JPS60204243A - Dc rotary electric machine - Google Patents

Abstract

PURPOSE:To obtain preferable characteristic even at low and high voltage time by using a combination of metal brushes and carbon brushes, thereby associating the advantages of the both. CONSTITUTION:Metal brushes 2a, 2b and carbon brushes 3a, 3b are combined in contact on a commutator 1 to form positive and negative brushes. A connection switching unit to the brushes is separately provided, the brushes 2 having preferable characteristics at a low voltage time may be used at the low voltage driving time, and the brushes 3 having preferable characteristic at a high voltage time may be used at the high voltage driving time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC rotating electric machine equipped with a commutator and a brush.

Conventionally, low-voltage, small-output DC motors have generally used brushes made of metal contact materials (hereinafter referred to as stable) with low contact resistance.
Metal brushes (called metal brushes) are used, but they have the disadvantage of short lifespan. In addition, for high voltage, large output DC motors,
A carbonaceous contact material (hereinafter referred to as a carbon brush) is used as the brush, which has a longer lifespan than a metal brush, but it has the drawback of high contact resistance and instability.

Therefore, for example, as in the direct skewer drive type motor of a video recorder (hereinafter referred to as VTR), a relatively low voltage of 1 to 2 V to several 10 V can be applied to achieve extremely low speeds (several 1 Orpm). High speed (3o00rp■
For devices that are driven in the above range, it is extremely difficult to achieve both stability of operation and durability by using a brush as a contact member made of a single material.

The present invention has been proposed in view of the above, and an object of the present invention is to obtain a DC rotating electric machine with fewer inconveniences caused by brushes.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a two-pole motor. In this 2-pole motor, 5
The feed point is located 180' opposite the commutator 1, which consists of two segments.

The arrangement of the metal brushes 2a, 2b and the carbon brushes 3a, 3b is as shown in the figure. That is, a metal brush and a carbon brush are used in combination as a positive (plus) side splint and a negative (minus) side splint. In this case, a selector switch (not shown)
Using metal brushes 2a, 2b and carbon brushes 3a, 3b
Although it is possible to switch the power supply to the metal brush and the carbon brush, it is also possible to always electrically connect the metal brush and the carbon brush in parallel to supply power.

Figure 2.3 is an example of a multi-pole motor, as shown in Figure 4, the number of poles is 4, the number of coils is 5, and the number of commutator segments is r.
There is one from lOJ. Five coils 41-45 are connected as shown, and ten segments 11-I
Io is short-circuited at 180° opposing positions. In this case, metal brush 2a and carbon brush 3a, metal brush 2b and carbon brush 3a,
b are in contact with commutator segments of the same potential, but in reality, for example, when the metal brush 2a is in contact with the commutator segment 17, the moment when the carbon brush 3a contacts the commutator segment 13 is At this moment, the coil 42 becomes a closed coil and generates a large spark. Therefore, metal brush 2a and carbon brush 3a, metal brush 2b and carbon brush 3
b cannot be kept connected all the time, so they are switched between each other by interlocking changeover switches 5a and 5b. This switching operation may be performed using the brush switching terminals 16 led from each brush of the motor body in conjunction with the mode switching operation of the main unit (VTR).

As described above, the present invention uses a metal brush and a carbon brush in combination, so when the power supply voltage is relatively low (1 to 2 V), it is possible to use the metal brush with low contact resistance and good conductivity. Current flows and the power supply voltage is high (several tons)
In the case of OV), current also flows through the carbon brush, which has excellent durability against rectifying sparks. As a result, there are no inconveniences caused by brushes, such as short service life when using only metal brushes, or unstable operation due to high contact resistance when using only carbon brushes, and there are no inconveniences caused by brushes, such as the short lifespan when using only metal brushes, and the unstable operation due to high contact resistance when using only carbon brushes.
Thus, it is possible to obtain a DC rotating electric machine that can smoothly control speed changes up to 0,000 rpm.

In addition, when the multi-polar motor is constructed flat, as shown in Figure 3.5, metal brushes 2a, 2b and carbon brushes 3a, 3
b, in the same plane perpendicular to the rotor axis 6, with their positions shifted in the circumferential direction of the rotor axis, it is possible to increase the output power that enables high-voltage driving without increasing the rotor axial dimension. There are effects such as being able to obtain a rotating electric machine.

In FIG. 5, 7 is a motor case, and a bearing 8 for supporting the rotor shaft 6 is attached to the center of the motor case.

9 is a field magnet provided on the inner surface of the motor case 7;
is a cylindrical body attached to the rotor shaft 6, and a large-diameter cylindrical portion at one end of the cylindrical body is placed over the outside of the bearing 8. Reference numeral 11 denotes an armature core laminated and fixed to the cylindrical body lO, 12 a spark extinguishing element, 13 a motor end cover that can be attached to and removed from the opening of the motor case 7, and 14 a motor end cover 13 that receives the end face of the rotor shaft 6. 15 is a rocker plate provided on the inner surface of the motor end cover 13 to which a brush and a brush switching terminal are attached. Brushes 2a, 2b, 3a, 3b are rocker plates 15
A printed pattern (not shown) provided on the switching terminal 16-
1 to 16-4.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the relationship between the commutator and brush in a two-pole motor showing an embodiment of the present invention, and FIG. 2 shows the relationship between the commutator and brush in a multi-polar motor showing another embodiment. The front view, FIG. 3 is a perspective view showing the arrangement of the brushes, and FIG.
The figure is an armature circuit connection diagram, and FIG. 5 is a partially cutaway sectional view showing an example of the DC rotating electrical machine of the present invention. 1 is a commutator, 2a and 2b are metal brushes, 3a and 3b are carbon brushes, 4. -45 are armature coils, 5a and 5b are interlocking changeover switches, 6 is a rotor shaft, and 16-0 to 16-4 are changeover terminals. Patent applicant: Canon Co., Ltd. Agent Fuku 1) Kan1-j

Claims (2)

[Claims] (1) A DC rotating electric machine characterized in that a metal contact member and a carbon contact member are used in combination as a positive brush and a negative brush. (2) The metallic contact member brush and the carbonaceous contact member brush are connected to and separated from a power source so that the metallic contact member brush is used as a low voltage drive brush and the carbonaceous contact member is used as a high voltage drive brush. A DC rotating electric machine according to claim (1), comprising a brush switching terminal.