JP2019011695A - Fuel delivery pipe, and plating method for applying plating only to inner peripheral part og sensor fitting plug of fuel delivery pipe - Google Patents

Abstract

To prevent a fuel pressure sensor from being adhered to a socket fitting plug, without reducing corrosion resistance of a fuel delivery pipe.SOLUTION: A fuel delivery pipe 10 comprises: multiple injection valve sockets 20 that are provided in a main pipe 11; and a cylindrical sensor fitting plug 15 provided in the main pipe 11 and fitting a fuel pressure sensor S that detects a fuel pressure within a fuel passage 11a, in its inner peripheral part. A corrosion resistant stainless material is used for at least a fitting part S1 of the fuel pressure sensor S and the sensor fitting plug 15, and the injection valve sockets 20 and the sensor fitting plug 15 are integrally fixed to the main pipe 11 by brazing. A plating part 15d is provided by applying electroless nickel-phosphor plating only to the inner peripheral part of the brazed sensor fitting plug 15. Vickers hardness of the plating part 15d ranges from 250 to 900 HV and a coefficient of static friction ranges from 0.10 to 0.20.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel delivery pipe used for supplying fuel to an engine and a plating method for plating only an inner peripheral portion of a sensor mounting plug of the fuel delivery pipe.

  Patent Document 1 discloses an invention of an outboard motor for a ship, and an engine unit of the outboard motor includes a fuel delivery pipe for supplying fuel to a combustion chamber of a cylinder head. Since the fuel delivery pipe used for the outboard motor is used in a corrosive environment by seawater, a stainless material having high corrosion resistance is often used. In general, a sensor delivery plug is provided in the fuel delivery pipe, and a fuel pressure sensor for detecting the fuel pressure in the fuel passage is attached to the sensor attachment plug. The fuel pressure sensor has a male screw part for mounting. The male screw part of the fuel pressure sensor is attached to the inner part of the inner part of the sensor mounting plug and sealed, and the male screw part of the fuel pressure sensor is attached to the sensor. It is fastened and attached to an internal thread formed on the inner periphery of the plug.

JP2015-227629A

  As described above, a stainless steel material having high corrosion resistance is often used for a fuel delivery pipe used in an outboard motor such as Patent Document 1, and a fuel pressure sensor attached by being fastened to a sensor attachment plug is attached. The stainless steel material having high corrosion resistance is often used for the screw portion for use. When the male screw part of the fuel pressure sensor is tightened and attached to the sensor mounting plug, the sensor mounting plug and the male screw part of the fuel pressure sensor are the same metal and have high mutual solubility. Adhesion may occur between the inner periphery of the sensor mounting plug and the inner part of the sensor mounting plug, which may make it impossible to remove the fuel pressure sensor from the sensor mounting plug. If a material other than stainless steel is used for the sensor mounting plug, the fuel pressure sensor can be prevented from sticking to the socket mounting plug, but the sensor mounting plug must be made of a material other than stainless steel in order to use the fuel delivery pipe in a corrosive environment. It was not possible to make the material. In addition, if electroless nickel-phosphorous plating is applied to the entire fuel delivery pipe, the fuel pressure sensor can be prevented from sticking to the socket mounting plug, but the corrosion resistance of the outer peripheral surface of the fuel delivery pipe is reduced. For this reason, it is not appropriate to apply an electroless nickel-phosphorus plating treatment to the entire fuel delivery pipe. An object of the present invention is to prevent a fuel pressure sensor from adhering to a socket mounting plug without lowering the corrosion resistance of the outer peripheral surface of the fuel delivery pipe.

  In order to solve the above problems, the present invention provides a main pipe in which a fuel passage to which fuel is supplied from a fuel pump is formed, and a plurality of injection valve sockets provided in the main pipe and connected to the fuel injection valve. And a cylindrical sensor mounting plug for mounting a fuel pressure sensor provided on the main pipe for detecting the fuel pressure in the fuel passage, and the injection valve socket and the sensor mounting plug are integrally fixed to the main pipe by brazing. A fuel delivery pipe that is made of corrosion-resistant stainless steel for at least the fuel pressure sensor mounting portion and the sensor mounting plug that are mounted on the inner periphery of the sensor mounting plug. A plating part with electroless nickel-phosphorous plating is provided only on the inner peripheral part of the steel plate, and the Vickers hardness of this plating part is 250 to 900H. , There is provided a fuel delivery pipe, characterized in that the static friction coefficient so as to be 0.10 to 0.20.

