccentric, additional eccentric, and eccentric bearing in a first relative position between the eccentric and the additional eccentric, in which an additive superimposition of the two eccentricities is produced;

(10) FIG. 9 is a representation as in FIG. 8, but wherein the eccentric and the additional eccentric have been rotated by 180° relative to one another so that a subtractive superimposition of the two eccentricities is produced;

(11) FIG. 10 is an enlarged perspective representation of the embodiment from FIGS. 8 and 9, wherein the motor shaft along with the rotor body located thereon, the sleeve between the eccentric and the additional eccentric, and the eccentric bearing are visible;

(12) FIG. 11 is a front view of the arrangement from FIG. 10 after removal of the eccentric bearing, and

(13) FIG. 12 is a system with an oscillation drive as in FIG. 1 and with two associated tools.

DETAILED DESCRIPTION

(14) In FIG. 1, an oscillation drive according to the invention is shown in a perspective view and is labeled overall with reference number 10. The oscillation drive 10 has a housing 12 that can be grasped by one hand, and on the back end of which is provided a receptacle 14 for a rechargeable battery. A tool spindle 20 projects downward at right angles from a front end of the housing 12. Various tools can be attached to the tool spindle 20 by means of a quick-action chuck, for which purpose a locking lever 18 is provided, which is visible on the top of the housing 12. Also visible on the top of the housing 12 is an on/off switch 16, which serves to switch the machine on and off. In addition, a switch is provided for reversing the direction of rotation; it is arranged on the right-hand side of the housing 12.

(15) FIG. 2 shows a longitudinal section through the oscillation drive 10 from FIG. 1.

(16) The oscillation drive 10 has a drive 26, which in the present case is designed as an electronically commutated electric motor (EC motor). This has a motor shaft 27, which is rotatably mounted by means of two bearings 30, 32. The rotary motion of the motor shaft 27 is converted into an oscillating rotary motion of the tool spindle 20 about its longitudinal axis 21 by means of an eccentric coupling drive, as is indicated by the double-headed arrow 22. Whereas in conventional eccentric coupling drives, an eccentric motion of an eccentric provided on the end of the motor shaft by means of a crowned eccentric bearing and a rocker arm that acts on the eccentric bearing and is rigidly coupled to the tool spindle, has another eccentric is additionally provided, the so-called additional eccentric, by which means it becomes possible to vary the amplitude of the oscillating motion.

(17) Thus, in addition to an eccentric 34 with an eccentric stub 35 on the end of the motor shaft 27, an additional eccentric 36 is provided that is held directly on the eccentric stub 35 by a recess 37. The recess 37 is arranged eccentrically so that an eccentric motion is produced at the outer surface of the additional eccentric 36, which results from the superimposition of the two eccentricities of the eccentric 34 and the additional eccentric 36. Held on the outer surface of the additional eccentric 36 is an eccentric bearing 38 with a crowned outer ring, which is gripped on both sides by an oscillating fork 40 whose other end is rigidly connected to the tool spindle 20. The eccentric motion of the eccentric bearing 38 is consequently converted into an oscillating motion of the tool spindle 20.

(18) The eccentricity with which the eccentric bearing 38, and hence the rocker arm 40, is moved depends on the relative position between the eccentric 34 and the additional eccentric 36. In the position shown in FIG. 2, the eccentricities of the eccentric 34 and the additional eccentric 36 are additive, resulting in a maximum amplitude of the oscillating motion. In contrast, if the additional eccentric 34 were rotated by 180° relative to the position in FIG. 2, then a subtractive superimposition of the two eccentricities would result, producing a minimum deflection due to the eccentric motion, and thus a minimum amplitude of the oscillating motion.

(19) According to the invention, the switchover between these two relative positions that are rotated by 180° with respect to one another is accomplished by a reversal of the direction of rotation of the drive 26. The additional eccentric 36 remains stationary at startup until it is carried along by an associated stop of the eccentric 34. If the direction of rotation is reversed, then once again the additional eccentric 36 initially remains stationary before it is carried along in a position rotated by 180° by a stop of the eccentric 34.

(20) The stopping of the additional eccentric 36 can take place simply by inertia, or else can be forced by a brake system.

(21) The two variant embodiments are explained in detail below.

(22) FIGS. 2 to 7 show the embodiment with a brake system, while FIGS. 8 to 11 show an embodiment without such a brake system, in which the stopping of the additional eccentric during a reversal of direction of rotation takes place through inertia alone.

(23) In FIG. 3, the essential moving parts of the embodiment with a brake system are shown in an exploded view, one behind the other in the installation position. Shown on the left-hand end is the rocker arm 40, which encloses the eccentric bearing 38 at its crowned outer ring 39 with two fork ends 42, 43. The rocker arm 40 is fixed in a rotationally fixed manner on the tool spindle 20 by means of a recess 41, for example by shrink fitting.

(24) The eccentric stub 35 is formed on the motor shaft 27 at the outer end. The additional eccentric 36 is designed in the form of a sleeve, and has an eccentric recess 37 by which the additional eccentric 36 is held rotatably on the eccentric pin 35. Formed on the motor side of the additional eccentric 36 is a disk 44, in which a driver receptacle 46 is provided in the form of a radial groove 46.

(25) Adjoining the disk 44 of the additional eccentric 37 is a sleeve 48, in which a slide guide 50 is provided in the form of a groove that extends over an angular range of 180°. Provided on the rear side of the sleeve 50 is a brake system 54 that is labeled overall as 54 and that has two brake shoes 55, 56 that can move radially with respect to one another and that are spring-loaded inward by means of a spring ring 58 surrounding the outside. One of the brake shoes 56, 57, namely the bottom brake shoe 57 in the illustration in FIG. 3, is rotationally coupled to the additional eccentric 36 by a driver pin 52, which extends through the slide guide 50, since the driver pin 52 engages the driver receptacle 46 of the disk 44.

