JP2007032576A - Fuel pump for cylinder direct fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump for a cylinder direct fuel injection device capable of preventing occurrence of corrosion, cavitation, and wear due to erosion even at high temperatures reaching 100°C or more and even under high pressures reaching 7 to 12 MPa and improving resistance to the environment and having excellent service life when using an aluminum material. <P>SOLUTION: A Ni-P or Ni-P system plated film is formed by electroless plating in the fuel feed pump in the cylinder direct fuel injection device having aluminum or aluminum alloy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel pump used for an in-cylinder direct fuel injection device of an automobile.

  In-cylinder direct fuel injection devices are used in gasoline engines for automobiles for the purpose of improving fuel consumption characteristics, reducing harmful exhaust gases, and improving driving responsiveness such as acceleration.

  From the viewpoint of energy saving by reducing the weight of the automobile, a product that is made lighter by applying an aluminum-based material to the fuel pump member of the in-cylinder direct fuel injection device is desired.

  Japanese Patent Application Laid-Open No. 7-48681 describes a technique in which a metal film is formed on aluminum or an aluminum alloy by electroless plating, followed by electroplating.

JP 7-48681 A

  However, since the technique described in Japanese Patent Application Laid-Open No. 7-48681 uses electroplating in addition to electroless plating, if applied directly to an in-cylinder direct fuel injection device having a large number of holes and narrow gaps, An area where a film is not formed is formed at a location where the flow is poor, and the problem remains that the substrate is exposed to cause damage such as corrosion.

  As described above, an object of the present invention is to provide a fuel pump for an in-cylinder direct injection device having an excellent life using an aluminum material.

  As means for achieving the above object, the present invention forms a Ni-P or Ni-P plating film on a fuel pump in an in-cylinder direct fuel injection device having aluminum or an aluminum alloy. As a result, even under high temperatures reaching 100 ° C. or higher and high pressures reaching 7-12 MPa, aluminum and aluminum alloys are also prevented from corrosion, cavitation and erosion due to alcohol contained in gasoline, A fuel pump having excellent high reliability can be realized.

  According to the present invention, a fuel pump for an in-cylinder direct injection device having an excellent life using an aluminum material can be provided.

[Example 1]
In this embodiment, Ni-P plating is applied to a radial plunger fuel pump (one cylinder type).

  Before describing one embodiment of the present invention, first, problems that occur in a fuel pump when aluminum or an aluminum alloy is used as the material of the fuel pump body will be described.

(1) Problem of corrosion of aluminum In this embodiment, aluminum used as a material for a fuel pump forms a protective oxide film Al ₂ O ₃ on the outermost surface. It exists stably.

  However, when alcohol, moisture, acid components, etc. are mixed in gasoline, the corrosion of the material may be accelerated. For example, the presence of alcohol is thought to corrode aluminum.

For example, when ethanol, which is alcohol, is specifically described as an example, aluminum and ethanol are
2Al + 6C ₂ H ₅ OH → Al (OC ₂ H ₅ ) ₃ + 3H ₂
To react. This produces Al (OC ₂ H ₅ ) ₃ , which is unstable and immediately Al (OC ₂ H ₅ ) ₃ + 6H ₂ → 2Al (OH) ₃ + 6C ₂ H ₆
2Al (OH) ₃ → Al ₂ O ₃ .H ₂ O + 2H ₂ O
It will be decomposed by the reaction.

That is, the thin Al ₂ O ₃ barrier layer formed by the above reaction is immediately damaged by ethanol at a high temperature, and the corrosion of the aluminum base material without the barrier layer proceeds, resulting in wear. In addition, the reaction rate increases as the temperature increases. Specifically, in a fuel passage system component exposed to a temperature range of 100 ° C. or higher, the corrosion reaction due to alcohol is accelerated at a stroke. In addition, since the pressure reaches a high pressure of 7 to 12 MPa in the pressurizing chamber of the fuel pump, the reaction speed is accelerated at once.

(2) Problem of wear due to cavitation Cavitation is caused by bubbles generated from a pressure difference in the pump. That is, a high pressure flow rate of 7 to 12 MPa or more is generated in the pressurizing chamber in the fuel chamber, while a low pressure flow rate exists in the corner of the pump portion. This leads to the generation of bubbles and results in significant damage to the pump. That is, the problem of cavitation becomes a very big problem in a fuel flow path in which fuel flows at high pressure. The degree of wear due to cavitation also affects the hardness of the base material, and wear due to cavitation becomes even more pronounced with aluminum materials that are soft materials.

