WO1997031420A1

WO1997031420A1 - Spark-free commutator

Info

Publication number: WO1997031420A1
Application number: PCT/JP1996/001998
Authority: WO
Inventors: Osami Matsumoto
Original assignee: Osami Matsumoto
Priority date: 1996-02-26
Filing date: 1996-07-18
Publication date: 1997-08-28

Abstract

A commutator for a D.C. generator and a D.C. motor equiped with a commutator type armature, comprising metal commutator segments (1), sliding electrodes (2) of metal in the same number as that of the commutator segments, three or four diodes (3), and copper wires (4) for connecting the sliding electrodes. Therefore, a short-circuit current generated by an armature reaction between the commutator segment and the armature coil short-circuited by a brush is bypassed to avoid the interruption of short-circuit current and thus no spark is generated between the commutator and the brush. When the commutator of the invention is used, the commutator and the brush are protected from burnout due to the occurence of the spark, so that their service life can be prolonged, and maintenance-free devices can be accomplished depending on applications. Moreover, the commutator can be produced at a low cost, and can be applied not only to small D.C. motors using a permanent magnet for a stator but also to large D.C. generators and D.C. motors in which compensating windings and auxiliary poles cannot be disposed because the structure is complicated and expensive.

Description

Commutator that does not emit sparks

The present invention relates to a DC motor having a commutator-type armature and a commutator that does not generate a spark and is used for a DC generator. Background art

Conventionally, DC motors and DC generators equipped with commutator-type armatures rotate while the commutator is in sliding contact with the brush, so a spark is generated in the gap between the commutator piece and the brush when the electrical path breaks. Was to do. For this reason, the commutator and the brush suffered burnout wear due to sparks in addition to wear due to sliding contact, and maintenance such as replacing the brush at regular intervals and smoothing the commutator surface was required.

Spark generation in the gap between the commutator strip and the brush is caused by the well-known armature reaction described below. Due to this armature reaction, the geometric neutral axis, which is the midpoint between the stator NS poles, is shifted in the rotating direction of the armature in the generator and in the opposite direction in the motor. This is called an electrical neutral axis, and the deviation angle between the two varies depending on the magnitude of the armature current.

Therefore, the geometric neutral axis is no longer the midpoint between the NS poles where the magnetic flux density is zero, and if a brush is located at this position, the induced electromotive force is applied to the armature coil shorted by the brush. Occurs and short-circuit current flows. The short-circuit current due to the induced electromotive force is proportional to the magnitude of the armature current, and is proportional to the deviation angle between the geometric neutral axis and the electrical neutral axis. Therefore, when a load is applied, the armature current naturally increases, and the short-circuit current also increases. This short-circuit current breaks the electrical path when one of the commutator strips separates from the brush as the commutator rotates, causing a spark in the gap between the two.

Large DC motors and DC generators are provided with compensation windings and auxiliary poles on the stator side as countermeasures to reduce the occurrence of sparks, but permanent magnets are often used for the stator. Due to the structural and size restrictions of small DC motors, and even those that do not use permanent magnets for the stator, expensive DC windings and auxiliary poles with complicated structures are required. Not used for these.

Other measures to reduce the generation of sparks include the use of a brush made of a material with a large contact resistance to reduce the short-circuit current by moving the brush to the position of the electric neutral axis, adjusting the brush brushing accuracy, adjusting the brush pressure, and Some measures have been taken, such as the use of commutators that use materials that reduce spark generation.

Further, various inventions for suppressing the above-mentioned generation of sparks have also been filed. For example, a conductive sheet (Tay 1 or US Pat. No. 3,409,788) which generates an eddy current which is arranged in a magnetic flux region and suppresses a change in magnetic flux, a resistor connected in series to a brush element ( Uemu ra et al., U.S. Pat. No. 3,456,143), resistive paths (Kaneko et al., U.S. Pat. No. 3,487,248), quenching capacitors provided between rectifier sites (U.S. Pat. No. 3,594,598 to Schaub), Low voltage surge protector (Jonassen, U.S. Pat. No. 3,890,543); conductive grease for spark quenching to cover and fill between rectifier sections (Mupchi, U.S. Pat. No. 4,391,153). Gazette), a molded underwater motor equipped with a surge absorbing unit (US Pat. No. 4,443,027, Yamamoto et al.), A combination of an insulating washer and a conductive ring disposed near a rectifier (US Pat. No. 4,734,607 to Ikawa et al.) ) And rectifier type electrical equipment That the method and apparatus for a spark suppression (Ma rtin R. Mc LE ND〇N Japanese Unexamined Patent Publication No. 6-54449-9).

