EP3421183B1 - Electromechanical gear selection device with a geneva gear - Google Patents

Description

The present invention relates to a method for setting a gear in a gearbox of a machine tool, in particular a core drilling machine, the machine tool containing an electric motor for generating and transmitting a torque to the gearbox and a control device for setting the speed of the electric motor and the gearbox having an operating device for Selecting a gear in the gearbox, a shift fork for engaging a gear in the gearbox and a Geneva cross gear for transmitting a movement of the operating device to the shift fork, the operating device containing at least one signal transmitter and at least one sensor for receiving at least one signal from the at least one signal transmitter .

The invention also relates to a machine tool for carrying out the method according to the invention. The invention also relates to a transmission for a machine tool, in particular a core drilling machine, for carrying out the method according to the invention.

For machine tools, in particular machine tools with a rotating tool, it is of great importance that the rotational speed of the tool is precisely matched to the tool used.

The size, volume and weight of the tool used are particularly important factors here. If the rotation speed is too low with a tool that is too large, the work progress is too slow and inefficient, so that the work process as a whole is prolonged. In contrast, too high a rotational speed can lead to damage to the machine tool or the tool.

In core drilling machines, the precise adjustment or adaptation of the rotational speed of the tool, i.e. the drill bit, to the size of the drill bit or the diameter of the drill bit is of particular importance.

Core drilling machines use cylindrical drill bits which, with the aid of a diamond-coated cutting edge, can cut holes in mineral materials, such as concrete or masonry. In order to be able to vary the speed and torque of the drill bit for different applications, core drilling machines usually have also via a transmission that contains at least two gears. With the help of the different gears, the rotational speed and the torque of the drill bit can be adjusted. Maintaining a circumferential speed of the drill bit that is as constant as possible during the core drilling process is of great importance for the proper and efficient sequence of the core drilling process and, in particular, for using the drill bit and the core drilling machine in a manner that is gentle on the material. However, this often requires a relatively fine adjustment of the device to the respective drill bit diameter. The correct coordination of the rotational speed, the torque and the correct gear to the diameter of the respective drill bit used with a constantly changing nature (e.g. degree of hardness) of the material to be machined, however, often poses major problems for a user of the core drilling machine. The core drilling process can either become inefficient and slow, or the drill bit can be damaged.

With the core drilling machines on the market or with the core drilling machines according to the prior art, however, such fine adjustment between the size (diameter), the rotational speed, the torque of the drill bit or the selected gear of the core drill is either not provided at all or for the user the core drilling machine realized very laboriously.

For example disclosed EP 2 762 278 A2 an electric tool known from the prior art. The US 2013/292147 A1 describes an electric tool with a speed selector switch. In the EP 3 135 438 A1 an electrically operated tool is described which includes a speed control circuit. The US 2013/126201 A1 discloses a transmission for a power tool with variable speed, wherein the power can be transmitted with a constant or a variable gear set.

The object of the present invention is to solve the above-mentioned problem.

The object is achieved by the subject matter of independent claims 1, 2 and 5. Advantageous embodiments of the subject matter according to the invention are contained in the dependent claims.

The object is achieved by providing a method for setting a gear in a gearbox of a machine tool, in particular a core drilling machine, the machine tool containing an electric motor for generating and transmitting a torque to the gearbox and a control device for setting the speed of the electric motor and that Transmission, an operating device for selecting a gear in the transmission, a shift fork for engaging a gear in the transmission and a Maltese cross gear for transmitting a movement of the operating device to the Contains shift fork, the operating device containing at least one signal transmitter and at least one sensor for receiving at least one signal from the at least one signal transmitter.

The object is also achieved by providing a machine tool for carrying out the method according to the invention and a transmission for a machine tool, in particular a core drilling machine, for carrying out the method according to the invention.