(3) Problem of wear due to erosion (erosion) In the pump part (pressure chamber) in the fuel chamber, a high pressure of 7 to 12 MPa or more is generated as described above. Therefore, erosion (erosion) of the fuel flow path by the high-speed fluid becomes a significant problem, and this influence must be taken into consideration. In particular, the influence of erosion becomes significant in a complicated and narrow portion such as a joint portion of a fuel flow path in which the fuel flow changes in the fuel chamber.

  The above problems (1) to (3), that is, damage due to corrosion, cavitation and erosion may cause the fuel pump to stop operating. Therefore, each part made of aluminum material in the fuel flow path parts for fuel supply is composed of a fuel containing various alcohols, a fuel mixed with water, a fuel mixed with oxidizing components, or a deteriorated fuel. Durability is required in an environment that comes into contact with the inside.

  Next, the Ni-P plating process of the radial fuel pump and the manufacturing method of the radial plunger fuel pump will be described.

  FIG. 1 shows a cross-sectional shape of a pump body made of an aluminum alloy. The pump body is provided with a fuel intake passage, a fuel discharge passage, a fuel flow passage hole, an engine body fixing bolt hole, and the like. In order to become a fuel pump, a suction damper, a solenoid for controlling the discharge amount, and a pump mechanism (cylinder, plunger) are incorporated in the pump body.

First, it is necessary to manufacture this pump body. Since it is inferior in productivity to manufacture all of these shapes by machining, there is aluminum die casting as a manufacturing method excellent in the productivity of the general shape (as cast) of the pump body. Aluminum die casting is a casting method in which a molten alloy (aluminum alloy) is pressurized and injected into a die at a high pressure, and is excellent in mass productivity. The manufacturing process by aluminum die casting is aluminum alloy ingot → melting → casting → material (as cast) → machining finish → pump body. In this process, the pump body material (as
cast) is shaped to minimize machining allowances. As the aluminum alloy in this case, for example, 12 types of aluminum alloy die casting (ADC12) are used. Depending on the type of aluminum alloy, the final shape of the pump body is manufactured by machining after forging or all machining.

  Next, a Ni-P or Ni-P plating film is formed on the pump body manufactured by the above process.

  In this embodiment, these plating films are Ni-P or Ni-P. The Ni-P type is not particularly limited as long as it is a material that can be alloyed or dispersed with a plating film, such as metallic elements Co, W, inorganic compounds SiC, BN, PTFE, inorganic B, and the like. Absent.

  The Ni—P and Ni—P plating films of the plating film 501 are desirably formed by an electroless method. That is, the fuel flow path has a complicated and narrow portion, and it is essential that a coating is formed in any of these portions, and the thickness of the plating coating needs to be formed as uniformly as possible. It depends on things. The plating method using electric energy is not desirable because the plating film cannot be formed in the complicated and narrow fuel flow path due to the non-uniformity of the electric field distribution due to the shape effect, or it may become non-uniform even if it can be formed. Because.

  Here, in the electroless Ni-P plating, when the hypophosphite anion in the plating solution comes into contact with the eighth group metal in the periodic table, the metal serves as a catalyst to cause dehydrogenative decomposition. The generated hydrogen atoms are adsorbed on the catalytic metal surface and activated as a condensed layer, which comes into contact with the nickel cation in the plating solution to reduce nickel to metal and deposit on the catalytic metal surface (base material). . The activated hydrogen atoms on the surface of the catalytic metal react with the hypophosphite anion in the liquid, and the phosphorus contained therein is reduced to form an alloy with nickel. The deposited nickel is used as a catalyst to continue the above-described nickel reduction plating reaction. That is, there is a feature that the plating proceeds continuously by the autocatalytic action of nickel. Thereby, if there is a gap through which the plating solution flows, a plating film is uniformly formed. Further, the thickness of the plating film is proportional to the plating time and is managed by controlling the time.

  In the formation process of the Ni-P or Ni-P plating film, it is essential that the plating film is uniformly formed on the entire surface of the pump body. Therefore, in the plating process, it is important that the entire surface of the pump body is in contact with the plating solution and that the plating solution circulates without stagnation.

