Oscillator unit for a hand-held tool

Abstract

Oscillator unit (10) for a hand-held tool and in particular for a surgical saw, comprising: - an eccentric (20) with a connecting part (31) and with an eccentric body (30) which is rotationally symmetrical about an eccentric axis (39); - a drive shaft (51) drivable by a drive and arranged along a drive axis (59); - an oscillator (60) with a pivot arm (61) rotatably arranged about an output shaft (69) and connected to a first contact arm (63) and a second contact arm (65); wherein the eccentric shaft (39) is spaced from the drive shaft (59), wherein the eccentric body (30) has a guide surface (33), wherein the first contact arm (63) has a first contact surface (64) and the second contact arm (65) has a second contact surface (66), wherein the first contact surface (64) and the second contact surface (66) are in contact with the guide surface (33), wherein the eccentric body (30) is connected to the drive shaft (51) via the connecting part (31) in a rotationally fixed manner, wherein the eccentric body (30) is rotatable by a rotary movement of the drive shaft (51) via the connecting part (31), wherein the first contact surface (64) and the second contact surface (66) are in frictional contact with the guide surface (33) such that a rotary movement (58) of the drive shaft (51) is transmitted via the connecting part (31), the eccentric body (30) and the guide surface (33) to the first contact surface (64) and to the second contact surface (66) and the first contact arm (63) and the second contact arm (65) are set in a back and forth movement and consequently the pivot arm (61) experiences an oscillating movement (68) about the output axis (69), characterized in that the eccentric body (30) has a cavity (34).

Description

Technical area

[0001] Oscillator unit for a hand-held tool, in particular for a surgical saw background

[0002] The invention relates to an oscillator unit for a hand-held tool and in particular for a surgical saw, comprising: - an eccentric with a connecting part and with an eccentric body that is rotationally symmetrical about an eccentric axis; - a drive shaft arranged along a drive axis and drivable by a drive; - an oscillator with a pivoting arm arranged to rotate about an output axis, which is connected to a first contact arm and a second contact arm.

[0003] The eccentric axis is spaced from the drive axis.

[0004] The eccentric body has a guide surface.

[0005] The first contact arm has a first contact surface and the second contact arm has a second contact surface.

[0006] The first contact surface and the second contact surface are in contact with the guide surface. The eccentric body is connected to the drive shaft via the connecting part in a rotationally fixed manner. The eccentric body can be rotated by a rotational movement of the drive shaft via the connecting part.

[0007] The first contact surface and the second contact surface are in frictional contact with the guide surface in such a way that a rotary movement of the drive shaft is transmitted via the connecting part, the eccentric body and the guide surface to the first contact surface and to the second contact surface and the first contact arm and the second contact arm are set in a back and forth movement and consequently the pivot arm experiences an oscillating movement about the output axis. State of the art

[0008] DE11 2021 004 591 T5 discloses an oscillating power tool in which an oscillating member or oscillating fork is coupled to the eccentric bearing to convert a rotary motion of the eccentric bearing into an oscillating motion. A drive shaft is connected to an eccentric shaft, which is connected to the eccentric bearing in such a way that a rotary motion of the drive shaft is converted into a wobbling motion of the eccentric bearing, causing the oscillating member to undergo a reciprocating or oscillating motion.

[0009] EP 1 428 625 A1 discloses an oscillating power tool whose eccentric cooperates with an eccentric fork to oscillate the output shaft. The eccentric is driven in rotation by an eccentric shaft arranged parallel to the output shaft.

[0010] From CN 206317026 U an oscillating power tool is known whose eccentric fork is arranged parallel or perpendicular to the output shaft.

[0011] Machinery's Handbook 1981, ISBN 0-8311-1129-1, pages 2055 to 2061, reports on static and dynamic imbalance and methods for correcting it. https: / / de.wikipedia.org / wiki / Achsmanschette (2025-05-28) provides information on axle boots, driveshaft boots, or cardan shaft boots, which are special rubber or plastic bellows. References are Haan-Gruiten 2002, ISBN 3-8085-2067-1, and Vogel, Würzburg 1991, ISBN 3-8023-0857-3. Short description

[0012] The invention relates to an oscillator unit for a hand-held tool and in particular for a surgical saw, comprising: - an eccentric with a connecting part and with an eccentric body that is rotationally symmetrical about an eccentric axis; - a drive shaft arranged along a drive axis and drivable by a drive; - an oscillator with a pivoting arm arranged to rotate about an output axis, which is connected to a first contact arm and a second contact arm.

