Eccentric transmission for a power tool

Abstract

Power tool, in particular a pipe press, including a drive, an output shaft, a threaded spindle drive and a linear actuator, wherein a torque generated by the drive is transmissible via the output shaft, and the threaded spindle drive connected to the output shaft, to the linear actuator. The power tool includes an eccentric transmission device for a torque adaptation between the drive and the threaded spindle drive, wherein the eccentric transmission device includes a drive eccentric, which is drivable by the drive, an eccentric gear, which is drivable by the drive eccentric, and a compensating coupling, which is drivable by the eccentric gear and which serves for transmitting torque from the eccentric gear to the output shaft.

Claims

1-11. (canceled)

12: A power tool comprising: a drive; an output shaft; a threaded spindle drive connected to the output shaft; a linear actuator, a torque generated by the drive being transmissible via the output shaft and the threaded spindle drive to the linear actuator; and an eccentric transmission for a torque adaptation between the drive and the threaded spindle drive, the eccentric transmission including a drive eccentric drivable by the drive, an eccentric gear drivable by the drive eccentric, and a compensating coupling drivable by the eccentric gear and serving for transmitting torque from the eccentric gear to the output shaft.

13: The power tool as recited in claim 12 further comprising a ring gear fixedly connected to a housing, the ring gear and the eccentric gear having teeth defining an involute toothing between the ring gear and the eccentric gear.

14: The power tool as recited in claim 12 wherein the compensating coupling is configured as a parallel crank coupling.

15: The power tool as recited in claim 12 wherein the eccentric transmission is configured in one stage and with a transmission ratio of 1:10 to 1:100.

16: The power tool as recited in claim 13 wherein the eccentric gear and the ring gear have a tooth number difference of 1 to 2 teeth.

17: The power tool as recited in claim 13 wherein the ring gear has between 20 and 200 teeth.

18: The power tool as recited in claim 13 wherein the ring gear has a maximum inside diameter of between 20 and 200 mm.

19: The power tool as recited in claim 13 wherein the ring gear is rotatably mounted in the housing.

20: The power tool as recited in claim 13 wherein the eccentric transmission at least partially consists of a metallic sintered material.

21: The power tool as recited in claim 13 wherein the eccentric transmission device at least partially consists of a polymer.

22: The power tool as recited in claim 12 wherein the eccentric gear contains at least one aperture for receiving a coupling element of the compensating coupling, a diameter of the aperture corresponding at least to a diameter of a coupling element and to twice a value of an eccentricity of the eccentric gear.

23: A pipe press comprising the power tool as recited in claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The figures, the description and the patent claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to produce useful further combinations.

[0028] In the figures, identical and similar components and assemblies are denoted by the same reference signs.

[0029] Specifically:

[0030] FIG. 1 shows a side view of a power tool in the form of a pipe press;

[0031] FIG. 2 shows a sectional side view of the power tool in the exemplary form of a pipe press, with a drive, an output shaft, a threaded spindle drive, a linear actuator and an eccentric transmission device;

[0032] FIG. 3 shows a perspective sectional view of the power tool in the exemplary form of a pipe press, with the drive, the output shaft, the threaded spindle drive, the linear actuator and the eccentric transmission device;

[0033] FIG. 4 shows a perspective sectional view of the eccentric transmission device with a part of the output shaft and a first and second bearing;

[0034] FIG. 5 shows a front view of the eccentric transmission device with a drive eccentric, an eccentric gear and a ring gear;

[0035] FIG. 6 shows a perspective sectional view of the drive, the output shaft, the first bearing, the drive eccentric and an eccentric gear;

[0036] FIG. 7 shows a sectional side view of the drive, the output shaft, the first bearing, the drive eccentric and the eccentric gear;

[0037] FIG. 8 shows a perspective view of the drive eccentric with a compensating weight;

[0038] FIG. 9 shows a side view of the drive eccentric with the compensating weight; and

[0039] FIG. 10 shows a sectional side view through the drive eccentric.

DETAILED DESCRIPTION

[0040] FIGS. 1 to 3 show a power tool 1 according to the invention in an exemplary embodiment as a pipe press. Instead of the embodiment as a pipe press, the power tool 1 may also be embodied as any other cutting or deformation tool. In particular, it is also possible for the power tool 1 according to the invention to be embodied as a dispensing apparatus for chemical substances, such as adhesive or plugging compound. Such dispensing apparatuses can also be referred to as dispensers.

