Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1998-03-20
2002-06-25
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S456000, C285S374000
Reexamination Certificate
active
06408826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a common rail such as a high pressure fuel manifold in an accumulator fuel injection system of a diesel engine or a block rail.
2. Description of the Prior Arts
Conventionally, as thick kind of common rail, for example, as shown in
FIG. 11
, there has been known a common rail of the type which is structured such that a branch hole
21
-
2
portion communicating with an inner communication passage
21
-
1
disposed in a peripheral wall portion of a main pipe rail
21
end constituted by a circular pipe is made a pressure receiving seat surface
21
-
3
open to an outer direction, and pressing seat surface
22
-
3
constituted by a connection head portion
22
-
2
of a branch pipe
22
having a tapering conical shape and enlarged a diameter thereof by buckling is brought into contact and engaged with an end portion by using a joint metal fitting
23
surrounding an outer peripheral portion of the main pipe rail
21
adjacent to the pressure receiving seat surface, thereby fastening and connecting to a screw wall
23
-
1
portion projecting to the joint metal fitting
23
together with pressing under the connection head portion
22
-
2
neck by means of an engagement of a fastening nut
24
previously assembled in the branch pipe end. In the drawing, reference numeral
22
-
1
denotes a flow passage of the branch pipe
22
and reference numeral
25
denotes a sleeve washer.
However, in the case of the common rail of the type that the joint metal fitting type common rail which is structured such that the joint metal fitting
23
is outwardly fitted to the main pipe rail
21
and the nut
24
meshed with the joint metal fitting
23
is fastened and connected, as shown in
FIG. 11
, a great stress is generated in an inner peripheral edge portion P of a lower end of the branch hole
12
-
2
due to an axial force applied to the pressure receiving seat surface
21
-
3
together with the internal pressure of the main pipe rail
21
and the pressing of the connection head portion
22
-
2
in the branch pipe
22
, so that a crack is easily generated with starting from the lower end inner peripheral edge portion P and there is a possibility of inviting a leakage.
SUMMARY OF THE INVENTION
The present invention is made so as to solve the conventional problems mentioned above, and an object of the invention is to provide a common rail which can reduce a maximum tensile stress value generated in an inner peripheral edge portion of a lower end of a branch hole and can improve an internal pressure fatigue strength and a method of manufacturing the same.
In order to achieve the object mentioned above, in accordance with a first aspect of the invention, there is provided 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, in which a compression residual stress is present at a portion near the open end portion of the communication passage of the main pipe rail in the branch hole.
Further, in accordance with a second aspect 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, in which a pressing force is applied to the main pipe rail near the branch hole from an outer portion to a diametrical direction, preferably 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. Further, in this case, the branch hole is punched at the same time as the pressing force is applied to the main pipe rail near the branch hole form the outer portion to the diametrical direction by an external pressing method.
Still further, in accordance with a third aspect 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, in which a pressing force is applied to an inner peripheral surface of the main pipe rail near the branch hole by an internal pressing 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.
Furthermore, in accordance with a fourth aspect 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, in which a pressing force is applied to an inner peripheral surface of the main pipe rail near the branch hole by a pipe expansion method which applies a pressure to a pipe diametrical direction from an inner portion of the main pipe rail, 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.
Moreover, in accordance with a fifth aspect 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 po
Asada Kikuo
Kusanagi Ryuichi
Takikawa Kazunori
Usui Masayoshi
Watanabe Eiji
Casella Anthony J.
Hespos Gerald E.
Miller Carl S.
Usui Kokusai Sangyo Kaisha Limited
LandOfFree
Common rail and method of manufacturing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Common rail and method of manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Common rail and method of manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2953496