Power tool attachment component

Abstract

A power tool attachment component for a power tool includes an elongated housing including an upper housing portion and a lower housing portion interconnected with the upper housing portion, an input gear configured to be connected to an output shaft of a power wrench, an output gear configured to be connected to an output shaft of the power wrench, a first intermediate gear coupled to the input gear, and a torque sensor coupled to the lower housing portion. An input gear is disposed at a first end of the housing, an output gear has an output interface, the output gear is disposed at a second end of the housing, a first intermediate gear is disposed inside the housing and configured to transmit torque of the input gear to the output gear, the first intermediate gear is rotatably mounted on a first intermediate gear shaft, and a second intermediate gear is disposed inside the housing and configured to transmit torque of the output gear to the first intermediate gear shaft. A torque sensor configured to detect a radial force acting on the first intermediate gear shaft, thereby obtaining a measurement of torque at the output gear; the axis of the input gear, the axis of the output gear and the axis of the first intermediate gear are parallel to the axis of the output shaft of the power wrench, and the input gear, the output gear and the first intermediate gear are located on the same level.

Description

[0001] This application is a divisional application of the invention patent application with application number 202080052693.2, application date July 6, 2020, and invention name “Power Tool Attachment Part”. Technical Field

[0002] The present invention relates to a power tool attachment component for a power tool. Background Art

[0003] Power tool attachments are often used in confined spaces where ordinary power tools cannot be used to access the bolts or nuts of the joints to be tightened. Power tool attachments are also known as claws, front attachments, or offset attachments.

[0004] The power tool attachment component includes a plurality of gears that transmit rotational motion from an input gear to an output gear. The gears are usually arranged in a row of teeth against teeth inside an elongated housing.

[0005] Torque in a power tool is typically measured by a sensor disposed inside the power tool. However, internal measurements in a power tool may not provide an accurate measurement of the torque experienced by a power tool attachment component attached to the power tool.

[0006] EP3388199 discloses a screwing device comprising a claw connected to the screwing device. The claw has a helical gear with angled teeth. The claw comprises a torque sensor configured to measure the torque of a gear arranged adjacent to an output gear. The torque measurement is based on the axial movement of the helical gear, and the sensor uses a load cell to determine the torque.

[0007] A helical gear tooth structure is required to make torque measurements. However, there are claws that utilize other gear designs, such as spur gears with straight teeth. Summary of the invention

[0008] It is an object of the present invention to provide an attachment member by which the problems of the prior art are solved or at least alleviated.

[0009] Therefore, a power tool attachment component for a power tool is provided, comprising: an elongated housing, an input gear, an output gear, a first intermediate gear and a torque sensor, wherein the elongated housing comprises an upper housing portion and a lower housing portion interconnected with the upper housing portion, the input gear is configured to be connected to an output shaft of a power wrench, the input gear is arranged at a first end of the housing, the output gear has an output interface, the output gear is arranged at a second end of the housing, the first intermediate gear is arranged on the inner side of the housing and is configured to transmit the torque of the input gear to the output gear, the first intermediate gear is rotatably mounted on a first intermediate gear shaft, the torque sensor is configured to detect a radial force acting on the first intermediate gear shaft, thereby obtaining a measurement of the torque at the output gear; wherein the axis of the input gear, the axis of the output gear and the axis of the first intermediate gear are parallel to the axis of the output shaft of the power wrench, and the input gear, the output gear and the first intermediate gear are at the same level.

[0010] Therefore, the torque sensor is configured to detect and sense the radial force acting on the first intermediate gear shaft when the torque is transmitted to the output gear via the first intermediate gear. In this way, correct torque measurement can be achieved regardless of the gear tooth configuration of the first intermediate gear, the input gear, the output gear and any additional intermediate gears. Therefore, all gears can be provided with straight teeth, so-called spur gears. This provides an important advantage since such spur gears are easier to manufacture and cheaper than helical gears with helical teeth required by the prior art. However, radial force detection also allows the gears to have any other suitable gear tooth configuration, such as helical gears, if it is considered advantageous for other reasons.

[0011] The torque sensor can be configured to measure radial deformation of the first gear shaft. Such radial deformation can be accurately determined by simple and well-proven components such as piezoelectric elements and strain gauges.

[0012] The first intermediate gear can preferably mesh with the output gear. In this way, the torque is measured to be close to the actual output torque, so that the correct value of the output torque can be easily calculated.

[0013] The first idler gear shaft may be hollow, and the torque sensor may be accommodated in the first idler gear shaft.

[0014] The torque sensor may include a piezoelectric element.

[0015] Alternatively or in combination, the torque sensor may comprise a strain gauge.

[0016] The power tool attachment component may further include a plurality of second intermediate gears arranged inside the housing and configured to transfer the torque of the input gear to the output gear. By selecting the number of intermediate gears, the length of the attachment component can be adapted to different applications.

[0017] The input gear, the output gear and the intermediate gear may be spur gears.

[0018] Each intermediate gear may be mounted to a corresponding intermediate gear shaft via a needle bearing.

