JPS63110943A - Dc motor - Google Patents

Abstract

PURPOSE:To permit the change of the characteristic of the rotation of a rotor arbitrarily during the rotation of the same, by a method wherein intermediate terminals are provided between the neutral point of the coil of Y-connection and three terminals of the coil while the intermediate terminals are short- circuited in accordance with the rotating number of the rotor. CONSTITUTION:Intermediate terminals 15a-15c are provided between the neutral point of a stator coil of Y-connection and three terminals 13a-13c of the stator coil respectively while thin sheets which sort-circuit the intermediate terminals 15a-15c in accordance with the rotating number of a rotor are provided. The characteristic of a motor may be changed arbitrarily during rotation of the rotor in such a way that the torque of the motor is reduced suddenly when the rotating number of the rotor has arrived at a predetermined rotating number to reduce electric power consumption or the like, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a DC motor having Y-connected coils.

(Prior Art) Conventionally, for example, in a DC motor having a Y-connected stator coil, three ends of the Y-connected coil are each connected to a drive circuit, and a drive current is passed through the coil. This rotated a rotor made of permanent magnets.

Further, the motor characteristics of this DC motor were linear from the time of startup to the no-load rotation speed, as shown in FIGS. 5 and 6.

(Problem to be solved by the invention) However, in the above-mentioned conventional motor, the resistance of the coil is always constant and the motor characteristics are linear from the time of startup to the no-load rotation speed. However, when a certain number of rotations is reached, the motor characteristics cannot be changed, such as the inability to reduce the torque, current, and power consumption when a certain number of revolutions is reached, resulting in various problems.

An object of the present invention is to provide a DC motor whose motor characteristics can be changed during rotation.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides intermediate terminal portions between the midpoint of a Y-connected coil and three tips of the coil. A switching section is provided to short-circuit between these intermediate terminal sections depending on the rotational speed of the rotor.

(Function) When the rotor rotates and reaches a predetermined number of rotations, the switching part contacts the intermediate terminal part, shorting the intermediate terminal parts, and the resistance of the coil changes, so the motor characteristics change while the rotor is rotating. can be changed.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. 1 is a rotor, and this rotor 1 is formed by a rotor yoke 2 made of a magnetic material, and a rotor magnet 3 made of a permanent magnet magnetized in the radial direction inside this rotor yoke 2. A rotating shaft 4 is press-fitted and fixed to the holder. Reference numeral 5 denotes a printed wiring board, and this printed wiring board 5 is provided with a hole 6, into which an outer cylinder 7 is inserted. Also, this outer cylinder 7
A bearing 8 for pivotally supporting the rotating shaft 4 is provided inside the outer cylinder 7, a bearing cover 9 is provided below the outer cylinder 7, and a position corresponding to the rotating shaft 4 is provided on the upper part of the bearing cover 9. A bearing seat 10 is provided. A bobbin 11 houses a stator yoke 12 and is screwed to the outer cylinder 7, and a stator coil 13 is wound around the bobbin 11. Further, this stator coil 13 is Y-connected, and three tips 13a, 13b, and 13c are connected to a drive circuit 14 provided on the printed wiring board 5, respectively. Reference numeral 15 denotes an intermediate terminal group provided between each phase of the stator coil 13, and this intermediate terminal group 15
A total of three intermediate terminal portions 15 are provided, one for each phase.
It is composed of a, 15b, and 15c. Reference numeral 16 denotes a thin plate serving as a switching section provided on the outer periphery of the rotor 1, one end 16a of the thin plate 16 is connected to the outer periphery of the rotor 1, and the other end 16b is freely movable. The other end 16b comes into contact with the intermediate terminal portions 15a, 15b, and 15c when the rotor 1 rotates.

Next, regarding the above configuration, the tip 13a of the stator coil 13,
13b, 13c and the intermediate terminal portions 15a, 15b, 15c corresponding to the tips 13a, 13b, 13c, respectively, where R is the resistance of the stator coil 13, and the respective intermediate terminal portions 15a, 15b.