Of these, Yamamoto et al., U.S. Pat. No. 4,473,027 and U.S. Pat. No. 3,890,543 of J0nassen both disclose limitations on the surge voltage applied to the rotor. This is a limitation of the surge voltage on the stator side, and its effect does not extend to prevention of sparks on the rotor side.

M artin R. M c LEND〇 N Japanese Patent Application Laid-Open No. 6-54449 / 1999 discloses that the surge voltage is cut using the characteristics of a zena diode to keep the current flowing through the armature coil constant. This does not eliminate the flashover between the commutators and the spark generated by the induced electromotive force in the short circuit of the coil formed by short-circuiting with the brush. In addition, since the present invention uses twice as many Zener diodes as the number of commutator pieces, mounting it on an armature having a large number of commutator pieces requires a considerable storage space.

Due to the various technical, structural, and economic constraints mentioned above, DC generators and commutator DC motors are However, there is still a problem of spark generation and it has not been completely solved. Therefore, a method for eliminating the generation of sparks is still desired today, and the commutator of the present invention is intended to meet the demand. Disclosure of the invention

The current has a property of continuing to flow when it starts to flow, and when the electric circuit is cut, the electric current flows in the air between the conductor ends of the separated electric circuit in an attempt to flow, and a spark is generated.

In DC motors and DC generators equipped with commutator-type armatures, a short-circuit current due to induced electromotive force occurs in the armature coil shorted with a brush during commutation. However, this short-circuit current generates a spark in the gap when one of the two commutator pieces that are in sliding contact with the brush is separated from the brush.

As a countermeasure to eliminate this spark, one of them is to provide a compensation winding and an auxiliary pole to return the electrical neutral axis due to the armature reaction to the geometric neutral axis, and to reduce the short-circuit current due to the induced electromotive force. To reduce the short-circuit current due to the induced electromotive force by generating a current opposite to this short-circuit current at the auxiliary pole, the second is to use a brush with a material with a large contact resistance to short-circuit the short-circuit current There is a method to reduce the number.

The commutator of the present invention is provided with a bypass circuit using a “diode and a sliding electrode and a bridging wire” in the above circuit, shunts a short-circuit current, eliminates the circuit, and circulates a current in the bypass circuit. At the same time as supplying a "negative current from the power supply", also known as flyback (Flyback), to eliminate sparks.

The details of the configuration and operation of the commutator of the present invention will be described with reference to FIGS. 4 to 7. FIG. 4 shows a state where commutation has started, and a positive electrode is provided at the center of the commutator piece (111). The brush (8) is in contact and a positive current (11) is flowing from the power supply (10). The diode (3-1) has its anode side connected to the commutator strip (1-1) and its power source side connected to the sliding electrode (2-1). Each of the crossover wires (4) connects the crossover sliding electrodes (2-1) and (2-2), and (2-2) and (2-3). Each coil (5) connects between the commutator pieces, but does not directly connect to the cross slide electrodes.

The commutator rotates and the state shown in Fig. 5 is reached, and the positive brush (8) comes into contact with the commutator piece (1-1-1), the passing sliding electrode (2-1) and the commutator piece (1-1-2). Then, a short circuit (1 2) is formed between the coil (5) and the short circuit, which conducts the current in the opposite direction to the forward positive current (1 1) from the power supply (10). A short-circuit current flows due to the electromotive force. When the commutator further rotates and reaches the state shown in Fig. 6, when the commutator piece (11-1) moves and moves away from the positive brush (8), the supplied positive current becomes diode (3-1). ), Passing through the passing sliding electrode (2_1), the positive brush (8) commutator strip (1-1-2) → coil (5)-diode (3-1) and circulating current (13), and at the same time, The short circuit disappears.

