JP3360092B2 - Carbon commutator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutator useful for a motor used in a fuel supply pump for supplying a liquid fuel to an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art In an internal combustion engine such as an automobile, a motor for a fuel supply pump is used to supply fuel.
Gasoline used as a fuel includes gasoline containing alcohol called gasohol and bad gasoline mixed with alcohol or the like unduly. When such poor gasoline is used, the commutator made of copper used for the motor for driving the fuel supply pump reacts with the alcohol in the gasoline to reform the fuel itself, or the copper erodes and rectifies the fuel. There is a problem of deteriorating the child function.

[0003] In view of the above problems, several types of carbon commutators using carbon as commutator pieces have been proposed as commutators for gasoline countermeasures. As a first proposal, the carbon commutator shown in US Pat. No. 5,175,463,
The flat part of the sintered carbon is nickel-plated, and the nickel-plated plane is soldered or joined using a conductive adhesive to the flat part of the metal fitting made of copper with the terminals protruding outward. Configuration.

[0004] As a second proposal, a carbon commutator proposed by the applicant in Japanese Patent Application No. Hei 6-284240 is, for example, a method in which metal powder is applied to the outer periphery of a carbon sintered body formed in a disk shape. A terminal is formed integrally with the conductive metal sintered body, and an armature coil is connected to the terminal. Further, as a third proposal, a carbon commutator previously proposed by the applicant in Japanese Patent Application No. Hei 6-178503 is
The material for forming the carbon layer is such that a mixture of carbon powder and a carrier made of, for example, phenol resin is injected into a resin holder.

However, in the carbon commutator of the first proposal, since the flat portion of the sintered carbon is nickel-plated, the plating solution penetrates into the sintered carbon during plating. However, there is a problem in that the plating solution remains for a long period of time and the carbon commutator pieces themselves are modified. Furthermore, since the metal fitting and the sintered carbon body are joined by solder or a conductive adhesive, there is a problem that the reliability is lowered due to a variation in the joining strength and the cost is increased.

Further, the carbon commutator of the second proposal has a drawback that the terminal is hardly extensible because the terminal is a sintered body, and a so-called fusing method in which a coil element wire is sandwiched and pressed and heated for connection cannot be used. I have. Furthermore, the carbon commutator of the second proposal also has a problem that when the ratio of carbon powder in the mixture is increased in order to increase the conductivity of the commutator pieces, the mechanical strength is reduced.

[0007]

In view of the above problems, the present invention has no influence on alcohol in gasoline, can be manufactured at low cost, and has a low mechanical strength.
The aim is to provide a carbon commutator that can be enhanced .

[0008]

DISCLOSURE OF THE INVENTION In view of the above problems, a plurality of commutator pieces arranged flat through slits and a riser which is joined to the commutator pieces and extends radially. A commutator comprising: a plurality of conductive metal plates formed by projecting pieces; and a boss portion made of an electrically insulating synthetic resin having a shaft hole formed at the center while supporting at least the metal plate. The plurality of commutator pieces are made of carbon powder, and the carbon powder is formed into a single body by compacting and sintering the metal plate. Form a jetty
Each commutator in the recess surrounded by this jetty
The gist is to accommodate the piece and each conductive metal plate .

[0009]

According to the carbon commutator of the present invention, a plurality of commutator pieces are made of carbon powder, and the carbon powder is formed into a single body by sintering and compacting the metal plate. Since a powder metallurgy method, for which a mass production technique has already been established, can be employed in the manufacturing process, a commutator having low cost, high reliability, and stable quality can be formed. Further, when the commutator piece is formed of carbon, chemical resistance is improved and chemical stability is excellent, so that the gasoline itself is prevented from being reformed without being affected by alcohol or the like in gasoline. Further, when the sliding layer of the commutator piece made of carbon is combined with a carbon brush, the wear resistance is improved because of the same material. Also, the outer periphery of the commutator piece
If the inner periphery is surrounded by the resin of the boss, the commutator piece will be damaged.
Accidents such as damage can be prevented. Furthermore,
The linear expansion coefficient of the conductive metal plate and the conductive layer bonded to it
Approximate or equal, it is produced by shrinkage during firing, etc.
The problem of easily peeling or cracking can be prevented.
Wear.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a carbon commutator according to the invention.
FIG. 1 is a sectional view of a carbon commutator, and FIG.
FIG. 3 is a plan view, FIGS. 3 to 5 are explanatory views showing intermediate steps of the carbon commutator, and FIGS. 6 to 8 show another embodiment of the present invention.