[0013] The eccentric axis is spaced from the drive axis.

[0014] The eccentric body has a guide surface.

[0015] The first contact arm has a first contact surface and the second contact arm has a second contact surface.

[0016] The first contact surface and the second contact surface are in contact with the guide surface. The eccentric body is connected to the drive shaft via the connecting part in a rotationally fixed manner. The eccentric body can be rotated by a rotational movement of the drive shaft via the connecting part.

[0017] The first contact surface and the second contact surface are in frictional contact with the guide surface in such a way that a rotary movement of the drive shaft is transmitted via the connecting part, the eccentric body and the guide surface to the first contact surface and to the second contact surface and the first contact arm and the second contact arm are set in a back and forth movement and consequently the pivot arm experiences an oscillating movement about the output axis.

[0018] The eccentric body has a hollow space.

[0019] The advantage of the cavity is that the cavity contributes to weight reduction and at the same time provides space for balancing weight.

[0020] In one variant, the first contact arm may have a first contact element to which the first contact surface is assigned, and the second contact arm may have a second contact element to which the second contact surface is assigned.

[0021] The advantage is that the contact arm is directly coupled to the guide surface via a contact surface or a contact element with a spring effect is arranged between the contact arm and the contact surface.

[0022] In a further variant, the guide surface can be designed as an outer surface of the eccentric body and a second eccentric surface can be designed as an inner surface of the eccentric body.

[0023] The advantage is that balancing weights can be attached to the second eccentric surface, which is an inner surface of the eccentric body.

[0024] In a particular variant, the guide surface can be designed as an inner surface of the eccentric body and a second eccentric surface can be designed as an outer surface of the eccentric body.

[0025] The advantage is that balancing weights are attached to the second eccentric surface, which is an outer surface of the eccentric body.

[0026] In another special variant, the contact surface is connected to the guide surface under a predetermined tension.

[0027] The advantage is that the contact surfaces are always in contact with the guide surface.

[0028] In an advantageous variant, the wall thickness of the eccentric body can vary radially and / or axially.

[0029] The advantage is that a targeted weight distribution can be achieved around the circumference of the eccentric body to balance the eccentric body.

[0030] In a further variant, the second eccentric surface can be designed as an inner surface or as an outer surface of the eccentric body.

[0031] The advantage is that the balancing weights can be attached to the second eccentric surface, which is an inner surface or an outer surface of the eccentric body.

[0032] In a special variant, the cavity can be designed as one or more recesses in the eccentric body.

[0033] The advantage is that recesses can be created in the eccentric body to balance the eccentric body.

[0034] In one variant, the drive axis can be arranged perpendicular to the output axis.

[0035] In another variant, the drive axis can be arranged parallel to the output axis.

[0036] The advantage is that the positions of the drive and a tool mounted on the output shaft can be varied relative to each other as required.

[0037] In a further variant, the connecting part can partially or completely cover a first opening, i.e., one side of the eccentric body.

[0038] The advantage is that the connecting part is used only as a force transmission part, or also as a sealing part to seal one side of the eccentric body.

[0039] In a further variant, the first contact arm can be arranged so that it can be folded relative to the second contact arm about a folding axis, parallel to the eccentric axis, or the first contact arm can be arranged so that it can be pivoted relative to the swivel arm and to the second contact arm about a axis parallel to the output axis.