  In order for the entire surface of the pump body to come into contact with the plating solution, it must be arranged (how to suspend) at least in various holes related to the fuel flow path of the pump body, and an important part of the pump body It is useful that all the various holes formed as the fuel flow path are through holes. In addition, even if it is a through hole, if there is a so-called blind hole (a hole in which another hole is formed in the vicinity of the center of the flow path, not in the vicinity of the short part of the flow path (see FIG. 2B)), the plating solution Therefore, it is very useful to form a uniform plating film by connecting each hole near the short part of each hole (see FIG. 2A) to eliminate the retention of the plating solution. .

  Circulating the plating solution on the entire surface of the pump body without stagnation is indispensable for continuing the precipitation by Ni-P or Ni-P autocatalysis. When the stagnation occurs, precipitation due to autocatalysis within a limited amount of plating solution ends, and subsequent deposition stops, and the increase in the thickness of the plating film stops. Therefore, the film thickness is nonuniform. In order to prevent such a situation, as a method of circulating the plating solution on the entire surface of the pump body without stagnation, movement of the pump body in the plating solution, for example, up / down, left / right, and rotational movement, to fluidize the plating solution To do.

  As described above, contact with the plating solution on the entire surface of the pump body and retention of the plating solution can be prevented, and an excellent plating film with few uniformity and defects can be formed on the entire surface of the pump body.

  In this example, an aluminum alloy casting material ADC12 was used, and a Ni—P plating film having a thickness of 15 μm (thickness distribution ± 2 μm) was formed on the entire surface of the pump body 100. Further, the P concentration of the Ni—P plating solution was about 11 wt.

  3 to 6 show examples of the surface structure of the fuel pump.

  FIG. 3 shows a surface structure in which a plating film 501 is provided on a base 500 of an aluminum alloy.

  FIG. 4 shows a surface structure in which a plating film 501 and an intermediate layer 502 are provided on an aluminum alloy substrate 500.

  FIG. 5 shows a surface structure in which a plating film 501 and an outer layer 503 are provided on an aluminum alloy substrate 500.

  FIG. 6 shows a surface structure in which a plating film 501 and an outer layer 503 are coated with a defect portion such as a hole in the plating film 501 on an aluminum alloy substrate 500.

  The intermediate layer 502 has a function of improving adhesion with the plating film 501 or improving corrosion resistance. Ni is used for the intermediate layer 502 for improving the adhesion. For the function of improving the corrosion resistance, an oxide film or a chromate film is used. The oxide film is preferably a dense film formed in high-temperature and high-pressure water.

  The outer layer 503 has a function of improving the corrosion resistance of the plating film 501. The material is a chromate film.

  The sealing layer 504 has a function of sealing defects of the plating film 501 and improving corrosion resistance. The material used is an oxide film or a chromate film. The oxide film is preferably a dense film formed in high-temperature and high-pressure water.

  Furthermore, in this embodiment, a heat treatment is applied to the film formed by electroless plating to increase the hardness of the film, improve the adhesion between the substrate and the film, and improve the cavitation resistance. Details of this will be described later. The plating film was heat-treated at 200 ° C. for 1.5 hours in the air. As a result, the hardness of the Ni-P plating film increased from Hv520 to Hv600 as it was.

Next, the radial plunger fuel pump of the present embodiment produced by the above manufacturing method will be described with reference to FIG. 7 (sectional view). The Ni—P plating is uniformly applied to the pump body 100 made of an aluminum material by the above-described processing. In this embodiment, an aluminum material is used as a part of the fuel pump that comes into contact with the fuel. In the pump body 100, the pressurizing chamber 112, the fuel suction passage 110, the pressurizing chamber 112, the fuel discharge passage 111, etc., methyl alcohol, ethyl It is assumed to be used in contact with gasoline containing alcohol, such as alcohol, various gasoline additives, or deteriorated gasoline (of course, the use of gasoline-only fuel is not denied).