In FIG. 1 and FIG. 2, a flat carbon commutator 1 has a plurality of conductive metal plates 3 and a plurality of conductive metal plates 3 which are arranged at equal intervals in the circumferential direction so as to be joined to the conductive metal plates 3. It is composed of a commutator piece 5 and a boss 2 connecting the plurality of commutator pieces 5 and the conductive metal plate 3 separated from each other. The plurality of conductive metal plates 3 are arranged flat at equal intervals in the circumferential direction as a whole. This conductive metal plate 3 is selected from copper as a metal having good spreadability,
A riser piece 3a protrudes from the outer peripheral end of each metal plate 3, and a plurality of claws 3b that integrally engage with the boss 2 during insert molding are formed protruding from the inner peripheral end of the center hole. . The riser piece 3a is bent along the peripheral surface of the boss portion 2 and has a distal end portion bent in a U-shape, so that a coil end of an armature coil described later can be connected by crimping.

Furthermore, a plurality of commutator pieces 5 are integrally arranged on the plurality of conductive metal plates 3 in a circumferential direction at positions corresponding to the individually separated metal plates 3. The commutator piece 5 is formed by compacting the carbon powder with the metal plate 3 and then firing. At this time, the commutator piece 5 is not detached from the metal plate 3 so that
A substantially triangular through-hole 3c is punched out of the metal plate 3, and each commutator piece 5 is engaged.
That is, the commutator piece 5 is communicated with the front and back surfaces through the through holes 3c of the metal plate 3 at the time of compacting, and the other surface of the thick sliding portion 5a formed on one side surface of the metal plate 3 has a flange portion. 5b is formed and engaged. Further, a coupling projection 5c for coupling to the boss 2 is integrally formed on the commutator piece 5 exposed on the other surface side of the metal plate 3 at the time of compacting. Since the commutator pieces 5 are bonded to the front and back surfaces of the metal plate 3 in this manner, the contact resistance between the two is reduced, and the variation in the resistance value between the riser piece 3a and the sliding surface on the front surface between the commutator pieces 5 is reduced. There is the advantage of reducing.

A slit 4 for electrically insulating each commutator piece 5 and the conductive metal plate 3 is provided between adjacent ones. The plurality of commutator pieces 5 and the conductive metal plate 3 are separated from each other by the slits 4, but are connected to each other by the boss 2.
The boss portion 2 is made of a synthetic resin having electrical insulation properties, and the commutator piece 5 is housed in a recess surrounded by annular ridges 2a and 2b formed on the outer periphery and the inner periphery of the upper surface.

An axial hole 2c is formed in the center of the boss portion 2 in the axial direction, and is fitted and fixed to a rotating shaft of a fuel supply pump motor (not shown), for example. Further, the coil end of the armature coil of each phase of the motor is inserted into the U-shaped riser piece 3a formed on each metal plate 3, and then connected by a so-called fusing method in which the armature coil is sandwiched and pressed and heated. ing. Further, a pair of brushes made of, for example, carbon (not shown) provided in the motor is slidably contacted with the surface of the plurality of commutator pieces 5 formed by the carbon powder, and the brush is energized by energizing the brushes. The motor rotates.

The commutator piece 5 is desirably made of carbon powder having the same properties as the carbon brush. The carbon powder itself has good slidability, and the wear resistance between the carbon powder and the carbon brush is remarkably improved, so that the durability of the motor is improved. In addition, since carbon is used as the sliding surface, it has excellent chemical resistance and chemical stability, and when used for a fuel supply pump motor, there is no problem with startability even after a long non-operation period There are advantages. On the other hand, in order to ensure electrical connection between the conductive metal plate 3 and the commutator piece 5, a metal conductive layer formed by compacting only a conductive metal powder and firing is provided around the metal plate 3. Form and on it
A sliding layer made of the carbon powder may be formed. As described above, when the metal conductive layer is formed, the linear expansion coefficient of the metal plate 3 is close to that of the metal plate 3, so that there is an advantage that the problem of peeling or cracking, which is likely to occur due to shrinkage during firing, can be prevented.

In order to more effectively solve such a problem, a metal-carbon mixed powder having a large mixing ratio of metal powder is used around the metal plate 3 so that the ratio of carbon powder is increased toward the sliding layer. May be formed in a plurality of layers in which a mixed conductive layer having a large number is formed. As a method of forming the commutator pieces 5 having a plurality of layers, first, the metal plate 3 is placed in a mold (not shown), and an appropriate amount of the metal-carbon mixed powder is added to the metal plate 3 in descending order of the mixing ratio of the metal powder. , And finally, after the carbon powder is charged, insert compaction is performed and firing is performed together with the metal plate 3. Although copper powder is selected as the conductive metal powder, nickel powder may be applied to the surface of the copper powder.