[0040] The advantage is that this makes it easier to mount the contact arms to the guide surface. Character list

[0041] The invention is explained in more detail below with reference to the drawings. These show: Fig. 1: a schematic perspective view of an oscillator unit with a guide surface as an inner surface, Fig. 2: a schematic perspective view of the oscillator unit of Fig. 1 but with a guide surface as an outer surface, Fig. 3: a schematic plan view of the oscillator unit of Fig. 1, Fig. 3a: a schematic, detailed cross-sectional view A of Fig. 3, Fig. 3b: another schematic, detailed cross-sectional view A of Fig. 3, Fig. 3c: another schematic, detailed cross-sectional view A of Fig. 3, Fig. 3d: another schematic, detailed cross-sectional view A of Fig. 3, Fig. 4: a schematic plan view of the oscillator unit of Fig. 2, Fig. 4a: a schematic, detailed cross-sectional view B of Fig. 4, Fig. 4b: another schematic, detailed cross-sectional view B of Fig. 4, Fig. 4c: another schematic, detailed cross-sectional view B of Fig. 4, Fig. 4d: another schematic, detailed cross-sectional view B of Fig. 4, Fig. 5: a schematic perspective view of an eccentric body of Fig. 1 with a varying wall thickness, Fig. 6: a schematic perspective view of the eccentric body of Fig. 1 with balancing weights on a second outward-facing eccentric surface of the eccentric body, Fig. 7: a schematic perspective view of the eccentric body of Fig. 2 with balancing weights on a second inward-facing eccentric surface of the eccentric body, Fig. 8: a schematic perspective view of the eccentric body with recesses, Fig. 9: a schematic perspective view of the oscillator unit of Fig. 1, but with a drive axis parallel to an output axis, Fig. 10: a schematic perspective view of the oscillator unit of Fig. 2, but with the drive axis parallel to the output axis, Fig. 11: a schematic perspective view of the eccentric body of Fig. 1, with a hollow body, a first opening and a second opening, Fig. 12a: a schematic perspective view of an oscillator of Fig. 1, with a first, foldable contact arm, Fig. 12b: a schematic perspective view of the oscillator of Fig. 2, with a first, pivotable contact arm. Detailed description

[0042] Fig. 1 shows a schematic perspective view of an oscillator unit 10 for a hand-held oscillating tool, in particular a hand-held surgical saw, comprising an eccentric 20 and an oscillator 60.

[0043] The eccentric 20 has an eccentric body 30 which is rotationally symmetrical about an eccentric axis 39.

[0044] The eccentric body 30 is essentially a cylinder with an outer surface that is the surface of the cylinder's outside, and an inner surface that is the surface of the cylinder's inside. The eccentric body 30 has a guide surface 33 that is arranged either on the cylinder's inside or on the cylinder's outside. The guide surface 33 can, as shown in Fig. 6, Fig. 7, Fig. 8, a smooth cylindrical surface. However, the guide surface 33 can also be, as shown in Fig. 3a to 3d and 4a to 4b, a curved surface, which differs from the smooth, cylindrical surface. Smooth means that the cylindrical surface is created by the rotation of a straight line. Curved means that the cylindrical surface is created by the rotation of a partially curved line.

[0045] The oscillator 60 is provided with a pivot arm 61 arranged to rotate about an output shaft 69 and connected to a first contact arm 63 and a second contact arm 65. The first contact arm 63 can have a first contact surface 64 arranged directly on the first contact arm 63. The second contact arm 65 can also have a second contact surface 66 arranged directly on the second contact arm 65.

[0046] As in the Fig. 12a and Fig. As shown in Figure 12b, the pivot arm 61 and the contact arms 63, 65 can be T-shaped. Other shapes, such as Y-shaped, are also suitable.

[0047] The first contact surface 64 and the second contact surface 66 are in frictional contact with the guide surface 33, so that the oscillator 60 is coupled to the eccentric 20.

[0048] The oscillator unit 10 further comprises a drive shaft 51 arranged along a drive axis 59, which can be driven by a drive.

[0049] The eccentric axis 39 is essentially parallel to the drive axis 59. However, there may also be an angle between the eccentric axis 39 and the drive axis 59. The eccentric axis 39 and the drive axis 59 are spaced apart to ensure eccentricity.

[0050] The eccentric 20 has a connecting part 31, with which the eccentric body is connected to the drive shaft 51 in a rotationally fixed manner.

[0051] The eccentric body 30 can be rotated by a rotational movement of the drive shaft 51 via the connecting part 31.

