JP2003221605A - Sintered alloy, manufacturing method therefor and motor type fuel pump with bearing consisting of sintered alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered alloy which has superior corrosion resistance and can assure dimensional accuracy of the product. <P>SOLUTION: This manufacturing method comprises compacting and sintering (S2) a base powder containing copper into a main body of the sintered alloy, plating (S4) the main body with tin, and sizing it (S5). At the sizing step, the tin plated layer is compressed to form the thickness approximately uniform, and simultaneously the pores which open to the outer surface of the main body are blocked with the tin plated layer. Moreover, combining a copper-base sintered alloy with tin plating gives the sintered alloy corrosion resistances both to sulfur and compounds thereof, and to organic acids such as formic acid and acetic acid. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered alloy, a manufacturing method thereof, and a motor type fuel pump using a bearing made of a sintered alloy.

[0002]

Conventionally, it is known that a motor type fuel pump for a gasoline engine has a structure illustrated in a schematic sectional view in FIG. That is, as shown in the figure, the fuel pump 1
A rotating shaft 4 fixed to both ends of the motor 3 is supported by a bearing 5, an impeller 6 is inserted into one end of the rotating shaft 4, and the impeller 6, the outer peripheral surface of the motor 3 (armature), and It has a structure in which a gasoline flow passage 7 having a narrow gap is formed along a gap (not shown) between the bearing 5 and the rotary shaft 4, and the impeller 6 rotates by the rotation of the motor 3.
The gasoline is taken into the casing 2 by the rotation of the impeller 6, and the taken gasoline is formed along the impeller 6, the outer peripheral surface of the motor 3, and a gap (not shown) between the bearing and the rotating shaft. It is sent out through the road 7 and is operated so as to be sent to a separately installed gasoline engine. In FIG. 8, a small amount of fuel passes through the outer peripheral portions of both bearings 5 and 5, and the gasoline whose pressure is increased by impeller 6 reaches the outer peripheral surface of motor 3 through gasoline passage 7 of casing 1.

Bearing 5 which is a structural member of the above fuel pump
A copper-based sintered alloy is used for this, and in the production of this sintered alloy, a raw material powder containing copper is compressed to form a green compact, and the green compact is sintered and fire-bonded. Forming the gold body,
This sintered alloy body is subjected to sizing, which is recompression, to finish it to a predetermined size.

Since the bearing 5 is used in an environment exposed to fuel, a copper-based sintered alloy using a raw material powder containing copper is used in consideration of corrosion resistance to fuel. Has been. However, even with such a copper-based sintered alloy, if a fuel mixed with sulfur or its compound or a fuel mixed with an organic acid such as formic acid or acetic acid is used, there is a problem that the life is shortened due to corrosion.

Therefore, in the copper-lead alloy bearing disclosed in JP-A-5-202938, in order to improve the corrosion resistance of the bearing, the inner and outer surfaces of the copper-lead alloy bearing are plated with tin, lead or an alloy thereof. It is effective to apply (Patent Publication No. 0005)
Dan).

However, for a product requiring a dimensional accuracy of 10 μm or less, for example, even if the product is within the dimensional tolerance due to the sizing before the plating treatment, the dimensional accuracy cannot be ensured due to the variation in the thickness of the plating layer applied thereafter. There's a problem.

The present invention is intended to solve such a problem, and is a sintered alloy having excellent corrosion resistance and capable of ensuring dimensional accuracy of a product, a method for producing the same, and a bearing made of the sintered alloy. An object of the present invention is to provide a motor-type fuel pump using.

[0008]

A sintered alloy according to claim 1 is
In order to achieve the above object, a tin alloy layer is provided on a sintered alloy body obtained by molding and sintering a raw material powder containing copper, and the sintered alloy body having the tin plated layer is sized. It is a thing.

By covering the copper-based sintered alloy body with a corrosion-resistant tin-plated layer, a sintered alloy having high corrosion resistance can be obtained. In particular, the combination of a copper-based sintered alloy and tin plating provides both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid. Further, since the sintered alloy body having the tin-plated layer is sized, the product dimension including the tin-plated layer can be finished within a predetermined dimensional tolerance. Moreover, the tin-plated layer is compressed by sizing to form the tin-plated layer with a substantially uniform thickness, and at the same time, the compressed tin-plated layer seals the pores on the outer surface of the sintered alloy body.

According to the invention of claim 2, in the sintered alloy of claim 1, the sintered alloy is a sliding member.

A sliding component having both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid can be obtained.

In order to achieve the above object, in the method for producing a sintered alloy according to claim 3, a raw material powder containing copper is molded and sintered to form a sintered alloy body. It is a method of sizing after tin plating.

