DC motor capable of detecting speed

Abstract

The present invention relates to a DC motor including: a rotor; a stator; a commutator having a plurality of terminal units; and a brush electrically connecting a DC power source to the terminal units of the commutator, wherein the DC motor may include: a detection unit electrically connected to a specific terminal unit of the commutator; and a detection brush coming in contact with the outside of the detection unit to allow an external microcomputer to detect an electrical signal of the DC power source.

Description

DC motor with speed detection

[0001] The present invention relates to a DC motor capable of speed detection, and more specifically, to a DC motor capable of speed detection without using a separate speed detection sensor.

[0002] In general, a method of mounting a speed detection device including a magnetic sensor or an optical sensor on the outside of a DC motor is used to detect the speed of a brush-type DC motor.

[0003] Specifically, a method is used in which a magnet is mounted on the outside of the motor and a magnetic sensor detects changes in the magnetic field according to rotation, or a method is used in which the rotation speed is detected using an optical sensor including a rotating plate with holes formed therein and a light emitting unit and a light receiving unit.

[0004] These conventional methods required additional mounting on the outside of the DC motor, which increased manufacturing costs and the process cost due to the additional assembly process.

[0005] Additionally, there was a disadvantage in that the load on the motor increased because additional components such as magnets were installed on the rotating shaft of the DC motor.

[0006]

[0007] The problem that the present invention seeks to solve in consideration of the problems of the prior art as described above is to provide a DC motor capable of detecting the speed of the DC motor without adding a separate speed detection device to the outside of the DC motor.

[0008] The DC motor of the present invention comprises a rotor, a stator, a commutator having a plurality of terminals, and a brush for electrically connecting a DC power source to the terminals of the commutator, and may include a detection unit electrically connected to a specific terminal of the commutator, and a detection brush that contacts the outside of the detection unit so that an electrical signal of the DC power source can be detected by an external microcomputer.

[0009] In an embodiment of the present invention, the detection unit may include a detection terminal unit that is positioned at a position corresponding to a specific terminal unit of the commutator with the same shape.

[0010] In an embodiment of the present invention, the brush includes a pair of brush portions arranged parallel to each other, and the detection brush may be arranged in a vertically intersecting direction spaced apart from the brush portions.

[0011] In an embodiment of the present invention, the brush includes a pair of brush portions arranged parallel to each other, and the detection brush can be arranged in a parallel direction and spaced apart from the brush portions.

[0012] In an embodiment of the present invention, the microcomputer can detect an electrical signal in a rotation angle range of the rotor in which a positive potential of a direct current power source is applied to the specific terminal portion of the commutator and the detection terminal portion comes into contact with the detection brush.

[0013] In an embodiment of the present invention, the terminal portions of the commutator are provided in multiple numbers with an insulator therebetween so as to be mutually insulated, a specific terminal portion of the commutator has an inner angle of 360 degrees divided by the number of terminal portions including an insulator on one side, and the detection terminal portion may have the same inner angle as the specific terminal portion.

[0014] In an embodiment of the present invention, the detection unit may be a split rotational shaft that is positioned spaced apart from the rotational axis of the rotor and is fixed by fitting a portion of the inner diameter of the commutator.

[0015] In an embodiment of the present invention, the split rotation axis may be connected to a specific terminal of the commutator as a resistor.

[0016]

[0017] The present invention uses a detection unit having a contact electrically connected to a specific contact of a commutator provided inside a DC motor, and includes a detection brush that outputs the electrical detection result of the detection unit to the outside, thereby enabling speed detection without adding a separate speed detection device to the outside of the DC motor, thereby reducing the manufacturing cost of a DC motor capable of speed detection and reducing the number of manufacturing process steps.

[0018] In addition, the present invention has the effect of improving safety and reliability of speed detection by arranging a means for speed detection within the housing of a DC motor, compared to a conventional structure using an external additional device.

[0019]

[0020] Figure 1 is a schematic diagram of a DC motor according to a preferred embodiment of the present invention.

[0021] Figure 2 is a detailed configuration diagram of the main parts of the present invention.

[0022] Figure 3 is a schematic plan view of a commutator and a detector.

[0023] Figure 4 is an explanatory diagram illustrating the forward rotation of the present invention.

[0024] Figure 5 is an explanatory diagram explaining the reverse rotation of the present invention.

[0025] Figure 6 is a configuration diagram of a DC motor according to another embodiment of the present invention.

[0026] Fig. 7 is a cross-sectional view of a portion of Fig. 6.

[0027] Figure 8 is a configuration diagram of a DC motor according to another embodiment of the present invention.

