Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
2002-04-09
2004-04-06
Bastianelli, John (Department: 3754)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C251S129150, C251S333000, C239S585100, C303S119200
Reexamination Certificate
active
06715700
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a solenoid valve used in an electronically controlled vehicle hydraulic brake system. More particularly, it relates to a solenoid valve which suppresses sound and vibration produced during operation and which scarcely malfunctions.
FIG. 2
shows an example of an electronically controlled vehicle hydraulic brake system. It is designed for antilock control. When the driver depresses the brake pedal
1
, the force is amplified by a booster
2
, a master cylinder
3
is actuated by the force, so that pressurized brake fluid is supplied to wheel cylinders
4
, thereby producing braking force.
In a flow passage from the master cylinder
3
to the wheel cylinders
4
, normally open solenoid valves
5
are provided. Also, between the wheel cylinders
4
and low-pressure fluid reservoirs
6
, normally closed solenoid valves
7
are provided. Further, there are provided motor-driven pumps
8
for sucking brake fluid in the low-pressure fluid reservoirs
6
and returning it to a flow passage upstream of the solenoid valves
5
(i.e. master cylinder side), and orifices
9
for suppressing pulsation of the fluid discharged from the pump.
In such a brake system, if an electronic control unit (not shown) detects a sign of wheel locking based on information from e.g. a wheel speed sensor (not shown), it will give a command to close the solenoid valve
5
and open the solenoid valve
7
in the line to which the wheel belongs, thereby reducing the pressure of the wheel cylinder
4
. Also, when the electronic control unit determines that as a result of the pressure reduction, the system is showing a tendency to recover from wheel locking, the solenoid valves
5
and
7
are opened and closed, respectively. Brake fluid sucked up by the pump
8
is supplied to the wheel cylinder
4
to reincrease pressure. By repeating this operation, wheel locking is avoided.
FIG. 3
shows a specific example of a solenoid valve
5
employed in the hydraulic brake system of FIG.
2
. It comprises a frame
51
, a poppet
52
mounted in a bore of the frame, an orifice
54
having a valve seat
53
, a spring
55
, a solenoid
56
for applying a valve-closing force to the poppet
52
, and a housing
57
coupled to the frame
51
. When the coil
56
a
of the solenoid
56
is energized, a movable core
56
b
integral with the rear end of the poppet
52
is attracted toward the frame
51
by a magnetic force produced, so that the poppet
52
contacts the valve seat
53
, which is provided at a mouth portion of the orifice
54
, thereby closing the valve.
Also, when the solenoid
56
is demagnetized, the poppet
52
will move away from the valve seat
53
under the force of the spring
55
, so that the valve opens. Brake fluid flows from an input port
59
through the orifice
54
, and then through an open passage between the valve seat
53
and the poppet
52
into an output port
58
.
With a solenoid valve in which the flow passage is opened and closed by a poppet, when the valve is closed, the poppet
52
collides against the valve seat, and when the valve is opened, the movable core
56
b
collides against the housing
57
. Thus operating sounds are big.
Also, since changes in the degree of opening of the flow passage with the movement of the poppet are large, brake fluid pulsates during opening and closing. This increases vibration inflicted on the vehicle.
An object of this invention is to suppress sound and vibration and to eliminate malfunction of solenoid valves.
SUMMARY OF THE INVENTION
According to this invention, there is provided a solenoid valve comprising a poppet, an orifice, a valve seat provided at a mouth portion of the orifice, a solenoid for bringing the tip of the poppet into contact with the valve seat by applying a valve-closing force to the poppet, and a spring for applying a force in a valve-opening direction to the poppet, whereby a flow passage around the valve seat is opened and closed by the poppet and the fluid to be controlled is allowed to flow through the valve while the valve is open, characterized in that the following conditions are satisfied,
F
SP
/(
r
2
−B
2
)<67 (1)
F
SP
·St
2
/(
r
2
−B
2
)>29 (2)
wherein F
SP
is the force of the spring, r is the tip diameter of the poppet, St is the stroke of the poppet, and B is the diameter of the area of the poppet where the valve-opening force by hydraulic pressure does not work on the poppet under the Bernoulli effect.
