EP3317049A1

EP3317049A1 - Hand-held power tool comprising a safety coupling

Info

Publication number: EP3317049A1
Application number: EP16733463.0A
Authority: EP
Inventors: Erwin Manschitz; Philipp Lorenz; Azize Cengil
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2015-06-30
Filing date: 2016-06-28
Publication date: 2018-05-09
Also published as: US20180169847A1; EP3112087A1; WO2017001363A1; CN107427995A

Abstract

Hand-held power tool (100), in particular hammer drill or combined hammer, comprising a safety coupling (2) via which torque transmission between a motor shaft (7) and a transmission shaft (8) of the hand-held power tool (100) can be established and interrupted; the safety coupling (2) includes a coupling part (11) at the input end and a coupling part (12) at the output end and can be actuated by a coupling actuator; mutually complementary driving profiles (1, 1'), in particular similar to a crown gear set, by which the coupling part (11) at the input end and the coupling part (12) at the output end can be interlocked, are arranged on the coupling part (11) at the input end and on the coupling part (12) at the output end.

Description

"Hand tool with safety coupling"

The present invention relates to a hand tool, in particular rotary hammer or combination hammer, with a safety clutch via which a torque transmission between a motor shaft and a gear shaft of the power tool can be manufactured and interrupted. The safety coupling has a drive-side coupling part and a driven-side coupling part. The safety coupling can be actuated via a clutch actuator.

Hand tool machines of the type mentioned are basically known from the prior art. The safety clutch encompassed by the handheld power tool primarily serves the safety of a user of the power tool by virtue of the fact that, in the case of blocking a tool clamped in the power tool, the clutch is opened and thus torque transmission between the motor shaft and the gear shaft is interrupted. This can be reduced resulting from the blocking of the tool deflection of the power tool.

It is an object of the present invention to provide a hand tool whose safety clutch avoids undesirable deflection in the case of blocking the tool as far as possible and is particularly lightweight and compact.

The object is achieved in that mutually complementary driver profiles are arranged on the drive-side coupling part and on the driven-side coupling part, in particular in the manner of a crown gear toothing, via which the drive-side coupling part and the driven-side coupling part can be frictionally / positively coupled.

The invention includes the recognition that in hand tooling machines of the prior art, for example, have a frictional safety coupling, although a short opening time and a self-opening of the safety clutch is realized, but with the disadvantage of a comparatively high weight and a relatively large space of the safety coupling , This is to be regarded as disadvantageous for a hand tool.

The inventively provided complementary Mitnehmerprofile a safety clutch is provided which has both a short opening time and a self-opening function and thereby compared to a frictional clutch at the same space can transmit significantly higher torques. Thus, both a lightweight and compact safety coupling is provided. In addition, the safety coupling according to the invention can be constructed particularly simple and can be dispensed with any electrical engine braking in the power tool.

The invention further includes the knowledge that due to the price and easy controllability of hand tool machines are often provided with electric motors with carbon brushes. In hand tool machines of the prior art typically complicated motor brake devices are provided to avoid the brush wear in the course of a sudden deflection of the power tool. As already mentioned, the mutually complementary Mitnehmerprofile, which are arranged on the drive-side coupling part or on the output-side coupling part, be designed in the manner of a crown gear teeth. Preferably, any end faces of the coupling parts are free of Mitnehmerprofilen. Preferably, the mutually complementary driver profiles are annular. Particularly preferably, the driver profiles each have wedge elements which protrude axially to the coupling direction of the driver profile. Under axial is to be understood in the context of the present invention oriented parallel to the direction of coupling direction.

According to an advantageous embodiment, the height of a wedge element can be between 0.3 mm and 1 mm. A height of a wedge element of 0.5 mm is to be regarded as particularly advantageous. The height of a wedge element is to be regarded as the maximum extension of a wedge element from the drive-side or driven-side coupling part.

In a particularly preferred embodiment, the wedge elements are asymmetrical. By thus configured wedge elements, the stroke or the distance for connecting the drive-side coupling part to the output-side coupling part can be significantly reduced. As a result of this reduction in the stroke or distance, the clutch actuator or the force required for closing the clutch force of the clutch actuator can be significantly reduced compared to the prior art. Consequently, a total of a particularly low overall height of the safety clutch can be made possible.