[0028] - Explanation of symbols -

[0029] 10: Stator 20: Rotor

[0030] 30: Commutator 31: First terminal

[0031] 32: Second terminal section 33: Third terminal section

[0032] 40: Brush 41: First brush section

[0033] 42: Second brush section 50: Detection section

[0034] 51: Detection terminal 60: Detection brush

[0035] 70: Frontline

[0036]

[0037]

[0038] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and can be modified in various ways. However, the description of the present embodiments is provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the present invention of the scope of the invention. In the accompanying drawings, components are illustrated in an enlarged size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

[0039] Terms such as "first" and "second" may be used to describe various components, but the components should not be limited by these terms. These terms may only be used to distinguish one component from another. For example, without departing from the scope of the present invention, a "first component" may be referred to as a "second component," and similarly, a "second component" may also be referred to as a "first component." Furthermore, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms used in the embodiments of the present invention may be interpreted as having meanings commonly known to those of ordinary skill in the art, unless otherwise defined.

[0040] Hereinafter, a DC motor according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0041] Figure 1 is a schematic diagram of a DC motor according to a preferred embodiment of the present invention.

[0042] Referring to FIG. 1, the present invention may further include a detection unit (50) that is coupled to the rotational axis (21) of the rotor (20) in a DC motor including a stator (10), a rotor (20), a commutator (30), and a brush (40) and includes a terminal portion electrically connected to one terminal portion of the commutator (30), and a detection brush (60) that outputs an electrical detection result detected by the detection unit (50) to the outside.

[0043] Hereinafter, the configuration and operation of the DC motor of the present invention configured as described above will be described in more detail.

[0044] First, the DC motor of the present invention forms a magnetic field in the stator (10), and when a DC voltage is supplied to the commutator (30) through the brush (40), when a current is supplied to the coil of the rotor (20) connected to each terminal of the commutator (30), an electromotive force is generated according to Fleming's left-hand rule, causing the rotor (20) to rotate.

[0045] For this purpose, the stator (10) is configured to include a field magnet (11) and a field coil (not shown in the drawing), and the rotor (20) includes a coil (23) wound around an iron core (22) and a rotation shaft (21).

[0046] This configuration can be changed in shape or form as needed, and in the drawing, a pair of field magnets (11) are shown, and the coils (23) of the rotor (20) are also shown as a pair of structures, but this is for convenience of explanation, and for more stable operation, it is preferable to use at least three field magnets (11) and coils (23).

[0047] The above commutator (30) is fixedly connected to the rotation shaft (21) and rotates together with the rotation shaft (21).

[0048] The above commutator (30) includes a plurality of terminal portions that are mutually insulated, and each terminal portion is electrically connected to each coil (23) of the rotor (20).

[0049] As is known, the brush (40) is installed in a fixed state and is in contact with the terminal of the commutator (30), and as the commutator (30) rotates, the terminal that is in contact with the brush (40) is changed so that the electromotive force is maintained and the rotation direction is kept constant according to the direction of current supply, thereby rotating the rotor (20).

[0050] Fig. 2 is a schematic diagram of the main parts of the DC motor of the present invention, and Fig. 3 is a planar schematic diagram of the commutator and detector.

[0051] Referring to FIGS. 2 and 3, the commutator of the present invention may include at least two terminal portions, and for the purpose of explaining the present invention, a structure having three terminal portions will be described.

[0052] The commutator (30) is a conductor and may include a first terminal portion (31), a second terminal portion (32), and a third terminal portion (33), which are each electrically separated. The shape of the commutator (30) is a cylindrical structure, and the first to third terminal portions (31, 32, 33) may be positioned in a divided manner on the side that contacts the brush (40).

[0053] The first to third terminal sections (31, 32, 33) are each formed with the same area. When three terminal sections are used, they can be divided into a shape with a central angle of 120 degrees, including an insulator (not shown in the drawing), as shown in Fig. 3.

[0054] The coils of the rotor (20) are individually connected to each of the first to third terminals (31, 32, 33).

[0055] The configuration examples of these commutators (30) are illustrative of embodiments and may include various known or predictable structures.

[0056] The brush (40) includes a pair of brush parts to which a direct current voltage is connected. For example, it may be composed of a first brush part (41) connected to the positive pole of a direct current power source such as a battery when rotating in the forward direction, and a second brush part (42) connected to the negative pole.

[0057] When rotating in reverse, the negative pole of the DC power supply is connected to the first brush unit (41), and the positive pole is connected to the second brush unit (42).