• Einstellen der Bedienvorrichtung von einer ersten Position in eine zweite Position zum Auswählen eines Ganges in dem Getriebe;
• Erfassen eines Signals durch den wenigstens einen Sensor entsprechend der zweiten Position der Bedienvorrichtung;
• Senden des Signals an das Steuerungsgerät;
• Einstellen der Drehzahl des Elektromotors von einem ersten Wert auf einen zweiten Wert durch das Steuerungsgerät;
• Positionieren der Bedienvorrichtung von der zweiten Position in eine dritte Position;
• Einstellen des Malteserkreuzgetriebes von einer ersten Position in eine zweite Position entsprechend der dritten Position der Bedienvorrichtung; und
• Einstellen der Schaltgabel von einer ersten Position in eine zweite Position zum Wechseln von einem ersten Gang in einen zweiten Gang.

According to the invention it is provided that the method contains the following method steps:

• Adjusting the operating device from a first position to a second position for selecting a gear in the transmission;
• Detecting a signal by the at least one sensor corresponding to the second position of the operating device;
• Sending the signal to the control device;
• Adjusting the speed of the electric motor from a first value to a second value by the control device;
• Positioning the operating device from the second position to a third position;
• Adjusting the Geneva drive from a first position to a second position corresponding to the third position of the operating device; and
• Adjusting the shift fork from a first position to a second position for changing from a first gear to a second gear.

Furthermore, the object is achieved by providing a machine tool for carrying out the method according to the invention, the machine tool having a transmission, an electric motor for generating and transmitting a torque to the transmission, a control device for setting the speed of the electric motor, an operating device for selecting a gear in the transmission, a shift fork for engaging a gear in the transmission and a Maltese cross gear for transmitting a movement of the operating device for selecting a gear in the transmission to the shift fork, the operating device having at least one signal transmitter and at least one sensor for receiving at least one signal of the at least contains a signal transmitter.

According to an advantageous embodiment of the present invention, it may be possible that the signal transmitter in the form of a magnet and the sensor in the form of a Hall sensor is designed. However, it is also possible that any other suitable type of signal transmitter and sensor is used.

According to an advantageous embodiment of the present invention, it may be possible that a shift energy store is contained in the transmission, whereby a force can be exerted on a shift fork of the transmission in order to preload the shift fork for a transition from a first position to a second position. The switch energy store can be designed as a spring element. In this way, a new gear can be preselected during a gear selection process, so that the new gear is set as soon as the transmission is able to do so. This is particularly advantageous if the constellation of the gear wheels within the transmission does not allow a new gear to be set immediately.

In addition, the object is achieved by providing a gear for a machine tool, in particular a core drilling machine, for carrying out the method according to the invention, an electric motor in the machine tool generating a torque and transmitting it to the gear, a gear in the gear being selectable with an operating device is. It is provided that the transmission comprises a shift fork for engaging a gear in the transmission, as well as a Maltese cross gear for transmitting a movement of the operating device to the shift fork.

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.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Werkzeugmaschine mit einem erfindungsmäßen Getriebe, einem Elektromotor, einem Steuerungsgerät und einer Bedienvorrichtung;

Fig. 2

eine Detailansicht eines Drehschalters der Bedienvorrichtung mit einem Signalgeber und Sensor;

Fig. 3

eine perspektivische Ansicht eines erfindungsgemäßen Getriebes der Werkzeugmaschine;

Fig. 4

eine perspektivische Ansicht der Bedienvorrichtung, einer Schaltgabel und Zahnräder;

Fig. 5

eine weitere perspektivische Ansicht der Bedienvorrichtung, der Schaltgabel und Zahnräder;

Fig. 6

eine Vorderansicht der Bedienvorrichtung, der Schaltgabel und Zahnräder;

Fig. 7

eine Schnittansicht durch die Bedienvorrichtung;

Fig. 8

den Drehschalter der Bedienvorrichtung, welcher von einer ersten Stellung in eine zweite Stellung bewegt wird; und

Fig. 9

den Drehschalter der Bedienvorrichtung, welcher von einer zweiten Stellung in eine dritte Stellung bewegt wird.