In the pump body 100, a fuel suction passage 110, a suction hole 105a, a pump chamber 112a, a discharge path 106a, and a fuel discharge passage 111 are formed as fuel flow paths. The intake valve 105 is provided between the fuel intake passage 110 and the intake hole 105a, and the discharge valve 106 is provided between the fuel discharge passage 111 and the discharge well 106a. Here, both the intake valve 105 and the discharge valve 106 are check valves that limit the flow direction of fuel. The pressurizing chamber 112 includes a pump chamber 112a, a suction hole 105a, and a discharge port 106a. That is, the pressurizing chamber 112 is formed as a region surrounded by the pump body 100, the plunger 102, the suction valve 105, and the discharge valve 106. The plunger 102 is in pressure contact with the drive cam 200 via the lifter 103, and is configured to convert the swinging motion of the drive cam 200 into a reciprocating motion so that the volume of the pressurizing chamber 112 changes.

On the other hand, the pump body 100 and the suction valve holder 105b, the pump body 100 and the discharge valve holder 106b are in pressure contact with each other, and the cylinder 108 and the pump body 100 are also in pressure contact with each other via the protector 120. The protector 120 is useful for preventing the base material such as the pump body from being damaged due to the occurrence of cavitation (described later), and whether or not the protector 120 is used is selected according to the use condition of the pump. Further, although the protector 120 is intentionally provided in this embodiment, it is possible to select not to use the protector 120 as long as the Ni-P plating can be made thick and sufficient corrosion resistance and cavitation resistance can be achieved. . In addition, in the radial plunger fuel pump of this embodiment, since the pump body is Ni-P plated, the soft aluminum generated when the protector 120 (including the pressure contact member such as the cylinder 108, etc.) is pressed. The direct contact between the base material and the protector 120 can be suppressed, and the generation of powder of the soft base material that occurs during the press contact can also be suppressed. Furthermore, in this embodiment, the pump body is made of an aluminum material, and the member to be pressed is a member having higher hardness (for example, SUS304), so that the pressure contact member can be bitten to improve the sealing performance. By providing an intermediate hardness Ni-P plating layer between the aluminum material and the high-hardness pressure contact member, it becomes possible to prevent deformation of the aluminum material larger than necessary in the pressure contact. Needless to say, the protector 120 can be used for other press contact portions, and naturally the same effect as described above can be obtained.

  Here, the operation of the radial plunger fuel pump of this embodiment will be briefly described.

  Fuel gasoline is supplied via the suction valve 105 and introduced into the pressurizing chamber 112. Here, the suction valve 105 depends on the operation of the solenoid 300. When the solenoid 300 is in an OFF (non-energized) state, a biasing force is applied in a direction to open the suction valve 105, and when the solenoid 300 is in an ON (energized) state. Is a free valve that opens and closes the intake valve 105 in synchronization with the reciprocating motion of the plunger 102. When the suction valve 105 is closed during the compression process of the plunger 102, the internal pressure of the pressurizing chamber 112 increases, the discharge valve 106 is automatically opened, and the fuel is pumped to the fuel discharge passage.

FIG. 8 shows the corrosion resistance of various materials and an aluminum material plated with Ni-P, which is one surface treatment of the present invention. The corrosion test environment was 13.5 vol.% Ethyl alcohol in water with a total acid value of 0.13.
It was set as the solution of the acid ion concentration of mgKOH / g. FIG. 8 shows the natural potential and the pitting potential in this solution, and shows that the higher the natural potential and the pitting potential, the better the corrosion resistance. It can be seen that SUS304 stainless steel, which is generally used as a material having excellent corrosion resistance, is in a region where the natural potential and pitting potential are high, and has excellent corrosion resistance. On the other hand, the aluminum alloy spread material A1012 having excellent corrosion resistance is in a region where both the natural potential and the pitting potential are lower than that, indicating that the corrosion resistance is inferior. In addition, it can be seen that the aluminum alloy casting material ADC12 is in a lower region, and the corrosion resistance is inferior. In addition, it can be seen that materials such as alloy tool steel SKD11, spheroidal graphite cast iron FCD400, and carbon steel S45C, which are iron-based materials, are also in a low region, the natural potential is higher than that of the aluminum alloy cast material ADC12, and the corrosion resistance is slightly better. From this result, it was found that the aluminum alloy casting material ADC12 is a class of materials having poor corrosion resistance. However, the material in which the ADC12 is subjected to Ni-P plating has significantly higher natural potential and pitting corrosion potential than materials other than SUS, and has excellent corrosion resistance, and is slightly inferior to SUS304 in weight reduction and processing. Therefore, it is a very useful material.