Characterized in that the complementary Mitnehmerprofile may be formed in the manner of a crown gear or by the fact that the wedge elements can protrude axially to the coupling direction results in applied torque and unactuated clutch actuator, a self-opening of the safety clutch. This is because an axially acting clutch opening force acts on the safety clutch. By the short produced Opening time of the safety coupling, a small deflection angle of the power tool is achieved in the case of blocking of the tool, whereby the safety of the user is significantly increased.

It has proved to be advantageous if the drive-side coupling part is fastened to a drive-side flange of the safety coupling via an elastic element that can be deflected elastically in the coupling direction. Alternatively, the driver profile arranged on the drive-side coupling part can be fastened to the drive-side coupling part via a spring element that can be deflected elastically in the coupling direction. Preferably, the drive-side flange is rotatably connected to the motor shaft.

The output-side coupling part can be fastened to an output-side flange of the safety coupling via an elastic element deflectable elastically in the coupling direction. Alternatively, the driving profile arranged on the output side coupling part may be fastened to the output side coupling part via a spring element elastically deflectable in the coupling direction in the coupling direction. Preferably, the output-side flange is rotatably connected to the transmission shaft.

The spring element may preferably be installed biased in such a way that the mutually complementary driver profiles are spaced apart from each other when the clutch actuator is unactuated, that is, the safety clutch is disengaged.

Alternatively, the driving profile arranged on the output side coupling part can be fastened to the output side coupling part via a spring element that can be deflected elastically in the coupling direction. Again, preferably, the spring element is installed biased so that the mutually complementary Mitnehmerprofile are spaced apart from each other with unactuated clutch actuator.

It has proved to be advantageous if the drive-side coupling part is mounted axially movable to the coupling direction or the driven-side coupling part is mounted axially movable to the coupling direction.

In a particularly preferred embodiment, the motor shaft and the transmission shaft are arranged coaxially with each other. Similarly, the output-side coupling part and the drive-side coupling part can be arranged coaxially with one another and preferably in turn can be arranged coaxially to the motor shaft and transmission shaft. Particularly preferably, the ring-shaped Mitnehmerprofile coaxial with the motor shaft and the transmission shaft are arranged. As a result, the safety coupling can be provided in a particularly compact manner. It has proven to be advantageous if the clutch actuator is an electromagnetic actuator with an actuator coil.

Due to the inventive design of the drive-side and output-side coupling part with a mutually complementary driver profile in particular for the designed as an electromagnetic actuator Kupplungsaktuator necessary stroke or the distance for connecting the drive-side coupling part with the driven-side coupling part can advantageously be significantly reduced, since the length of the hub or the distance to close the clutch is an adverse resistance to the magnetic flux of the clutch actuator designed as an electromagnetic actuator. As a result of this reduction in the stroke or travel distance, the clutch actuator designed as an electromagnetic actuator or the magnetic force of the clutch actuator designed as an electromagnetic actuator can be significantly reduced in comparison with the prior art for the closing of the clutch.

Preferably, the electromagnetic actuator is designed and arranged to actuate the armature-acting drive-side coupling part or acting as an anchor output-side coupling part, preferably to operate without contact. Advantageously, it is therefore possible to dispense with a force transmission element between actuator coil and driver profile, in particular a rigid force transmission element arranged serially in the force flow, such as a lever arm or the like.

Alternatively or additionally, the electromagnetic actuator may be designed and arranged to actuate the armature profile acting as an armature without contact.