[0019] The power tool attachment component may further include an electronics unit configured to receive measurements from the torque sensor.

[0020] The electronics unit may be configured to supply power to the torque sensor.The electronics unit may, for example, comprise a battery or be configured to be connected via a line to drive electronics of the power tool or a control unit of the power tool.

[0021] The electronic unit may be configured to process the measurements.Thus, the electronic unit may comprise a processing circuit configured to process the measurements, for example to determine the torque based on the measurements of the radial forces acting on the first intermediate gear shaft.

[0022] The electronic unit may be configured to transmit the measurement results to a control unit of the power tool.

[0023] According to one embodiment, the power tool attachment component is a claw.

[0024] Other features and advantages of the present invention will be apparent from the accompanying drawings and detailed description of the illustrated embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the following detailed description, reference is made to the accompanying drawings, in which:

[0026] Figure 1 A perspective view showing an example of a power tool attachment component;

[0027] Figure 2 yes Figure 1 An exploded view of the power tool attachment components in FIG.

[0028] Figure 3 yes Figure 1 A longitudinal cross-sectional view of a power tool attachment component in FIG. DETAILED DESCRIPTION

[0029] Figure 1 An example of a power tool attachment component 1 for a power tool is depicted. The power tool may be, for example, a wrench or a nut runner.

[0030] An exemplary power tool attachment component 1 is a claw. The power tool attachment component 1 comprises an elongated housing 3. The elongated housing 3 comprises an upper housing portion or first housing portion 3a and a lower housing portion or second housing portion 3b. The upper housing portion 3a and the lower housing portion 3b are connected to each other.

[0031] Figure 2 The power tool attachment part 1 is shown in the form of an exploded view. The power tool attachment part 1 includes an input gear wheel or a shorter input gear 9 and an output gear 11 arranged in an elongated housing 3. The input gear 9 is arranged at a first end of the elongated housing 3. The output gear 9 is arranged at a second end of the housing 3.

[0032] The input gear 9 is drivingly connected to the output gear 11 via a plurality of intermediate gears 13a, 13b. In the example shown, there are five intermediate gears, including a first intermediate gear 13a meshing with the output gear 11 and four second intermediate gears arranged between the input gear 9 and the first intermediate gear 13a for transmitting rotation and torque therebetween. However, as long as there is one first intermediate gear 13, the number of intermediate gears can be freely varied to suitably adapt the length of the claw. The number of second intermediate gears 13b can therefore be any integer from zero and above. In the example shown, all gears are spur gears.

[0033] The output gear 11 comprises an output connection portion or interface 11a. The output interface 11a may be configured to receive, for example, a wrench bit, a screwdriver bit, a nut or a screw head.

[0034] The first intermediate gear 13a is rotatably mounted to the first intermediate gear shaft 15a via a needle bearing 16a. Accordingly, each second intermediate gear 13b is rotatably mounted to the second intermediate gear shaft 15b via a corresponding needle bearing 16b.

[0035] The first intermediate gear shaft 15a is hollow. In the example shown, it has a cylindrical inner hole 17a, which extends axially from one end of the first intermediate gear shaft 15a to the other end. However, in alternative embodiments, the hollow configuration of the first intermediate gear shaft can be achieved by an inner space of any cross-sectional geometry, which may or may not extend over the entire axial length of the first intermediate shaft.

[0036] The torque sensor 19 is housed in the inner hole 17a. In the example shown, the torque sensor is formed by a piezoelectric element which is inserted into the inner hole and fixed therein by any suitable means, for example by gluing, press fitting or by additional fixing elements. In the example shown, the piezoelectric element has substantially the same cross-sectional geometry as the inner hole 17a.

[0037] The piezoelectric element is configured to detect radial deformation of the first intermediate gear shaft 15a and generate an electrical signal proportional to the radial deformation. This radial deformation occurs when the input torque is transmitted from the input gear to the first intermediate gear 13a via the second intermediate gear 13b and when the output gear generates a reaction torque relative to the first intermediate gear 13a. The deformation of the first intermediate gear shaft 15a and thus the signal generated by the torque sensor 19 are proportional to the reaction torque generated by the output gear 11, so that the actual torque acting on the output gear can be calculated.

[0038] In an alternative embodiment not shown, the torque sensor is formed by or includes a strain gauge, which is accommodated in the inner space of the first intermediate gear shaft. The strain gauge can, for example, include a thin film sensor fixed to the inner wall of the first intermediate gear shaft or to a pin, needle, etc. inserted into the inner space of the first intermediate gear shaft.

[0039] The power tool attachment component 1 may optionally include an electronic unit 7. The torque sensor 19 is connected to the electronic unit 7 via a line 7a. The electronic unit 7 may be configured to supply power to the torque sensor 19. The electronic unit 7 may be configured to receive measurement results from the torque sensor 19. The electronic unit 7 may be configured to process the measurement results from the torque sensor 19. For example, the electronic unit 7 may be configured to process the measurement results or detection results obtained by the piezoelectric element and determine the torque corresponding to the radial deformation of the first intermediate gear shaft 15a.