With such a solenoid valve in which the poppet tip diameter is 1.2 to 1.8 mm, the orifice diameter is 0.7 mm, and the angle of the seat surface of the valve seat is 120°, if the spring force F
SP
and the poppet stroke St are so set as to satisfy the above formulas with the value of B set at 1.1 mm, better results are obtained.
More preferably, the following conditions
F
SP
/(
r
2
−B
2
)<48
F
SP
·St
2
/(
r
2
−B
2
)>40
are both satisfied.
With the solenoid valve of this invention, when the valve is opened during hydraulic pressure control, poppet suction force will be generated due to the Bernoulli effect, so that the poppet is kept in a half-open position. This restrict sharp movement of brake fluid, so that pulsation during opening and closing of the valve decreases. Also, since the poppet stops at a half-open position, impulsive collision of the movable core against the housing and impulsive collision of the poppet against the valve seat are prevented, so that operation sound decreases.
In order to obtain such sound/vibration suppression effect, formula (1) is satisfied. Also, since ones that malfunction were found among ones that satisfy formula (1), in order to eliminate them, formula (2) should also be satisfied. How formulas (1) and (2) have been derived will be described below.
From the Bernoulli's theorem
½
&rgr;&ngr;
2
+P+&rgr;gz
=constant
&rgr;: fluid density g: acceleration of gravity
p: fluid pressure z: height from reference surface
&ngr;: absolute value of flow rate vector
Assuming that &rgr;, g and z are constant,
&Dgr;P=&rgr;&ngr;
2
/2
On the other hand, the suction force acting on the poppet is:
F
=
Δ
P
·
A
1
(
A
1
:
pressure
receiving
area
of
poppet
)
=
ρν
2
/
2
·
A
1
=
ρ
(
Q
/
A
2
)
2
·
A
1
/
2
(
Q
:
flow
rate
A
2
:
flow
passage
area
)
=
ρ
Q
2
/
2
·
A
1
/
A
2
2
&AutoLeftMatch;
Here, considering that around the center of the poppet, the valve-opening force by hydraulic pressure is canceled by Bernoulli effect and assuming that the diameter of this range is B,
A
1
=K
1
(
r
2
−B
2
)
Supposing that A
2
is proportional to stroke St,
A
2
=K
2
·St
Ignoring changes in &rgr; and Q,
F=K
·(
r
2
−B
2
)/
St
2
Here, if F
SP
<F, it is possible to suppress sound and vibration by keeping the poppet in a half-open position. Thus,
F
SP
<K·
(
r
2
−B
2
)/
St
2
Since the stroke is irrelevant to the sound/vibration suppression,
F
SP
/(
r
2
−B
2
)<
K
Also, since malfunction of the solenoid valve will not occur if the spring force F
SP
>F,
F
SP
>K·
(
r
2
−B
2
)/
St
2
F
SP
·St
2
/(
r
2
−B
2
)>
K
Based on this thought, with a solenoid valve having the structure of FIG.
3
and having an orifice diameter d of 0.7 mm, a seat angle &thgr; of the valve seat of 120°, a poppet tip diameter r of 1.2 to 1.8 mm, evaluation was made while changing the spring F
SP
and stroke St. As a result, ones that satisfy formula (1) are small in sound and vibration, and ones that satisfy both formulas (1) and (2) are free of malfunction, so that it was possible to confirm the effects achieved by satisfying both formulas (1) and (2).
Other features and objects of the present inven
Nakano Keita
Okamura Koichi
Bastianelli John
Greenblum & Bernstein P.L.C.
Sumitomo (SEI) Brake Systems, Inc.
LandOfFree
Solenoid 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 Solenoid valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solenoid valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3267383