Power tool with electromechanical speed switch

Abstract

A power tool includes a housing, a motor mounted in the housing, a gearbox operatively connected to the motor, the gearbox switchable between a low speed, high torque operating mode and a high speed, low torque operating mode, a spindle configured to receive torque from the motor through the gearbox, a speed switch having a movable selector switch for switching the gearbox between the low speed, high torque operating mode and the high speed, low torque operating mode, a shaft movable in response to movement of the selector switch, a magnet connected to the shaft, and a controller configured to vary an operating speed of the motor based on a detected position of the magnet.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 683,123, filed August 14, 2024, and U.S. Provisional Patent Application No. 63 / 623,066, filed January 19, 2024, the entire contents of which are incorporated herein by reference. Area of Revelation

[0002] The present disclosure relates to a power tool, in particular to a core drill. Background of the Revelation

[0003] Core drills are typically used to remove a cylinder of material from a workpiece. Overview of Revelation

[0004] In some aspects, the techniques described herein relate to a power tool comprising: a housing; a motor mounted in the housing; a transmission operatively connected to the motor, the transmission switchable between a low speed, high torque mode of operation and a high speed, low torque mode of operation; a spindle configured to receive torque from the motor through the transmission; a speed switch having a movable selector to switch the transmission between the low speed, high torque mode of operation and the high speed, low torque mode of operation, a shaft movable in response to movement of the selector, and a magnet connected to the shaft;and a controller configured to change an operating speed of the motor based on a determined position of the magnet.;

[0005] In some aspects, the techniques described herein relate to a power tool comprising: a housing; a motor mounted in the housing; a gear housing supported in the housing; a gearbox disposed in the gearbox and operatively connected to the motor, the gearbox switchable between the low speed, high torque mode of operation and a high speed, low torque mode of operation; a spindle configured to receive torque from the motor through the gearbox; a movable selector switch for switching the gearbox between the low speed, high torque mode of operation and the high speed, low torque mode of operation; a cam connected to and movable with the selector switch; a shaft configured to be axially displaced v by movement of the cam;and a controller configured to vary an operating speed of the motor in response to the displacement of the shaft, wherein the cam and the shaft are disposed between the housing and the transmission housing;

[0006] In some aspects, the techniques described herein relate to a power tool comprising: a housing; a motor mounted in the housing; a gearbox operatively connected to the motor, the gearbox having a first gear, a second gear, and a shift ring configured to engage one of the first gear and the second gear; a spindle configured to receive torque from the motor through the gearbox; a rotatable shift ring to move the shift ring to engage one of the first gear and the second gear; a shaft configured to be axially translated by rotation of the shift ring; and a sensor assembly configured to determine a position of a magnet carried by the shaft to electronically change an operating speed of the motor.

[0007] Further features and aspects of the present disclosure will become apparent upon consideration of the following detailed description and the accompanying drawings. Brief description of the drawings Fig. 1 is a perspective view of a core drill according to an embodiment of the disclosure, with a tool bit connected to the core drill. Fig. 2 is another perspective view of the core drill from Fig. 1 without using the tool. Fig. 3 is a cross-sectional view of the core drill of Fig. 1, which runs along line 3-3 in Fig. 1 is shown. Fig. 4 is a plan view of the core drill from Fig. 1 with an electromechanical speed switch according to an embodiment of the disclosure, wherein the electromechanical speed switch is arranged in a first position. Fig. 5 is an enlarged side view of the core drill of Fig. 1, wherein the electromechanical speed switch consists of Fig. 4 has an operating button in the first position. Fig. 6 is a cross-sectional view of the electromechanical speed switch of Fig. 4 with parts removed. Fig. 7 is an enlarged side view of the core drill of Fig. 1, where the operating button is made of Fig. 5 is arranged in a second position. Fig. 8 is a plan view of the core drill from Fig. 1, wherein the electromechanical speed switch consists of Fig. 4 is in the second position. Fig. 9 is a cross-sectional view of the electromechanical speed switch of Fig. 8 with parts removed. Fig. 10 is an enlarged side view of the core drill of Fig. 1, where the operating button is made of Fig. 5 is arranged in a third position. Fig. 11 is a plan view of the core drill from Fig. 1, wherein the electromechanical speed switch consists of Fig. 4 is in the third position. Fig. 12 is a cross-sectional view of the electromechanical speed switch of Fig. 11 with parts removed. Fig. 13 is an enlarged view of the core drill from Fig. 1, where the operating button is made of Fig. 5 is arranged in a fourth position. Fig. 14 is a plan view of the core drill from Fig. 1, wherein the electromechanical speed switch consists of Fig. 4 is in the fourth position. Fig. 15 is a cross-sectional view of the electromechanical speed switch of Fig. 14 with parts removed. Fig. 16 is a cross-sectional view of an electromechanical speed switch according to another embodiment of the disclosure. Fig. Figure 17 is a diagram showing the changes in magnetic flux at different linear travels of a shaft of the electromechanical speed switch of Fig. 4 explained. Fig. Figure 18 is a graphical representation of the magnetic flux of a magnet of the electromechanical speed switch of Fig. 4. Fig. 19 is a perspective view of a core drill with parts removed, the core drill including an electromechanical speed switch according to another embodiment of the disclosure. Fig. 20 is a plan view of the core drill from Fig. 20. Fig. 21 is an enlarged perspective view of the core drill of Fig. 20. Fig. 22 is an enlarged perspective top view of the core drill of Fig. 20. Fig. 23 is an enlarged side view of the core drill from Fig. 20.

