Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2000-02-17
2001-08-14
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S337000, C267S180000
Reexamination Certificate
active
06273396
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Application No. H.11-85612 filed on Mar. 29, 1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic valve, in particular, applicable to a canister for processing vaporized fuel to be emitted from an automobile fuel tank.
2. Description of Related Art
Conventionally, a vehicle using gasoline as fuel has been provided with a vaporized fuel processing system for preventing vaporized fuel of a fuel tank from emitting into an air. This system has, as shown in
FIG. 4
, a canister
2
for adsorbing and holding vaporized fuel to be emitted from a fuel tank
4
and an electromagnetic valve
1
disposed at a air port
8
of the canister
2
.
The electromagnetic valve
1
carries out a predetermined valve opening and closing operation, as shown in
FIG. 5
, when a leak check of the system is conducted. As shown in
FIG. 8
, the electromagnetic valve
1
is composed of a valve body
120
for opening and closing an air communication path
110
provided in a housing
100
, a spring
130
for biasing the valve body
120
in a valve opening direction (right direction in
FIG. 8
) and an electromagnetic device
140
for driving the valve body
120
against a biasing force of the spring
130
. The electromagnetic valve
1
is normally at a valve opening state when the electromagnetic device
140
is turned off (at a state shown in FIG.
8
).
The operation of the electromagnetic valve
1
at the leak check is described below. When a built-in coil
150
of the electromagnetic device
140
is energized for leak check, a moving element
170
arranged at an internal circumference of a bobbin
160
is attracted in a left direction of the drawing. Thus, the valve body
120
is pushed out in a left direction of the drawing together with a retainer
180
assembled to the moving element
170
so that a valve opening
190
of the air communication path
110
may be closed.
When the coil
150
is de-energized to finish the leak check, the valve body
120
closing the valve opening
190
is pushed back to open the valve opening
190
by the biasing force of the spring
130
, since the attracting force applied to the moving element
170
is eliminated. As a result, the valve body
120
is moved back and stopped at a predetermined position where a right side end of the retainer
180
comes in contact with a left side surface
161
of the bobbin
160
.
In case of the conventional electromagnetic valve, the valve body
120
is abruptly pushed back by an elastic force stored at the spring
130
to cause the end of the retainer
180
to hit the side surface of the bobbin
160
with a hammer noise.
If the leak check is conducted during a vehicle running period when the road noises are prevailing, a generation of the hammer noise does not bring a big problem because the hammer noise can be drowned out by the road noises. However, if the leak check is conducted during a vehicle stopping period when road noises are not generated, for example, at an idling period, the generation of the hammer noise might result in a big problem because a driver hears as an abnormal and annoying sound the hammer noise not drown out by the road noises.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above mentioned problem, and an object of the present invention is to eliminate a hammer noise to be generated according to the opening/closing operation of the electromagnetic valve.
To achieve the above object, the electromagnetic valve for opening and closing a fluid communication path has a valve body capable to open and close the fluid communication path, a first spring for biasing the valve body in a valve opening direction and a second spring opposed to the first spring for biasing the valve body in a valve closing direction. A biasing force of the first spring toward the valve body is balanced with a biasing force of the second spring toward the valve body so that the valve body may stay or stand still at a predetermined position to open the communication path. A moving member of an electromagnetic device is driven, when a coil of the electromagnetic device is energized, so as to have the valve body move against the biasing force of the first spring during a first moving stroke extending from the predetermined position to a position where the valve body closes the fluid communication path so that an elastic energy may be stored in the first spring during the first moving stroke.
On the other hand, the valve body is moved back together with the moving member, when the coil is de-energized, by the first spring not only during the first moving stroke but also during a second moving stroke extending from the predetermined position to a position where the second spring stores an elastic energy practically responsive to the elastic energy stored in the first spring during the first moving stroke. In this case, there is an enough space where the valve body and the moving member may move back during the second moving stroke so as not to hit any part of the electromagnetic device.
According to the electromagnetic valve mentioned above, a total moving stroke of the valve body is longer by the second moving stroke than that of the conventional electromagnetic valve in which the end of the retainer hits the side surface of the bobbin so as to stop a return movement of the valve body.
It is more preferable, therefore, that the second spring has a non-linear load characteristic so that the second moving stroke may be shorter than the first moving stroke. With the construction mentioned above, the total moving stroke of the valve body becomes shorter, compared with a case that the second spring has a linear road characteristic same as that of the first spring. As a result, the electromagnetic valve may be realized not only with a more compact construction but also with a stronger electromagnetic attracting force for attracting the moving member.
Preferably, the second spring is a coil spring or a plate spring with a non-linear road characteristic so that the elastic energy stored in the first spring during the first moving stroke may be absorbed by the second spring with a less distance movement in an elastic direction.
The coil spring of the second spring may be formed in an unequal pitch shape to be coiled more finely at both end portions than a center portion, at a center portion than both end portions or at a side than the other side. Preferably, the spring is shaped symmetric in its elastic directions so that the spring may be assembled to the electromagnetic valve without care of its assembly direction.
The electromagnetic valve according to the present invention is, preferably, applied to a vehicle. Even if the coil is energized during a vehicle stopping period when road noises do not exist, the valve body may be moved to close and open the fluid communication path without a hammer noise that is annoying to a driver.
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Bastianelli John
Denso Corporation
Nixon & Vanderhye PC
Shaver Kevin
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