[0041] As can be seen in FIG. 1, the power tool 1 embodied as a pipe press substantially has a housing 2, a tool fitting 3 and a power supply 4.

[0042] The housing 2 of the power tool 1 is of substantially cylindrical form and comprises a front end 2a, a rear end 2b, a left-hand side surface 2c, a right-hand side surface 2d (opposite 2c), an upper side 2e and a lower side 2f. A central part 2g of the housing 2 serves as a handgrip for allowing the power tool 1 to be held and controlled.

[0043] The energy supply 4 is positioned at the rear end 2b of the housing 2 of the power tool 1. In the present exemplary embodiment, the power supply 4 is in the form of a rechargeable battery (also referred to as power pack or battery). The power supply 4 in the form of a rechargeable battery may be detachably connected by means of an interface 5 to the rear end 2b of the housing 2 of the power tool 1. The power tool 1 or the electrical consumers of the power tool 1 is or are supplied with electrical power by means of the rechargeable battery 4.

[0044] In an alternative embodiment of the present invention, the power supply 4 of the power tool 1 may also be embodied as an electrical cable for connecting the power tool 1 to an electrical grid source (that is to say electrical socket).

[0045] The tool fitting 3 is positioned, for detachably receiving and holding a tool 6, at the front end 2a of the housing 2 of the power tool 1. In the present exemplary embodiment, a tool 6 in the form of a deformation tool is positioned at the tool fitting 3. In the present exemplary embodiment, the deformation tool 6 is embodied as a so-called pressing head. The deformation tool 6 embodied as a pressing head serves substantially for the processing and in particular deformation of lines, that is to say pipes and tubes.

[0046] An activation switch 7 is positioned on the lower side 2f of the housing 2 of the power tool 1. The power tool 1 can be started and stopped by means of the activation switch 7.

[0047] Substantially a drive 8, a drive shaft 9, an eccentric transmission device 10, an output shaft 11 (see, e.g., FIG. 3), a threaded spindle drive 12 and a linear actuator 13 are positioned in the interior of the housing 2 of the power tool 1. In the present exemplary embodiment, the drive 8 is embodied as a brushless electric motor.

[0048] As illustrated in FIGS. 2, 3, 6 and 7, the drive 8 embodied as a brushless electric motor is connected via the drive shaft 9 to the eccentric transmission device 10. By means of the connection to the drive shaft 9, a torque generated in the drive 8 is transmitted from the drive 8 to the eccentric transmission device 10.

[0049] A rotational speed ratio between the drive 8 and the output shaft 11 can be generated by means of the eccentric transmission device 10.

[0050] As shown especially in FIG. 4, the eccentric transmission device 10 furthermore substantially comprises a drive eccentric 14, an eccentric gear 15, a ring gear 16, and a compensating coupling 17. The drive eccentric 14 has a compensating weight 18 (also referred to as a balance weight or balancing weight), which is connected to the drive 8 via the drive shaft 9, cf. FIGS. 8 to 10. A bearing 30 is positioned between the drive eccentric 14 and the drive 8, cf. FIGS. 6 and 7. The eccentric gear 15 contains an aperture 15a for a ball bearing 19. The drive eccentric 14 is fitted into the ball bearing 19 and is thereby connected to the eccentric gear 15 for conjoint rotation therewith. Rotation of the drive eccentric 14 in the direction of rotation R also causes the eccentric gear 15 to rotate accordingly with a wobbling motion.

[0051] Moreover, the eccentric gear 15 is positioned in the ring gear 16. The ring gear 16 is connected to the inside of the housing 2 of the power tool 1 in a rotationally fixed manner. The eccentric gear 15 and the ring gear 16 have an involute toothing 20, cf. FIG. 5. The ring gear 16 has an inside diameter DH of 100 mm. According to an alternative embodiment, the inside diameter DH of the ring gear 16 can be between 20 and 200 mm.

[0052] Furthermore, the eccentric gear 15 contains a number of apertures 21 arranged in a circle around the drive eccentric 14. In the exemplary embodiment which is shown in the figures, the apertures 21 are in the form of eleven through holes. However, there may also be more or fewer than eleven through holes. According to an alternative embodiment, the apertures 21 can also be formed as blind holes.