The driver profile, the drive-side coupling part and / or the output side coupling part may be soft magnetic. Alternatively, the driver profile, the drive-side coupling part and / or the output side coupling part may be hard magnetic. In a further preferred embodiment, the safety coupling is open when normally switched actuator coil. Thus, therefore, the elastically deflectable spring element, which is installed biased, sufficient to keep the complementary Mitnehmerprofile spaced from each other when the actuator coil is de-energized. In the opposite case, when energized actuator coil, which acts through the actuator coil acting as an anchor driver magnetic force is large enough to compensate for the spring force of the spring element and to keep each other complementary Mitnehmerprofile for the purpose of torque transmission in positive engagement. Alternatively, the safety clutch may be closed when normally switched actuator coil. The actuator coil may be arranged fixed to the frame to a housing of the power tool. Alternatively, the actuator coil can be arranged rotationally fixed to the motor shaft. A non-rotatable connection can for example be non-positively or positively. Preferably, a rotationally fixed to the motor shaft provided actuator coil is supplied via a sliding contact with a control current. The sliding contact may preferably be realized via at least one slip ring and at least one brush, which are preferably arranged in pairs.

The hand tool machine may have an electronic unit for detecting a sudden deflection of the hand tool, wherein the electronic unit is designed and arranged to switch the actuator coil de-energized when a sudden deflection of the power tool is detected. Alternatively, the power tool may have an electronic unit for detecting a sudden deflection of the power tool, wherein the electronic unit is designed and arranged to energize the actuator when a sudden deflection of the power tool is detected.

Alternatively, or in addition to the electronic unit for detecting a sudden deflection of the power tool, an electronic unit for detecting an angular acceleration of at least one component and / or the entire of the hand tool may be provided, thereby closing an abrupt deflection of the power tool. In this case, the electronic unit is designed to detect an angular acceleration and arranged to switch the actuator coil de-energized when an angular acceleration of at least one component and / or the entire of the hand tool is detected. Alternatively, the handheld power tool can have an electronic unit for detecting an angular acceleration of at least one component and / or the entire of the handheld power tool in order thereby to conclude a sudden deflection of the handheld power tool. In this case, the electronic unit is designed and arranged to energize the actuator coil when an angular acceleration of at least one component and / or the entire of the handheld power tool is detected.

According to a further embodiment, the handheld power tool can have an electronic unit for detecting a change in at least one predetermined physical size of the handheld power tool, wherein the change in the at least one predetermined physical variable serves as a reason or indication of a sudden deflection of the handheld power tool and consequently for opening the safety clutch. The electronic unit for detecting a change of at least a predetermined physical quantity is formed and arranged the actuator coil to de-energize when a change of at least one predetermined physical quantity is detected. Alternatively, the handheld power tool may include an electronics unit for detecting a change in at least one predetermined physical size of the handheld power tool, wherein the electronics unit is configured and arranged to energize the actuator coil when a change in at least one predetermined physical size of the handheld power tool is detected.

Further advantages will become apparent from the following description of the figures. In the figures, various embodiments of the present invention are shown. 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, identical and similar components are numbered with the same reference numerals. It shows:

1 shows a first embodiment of a hand tool according to the invention;

FIG. 2 shows a driver profile of the safety coupling of the handheld power tool of FIG. 1; FIG.

3a shows a schematic representation of a right-angled driving profile in a safety coupling according to the prior art;

Fig. 3b is a schematic representation of a driving profile with wedge elements of a

Safety coupling of a hand tool according to the invention;

Fig. 3c is a graphical comparison of the biasing forces of a spring element in a

Safety coupling according to the prior art and a spring element in a safety coupling of a hand tool according to the invention;

4 shows a further embodiment of a safety coupling of a hand tool according to the invention; and

Fig. 5 shows another embodiment of a safety coupling of a hand tool of the invention.

EXAMPLES

A hand tool 100, in this case a hammer drill, is shown in FIG. The hand tool 100 has a housing 13 in which an electric drive motor 6 and a safety clutch 2 are arranged. The electric drive motor 6 is connected to the safety clutch 2 via the motor shaft 7. The safety clutch 2 is connected via the gear shaft 8 and a gear, not shown, with a recorded in the power tool 100 tool 4, in this case a drill. The tool 4 is inserted in a wall 5 to be processed.

About the safety coupling 2, a torque transmission between the motor shaft 7 and the transmission shaft 8 of the power tool 100 can be made and interrupted. According to the invention, the safety coupling 2 has complementary driver profiles, one of which will now be explained with reference to FIG. 2.

