Rotational position detection device

Abstract

A rotational position detection device includes an coded gear and a plurality of Hall sensors. The coded gear includes a wheel portion and at least one sensing portion. The number of Hall sensors exceeds the number of the at least one sensing portion and is equiangularly arranged around an axis of the wheel portion. Each Hall sensor senses the movement of the at least one sensing portion and outputs a sensing signal. A central angle is defined as the central angle corresponding to the arc length extending circumferentially along the axis. The central angle corresponding to the distance between the center points of two adjacent Hall sensors is smaller than the central angle corresponding to the at least one sensing portion. Therefore, this invention can achieve high-speed and high-precision measurement while also having the advantages of long service life and no need for complex and time-consuming installation.

Description

Technical Field

[0001] This invention relates to a position detection device, and more particularly to a rotational position detection device. Prior Technology

[0002] During motor operation, its rotational position needs to be detected in real time or its rotational speed needs to be calculated to achieve precise control. Current rotor angle sensors, such as those shown in Figures 1 and 2, involve a sensing gear 12 mounted on a shaft 112 of a rotor 111 of a motor 11, and a Hall sensor 13 positioned on a housing 113 of the motor 11 corresponding to the sensing gear 12. The sensing gear 12 has a plurality of teeth 121. When the sensing gear 12 rotates, the Hall sensor 13 senses the rotation of the teeth 121 and outputs a corresponding sensing signal. The rotational speed can then be calculated based on this sensing signal. However, this sensing technology can only sense the rotational speed and cannot determine the current rotational position of the rotor 111. Furthermore, in high-speed operating environments (e.g., over 10,000 revolutions per minute), the Hall sensor 13 may not be able to detect the rotation in time due to insufficient reaction speed, leading to significant errors in the sensing results and potentially causing motor 11 control failure.

[0003] To address the aforementioned issues, optical corner clearers offer high resolution and accuracy, and can sense the current rotational position of the rotor 111. However, optical corner clearers are less resistant to contaminants such as oil fumes and dust. After prolonged use in an open environment, the optical components are easily contaminated, leading to photosensitive failure, which in turn causes the motor 11 to malfunction or become inaccurately controlled. Furthermore, during installation, the optical corner clearer requires high-precision alignment and calibration of the light emitting and receiving elements, making the installation process complex and time-consuming. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a rotational position detection device that can solve the above-mentioned problems.

[0005] Therefore, the rotation position detection device of the present invention includes an coded gear and a plurality of Hall sensors.

[0006] The coded gear includes a wheel portion and at least one sensing portion disposed on the wheel portion. When the wheel portion rotates about its own axis, the at least one sensing portion rotates around the axis. The at least one sensing portion is made of a magnetically conductive material or a magnetic material.

[0007] The number of Hall sensors is greater than that of the at least one sensing element, their positions correspond to the at least one sensing element, and they are arranged at equal angles around the axis. Each Hall sensor is used to sense the movement of the at least one sensing element and output a sensing signal. The central angle corresponding to the circumferential arc length along the axis is defined as a central angle. The central angle corresponding to the distance between the center points of two adjacent Hall sensors is smaller than the central angle corresponding to the at least one sensing element.

[0008] The advantage of this invention lies in the fact that, through the above-described arrangement, the arrangement of the sensing elements detected by the Hall sensors is different at different angles of the encoded gear. Therefore, the current rotational position of the encoded gear can be determined based on the arrangement of the sensing elements, and the rotational speed can be further calculated based on the position change. Thus, this embodiment can achieve both high-speed and high-precision measurement, while also having the advantages of long service life and no need for complex and time-consuming installation. Simple Explanation of the Diagram

[0009] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figures 1 and 2 are schematic diagrams of a conventional rotor angle sensor applied to a motor; Figure 3 is a schematic diagram of an embodiment of the rotational position detection device of the present invention applied to a motor; and Figure 4 is a schematic diagram of this embodiment, illustrating the positional correspondence between the complex sensing units of an coded gear and the complex Hall sensors. Implementation

[0010] Referring to Figures 3 and 4, one embodiment of the rotational position detection device of the present invention is applicable to detecting the rotational position of a rotor 91 of a motor 9, or further calculating the rotational speed of the rotor 91. The motor 9 includes the rotor 91, a shaft 92 connecting the rotor 91, a stator 93 that allows the rotor 91 to rotate relative to it, a housing 94, and a cover 95 that cooperates with the housing 94 to cover the rotor 91 and the stator 93.