In the figures, the same and similar components are numbered with the same reference numerals. Show it:

Fig. 1

a schematic representation of a machine tool according to the invention with a transmission according to the invention, an electric motor, a control device and an operating device;

Fig. 2

a detailed view of a rotary switch of the operating device with a signal transmitter and sensor;

Fig. 3

a perspective view of a transmission of the machine tool according to the invention;

Fig. 4

a perspective view of the operating device, a shift fork and gears;

Fig. 5

a further perspective view of the operating device, the shift fork and gears;

Fig. 6

a front view of the operating device, the shift fork and gears;

Fig. 7

a sectional view through the operating device;

Fig. 8

the rotary switch of the operating device, which is moved from a first position to a second position; and

Fig. 9

the rotary switch of the operating device, which is moved from a second position to a third position.

Embodiment:

Fig. 1 shows an embodiment of a machine tool 1 according to the invention in an embodiment of a core drilling machine.

The machine tool 1 designed as a core drilling machine essentially contains a housing 2, an electric motor 3, a gear 4, a control device 18, an output shaft 6, an operating device 7 and a tool holder 8. How Fig. 1 As can be seen, the electric motor 3, the transmission 4, the control device 18 and the output shaft 6 are positioned in the interior of the housing 2. The operating device 7 is positioned on the housing 2 so that it can be operated from the outside by a user. A power cable 9 for supplying the machine tool 1 with electrical power is indicated on the housing 2.

The electric motor 3 is used to generate a torque which is passed on to the tool holder 8 via the output shaft 6 and the transmission 4. The tool holder 8 is used to receive and hold a tool with which a material (e.g. concrete) can be processed. In the case of the configuration of the machine tool 1 in the form of a core drilling machine, the tool can be a drill bit. Neither the tool nor the material are shown in the figures.

The control device 18 is used, among other things, to set and monitor the speed of the electric motor 3. For this purpose, the control device 18 is connected to the operating device 7, the transmission 4 and the electric motor 3, cf. Fig. 1 .

The transmission 4 contains three gears 10 for the variable translation of the torque introduced by the electric motor 3 into the transmission 4. Although the transmission 4 shown in the figures contains only three gears 10, it is possible to insert more than three gears in the transmission 4 as follows shown in detail. However, it is also possible for the transmission 4 to contain more or fewer than three gearwheels 10.

In the Figures 3 to 6 an embodiment of the transmission 4 according to the invention is shown. The gear 4 is connected to the operating device 7 and essentially contains a housing 11, part of the output shaft 6, a step gear 12, three gears 10 and a shift fork 13. The step gear 12 and a part of the shift fork 13 are in the housing 11 positioned.

The operating device 7 is used by the user of the machine tool 1 to select a gear in the transmission 4 or to set a speed value for the electric motor 3. The setting of the speed value with the aid of the operating device 7 according to the present inventive method does not cause a mechanical, but an electronic gear change. In other words: the setting or changing of the speed value with the aid of the operating device 7 appears as a mechanical gear change, in which a change is made from one number wheel constellation to another gear wheel constellation.

The operating device 7 also contains a rotary switch 14 which can be rotated in the direction of rotation C or D relative to a numeric display. The user of the core drilling machine 1 recognizes which gear is engaged or which gear can be engaged by the numeric display. The rotary switch 14 can also be referred to as a gear selector switch.

According to an alternative embodiment not shown in the figures, the operating device 7 can also be connected to an electronic display in order to show the user the currently engaged gear by means of a screen (display).

The Maltese cross gear is a specific embodiment of a step gear 12 and essentially serves to transfer the rotary movement of the rotary switch 14 in the direction of rotation C or D into a linear movement of the shift fork 13 in direction A or B. The step gear 12, designed as a Geneva gear, is therefore connected to the shift fork 13 . The special feature of the Geneva drive 13 is that not every rotary movement of the rotary switch 14 results in a corresponding rotation of the Geneva drive 12. In other words: only every second rotary movement performed in sections or only every second rotary movement along a sector leads to a rotary movement of the Geneva gear mechanism 12.

The shift fork 13 in turn serves to actually align the gears 10 to one another within the transmission 4 in order to set a specific gear ratio or gear configuration.

