EP4139092A1

EP4139092A1 - Electric hand-held power tool with ball catch coupling

Info

Publication number: EP4139092A1
Application number: EP21718861.4A
Authority: EP
Inventors: Sarah Cziepluch; Rory Britz; Bence Gabor SZUCS
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2020-04-23
Filing date: 2021-04-14
Publication date: 2023-03-01
Also published as: WO2021213857A1; EP3900881A1; CN115279552A; CN115279552B; US20230132195A1

Abstract

The invention relates to an electric hand-held power tool, in particular a hammer drill and/or chisel hammer, comprising a function control tube which can be actuated in order to produce different operational modes via a manual function selection switch, a guide tube which is equipped with a tool receiving area, and a ball catch coupling for transmitting a rotational movement from the functional control tube to the guide tube, wherein the ball catch coupling has a radial opening which is formed in the functional control tube, a main catch depression which is formed in the guide tube, a coupling ball which is mounted in the radial opening and is designed to engage into the main catch depression, and a spring-loaded conical ring, said coupling ball being capable of avoiding the actuating force of the conical ring in a radial direction. An additional depression differing from the main catch depression is formed in the guide tube, the opening angle of said additional depression being greater than the opening angle of the main catch depression.

Description

Electric hand machine tool with ball locking clutch

The present invention relates to an electric hand tool, in particular a hammer drill and / or chisel hammer. The hand machine tool is equipped with a function control tube that can be actuated via a manual function selector switch. This means that different operating modes, such as chisel positioning, chiselling, hammer drilling and drilling without impact, can be set. The handheld power tool has a guide tube that is equipped with a tool holder, and a ball locking coupling for transmitting a rotary movement from the functional control tube to the guide tube. The ball locking coupling has a radial opening formed in the function control tube, a preferably groove-shaped main locking recess formed in the guide tube, a coupling ball mounted in the radial opening and intended to engage in the main locking recess, and a spring-loaded conical ring. The coupling ball can deflect against an actuating force of the spring-loaded conical ring in the radial direction, based on the guide tube. If a tool received in the tool holder jams, the guide tube comes to a standstill. The function control tube, on the other hand, continues to be driven, for example in the hammer drilling operating mode. When the torque applied by the guide tube overcomes the actuating force of the spring-loaded conical ring, the coupling ball emerges from the main notch recess and is moved in the circumferential direction along the guide tube. In this way, damage to one or more transmission components of the handheld power tool can be prevented. If the torque applied by the guide tube falls below the actuating force of the spring-loaded conical ring, the coupling ball is pushed back into the main notch recess by the conical ring.

Hand machine tools of the type mentioned at the outset are basically known from the prior art.

The object of the present invention is to provide a handheld power tool that can be operated particularly reliably.

The object is achieved in that an additional recess different from the main notch recess is formed in the guide tube, the opening angle of which is greater than an opening angle of the main notch recess. A respective opening angle is preferably in a radial section plane of the guide tube. The radial section plane of the guide tube is preferably a section plane whose normal to the surface runs parallel, preferably coaxially, to the working axis (longitudinal axis) of the guide tube. It has been found to be advantageous if the opening angle of the fluff recess is between 70 degrees and 80 degrees, preferably 75 degrees. In a particularly preferred embodiment, the opening angle of the additional recess is greater than 90 degrees, preferably greater than 120 degrees.

The invention includes the knowledge that there are situations in which a coupling ball that has been moved out of the fluff recess, i. E. H. after a safety stop of the ball locking clutch, does not return to its intended position in the Flauptrastwellung, but rather comes to a standstill on a non-recessed surface of the guide tube. In this case, a radial force between the guide tube and the coupling ball is so great that the function adjusting tube can no longer be axially adjusted to effect the various operating modes of the machine tools. The additional recess provided according to the invention with a larger opening angle provides a defined position of the coupling ball on the surface of the guide tube, so that the functional control tube can be moved in the axial direction at any time.