  In the fuel delivery pipe configured as described above, a corrosion-resistant stainless steel material is used for at least the fuel pressure sensor mounting portion and the sensor mounting plug attached to the inner peripheral portion of the sensor mounting plug. A plating part with electroless nickel-phosphorous plating is provided only on the inner peripheral part of the sensor mounting plug, and the plating part has a Vickers hardness of 250 to 900 HV and a static friction coefficient of 0.10 to 0.20. Therefore, while maintaining the outer peripheral surfaces of the main pipe and sensor mounting plug in a highly corrosion-resistant state of stainless steel, the inner periphery of the sensor mounting plug in which the mounting portion of the fuel pressure sensor is plated with electroless nickel-phosphorous plating It was possible to avoid sticking to the part.

  In order to solve the above problems, the present invention provides a main pipe in which a fuel passage to which fuel is supplied from a fuel pump is formed, and a plurality of injection valve sockets provided in the main pipe and connected to the fuel injection valve. And a sensor mounting plug in the form of a cylinder that is provided on the main pipe and detects a fuel pressure in the fuel passage and that is attached to the inner periphery of the sensor, and is attached to at least the inner periphery of the sensor mounting plug. The inner circumference of the sensor mounting plug of the fuel delivery pipe in which corrosion resistant stainless steel is used for the sensor and the sensor mounting plug, and the injection valve socket and the sensor mounting plug are integrally fixed to the main pipe by brazing This is a plating method in which plating is applied only to the outer periphery of the fuel delivery pipe other than the inner periphery of the sensor mounting plug. King treatment step, nickel strike plating treatment step in which the inner periphery of the sensor mounting plug including the covered part of the fuel delivery pipe after the masking treatment step is immersed in the plating solution and wood bathing, and the fuel after the nickel strike plating treatment An electroless nickel-phosphorous plating treatment step in which the inner peripheral portion of the sensor mounting plug including the covered portion of the delivery pipe is immersed in a plating solution and electroless nickel-phosphorous plating is applied to the inner peripheral portion of the sensor mounting plug; The present invention provides a plating method for plating only the inner peripheral portion of a sensor mounting plug of a fuel delivery pipe, comprising a masking removal processing step for removing a coating after an electroless nickel-phosphorous plating processing step. .

  By the plating method for plating only the inner periphery of the sensor mounting plug of the fuel delivery pipe configured as described above, while maintaining the outer peripheral surface of the main pipe and the sensor mounting plug in a highly corrosion-resistant state of stainless steel, It has become possible to obtain a fuel delivery pipe in which the attachment portion of the fuel pressure sensor is not adhered to the inner peripheral portion of the sensor attachment plug provided with a plating portion made of electroless nickel-phosphorous plating.

1 is a side view of a fuel delivery pipe according to the present invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is the side view which stood up the fuel delivery pipe which masked a part. It is AA sectional drawing corresponding to FIG. 2 which shows the masked part and the part which plated. It is a flowchart which shows the plating method of the fuel delivery pipe which plating only to the inner peripheral part of a sensor attachment plug.

  Hereinafter, an embodiment of a plating method for plating only a fuel delivery pipe according to the present invention and an inner peripheral portion of a sensor mounting plug of the fuel delivery pipe will be described with reference to the accompanying drawings.

  The fuel delivery pipe 10 of the present invention is mainly used for an engine of an outboard motor of a ship, and is assumed to be used in a corrosive environment such as at sea. As shown in FIGS. 1 to 3, the fuel delivery pipe 10 closes both ends of the main pipe 11 and a main pipe 11 in which a fuel passage 11 a to which fuel is supplied from a fuel pump (not shown) is formed. Covers 12 and 13, four (plural) injection valve sockets 20 provided on the main pipe 11 to which the fuel injection valve I is liquid-tightly connected, and a fuel supply pipe (not shown) provided on the main pipe 11. ) Are connected, and a cylindrical sensor attachment plug 15 provided on the main pipe 11 and attached to the inner periphery of a fuel pressure sensor S for detecting the fuel pressure in the fuel passage 11a. In the fuel delivery pipe 10, the main pipe 11, the lid bodies 12 and 13, the joint pipe 14, the sensor mounting plug 15, and the injection valve socket 20 are made of a stainless material having high corrosion resistance.