[0008] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure may be embodied or practiced in other embodiments and in various ways. It is to be understood that the phrases and terminology used herein are for the purpose of description only and should not be considered limiting. Detailed description

[0009] The Fig. 1 shows a power tool in the form of a core drill 10. The core drill 10 comprises a housing 14 with a motor housing part 18 and a drive housing part 20. A motor 22 ( Fig. 3) is disposed within the motor housing portion 18 of the housing 14 and, in the illustrated embodiment, is a brushless DC motor. In other embodiments, the core drill 10 may also include other motor types. The core drill 10 is cordless and includes a battery 23 that provides power to the motor 22. In other embodiments, the core drill 10 may be a corded tool configured to receive power from an outlet or other remote power source.

[0010] The core drill 10 further includes a primary handle or first handle 24 and an additional handle or second handle 26. The first handle 24 is connected to the motor housing portion 18 and disposed behind the motor housing portion 18. The first handle 24 is configured to be grasped by a user during operation of the core drill 10. The second handle 26 is removably connected to the drive housing portion 20. A trigger 28 is provided on the first handle 24, which, when pressed by a user, starts the motor 22. The trigger 28 may, for example, be a variable speed switch that operatively changes an operating speed of the motor 22 depending on the extent to which the trigger 28 is pulled. In other embodiments, the trigger 28 may be an on-off switch that operatively sets the motor 22 to a preset speed.In any event, the trigger 28 has a home position in which the motor 22 is de-energized and a fully actuated position in which the motor 22 can be operated at a maximum speed for a particular functional setting of the core drill 10, as described in more detail below.

[0011] With reference to the Fig. 3 and Fig. 4, the core drill 10 comprises a spindle 30 rotatable about a rotation axis A1 to receive torque from the motor 22. A tool insert 32 (e.g., a core drill insert; Fig. 1) can be connected to a threaded end 31 of the spindle 30 to rotate with the spindle 30 and perform operations (e.g., core drilling) on a workpiece. In the illustrated embodiment, a locking ring 33 is provided, which allows the user to apply preload to the threaded connection between the spindle 30 and the tool bit 32, thereby securing the tool bit 32. The locking ring 33 can also be operated to release the preload and facilitate removal of the tool bit 32.

[0012] A drive unit 34 is arranged within the drive housing portion 20 of the housing 14 and is configured to transmit torque from an output shaft 38 of the motor 22 to the spindle 30. The illustrated drive unit 34 includes a multi-gear transmission 42 having a first gear or slow gear 44a with a first toothed portion 48a and a second gear or fast gear 44b with a second toothed portion 48b. The slow gear 44a and the fast gear 44b are arranged around a rear end portion of the spindle 30 (opposite the threaded end 31 of the spindle 30) and are rotatable relative to the spindle 30. The slow gear 44a and the fast gear 44b are meshingly connected to and continuously driven by the first and second drive gears (not shown), respectively. The first and second drive gears are attached to an intermediate shaft (not shown).A pinion 50, which in the illustrated embodiment is formed integrally on the output shaft 38, meshes with an intermediate gear 51 (e.g. a helical gear), which is connected to the intermediate shaft (not shown) in order to rotate (. Fig. 3). The intermediate gear 51 may be connected to the intermediate shaft in various ways (e.g., by a key arrangement, an interference fit, a splined connection, etc.). In some embodiments, the intermediate gear 51 may be connected to the intermediate shaft via a clutch mechanism.

