Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2003-12-31
2004-11-02
Hirsch, Paul J. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129010
Reexamination Certificate
active
06811137
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a solenoid valve used suitably for pressure control of various fluids or the like.
BACKGROUND ART
Conventionally, a solenoid valve of this type is shown in, for example, FIG.
7
.
FIG. 7
is a schematic, cross sectional view showing a construction of a solenoid valve of the conventional art.
A solenoid valve
200
comprises a solenoid section
200
A and a valve section
200
B.
Here, the valve section
200
B comprises a spool valve constructed such that since an opening area of the valve is varied according to a stroke of a spool, a solenoid controls a stroke amount of the spool to be able to control an amount of inflow and an amount of outflow.
The solenoid section
200
A generally comprises a coil
203
, a plunger
201
adapted to be magnetically attracted to a center post
202
upon energization of the coil
203
, and a rod
204
connected to the plunger
201
to transmit driving of the plunger
201
to the valve section
200
B (concretely, the spool), a casing member
208
, into which various solenoid constituents are incorporated, and a connector
211
for feeding electricity to the coil
203
.
Also, a first bearing
205
and a second bearing
210
for increasing a coaxiality of the plunger
201
and the rod
204
, which reciprocate, are provided, and the rod
204
fitted into the plunger
201
is supported by the bearings
205
,
210
, one of the bearings
205
being supported by a sleeve
206
. The other of the bearings
210
is supported by the center post
202
. Also, provided are an upper plate
207
, which forms a magnetic path, and the like.
Here, the plunger
201
is configured to be positioned in a direction away from the center post
202
in a normal state, that is, a state, in which electricity is not fed to the coil
203
.
In addition, generally, a biasing member such as springs, or the like, biases the plunger
201
in a direction away from the center post
202
. In an example shown, a spring for biasing the spool toward the solenoid section
200
A is provided whereby the plunger is spaced away from the center post
202
through the spool.
So, electricity is fed to the coil
203
to thereby form a magnetic path, so that the plunger
201
is magnetically attracted to the center post
202
.
Accordingly, magnetic forces can be controlled according to a magnitude of current fed to the coil
203
, so that an amount of movement of the plunger
201
is controlled to enable controlling an amount of stroke of the spool, thus enabling controlling a flow rate of a fluid, pressure control, such as hydraulic control, of various fluids, or the like.
Here, the solenoid valve
200
of the conventional art is assembled by suitably incorporating various solenoid constituents, which include the plunger
201
and the center post
202
, in a hollow portion of the substantially cylindrical-shaped casing member
208
from both end sides of the casing member
208
according to shapes, or the like, of the respective member, thereafter caulking a caulked portion
208
a
, which is provided on one end side of the casing member
208
, on an end of the upper plate
207
and further caulking a caulked portion
208
b
, which is provided on the other end side, on an end of the valve section
200
B (however, the caulked portion
208
a
is not always caulked first in a caulking order).
Hereupon, in the case where the connector
211
is of a type to be arranged in a portion of a rear end of a solenoid valve body in a circumferential direction as in the solenoid valve
200
of the conventional art shown in
FIG. 7
, there is involved a disadvantage that interchangeability is bad since the positional relationship between the connector and a bracket
212
for mounting the solenoid valve body in a predetermined mount position must be modified according to a mount location.
Here, in order to improve interchangeability, there is known a type, in which a connector
311
is disposed on a rear end of a body of a solenoid valve
300
to project outside from one end of a casing member
308
as shown in FIG.
9
.
In this case, since the connector
311
is structured to project outside from one end of the casing member
308
to be disposed on an axis, there is no need of taking account of the positional relationship between the connector and a bracket, which makes interchangeability excellent.
In the case of this type, assembly is performed by forming a step portion
311
a
on the connector
311
, which is molded by insert molding of a connector terminal, and caulking a caulked portion
311
a
, which is provided on one end of the casing member
308
, on the step portion
311
a.
Here, since that portion, in which a metallic upper plate
312
is formed integral with a resin material, involves a relative difference in coefficient of linear expansion between the resin and the metal, a gap is liable to be produced due to repeated thermal expansion and contraction (temperature change).
Also, that portion, in which the resin is fixed by caulking of the casing, is liable to generate a gap because the caulked portion is partially strained.
Therefore, a seal ring O is provided in order to prevent water from entering into a coil from outside through the gap to generate such malfunction as short circuit, or the like.
DISCLOSURE OF THE INVENTION
As described above, with the solenoid valve of the conventional art, various solenoid constituents must be assembled into the casing member
208
from both sides thereof, and so the casing member
208
must be suitably reversed in the assembling process, which causes an increase in manhour for assembly and complexity in the assembling work.
Also, since various solenoid constituents must be assembled from the both sides, a caulking processing is necessary in two locations on the both sides in order to provide fixing of the various constituents.
In addition, in the case where a seal ring is to be assembled to an inner periphery of the casing member, when the seal ring remains long in a state, in which it slides on and contacts with an inner periphery of the casing member, at the time of assembly, there is a fear that abrasion of the seal ring and worsening of a mount state, such as distortion of the seal ring, are caused to degrade the sealing performance, and so there is a demand for prevention of such matter.
Also, accuracy in inner diameter and accuracy in surface condition are demanded for those portions, against which the seal ring abuts, and an outer periphery of the upper plate consituting a magnetic flux feeding portion abuts, in an inner peripheral portion of the casing.
Also, the above conventional art involves a problem that bearings cause shaft deviation to lead to lowering of accuracy in coaxiality. Here, coaxiality means positional accuracies of a plunger and a rod, which move reciprocatingly in an axial direction. That is, the closer to a central axis of the whole solenoid valve axes of a plunger and a rod making reciprocation, the higher these accuracies. Such coaxiality is determined by positional accuracies among respective members, and in particular, when bearings cause shaft deviation, accuracy in coaxiality is lowered.
In this manner, when bearings cause shaft deviation and accuracy in coaxiality is lowered, a plunger and a rod are increased in sliding resistance, which is responsible for degradation in function, such as generation of hysteresis, or the like.
As the reason for causing shaft deviation, it is first cited that a caulked portion is near a portion, by which an outer periphery of the plate is held.
That is, the casing is liable to be susceptible of deformation in the vicinity of the caulked portion, and that member, on which load of caulking is applied, becomes liable to be susceptible of positional deviation.
Meanwhile, the plate is generally a member that affects positional accuracies of various constituents constituting a solenoid much. This is because a sleeve and the like are joined integrally to the plate and the plate positions bearings through other several members. Also, the plate is positi
Hirata Ichiro
Kasagi Yoshinari
Uemura Norio
Hirsch Paul J.
Jacobson & Holman PLLC
NOK Corporation
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