  As shown in FIG. 1, the main pipe 11 uses a stainless steel pipe material having a circular cross-sectional shape. Lids 12 and 13 are provided at both ends in the longitudinal direction of the main pipe 11, and the internal space of the main pipe 11 closed by the lids 12 and 13 serves as a fuel passage 11a. A joint pipe 14 is fixed to an intermediate portion in the longitudinal direction of the main pipe 11, and fuel supplied from a fuel pump (not shown) passes through the fuel supply pipe (not shown) and the joint pipe 14 in the main pipe 11. To the fuel passage 11a.

  A cylindrical sensor mounting plug 15 is provided on the right side of the main pipe 11 in the longitudinal direction shown in FIG. 1, and the fuel pressure of the fuel passage 11 a is supplied to the inner peripheral portion of the sensor mounting plug 15. A fuel pressure sensor S to be detected is detachably attached. The sensor mounting plug 15 is made of stainless steel and has a Vickers hardness of about 350 HV. As shown in FIG. 2, the inner peripheral portion of the sensor mounting plug 15 is connected to the main pipe 11 side from the opening side to the female screw portion 15a to which the male screw portion S1 of the fuel pressure sensor S is fastened, and from the female screw portion 15a to the main pipe 11 side. A truncated cone surface portion 15b having a small diameter and a pore 15c formed on the main pipe 11 side from the truncated cone surface portion 15b are provided. When the male screw portion S1 of the fuel pressure sensor S is fastened (screwed) to the female screw portion 15a of the sensor mounting plug 15, the tip of the male screw portion S1 of the fuel pressure sensor S is connected to the inner portion of the inner peripheral portion of the sensor mounting plug 15. Thus, the fuel in the fuel passage 11 a is prevented from leaking from the sensor mounting plug 15. The pore 15c formed in the sensor mounting plug 15 is disposed at a position facing the communication hole 11b formed in the main pipe 11, and the inside of the sensor mounting plug 15 communicates with the fuel passage 11a through the pore 15c and the communication hole 11b. doing.

  The fuel pressure sensor S attached to the sensor attachment plug 15 is made of a stainless steel material for the exterior part and the external thread part S1, and has a Vickers hardness of about 180 HV.

  As shown in FIG. 1, four injection valve sockets 20 are fixed to the side surface of the main pipe 11, and the four injection valve sockets 20 are arranged at equal intervals in the longitudinal direction of the main pipe 11. As shown in FIGS. 1 and 3, the injection valve socket 20 includes a cylindrical socket portion 21 whose upper portion is closed, an arm portion 22 that connects the socket portion 21 to the main pipe, and a side portion of the socket portion 21. A bracket portion 23 for fixing the fuel delivery pipe 10 to the engine is provided. The injection valve socket 20 is fixed to the position where the fuel supply hole 11c of the main pipe 11 is formed, and the inside 21a of the socket portion 21 is communicated with the fuel passage 11a by the passage 22a inside the fuel supply hole 11c and the arm portion 22. Yes. The socket 21 is connected to a fuel injection valve I that is opened and closed under the control of the control unit. A cylindrical bracket portion 23 is integrally provided on a side portion of the socket portion 21, and the fuel delivery pipe 10 is fixed to the engine by a bolt inserted into a bolt insertion hole 23 a of the bracket portion 23. The bracket portion 23 may be a separate body from the injection valve socket 20.

  Next, a method for manufacturing the fuel delivery pipe 10 will be described. The method for manufacturing the fuel delivery pipe 10 includes a step of fixing the lid bodies 12 and 13, the joint pipe 14, the sensor mounting plug 15 and the four injection valve sockets 20 to the main pipe 11 by brazing, and a sensor mounting plug after brazing. And a plating process for only 15 inner peripheral portions.

  In the process of fixing by brazing, the lid bodies 12 and 13, the joint pipe 14, the sensor mounting plug 15 and the four injection valve sockets 20 are temporarily fixed to the main pipe 11, and the fuel delivery pipe 10 in the temporarily fixed state is brazed. To fix them together.