  Next, cavitation resistance was examined. FIG. 9 shows the amount of volume reduction due to cavitation wear of various materials by the magnetostrictive vibration destruction test apparatus.

The measurement in the magnetostrictive vibration destruction test apparatus compares the degree of wear due to cavitation of various materials in pure water having a frequency of 20 kHz, an amplitude of 22.4 μm, and a temperature of 20 ° C. The result of FIG. 9 shows that the volume reduction amount is large in the soft aluminum material system (refer to ADC12 etc.), whereas the volume reduction amount is small in the hard steel, cast iron, and stainless steel. However, when the ADC 12 is subjected to Ni—P plating or Ni—P—SiC plating, the volume reduction amount of the ADC 12 is reduced (see “ADC12 + Ni—P” or the like), which is equivalent to steel or cast iron. From this result, in order to improve the cavitation resistance of the aluminum material system by surface treatment, it was found that Ni-P-based plating was excellent as a surface treatment film. In this case as well, as described above, the invention according to the present embodiment uses an aluminum material as compared with other base materials, and thus has a great advantage in terms of weight reduction and easy processing. I can say that. For cavitation resistance, it is necessary to consider the influence of hardness and film thickness.

  FIG. 10 shows the influence of the heat treatment of the Ni—P plating film on the cavitation wear by the magnetostrictive vibration destruction test apparatus. The hardness of the Ni—P plating film becomes harder by heat treatment. The hardness is about Hv500 with the plating treatment as it is, but it becomes harder as the heat treatment temperature rises, and becomes a high hardness of about Hv1000 at about 400 ° C. In addition, by applying heat treatment to the Ni—P plating layer, the adhesion between the aluminum material and the Ni—P plating layer can be improved, and damage due to cavitation can be suppressed. As seen in FIG. 10, the wear due to cavitation is due to the effect of the increase in hardness and the improvement in adhesion due to heat treatment, and less heat treated at 200 ° C. as compared to as plated. Moreover, FIG. 11 shows the experimental result corresponding to FIG. 9, FIG. 10 performed about the influence of the cavitation to which Ni-P plating was given as a photograph. As can be seen from this figure, the sample subjected to heat treatment at 200 ° C. × 1 hour did not show any damage due to cavitation at 50 minutes or 80 minutes, but the sample without heat treatment was subjected to 50 minutes. Even during the test time, cavitation damage was observed. That is, it shows that the resistance to cavitation is greatly improved by improving the hardness and adhesion of the plating film by the heat treatment. That is, this result shows that it is more effective to heat-treat the plating film in order to improve the cavitation resistance of the Ni-P plating film. However, when the deformation of the fuel pump due to the heat treatment is taken into consideration, it is necessary to carry out at a low temperature. In addition, a higher hardness is desirable for cavitation resistance, but when the heating temperature is increased to harden the plating film, the plating film crystallizes (crystallization temperature: about 220 ° C.), and crystal grains Since the boundary is generated, the alcohol-containing fuel may erode the aluminum base material from the grain boundary, and the corrosion resistance may deteriorate. Therefore, it is useful to prevent the heat treatment from going higher than the crystallization temperature of the Ni—P plating layer and to make the Ni—P plating layer amorphous.

  From the viewpoint of considering the balance between corrosion and cavitation, it is desirable to perform heat treatment at 300 ° C. or lower (Hv is approximately 800), and further heat treatment is performed at a temperature of 220 ° C. or lower (Hv is approximately 650). Is also useful.

In addition, when the thickness of the plating film is 10 μm or less, the plating film may be peeled off due to corrosion, cavitation, etc., and the base may be exposed to cause corrosion before the fuel pump reaches the end of its life. When it is thick, it is useful for corrosion resistance, cavitation resistance, and screw-to-screw hole fitting, but the dimensional difference between the screw hole and screw cannot be ignored, making it difficult to attach the pressure contact parts. As described above, when a uniform plating layer is formed by electroless plating, the thickness of the plating film is desirably about 25 μm in consideration of the above. The reason why the Ni-P plating film is useful for fitting the screw and the screw hole is that even if the surface of the aluminum material is rough, the surface becomes smooth by applying Ni-P plating.
The hardness of the Ni-P plating layer makes the shape of the screw hole more stable than when fitting into the screw hole of the aluminum material without surface treatment, and the aluminum and the pressure contact member when screwing To suppress the generation of aluminum powder due to friction. As long as these are taken into consideration, an electroless plating process capable of plating both the screw hole portion and the fuel passage at a time is very useful.