It has been found to be advantageous if the additional recess is longer in the axial direction than the Flauptrast recess. In a particularly preferred embodiment, the downstroke recess and the additional recess are spaced apart from one another in the circumferential direction, based on the guide tube, by a web. It has been found to be advantageous if a web width of the web in the circumferential direction is less than 1 mm. The web width can be less than 0.5 mm. In a particularly preferred embodiment, the web width is 0.4 mm.

It has been found to be advantageous if an opening width of the additional recess related to a circumferential circle of the guide tube is greater than an opening width of the flauptrast recess related to the circumferential circle. The circumferential circle of the guide tube is preferably to be understood as a circle which runs along an outer surface of the guide tube and is tangent to all of the webs of the guide tube. The opening width of the flauptrast recess is preferably the arc length of that part of the circumference that spans the flauptrast recess. The opening width of the additional depression is preferably the arc length of the part of the circumferential circle spanning the additional depression.

In a particularly preferred embodiment, the downstairs recess and / or the additional recess are groove-shaped, preferably with a longer extension in the axial direction of the guide tube. A groove-shaped in particular The main notch recess can have a variable radius of curvature in the radial sectional plane and / or a flank section that is straight in sections. If this is the case, the opening angle of the main notch recess is preferably predetermined by that flank section of the main notch recess which has the longest extension in the radial direction. Alternatively, if the main notch depression, which is in particular groove-shaped, has a constant radius of curvature in the radial sectional plane, the opening angle of the main notch depression is preferably spanned by those secants which on the one hand touch the web and which intersect at the base of the main notch depression on the other.

An additional recess, in particular embodied in the form of a groove, can have a constant radius of curvature in the radial sectional plane. In this case, the opening angle of the main notch recess is preferably spanned by those secants which on the one hand touch the web and on the other hand intersect at the base of the main notch recess. Alternatively, an additional recess, in particular embodied in the form of a groove, can have a variable radius of curvature in the radial sectional plane and / or straight flanks in sections. In this case, the opening angle of the additional depression is preferably spanned by those secants which on the one hand touch the web and on the other hand intersect at the base of the additional depression. In a particularly preferred embodiment, several main notch recesses and several additional recesses are provided on the guide tube. It has been found to be advantageous if the main detent depressions and the additional depressions alternate along the circumferential direction of the guide tube.

It has been found to be advantageous if the conical ring has a first conical shoulder and a second conical shoulder that is different from the first conical shoulder. Particularly preferably, the first conical shoulder and the second conical shoulder have different angles of inclination with respect to the axial direction. It has been found to be advantageous if the first conical shoulder, namely that conical shoulder which extends further away from the guide tube in the radial direction, has an angle of inclination between 50 degrees and 60 degrees, preferably 55 degrees. The second conical shoulder preferably has an angle of inclination between 35 degrees and 45 degrees, preferably 38 degrees. In a further preferred embodiment, the radial opening in the functional adjusting tube has a cylindrical passage and / or a conical bevel. The conical bevel particularly preferably has a cone angle between 15 degrees and 25 degrees, preferably 20 degrees, the cone angle being related to the radial direction. In a particularly preferred embodiment, the electric handheld power tool is designed as a battery-operated combination hammer. The maximum working torque that can be transmitted via the ball locking coupling (the coupling balls are paired with the main locking depressions) is preferably between 30 and 40 Newton meters. An axial force to be applied for an axial displacement of the functional adjusting tube is preferably between 30 and 100 Newtons, in particular between 35 and 45 Newtons. A torque required to overcome the additional depressions (the coupling balls are paired with the additional depression) is preferably at most 50 percent, particularly preferably at most 20 percent of the maximum working torque that can be transmitted via the ball locking clutch. The invention is also achieved by a guide tube for an electric hand tool, in particular for a hammer drill and / or chisel hammer, the guide tube having a main notch recess for at least partial engagement of a coupling ball and an inner volume for receiving an exciter piston of an impact mechanism. An additional recess different from the main notch recess is formed in the guide tube, the opening angle of which is greater than an opening angle of the main notch recess. The guide tube according to the invention can be configured in a corresponding manner by the exemplary embodiments described with reference to the electric hand tool.

