Adaptable motor fan

Abstract

The invention relates to a power tool containing a first electric motor, a first shaft, a transmission device, a tool holder, a control device, a power supply and a rotatably mounted fan. The power tool contains a drive device which can be connected to the fan in such a way that the fan can be driven at at least a first and a second rotational velocity, the drive device being designed in such a way that selectively either the rotational velocity of the fan corresponds to a rotational velocity of the electric motor or the rotational velocity of the fan is higher or lower than a rotational velocity of the electric motor. The invention also relates to a method for the open-loop and closed-loop control of a power tool containing a first electric motor, a shaft, a transmission device, a tool holder, a control device, a power supply, a storage unit and a fan which can be driven by a drive device. The method comprises the following method steps: - capturing at least one temperature value; - comparing the temperature value with a temperature threshold value; and - adjusting the drive device from a first rotational speed value to a second rotational speed value if the temperature value corresponds to the temperature threshold value.

Description

[0001] Adaptable motor fan

[0002] The present invention relates to a machine tool comprising a first electric motor, a first shaft, a gear device, a tool holder, a control device, a power supply and a rotatably mounted fan for generating a cooling current.

[0003] Furthermore, the present invention relates to a method for controlling and regulating a machine tool, comprising a first electric motor, a first shaft, a gear device, a tool holder, a control device, a power supply, a storage unit and a fan driven by a drive device for generating a cooling current.

[0004] Electric motors used to drive machine tools can get very hot under certain circumstances. To regulate the temperature of the electric motor, fans are usually used to generate a cooling airflow.

[0005] However, the fans known from the prior art are designed in such a way that, especially at higher motor speeds, an airflow is generated that cannot provide sufficient cooling for the electric motor.

[0006] The object of the present invention is therefore to solve the problem described above.

[0007] The problem is solved by the subject matter of independent claims 1 and 5. Further advantageous embodiments of the subject matter according to the invention are contained in the corresponding dependent claims.

[0008] The task is solved in particular by a machine tool containing a first electric motor, a first shaft, a gear device, a tool holder, a control device, a power supply and a rotatably mounted fan for generating a cooling current.

[0009] According to the invention, a drive device is included which can be connected to the fan in such a way that the fan can be driven with at least a first and second rotational speed, wherein the drive device is designed such that optionally the rotational speed of the fan corresponds to a rotational speed of the first electric motor or the rotational speed of the fan is higher or lower than a rotational speed of the first electric motor.

[0010] According to an advantageous embodiment, the drive unit can be designed such that the fan can be driven in either a first or a second direction of rotation. This allows the airflow generated by the fan to flow through the machine tool in a first direction when the fan is operated in the first direction. Furthermore, the airflow generated by the fan can flow through the machine tool in a second direction when the fan is operated in the second direction. The first and second flow directions are opposite. These different flow directions can serve to expel dirt or contaminants from the machine tool housing.

[0011] According to an advantageous embodiment, the drive unit can be designed as a second electric motor. This allows the fan to continue operating even when the first electric motor is switched off, thus ensuring a cooling current is still generated for cooling the electric motor.

[0012] According to another advantageous embodiment, it may be possible for the drive device to be designed as a multi-stage transmission which can be reconnected to the first shaft.

[0013] According to another advantageous embodiment, it may be possible for the drive device to be releasably connected to the gearbox device via a torque transmission device.

[0014] The problem is further solved by a method for controlling and regulating a machine tool, comprising a first electric motor, a first shaft, a gear unit, a tool holder, a control device, a power supply, a storage unit and a fan driven by a drive device to generate a cooling current.

[0015] According to the invention, the following process steps are included.

[0016] - Recording at least one temperature value by at least one temperature sensor; - Comparing the at least one recorded temperature value with a temperature threshold stored in the memory unit, and

[0017] - Adjusting the drive unit from a first speed value to a second

[0018] Speed ​​value if at least one recorded temperature value corresponds to the temperature threshold.

[0019] The temperature sensor can be designed as a thermistor, NTC resistor or NTC thermistor (= Negative Temperature Coefficient Thermistor).

[0020] Further advantages will become apparent from the following description of the figures. The figures illustrate various embodiments of the present invention.

[0021] The figures, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider these features individually and combine them into meaningful further combinations.