As can be seen from Fig. 2, the driver profile 1 is annular and has axially, that is parallel to the coupling direction KR projecting wedge elements K on. In the presently illustrated embodiment, a plurality of wedge elements K are arranged uniformly spaced from one another along the annular driver profile. As can also be seen from Fig. 2, the driver profile 1 is formed in the manner of a crown gear, that is, in particular, the radial side surfaces of the driver are free of any teeth and free of wedge elements. The direction of rotation R of the driver profile 1 during normal operation of the power tool is designated accordingly.

The wedge element K has a height H of about 0.5 mm. However, it is also possible that the height H of the wedge member K is in a range of 0.3 to 1 mm. In addition, however, it is also possible that the height H has a value greater than 1 mm or a value less than 0.3 mm.

In the magnification shown at the bottom left in FIG. 2, an asymmetrical design of the wedge elements K can be clearly seen. A steep Mitnehmerflanke MF, which is leading in the direction of rotation R, is steeper than a trailing edge in the direction of rotation R NF.

3a shows a schematic representation of a right-angled driving profile in a safety coupling according to the prior art. 3b shows a schematic representation of a driving profile with wedge elements K of a safety coupling of a hand tool according to the invention. The spring element 10 serves for separating or opening the respective safety clutch. In the case of the right-angled entrainment profile in the safety coupling according to the prior art, the spring element 10 must actively pull apart the two load-bearing coupling parts, ie the drive-side coupling part and the output-side coupling part. Because of the relatively large frictional force resulting from the applied normal force, a spring element 10 with a relatively large spring force F _A must be used in order to be able to disconnect or open the safety clutch. It is necessary that this spring force F _A at a stroke of h = 0, ie at an open clutch and shortly before the contact of the two coupling parts, already must be present. It is thus necessary a relatively high bias in the spring element 10 in the safety coupling according to the prior art. If in the safety coupling according to the prior art, a magnet is used to connect or close the two coupling parts, this magnet must be chosen so that it can generate the relatively large spring force F _A with the clutch open. Consequently, a relatively large or strong magnet must be chosen in order to close the clutch against the spring force F _{A of} the relatively large spring element can.

In contrast, due to the Mitnehmerprofils 1 in the manner of a crown gear with wedge elements K a significantly smaller or weaker spring element can be selected with a much lower spring force F _B for a safety coupling of a hand tool of the invention. Theoretically, the spring force F _{B of} the spring element 10 can be independent of the opening of the clutch, since an opening axial force for opening or separating the two coupling parts, ie the drive-side coupling part from the driven-side coupling part is already generated because of the wedge elements K under load. The spring element 10 thus serves only to keep the two coupling parts out of engagement. As a result, a relatively small or weak spring element can be selected, which has a spring force F _B smaller than the spring force F _A (see Fig. 3c). A sectional view of a safety coupling 2 of a hand tool according to the invention is shown in FIG. 4. FIG. 4 shows the engaged state EK of the safety clutch 2. In the engaged state EK, a torque transmission between a motor shaft 7 and a transmission shaft 8 can take place.

The safety coupling 2 has a drive-side coupling part 1 1 and a driven-side coupling part 12. On the drive-side coupling part 11, a ring-shaped driver profile 1 (see Fig. 2) is arranged. A complementarily designed and annular driver profile V (see Fig. 2) is arranged on the output-side coupling part 12. The output-side coupling part 12 is rotationally fixed to the transmission shaft 8, for example, non-positively or positively connected. The drive-side coupling part 1 1, the Carrier of the annular driver profile 1 is axially movably mounted in the coupling direction KR. The storage takes place via an elastically deflectable spring element 10, via which the drive-side coupling part 11 is connected to the driver profile 1 arranged thereon with a drive-side flange 9. The drive-side flange 9 is in turn rotatably connected to the motor shaft 7.