(26) The bearing 30 facing the tool spindle 20, which sits with its inner ring on the motor shaft 27, engages with its outer ring in a bearing sleeve 60 that is fixed in the housing 12. The bearing sleeve 60 has a projection 61 extending toward the tool spindle 20, on which the inner surfaces of the brake shoes 55, 56 can rest when they are pressed on by the spring ring 58.

(27) Also visible in FIG. 3 is an associated counterweight 62, which is provided on the outer end of the motor spindle 27 (see also FIG. 2).

(28) In FIG. 4, the two eccentricities, which are produced by the eccentric 34 or the eccentric pin 35 and the additional eccentric 36, are indicated by e1 and e2. While the eccentric pin 35 has a relatively large eccentricity e1, the eccentricity e2 caused by the additional eccentric 36 is smaller than the first eccentricity e1.

(29) In the position shown in FIG. 4, the relative position of the eccentric stub 35 and the additional eccentric 36 is such that the two eccentricities e1 and e2 are superimposed additively, so that the resulting total eccentricity is eg=e1+e2. If the eccentric and the additional eccentric are rotated by 180° with respect to one another as compared to the position from FIG. 4, then the position shown in FIG. 5 is produced, in which the two eccentricities e1 and e2 are superimposed subtractively, so that the resulting total eccentricity is eg=e1−e2.

(30) Depending on the size of the eccentricities e1 and e2, different resulting eccentricities are produced, so that the amplitude of the oscillation angle can be adjusted within relatively wide limits. For example, a combination of 2.6°/5.0° (amplitude of the oscillation angle from dead center to dead center) can be used.

(31) As is evident in detail from FIGS. 6 and 7, the two brake shoes 55, 56 are held on the projection 61 of the bearing sleeve 60 by the surrounding spring ring 58 when at a standstill or during a reversal of direction of rotation. Thus, during the reversal of direction of rotation, the additional eccentric 36 is rotationally held in place or braked by the driver pin 52, which engages the driver receptacle 46. The sleeve 48 sits on the outer surface of the motor shaft 27 in a rotationally fixed manner. If the motor shaft 27 now moves in the opposite direction of rotation during a reversal of direction of rotation, then the eccentric stub 35, which is rigidly connected to the motor shaft 27, moves relative to the additional eccentric 36 until the driver pin 52 strikes the other end of the slide guide 50, and the additional eccentric 36 is now carried along. With increasing speed the brake shoes 55, 56 move outward until they come to rest against an inside surface of the sleeve 48, so that the braking is released on the one hand and the relative position between the eccentric 34 and the additional eccentric 36 is fixed on the other hand.

(32) During a reversal of direction of rotation, the motor shaft 27 is first stopped, so that the additional eccentric 36 is again braked by means of the brake system 24 until finally the driver pin 52 comes to rest against the opposite end of the slide guide 50 and again carries the additional eccentric 36 along.

(33) FIGS. 8 to 11 show a simplified embodiment of the oscillation drive with no brake system, which is labeled overall as 10a. Correspondingly modified parts are labeled with corresponding reference symbols that are followed by the letter “a” while the other corresponding parts are labeled with corresponding reference symbols (in FIGS. 10 and 11, the rotor body 66 of the motor is also visible in addition).

(34) The sleeve-shaped additional eccentric 36a has a disk 44a (see, in particular, FIG. 8, 9, 11), one half of which is designed as an elastic section 70. The disk 44a is movable within the enclosing sleeve 48a, and has two ends 71, 72 on the elastic section 70 that can come to rest against one side or the other side of a projecting lug 68 of the sleeve 48a depending on the direction of rotation. Thus, depending on whether the additional eccentric 36a, and thus the disk 44a, is rotated clockwise or counterclockwise, one end 71 or the other end 72 of the elastic section 70 comes to rest against the lug 68, and is carried along as a result. With increasing speed, the elastic section 70 expands outward and comes to rest against the associated inner surface of the sleeve 48a so that the relative position between the eccentric 34 and the additional eccentric 36a, and thus the amplitude of the oscillating motion, is fixed.

(35) As already mentioned at the outset, different amplitudes of the oscillating motion are especially advantageous for different tools. The idea thus suggests itself of providing the applicable tools with suitable coding that can be read out automatically in order to accomplish automatic switchover of the amplitude of the oscillation angle.

(36) By way of example, FIG. 12 shows a system 100 with an oscillation drive 10 of the above-described type and with two tools 104 and 110 shown by way of example.

(37) The tool 104 is an elongated sawing tool with a cutting edge 109 on the outer edge. Provided for attachment is a mounting opening 108, with which interlocking mounting on the tool spindle 20 is made possible.

(38) To ensure automatic detection of the tool 104, an RFID chip is provided that is indicated schematically with 106.

(39) The oscillation drive 10 has control electronics that are merely indicated schematically with 102, and which automatically read out the RFID chip 106 and then automatically set an associated amplitude of the oscillation angle for it. The EC motor of the oscillation drive 10 is automatically operated by the control unit 102 with the associated direction of rotation that produces the desired oscillation angle.

(40) The second tool 110 shown by way of example is an abrasive tool with a relatively large backing pad that again is equipped with an RFID chip 106. Due to the relatively large inertia of the abrasive tool, this tool should normally be operated with a smaller amplitude of the oscillation angle. This setting to the smaller amplitude is again accomplished automatically by the control unit 102.

(41) In addition to an automatic setting of the amplitude of the oscillation angle, different speeds can also be stored so that the applicable tools can be used with an optimal combination of oscillation angle and speed.

(42) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.