JPH01198246A - Rectifier for small-sized motor - Google Patents

Abstract

PURPOSE:To conduct smooth rectification, and to reduce noises and vibrations by sliding a brush with a sliding section formed of the bundle of metallic fine wires arranged in one direction on a sliding surface formed of a metallic sintered body containing carbon. CONSTITUTION:A bundle 8 of tens of elastic metallic fibers having diameters of approximately 100-200mum are held between a pectinate type holding plate 7. The free ends of the fiber bundles 8 are lengthened with the increase of the diameters of the fibers, a brush 8a is formed, and other ends are welded and fixed. A sliding surface brought into contact with the fiber bundles 8 for a commutator 9 fastened to a shaft 10 is formed of the sintered body of a metal and carbon. Accordingly, the brush 8a and the commutator 9 are brought into contact excellently, thus reducing mechanical and electrical noises.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rectifying device for small DC motors used in many applications such as audio equipment and precision equipment.

2. Description of the Related Art Although not limited to small motors, generally in a commutator motor that supplies current to a rotor winding through brushes, a commutator (commutator) connected to the rotor winding and brushes are connected to the rotor winding. An important issue is to stabilize the contact state between the brush and the commutator, but the contact state between the brush and the commutator becomes unstable due to the unevenness of the commutator surface, especially the vibration of the brush when rubbing the space between the segments. , an undesired arc occurs.

Conventionally, in order to stabilize the state of contact between the commutator and the brush, a brush structure as shown in FIG. 4, for example, has been adopted to quickly dampen the brush vibrations that occur. That is, a vibration damping material 2 made of rubber or a non-rubber sheet is attached with an adhesive 3 to a thin plate 1 of an elastic conductive material, for example, phosphor bronze, in the longitudinal direction.

On the other hand, since a multi-contact slider is good for stabilizing the contact state, a multi-contact contactor made by photo-etching,
Carbon fiber brushes, metal-coated carbon fiber brushes (Fig. 5), and the like are known.

Problems to be Solved by the Invention However, it is not possible to completely eliminate the vibration of the brush with the above-described structure in which a vibration isolating material is attached, and there is a desire to further reduce the remaining electrical and mechanical noise. cannot respond to Further, there is a problem in that the adhesive is affected by environmental conditions such as temperature and humidity, and the adhesive strength changes under high temperature and high humidity, and low temperature and humidity, which in turn leads to a decrease in the vibration damping properties of the brush.

On the other hand, regarding multi-contact sliders that can ensure contact stability, there were problems such as poor photoetching processability of precious metals, and carbon fiber brushes having soft carbon fibers (easily broken). As for the method of holding the other end on the side that is not a moving part, methods such as heat-pressing, fixing with a contact agent, and caulking have been considered, but all of these methods have been difficult in terms of mass production, conductivity, and fiber strength. .

The present invention aims to solve these problems,
The present invention provides a rectifying device for a small motor that has high vibration damping properties, strong strength, and excellent mass productivity.

Means for Solving the Problems In order to solve the above problems, the present invention provides a brush having a sliding part made of a bundle of metal wires aligned in one direction, and a brush with a sliding part made of a sintered body of metal containing carbon. The commutator has a sliding surface that comes into contact with the moving parts. Further, the free end of the metal wire is indicated by a comb-shaped holding plate having a plurality of slits.

Function: In the present invention, by forming the sliding portion into a bundle of a large number of metal wires, the contact points with the commutator are multiplied, and the contact state is stabilized.

In other words, this leads to a reduction in electrical and mechanical noise.

In addition, conventional multi-contact sliders had problems with materials, mass production, etc., but the brush device of the present invention, which is made of elastic metal fibers, has strong material and The other end can be easily held by laser welding. Furthermore, when a bundle of metal fibers having elasticity as shown in the present invention is used as a cantilever beam, the sliding part and the tip tend to be dispersed and randomly oriented due to the pressure against the commutator. Easy to hold the tip of the metal bundle (prevents deformation of the brush).

In this way, the other end of the non-sliding part can be held using the simple method of laser welding, making it possible to automate the process of loading conductive metal fibers, cutting them to predetermined dimensions, and welding them to the terminal plate. There is no need to attach anti-vibration material to the surface, leading to improved productivity.

Further, since no adhesive or the like is used, the influence of environmental conditions on contact stability is small.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a block diagram of a brush device of the present invention.

FIG. 2 shows a state in which the brush is in contact with the sliding portion of the commutator 9 in a pressed state.

Figure 3 shows the measurement results of the rectification waveform and mechanical noise after 300 hours with a small motor using a fiber brush consisting of 30 phosphor bronze wires of φ0.15 and a silver streamer containing 20% carbon. It is something.

In the figure, 8 is an elastic metal fiber (phosphor bronze fiber, beryllium gi4m fiber, etc.) with a diameter of about 100 to 200μ.
A bundle of 20 to 40 pieces is pulled in one direction to form 2 to 3 bundles.
It is a layered fiber bundle. Reference numeral 7 designates a comb-shaped holding plate with a plurality of slits, which has a rigidity that is not affected by the vibrations of rotor rotation and minute vibrations of the vibrator.The slits hold the free end of the fiber bundle 8, and the other end of the fiber bundle The welding is fixed.

These comb-shaped holding plates 7 and fiber bundles 8 constitute a brush 8a. The length of the fiber bundle 8 varies depending on the fiber diameter, and it is necessary to have a culm length with a large diameter in order to provide elasticity.

9 is a commutator whose sliding surface that contacts the fiber bundle 8 is formed of a sintered body of carbon and metal, and 10 is a rotor shaft on which the commutator 9 is provided.

