Usui Kokusai Sangyo Kaisha Limited

Ryuichi Kusanagi

Kikuo Asada

Masayoshi Usui

Kazunori Takikawa

Eiji Watanabe

Kaneyuki Imai

A short common rail requiring less expensive manufacturing cost is provided. The common rail includes a short body portion formed of a thick tube body, a cap bonded to openings on both ends of the body portion, a securing flange bonded to one end of the body portion, a branch connector formed of a branch pipe or a branch joint fitting inserted into a through hole formed on the body portion and bonded thereto. The respective components are assembled and bonded by means of brazing or diffusion bonding.

Common rail

This invention provides an improved method of projection welding which enables the sound welding of high-carbon, and high-tension low-alloy steels. A spacer is disposed between two parts to be joined by projection welding. At least one of the parts is made of a high-carbon, or high-tension low-alloy steel. The spacer is a thin sheet, or coating formed on at least one of those parts.

Method for the projection welding of high-carbon steels and high-tension low-alloy steels

A connection head at a connection end of a thick wall steel pipe has an outer end face formed as a truncated cone or a truncated sphere. A lower neck portion is formed at the rear of the connection head and has a cylindrical outer surface and a taper to the outer surface of the pipe. A connection washer covers the lower neck portion of the connection head. A shallow gently sloping annular groove is produced inside the connection head as a result of a press forming. The above structure can prevent fatigue fracture due to stress concentration at the annular groove inside the head and sticking of a nut to the washer due to excessive tightening torque.

High-pressure metal pipe with connection head, method of forming the head and connection washer for the connection head

There is provided a common rail which can effectively restrict a generation of a stress in a lower end inner peripheral edge portion of a branch hole and can improve an internal pressure fatigue strength in a branch pipe connecting portion, so that a secure and stable function can be obtained by having an excellent durability and preventing a fluid leakage due to a generation of the crack generation and a method of manufacturing a common rail in which a pressure application process by the press is only added to a normal manufacturing process, no complex equipment is required, a common rail having a high quality can be manufactured by a low cost without generating problems that an equipment cost is increased by an increase of the process and a productivity is reduced. In the method of the invention, there is provided a method of manufacturing a common rail comprising at least one branch hole provided in an axial peripheral wall portion of a main pipe rail having a communication passage inside an axial core, a pressure receiving seat surface communicating with a branch pipe having a communication passage communicating with the communication passage in a peripheral surface portion of the branch hole and open to an outer portion, thereby bringing a pressing seat surface portion constituted by a connection head portion disposed in an end portion of the branch pipe into contact and engaging therewith, and a joint metal fitting surrounding an outer peripheral portion of the main pipe rail and a nut previously assembled in the branch pipe end which are meshed with each other so as to be pressed under a neck portion of the connection head portion, thereby being fastened and connected, wherein a pressing force is applied to the main pipe rail near the branch hole from an outer portion to a diametrical direction by a press method, thereby generating a compression residual stress at a portion near the open end portion of the communication passage of the main pipe rail in the branch hole.

Common rail and method of manufacturing the same

METHOD FOR IMPROVING FATIGUE STRENGTH DUE TO REPEATED PRESSURE AT BRANCH HOLE PART IN MEMBER FOR HIGH PRESSURE FLUID, BRANCH HOLE PART OF MEMBER FOR HIGH PRESSURE FLUID FORMED BY THE METHOD, AND MEMBER FOR HIGH PRESSURE FLUID WITH BUILT-IN SLIDER HAVING THE BRANCH HOLE

A method is provided for manufacturing common rails, such as a high-pressure fluid manifold or a block rail that may be use in an accumulator fluid injection system. The method includes providing a main tubular rail with a flow passage extending in an axial direction. A bottomed lower hole is formed generally transverse to the axial flow passage. A pressing force is applied to the bottomed lower hole to generate a residual compressive stress in a circumferential part of the end portion of the bottom hole. The bottom lower hole then is made to communicate with the flow passage in the main rail. Defects that may have been caused by the application of the pressing force then are cut off. The removal of the defects improves an internal pressure fatigue strength, achieves high durability and ensures freedom from leakage.

Method of manufacturing common rails

There is provided a common rail which can effectively restrict a generation of a tensile stress in a lower end inner peripheral edge portion of a branch hole by canceling by means of a compression residual stress and can improve an internal pressure fatigue strength in a branch pipe connecting portion, so that a secure and stable function can be obtained by having an excellent durability and preventing a fluid leakage due to a generation of the crack generation and a method of manufacturing a common rail in which a pressure application process is only added to a normal manufacturing process, no complex equipment is required, and a common rail having a high quality can be manufactured by a low cost without generating problems that an equipment cost is increased by an increase of the process and a productivity is reduced. In a method of manufacturing a common rail structured such that a branch hole communicating with an communication passage of a block rail and having a pressure receiving seat surface open to an outer portion is provided in at least one connecting hole portion provided in a peripheral wall portion in an axial direction of the block rail having the communication passage in a longitudinal inner portion, a pressing seat surface constituted by a connecting head portion provided in an end portion of a branch having a flow passage communicating with the communication passage is brought into contact with and engaged with the pressure receiving seat surface, and the connecting hole portion and a fastening nut previously assembled in the branch pipe are meshed with each other so as to fasten and connect together with pressing under a neck of the connecting head portion, a pressing force is applied to an axial direction of the connecting hole portion from an outer portion by a press method so as to generate a compression residual stress in the periphery of an open end portion of the communication passage of the block rail of the branch hole.

A common rail includes a generally cylindrical peripheral wall having a communication passage extending axially therethrough. At least one branch hole extends through the peripheral wall and is aligned perpendicular to the axis of the common rail. The intersection of the branch hole with the outer surface of the main pipe rail defines an outwardly flared pressure receiving seat for receiving the connection head portion of a branch pipe. A sleeve nipple is welded or brazed to the outer surface of the main pipe rail and surrounds the branch hole. Inner surface regions of the peripheral wall surrounding the branch hole have a compression residual stress imparted thereto. The creation of the compression residual stress may cause a portion of the inner surface of the main pipe rail surrounding the branch hole to assume a non-cylindrical configuration.

Growing community of inventors

Numazu, Japan

Ryuichi Kusanagi