[0013] A shift ring 72 is rotationally fixed to the spindle 30 and disposed between the slow gear 44a and the fast gear 44b. As described in more detail below, the shift ring 72 is movable along the axis A1 to selectively engage the slow gear 44a or the fast gear 44b, thereby connecting the selected gear 44a, 44b for common rotation with the spindle 30. In this manner, the shift ring 72 selects which of the gears 44a, 44b drives the spindle 30. The slow gear 44a has a relatively larger number of teeth than the fast gear 44b. In the illustrated embodiment, the shift ring 72 can be switched to a first position in which the shift ring 72 engages the slow gear 44a to define a low-speed, high-torque operating mode of the drive unit 34.The low speed, high torque operating mode provides a first gear ratio between the output shaft 38 and the spindle 30. The shift ring 72 can be switched to a second position in which the shift ring 72 engages the high speed gear 44b to define a high speed, low torque operating mode of the drive unit 34. The high speed, low torque operating mode provides a second gear ratio between the output shaft 38 and the spindle 30 that is smaller than the first gear ratio. In some embodiments, the first gear ratio can be between 10:1 and 20:1, and the second gear ratio can be between 3:1 and 8:1. In some embodiments, the first gear ratio can be between 12:1 and 18:1. In some embodiments, the first gear ratio can be between 14:1 and 17:1.In some embodiments, the second gear ratio may be between 4:1 and 7:1. In some embodiments, the second gear ratio may be between 5:1 and 6:1. In some embodiments, the first gear ratio may be at least 2 times the second gear ratio. In some embodiments, the first gear ratio may be at least 2.5 times the second gear ratio. In some embodiments, the first gear ratio may be at least 3 times the second gear ratio. In some embodiments, the transmission 42 may be configured to shift between more than two gear ratios.

[0014] The core drill 10 also includes a speed selector or electromechanical speed switch 52 having an actuating knob 56, a rod 60 connected to and extending from the actuating knob 56, and a cam 64 also connected to the actuating knob 56. The actuating knob 56 is disposed along the drive housing portion 20 and is configured to be rotated by a user to set an output speed at which the spindle 30 rotates. When the actuating knob 56 is rotated, a spring-loaded pin 66 interacts with one of the four detent pockets 68a-d ( Fig. 5) defined in the housing 14 of the core drill 10. The locking pockets 68a-d define four different speeds at which the core drill 10 can be operated.

[0015] Fig. Figure 6 illustrates a shaft 70 and a sensor assembly 76 disposed within the housing 14 of the core drill 10. The shaft 70 is provided with a pin-shaped or conical end 69 that cooperates with the cam 64 to enable axial displacement of the shaft 70 within the housing 14. A pocket 80 is formed within the shaft 70 and is configured to hold and receive a magnet 84. The sensor assembly 76 includes a Hall sensor board 88 and a Hall effect sensor 92 disposed on the Hall sensor board 88. In other embodiments, the Hall effect sensor 92 may be remotely located and wired to another separate printed circuit board (PCB). The Hall effect sensor 92 is configured to determine a position of the magnet 84 as the shaft 70 moves within the housing 14.The sensor assembly 76 also includes a ferrous metal member 78 disposed along the Hall sensor board 88 to cause the magnetic flux of the magnet 84 to be denser at a top surface of the magnet 84.

[0016] When the actuating knob 56 is rotated, the rod 60 is configured to move the shift ring 72 of the transmission 42 to adjust a gear ratio of the transmission 42. Specifically, the rod 60 pushes the first plate 71a in a rightward direction, thereby biasing a spring 74 against the second plate 71b. When the shift ring 72 is properly aligned with the slow gear 44a, the shift ring 72 moves on the first gear portion 48a to engage the slow gear 44a. If the shift ring 72 is not properly aligned, the stored bias of the spring 74 acts on the second plate 71b and the shift ring 72. The second plate 71b and the shift ring 72 then move once the slow gear 44a is moved into alignment with the shift ring 72. Thus, a user can set a desired position of the actuating knob 56 without manipulating the spindle 30.