[0022] They show:

[0023] Figure 1 shows a schematic side view of a machine tool according to a first embodiment;

[0024] Figure 2 shows a side view of a drive unit with a fan according to a first embodiment;

[0025] Figure 3 shows a side view of the drive unit with the fan according to a second embodiment, wherein the drive unit is set in a first position;

[0026] Figure 4 shows a side view of the drive unit with the fan according to the second embodiment, wherein the drive unit is set in a second position;

[0027] Figure 5 shows a side view of the drive unit with the fan according to the second embodiment, wherein the drive unit is set in a third position;

[0028] Figure 6 shows a schematic side view of the machine tool according to a second embodiment; and

[0029] Figure 7 shows a side view of the drive unit with the fan according to a third embodiment.

[0030] Examples of implementation:

[0031] Figure 1 shows a machine tool 1 according to a first embodiment.

[0032] The machine tool 1 shown in Figure 1 is designed in the form of a cordless screwdriver according to an exemplary embodiment.

[0033] According to an alternative embodiment, the machine tool 1 can also be designed in the form of a saw, a grinding device, a hammer drill or the like.

[0034] The power tool 1, designed as a cordless screwdriver, essentially comprises a housing 2, a handle s and a tool holder 4.

[0035] The housing 2 has a front end 2a, a rear end 2b, a top end 2c and a bottom end 2d.

[0036] The tool holder 4 is positioned at the front end 2a of the housing 2. The tool holder 4 serves to receive and hold a tool 4a. In the exemplary embodiment, the tool 7 is designed as a screwdriver bit.

[0037] A first end 3a of the handle 3 is positioned at the lower end 2d of the housing 2. An interface 6 is provided at the second end 3b of the handle 3.

[0038] As also shown in Figure 1, the handle 3 has an activation switch 8 with which the machine tool 1 can be set to an activation state or deactivation state.

[0039] The energy storage unit 5 can be reattached to interface 6 in a releasable manner.

[0040] In the present embodiment, the energy storage unit 5 is designed in the form of a single accumulator. Alternatively, more than one accumulator can also be provided as the energy storage unit 5 of the machine tool 1.

[0041] The energy storage unit 5 serves to supply the machine tool 1 with electrical energy.

[0042] Inside the housing 2, there is essentially an electric motor 9 as a drive, a gear unit 10, a first shaft 11, a storage unit 12, a temperature sensor 13, a fan 14 and a drive unit 15.

[0043] A control device 16 is located inside the handle 3. The control device 16 serves primarily to control and regulate the functions of the machine tool 1 and, in particular, the first electric motor. Among its functions is the adjustment of the speed of the electric motor 9. The electric motor 9, the gear unit 10, the first shaft 11, and the tool holder 4 are arranged inside the housing 2 in such a way that a torque generated in the electric motor 9 can be transmitted to the gear unit 10, the first shaft 11, and finally to the tool holder 4 or to the tool 7.

[0044] The electric motor 9 is designed in the form of a brushless DC motor.

[0045] The storage unit 12 serves to store and provide threshold values. These threshold values ​​include, among others, temperature thresholds and speed thresholds for the first electric motor 9. As shown in Figure 1, the storage unit 12 is a component of the control unit 16. According to an alternative embodiment of the machine tool 1, the storage unit 12 can also be designed as an independent component.

[0046] The temperature sensor 13 is used to detect temperature values ​​at the first electric motor 9. For this purpose, the temperature sensor 13 is positioned inside the first electric motor 9. The temperature sensor 13 is connected to the control unit 16 via lines L, so that the temperature values ​​detected by the temperature sensor 13 can be transmitted to the control unit 16. The temperature sensor 13 is designed as an NTC resistor.

[0047] According to an alternative embodiment of the machine tool 1, several different temperature sensors can also be positioned at different locations on the electric motor 9 to simultaneously detect several temperature values.

[0048] In the present embodiments, the fan 14 is designed as a fan and serves to generate a cooling flow KS. As can be seen in the figures, the fan 14 is arranged behind the first electric motor 9 in the direction of arrow A. When the fan 14 rotates about the axis of rotation R, a cooling flow KS is generated. The cooling flow KS is drawn into the housing 2 through front openings 17a and expelled from the housing 2 through rear openings 17b. The cooling flow KS flows between the two openings 17a and 17b over and through the first electric motor 9, thereby cooling it.

[0049] The drive unit 15 serves to drive (i.e. rotate) the fan 14 about the axis of rotation R.

[0050] Figure 2 shows the drive unit 15 in a first embodiment.

[0051] The drive unit 15 is designed as a second electric motor 18. The drive unit 15, designed as a second electric motor 18, is connected to the control unit 16 in such a way that the control unit 16 can set the direction of rotation DR1, DR2, and the rotational speed of the fan 14. In the first direction of rotation DR1, the fan 14 rotates in a first direction, and in the second direction of rotation DR2, the fan 14 rotates in a second direction. The first and second directions of rotation DR1, DR2 are opposite in direction.