This circulating current has a very short duration and disappears instantaneously, but cancels the short-circuit current. The bypass circuit, which connects the diode (3-1) and the sliding electrode (2-1), shunts the current flowing through the commutator strip (1-1) and the positive brush (8). Does not generate sparks. In addition, the circulating circuit acts to supply “negative current (14)” from the power source, also called flyback (flyback), so that the sliding electrode (2-1) passes from the positive brush (8) to the positive electrode brush (8). Even if it separates, it does not generate a spark in the gap, it becomes the state shown in the figure, and the commutator piece (1-2) replaces the commutator piece (1-1-1) at the start of commutation. End the commutation.

Diodes may be connected to all the commutator pieces and the sliding electrodes, but connecting an equal number of diodes to the armature with a large number of commutator pieces will result in rectification with insufficient storage space. Considering the surroundings of the wires, it is not preferable in terms of structure, and the manufacturing cost increases. Therefore, a crossover wire (4) should be provided instead of the diode.

Although the crossover wire (4) is a short copper wire, it works in place of the diode (3) by short-circuiting between the crossover slide electrodes (2). The number and usage of the crossover wire (4), crossover slide electrode (2) and diode (3) will be described with reference to FIGS. 3, 8, and 9.

The diode (3) that connects the commutator piece (1) and the sliding element ¾H (2) connects the cathode side to the commutator element (1) and the power source side to the sliding electrode (2). The diode (3) consists of three, five, six commutator segments (1), For commutators with 7, 9, 10, 11, 12, 12, 13, 14 or 15 etc., use 3 commutators and 8 commutator pieces (1) Alternatively, use a minimum of three, and at most four, equally divided, using four commutators with sixteen commutators.

The crossover wire (4) connects between the other crossover sliding electrodes (2) without the diode (3) connected, only one of which is connected to the force side of the diode (3). Connect to the passing slide electrode (2). In other words, the crossover line (4) does not allow the connection between the commutator strip (1) connecting the crossover slide electrode (2) and the crossover slide electrode (2).

Since the bridging slide electrode (2) is short-circuited across the stepping stone with the bridging wire (4), if less than three diodes (3) are used, the distance between the pair of positive and negative bipolar brushes It is necessary to use a minimum of three diodes as approaching distances can cause the bipolar brushes to short out.

In addition, the cross slide electrode (2) will hinder operation unless the circumferential width thereof is smaller than that of the commutator piece (1). Therefore, the following description will be made in the “Best mode for carrying out the invention” described later. It is necessary to have the shape described in FIG. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing the entirety of a DC motor equipped with the commutator of the present invention, and FIG. 2 is a diagram showing details of the commutator. FIG. 3 is a connection diagram of a brush and an armature coil and a commutator having nine commutator pieces of the present invention, and FIGS. 4 to 7 are diagrams showing a transition of a rectifying action between the brush and the commutator. FIG. FIG. 8 and FIG. 9 are electric circuit diagrams of a commutator having 15 or more commutator pieces. BEST MODE FOR CARRYING OUT THE INVENTION In order to illustrate the present invention in more detail, it will be described in turn with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a state in which a commutator of the present invention is mounted on a model small-sized DC motor using permanent magnets for a stator and three armature coils. Since a practical small DC motor is covered with a soft iron cylindrical cover and the form of the brushless commutator is not visible, the illustration of the present invention is based on the model manufactured for the experiment. It was made with some modifications to the drawing. The commutator is exaggerated to be larger than the whole motor, so that the configuration of the commutator pieces, the sliding electrodes and the diodes can be easily understood.

FIG. 2 shows details of a commutator piece (1), a cross slide electrode (2), and an insulator (7) for fixing both, which constitute the commutator of the present invention. As is evident from the figure, the width of the cross slide electrode (2) on the circumference is narrower than that of the commutator strip (1), and the length in the XI-X biaxial direction is rectified. It is about half of the child piece (1).