[0011] This embodiment includes an encoded gear 2 and multiple Hall sensors 3, and optionally also includes a controller 4.

[0012] The encoding gear 2 includes a wheel portion 21 adapted to be disposed on the rotating shaft 92, and at least one sensing portion 22 disposed on the wheel portion 21. When the wheel portion 21 rotates about its own axis L in conjunction with the rotating shaft 92, the at least one sensing portion 22 rotates about the axis L. The at least one sensing portion 22 is made of a magnetically conductive material or a magnetic material.

[0013] In this embodiment, the encoding gear 2 is described with four sensing units 22, specifically the first sensing unit 221, the second sensing unit 222, the third sensing unit 223, and the fourth sensing unit 224. However, the encoding gear 2 may include one, two, three, or more than five sensing units 22 depending on actual needs, and is not limited thereto. In one embodiment, when the encoding gear 2 has only one sensing unit 22, it includes only the first sensing unit 221 shown in FIG. 4.

[0014] In this embodiment, the sensing elements 22 extend radially from the wheel portion 21, forming a tooth-like shape similar to the coded gear 2, as described. However, the sensing elements 22 may also be located near the circumference of the wheel portion 21. It is sufficient that they can be used with the Hall sensors 3 and sensed by them.

[0015] A central angle is defined as the central angle corresponding to the arc length extending circumferentially along the axis L. The central angle (denoted as θ1 in Figure 4) is the same for each sensing element 22. Specifically, the central angle θ1 for each sensing element 22 is set such that, when the encoding gear 2 rotates at a constant speed, the time it takes for each sensing element 22 to be sensed by T Hall sensors 3 is the same as the time it takes for it to be sensed simultaneously by T+1 adjacent Hall sensors 3. T is a natural number, and can be, for example, 1, 2, 3, etc. In this embodiment, the central angle θ1 for each sensing element 22 is set such that, when the encoding gear 2 rotates at a constant speed, the time it takes for each sensing element 22 to be sensed by a single Hall sensor 3 is the same as the time it takes for it to be sensed simultaneously by two adjacent Hall sensors 3. In conjunction with the sensing range of the existing Hall sensor 3, the center angle θ1 corresponding to the sensing part 22 will be set as the center angle corresponding to the distance between the center points of two adjacent Hall sensors 3 (represented by θ2 in Figure 4) multiplied by about 3 / 2 (approximately 27 / 20~33 / 20), that is, θ1≒(θ2)*3 / 2.

[0016] Specifically, the central angle θ1 corresponding to each sensing element 22 must be different from the central angle corresponding to the distance between two adjacent sensing elements 22 (represented as θ3 in Figure 4). For example, it can be greater than or less than θ3. In this embodiment, it is explained that the central angle θ1 corresponding to each sensing element 22 is less than the central angle θ3 corresponding to the distance between adjacent sensing elements 22.

[0017] Here, the number of sensing elements 22 is defined as n, where n is a natural number greater than 1, and h is a natural number between 1 and n-1. The central angle corresponding to the minimum distance between the h-th sensing element 22 and the (h+1)-th sensing element 22 is M+P. M is a predetermined distance value, and P is a predetermined resolution value. M is the central angle θ1 corresponding to the sensing element 22. P = K / 2n, where K is the central angle θ2 corresponding to the distance between the center points of two adjacent Hall sensors 3. The central angle corresponding to the minimum distance between the n-th sensing element 22 and the first sensing element 22 is greater than M+P. This allows the controller 4 to easily identify the position of the first sensing element 22.

[0018] With the above configuration, regarding the angle of the Hall sensors 3, the encoding gear 2 is defined to rotate clockwise as shown in Figure 4, and clockwise rotation is defined as the front end or front side, while the reverse direction is defined as the rear end or rear side. When the angle difference between the rear end edge of the first sensing unit 22 in Figure 4 and the rear side edge of the nearest Hall sensor 3 is clockwise plus E degrees, the center angle corresponding to the (1+3h)th Hall sensor 3 rear side edge, measured from the rear side edge of the first sensing unit 22, is E+h*P degrees. Thus, the sensing change of the (1+h)th sensing unit 22 will appear h*P degrees earlier than that of the first sensing unit 22.