[0017] The cam disc 64 is designed to rotate with the actuating knob 56, so that the shaft 70 is displaced to enable the movement of the magnet 84. The movement of the magnet 84 adjusts an output of the Hall-effect sensor 92 to supply the motor 22 with different current intensities, thus electronically changing the speed of the motor 22 without having to change the gear ratio of the gearbox 42. The magnetic flux generated by the magnet 84 and detected by the Hall-effect sensor 92 is in Fig. 18, where Fig. Figure 17 illustrates that the magnetic flux detected by the Hall effect sensor 92 varies depending on the displacement of the shaft 70 and the magnet 84.

[0018] When the operating button 56 is in a first position ( Fig. 4-6), the indexing ring 72 is moved to engage the slow gear 44a, placing the drive unit 34 in the low speed, high torque operating mode. The magnet 84 is disposed in a first right-hand position such that the Hall effect sensor 92 measures a positive magnetic field and a controller (which may be implemented, for example, as a microprocessor, machine-readable non-transitory memory, and switching electronics such as FETs to control power output to the motor 22) controls the motor 22 to operate at a first motor speed (in some embodiments, e.g., 16,000 rpm - 17,000 rpm) when the trigger 28 is fully depressed. Thus, the first position of the actuation button 56 defines a first speed position of the core bit 10. In some embodiments, the spindle 30 may rotate at a maximum speed between 800 rpm and 1,000 rpm.200 rpm, between 900 rpm and 1,100 rpm or from about 1,000 rpm when the core drill 10 is in the first speed position.

[0019] To increase the speed of the spindle 30, the operating knob 56 can be rotated (e.g. counterclockwise) to be arranged in a second position ( Fig. 7-9). In the second position, the shift ring 72 remains engaged with the slow gear 44a, so that the gear ratio of the gear 42 is not changed. When the cam 64 rotates with the actuating knob 56, the shaft 70 is displaced such that the magnet 84 moves in a first direction, or a left direction. The Hall effect sensor 92 measures a neutral magnetic field and communicates with the controller to electronically change the speed of the motor 22 from the first speed to a second motor speed (e.g., 26,000-27,000 rpm) that is greater than the first speed when the trigger 28 is fully depressed. Thus, the second position of the actuation button 56 defines a second speed position of the core drill 10. In some embodiments, the spindle 30 can rotate at a maximum speed between 1,400 rpm and 1,800 rpm, between 1,500 rpm and 1,800 rpm.700 rpm or approximately 1,600 rpm when the core drill 10 is in the second speed position.

[0020] If the operating knob 56 is further turned counterclockwise to reach a third position ( Fig. 10-12), the shift ring 72 is moved to engage the high-speed gear 44b and change the gear ratio of the gearbox 42 to the high-speed, low-torque operating mode. The shaft 70 is translated such that the magnet 84 moves further to the left. The Hall effect sensor 92 indicates a negative magnetic field, and the motor 22 is operated by the controller at a third speed (e.g., 14,500 rpm - 15,500 rpm) when the trigger 28 is fully depressed. Thus, the third position of the actuation button 56 defines a third speed position of the core drill 10. In some embodiments, the third motor speed is lower than the first and second motor speeds. In some embodiments, the third motor speed may be equal to the first motor speed.In some embodiments, the third motor speed may be greater than the first motor speed and less than the second motor speed. In some embodiments, the spindle 30 may rotate at a maximum speed between 2,300 rpm and 2,900 rpm, between 2,500 rpm and 2,700 rpm, or approximately 2,600 rpm when the core drill 10 is in the third speed position.