The operating device 7 also contains a signal transmitter 15 in the form of a magnet. Alternatively, the setting device can also contain more than one signal transmitter 15 in the form of several magnets. However, it is also possible for any other suitable type of signal transmitter 15 to be used. For example, according to an alternative embodiment, a metal ring can also be provided as a signal transmitter 15 and an induction sensor that matches the metal ring.

The signal transmitter 15 is firmly positioned on the rotary switch 14 and is used to transmit signals corresponding to the position or rotary position of the rotary switch 14 of the operating device 7.

In addition, the operating device 7 contains a number of sensors 16 in the form of Hall sensors corresponding to the configuration of the signal transmitter 15 as a magnet. However, it is also possible that any other suitable type of sensor 16 is used. The sensor 16 is used to receive the signal from the signal generator 15. The in Figure 2 Arrows shown on the signal generator 15 represent magnetic springs.

As in Fig. 2 shown, four sensors 16 are firmly positioned in a circle on the operating device 7 in order to detect the magnetic field of the signal transmitter 15 configured as a magnet on the rotary switch 14. It should be noted that a sensor 16 is only provided at every second possible rotary position of the rotary switch 14 (cf. Fig. 8 and 9 ). If the rotary switch 14 is aligned with one of these four rotary positions equipped with sensor 16, the sensor 16 can recognize the signal transmitter 15 on the rotary switch 14 and assign the position of the rotary switch 14 to one of the four rotary positions. However, it is also possible for sensors 16 to be positioned at more or less than four rotational positions.

Each sensor 16 is connected to a control unit 5 via a line 17 in order to send the received signals from the signal generator to the control unit 5 (cf. Fig. 2 , 8th and 9 ). The control unit 5 is in turn connected to a control device 18 of the electric motor 3 (cf. Fig. 1 ). Alternatively, the control unit 5 is also connected directly to the electric motor 3. The connection is used to send a corresponding signal from the control unit 5 of the transmission 4 to the control device 18 of the electric motor 3. The control device 18 can regulate the power supply to the electric motor 3 and thus control the speed value of the electric motor 3. The speed value is the target speed value.

Because (as already described above) the Maltese cross gear 12 can convert a continuous rotary movement of the rotary switch 14 into an intermittent rotary movement, not every rotary movement of the rotary switch 14 leads to an activation of the shift fork 13 and consequently to a mechanical gear change or to a change in the Gear constellation.

If, as in Fig. 8 shown, the rotary switch 14 is rotated from a first position to a second position in direction C in order to move the operating device 7 from a first position to a second position for selecting a gear in the transmission 4, with the help of the Geneva gear 12, the shift fork 13 is moved in direction A, so that the gears 10 in the transmission 4 are brought into a different constellation. In other words: a higher gear is engaged by the Geneva cross gear 12 and the shift fork 13. In this case, no signal is sent from the sensor 16 via the control unit 5 to the Control device 18 sent in order to change the speed of the electric motor 3. The gear change takes place purely mechanically.

However, if, as in Fig. 9 As shown, the rotary switch 14 is further rotated from the second position to a third position in direction C in order to move the operating device 7 from the second position to a third position for selecting a different gear in the transmission 4, a signal from the signal transmitter 15 (ie by the magnet) detected at the corresponding sensor 16. The sensor 16 sends a signal to the control unit 5. The control unit 5 detects the rotary position of the rotary switch 14 and in turn sends a corresponding signal via the control device 18 to the electric motor 3 in order to set a speed setpoint. In the present case, the speed setpoint is increased. The shift fork 13 is not activated by the Geneva cross gear 12, so that a purely electronic gear change is carried out. By changing the speed setpoint of the electric motor 3, an additional spread for the transmission 4 can therefore be achieved without a mechanical gear change, ie without a new number wheel constellation.

According to an alternative embodiment, a shift energy store can also be contained in the transmission 4. The switch energy store can be designed as a spring mechanism or spring. The switching energy store, which is designed as a spring mechanism, exerts a force on the switching fork 13 in order to preload the switching fork 13 for a transition from a first position to a second position. The switch energy store is not shown in the figures.