[0019] Using this embodiment as an example, 15 Hall sensors 3 are provided, and the number of sensing units 22 is n=4. Therefore, the central angle θ2 corresponding to the distance between the center points of two adjacent Hall sensors 3 is K=360 / 15=24 (degrees). The predetermined resolution value P=K / 2n=24 / (2*4)=3 (degrees). The central angle θ1 corresponding to the sensing unit 22 is M=θ2*3 / 2=36 (degrees). h=natural numbers from 1 to 3, and the central angle corresponding to the distance between the h-th sensing unit 22 and the (h+1)-th sensing unit 22 is M+P=36+3=39 (degrees). The central angle corresponding to the minimum distance between the fourth sensing unit 224 and the first sensing unit 221 (represented by θ4 in Figure 4) is greater than 39 (degrees). With the above configuration, regarding the angle of these Hall sensors 3, when the rear edge of the first sensing unit 221 is aligned with the rear edge of the Hall sensor 3 above it in Figure 4 (E=0), the center angle corresponding to the fourth (1+3h=4) rear edge of the Hall sensor 3, counted from the rear edge of the first sensing unit 221, for the second sensing unit 222 (h=1), is 3 degrees (h*P=3). That is, the rear edge of the second sensing unit 222 is located at an angle 3 degrees clockwise from the rear edge of the fourth Hall sensor 3. Similarly, the center angle corresponding to the seventh (1+3h=7) rear edge of the Hall sensor 3, counted from the rear edge of the first sensing unit 221, for the third sensing unit 223 (h=2), is 6 degrees (h*P=6). The fourth sensing unit 224 (h=3) is the 10th (1+3h=10) Hall sensor 3 whose center angle is 9 degrees (h*P=9) from the rear edge of the first sensing unit 221.

[0020] Therefore, the distance sensing change of the second sensing unit 222 will be 3 degrees earlier than that of the first sensing unit 221, the third sensing unit 223 will be 6 degrees earlier than that of the first sensing unit 221, and the fourth sensing unit 224 will be 9 degrees earlier than that of the first sensing unit 221.

[0021] The number of Hall sensors 3 exceeds the number of sensing elements 22, their positions correspond to those of the sensing elements 22, and they are arranged at equal angles around the axis L. Each Hall sensor 3 has a sensing element 31 for sensing the movement of the sensing elements 22 and outputting a sensing signal. The central angle θ2 corresponding to the distance between the center points of two adjacent Hall sensors 3 is smaller than the central angle θ1 corresponding to each sensing element 22.

[0022] The controller 4 is connected to the Hall sensors 3, receives the sensing signals, and calculates the rotational position of the coded gear 2 based on the sensing signals. The controller 4 can calculate the rotational position of the coded gear 2 through computation or by looking up a pre-stored position correspondence data table. This position correspondence data relates to the relationship between the sensing signals from the Hall sensors 3 and the rotational position of the coded gear 2. The controller 4 determines the rotational position of the coded gear 2 by looking up the position correspondence data based on the sensing signals. The controller 4 can be, for example, an electronic circuit or device with computing and storage functions such as an MCU or a server.

[0023] The corresponding data for this location is shown in Tables 1 and 2, where Hall 1 to Hall 15 represent 15 Hall sensors 3. Furthermore, A, B, C, and D represent the sensing unit 22 that is sensed at this time as the first sensing unit 221, the second sensing unit 222, the third sensing unit 223, and the fourth sensing unit 224, respectively.

[0024] Tables 1 and 2 only list the changes in the sensing signal corresponding to each Hall sensor 3 when the angle is 0 to 69 degrees. Those skilled in the art can deduce the extended details for the angle of 72 to 360 degrees based on Tables 1 and 2 and the above description, so they will not be explained further. Status number angle Hall 1 Hall 2 Hall 3 Hall 4 Hall 5 Hall 6 Hall 7 Hall 8 1 0 A B C 2 3 A B C 3 6 A B C C 4 9 A B B C C 5 12 A A B B C C 6 15 A A B B C C 7 18 A A B B C 8 21 A A B C 9 24 A B C 10 27 A B C 11 30 A B C 12 33 A B B C 13 36 A A B B C 14 39 A A B B C 15 42 A A B B 16 45 A A B 17 48 A B 18 51 A B 19 54 A B 20 57 A B B 21 60 A A B B 22 [[ID=8)) C]] 63 A A B B 23 66 A A B B 态编号 69 A A B Table 1 Status Number Angle Hall 9 Hall 10 Hall 11 Hall 12 Hall 13 It should be noted that there seems to be an error in the original text where "8)) C" is present. It's not clear what this is supposed to be. This translation is done based on the best understanding of the text with this ambiguity. Hall 14 Hall 15 1 0 D 2 3 D D 3 6 D D 4 9 D D 5 12 D D 6 15 D 7 18 D 8 21 D 9 24 D 10 27 D D 11 30 C D D 12 33 C D D 13 36 C D D 14 39 C D 15 42 C D 16 45 C D 17 48 C D 18 51 C D D 19 54 C C D D 20 57 C C D D twenty one 60 C C D D twenty two 63 C C D twenty three 66 C D twenty four 69 C D Table 2