  In addition, the actual machine durability test of the fuel pump according to this example was also performed. As fuel, gasoline with 22% ethanol added was used, and the test was performed at a rotational speed of 3500 r / min and a discharge pressure of 12 MPa. As a result, the pump operated without any abnormality, and a stable value for gasoline discharge flow rate was obtained. After the test, the result of disassembling and inspecting each part in the fuel chamber, no occurrence of corrosion, wear due to corrosion, or wear in the fuel flow path due to cavitation was observed in any of the above parts. It was in a state. On the other hand, as described above, corrosion and cavitation due to aluminum and ethanol, and wear due to erosion were observed in the untreated material.

  As described above, since the Ni-P or Ni-P plating film is formed in the fuel flow path of the fuel pump in this embodiment, the occurrence of corrosion, cavitation, and further wear due to erosion are suppressed, and their environmental resistance is improved. I was able to. In addition, this makes it possible for the first time to use a fuel pump using aluminum or an aluminum alloy, and a complex-shaped fuel pump can be easily realized. In addition, as long as it is an aluminum material, even if it is aluminum independent and an aluminum alloy, it is natural that there exists an effect of a present Example.

[Example 2]
This example is the same as Example 1 except for the points described below. This will be described with reference to FIG.

  FIG. 12 shows a radial plunger fuel pump having a portion in which an aluminum material is exposed by removing plating from a part of the low-pressure chamber of the pump body that separates the pressurizing chamber and the low-pressure chamber, or by not performing the plating process. As a result, the corrosion resistance of the exposed part of the aluminum material is made the weakest compared to other parts, that is, the low pressure chamber and the pressurizing chamber can be penetrated prior to other corroded parts, resulting from corrosion. Other serious failures can be prevented in a relatively minor situation such as a boost failure.

Example 3
FIG. 13 shows a cross-sectional view of a swash plate type axial plunger fuel pump (3-cylinder type).

  The swash plate type axial plunger fuel pump includes a shaft 1 that transmits drive from outside into a housing, a swash plate 9 that converts rotational motion to swing motion via the shaft, and rotational motion of the swash plate 9 to reciprocating motion. A plunger 11 to be converted and a cylinder bore 13 that is combined with the plunger 11 and sucks and discharges fuel are configured.

  As shown in FIG. 13, the shaft 1 is integrally formed with a swash plate 9 that extends in the radial direction and has an end surface that forms an oblique plane. A slipper 10 is in contact with the swash plate 9, and a taper for assisting oil film formation between the swash plate 9 and the slipper 10 by oil is provided on the outer peripheral portion of the slipper 10 on the swash plate 9 side. The other side of the slipper 10 has a spherical shape, and is supported by a spherical surface formed on the plunger 11 that slides in the cylinder bore 13. The swinging motion generated by the rotation of the swash plate 9 is the plunger 11. It is converted into reciprocating motion.

  In the pump having this structure, a pump chamber 14 is formed in the cylinder 12 by a plurality of cylinder bores 13 and plungers 11. A suction space 15 communicating with each plunger 11 is provided at the center of the cylinder 12 so as to supply fuel to the pump chamber 14. In order to guide the fuel to the suction space 15, a fuel pipe outside the pump is attached to the rear body 20, passes through a suction passage in the rear body 20, and a suction space 15 provided in the cylinder 12 with a suction chamber 30 in the center of the rear body 20. Are connected to each other.

  A suction valve 24 (check valve) for sucking fuel, a ball 21, a spring 22, and a stopper 23 that supports the spring 22 are provided in the plunger 11. A plunger spring 25 is inserted for the purpose of constantly pressing the plunger 11 toward the swash plate 9 and causing the plunger 11 to follow the swash plate 9 together with the slipper 10.

  A communication path A <b> 16 to the suction valve 24 in the plunger 11 is formed as a communication path between the counterbore 51 provided in the cylinder bore and the suction space 15. The counterbore 51 is larger in diameter than the cylinder bore 13, and when the pump chamber 14 is sufficiently small (when the plunger position is at the top dead center) so that fuel can always be introduced into the plunger 11, the introduction hole 19 and the counterbore It is formed to such a depth that it can communicate with 51.