[0058] The detection unit (50) is fixedly connected to the rotation axis (21) and rotates together with the rotation axis (21).

[0059] The detection unit (50) includes a detection terminal unit (51) connected to the first terminal unit (31) of the commutator (30) through a wire (70). The detection terminal unit (51) is single, and the detection unit (50) excluding the detection terminal unit (51) is made of an insulator.

[0060] The detection terminal portion (51) can be positioned at the same position with respect to the first terminal portion (31) with respect to the rotation axis (21).

[0061] As previously explained, the first terminal portion (31) can be formed on a fan-shaped circumference with a central angle of 120 degrees (including the insulator between the second terminal portions (32)), and the detection terminal portion (51) can also be formed in the same manner.

[0062] The above detection unit (50) may be a commutator having one terminal unit.

[0063] A detection brush (60) is in contact with the above detection unit (50). The detection brush (60) is fixed so as not to rotate, and while the first terminal unit (31) is in contact with the first brush unit (41), the potential of the positive electrode side of the DC power supply is applied to the detection terminal unit (51) through the wire (70), and the potential at this time is detected.

[0064] The detection brush (60) in contact with the above detection terminal (51) is electrically connected to the detection terminal of the processor of a microcomputer (not shown in the drawing), and the microcomputer can detect an electrical signal.

[0065] At this time, resistance, etc. may be added as needed.

[0066] Therefore, the rotational speed of the rotor (20) can be detected using the detection cycle and time of the electrical signal through the detection terminal (51).

[0067] The operation of the present invention will be described in more specific examples as follows.

[0068] Figure 4 is an explanatory diagram explaining the operation of the present invention when driving in the forward direction.

[0069] Referring to Fig. 4, the state in which the commutator (30) rotates in the forward direction (clockwise) together with the rotation axis (21) is illustrated at characteristic intervals, and the position of the detection terminal (51) is also illustrated at this time.

[0070] First, at 0 degrees, which is the initial state, the first terminal portion (31) of the commutator (30) may be in contact with the first brush portion (41) connected to the positive pole of the DC power source, and the second terminal portion (32) may be in contact with the second brush portion (42) connected to the negative pole of the DC power source. At this time, current flows in the rotor coil connected to the first terminal portion (31) and the second terminal portion (32), and the rotor (20) rotates under the influence of the magnetic field of the stator (10).

[0071] At this time, the detection terminal (51) of the detection unit (50) is electrically connected to the first terminal (31) through a wire (70) and is in contact with the detection brush (60), and thus, an electrical signal is detected by the microcomputer.

[0072] The above first brush part (41) and the detection brush (60) are installed in an orthogonal direction.

[0073] A positive potential of a positive electrode is applied to the first terminal portion (31) in contact with the first brush portion (41) and the detection terminal portion (51) connected by a wire (70), and this can be detected externally through the detection brush (60) in contact with the detection terminal portion (51).

[0074] The electrical signal at this time may be voltage or current, and by using the analog input terminal of the microcomputer, the electrical signal of the detection brush (60) can be detected without using a separate digital conversion means.

[0075] Current flows through the rotor coil, which is connected at both ends to the first terminal (31) and the second terminal (32), and the rotor (20) rotates under the influence of the magnetic field of the stator (10).

[0076] Even when the rotor (20) is rotated less than 30 degrees, the 0 degree state described above is maintained, and at this time, detection can be performed through the detection brush (60). If the detection brush (60) is arranged parallel to the first brush unit (41), the microcomputer can detect an electrical signal in a range from 0 degrees or more to less than 120 degrees in the positive direction when the rotation angle of the rotor (20) is less than 120 degrees.

[0077] In the present invention, in order to enable the detection of an electrical signal of a microcomputer to occur in a relatively short period, the detection brush (60) is arranged to be vertically crossed while being spaced apart from the first brush unit (41).

[0078] When the rotation angle of the rotor (20) is 30 degrees or less, the detection terminal part (51) of the detection part (50) is maintained in contact with the detection brush (60), and at this time, the first terminal part (31) of the commutator (30) is also connected to the first brush part (41), so the microcomputer can detect an electrical signal.

[0079] When the rotation angle of the rotor (20) is 30 degrees or more, the detection terminal portion (51) of the detection unit (50) is released from contact with the detection brush (60). When the rotation angle is 30 degrees or more and less than 120 degrees, the first terminal portion (31) is in contact with the first brush portion (41), but the detection terminal portion (51) of the detection unit (50) is not in contact with the detection brush (60), so detection of an electrical signal becomes impossible.