By using this method, the tin-plated layer is compressed during sizing, and the tin-plated layer is formed to have a substantially uniform thickness. At the same time, the tin-plated layer is compressed by the sizing and baked and bonded by the tin-plating. Since the pores that open to the outer surface of the gold body are closed, the compressed tin plating layer seals the pores on the outer surface of the sintered alloy body, and the coverage with the tin plating layer is improved.
Further, since the sintered alloy body having the tin-plated layer is sized, the product dimension including the tin-plated layer can be finished within a predetermined dimensional tolerance. Moreover, by combining a copper-based sintered alloy and tin plating, a sintered alloy having both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid can be obtained.

A motor type fuel pump according to a fourth aspect uses the bearing made of the sintered alloy according to the first aspect.

As a result, the bearing of the motor type fuel pump has an excellent life even with fuel containing sulfur or its compound or organic acids such as formic acid and acetic acid.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show an embodiment of the present invention, in which Cu-Ni-Zn- is used as a raw material for the sintered alloy body.
C-based or Cu-Sn-C-based materials can be used. The bearing 5 will be described below as an example of a sintered alloy. As shown in FIGS. 2 and 3, the bearing 5 is composed of a substantially cylindrical sintered alloy body 51, and a cylindrical sliding surface 52 on which the rotary shaft 4 is rotationally slid is formed in the center thereof. Further, a tin-plated layer 53 covering all exposed outer surfaces of the sintered alloy body 51.
Equipped with. In the present invention, tin plating includes plating of tin or tin alloy.

As an example, the sintered alloy body 51 of the bearing 5 has a mass% of Zn: 10 to 25% and Ni: 10 to 2
5%, P: 0.1 to 0.9%, C: 1 to 8%, with the balance being Cu and inevitable impurities, and 5
A graphite-dispersed Cu-based sintered alloy having a porosity of ˜25% can be used, and a graphite-dispersed Cu-based sintered alloy having another composition can also be used.

The manufacturing method will be described with reference to FIG. 1. For example, as the raw material powder used for the sintered alloy main body 51, all are formed by the water atomizing method and 45
Five kinds of Cu-Ni-Zn alloy powders having an average particle diameter of μm, that is, Cu-15.8% Ni-18.3% Zn
Alloy powder, Cu-16.9% Ni-18.0% Zn alloy powder, Cu-18.8% Ni-18.4% Zn alloy powder, Cu-17.4% Ni-16.4% Zn alloy powder ,
And Cu-17.3% Ni-19.9% Zn alloy powder (above 5 types), water atomized Cu-P alloy (containing P: 33%) powder having an average particle diameter of 45 μm, and further 75
After preparing a graphite powder having an average particle size of μm, blending these raw material powders into a predetermined blending composition, and performing mixing for 40 minutes with a V-type mixer (S1: step 1),
A green compact having a predetermined shape is formed (S2) by a press at a predetermined pressure within a range of 150 to 300 MPa, and the green compact is heated to a predetermined temperature within a range of 750 to 900 ° C. in an ammonia decomposing gas atmosphere. By sintering (S3) under the condition of holding for a minute, a bearing 5 made of a graphite-dispersed Cu-based sintered alloy was manufactured. When the bearings 5 obtained as a result were observed using an optical microscope (200 ×), they were all Cu-
The structure was such that the Cu-P alloy and graphite were finely distributed and distributed in the base material composed of the solid solution phase of the Ni-Zn alloy, and pores were also present. The thus-obtained graphite-dispersed Cu-based sintered alloy bearing 5 is made of Cu-Ni- which forms the base material.
Combined with the excellent strength and corrosion resistance of Zn alloys,
It has excellent wear resistance under the environment exposed to high pressure and high speed flow of gasoline.
A motor-type fuel pump using a base sintered alloy bearing has an excellent life even for a fuel containing sulfur or its compound as an impurity.

In the present invention, in order to further improve the corrosion resistance, after the sintering (S3) process, the sintered alloy body 51 is plated (S).
4) Perform processing. In this plating (S4) process, a plating layer 53 containing tin (Sn) having a thickness of about 2 to 25 μm is formed on the outer surface of the sintered alloy body 51 by an electroplating method or the like.