  Next, the process of plating only the inner peripheral portion of the sensor mounting plug 15 will be described. The process of plating only the inner peripheral portion of the sensor mounting plug 15 is a fuel pressure made of the same metal on the inner peripheral portion of the sensor mounting plug 15 while maintaining the corrosion resistance of the outer peripheral surface of the fuel delivery pipe 10 made of stainless steel. This is intended to prevent the male screw portion (mounting portion) S1 including the sealing surface of the tip portion of the sensor S from sticking.

  As shown in FIG. 6, the plating method for plating only the inner peripheral portion of the sensor mounting plug 15 of the fuel delivery pipe 10 is at least a masking process, a nickel strike plating process, and an electroless nickel-phosphorous plating. It includes a processing step and a masking removal step. If the Vickers hardness of the plating portion 15d formed on the inner peripheral portion of the sensor attachment plug 15 is lower than 250 HV, a baking processing step is performed as necessary. is there. In this embodiment, after the masking process, a drying process and a degreasing process are performed, after the nickel strike plating process, a water washing process is performed, after the electroless nickel-phosphorous plating process, a water washing process, and a drying process, A masking removal process and a degreasing process are performed, and finally a baking process is performed as necessary.

  In the nickel strike plating process and the electroless nickel-phosphorus plating process, the main pipe 11 is moved vertically so that the sensor mounting plug 15 is below the middle part of the main pipe 11 in the longitudinal direction as shown in FIG. Since the fuel delivery pipe 10 is suspended in the standing state and the fuel delivery pipe 10 is immersed in the plating solution in the plating bath B, the masking material is applied to a position slightly above the sensor mounting plug 15 of the fuel delivery pipe 10 in the masking process. (The portion where the masking material is applied is shown by a two-dot chain line in FIG. 5). In order to plate the female thread portion 15a and the truncated cone surface portion 15b particularly at the inner peripheral portion of the sensor mounting plug 15, in the masking process step, the outer peripheral portion of the sensor mounting plug 15 is coated and coated with a fuel. In order to prevent the plating solution from flowing into the passage 11a, the cap C1 is inserted into the pore 15c of the sensor mounting plug 15 as shown in FIG. In addition, in the two injection valve sockets 20 that are on the lower side when they stand, the opening 21b of the socket part 21 is closed with the cap C2, and the opening parts on both sides of the bolt insertion hole 23a of the bracket part 23 are closed with the cap C3. Block it. In the masking process, the masking material is applied and coated, but the masking material is not limited to this, and the masking material may be sprayed or sprayed with masking tape. Also good.

  After the fuel delivery pipe 10 is masked, the oil delivery component attached to the fuel delivery pipe is removed from the fuel delivery pipe 10 by a drying process and a degreasing process, and the fuel delivery pipe 10 is subjected to nickel strike plating. In the nickel strike plating process, an electric current is applied in a state where the masked portion of the fuel delivery pipe 10 is immersed in the plating solution in the plating bath B (wood bath), and the inner periphery of the sensor mounting plug 15 is applied. Then, the passivation film on the surface of the stainless steel material is removed and nickel strike plating is applied to the surface to enhance the adhesion of the electroless nickel-phosphorous plating described later.

  After the nickel strike plating treatment, the plating solution is washed away by a water washing step and electroless nickel-phosphorus plating treatment is performed. In the electroless nickel-phosphorous plating treatment step, the masked portion of the fuel delivery pipe 10 is immersed in a plating solution in the plating bath B (sulphur free to have a phosphorus concentration of 9 to 13%), which is shown by the one-dot chain line in FIG. As described above, the electroless nickel-phosphorous plating is applied to the portion of the stainless steel surface on which the nickel strike plating is applied at the inner peripheral portion of the sensor mounting plug 15 to form the plating portion 15d.