Further advantages emerge from the following description of the figures. Various exemplary embodiments of the present invention are shown in the figures. The figures, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations. In the figures, the same and similar components are numbered with the same reference numerals. Show it:

1A shows a first exemplary embodiment of a flange machine tool according to the invention; 1B shows a sectional view through the flange machine tool; 2A shows a side view of a guide tube with section line A-A according to a first preferred embodiment;

FIG. 2B shows a sectional view A-A (radial sectional plane) from FIG. 2A; FIG. 3A shows a side view of a guide tube with section line A-A according to a second preferred exemplary embodiment;

3B shows a sectional view AA (radial sectional plane) from FIG. 3A; 4A shows a preferred exemplary embodiment of a ball locking coupling; 4B shows a radial opening in the function adjusting tube; 4C shows a conical ring with a first and second conical shoulder; and FIG. 5 shows the flange machine tool of FIG. 1 in a different operating mode.

Examples of execution:

A first preferred exemplary embodiment of an electric handheld power tool 100 according to the invention is shown in FIG. 1A. The handheld power tool 100 is designed, for example, as a combination hammer. The handheld power tool 100 is equipped with a manual function selector switch 10 via which various operating modes of the handheld power tools 100 can be set. For example, FIG. 1B shows a section through the handheld power tool 100 in the hammer drilling BH operating mode, whereas FIG. 5 shows an exemplary section through the handheld power tool 100 in the chiseling ME operating mode.

The electric hand machine tool 100 is equipped with a cylindrical guide tube 30 that has a tool holder 35. A chisel 36, which is only shown in sections in FIG. 1B, is received in the tool holder 35. The hand-held power tool 100 has a function control tube 10 that can be moved in the axial direction AR via the said manual function selector switch 20 to effect different operating modes. The cylindrical function control tube 10 is arranged coaxially to the guide tube 30.

The handheld power tool 100 is also equipped with a pneumatic hammer mechanism 50 which has an exciter piston 51 which is movable in the axial direction AR along a working axis AX within the guide tube 30. The exciter piston 51 is coupled via a connecting rod 53 to an impact mechanism eccentric wheel 55, which is driven by an electric motor, not shown here. By means of the exciter piston 51, a periodic hammer mechanism pressure can be generated within the guide tube 30, since in the hammer drilling BH operating mode shown in FIG.

Both the function control tube 20 and the guide tube 30 are rotatably mounted about the working axis AX in a housing 90 of the handheld power tool 100. In order to set the function control tube 20 into rotation about the working axis AX, the handheld power tool 100 has a bevel pinion 23, which can be driven by the electric motor, not shown here. The bevel pinion 23 in turn drives a bevel ring 25, with which the functional adjusting tube 20 - at least in the hammer drilling BH operating mode shown in FIG. 1 - is positively engaged in the circumferential direction UR.

The handheld power tool 100 furthermore has a ball locking coupling 40 for transmitting the rotary movement from the functional adjusting tube 20 to the guide tube 30. This is the Ball locking coupling 40 is equipped with a radial opening 42 formed in the function adjusting tube 20. The ball locking coupling 40 also has a coupling ball 45 mounted in the radial opening 42. The coupling ball 45 is intended to engage in a main notch recess 43 which is formed in the guide tube 30. If the coupling ball 45 is in engagement with the main notch recess 43, a rotary movement can be transmitted from the functional adjusting tube 20 to the guide tube 30. In the exemplary embodiment shown here, the guide tube 30 has a plurality of main notch depressions 43 which are formed on the guide tube 30 in the circumferential direction UR. Accordingly, a plurality of coupling balls 45 and, as it were, a plurality of radial openings 42 are also provided. The ball latching coupling 40 has a conical ring 47 which is spring-loaded by means of the spring 48 and against the actuating force AF of which the coupling balls 45 can deflect outward in the radial direction RR.