After the plating treatment, the bearing 5 is recompressed and sized (S5) to finish it to a predetermined size. As an example, FIG. 4 shows a straightening die apparatus 11 used for sizing. This straightening die apparatus 11 has a vertical direction as an axial direction (press vertical axis direction), and includes a die 12, a core rod 13, and a lower punch 14.
And has an upper punch 15. The die 12 has a substantially cylindrical shape, and a substantially cylindrical core rod 13 is coaxially positioned inside the die 12. The lower punch 14 has a substantially cylindrical shape, and is fitted between the die 12 and the core rod 13 so as to be vertically movable from below. The upper punch 15 has a substantially cylindrical shape, and is fitted between the die 12 and the core rod 13 so as to be vertically movable and removable from above. Then, as shown in FIG. 4, the die 5 is filled with the bearing 5, and the core rod 13 is inserted and arranged in the sliding surface 52, which is a through hole of the bearing 5. , 14 to pressurize the bearing 5 to correct it to a predetermined size.

Here, in order to confirm the states of the tin-plated layer 53 before sizing and the tin-plated layer 53 after sizing, a plurality of sintered alloy main bodies 51 were produced and an enlarged photograph of the structure was taken. In practice, 20 sintered alloy bodies 51 were formed under the same conditions until the plating treatment, and then half of the 10 sintered body bodies 51 were sized.

Then, the ten sintered alloy bodies 51 were cut as shown in FIG. 3, and an enlarged photograph of the structure of the sliding surface 52 was taken. This did not size it 10
In the individual sintered alloy body 51, the tin-plated layer 53 on the sliding surface 52
The average thickness of the tin-plated layers 53 on the sliding surface 52 was about 6 μm in the 10 sintered alloy bodies 51 sized. When the sizing is performed in this way, the thickness of the tin-plated layer 53 becomes thin and the tin-plated layer 53 is stretched.
The opening 54A of 54 is closed.

Sintered alloy body 51 without sizing
Then, as shown in FIG. 5, there is a pore 54 having an opening 54A in the sliding surface 52, which is a portion where the sealing by plating is insufficient. Further, irregularities are seen on the outer surface of the tin-plated layer 53, and these irregularities are formed by the variation in the thickness of the tin-plated layer 53.

On the other hand, in the sintered alloy body 51 that has been sized, as shown in FIG. 6, the openings 54A of the pores 54 opening in the sliding surface 52 are closed by the tin plating layer 53, and at the same time, The outer surface of the tin-plated layer 53 also had little unevenness.

By performing the sizing (S5) after the plating as described above, the tin-plated layer 53 is compressed and spread out, and the tin-plated 53 closes the pores 54 opening to the outer surface of the sintered alloy body 51. Coverability with the tin-plated layer 53 is improved. Moreover, the outer surface of the tin-plated layer 53 can be made flat by sizing (S5) and finished to have a substantially uniform thickness.

As described above, in the present embodiment, according to claim 1, the tin-plated layer 53 is provided on the sintered alloy body 51 formed by molding and sintering the raw material powder containing copper. Since the bearing 5 having the plated layer 53 is sized, by covering the copper-based sintered alloy body 51 with the corrosion-resistant tin-plated layer 53, the sintered alloy bearing 5 having high corrosion resistance can be obtained. .

In particular, the combination of a copper-based sintered alloy and tin plating provides both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid. Further, since the sintered alloy body 51 having the tin-plated layer 53 is sized, the product dimension including the tin-plated layer 53 can be finished within a predetermined dimensional tolerance. Moreover, the tin-plated layer 53 is compressed by sizing, and the tin-plated layer 53 is formed to have a substantially uniform thickness. At the same time, the compressed tin-plated layer 53 is formed.
Seals the pores on the outer surface of the sintered alloy body 51 and has excellent coverage with the tin-plated layer 53.

As described above, in this embodiment, according to claim 2, the sintered alloy is the bearing 5, which is a sliding member, and has corrosion resistance to sulfur and its compounds and organic acids such as formic acid and acetic acid. The bearing 5 having both corrosion resistance can be obtained.

As described above, in this embodiment, according to the third aspect, the raw material powder containing copper is molded and sintered to form the sintered alloy body 51, and the sintered alloy body 51 is tinned. Since sizing is performed after plating, the tin plating layer 53 is compressed during sizing, and the tin plating layer 53 is formed to have a substantially uniform thickness, and at the same time, the tin plating layer 53 is compressed by the sizing and the tin plating layer 53 is compressed. Since the pores 54 opening to the outer surface of the sintered alloy body 51 are closed by 53, the compressed tin plating layer 53 seals the pores on the outer surface of the sintered alloy body 51, and the tin plating layer 53 improves the coverage. Further, since the sintered alloy body 51 having the tin-plated layer 53 is sized, the product dimension including the tin-plated layer 53 can be finished within a predetermined dimensional tolerance. Moreover, by combining a copper-based sintered alloy and tin plating, a sintered alloy having both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid can be obtained.