[0021] If the operating knob 56 is turned further to a fourth position ( Fig. 13-15), the shift ring 72 remains engaged with the high-speed gear 44b so that the gear ratio of the gearbox 42 is not changed. Again, the shaft 70 is translated by the rotation of the cam 64 so that the magnet 84 moves in a second, or right, direction. The Hall effect sensor 92 indicates a neutral magnetic field, and the motor 22 is operated by the controller at a fourth speed (e.g., 26,000 rpm - 27,000 rpm) when the trigger 28 is fully depressed. Thus, the fourth position of the actuation button 56 defines a fourth speed position of the core drill 10. In some embodiments, the fourth motor speed is greater than the first and third motor speeds. In some embodiments, the fourth motor speed may be equal to the second motor speed.In some embodiments, the fourth motor speed may be greater or less than the second motor speed. In some embodiments, the spindle 30 may rotate at a maximum speed between 3,500 rpm and 5,500 rpm, between 4,000 rpm and 5,000 rpm, or approximately 4,570 rpm when the core drill 10 is in the fourth speed position.

[0022] It has been found that the first, second, third, and fourth speed settings described above provide optimal performance when the core drill bits 32 are of different sizes. The core drill 10 in Fig. 2 is provided with indicators 89 surrounding the operating knob 56 at various positions corresponding to the four respective speed settings. The indicators 89 indicate a nominal size or size range of various core drilling inserts 32 that can be mounted on the spindle 30.In some embodiments, the indicators 89 may indicate that the first position of the actuation knob 56 and the first speed position corresponds to core bits 32 with a diameter of 3-4 inches, the second position of the actuation knob 56 and the second speed position corresponds to core bits 32 with a diameter of 2-3 inches, the third position of the actuation knob 56 and the third speed position corresponds to core bits 32 with a diameter of 1-2 inches, and the fourth position of the actuation knob 56 and the fourth speed position corresponds to core bits 32 with a diameter of less than 1 inch. In this manner, the electromechanical speed switch 52 provides the core drill 10 with four easily accessible speed positions optimized for different bit sizes, while requiring only two mechanical gear positions.However, the electromechanical speed switch 52 as described above may also be incorporated into other types of power tools.

[0023] As with reference to Fig. 1, the core drill 10 comprises a fluid distribution system 93. The fluid distribution system 93 has a first connection element 94, a second connection element 95, which is connected to the motor housing part 18, and a control valve 96, which is also connected to the motor housing part 18. The first connection element 94 can be connected to a supply line (not shown) in order to provide the fluid distribution system 93 with a fluid (e.g., water) from an external source (not shown). A supply line 97 extends from the second connection element 95 into the drive housing part 20 and is connected to a third connection element 98 ( Fig. 3) of the fluid distribution system 93. The control valve 96 is arranged between the first and second connection elements 94, 95 to regulate the fluid flow from the supply line to the delivery line 97. The control valve 96 has a handle 99 that can be moved by the user between a first and a second position. In the first position, the control valve 96 is in an off state in which the fluid flow from the first connection element 94 to the second connection element 95 is blocked. In the second position, the control valve 96 is in an on state in which fluid flow from the first connection element 94 to the second connection element 95 is permitted. During the on state, fluid can therefore flow through the supply line 97 and to the spindle 30 to cool, lubricate, and dedust the tool insert 32.

[0024] Fig. 16 illustrates another electromechanical speed switch 152 incorporated in the core drill 10 from Fig. 1. The electromechanical speed switch 152 can also be installed in other types of power tools. The electromechanical speed switch 152 is similar to the electromechanical speed switch 52 of the Fig. 1-15; therefore, the same structure is identified by the same reference number plus "100". The differences between the electromechanical speed switch 152 of the Fig. 16 and the electromechanical speed switch of the Fig. 1-15 are discussed below.

[0025] The electromechanical speed switch 152 includes a cam 156 and a shaft 170. The shaft 170 is formed with a T-shaped end 202 that is designed to cooperate with the cam 156 to allow axial displacement of the shaft 170 within the housing 14. Compared to the shaft 70, the T-shaped end 202 of the shaft 170 Fig. 16 provides a larger contact area between the shaft 170 and the cam 156 in different positions of the shaft 170 when the cam 156 is rotated by the operating knob (not shown).

[0026] The Fig. 19-23 show another embodiment of a core drill 310. The core drill 310 is similar to the core drill 10 of Fig. 1-15; therefore, the same structure is identified by the same reference number plus "300". The differences between the core drill 310 of the Fig. 19-23 and the core drill 10 of the Fig. 1-15 are discussed below; however, it should be understood that features and elements of the core drill 10 can be incorporated into the core drill 310 and vice versa.