If the linear movement of the shift fork 13 is not possible, the shift energy store designed as a spring mechanism is activated, which stores the kinetic energy in a preload or spring preload, so that a gear preselection is available. This means that the selected gear can only be implemented when restarting or at a low speed. As soon as the shift fork 13 can move, the gear preselected by the shift energy store is engaged by means of the shift fork 13 and the shift energy store takes up the starting position again, ie, the non-tensioned position. The gear preselection mechanism is designed in such a way that it is possible to shift from the first to the highest selectable gear without creating an alignment within the shift mechanism.

Reference number:

1

Machine tool

2

Machine tool housing

3

Electric motor

4th

transmission

5

Control unit

6th

Output shaft

7th

Control device

8th

Tool holder

9

Power cord

10

Gears

11

Housing of the gearbox

12th

Step gear in the form of a Maltese cross gear

13th

Shift fork

14th

Rotary switch

15th

Signaling device

16

sensor

17th

management

18th

Control device

Claims (5)

1. Method for setting a gear in a gear mechanism (4) of a power tool (1), in particular a power core drill, wherein the power tool (1) includes an electric motor (3) for generating and transmitting a torque to the gear mechanism (4) and a control unit (18) for setting the speed of the electric motor (3), and the gear mechanism (4) includes an operating device (7) for selecting a gear in the gear mechanism (4), a gearshift fork (13) for engaging a gear in the gear mechanism (4) and a Geneva gear mechanism (12) for transmitting a movement of the operating device (7) to the gearshift fork (13), wherein the operating device (7) includes at least one signal transmitter (15) and at least one sensor (16) for receiving at least one signal from the at least one signal transmitter (15), characterized by the method steps of

   - setting the operating device from a first position into a second position for selecting a gear in the gear mechanism (4);

   - detecting a signal by the at least one sensor (16) in accordance with the second position of the operating device (7);

   - sending the signal to the control unit (18);

   - setting the speed of the electric motor (3) from a first value to a second value by the control unit (18);

   - positioning the operating device (7) from the second position into a third position;

   - setting the Geneva gear mechanism (12) from a first position into a second position in accordance with the third position of the operating device (7); and

   - setting the gearshift fork (13) from a first position into a second position for changing from a first gear to a second gear.
2. Power tool (1) for carrying out the method according to Claim 1, including a gear mechanism (4), an electric motor (3) for generating and transmitting a torque to the gear mechanism (4), a control unit (18) for setting the speed of the electric motor (3), an operating device (7) for selecting a gear in the gear mechanism (4), a gearshift fork (13) for engaging a gear in the gear mechanism (4) and a Geneva gear mechanism (12) for transmitting a movement of the operating device (7) for selecting a gear in the gear mechanism (4) to the gearshift fork (13), wherein the operating device (7) includes at least one signal transmitter (15) and at least one sensor (16) for receiving at least one signal from the at least one signal transmitter (15).
3. Power tool (1) according to Claim 2,
   characterized in that the signal transmitter (15) is designed in the form of a magnet and the sensor (16) is designed in the form of a Hall sensor.
4. Power tool (1) according to Claim 2 or 3,
   characterized in that the gear mechanism (4) includes a shifting energy store, whereby a force can be exerted on a gearshift fork (13) of the gear mechanism (4) in order to pretension the gearshift fork (13) for a transfer from a first position to a second position.
5. Gear mechanism (4) for a power tool (1), in particular a power core drill, for carrying out the method according to Claim 1, wherein an electric motor (2) in the power tool (1) generates a torque and transmits it to the gear mechanism (4), wherein a gear can be selected in the gear mechanism (4) with an operating device (7), wherein the gear mechanism (4) comprises a gearshift fork (13) for engaging a gear in the gear mechanism (4), and a Geneva gear mechanism (12) for transmitting a movement of the operating device (7) to the gearshift fork (13).

Images