When the passing sliding electrode (2) having the same width as that of the commutator piece (1) is inserted between the commutator pieces (1) over the entire length, the passing sliding electrode (2) comes into contact with the brush. During this period, the current from the power supply does not flow, so the armature is not excited, and an unexpected pulse width control effect is generated, and the rotation speed is reduced. This phenomenon becomes more remarkable as the width of the sliding electrode (2) becomes wider. Therefore, change the viewpoint, change the shape of the sliding electrode (2) into a longitudinal wedge shape, and reciprocate the brush in the longitudinal direction. If the off-time of the supply current can be changed, the rotation speed can be variably controlled. However, this kind of control method by lateral movement of the brush applying this derivative phenomenon is theoretically aside, not practical, but rather a drawback that does not fit the purpose of use of the present invention.

In order to eliminate this drawback, the force that requires the width of the cross-sliding electrode (2) to be as small as possible is limited. About the width of the commutator piece. In the present invention, the following method is adopted. The arc width W and the clearance C on the XI side of the commutator segment (1) are the same as those of the conventional commutator segment. The arc width T on the X2 side is made smaller than W, and S × W—C—T and , W〉 T〉 4C. In addition, the width of the rotor piece (1) is reduced from a position near half the length X of the effective sliding portion in the direction of the XI-X2 axis, and the commutator piece (1) is placed between the two pieces. , The width is S, and the length Z is Z> X ÷ 2 + R. As a layout with interleaved sliding electrodes (2), these are used as commutators fixed with insulators (7). A positive brush (8) and a negative brush (9) are installed near one-half the length X of the effective sliding part.

By using the commutator and the brush configured as described above, the brush is in sliding contact with the front commutator piece (1) and also in sliding contact with the transfer sliding electrode (2). Since the current passes through the rear commutator piece (1), the time during which no current is supplied is negligibly small, and the rotation speed does not decrease. The above clearance C is preferably in the range of 0.3 to 0.5.

FIG. 3 is a connection diagram of a brush, a coil of an armature, and a commutator having nine commutator pieces of the present invention. In the perspective view as shown in FIG. 1, nine commutators are shown. Since it is difficult to illustrate the layout of the pieces, the crossover sliding electrodes, the diodes, the crossovers, etc., and the details of the wiring, they are represented as shown in this figure.

Fig. 4 to Fig. 7 illustrate the process in which the rectifying action of the brush and the commutator 行わ is performed in the order of the processes. The features of the present invention are that, unlike a conventional commutator composed of only a commutator piece, a “sliding sliding electrode” is provided, and a “diode on the armature side that rotates at high speed” is provided. Yes, in order to briefly explain its features, the illustration method used here does not dare to mention the role of the crossover.

Figures 8 and 9 show the “crossover” to save on the diodes used. It is a figure which put emphasis on the illustration of the usage of. Although it is theoretically possible, it is practically impossible to provide the same number of diodes on the “armature side” as the number of commutator pieces increases. In such cases, use short copper wires "four wires (4)" which will replace the diode (3). No matter how many commutator pieces (1) are used, only three or four diodes and some copper wires cut short for the crossover (4) can be used.

FIG. 8 shows a commutator having 15 commutator pieces, using three diodes (3) and twelve crossover wires (4). FIG. 9 shows a commutator having 16 commutator pieces, in which four diodes (3) and twelve crossover wires (4) are used. In each of the above two examples, the diodes (3) are arranged evenly around the circumference so that rotation irregularities do not occur even when the armature rotates at high speed. The diode must be firmly fixed to the armature so that it will not be scattered by the centrifugal force of the high-speed rotation of the armature. Industrial applicability

As described above, the non-sparking commutator of the present invention can be manufactured easily and at low cost, so that the structure is complicated and expensive, as well as a small DC motor using a permanent magnet for the stator. For this reason, it can be used for all large DC generators and DC motors that cannot be provided with a compensation winding and a supplementary pole. An example of a specific effect when the commutator of the present invention is adopted will be described below.

Even in the case of a large motor with a compensating winding and an auxiliary pole, if the gap between the auxiliary pole and the armature is widened, the magnetic flux of the auxiliary pole will weaken, causing insufficient commutation and sparking from the rear end of the brush. Conversely, if the gap between the auxiliary pole and the armature is reduced, over commutation will occur and sparks will be generated from the front end of the brush, so the gap between the auxiliary pole and the armature must be adjusted. However, even in this case, if the commutator of the present invention is used, it is possible to eliminate the generation of sparks even if the adjustment is rough. Can be.