[0027] With reference to the Fig. 19 and Fig. 20, the core drill 310 comprises a housing 314, a part of which is inserted into the Fig. 20-23. The housing 314 is made of a first material, e.g., a plastic or composite material, and may be defined by cooperating housing shell halves. The illustrated housing 314 has a motor housing portion (which surrounds a motor 322 of the core drill 310) and a drive housing portion 320 (which surrounds a drive unit 334 of the core drill 310). The drive unit 334 is configured to transmit torque from an output shaft 338 of the motor 322 to a spindle 330. A tool bit (e.g., a core drill bit; not shown) may be connected to the spindle 330 to rotate with the spindle 330 and perform work (e.g., drilling) on a workpiece. The drive unit 334 includes a multi-speed gearbox 342 similar to the one described above with reference to FIGS. Fig. 1-15. The multi-speed gear 342 is disposed within a gear housing 402, which in turn is held within the drive housing portion 320 of the housing 314. In the illustrated embodiment, the gear housing 402 is made of a second material (e.g., a metal such as steel, aluminum, magnesium, etc.) that is different from the first material of the housing 314.

[0028] With reference to the Fig. 21 and Fig. 22, the illustrated core drill 310 further includes an electromechanical speed switch 352, a shaft 370, and a sensor assembly 376. The speed switch 352 has an actuation knob 356 and a cam 364 connected to the actuation knob 356 for rotation therewith. The actuation knob 356 is configured to be rotated by a user to set an output speed at which the spindle 330 rotates. The cam 364, the shaft 370, and the sensor assembly 376 are disposed outside the gear housing 402 and thus between the gear housing 402 and the housing 314. In other embodiments, the arrangement of the speed switch 352, the shaft 370, and the sensor assembly 376 along the housing 314 of the core drill 310 may vary.

[0029] With reference to Fig. 23, the shaft 370 is formed with a T-shaped end 404 configured to cooperate with the cam 364 to enable axial displacement of the shaft 370 in response to rotation of the cam 364. More specifically, the T-shaped end 404 engages a circular projection 408 extending eccentrically from a plate portion 412 of the cam 364. A pocket (not shown) is defined in the shaft 370 and configured to hold and receive a magnet 384 ( Fig. 22). The sensor assembly 376 includes a Hall sensor board 388 and a Hall effect sensor 392. The Hall sensor board 388 is mounted on a bracket 416 that is secured to the transmission housing 402. The Hall effect sensor 392 is disposed on the Hall sensor board 388. In other embodiments, the Hall effect sensor 392 may be remotely located and wired to another separate circuit board. The Hall effect sensor 392 is configured to determine a position of the magnet 384 as the shaft 370 moves within the housing 314.

[0030] The cam 364 is configured to rotate with the actuation knob 356. When the actuation knob 356 is rotated, the cam 364 also rotates, displacing the shaft 370 to move the magnet 384. The movement of the magnet 384 is detected via the change in an output signal of the Hall effect sensor 392, and a controller of the core drill 310 is configured to supply the motor 322 with different voltages and / or currents (including, but not limited to, PWM signals with different duty cycles, etc.) to electrically change the speed of the motor 322 without having to change the gear ratio of the transmission. In the illustrated embodiment, rotation of the actuating knob 356 is also configured to adjust a gear ratio of the gear box 342 in a similar manner as described above with respect to the core drill 10 of the Fig. 1-15 described.

[0031] During the rotation of the cam disc 364, a spring-loaded pin 366 ( Fig. 20) interacts with the cam 364. More specifically, the spring-loaded pin 366 interacts with one of a plurality of detent pockets (not shown) defined within the cam 364. The plurality of detent pockets define various switch positions corresponding to different speeds at which the core bit 310 can be operated. In the illustrated embodiment, the spring-loaded pin 366 extends from a projection 420 formed on the gear housing 402. In other embodiments, the spring-loaded pin 366 may extend from the actuation button 356.

[0032] Although the disclosure has been described in detail with reference to certain preferred embodiments, as described, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure.