[0052] The first contact surface 64 and the second contact surface 66 are in frictional contact with the guide surface 33 in such a way that a rotary movement 58 of the drive shaft 51 is transmitted via the connecting part 31, the eccentric body 30 and the guide surface 33 to the first contact surface 64 and to the second contact surface 66 and the first contact arm 63 and the second contact arm 65 are set in a back and forth movement and consequently the pivot arm 61 experiences an oscillating movement 68 about the output axis 69.

[0053] That is, a wobbling movement of the eccentric body 30 is converted into an oscillating movement 68 of the swivel arm 61.

[0054] Fig. 11 shows that the eccentric body 30 has a cavity 34, which contributes to weight reduction and at the same time provides space for balancing weights 91, 92 for static and / or dynamic balancing.

[0055] If the guide surface 33 is an outer surface of the eccentric body 30, then a second eccentric surface 32 is, by definition, an inner surface of the eccentric body 30. Conversely, if the guide surface 33 is an inner surface of the eccentric body 30, then the second eccentric surface 32 is, by definition, an outer surface of the eccentric body 30.

[0056] Fig. 6 and Fig. 7 show that the balancing weights 91, 92 can be attached to the second eccentric surface 32. Fig. 6 shows the balancing weights 91, 92 on the outside of the eccentric body 30. Fig. 7 shows the balancing weights 91, 92 on the inside of the eccentric body 30.

[0057] According to one embodiment of the invention, the first contact arm 63 can directly contact a first contact surface 64 (see Fig. 3c and Fig. 3d) and the second contact arm 65 directly have a second contact surface 66. In Fig. 4a to 4d, each contact element can be connected by the contact arm 63 of Fig. 3c and Fig. 3d, which is in direct contact with the first contact surface 64. The second contact arm 65 and the second contact surface 66 were Fig. 4a to 4d are not shown, but these are symmetrical images of the first contact arm 63 and the first contact surface 64.

[0058] According to a further embodiment of the invention, the first contact arm 63 can have a first contact element 43 to which the first contact surface 64 is assigned and the second contact arm 65 can have a second contact element 45 to which the second contact surface 46 is assigned. Fig. 3 shows a schematic plan view of the oscillator unit 10 of Fig. 1, with the guide surface 33 as an inner surface of the eccentric body 30. The detail A related to the first contact arm 63 is shown in Fig. 3a to 3d and 4a to 4b, which also applies to the second contact arm 65. The first contact arm 63 and the second contact arm 65 are symmetrical to each other.

[0059] The guide surface 33 can, as in Fig. 3a to 3d and 4a to 4b, may be a curved surface that differs from the smooth, cylindrical surface.

[0060] Fig. Figure 3a shows a schematic, detailed cross-sectional view A of Fig. 3. The guide surface 33 of Fig. 3a, however, is not entirely cylindrical, but partially curved. The first contact element 43 is firmly connected to the first contact arm 63. The first contact element 43 is an elastic, one-piece, spring-loaded element, which, with its first contact surface 64, is in contact with the guide surface 33 under a predetermined tension. The pretension and the curved shape of the first contact surface 64, as well as the curved shape of the guide surface 33, ensure constant contact between the guide surface 33 and the first contact surface 64. This constant contact prevents the contact arm from striking the guide surface.

[0061] Fig. Figure 3b shows another schematic, detailed cross-sectional view A of Fig. 3. The difference between the first contact element 43 in Fig. 3a and Fig. 3b is that the first contact element 43 is a resilient pressure piece. The first contact surface 64 is a ball or a pin.

[0062] Fig. Figure 3c shows another schematic, detailed cross-sectional view A of Fig. 3. The difference between the embodiment in the Fig. 3a and Fig. 3c is that the first contact surface 64 in Fig. 3c is arranged directly on the first contact arm 63.

[0063] Fig. Figure 3d shows another schematic, detailed cross-sectional view A of Fig. 3. The difference between the embodiment in the Fig. 3d and Fig. 3c is that the guide surface 33 in Fig. 3c is only partially curved, but the guide surface 33 in Fig. 3d has a U-shaped cross-section and thus a U-shaped surface.