FIG. 2 shows a first preferred exemplary embodiment of a guide tube 30. The guide tube 30 is intended for an electric handheld power tool from FIG. 100 (see FIG. 1). 2A shows the guide tube 30 in a side view with the drawn section line A-A. Section A-A (radial section plane) is shown in FIG. 2B. The guide tube 30 has six main notch recesses 43 which are arranged on the guide tube 30 in the circumferential direction UR. Alternating with the main notch recesses 43, six additional recesses 44 are formed in the guide tube 30.

As can be seen from FIG. 2B, the groove-shaped main notch recess 43 does not have a constant radius of curvature in the radial section plane AA. The opening angle W1 of the main notch recess 43 is predetermined by that flank section 43 'of the main notch recess 43 which has the longest extension in the radial direction RR. The opening angle W1 of the main notch recess 43 is, for example, 75 degrees. As can also be seen from FIG. 2B, the groove-shaped additional recess 44 has a constant radius of curvature KR. An opening angle W2 of the additional recess 44 is spanned in the radial section plane AA by those secants SK which on the one hand touch the web 46 and on the other hand intersect at the base point (the “lowest” point) of the additional recess 43. The opening angle W2 of the additional recess 44 is designed, for example, to be 135 degrees. Thus, the opening angle W2 of the additional recess 44 is greater than the opening angle W1 of the main notch recess 43. Due to the comparatively smaller opening angle W1 of the main notch recess 43, the main notch recess 43 is used to actually transfer a working torque from the function control tube 20 (see Figure 1 B) to the guide tube 30. The Additional specialization 44 is only intended to offer the coupling ball 45 a defined position along the circumferential direction UR of the guide tube 30, so that - regardless of the rotational position of the guide tube 30 - a displacement of the function control tube 20 in the axial direction AR is possible.

As can also be seen in FIG. 2, the additional recess 44 has an additional detent length LZ in the axial direction AR, which is greater than a flauptrast length LH of the flauptrast recess 43. Furthermore, the additional recess 44 is spaced apart from the flauptrast recess 43 in the circumferential direction UR by a web 46. For example, the web 46 has a thickness of 0.4 mm in the circumferential direction UR. It is clear that, due to the small web thickness of the web 46, the coupling ball 45 (not shown in FIG. 2) comes to rest either in the Flauptrast recess 43 or the additional recess 44.

FIG. 2B shows that an opening width OW2 of the additional recess 44 based on a circumferential circle UK of the guide tube 30 is greater than an opening width OW1 of the flauptrast recess 43 based on the circumferential circle UK Guide tube is tangent. The opening width OW1 of the flauptrast recess 43 corresponds to the arc length of the part UK1 of the circumferential circle UK spanning the flauptrast recess 43. The opening width of the additional depression OW corresponds to the arc length of the part UK2 of the circumferential circle UK spanning the additional depression 44.

FIG. 3 shows a second preferred exemplary embodiment of a guide tube 30. The guide tube 30 is intended for an electric flange machine tool of 100 (see FIG. 1). 3A shows the guide tube 30 in a side view with the section line A-A drawn. Section A-A (radial section plane) is shown in FIG. 3B. The guide tube 30 has six Flauptrast depressions 43, which are arranged in the circumferential direction UR on the guide tube 30. In the guide tube 30, six additional depressions 44 are formed in alternation to the flauptrast depressions 43.

The fluff depressions 43 of the exemplary embodiment in FIG. 3 are identical to the fluff depressions 43 of the exemplary embodiment in FIG. Correspondingly, the opening angle W1 of the fluff recess 43 is predetermined by that flank section 43 'of the fluff recess 43 which has the longest extension in the radial direction RR. In contrast to the embodiment of FIG. 2, the additional recess 44 of the guide tube 30 of FIG. 3 is stepped, ie in particular the additional recess 44 has two at least partially straight flanks 44 'and thus no constant radius of curvature. The opening angle W2 of the additional recess 44 is determined by the two at least in sections straight flanks 44 'spanned. The opening angle W2 of the additional recess 44 is designed, for example, to be 135 degrees. Thus, the opening angle W2 of the additional recess 44 is greater than the opening angle W1 of the main notch recess 43.