At this time, if the metal conductive layer is made as thin as possible so that it can be joined to the conductive metal plate 3, it is advantageous in terms of cost. Further, in addition to the above-described method of simultaneously molding the sliding layer 52 and the metal conductive layer, a metal conductive layer is formed in advance by powder compaction, and then the metal conductive layer is placed in a mold, and a predetermined amount of the metal conductive layer is formed. Carbon powder may be charged and both may be insert-compressed by powder metallurgy (sintering). Conversely, the metal conductive layer may be formed by insert compression after forming the sliding layer.

Next, an example of a method for manufacturing the carbon commutator 1 will be described with reference to FIGS. As shown in FIG. 3, the conductive metal plate 3 is formed by pressing a copper plate having an appropriate thickness by pressing to form a plurality of riser pieces 3 a and a plurality of claws 3 b, and a flat annular portion. The through holes 3c are punched and formed so as to correspond to the respective commutator pieces 5. The exposed portion of the conductive metal plate 3, particularly the exposed portion such as the riser piece 3 a, is plated with tin or the like, and a protective film is formed to prevent copper as a base material from being eroded by alcohol or a crude component in gasoline. May be.

The conductive metal plate 3 is then placed in a molding die (not shown), a predetermined amount of carbon powder is put into the die, and a compact is formed by an appropriate press or the like as shown in FIG. As a result, the original shape of the commutator piece 5 is formed. In this compact formation, two coupling projections 5c are integrally formed on the lower surface of the commutator piece 5, respectively. Then, the commutator pieces 5 are put together with the metal plate 3 in a firing furnace or the like, and the carbon powder formed into the powder is fired. As described above, the metal powder or the mixed powder of the metal and the carbon may be formed sequentially from the periphery of the metal plate 3 in order of increasing the mixing ratio of the metal powder in the order of increasing the mixing ratio.

In the next step, a riser piece 3a projecting from the outer periphery of the metal plate 3 and a plurality of claws 3b projecting from the inner periphery are bent to predetermined dimensions. Thereafter, such an intermediate product was placed in a molding die (not shown), and as shown by the two-dot chain line in FIG. 5, the plurality of riser pieces 3a and one end face were exposed, and the powder was formed. The boss portion 2 is insert-molded with a synthetic resin having electrical insulation so as to surround the outer peripheral portion and the inner peripheral portion of the commutator piece 5. As a result, the commutator piece 5 is formed in a state of being housed in a recess surrounded by the annular ridges 2a and 2b formed in the boss portion 2. Further, at the center of the boss portion 2 at the time of the insert molding, a shaft hole 2a for fitting and fixing to a rotating shaft of a fuel supply pump motor (not shown) is formed in the axial direction.

At this time, the claws 3b protruding from the metal plate 3 and the coupling projections 5c formed on the lower surface of the commutator piece 5 are buried in the boss portion 2 and engaged with the resin, so that the commutator is engaged. The connection between the piece 5 and the boss 2 is made strong.
In particular, the commutator piece 5 is prevented from detaching from the resin of the boss portion 2 with respect to the stress applied in the centrifugal force direction. Further, if the outer peripheral portion and the inner peripheral portion of the commutator piece 5 are surrounded by the resin of the boss portion 2, an accident such as damage to the commutator piece 5 during a subsequent manufacturing process or a process of assembling to the motor may occur. There is an advantage that can be prevented.

Thereafter, as shown by the solid line in FIG. 5, the distal ends of the plurality of riser pieces 3a are bent in a U-shape. Further, slits 4 are formed at equal intervals in the circumferential direction of the commutator pieces 5 and the conductive metal plate 3 using a slicer such as a cutting grindstone. As a result, the commutator pieces 5 and the conductive metal plate 3 are made independent while being electrically insulated through the slits 4, but are connected to each other by the boss 2. On the other hand, a coil wire is connected to the plurality of riser pieces 3a having the distal ends bent in a U-shape after being assembled into a motor. However, since a metal having high extensibility is used, the fusing method is used. There is an advantage that a general-purpose inexpensive and reliable connection method can be adopted.

6 and 8 show a second embodiment of the present invention. FIG. 6 is a sectional view of a carbon commutator, FIG. 7 is a plan view thereof, and FIG. 8 is a plan view of a conductive metal plate. is there.