[0080] The angle less than 120 degrees above is exactly the angle of the inner angle of the insulator between the first terminal (31) and the second terminal (32) minus 120 degrees.

[0081] In a section where the rotation angle of the rotor (20) is 120 degrees or more, the first terminal portion (31) is also released from the first brush portion (41), and therefore, no electrical signal is detected regardless of the position of the detection terminal portion (51) of the detection portion (50).

[0082] In a section where the rotation angle of the rotor (20) is greater than or equal to 120 degrees and less than 180 degrees, the second terminal portion (32) and the third terminal portion (33) are in contact with the first brush portion (41) and the second brush portion (42), respectively, and current flows to the coils of the rotor brushes connected to the second terminal portion (32) and the third terminal portion (33), so that the rotor (20) can continue to rotate in the forward direction.

[0083] In a section of 180 degrees or more, the first terminal part (31) comes into contact with the second brush part (42), and the second terminal part (32) comes into contact with the first brush part (41).

[0084] Even if the negative electrode of the DC power source comes into contact with the first terminal (31), no electrical signal is applied to the detection terminal (51) of the detection unit (50), and a state in which no electrical signal is detected through the detection brush (60) is maintained.

[0085] When the rotation angle of the rotor (20) is less than 240 degrees, the above state is maintained, and when it is more than 240 degrees, the third terminal part (33) is in contact with the first brush part (41), and the first terminal part (31) is in contact with the second brush part (42).

[0086] Afterwards, when rotating 360 degrees, the state becomes the same as the initial state described above, so detection of an electrical signal becomes possible through the detection brush (60).

[0087] Accordingly, the number of rotations can be detected based on the electrical signal detected through the detection terminal (51) and detection brush (60) of the detection unit (50), and the rotation speed can be detected using time.

[0088] Figure 5 is an explanatory diagram explaining the operation of the present invention when driving in the forward direction.

[0089] Referring to Fig. 5, the state in which the commutator (30) rotates in the reverse direction (counterclockwise) together with the rotation axis (21) is illustrated at characteristic intervals, and the position of the detection terminal (51) is also illustrated at this time.

[0090] That is, unlike the example of FIG. 4 shown above, the first brush unit (41) is structured such that the negative pole of the DC power source is connected, and the second brush unit (42) is structured such that the positive pole of the DC power source is connected, so that the current from the DC power source flows in the opposite direction.

[0091] First, at 0 degrees, which is the initial state, the first terminal portion (31) of the commutator (30) may be in contact with the first brush portion (41) connected to the negative pole of the DC power source, and the second terminal portion (32) may be in contact with the second brush portion (42) connected to the positive pole of the DC power source. At this time, current flows in the rotor coil connected to the first terminal portion (31) and the second terminal portion (32), and the rotor (20) rotates under the influence of the magnetic field of the stator (10).

[0092] At this time, the detection terminal (51) of the detection unit (50) is electrically connected to the first terminal (31) through a wire (70), but a negative potential is connected to the first terminal (31), so no electrical signal is detected by the microcomputer.

[0093] When reverse rotation occurs and the rotor (20) rotates more than 60 degrees (indicated as -60 degrees) in the reverse direction, the first terminal portion (31) comes into contact with the second brush portion (42), and thus is connected to the positive potential of a direct current power source (battery, etc.), which is provided to the detection terminal portion (51) of the detection portion (50) through the wire (70), and can be detected by the microcomputer through the detection brush (60) in contact with the detection terminal portion (51).

[0094] When the rotor (20) rotates in the reverse direction in the range of 60 to 90 degrees, the above detection state is maintained, and when the rotation exceeds 90 degrees (less than -90 degrees), the detection terminal (51) is released from contact with the detection brush (60), so that signal detection is not performed.

[0095] When the rotor (20) is rotated in the reverse direction by more than 180 degrees and less than 240 degrees, the third terminal part (33) comes into contact with the second brush part (42), and the second terminal part (32) comes into contact with the first brush part (41), so that current flows to the rotor coil connected to the third terminal part (33) and the second terminal part (32), and reverse rotation is maintained.

[0096] At this time, the first terminal part (31) is out of contact with the second brush part (42), and no electrical signal is detected by the microcomputer.

[0097] After the -420 degree rotation state is reached, the microcomputer can detect the electric signal again, just like the reverse 60 degree rotation state described above.

[0098] Accordingly, the number of rotations can be detected based on the electrical signal detected through the detection terminal (51) and detection brush (60) of the detection unit (50), and the rotation speed can be detected using time.