As described above, in this embodiment, since the bearing 5 made of the sintered alloy according to claim 1 is used in accordance with claim 4, the bearing 5 of the motor type fuel pump uses sulfur or its compound, Alternatively, it has an excellent life even for a fuel containing an organic acid such as formic acid or acetic acid.

FIG. 7 shows a second embodiment of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. S3)
By performing sizing (S6) before plating the sintered alloy body 51 obtained by the treatment, the sintered alloy body 51 is finished to a predetermined size, and then the plating (S4) treatment is performed to perform the plating (S4). The sizing (S5) is performed after the treatment, and the sizing (S6), which is recompression, is performed on the sintered alloy main body 51 before the plating treatment, whereby a sintered alloy having higher dimensional accuracy can be manufactured.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, the present invention can be applied to various materials as long as the raw material powder contains copper or a copper alloy. Further, the bearing is not limited to that of the embodiment, and various shapes can be applied.
Further, the sliding member is not limited to the bearing, and can be applied to various sliding members as long as it has a sliding portion.

[0033]

According to the sintered alloy of claim 1, a sintered alloy body obtained by compacting and sintering a raw material powder containing copper,
A tin-plated layer is provided, and a sintered alloy body having this tin-plated layer is sized, and a sintered alloy having both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid is obtained. can get. Further, since the sintered alloy body having the tin-plated layer is sized, the product dimension including the tin-plated layer can be finished within a predetermined dimensional tolerance.

In addition to the effect of claim 1, the invention of claim 2 is that the sintered alloy is a sliding member,
A sliding part having both corrosion resistance to sulfur and its compounds and corrosion resistance to organic acids such as formic acid and acetic acid can be obtained.

According to a third aspect of the present invention, in a method for producing a sintered alloy, raw material powder containing copper is molded and sintered to form a sintered alloy body, and the sintered alloy body is tin-plated and then sized. In the method, the tin plating layer is compressed during sizing, and the tin plating layer is formed to have a substantially uniform thickness. At the same time, the tin plating is compressed by the sizing and applied to the outer surface of the sintered alloy body by the tin plating. Since the pores that open are closed, the compressed tin plating layer seals the pores on the outer surface of the sintered alloy body, and the coverage with the tin plating layer is improved.

A motor type fuel pump according to a fourth aspect of the invention uses a bearing made of the sintered alloy according to the first aspect of the invention, and is suitable for fuels containing sulfur and its compounds, or organic acids such as formic acid and acetic acid. It has an excellent life.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the sintered alloy body.

FIG. 3 is a cross-sectional view of a partially expanded sintered alloy.

FIG. 4 is a sectional view explaining sizing of the above.

FIG. 5 is an enlarged cross-sectional view of the tin-plated layer before sizing as above.

FIG. 6 is an enlarged cross-sectional view of the tin-plated layer after sizing as above.

FIG. 7 is a flowchart illustrating a manufacturing method according to the second embodiment of the present invention.

FIG. 8 is a schematic sectional view of a motor type fuel pump for a gasoline engine.

[Explanation of symbols]

1 Bearing (sintered alloy) 51 Sintered alloy body 52 Sliding surface 53 Tin plating layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) C22C 9/06 C22C 9/06 C25D 7/00 C25D 7/00 C 7/10 7/10 F02M 37/08 F02M 37/08 EZ F04D 29/02 F04D 29/02 F16C 33/12 F16C 33/12 Z 33/14 33/14 A (72) Inventor Tsuneo Maruyama 3-1-1 Koganecho, Niigata City, Niigata Prefecture Mitsubishi Material Co., Ltd., Niigata Works (72) Inventor, Daimei Takei, 1-1, Showa-cho, Kariya, Aichi Prefecture, Denso, Inc. (72) Inventor, Yoichi Murakami, 1-1, Showa-cho, Kariya, Aichi, Ltd., Denso, Inc. F term (reference) 3H022 AA01 BA06 CA11 CA51 DA14 DA19 3J011 AA20 BA02 CA05 DA01 DA02 JA02 KA02 LA01 MA02 MA12 QA03 SB05 SB19 4K018 AA04 FA02 FA23 KA03 4K024 AA07 BA09 BB04 BB05 B C07 BC10 DB07 GA04

Claims (4)

[Claims] 1. A tin-plated layer is provided on a sintered alloy body obtained by molding and sintering a raw material powder containing copper, and the sintered alloy body having the tin-plated layer is sized. And sintered alloy. 2. The sintered alloy according to claim 1, wherein the sintered alloy is a sliding member. 3. A sintered alloy body, characterized in that a raw material powder containing copper is molded and sintered to form a sintered alloy body, and the sintered alloy body is tin-plated and then sized. Production method. 4. A motor-type fuel pump using the bearing made of the sintered alloy according to claim 1.