5 to 8, the difference from the above-described embodiment is that the conductive metal plate is formed in a rectangular band shape, and each commutator piece surrounds each conductive metal plate. It is. That is, in the conductive metal plate 31, the strips 31c are arranged in a flat radial shape at equal angular intervals in the circumferential direction.
The conductive metal plate 31 is made of copper. Each strip 31c has a riser piece 31a formed at an outer end thereof, and a plurality of engagement pieces formed at the inner end of the center hole into the boss portion 2 during insert molding. Are formed integrally with each other. The riser piece 31a is formed to be bent along the peripheral surface of the boss portion 2 as in the above-described embodiment, and the tip portion is formed to be bent in a U-shape. The coil ends of the armature coils constituting the motor are crimp-connected to the riser pieces 31a, respectively.

Furthermore, commutator pieces 51 are arranged at equal intervals in the circumferential direction on each strip 31c of the conductive metal plate 31 having the above-described configuration. The commutator piece 51 is formed by integrally compacting carbon powder so as to surround the strip 31c, and then firing. As described above, the commutator pieces 5 surround the band-shaped piece 31c, so that the individual commutator pieces 5 are engaged with each other to prevent the two pieces from separating from each other, and the commutator piece 51 and the conductive metal plate 31 are electrically connected. Are connected so as to conduct. Further, the commutator piece 51 has a coupling projection 51c for coupling to the boss portion 2.
Are formed integrally during compacting.

Each commutator piece 51 and the conductive metal plate 31
A slit 41 for electrically insulating each of them is provided between adjacent ones. The plurality of commutator pieces 51 and the conductive metal plate 31 are separated from each other by the slits 41, but they are connected to each other by the boss 2.

An axial hole 2c is formed in the center of the boss portion 2 in the axial direction, and is fitted and fixed to, for example, a rotating shaft of a fuel supply pump motor (not shown). Further, the coil ends of the armature coils of the respective phases of the motor are inserted into the U-shaped riser pieces 31a formed on the respective metal plates 31, and then connected by a so-called fusing method in which the armature coils are sandwiched and pressed and heated. ing. In addition, a pair of brushes made of, for example, carbon (not shown) provided in the motor is slidably in contact with the surface formed by the carbon powder of the plurality of commutator pieces 51, and the brush is energized by energizing the brushes. The motor rotates.

The commutator piece 51 described above may be entirely formed of carbon powder having the same properties as the carbon brush. However, the electrical connection between the conductive metal plate 31 and the commutator piece 51 is ensured. At the same time, in order to prevent the problem of peeling or cracking that is likely to occur due to shrinkage or the like during firing, for example, the metal powder 3 has a large mixing ratio of the metal powder alone or the metal powder on the lower surface from the strip 31c of the metal plate 3. The metal conductive layer 51a may be formed of a metal-carbon mixed powder, and the sliding layer 51b may be formed of a carbon layer having the same properties as the carbon brush on the upper surface from the strip 31c. Alternatively, a thin metal conductive layer 51a may be formed around the upper and lower surfaces of the strip 31c of the metal plate 3, and a sliding layer 51b on which the carbon brush slides may be integrally formed on the upper surface side.

Next, the manufacturing method of the above-described second embodiment will be described. First, as shown in FIG. 8, a conductive metal plate 31 is formed by pressing a copper plate having an appropriate thickness, as shown in FIG.
The strips 31c are radially arrayed at equal angular intervals in the circumferential direction, and a connecting portion 3 is provided at an outer end and a center end of each strip 31c.
They are connected to each other by 2,33. A riser piece 31a is formed in the vicinity of the connecting portion 32 on the outer end side, and a plurality of claws 31b are formed in the boss portion 2 in the vicinity of the center end so as to engage during insert molding.

The material of the conductive metal plate 31 is placed in a molding die (not shown), a predetermined amount of carbon powder is charged into the die, and the portions indicated by hatching in FIG. To form the original shape of the commutator piece 51. During the formation of the powder compact, a plurality of coupling projections 51c are integrally formed on the lower surface of the commutator piece 51. Then, the commutator piece 51 and the metal plate 3 are placed in a firing furnace or the like, and the carbon powder formed into the powder is fired. When forming the green compact, the metallic powder or the mixed powder of the metal and the carbon may be sequentially formed from the periphery of the metal plate 3 in the order of increasing mixing ratio of the metal powder and the multilayer.

In the next step, each strip 31 of the metal plate 31 is
The connecting portions 32 and 33 connected to the outer end and the center end of the cutting line 6c are cut by a suitable press into a cutting line 6 indicated by a two-dot chain line in FIG.
From each other to separate each strip 31c. At this time, the strips 31c are connected to each other by the commutator pieces 51 formed by powder compaction. From this state, each strip 3
A riser piece 31a at the tip of 1c and a plurality of claws 3b protruding from the inner periphery are bent and formed to predetermined dimensions.