[0099] Although the housing of the DC motor of the present invention is omitted in the drawings and description, the structure of the present invention including the detection unit (50) and detection brush (60) described above is accommodated within the housing, and there is no structure exposed to the outside of the housing, so that a more stable structure can be provided.

[0100] This has the characteristic of preventing damage to parts caused by external interference.

[0101] FIG. 6 is a schematic diagram of a DC motor according to another embodiment of the present invention, and FIG. 7 is a cross-sectional diagram of a portion of FIG. 6.

[0102] Referring to FIGS. 6 and 7, respectively, a DC motor according to another embodiment of the present invention can be provided with a structure in which the detection unit (50) described above is omitted.

[0103] In another embodiment of the present invention, a separate detection unit (50) is not used, but a split rotation shaft (21a) is used as the detection unit.

[0104] That is, unlike the structure of a general DC motor, the present invention uses a split rotation shaft (21a) that is separated from the rotation shaft (21) of the rotor (20) and is fixedly placed in a state separated from the rotation shaft (21) by a commutator (30).

[0105] The commutator (30) is fixed by fitting a part of the rotation axis (21) and a part of the split rotation axis (21a) into the inner diameter of the insulating portion.

[0106] A through hole is formed in the lower insulating portion of the first terminal portion (31) of the commutator (30), and a wire (70) electrically connects the first terminal portion (31) and the split rotation shaft (21a) through the through hole.

[0107] Accordingly, when the first brush portion (41) is in contact with the first terminal portion (31), the potential of the positive electrode of the DC power source is also supplied to the split rotation shaft (21a), and this is detected by the detection brush (60) in contact with the split rotation shaft (21a), and thus the rotation speed can be detected externally.

[0108] An example of connecting the first terminal (31) and the split rotation shaft (21a) with a wire (70) was described above, but it can also be electrically connected using a resistor.

[0109] Figure 8 is a configuration diagram of a DC motor according to another embodiment of the present invention.

[0110] Referring to Fig. 8, there is an example of a structure that can be implemented without using wires in the structure described above with reference to Fig. 1.

[0111] Specifically, a structure is proposed in which the body of the detection unit (50) and the body of the rectifier (30) are commonly used, but the first terminal unit (31) is expanded so that it can be used as the detection terminal unit (51) in the previous example.

[0112] By this structure, the present invention has the feature of simplifying the configuration and reducing the size.

[0113] The first terminal portion (31) extended to the above detection terminal portion (51) can detect whether a positive power source is supplied by the detection brush (60), and since the actual operating principle is the same as the example described above, except for some differences in structure, a detailed description will be omitted.

[0114] While the embodiments of the present invention have been described above, they are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Therefore, the true scope of technical protection of the present invention should be defined by the following claims.

[0115] The present invention can easily detect the speed of a DC motor by simply changing the structure using the laws of nature, and thus has industrial applicability.

Claims

1. A DC motor including a rotor, a stator, a commutator having a plurality of terminals, and a brush for electrically connecting a DC power source to the terminals of the commutator, a detection unit electrically connected to a specific terminal of the above commutator; and A DC motor including a detection brush that contacts the outside of the detection unit and enables an electrical signal of a DC power source to be detected by an external microcomputer.

2. In paragraph 1, The above detection unit, A DC motor including a detection terminal portion arranged at a position corresponding to a specific terminal portion of the above commutator with the same shape.

3. In paragraph 2, The above brush comprises a pair of brush parts arranged parallel to each other, A DC motor characterized in that the detection brush is arranged in a vertical cross direction and spaced apart from the brush portion.

4. In paragraph 2, The above brush comprises a pair of brush parts arranged parallel to each other, A DC motor characterized in that the detection brush is arranged in a parallel direction and spaced apart from the brush portion.

5. In paragraph 3 or 4, The above microcomputer, A DC motor characterized in that a positive potential of a DC power source is applied to the specific terminal portion of the commutator, and an electrical signal is detected in a rotation angle range of the rotor in which the detection terminal portion comes into contact with the detection brush.

6. In paragraph 3 or 4, The terminals of the above commutator are provided in multiple numbers with an insulator between them so as to be mutually insulated, The specific terminal portion of the above commutator has an inner angle of 360 degrees divided by the number of terminal portions, including an insulator on one side, and A DC motor characterized in that the above detection terminal part has the same internal angle as a specific terminal part.

7. In paragraph 1, The above detection unit, A DC motor characterized by a split rotational axis that is positioned on the same axis as the rotational axis of the rotor and is fixed by fitting a portion of the inner diameter of the commutator.

8. In paragraph 7, The above split rotation axis is, A DC motor characterized in that a specific terminal of the commutator is connected by a resistor.

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