[0052] Figures 3 to 5 show the drive unit 15 in a second embodiment.

[0053] The drive unit 15 is designed as a multi-stage transmission. In the present embodiment, the drive unit 15 is configured as a two-stage transmission, which can be set to neutral, first gear, or second gear. An electromechanical actuator 22 is connected to the drive unit 15 and to the control unit 16. The electromechanical actuator 22 is connected to the first shaft 11 and serves to adjust the drive unit 15, which is configured as a transmission. When the control unit 16 sends an electrical signal to the actuator 22 via a line L, the actuator 22 moves the first shaft 11 accordingly in direction A or B.

[0054] The actuator 22 can be designed in the form of an electric motor.

[0055] The transmission comprises a first small gear 19a, a second small gear 19b, a first large gear 19c, a second large gear 19d, a transmission gear 19e, a drive gear 19f, a second shaft 20, and a third shaft 21. The first small gear 19a and the first large gear 19c are non-rotatably connected to the first shaft 11. The second small gear 19b, the second large gear 19d, and the transmission gear 19e are non-rotatably connected to the second shaft 20. The drive gear 19f is connected to the third shaft 21. The transmission gear 19e and the drive gear 19f mesh with each other, allowing torque to be transmitted between them. The drive gear 19f is non-rotatably connected to the fan 14.

[0056] The drive unit 15, designed as a gearbox, is connected to the shaft of the first electric motor 9, so that a torque generated by the first electric motor 9 can be transmitted to the gearbox.

[0057] In Figure 3, the drive unit 15, designed as a two-stage gearbox, is set to an idle mode by the actuator 22. In idle mode, the first small gear 19a, the second small gear 19b, the first large gear 19c, and the second large gear 19d are not engaged. When the drive unit 15 is in idle mode, the fan 14 does not rotate about the axis of rotation R, and therefore no airflow KS occurs.

[0058] Figure 4 shows the drive unit 15, designed as a gearbox, in first gear. Here, the first small gear 19a is connected to the second large gear 19d, so that the fan 14 rotates more slowly than the first shaft 11. To engage the drive unit 15 from neutral to first gear, the first shaft 11 is pushed in the direction of A by the actuator 22. When the gearbox 25 is in first gear, a correspondingly small airflow KS is generated.

[0059] Figure 5 shows the drive unit 15, designed as a gearbox, in second gear. Here, the first large gear 19c is connected to the second small gear 19b, causing the fan to rotate faster than the first shaft 11. To shift the drive unit 15 from neutral or from first gear to second gear, the first shaft 11 is pushed in the direction of B by the actuator 22. When the gearbox 29 is in second gear, a correspondingly larger airflow KS is generated than when the gearbox 29 is in first gear.

[0060] Figures 6 and 7 show the drive unit 15 in a third embodiment.

[0061] The drive unit 15 essentially comprises a gearbox 29 and a transmission mechanism.

[0062] The gearbox 29 is designed as a two-stage gearbox, which can be set to neutral, first gear or second gear.

[0063] An electromechanical actuator 22 is connected to the drive unit 15 and to the control unit 16. The electromechanical actuator 22 is connected to the first shaft 11 and serves to adjust the gearbox 29. When the control unit 16 sends an electrical signal to the actuator 22 via a line L, the actuator 22 moves the first shaft 11 accordingly in direction A or B.

[0064] The gearbox 29 comprises a first small gear 19a, a second small gear 19b, a first large gear 19c, a second large gear 19d, a transmission gear 19e, a drive gear 19f, a second shaft 20, and a third shaft 21. The first small gear 19a and the first large gear 19c are non-rotatably connected to the first shaft 11. The second small gear 19b, the second large gear 19d, and the transmission gear 19e are non-rotatably connected to the second shaft 20.

[0065] The drive gear 19f is non-rotatably connected to the third shaft 21.

[0066] The transmission gear 19e and the drive gear 19f are connected to each other via a first chain 24, so that a torque can be transmitted between the transmission gear 19e and the drive gear 19f and the third shaft 21. The drive gear 19f is positioned at one end of the third shaft 21. At the other end, a gear 25 is fixed to the shaft 21. The fan 14 is fixed to a fourth shaft 26. The fourth shaft 26 is mounted on the housing 2 of the machine tool 1. Another gear 27 is fixed to the fourth shaft 26. Gear 25 is connected to the second gear 27 via a second chain 28, so that a torque can be transmitted from the third shaft 21, or from gear 25, to the second gear 27. By transmitting the torque to the second gear 27, the fan 14 is driven.