The resistance of the stator coil 13 between 15c and the midpoint will be explained as r. When a voltage is controlled and applied from the drive circuit 14 to each tip 13a, 13b, 13c of the stator coil 13, the rotor 1 rotates about the rotating shaft 4 and gradually increases its speed. At this time, the thin plate 16 hangs downward and does not contact the intermediate terminal portions 15a, 15b, 15c, so the resistance between each tip 13a, 13b, 13c of the stator coil 13 and the midpoint is R+r. . When the rotation speed of the rotor 1 exceeds a predetermined value, the other end 16b of the thin plate 16, which had been hanging downward, is also urged outward as the speed increases, and finally the intermediate terminal portion 15a.

15b and 15c come into contact. At this time, each intermediate terminal portion 15a, 15b, 15c is short-circuited, so that the tips 13a, 13b of the stator coil 13.

The resistance between 13c and the midpoint is R, which is smaller than when the thin plate 16 does not contact the intermediate terminal portions 15a', 45b, and 15c. Further, the process described above will be explained using the motor characteristics shown in FIG. 3 (torque is plotted on the horizontal axis and rotational speed of the rotor 1 is plotted on the vertical axis). Point A indicates the state immediately after the rotor 1 starts rotating, and as the rotation speed increases, the relationship between torque and rotation speed moves to point B. At point B, the thin plate 16 is connected to each intermediate terminal portion 15a, 15b, 15.
This shows a state in which the motor is in contact with point C, and the motor characteristics change after this point B. Similarly, the motor characteristics (
(The horizontal axis shows the torque and the vertical axis shows the current flowing through the stator coil 13.) As the rotational speed of the rotor 1 increases, the relationship between the torque and the current changes as the rotation speed of the rotor 1 increases.
The thin plate 16 is connected to each intermediate terminal portion 15 from the zero point immediately after the start of rotation.
It changes to point D in contact with a, 15b, and 15c, and D
Motor characteristics change across points.

According to the above embodiment, the Y-connected stator coil 13
and the three tips 13a of this stator coil 13,
13b, 13c, intermediate terminal portions 15a, 15b, 1
5c, and these intermediate terminal portions 15a are arranged according to the rotational speed of the rotor 1.

Since the thin plate 16 that short-circuits between 15b and 15c is provided, for example, when the number of rotations of the rotor 1 reaches a predetermined number of rotations, the torque is suddenly lowered to reduce power consumption, etc., while the rotor l is rotating. Motor characteristics can be changed arbitrarily during the process. Furthermore, since centrifugal force is used to act on the thin plate 16, which is the switching section, there is no need for parts necessary to operate the switching section, and there is no need to increase the number of parts.

Note that the present invention is not limited to the above-mentioned embodiment. For example, when the rotor 1 rotates at a low speed, the thin plate 16 contacts the intermediate terminal portions 15a, 15b, and 15c, and when the rotation speed increases, the thin plate 16 contacts the intermediate terminal portions. If it is arranged to be separated from the portions 15a, 15b, and 15c, an effect opposite to that of the above embodiment can be obtained. Further, the coil may be a rotor coil instead of a stator coil, and it is also possible to provide an intermediate terminal portion between the tip of the coil and the middle of the Y connection.

Furthermore, the switching part does not have to be a thin plate as long as it is actuated by centrifugal force, and even if centrifugal force is not necessarily used, a speed detector may be provided separately to detect the speed and switch. Deformation is possible.

[Effects of the Invention] The present invention provides an intermediate terminal section between the center point of a Y-connected coil and three tips of this coil, and switches to short-circuit between these intermediate terminal sections according to the rotational speed of the rotor. Since this section is provided, the motor characteristics can be changed arbitrarily while the rotor is rotating.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention, with Figure 1 being an overall vertical cross-sectional view, Figure 2 being a coil connection diagram, and Figure 3 being a motor characteristic showing the relationship between torque and rotational speed. 4 are motor characteristic diagrams showing the relationship between torque and current, FIG. 5 is a diagram corresponding to FIG. 3 of the conventional example, and FIG. 6 is a diagram equivalent to FIG. 4 of the conventional example. In the figure, 13 is a stator coil (coil), 13a, 13
b, 13c are tips, 15a, 15b, 15c are intermediate terminal portions, and 16 is a thin plate (switching R). Yukio Yuyama Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. It has a Y-connected coil, and has an intermediate terminal section provided between the center point of the coil and three tips of the coil, and A direct current motor characterized by having a switching part that short-circuits between these intermediate terminal parts according to the switching part. 2. The DC motor according to claim 1, wherein the switching section is actuated by centrifugal force accompanying rotation of the rotor.