[0064] The advantage of curved or even U-shaped cross sections of the guide surface 33 is the stable contact between the contact surface 64 and guide surface 33. For the embodiments according to Fig. 3a to Fig. 3d, for the purpose of assembling the oscillator 60 with the eccentric 20, the contact arms 63, 65 of the oscillator 60 can be tilted so that they can be pushed through the second opening 36 of the eccentric body 30. The contact arms 63, 65 can then be raised to properly contact the guide surface 33.

[0065] The advantage of smooth and cylindrical cross-sections of the guide surface 33 is the simple coupling of the contact arms 63, 65 with the guide surface 33. In this case, the contact arms 63, 65 of the oscillator 60 can be pushed through the second opening 36 of the eccentric body 30 onto the guide surface 33 (see also Fig. 11).

[0066] Fig. 4 shows a schematic plan view of the oscillator unit 10 of Fig. 2. The guide surface 33 is an outer surface of the eccentric body 30.

[0067] Fig. Figure 4a shows a schematic, detailed cross-sectional view B of Fig. 4. The first contact element 43 is a spring-loaded pressure piece. The first contact surface 64 is a ball or a pin. The cross-section of the guide surface 33 is partially curved.

[0068] Fig. Figure 4b shows another schematic, detailed cross-sectional view B of Fig. 4. The difference between the first contact element 43 in Fig. 4a and Fig. 4b is that the first contact element 43 in Fig. 4b an elastic, one-piece, resilient element which is in contact with the guide surface 33 with its first contact surface 64.

[0069] Fig. Figure 4c shows another schematic, detailed cross-sectional view B of Fig. 4. The difference between the guide surface 33 in Fig. 4a and Fig. 4c is that the guide surface 33 in Fig. 4a is only partially curved, but the guide surface 33 in Fig. 4c has a U-shaped cross-section.

[0070] Fig. Figure 4d shows another schematic, detailed cross-sectional view B of Fig. 4. The difference between the guide surface 33 in Fig. 4b and Fig. 4d is that the guide surface 33 in Fig. 4b is only partially curved, but the guide surface 33 in Fig. 4d has a U-shaped cross-section.

[0071] In a special embodiment, the eccentric body 30 can be statically and dynamically balanced. Static and dynamic balancing has long been known in the art.

[0072] Fig. 5 shows a schematic perspective view of the eccentric body 30 of Fig. 1 with a varying wall thickness 95, 96, which can be varied radially and / or axially. The variation can occur continuously or incrementally. The variation in wall thickness can lead to a weight shift on the circumference of the eccentric body 30. This can be utilized for static and dynamic balancing.

[0073] Fig. 6 shows a schematic perspective view of the eccentric body 30. Balancing weights 91, 92 are attached to the second eccentric surface 32, which here is the outer surface of the eccentric body 30, for static and dynamic balancing of the eccentric body 30.

[0074] Fig. 7 shows a schematic perspective view of the eccentric body 30. Balancing weights 91, 92 are attached to the second eccentric surface 32, which here is the inner surface of the eccentric body 30, for static and dynamic balancing of the eccentric body 30.

[0075] The balancing weights 91, 92 are shown here as examples. One balancing weight or a plurality of balancing weights can be attached to different locations on the inner surface, outer surface, or at any desired location on the eccentric body 30.

[0076] Fig. Figure 8 shows a schematic perspective view of the eccentric body 30. The cavity 34 is formed here as a recess 81, 82, 83 in the eccentric body 30. The recesses can have any shape and be continuous, or they can be formed as blind holes and placed at any location. If appropriate, the recesses can be filled with other materials having different specific densities.

[0077] The Fig. 6, Fig. 7 and Fig. The embodiments shown in Figure 8 can be used for static and dynamic balancing.

[0078] Fig. Figure 9 shows a schematic perspective view of the oscillator unit of Fig. 1, but with the drive axis parallel to the output axis.

[0079] The embodiment of Fig. 9 is particularly suitable for installing the oscillator unit in a housing and handle of a hand-held tool. This means that the eccentric body 30 can be installed in the handle of the hand-held tool, and the oscillator 60 can be installed in the housing of the hand-held tool.

[0080] In contrast, the design of the Fig. 1 suitable for the installation of the oscillator unit 10 in the housing of the hand-held tool.

[0081] Fig. 10 shows a schematic perspective view of the oscillator unit of Fig. 2, but with a drive axis parallel to an output axis.