[0040] The electronic unit 7 may be configured to communicate wirelessly or by wire with the power tool and / or with a control unit configured to control the operation of the power tool. The electronic unit 7 may be configured to transmit unprocessed measurements and / or processed measurements. Optionally, the electronic unit 7 may include a display unit 7b configured to display processed measurements from the torque sensor 19. The electronic unit 7 may be arranged on an outer surface of the elongated housing 3, for example on the upper housing portion 3a.

[0041] The torque sensor 19 may alternatively be configured to be electrically connected directly to the power tool and powered by the power tool.

[0042] In the embodiment shown in the figure, the first intermediate gear meshes with the output gear. This may be preferred because the signal generated by the torque sensor closely corresponds to the actual torque acting on the output gear. However, in an alternative embodiment, the first intermediate gear can be any intermediate gear so that it meshes with one or both of the input gear and / or the second intermediate gear. In such an alternative, when determining the actual torque acting on the output gear, it is necessary to compensate for the friction generated at the gear mesh between the first intermediate gear and the output gear.

[0043] The electronic unit 7 may include a processing circuit configured to process the measurements from the torque sensor 19. Further, the electronic unit 7 may include a storage medium including computer code which, when executed by the processing circuit, causes the electronic unit 7 to determine the torque at the output gear based on the measurements from the torque sensor 5. The processing circuit may be configured to display the determined torque on a display 7 b of the electronic unit 7.

[0044] The processing circuitry may use any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., which is capable of performing any of the operations disclosed herein related to determining torque based on the measurement results obtained by the torque sensor 19.

[0045] The storage medium may be embodied, for example, as a memory such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM), and more specifically as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a flash memory (e.g., Compact Flash).

[0046] For example, the electronic unit 7 may comprise a transmitter configured to wirelessly transmit measurements received from the torque sensor to the power tool or a control unit of the power tool.

[0047] Above, the inventive concept has been described with reference to two specific embodiments. However, the inventive concept is not limited to any one of these embodiments. It will be apparent to those skilled in the art that the inventive concept can be modified within its scope, which is defined by the appended claims.

Claims

1. A power tool attachment component (1) for a power tool, comprising: - an elongated housing (3), comprising an upper housing portion (3a) and a lower housing portion (3b) interconnected with the upper housing portion (3a), - an input gear (9) configured to be connected to an output shaft of the power wrench, said input gear (9) being arranged at a first end of the housing (3), - an output gear (11) having an output interface (11a), the output gear (11) being arranged at the second end of the housing (3), - a first intermediate gear (13a) arranged inside the housing (3) and configured to transmit the torque of the input gear (9) to the output gear (11), the first intermediate gear (13a) being rotatably mounted on a first intermediate gear shaft (15a), and - a torque sensor (19) configured to detect radial forces acting on said first intermediate gear shaft (15a) so as to obtain a measurement of the torque at the output gear (11); The axes of the input gear (9), the output gear (11) and the first intermediate gear (13a) are parallel to the axis of the output shaft of the power wrench, and the input gear (9), the output gear (11) and the first intermediate gear (13a) are at the same level.

2. The power tool attachment component according to claim 1, wherein: The torque sensor (19) is configured to measure radial deformation of the first gear shaft (15a).

3. The power tool attachment component according to claim 1 or 2, wherein: The first intermediate gear (13a) meshes with the output gear (11).

4. The power tool attachment component according to any one of claims 1 to 3, wherein: The first intermediate gear shaft (15a) is hollow, and the torque sensor (19) is accommodated in the first intermediate gear shaft (15a).

5. The power tool attachment component according to any one of claims 1 to 4, wherein: The torque sensor (19) comprises a piezoelectric element.

6. The power tool attachment component according to any one of claims 1 to 5, wherein: The torque sensor includes a strain gauge.

7. The power tool attachment component according to any one of claims 1 to 6, further comprising a plurality of second intermediate gears (13b) arranged inside the housing (3) and configured to transmit the torque of the input gear (9) to the output gear (11).

8. The power tool attachment component according to any one of claims 1 to 7, wherein: The input gear (9), the output gear (11) and the intermediate gears (13a, 13b) are spur gears.

9. The power tool attachment component according to any one of claims 1 to 8, wherein: Each intermediate gear (13a, 13b) is mounted to a corresponding intermediate gear shaft (15a, 15b) via a needle bearing (16a, 16b).

10. A power tool attachment component according to any one of claims 1 to 9, comprising an electronic unit (7) configured to receive measurements from the torque sensor (19).

11. The power tool attachment component according to any one of claims 1 to 10, wherein: The electronic unit (7) is configured to supply power to the torque sensor (19).

12. The power tool attachment component according to claim 11, wherein: The electronic unit (7) is configured to process the measurement results.

13. The power tool attachment component according to any one of claims 10 to 12, wherein: The electronic unit (7) is configured to transmit the measurement results to a control unit of the power tool.

14. The power tool attachment component according to any one of claims 1 to 13, wherein: The power tool attachment component (1) is a claw-shaped component.

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