  In the swash plate type axial plunger fuel pump of FIG. 13, the rear body 20 uses an aluminum material as a component in contact with the fuel. Corrosion resistance is required when the rear body 20 is corrosive with a fuel gasoline obtained by adding methyl alcohol or ethyl alcohol, various gasoline additives, or deteriorated gasoline. Other components, for example, the cylinder 12 is stainless steel, and the cylinder bore 13 is alloy tool steel.

  The rear body 20 includes fuel flow paths such as a discharge valve 28, a discharge chamber 29, and a suction chamber 30. Further, the rear body 20 is fastened to the body 5, and its airtightness is secured by an O-ring 31.

  Therefore, in this embodiment, the plating film having the structure shown in FIG. 1 is formed on the entire rear body 20 of the fuel pump. The P concentration of the Ni—P plating film was about 11 wt.%, The thickness was 15 μm, and the thickness distribution was ± 2 μm. The rear body 20 was heat-treated at 250 ° C. for 1 hour in the atmosphere. As a result, the hardness of the Ni-P plating film was as high as Hv657 from about Hv520 as it was.

  Next, an actual machine durability test of the fuel pump of this example was performed. The fuel was gasoline with 15% ethanol added and tested at a rotational speed of 3500 r / min and a discharge pressure of 12 MPa. As a result, the pump operated without any abnormality, and a stable value for gasoline discharge flow rate was obtained. After the test, the parts were disassembled and the results of inspection of each part in the fuel chamber were confirmed. The occurrence of corrosion in any of the above parts, as well as the occurrence of wear in the fuel flow path due to corrosion, cavitation, and erosion, was not observed. Met. On the other hand, in the non-treated case, in the O-ring seal part of the rear body, the entire circumference that was in contact with the O-ring and the fuel flow path in the discharge chamber were worn due to corrosion by aluminum and ethanol.

  As described above, since the Ni-P or Ni-P plating film is formed in the fuel flow path of the fuel pump in this embodiment, the occurrence of corrosion, cavitation, and further wear due to erosion are suppressed, and their environmental resistance is improved. I was able to. In addition, this makes it possible for the first time to use a fuel pump using aluminum or an aluminum alloy, and a complex-shaped fuel pump can be easily realized.

Sectional drawing of the pump main body of the fuel pump in one Example of this invention. 1 is a partial cross-sectional view of a pump body of a fuel pump according to an embodiment of the present invention. Explanatory drawing of the structure of the surface treatment layer in one Example of this invention. Explanatory drawing of the other structure of the surface treatment layer in one Example of this invention. Explanatory drawing of the other structure of the surface treatment layer in one Example of this invention. Explanatory drawing of the structure of the other surface treatment layer in one Example of this invention. 1 is a partial cross-sectional view of a fuel pump according to an embodiment of the present invention. The figure explaining the corrosion resistance of the aluminum material which plated various materials and Ni-P. The figure which shows the volume reduction amount by the cavitation wear of various materials. The figure explaining the influence of the heat processing in cavitation wear. The figure explaining the influence of the heat processing in cavitation wear. The partial cross section figure which shows the other Example of the fuel pump which concerns on one Example of this invention. Sectional drawing which shows the other Example of the fuel pump which concerns on one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shaft, 2 ... Coupling, 3 ... Pin, 4 ... Communication path C, 5 ... Body, 6 ... Engine cam, 7 ... Radial bearing, 8 ... Thrust bearing, 9 ... Swash plate, 10,245 ... Slipper,
DESCRIPTION OF SYMBOLS 11,102,231 ... Plunger, 12,108,250 ... Cylinder, 13 ... Cylinder bore, 14 ... Pump chamber, 15 ... Suction space, 16 ... Communication path A, 17 ... Seal, 18 ... Space, 19 ... Introduction hole, 20 ... rear body, 21, 26 ... ball, 22, 27, 256 ... spring, 23 ... stopper, 24 ... suction valve, 25 ... plunger spring, 28 ... discharge valve, 29 ... discharge chamber, 30 ... suction chamber, 31 ... O-ring 33 ... Coupling fitting part, 34 ... Oil path, 35 ... Shaft seal, 36 ... Oil return path, 100 ... Pump body, 103 ... Lifter, 105 ... Suction valve, 105a ... Suction hole, 105b ... Suction valve holder, DESCRIPTION OF SYMBOLS 106 ... Discharge valve, 106a ... Discharge stream, 106b ... Discharge valve holder, 110 ... Fuel intake passage, 111 ... Fuel discharge passage, 112 ... Pressurization chamber, 12 ... protector, 200 ... drive cam, 300 ... solenoid.