A preferred embodiment of a ball locking coupling 40 is shown in Figure 4A. The ball locking coupling 40 serves to transfer the rotary movement from the functional adjusting tube 20 to the guide tube 30. For this purpose, the ball locking coupling 40 is equipped with a radial opening 42 formed in the functional adjusting tube 20. The ball locking coupling 40 also has a coupling ball 45 mounted in the radial opening 42. The coupling ball 45 is intended to engage in a main notch recess 43 which is formed in the guide tube 30. The ball locking coupling 40 has a conical ring 47 spring-loaded by means of the spring 48, against whose actuating force AF the coupling ball 45 can deflect outward in the radial direction RR (upward in FIG. 4).

As can be seen from FIG. 4B, the radial opening 42, which is formed in the function adjusting tube 20 (see FIG. 4A), has a cylindrical passage 42 'which is oriented coaxially to the radial direction RR. On the side of the radial opening 42 facing away from the guide tube 30, a conical bevel 42 ″ is formed, which has, for example, a cone angle KW of 20 degrees, based on the radial direction RR. This conical bevel 42 ″ makes it easier for the coupling ball 45 to emerge in the radial direction outward (compare FIG. 4A, movement of the coupling ball 45 upwards).

FIG. 4C now shows a preferred embodiment of the spring-loaded conical ring 47. The conical ring 47 has a first conical shoulder 47a and a second conical shoulder 47b. The first conical shoulder 47a and the second conical shoulder 47b have different angles of inclination N1, N2 with respect to the axial direction AR. The first conical shoulder 47a, namely that conical shoulder which extends further away from the guide tube 30 in the radial direction RR, has, for example, an inclination angle N1 of 55 degrees. The second conical shoulder 47b has, for example, an inclination angle N2 of 38 degrees. By forming the spring-loaded conical ring 47 with the first conical shoulder 47a and the second conical shoulder 47b, in combination with the conical bevel 42 ″, an axial actuating force required for the movement of the functional adjusting tube 20 can be significantly reduced. At the same time, it has been shown that a release torque realized by the ball locking clutch 45 is only minimally reduced.

Finally, FIG. 5 shows the handheld power tool 100 of FIG. 1 in the chiselling ME operating mode. The handheld power tool 100 of FIG. 5 is also equipped with a pneumatic hammer mechanism 50, which has an exciter piston 51 which is movable in the axial direction AR along a working axis AX within the guide tube 30. The exciter piston 51 is coupled via a connecting rod 53 to a striking mechanism eccentric wheel 55, which is driven by an electric motor, not shown here. By means of the exciter piston 51, a periodic impact mechanism pressure can be generated within the guide tube 30, since a ventilation opening 31 of the guide tube 30 is closed by the function control tube 20 in the chiselling ME operating mode shown in FIG.

Both the function control tube 20 and the guide tube 30 are rotatably mounted about the working axis AX in a housing 90 of the handheld power tool 100. In the chiselling ME operating mode, a rotation of the guide tube 30 is not desired. Correspondingly, in the chiseling ME operating mode, the function control tube 20 is not driven to rotate about the working axis AX. Although the bevel pinion 23 continues to drive the bevel ring 25 already known from FIG. 1B, it is not in positive engagement with the functional adjusting tube 20 - based on the circumferential direction UR. This is because the function control tube 20 is displaced in the direction of the tool holder 35 (to the left in FIG. 5) by the function selector switch 10 (see FIG.

Reference list

10 function selector switch

20 function control tube

23 bevel pinions

25 cone rim

27 spur gearing

30 guide tube

31 Vent

35 tool holder

36 chisels

40 Ball locking coupling

42 radial breakthrough

42 ‘cylindrical passage 42“ conical bevel

43 Flauptrast indentation

43 ‘flank section

44 Additional specialization

44 ‘flanks

45 coupling ball

46 bridge

47 conical ring

47a first conical shoulder

47b second tapered shoulder

48 compression spring

50 striking mechanism

51 exciter piston

53 connecting rods

55 Impact mechanism eccentric wheel 90 housing

100 electric hand tool AF positioning force

AR axial direction

AX working axis

BH operating mode hammer drilling

FP base point

KW cone angle

KR radius of curvature

LH main grid length

LZ additional rest length

ME Chiseling operating mode

N1 angle of inclination of the first tapered shoulder

N2 angle of inclination of the second tapered shoulder

OW1 Opening width of the main notch recess

OW2 Opening width of the additional recess

RR radial direction

SK secant

UK circumference

UK1 Proportion of the circumferential circle above the main recess UK2 Proportion of the circumferential circle above the additional recess UR circumferential direction