[0025] Based on the above explanation, the effects of this embodiment are as follows:

[0026] 1. By installing Hall effect sensors 3 at equal angles and using a smaller number of sensing units 22, and setting the center angle θ2 corresponding to the distance between the center points of two adjacent Hall effect sensors 3 to be smaller than the center angle θ1 corresponding to the sensing unit 22, it can be seen from Tables 1 and 2 that the arrangement of the sensing units 22 detected by the Hall effect sensors 3 is different at different angles. Therefore, the controller 4 can determine the current rotational position of the encoder gear 2 based on the arrangement of the sensing units 22, and can further calculate the rotational speed based on the change in position.

[0027] Furthermore, compared to conventional sensing methods using densely packed teeth, this embodiment sets a larger center angle θ1 corresponding to the sensing element 22. Therefore, at the same rotational speed, the rate of change of the sensing element 22 sensed by each Hall sensor 3 in this embodiment is significantly lower than the rate of change sensed conventionally. Thus, the upper limit of rotational speed measurement in this embodiment can be greatly increased to over one million revolutions per minute (RPM). Moreover, by increasing the diameter of the encoding gear 2, allowing its circumference to accommodate more Hall sensors 3 or to accommodate more sensing elements 22, the sensing resolution can be further improved.

[0028] Furthermore, since this embodiment is based on a mechanical structure and does not rely on complex electronic circuits, it is not sensitive to electromagnetic interference. The Hall sensor 3 is also resistant to contaminants such as oil fumes and dust, and unlike optical angle measuring devices, it does not require precise alignment and calibration. Therefore, this embodiment can achieve high-speed, high-precision measurement while also having the advantages of long service life, tolerance for larger installation errors, and no need for complex and time-consuming installation.

[0029] Second, by setting the distance between the last sensing element 22 and the first sensing element 22 to be greater than the distance between the other sensing elements 22, the controller 4 can quickly identify the position of the first sensing element 22.

[0030] Third, by making the center angle θ1 corresponding to each sensing element 22 smaller than the center angle θ3 corresponding to the distance between adjacent sensing elements 22, the rate of change of distance sensed by the Hall sensors 3 can be reduced by increasing the distance between the sensing elements 22, thereby increasing the upper limit of rotational speed measurement.

[0031] In summary, the rotation position detection device of the present invention can indeed achieve the purpose of the present invention.

[0032] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification shall still fall within the scope of the patent of the present invention.

[0033] 2: Encoding Gear 21: Wheel section 22: Sensing Unit 221: First sensing unit 222: Second sensor 223: The third sensing unit 224: Fourth sensor unit 3: Hall sensor 31: Sensing Unit 4: Controller 9: Motor 91: Rotor 92: Shaft 93: Stator 94: Shell 95: Shell Cap L: Axis θ1: The angle of the center of the circle corresponding to the sensing element θ2: The central angle corresponding to the distance between the center points of two adjacent Hall sensors θ3: The central angle corresponding to the distance between two adjacent sensing elements θ4: The central angle corresponding to the minimum distance between the fourth sensing element and the first sensing element.

Claims

1. A rotational position detection device, comprising: an coded gear including a wheel portion and at least one sensing portion disposed on the wheel portion, wherein when the wheel portion rotates about its own axis, the at least one sensing portion rotates about the axis, the at least one sensing portion being made of a magnetically conductive material or a magnetic material; and a plurality of Hall sensors, more numerous than the at least one sensing portion, positioned corresponding to the at least one sensing portion and arranged at equal angles around the axis, each Hall sensor being used to sense the movement of the at least one sensing portion and output a sensing signal, defining a central angle as the central angle corresponding to the circumferential arc length along the axis, wherein the central angle corresponding to the distance between the center points of two adjacent Hall sensors is less than the central angle corresponding to the at least one sensing portion.

2. The rotational position detection device as claimed in claim 1, wherein, The coded gear includes a plurality of sensing elements disposed around the axis on the wheel portion, and each sensing element corresponds to the same center angle.

Images