Claims (20)

  A pump body formed of aluminum or an aluminum alloy, and a cylinder in which a Ni-P or Ni-P-based plating film is formed in a fuel passage through which gasoline or alcohol-added gasoline of the pump body flows Fuel pump for internal direct fuel injection device.   2. The fuel pump for direct in-cylinder fuel injection device according to claim 1, wherein the Ni-P or Ni-P-based plating film has a thickness of 10 [mu] m or more.   2. The fuel pump for a direct in-cylinder fuel injection device according to claim 1, wherein the Ni—P or Ni—P plating film has a thickness of 10 μm to 50 μm.   2. The fuel pump for a direct in-cylinder fuel injection device according to claim 1, wherein the Ni—P or Ni—P plating film has a Hv of 500 or more.   2. An in-cylinder direct fuel injection fuel according to claim 1, wherein an oxide film or a chromate film is formed between said aluminum or aluminum alloy and said Ni-P or Ni-P plating film. pump.   The fuel pump for an in-cylinder direct fuel injection device according to claim 1, wherein an oxide film or a chromate film is further formed on the aluminum or aluminum alloy and the Ni-P or Ni-P plating film. The fuel flow path includes a pressurizing chamber and a low pressure chamber,
The pressurizing chamber and the low pressure chamber are separated by the aluminum or aluminum alloy,
2. The direct fuel injection fuel for a cylinder according to claim 1, further comprising a portion where aluminum or an aluminum alloy is exposed at a part of the low pressure chamber side of aluminum or aluminum alloy separating the pressurizing chamber and the low pressure chamber. pump.   The fuel pump for a direct in-cylinder fuel injection device according to claim 1, wherein the Ni-P or Ni-P-based coating is amorphous.   An in-cylinder having a pump body formed of aluminum or an aluminum alloy, a seal portion of a Ni-P or Ni-P plating film applied to the aluminum or aluminum alloy, and a pressure contact member Fuel pump for direct fuel injection device.   The fuel pump for a direct in-cylinder fuel injection device according to claim 9, wherein the seal portion of the Ni-P or Ni-P plating film has a thickness of 10 µm or more.   The in-cylinder direct fuel injection device fuel pump according to claim 9, wherein the seal portion of the Ni-P or Ni-P plating film has a thickness of 10 µm or more and 50 µm or less.   The in-cylinder direct fuel injection device fuel pump according to claim 9, wherein the seal portion of the Ni-P or Ni-P plating film is Hv500 or more.   The oxide film or chromate film is formed between the pump part formed of the aluminum or aluminum alloy and the seal part of the Ni-P or Ni-P plating film. In-cylinder direct fuel injection device fuel pump.   10. The cylinder according to claim 9, wherein an oxide film or a chromate film is further formed on the pump part formed of the aluminum or aluminum alloy and the seal part of the Ni-P or Ni-P plating film. Fuel pump for internal direct fuel injection device. The in-cylinder direct fuel injection device fuel pump according to claim 14, wherein the Ni-P or Ni-P-based coating is amorphous.   A fuel pump for an in-cylinder direct fuel injection device having a pump body formed of aluminum or an aluminum alloy, and each hole of a fuel flow path through which gasoline or alcohol-added gasoline of the pump body flows is shorter than other holes. A fuel pump for an in-cylinder direct fuel injection device, wherein the fuel pump is connected in the vicinity of the portion.   The fuel pump for an in-cylinder direct fuel injection device according to claim 16, wherein a Ni-P or Ni-P plating film is formed in the fuel flow path.   The in-cylinder direct fuel injection device fuel pump according to claim 16, wherein the plating film is 10 μm or more.   The in-cylinder direct fuel injection device fuel pump according to claim 16, wherein the plating film has a thickness of 10 μm to 50 μm. The in-cylinder direct fuel injection device fuel pump according to claim 16, wherein the Ni-P or Ni-P-based coating is amorphous.

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