[0067] In Figure 7, the gearbox 29 is set to neutral.

[0068] In idle mode, the first small gear 19a, the second small gear 19b, the first large gear 19c, and the second large gear 19d are not connected to each other. When the drive unit 15 is in idle mode, the fan 14 does not rotate about the axis of rotation R, resulting in no airflow KS.

[0069] When the gearbox 29 is in first gear, the first small gear 19a is connected to the second large gear 19d, causing the fan to rotate more slowly than the first shaft 11. To engage the gearbox 29 from neutral to first gear, the first shaft 11 is pushed towards A by the actuator 22. When the gearbox 29 is in first gear, a correspondingly small airflow KS is generated.

[0070] When the gearbox 29 is set in second gear, the first large gear 19c is connected to the second small gear 19b, so that the fan rotates faster than the first shaft 11. To move the gearbox 29 from neutral or from first gear to second gear, the first shaft 11 is pushed towards B by the actuator 22.

[0071] When the gearbox 29 is in second gear, a correspondingly larger airflow KS is generated than when the gearbox 29 is in first gear.

[0072] As mentioned above, the temperature sensor 13 is connected to the control unit 16 such that the temperature values ​​detected by the temperature sensor 13 are sent to the control unit 16. When the temperature sensor 13 detects a temperature value that corresponds to a threshold value stored in the memory unit 12, a corresponding signal is sent from the control unit 16 to the drive unit 15. Reaching the temperature threshold corresponds to an excessively high temperature of the electric motor 9. The signal causes the drive unit 15 to adjust the fan 14 to rotate faster in order to generate a greater airflow KS for cooling the electric motor 9.

[0073] 1 machine tool

[0074] 2 cases

[0075] 3 handle

[0076] 3a first end of the handle

[0077] 3b second end of the handle

[0078] 4 Tool holder

[0079] 5 Energy supply

[0080] 6. Machine tool interface

[0081] 7 tools

[0082] 8 activation switches

[0083] 9 Electric motor

[0084] 10 Gearbox device

[0085] 11 first wave

[0086] 12 storage units

[0087] 13 Temperature sensor

[0088] 14 fans

[0089] 15 Drive unit

[0090] 16 Control unit

[0091] 17a front openings of the housing

[0092] 17b rear openings of the case

[0093] 18 second electric motor

[0094] 19a first small gear

[0095] 19b second small gear

[0096] 19c first large gear

[0097] 19d second large gear

[0098] 19e Transmission gear 19f Drive gear

[0099] 20 second wave

[0100] 21 third wave

[0101] 22 Actuator 24 First chain

[0102] 25 gear

[0103] 26 fourth wave

[0104] 27 more gear

[0105] 28 second chain 29 manual transmission

[0106] DR1 first direction of rotation

[0107] DR2 second direction of rotation

[0108] L line KS airflow

[0109] R axis of rotation

Claims

Patent claims 1. Machine tool (1) comprising a first electric motor (9), a first shaft (11), a gear unit (10), a tool holder (4), a control unit (16), a power supply (5) and a rotatably mounted fan (14) for generating a cooling current (KS), characterized in that a drive unit (15) is included which can be connected to the fan (14) in such a way that the fan (14) can be driven with at least a first and second rotational speed, wherein the drive unit (15) is designed such that optionally the rotational speed of the fan (14) corresponds to a rotational speed of the first electric motor (9) or the rotational speed of the fan (14) is higher or lower than a rotational speed of the first electric motor (9).

2. Machine tool (1) according to claim 1 , characterized in that the drive device (15) is designed such that the fan (14) can be driven either in a first direction of rotation (DR1) or in a second direction of rotation (DR2).

3. Machine tool (1) according to claim 1 or 2, characterized in that the drive device (15) is designed as a second electric motor (18).

4. Machine tool (1) according to claim 1 or 2, characterized in that the drive device (15) is designed as a multi-stage transmission which can be reconnected to the first shaft (11).

5. Machine tool (1) according to claim 1 or 2, characterized in that the drive device (15) can be releasably connected to the gear device (10) via a torque transmission device.

6. Method for controlling and regulating a machine tool (1), comprising a first electric motor (9), a shaft (11), a gear unit (10), a tool holder (4), a control device (16), a power supply (5), a storage unit (12) and a fan (14) driven by a drive unit (15) for generating a cooling current (KS), characterized by the method steps - Recording at least one temperature value by at least one Temperature sensor (13); - Comparison of at least one recorded temperature value with a temperature threshold stored in the storage unit (12), and - Adjusting the drive unit (15) from a first speed value to a second speed value when at least one detected temperature value corresponds to the temperature threshold.

Images