  After the electroless nickel-phosphorous plating treatment, the fuel delivery pipe 10 is washed and dried in the water washing process and the drying process, and the masking material coated on the fuel delivery pipe 10 is peeled off by the masking removal process, and the degreasing process. To remove the remaining oil and fat components. If the Vickers hardness of the plating part 15d is lower than 250 HV, the fuel delivery pipe 10 is baked after the degreasing process. In the baking process, the fuel delivery pipe 10 is heated in a heating chamber at 100 to 400 ° C. for 1 to 2 hours. Thus, the Vickers hardness of the plating part 15d formed on the inner peripheral part of the sensor mounting plug 15 subjected to the electroless nickel-phosphorous plating process (baked as necessary) is 400 to 500 HV, and the static friction coefficient is 0.10. It is 0.20. By performing electroless nickel-phosphorous plating (baking if necessary), the Vickers hardness of the plated portion 15d formed on the inner peripheral portion of the sensor mounting plug 15 is 400 to 500 HV, and the friction coefficient is 0.10. Even when the stainless steel male screw part (attachment part) S1 of the fuel pressure sensor S is fastened and attached to the inner peripheral part of the sensor attachment plug 15, the tip part of the male screw part S1 of the fuel pressure sensor S is It was possible to prevent the sensor mounting plug 15 from sticking to the frustoconical surface portion 15b of the inner peripheral portion. Thereby, even when the fuel pressure sensor S fails, the fuel pressure sensor S can be removed and replaced. Further, a plating portion 15 d for preventing the tip of the male screw portion S 1 of the fuel pressure sensor S from adhering to the truncated cone surface portion 15 b of the inner peripheral portion of the sensor mounting plug 15 is provided only on the inner peripheral portion of the sensor mounting plug 15. Since it was formed, the outer peripheral surface of the fuel delivery pipe 10 was able to keep the corrosion resistance of the stainless steel material from being lost. In this embodiment, the electroless nickel-phosphorous plating process is performed on the inner peripheral part of the sensor mounting plug 15 (the baking process is performed if necessary), thereby forming a plating part formed on the inner peripheral part of the sensor mounting plug 15. The Vickers hardness of 15d is set to 400 to 500 HV, but the present invention is not limited to this, and if the Vickers hardness of the plating part 15d is in the range of 250 to 900 HV, It is possible to prevent the seal surface at the tip from adhering to the inner portion of the sensor mounting plug 15.

  DESCRIPTION OF SYMBOLS 10 ... Fuel delivery pipe, 11 ... Main pipe, 11a ... Fuel path, 15 ... Sensor attachment plug, 15d ... Plate part, 20 ... Injection valve socket, S ... Fuel pressure sensor, S1 ... Attachment part (male thread part).

Claims (2)

A main pipe in which a fuel passage to which fuel is supplied from a fuel pump is formed;
A plurality of injection valve sockets provided in the main pipe to which fuel injection valves are connected;
A cylindrical sensor mounting plug provided on the inner periphery of a fuel pressure sensor provided on the main pipe for detecting a fuel pressure in the fuel passage;
A fuel delivery pipe in which the injection valve socket and the sensor mounting plug are integrally fixed to the main pipe by brazing,
At least the fuel pressure sensor mounting portion and the sensor mounting plug that are attached to the inner peripheral portion of the sensor mounting plug are made of a corrosion-resistant stainless steel,
After brazing, a plating part with electroless nickel-phosphorous plating is provided only on the inner periphery of the sensor mounting plug. The plating part has a Vickers hardness of 250 to 900 HV and a static friction coefficient of 0.10 to 0.20. A fuel delivery pipe characterized in that A main pipe in which a fuel passage to which fuel is supplied from a fuel pump is formed;
A plurality of injection valve sockets provided in the main pipe to which fuel injection valves are connected;
A cylindrical sensor mounting plug provided on the inner periphery of a fuel pressure sensor provided on the main pipe for detecting a fuel pressure in the fuel passage;
Corrosion-resistant stainless steel is used for at least the fuel pressure sensor mounting portion and the sensor mounting plug attached to the inner peripheral portion of the sensor mounting plug, and the injection pipe socket and the sensor mounting plug are connected to the main pipe. A plating method that applies plating only to the inner peripheral portion of the sensor mounting plug of the fuel delivery pipe that is integrally fixed by brazing,
A masking process for covering at least a part of the outer peripheral surface of the fuel delivery pipe other than the inner peripheral portion of the sensor mounting plug;
A nickel strike plating treatment step in which the inner peripheral portion of the sensor mounting plug including the covered portion of the fuel delivery pipe after the masking treatment step is immersed in a plating solution to make a wood bath;
After the nickel strike plating treatment, the inner peripheral portion of the sensor mounting plug including the portion covered with the fuel delivery pipe is immersed in a plating solution to apply electroless nickel-phosphorous plating to the inner peripheral portion of the sensor mounting plug. An electroless nickel-phosphorous plating process;
A plating method for plating only an inner peripheral portion of a mounting plug of a fuel delivery pipe sensor, comprising a masking removal processing step of removing a coating after the electroless nickel-phosphorous plating processing step.

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