[0033] Various features and aspects of the disclosure are set forth in the following claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 683,123

[0001] US 63 / 623,066

[0001]

Claims

[1] A power tool comprising: a housing; a motor mounted in the housing; a transmission operatively connected to the engine, the transmission switchable between a low-speed, high-torque operating mode and a high-speed, low-torque operating mode; a spindle configured to receive torque from the motor via the gearbox; a speed switch having a movable selector switch for switching the transmission between the low-speed, high-torque operating mode and the high-speed, low-torque operating mode, a shaft movable in response to movement of the selector switch, and a magnet connected to the shaft; and a controller configured to change an operating speed of the motor based on a determined position of the magnet. [2] The power tool of claim 1, wherein the speed switch further comprises a cam connected to and movable by the switch, and wherein the shaft is configured to be axially displaced by movement of the cam to change the operating speed of the motor. [3] The power tool of claim 2, wherein the shaft has a pocket configured to receive the magnet. [4] The power tool according to claim 2 or 3, wherein the shaft is formed with a tapered end which engages with the cam disc. [5] The power tool according to claim 2 or 3, wherein the shaft is formed with a T-shaped end which engages with the cam disc. [6] The power tool according to any one of the preceding claims, wherein the changeover switch is movable between a first position, a second position, a third position and a fourth position, each corresponding to a different maximum speed of the spindle. [7] The power tool of claim 6, wherein the transmission is in the low speed, high torque mode of operation when the selector switch is in the first and second positions, and wherein the transmission is switched to the high speed, low torque mode of operation when the selector switch is in the third and fourth positions. [8] The power tool of claim 1, wherein the transmission includes a shift ring movable by the speed switch to engage a first gear or a second gear to switch between the low speed, high torque operating mode and the high speed, low torque operating mode. [9] A power tool comprising: a housing; a motor mounted in the housing; a gear housing held in the housing; a transmission disposed in the transmission housing and operatively connected to the engine, the transmission switchable between a low-speed, high-torque operating mode and a high-speed, low-torque operating mode; a spindle configured to receive torque from the motor via the gearbox; a movable switch for switching the transmission between the low-speed, high-torque operating mode and the high-speed, low-torque operating mode; a cam connected to and movable with the switch; a shaft configured to be axially displaced by the movement of the cam; and a controller configured to vary an operating speed of the motor in response to the displacement of the shaft, wherein the cam and the shaft are arranged between the housing and the gear housing. [10] The power tool of claim 9, further comprising a sensor assembly disposed between the housing and the gear housing, the sensor assembly configured to determine a position of a magnet carried by the shaft. [11] The power tool of claim 10, wherein the sensor assembly comprises a Hall effect sensor configured to output a signal to the controller. [12] The power tool according to any one of claims 9 to 11, wherein the housing is defined by cooperating shell halves. [13] The power tool according to any one of claims 9 to 12, wherein the housing is made of a first material, and wherein the gear housing is made of a second material different from the first material. [14] The power tool according to claim 13, wherein the first material is a plastic and the second material is a metal. [15] A power tool comprising: a housing; a motor mounted in the housing; a transmission operatively connected to the engine, the transmission having a first gear, a second gear, and a shift ring configured to engage the first gear or the second gear; a spindle configured to receive torque from the motor via the gearbox; a rotary switch for moving the switching ring to engage the first gear or the second gear; a shaft configured to be axially displaced by rotation of the switch; and a sensor assembly configured to detect a position of a magnet carried by the shaft to electronically change an operating speed of the motor. [16] The power tool of claim 15, wherein the sensor assembly comprises a sensor board and a Hall effect sensor disposed on the sensor board, the Hall effect sensor configured to determine the position of the magnet. [17] The power tool according to claim 15 or 16, wherein the changeover switch is rotatable to a first position in which the switching ring is moved to engage the first gear so that the operating speed of the motor is a first operating speed. [18] The power tool of claim 17, wherein the changeover switch is rotatable to a second position in which the switching ring remains engaged with the first gear and the shaft is axially displaced to thereby move the magnet in a first direction such that the operating speed of the motor is a second operating speed. [19] The power tool of claim 18, wherein the changeover switch is rotatable to a third position in which the switching ring is moved to engage the second gear and the shaft is axially displaced to thereby move the magnet further in the first direction such that the operating speed of the motor is a third operating speed. [20] The power tool of claim 19, wherein the changeover switch is rotatable to a fourth position in which the switching ring remains engaged with the second gear and the shaft is axially displaced to thereby move the magnet in a second direction such that the operating speed of the motor is a fourth operating speed.

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