If the commutator of the present invention is mounted, in a small DC motor, the brush is installed not on the electric neutral axis but on the geometric neutral axis, and even when the brush is rotated forward or backward, the spark is generated. No spark is generated even when a large load is applied to the rotating armature shaft as long as the motor is used at the rated current.

For large DC generators and DC motors, even if the brush is installed at the position of the electric neutral axis in accordance with the forward or reverse rotation direction, the brush will not change according to the load fluctuation. Position adjustment is required, but the use of the commutator of the present invention eliminates that need.

As described above, by employing the commutator of the present invention, all DC generators and DC motors using brushes can eliminate the burning and abrasion of the commutator and brushes due to spark generation, prolong the life of the brush, and increase the product life. In some applications, maintenance-free operation is possible.

Moreover, the commutator of the present invention continues and develops a compact structure utilizing the characteristics of a simple mechanism that combines a conventional commutator and a brush. There are three kinds of sliding electrodes, three or four diodes and three kinds of copper wires used for crossovers. Therefore, as a matter of course, the increase in the manufacturing cost is insignificant.

Claims

The scope of the claims

1. The commutator of the present invention is composed of a plurality of metal commutator pieces (1) for connecting the wire ends of the armature coils, and has a completely different feature, namely, the current flowing through the commutator pieces (1). Of these, the same number of commutator strips that perform the function of passing only negative current and the same number of metal sliding electrodes (2), three or four diodes (3), and the passing sliding electrodes (2) and the passing sliding electrodes It has a copper bridge (4) for connecting (2). The cross slide electrode (2) is inserted between a plurality of commutator strips (1), both of which are arranged alternately. The three or four diodes (3) are composed of three or four commutator segments (1) that are equally or approximately equally arranged among the arranged commutator segments (1). The anode of the commutator is connected to one of the sliding electrodes (2) on both sides of the commutator piece (1) to which the anode is connected. At this time, when the commutator is viewed from the axial direction of the armature shaft (6), when the force side of the diode (3) is connected to the sliding electrode (2) in a clockwise direction, the passing sliding electrode ( From 2), in the same clockwise direction, connect the crossover wire (4) to the next crossover slide electrode (2). Repeat the connection of the next crossover wire (4) to the next next crossover slide electrode (2), and the crossover slide electrode immediately before the commutator piece (1) to which the second diode (3) is connected. (2) Stop at the connection up to. The same applies to the remaining second, third and fourth diodes (3). If it is counterclockwise, turn it counterclockwise in the same order as above. All of the commutator pieces (1) and the sliding electrodes (2) are fixed with insulators (7). Claims are directed to a commutator having a structure configured as described above.

2. The number of bridge sliding electrodes (2) used is the same as the number of commutator strips (1), and the number of diodes (3) used is three or four. Claims that include the same number as the sprue pieces (1), and the crossover wire (4) to be the quantity obtained by subtracting the used quantity of the diode (3) used from the used quantity of the commutator pieces (1) The commutator according to item 1.

3. The commutator piece (1) has a diameter D centered on a line segment X1-X2 connecting the point X1 and the point X2, and its outer peripheral length is L = n (W + C). Here, n is the number of commutator pieces. Also, the arc width on the X1 side of the commutator segment (1) is W, the arc width on the X2 side is T smaller than W, and the clearance between two adjacent commutator segments (1) is C, However, C is about 0.3 to 0.5 mm. On the other hand, the length of the effective sliding part of the commutator piece (1) in the axis X1—X2 direction is X, the length of its riser is R, and the clearance (G) on the X2 side is effective. From the half of the length X of the sliding part to the direction of the point X2, the width is reduced to G = 2 x C + S. The cross slide electrode (2) has the length Z of the sliding portion as Z> X ÷ 2 + R, and the arc width S as S <W—T—C and W> T> 4C. I do. 2. The commutator according to claim 1, wherein the shape of both the commutator piece (1) and the cross slide electrode (2) is in the above-mentioned dimensional relationship.

Corrected paper (Fiber iJ91)