[0082] The embodiment of Fig. 10 is particularly suitable for installing the oscillator unit 10 in a housing and handle of a hand-held tool. This means that the eccentric body 30 can be installed in the handle of the hand-held tool, and the oscillator 60 can be installed in the housing of the hand-held tool.

[0083] In contrast, the embodiment of Fig. 2 suitable for the installation of the oscillator unit in the housing of the hand-held tool.

[0084] Fig. Figure 12a shows a schematic perspective view of an oscillator 60 of Fig. 1, with a first, foldable contact arm 63. The assembly and coupling of the oscillator to the guide surface 33 has already been reported. The foldable contact arm 63 facilitates the insertion and coupling of the oscillator 60 to the guide surface 33, in the sense that the oscillator 60 is inserted into the eccentric body 30 with the folded contact arm 63, and then the contact arm 63 is folded back.

[0085] Fig. Figure 12b shows a schematic perspective view of the oscillator 60 of Fig. 2, with a first, pivotable contact arm 63. The pivotable contact arm 63 facilitates the insertion and coupling of the oscillator 60 with the guide surface 33, in the sense that the oscillator 60 with the pivoted contact arm 63 is inserted into the eccentric body 30 and then the contact arm 63 is pivoted back.

[0086] According to a further embodiment, the friction and wear between the contact surfaces 64, 66 and the guide surface 33 is reduced.

[0087] To reduce wear, the contact surfaces 64, 66, and the guide surface 33 must be lubricated. Sleeves are known from the prior art. Common designs include axle sleeves, drive shaft sleeves, cardan shaft sleeves, or bellows made of rubber or plastic. A lubricant-filled sleeve according to the prior art can be placed over the eccentric body 30, which is sealingly connected to the drive shaft 51 and the pivot arm 61. It is essential that the sleeve is not in contact with the rotating eccentric body 30.

[0088] The eccentric 20 has a connecting part 31, with which the eccentric body is connected in a rotationally fixed manner to the drive shaft 51. The connecting part 31 at least partially covers a first opening 35 of the eccentric body 30 (see Fig. 11). The connecting part 31 can also seal the entire first opening 35 of the eccentric body 30. In such a case, the sleeve can be sealingly connected to the rotating eccentric body 30 on one side. The other side of the sleeve must be connected to a rotating seal (not shown here) associated with the pivot arm 61 according to the prior art.

[0089] To reduce friction and wear between the contact surfaces 64, 66 and the guide surface 33, various materials can be considered for the contact element or the contact surface, as well as for the eccentric body 30 or the guide surface 33. For this purpose, metal can be paired with metal, metal with plastic, or plastic with plastic. It is also possible to select ceramic instead of metal or plastic.

[0090] The material pairing must enable the desired friction reduction, which can reduce the frictional force. Table 1 provides some example friction values ​​for various material pairings. Table 1 Metallwerkstoffe Schmierung Reibungswert Stahl - Stahl trocken 0,15 Stahl - Stahl geschmiert 0,10 Stahl - Polyamid trocken 0,30 Stahl - PTFE trocken 0,04 Stahl - PTFE geschmiert 0,04

[0091] Lower friction values ​​for the material pairings can also achieve lower frictional resistance. Higher friction values ​​also generally lead to greater wear between the components of the eccentric. Commercially available spring-loaded thrust pieces can be used to reduce or even prevent wear.

[0092] A spring plunger is a machine component and consists of a threaded sleeve with an internal spring that presses on a ball.

[0093] The spring force is designed to ensure sufficient preload between the contact surface and the guide surface. The ball can be made of plastic, steel, or ceramic.

[0094] More generally, the spring pressure piece can have any other type of rolling element instead of a ball, e.g. rollers, barrels, needles or cones.

[0095] In order to keep wear to a minimum, the eccentric body 30 or the guide surface 33 can be made of steel and the contact element 43, 45 can have a resilient pressure piece with a rolling element, e.g. a ball made of plastic, steel or ceramic.

