Fluid handling – Removable valve head and seat unit – Retained by bonnet or closure
Reexamination Certificate
2000-06-14
2001-09-18
Shaver, Kevin (Department: 3754)
Fluid handling
Removable valve head and seat unit
Retained by bonnet or closure
Reexamination Certificate
active
06289922
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow control valve which controls a flow rate of fluid and which is preferably suitable for an idling engine speed control valve (ISCV) for controlling an air flow which bypasses a throttle valve during an idling of an engine.
2. Description of Related Art
One type of known flow control valve may cause a valve leakage at a gap between a valve element and a valve seat when the valve element is seated on the valve seat (when the valve is totally closed) because of dispersion regarding dimensional accuracy and assembly accuracy of each element and the like.
Another type of flow control valve may solve the above problem and may reduce the leakage. As shown in
FIG. 1
, such the flow control valve has a housing
100
, an air passage
110
formed in the housing
100
, a valve element
120
which opens and closes the air passage
110
, and an electromagnetic actuator
130
and the like. A rubber seat valve
140
is attached to a valve seat on which the valve element
120
is seated. The valve element
120
is lifted from the seat valve
140
by an attractive force of the actuator
130
and opens the air passage
110
when current is supplied to a coil
150
installed in the actuator
130
. The valve element
120
is pushed to the seat valve
140
by a spring force of a spring
160
and closes the air passage
110
when current is not supplied to a coil
150
.
According to this type of flow control valve, the gap between the valve element
120
and the seat valve
140
may be avoided even if dispersion regarding dimensional accuracy and assembly accuracy of each element occurs, because the seat valve
140
is pushed by the valve element
120
and deforms elastically. Therefore, the leakage may be reduced.
However, if this type of flow control valve is applied to an idling engine speed control valve, the rubber seat valve
140
absorbs gasoline, oil and the like and swells as shown in
FIG. 2
because such gasoline, oil or the like may be included in an air flow in the air passage
110
. In this case, the position of the valve element
120
shifts to the actuator
130
(to the right in
FIG. 1
) when the air passage
110
is totally closed. Therefore, the spring force of the spring
160
in a valve closing direction increases, and a required amount of current for the coil
150
to lift the valve element
120
from the full-close position increases. Thus, a predetermined flow rate characteristic (solid line in
FIG. 10
) changes to the one as shown by the dotted line in FIG.
10
.
Another known electromagnetic valve has a valve element which has a spherical seal surface (a surface to be contacted with a valve seat) to prevent a valve leakage caused by a valve element inclination. (See JP-U-4-27277.) According to this electromagnetic valve, a moving core for holding the valve element slides, keeping a contact with a guide portion. Therefore, a gap is formed between the guide portion and the moving core such that the moving core may slide with the contact. If the gap causes a displacement of the moving core in a radial direction for some reason, the center of the spherical seal surface is displaced from a shaft center which is the center of an opening of the valve seat. In this case, the seal surface of the valve element eccentrically contacts with the valve seat, and the valve closes imperfectly.
Furthermore, friction surfaces of the moving core or the guide portion may wear if the valve element is repeatedly seated on or detached from the valve seat. Such wear may cause an expansion of the gap between the guide portion and the moving core, and thereby the moving core is displaced in the radial direction and the center of the spherical seal surface is displaced from the shaft center which is the center of the opening of the valve seat. Therefore, the valve element may not be seated on the valve seat securely (without any gap), whereby valve leakage may result.
Another known flow control valve has been shown in
FIG. 3B. A
flow control valve
200
is mounted by being embedded in a recess
210
formed in a throttle body
290
. The flow control valve
200
has a mounting flange
211
. A packing
230
is located between the mounting flange
211
and a mounting surface
220
of the throttle body
290
. As shown in
FIG. 3A
, the flow control valve
200
is screwed and fixed to the throttle body
290
by three screws
222
at the mounting flange
211
.
It is desirable to reduce the mounting area of the flow control valve
200
for reducing the size of an engine to reduce the fuel consumption. As shown in
FIG. 4
, the inventors herein tried a method to screw and fix the flow control valve
200
to the throttle body
290
by one screw
222
at the mounting surface
211
, by locating seal members (O-rings)
240
at outer periphery of a housing of the flow control valve
200
and removing the packing
230
.
According to such method, tightening force K (
FIG. 4
) of the screw
222
is applied only at the periphery of the screw
222
, and the tightening force K is not applied to the mounting flange
211
at the opposite to the screw
222
. Accordingly, as shown in
FIG. 5
, the mounting flange
211
slid on the mounting surface
220
according to an oscillation in a direction of X, and an oscillation resonance Z, whose oscillation center is at the screw
222
, was generated. Measurement data measured at point C in
FIG. 5
showing the existence of the oscillation resonance are shown by chain line B in FIG.
16
.
SUMMARY OF THE INVENTION
The present invention is made in light of the foregoing problems, and it is an object of the present invention to provide a flow control valve whose flow rate characteristic is not changed by gasoline, oil or the like, and which reduces the valve leakage when the valve is closed even after repeated operations.
It is another object of the present invention to provide a flow control valve which reduces its mounting area at an engine, and which prevents the oscillation resonance caused by the engine vibration.
According to the flow control valve of the present invention, a seating surface formed on a valve element to contact a valve seat when the valve is closed has a shape of a part of a hypothetical spherical surface having a spherical center of a supporting center located at a center of a supporting member. Therefore, the distance from the supporting center to the seating surface is kept constant, and the valve element can be seated at a periphery of the valve seat without a gap, even if the shaft is inclined. Thus, the valve leakage is reduced.
The supporting member supports a shaft connected to the valve element movable in an axial direction of the shaft. The supporting center is aligned with a center of the valve seat. Movement of the supporting member in a radial direction of the supporting member is prohibited. Therefore, the supporting center is not displaced from the center of the valve seat in the radial direction. Accordingly, the displacement of the shaft in the radial direction can be prevented. Therefore, the valve element is certainly seated on the valve seat, and valve leakage is prevented.
According to another aspect of the present invention, a mounting flange having a mounting hole, which is for connecting the flange and a supporting surface by a fastener, is formed on an outer periphery of a housing. At least three protrusions are formed on the flange for dispersing a fastening force of the fastener to the protrusions. Therefore, the fastening force of the fastener is applied to the supporting surface by dispersing the fastening force on the protrusions.
Therefore, the fastening force of the fastener does not concentrate in one point with using only one fastener. Accordingly, the mounting flange has only one mounting hole to securely fix the flow control valve to the supporting surface, and the area of the mounting flange is reduced compared to the related art which uses a plurality of fasteners.
REFERENCES:
patent: 3197556 (1965-07-01), Simon
patent: 351924
Hasegawa Shigeru
Nakano Yuji
Takeyama Hiroshi
Yamada Yasuyoshi
Denso Corporation
Keasel Eric
Nixon & Vanderhye PC
Shaver Kevin
LandOfFree
Flow control valve does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flow control valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flow control valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2532440