[0053] In the present exemplary embodiment, the compensating coupling 17 is embodied as a parallel crank coupling with coupling elements 22. Each of the through holes 21 of the eccentric gear 15 serves to receive a coupling element 22 In the present exemplary embodiment, the coupling elements 22 are embodied as coupling pins.

[0054] The diameter DA of an aperture 21 embodied as a through hole is here twice as large as the diameter DK of a coupling element 22 embodied as a coupling pin.

[0055] The diameter of an aperture 21 here corresponds at least to the diameter of a coupling element 22 and to twice the value of the eccentricity E of the eccentric gear 15.

D.sub.apertureD.sub.coupling element+(2E) [0056] D.sub.aperture: diameter of the aperture [0057] D.sub.coupling element: diameter of the coupling element [0058] E: eccentricity of the eccentric gear.

[0059] The compensating coupling 17 may therefore be referred to as a parallel crank coupling or alternatively as a pin or crank coupling.

[0060] As can be seen in FIG. 4, the free end 22a of each coupling pin 22 projects from the through holes 21 of the eccentric gear 15 in arrow direction A. The free ends 22a of each coupling pin 22 are in turn connected to the output shaft 11 in such a way that a torque can be transmitted from the coupling pins 22 of the compensating coupling 17 to the output shaft 11.

[0061] The output shaft 11 has substantially a cylindrical shape. With the aid of a main bearing 23 and a secondary bearing 24, the output shaft 11 is mounted in the interior of the housing 2 of the power tool 1. The main bearing 23 is embodied as a rolling bearing or ball bearing, and the secondary bearing 24 is embodied as a sliding bearing. According to an alternative exemplary embodiment, both the main bearing 23 and the secondary bearing 24 can be embodied either as a rolling bearing or a sliding bearing. According to an alternative embodiment, it is also possible for just a single bearing to be provided.

[0062] As already described above, the output shaft 11 is connected to the compensating coupling 17 of the eccentric transmission device 10. The output shaft 11 adjoins the threaded spindle drive 12. Here, the threaded spindle drive 12 is connected to the output shaft 11. The rotational movement of the output shaft 11 can be converted into a linear movement by means of the threaded spindle drive 12.

[0063] As can be seen in particular from FIGS. 2 and 3, the threaded spindle drive 12 is connected to the linear actuator 13.

[0064] The linear actuator 13 comprises substantially a compression spring 25 and a thrust rod 26. Here, the compression spring 25 acts as a restoring spring for the linear actuator 13.

[0065] A force flow diverting device 27 is provided at the linear actuator 13. By means of the linear actuator 13 and the force flow diverting device 27, the linear force of the linear actuator 13 is transmitted to the tool fitting 3 such that the tool 6 in the form of a pressing head can be moved between an open and a closed position.

[0066] The drive 8, which is embodied as an electric motor, can rotate with a rotational speed value of between 10 000 and 30 000 rpm at a maximum extension and retraction speed of the linear actuator 13. In particular, a rotational speed value between 15 000 and 18 000 rpm is provided for the drive 8.

LIST OF REFERENCE SIGNS

[0067] 1 Power tool [0068] 2 Housing [0069] 2a Front end 2a of the housing [0070] 2b Rear end of the housing [0071] 2c Left-hand side surface of the housing [0072] 2d Right-hand side surface of the housing [0073] 2e Upper side of the housing [0074] 2f Lower side of the housing [0075] 3 Tool fitting [0076] 4 Power supply [0077] 5 Interface [0078] 6 Tool [0079] 7 Activation switch [0080] 8 Drive [0081] 9 Drive shaft [0082] 10 Eccentric transmission device [0083] 11 Output shaft [0084] 12 Threaded spindle drive [0085] 13 Linear actuator [0086] 14 Drive eccentric [0087] 15 Eccentric gear [0088] 15a Aperture in the eccentric gear [0089] 16 Ring gear [0090] 17 Compensating coupling [0091] 18 Compensating weight [0092] 19 Ball bearing [0093] 20 Involute toothing [0094] 21 Apertures in the eccentric gear [0095] 22 Coupling element [0096] 22a Free end on the coupling element [0097] 23 Main bearing [0098] 24 Secondary bearing [0099] 25 Compression spring [0100] 26 Thrust rod [0101] 27 Force flow diverting device [0102] 30 Bearing [0103] DA Diameter of an aperture [0104] DK Diameter of a coupling element [0105] DH Inner diameter of the ring gear [0106] E Eccentricity of the eccentric gear