4, a ball bearing between the motor shaft 7 and gear shaft 8 is provided in the drive-side flange 9 in which the transmission shaft 8 is mounted. This facilitates the alignment of motor shaft 7 and gear shaft. 8

As already mentioned, in Fig. 4, the engaged state EK is shown. A torque which is applied via the electric drive motor, not shown here, passes from the motor shaft 7 to the rotatably connected to the motor shaft 7 drive-side flange 9 and from there via the axially elastically deflectable in the coupling direction KR spring element 10 on the drive-side coupling part 1 first

The drive-side coupling part 1 1, which in the present case is axially movably mounted to the coupling direction KR, transmits the torque to the output-side coupling part 12, which in turn has a complementary driver profile V. About the output side coupling part 12, which is fixedly secured to the transmission shaft 8, the torque reaches a gear, not shown here. The transmission shaft 8 is rotatably mounted in a housing 13 of the power tool.

As can also be seen from FIG. 4, the motor shaft 7, the transmission shaft 8, the respective driver profiles 1, V, which are of annular design and complementary to one another, are arranged coaxially with one another.

Hereinafter, a coupling operation with respect to the clutch actuator is explained in detail. The clutch actuator is in the present case an electromagnetic actuator with an actuator coil 15, which is arranged fixed in position relative to the housing 13 via a coil holder 14. To protect the actuator coil 15, this is surrounded by an insulating layer 16.

By acting on the actuator coil 15 with a control current, the drive-side coupling part 11 is pulled to the output-side coupling part 12 and thus the complementary driver profiles 1, 1 ', as shown in Fig. 4, engaged.

The hand tool machine may have an electronic unit for detecting a sudden deflection of the hand tool, wherein the electronic unit is formed and arranged to switch the actuator coil 15 de-energized when a sudden deflection of the power tool is detected. In this case, the electronic unit can be formed be formed and arranged to detect an angular acceleration and / or a predetermined change of at least one physical size of at least one component and / or the entire of the power tool to thereby detect a sudden deflection of the power tool.

Due to the biased built-in spring element 10 and the axial force generated by the wedge elements K, the drive-side coupling part 1 1 is moved away from the output side coupling part 12 and the complementary driver profiles 1, V separated from each other, so that a torque transmission between the motor shaft 7 and the Transmission shaft 8 is interrupted.

Another embodiment of a safety coupling 2 of a hand tool is shown in Fig. 5. By the safety coupling 2 shown in Fig. 5, a torque transmission between a motor shaft 7 and a transmission shaft 8 is to take place. In contrast to the embodiment of FIG. 4, in which the actuator coil 15 is fixed to the housing 13 of the power tool, the actuator coil 15 is mounted in a coil holder 14 in the embodiment of FIG. 5, wherein the coil holder 14 is rotatably mounted to the motor shaft 7. Correspondingly, the actuator coil 15 rotates together with the motor shaft 7 in the direction of rotation R. In order to enable the coil to be energized, the coil holder 14 has pairs of slip rings 23 in the circumferential direction, which are electrically connected to the actuator coil 15. The paired slip rings 23 are in a sliding contact with a frame-fixed brush pair 24, so that the actuator coil 15 can be energized as needed.

In the embodiment shown in FIG. 5, the drive-side coupling part 11 is formed by the coil holder 14 together with the actuator coil 15 and rotatably or positionally fixed to the motor shaft 7 is arranged. The driver profile 1, which is annular in the present case, is non-rotatably connected to the drive-side coupling part 1 1. In the present embodiment illustrated, the driver profile 1 is connected both to the output-side coupling part 12 and to the coil holder 14.

Furthermore, the output-side coupling part 12, the carrier of the complementary driver profile V is axially movable in the coupling direction KR. As can likewise be seen from FIG. 5, the spring element 10, which is elastically deflectable axially in the coupling direction KR, is fastened to an output-side flange 20 of the safety coupling 2. About this spring element 10, the output-side coupling member 12 is rotatably attached to the complementary driving profile V on the output-side flange 20. The output side flange 20 is in turn rotationally fixed to the transmission shaft 8 is arranged. The driven-side flange 20 and the transmission shaft 8 are rotatably supported in the housing 13.