Thereafter, the intermediate product is placed in a molding die (not shown) so that the outer surfaces of the plurality of riser pieces 31a are exposed, and a synthetic resin having electrical insulation is used in the same manner as in the above-described example. The boss 2 is insert-molded. At the center of the boss 2 during this insert molding,
A shaft hole 21a for fitting and fixing to a rotating shaft of a fuel supply pump motor (not shown) is formed in the axial direction. At this time, the claws 31b protruding from the metal plate 3 and the coupling protrusions 51c formed on the lower surface of the commutator piece 51 are connected to the boss 2b.
By burying it inside and engaging with resin, the commutator piece 5
The connection between the boss 1 and the boss 2 is strengthened as in the above-described example.

Thereafter, as shown in FIG. 6, the distal ends of the plurality of riser pieces 31a are bent into a U-shape. Further, slits 41 are formed at regular intervals in the circumferential direction between the commutator pieces 51 and the conductive metal plate 31 using a slicer such as a cutting grindstone. As a result, each commutator piece 51 and the conductive metal plate 31 are made independent from each other in a state of being electrically insulated through the slit 41, but are connected to each other by the boss portion 2. Also in this second embodiment, the riser piece 3
An exposed portion such as the outer peripheral surface of 1a may be plated with tin or the like to form a protective film for preventing copper as a base material from eroding alcohol or a crude component in gasoline.

In the above-described embodiments, in both embodiments, not only the two-layer structure of the sliding layer and the metal conductive layer, but also the transition from the sliding layer on one side to the metal conductive layer on the other side sequentially. Thus, the present invention is not limited to the embodiments of the present invention, such as making the boundary between the two layers unclear, and can be appropriately changed without departing from the present invention.

[0035]

As described above, in the present invention, a plurality of commutator pieces are formed into a conductive metal plate by carbon powder and are formed integrally by sintering. In this method, a powder metallurgy method whose mass production technology has already been established can be adopted, and a commutator with high reliability and high quality can be formed at low cost. Further, when the commutator piece is formed of carbon, chemical resistance is improved and chemical stability is excellent, so that the gasoline itself can be prevented from being reformed without being affected by alcohol or the like in gasoline. Furthermore, if a carbon brush is combined with the sliding layer of the commutator piece made of carbon,
Abrasion resistance can be improved because of the same material. Further
Also, the outer and inner peripheral parts of the commutator piece are
By enclosing the motor,
Prevent accidents such as damage to commutator pieces during the assembly process
Can prevent the mechanical strength can be increased
You. In addition, a conductive metal plate and a wire of a conductive layer to be joined thereto are provided.
By approximating or equalizing the coefficient of expansion,
Peeling and cracking that are likely to occur due to shrinkage of
Problems can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a carbon commutator of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a plan view showing an original shape of a conductive metal plate.

FIG. 4 is an explanatory view showing a state of an intermediate step in which a commutator piece is subjected to compacting and sintering.

FIG. 5 is an explanatory diagram showing a state of an intermediate step of forming a boss portion from FIG. 4;

FIG. 6 is a sectional view showing a second embodiment of the carbon commutator of the present invention.

FIG. 7 is a plan view of FIG.

FIG. 8 is a plan view showing an original shape of a conductive metal plate in a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carbon commutator 2 Boss part 2c Shaft hole 3 Conductive metal plate 3a Riser piece 3b Claw 3c Through hole 4 Slit 5 Commutator piece 5c Coupling projection

Claims (2)

(57) [Claims] 1. A plurality of commutator pieces arranged flat through slits, and a plurality of conductive metal plates each joined to the commutator pieces and formed with a riser piece in a radial direction, A rectifier having at least the metal plate and a boss portion made of an electrically insulating synthetic resin having a shaft hole formed at the center and having a central hole, wherein the plurality of commutator pieces are made of carbon powder, This carbon powder is formed into a single body by sintering while simultaneously compacting the carbon powder onto the metal plate, and annular ridges are formed on the outer periphery and the inner periphery of the upper surface of the boss.
Is formed, and the above arrangements are placed in the recess surrounded by the jetty.
A carbon commutator characterized by containing a sprinkle piece and each conductive metal plate. 2. A linear expansion of a conductive layer bonded to a conductive metal plate.
The coefficient is higher than that of the commutator piece made of carbon powder.
Approximate or equal to the linear expansion coefficient of the reactive metal
The carbon commutator according to claim 1 .