In this way, compared to the case where the sliding portion is a surface, by making the sliding portion a fiber, multiple contact points can be obtained, and the contact area per unit area can be increased. In addition, when scraping the irregularities on the surface of the commutator 9, especially the spaces between the segments, unlike when they are moving as one mass, they are all a collection of independent fibers, so they all jump at the same time. Therefore, the contact state is stabilized without causing a state of non-contact with the commutator 9. That is, the rectifier of the present invention has a better rectified waveform (FIG. 3(a)) than the conventional example. Stabilizing the contact state with the commutator 9 leads to a reduction in electrical and mechanical noise (FIG. 3(b)). This tendency is remarkable because the longer the sliding time becomes, the more unstable the contact state of the conventional brush becomes.

In the conventional fiber brush, the fibers 5 are oriented perpendicular to the sliding direction as shown in FIG. 5, but in the present invention, the fiber bundles 8 are oriented in the same direction as the sliding direction, as shown in FIG. It has become. When soft and inelastic fibers such as carbon fibers are used, if they are oriented in the sliding direction and once they reach a non-contact state, they cannot return to the original contact state. Since the present invention is composed of 20 to 40 bundles of elastic metal fibers,
Even if a non-contact state occurs due to fiber jumping caused by the rotation of the commutator, the original contact state can be restored. Furthermore, if the fiber bundles 8 are pressed against the sliding part in the same direction as the sliding direction, that is, in a cantilevered state, the fiber bundles 8 will be dispersed, making it impossible to form a multilayer. With the structure in which the free ends are maintained, the ';a fiber bundles 8 will not be dispersed even in the suppressed state.

In addition, the brush of the present invention has a laminated structure of two to three layers of metal fiber bundles, and the minute vibrations of each fiber caused when rubbing the irregularities on the commutator surface and the gaps between segments are , the vibration of each fiber causes friction between the fibers and is converted into thermal energy, and the minute vibrations are attenuated (.

Furthermore, the comb-shaped holding plate 7 of the present invention maintains the multilayered structure of the fiber bundle 8 even if minute vibrations occur, so that the friction between the fibers can serve as a vibration isolator.

Therefore, it has good contact stability and has a self-dampening function against vibrations that once occur.

A commutator 9 with which the multilayered metal fiber bundle 8 is in direct contact.
The sliding surface is made of a sintered metal containing 10 to 20% carbon in a highly conductive metal such as silver Ag or fJAcu. The metal fiber bundle 8 is made of elastic metal fibers such as phosphor bronze and beryllium steel, and has inferior conductivity compared to conventional brushes made of noble metals and noble metal alloys. Highly conductive metals such as silver (Ag) and steel (Cu)
It must be composed of Further, the carbon contained in the commutator acts as a solid lubricant and has the effect of smoothing sliding contact between the brush and the metal of the commutator, which have a high coefficient of friction. It also has the effect of reducing arcs that occur when switching the current supplied to the rotor windings.

Next, the effects of the rectifying device of the present invention in terms of production will be explained below.

Methods for holding the non-sliding end of the brush with the fiber bundle 8 include heat-pressing, caulking, adhesive fixation, etc. In the brush device of the present invention, the fiber bundle 8 of metal wire with a diameter of 100 to 200 μ is coiled. The product is manufactured using a simple method with a small number of steps, such as directly loading the product, cutting it to a predetermined size using a laser, and welding it to the terminal plate, resulting in high productivity.

As described in detail of the invention, with comb-shaped holding structure, diameter 100-200
The rectifying device of the present invention made of metal fibers having an elasticity of μ has a vibration damping function with a multi-contact slider, so the rectifying waveform is good and mechanical and electrical noise is small. Furthermore, the commutator segments are made of a sintered alloy containing 10 to 20% carbon in a highly conductive metal, so they slide smoothly. The elasticity of the brush can be selected from a wide range of combinations of wire diameter and length, and the force changes little in response to minute displacements of the brush.It follows commutator rotation well and suppresses the amount of arcing that occurs when switching current. It will be done. In addition, multiple contacts, smooth sliding, and reduced arc generation lead to longer brush life and lower noise. In addition, the number of man-hours required to manufacture the brush device from the fiber material is small (there is no manual work such as pasting vibration-proofing material to the conventional leaf spring, so automation is easy and productivity is improved). In addition, the fiber brush is welded to the brush plate and does not use adhesive, so there is no influence of temperature and humidity on contact stability and anti-photography effect.
Become.

[Brief explanation of the drawing]

FIG. 1 shows a brush according to an embodiment of the present invention, (A) is a front view, (
B) is a side view, FIG. 2 is a perspective view of the main parts of a rectifier for a small DC motor according to an embodiment of the present invention, FIG. 3 (A> is a rectification waveform diagram, and (B) is a diagram showing mechanical noise. (C) is a graph comparing the mechanical noise between the conventional model and the inventive model.
The figure is a longitudinal sectional view of a conventional brush structure, and FIG. 5 is a perspective view of another conventional fiber brush. 7... Comb-shaped holding plate, 8... Fiber bundle, 9
・・・・・・Commutator. Name of agent: Patent attorney Toshio Nakao and 1 other figure 3 (A) (B) (C)

Claims (2)

[Claims] (1) A brush with a sliding part made of a bundle of metal wires aligned in one direction, and a commutator with a sliding surface in contact with the sliding part made of a sintered body of metal containing carbon. A rectifier for small motors. (2) The rectifying device for a small motor according to claim 1, wherein the free end of the metal wire is supported by a comb-shaped holding plate having a plurality of slits.