Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
2000-02-24
2001-09-11
Morris, Lesley D. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C029S890143
Reexamination Certificate
active
06286769
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a concentric connecting method for precise parts comprising a plurality of members, a method for assembling a nozzle of a fuel injection valve making use of the former, and a fuel injection valve.
BACKGROUND ART
For a concentric connecting method for precise parts comprising a plurality of members, an example of a conventional nozzle assembly will be described with reference to Japanese Patent Publication No. Hei. 7-10471 (corresponding to U.S. Pat. No. 5,127,156, GB 2,236,359, DE 4,030,320). In
FIG. 1
of the aforesaid Publication, a tapered hole (a valve seat)
10
c
is formed in the inner bottom provided with an orifice
11
of a nozzle body (an outer tubular part)
10
, a swirler (an inner tubular part)
12
with a through-hole
12
a
is installed within the nozzle body
10
while securing a clearance therebetween, the vicinity (on the swirler side) of a fitting portion between the swirler
12
and the nozzle body
10
is pressed by a punch
16
so as to generate a local plastic flow while centering the tapered hole
10
c
with respect to the through-hole
12
a
of the swirler
12
by a positioning guide pin
14
, and both the parts are connected concentrically by force of the plastic flow thus generated. The swirler
12
is internally formed with a fuel swirling force generating groove for applying swirl to fuel, and fuel is injected out of a fuel injection valve while swirling.
As mentioned in the above prior art, a swirler (an inner tubular part)
12
with a through-hole
12
a
is installed within the nozzle body
10
while securing a clearance G therebetween, the vicinity of a fitting portion of the swirler
12
is pressed by a punch
16
so as to generate a local plastic flow while centering the tapered hole
10
c
with respect to the through-hole
12
a
of the swirler
12
by a positioning guide pin
14
, and both the parts are connected concentrically by force of the plastic flow, in such a case, a residual stress due to the plastic flow occurs without fail in the connecting portion.
If a coaxial degree of the inside and outside diameters of the swirler
12
is 0, and a coaxial degree of the inside diameter of the nozzle body
10
and the tapered hole
10
c
is 0, the residual stress is generated uniformly over the whole circumference, by which ideal concentric connection is attained. However, where either of the parts has deflection, that is, the coaxial degree is not 0, or where the coaxial degree between the outside diameter and the inside diameter of the swirler
12
is not 0, the dimension of the clearance G in the whole circumference is partly varied, so that the residual stress of the whole circumference of the connecting portion becomes unbalanced. Because of this, when the positioning guide pin
14
is removed, the spring back amount in the whole circumference is different due to the unbalance of the residual stress, resulting in deviation of center. As described, in the conventional method, there remains considerably an influence of accuracy of an individual part of the parts on the coaxial degree after connection. In the case of the embodiment in the aforesaid Publication, the coaxial degree after connection is 5.8 &mgr;m on the average.
Further, where both the nozzle body
10
and the swirler
12
are formed of a combination of materials that are not subjected to plastic flow, such as a hardening material, it is impossible to connect both the parts making use of plastic flow. Therefore, the method as in the above-described prior art cannot be employed.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a concentric connecting method for precise parts comprising a plurality of members, a method for assembling a nozzle of a fuel injection valve making use of the former, and a fuel injection valve, which are free from influence of precision of an individual part of parts, and capable of keeping a coaxial degree after connection.
For achieving the aforementioned object, the present invention provides a method comprising: fitting a swirler and a plate so that the swirler is held between a seat portion of a nozzle and the plate in an inside diameter portion of a nozzle of a fuel injection valve, centering the seat portion of the nozzle with respect to an inside diameter portion of the swirler, causing the plastic flow locally on the plate, and connecting and fixing the nozzle, the swirler and the plate.
More specifically, where a swirler is concentrically fixed to a nozzle body, both are fitted in a state in which the swirler is placed on the internal bottom of the nozzle body and fitted with the nozzle body while securing a clearance between the inside diameter portion of the nozzle body and the outside diameter portion of the swirler; a plate having a through-hole slightly larger than a through-hole of the swirler for fixing the swirler so as to be held in a sandwich-like manner is fitted on the upper surface of the swirler; in such a fitting state, a positioning guide pin having substantially the same diameter as the inside diameter portion of the swirler and formed at a tip thereof with the centering surface relative to a tapered hole (a valve seat) of the nozzle body and the insert guide surface is inserted into the inside diameter portion of the swirler till the tip of the pin comes into contact with the tapered hole (valve seat) of the nozzle body to carry out temporary concentric positioning of the inside diameter portion of the swirler and a tapered hole of the nozzle body; and in the temporary positioning state, a punch is moved and guided in the same direction as the inserting direction of the positioning guide pin along the outer circumference of the positioning guide pin, the vicinity of a fitting portion between the plate and the nozzle body (mainly the plate side) is pressed by the punch so that a local plastic flow occurs, and the swirler is fixed to the nozzle body through force of plastic flow acting in the diametral direction and the axial direction generated in the plate to connect and fix the plate to the nozzle body.
Deviation in center occurs in the plate after connection because the unbalance of clearance in the whole circumference causes the spring back amount different, similarly to the case of the swirler in the prior art. However, an tapered hole of the nozzle (valve seat) and the swirler requiring high coaxial degree are merely fixed by being held between the plate and the nozzle, and the spring back due to the residual stress is not exerted, accordingly, they are connected and fixed intact at the position determined by a positioning guide pin, and the tapered hole of the nozzle (valve seat) and the swirler are maintained in high coaxial degree.
REFERENCES:
patent: 5127156 (1992-07-01), Yokoyama et al.
patent: 5871157 (1999-02-01), Fukutomi et al.
patent: 5979801 (1999-11-01), Munezane et al.
patent: 6065692 (2000-05-01), Brinn, Jr.
patent: 6145761 (2000-11-01), Muller et al.
patent: 6170762 (2001-01-01), Sumida et al.
patent: 4030320-A1 (1991-04-01), None
patent: 2236359-A (1991-04-01), None
Gunji Kenichi
Tanabe Yoshiyuki
Crowell & Moring LLP
Hitachi , Ltd.
Morris Lesley D.
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