As soon as the actuator coil 15 is energized via the slip rings 23 and the brush 24 in contact with the slip rings, an electromagnetic field is generated which causes the output side coupling part 12 acting as an armature to move axially from the position shown in FIG downwards. Thus, the safety clutch 2 is closed, that is, the mutually complementary driver profiles 1, V are in positive engagement with each other. The safety coupling 2 shown in FIG. 5 is designed such that when the actuator coil 15 is switched off, the safety coupling 2 is opened.

LIST OF REFERENCE NUMBERS

1, 1 'driver profile

2 safety coupling

4 tool

5 wall

6 electric drive motor

7 motor shaft

8 gear shaft

9 Drive-side flange of the safety coupling 10 Spring element

1 1 Drive-side coupling part

12 output side coupling part

13 housing

14 bobbin holders

15 actuator coil

20 Output side flange of the safety coupling

15 actuator coil

23 slip ring

24 brush

100 hand tool machine

EK Coupled condition

KR coupling direction

MF driver flank

NF trailing edge

R rotation direction

K wedge elements

Claims

claims

Hand tool (100), in particular hammer drill or combi hammer, with a safety coupling (2) via the torque transmission between a motor shaft (7) and a gear shaft (8) of the power tool (100) can be manufactured and interrupted, wherein the safety coupling a drive-side coupling part ( 1 1) and a driven-side coupling part (12) and can be actuated via a clutch actuator,

characterized in that on the drive-side coupling part (1 1) and on the output side coupling part (12) mutually complementary driver profiles (1, 1 ') are arranged, in particular in the manner of a crown gear, via which the drive-side coupling part (1 1) and the output side coupling part ( 12) can be coupled frictionally / positively.

Hand tool (100) according to claim 1,

characterized in that the Mitnehmerprofile (1, 1 ') are annular and axially to the coupling direction (KR) projecting wedge elements (K).

Hand tool (100) according to claim 2,

characterized in that the wedge elements (K) are formed asymmetrically.

Hand tool (100) according to one of the preceding claims,

characterized in that the drive-side coupling part (11) via an axially in the coupling direction (KR) elastically deflectable spring element (10) on a drive-side flange (9) of the safety coupling (2) is fixed, wherein the drive-side flange (9) preferably rotatably with the Motor shaft (7) is connected.

Hand tool (100) according to one of claims 1 to 3,

characterized in that the output-side coupling part (12) via an axially in the coupling direction (KR) elastically deflectable spring element (10) on a driven-side flange (20) of the safety coupling (2) is fixed, wherein the output-side flange (20) preferably rotatably with the Transmission shaft (8) is connected.

5. Hand tool (100) according to claim 4 or 5,

characterized in that the spring element (10) is installed biased so that the mutually complementary driver profiles (1, 1 ') are spaced from each other in unconfirmed Kupplungsaktuator.

Hand tool (100) according to one of the preceding claims,

characterized in that a drive-side coupling part (1 1) is mounted axially movable to the coupling direction (KR) or the output side coupling part (12) axially movable to the coupling direction (KR) is mounted.

8. Hand tool (100) according to one of the preceding claims,

characterized in that the motor shaft (7) and the transmission shaft (8) are arranged coaxially with each other. 9. Hand tool (100) according to one of the preceding claims,

characterized in that the clutch actuator is an electromagnetic actuator with an actuator coil (15) which is designed and arranged to act as an armature acting drive side coupling part (1 1) or acting as an anchor output side coupling part (12) without contact.

10. Hand tool (100) according to one of the preceding claims,

characterized in that the safety coupling (2) is opened when normally switched actuator coil. 1 1. Hand tool (100) according to one of the preceding claims,

characterized in that the actuator coil (15) is arranged fixed to the frame to a housing (13) of the power tool (100).

12. Hand tool (100) according to one of the preceding claims,

characterized in that the actuator coil (15) rotationally fixed to the motor shaft (7) is arranged and via a sliding contact, which is preferably realized via at least one slip ring (23) and at least one brush (24), can be supplied with a control current. Hand tool (100) according to one of the preceding claims,

characterized by an electronic unit for detecting a sudden deflection of the power tool (100), wherein the electronic unit is designed and arranged to switch the actuator coil (15) de-energized when a sudden deflection of the power tool (100) is detected.