W1 opening angle of the main notch recess

W2 opening angle of the additional recess

Claims

1. Electric hand tool (100), in particular hammer drill and / or chisel hammer, with a function control tube (10) which can be actuated via a manual function selector switch (20) to effect various operating modes (ME, BH), one equipped with a tool holder (35) Guide tube (30), and with a ball locking coupling (40) for transferring a rotary movement from the functional adjusting tube (20) to the guide tube (30), the ball locking coupling (40) having a radial opening (42) formed in the functional adjusting tube (20), one in the Guide tube (30) formed main detent recess (43), a coupling ball (45) mounted in the radial opening (42) and intended to engage in the main detent recess (43), as well as a spring-loaded conical ring (47) against whose actuating force (AF) the The coupling ball (45) can evade in the radial direction (RR), characterized in that in the guide tube (30) an additional recess different from the main notch recess (43) ng (44) is formed whose opening angle (W2) is greater than an opening angle (W1) of the main notch recess (43).

2. Hand machine tool (100) according to claim 1, characterized in that the opening angle (W1) of the main notch recess (43) is between 70 degrees and 80 degrees, preferably 75 degrees and / or that the opening angle (W2) of the additional recess (44) is greater than 90 degrees, preferably greater than 120 degrees.

3. Hand machine tool (100) according to claim 1 or 2, characterized in that the additional recess (44) in the axial direction (AR) is longer than the main notch recess (43).

4. Hand machine tool (100) according to one of the preceding claims, characterized in that the main notch recess (43) and / or the additional recess (44) are groove-shaped in the axial direction (AR).

5. Hand machine tool (100) according to one of the preceding claims, characterized in that an opening width (OW2) of the additional recess (44) related to a circumferential circle (UK) of the guide tube (30) is greater than an opening width (OW1) of the main notch recess (43) related to the circumferential circle (UK).

6. Hand machine tool (100) according to one of the preceding claims, characterized in that the main notch recess (43) and the additional recess (44) are spaced apart in the circumferential direction (UR) of the guide tube (30) by a web (46), the web ( 46) preferably has a web width of less than 1 millimeter.

7. Hand machine tool (100) according to one of the preceding claims, characterized in that the tapered ring (47) has a first tapered shoulder (47a) and a second tapered shoulder (47b) which have different angles of inclination (N1, N2) with respect to the axial direction (AR) exhibit.

8. Hand machine tool (100) according to one of the preceding claims, characterized in that the radial opening (42) has a cylindrical

Has passage (42 ‘) with a conical bevel (42 ″), which preferably has a cone angle (KW) of 20 degrees.

9. Hand machine tool (100) according to one of the preceding claims, characterized in that the radial opening (42) has a cylindrical

Has passage (42 ‘) with a conical bevel (42"), which is preferably 20 degrees.

10. Hand machine tool (100) according to one of the preceding claims, characterized in that a plurality of main detent depressions (43) and several

Additional recess (44) are provided, which alternate along the circumferential direction (UR) of the guide tube (30).

11. Guide tube (30) for an electric hand tool (100), in particular a hammer drill and / or chisel hammer, the guide tube having a main notch recess (43) for at least partial engagement of a coupling ball (45) and an inner volume for receiving an exciter piston (51) of a striking mechanism (50), characterized in that an additional recess (44) different from the main notch recess (43) is formed in the guide tube (30), the opening angle (W2) of which is greater than an opening angle (W1) of the main notch recess (43).