[0096] A sensible combination of different designs is possible. For example, the contact elements can be freely selected for different designs. The designs of the Fig. 5, Fig. 6, Fig. 7 and Fig. 8 can be combined to achieve a suitable balancing of the eccentric body. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2021 004 591 T5

[0008] EP 1 428 625 A1

[0009] CN 206317026 U

[0010] Cited non-patent literature

[0000] Machinery's Handbook 1981, ISBN 0-8311-1129-1

[0011] Haan-Gruiten 2002, ISBN 3-8085-2067-1

[0011] Vogel, Würzburg 1991, ISBN 3-8023-0857-3

[0011]

Claims

[1] Oscillator unit (10) for a hand-held tool and in particular for a surgical saw, comprising: - an eccentric (20) with a connecting part (31) and with an eccentric body (30) which is rotationally symmetrical about an eccentric axis (39); - a drive shaft (51) drivable by a drive and arranged along a drive axis (59); - an oscillator (60) with a pivot arm (61) rotatably arranged about an output shaft (69) and connected to a first contact arm (63) and a second contact arm (65); wherein the eccentric shaft (39) is spaced from the drive shaft (59), wherein the eccentric body (30) has a guide surface (33), wherein the first contact arm (63) has a first contact surface (64) and the second contact arm (65) has a second contact surface (66), wherein the first contact surface (64) and the second contact surface (66) are in contact with the guide surface (33), wherein the eccentric body (30) is connected to the drive shaft (51) via the connecting part (31) in a rotationally fixed manner, wherein the eccentric body (30) is rotatable by a rotary movement of the drive shaft (51) via the connecting part (31), wherein the first contact surface (64) and the second contact surface (66) are in frictional contact with the guide surface (33) such that a rotary movement (58) of the drive shaft (51) is transmitted via the connecting part (31), the eccentric body (30) and the guide surface (33) to the first contact surface (64) and to the second contact surface (66) and the first contact arm (63) and the second contact arm (65) are set in a back and forth movement and consequently the pivot arm (61) experiences an oscillating movement (68) about the output axis (69), characterized by , that the eccentric body (30) has a cavity (34). [2] Oscillator unit (10) according to claim 1, wherein the first contact arm (63) has a first contact element (43) to which the first contact surface (64) is assigned and the second contact arm (65) has a second contact element (45) to which the second contact surface (46) is assigned. [3] Oscillator unit (10) according to claim 1 or 2, wherein the guide surface (33) is formed as an outer surface of the eccentric body (30), and a second eccentric surface (32) is formed as an inner surface of the eccentric body (30). [4] Oscillator unit (10) according to claim 1 or 2, wherein the guide surface (33) is formed as an inner surface of the eccentric body (30), and a second eccentric surface (32) is formed as an outer surface of the eccentric body (30). [5] Oscillator unit (10) according to one of claims 3 or 4, wherein the first contact surface (64) and the second contact surface (66) are connected to the guide surface (33) under a predetermined tension. [6] Oscillator unit (10) according to one of claims 2 to 5, wherein a wall thickness (95, 96) of the eccentric body (30) is radially and / or axially variable. [7] Oscillator unit (10) according to one of the preceding claims, wherein balancing weights (91, 92) for static and dynamic balancing of the eccentric body (30) can be applied to the second eccentric surface (32) of the eccentric body (30). [8] Oscillator unit (10) according to claim 3, wherein the cavity (34) is formed as a recess (81, 82, 83) in the eccentric body (30). [9] Oscillator unit (10) according to one of claims 1 to 8, wherein the eccentric (20) is arranged relative to the oscillator (60) such that the drive axis (59) is perpendicular to the output axis (69). [10] Oscillator unit (10) according to one of claims 1 to 8, wherein the eccentric (20) is arranged relative to the oscillator (60) such that the drive axis (59) is parallel to the output axis (69). [11] Oscillator unit (10) according to one of the preceding claims, wherein the connecting part (31) at least partially covers a first opening (35) of the eccentric body (30). [12] Oscillator unit (10) according to one of the preceding claims, wherein the first contact arm (63) is arranged to be foldable relative to the second contact arm (65) about a folding axis (49) parallel to the eccentric axis (39) or to be pivotable relative to the pivot arm (61) and the second contact arm (65) about a pivot axis (79) parallel to the output axis (69).

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