Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
1999-11-08
2001-05-15
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S120000, C251S121000, C138S044000
Reexamination Certificate
active
06231029
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an anti-lock brake system, and more particularly, to a solenoid valve for an anti-lock brake system that can enhance a braking performance by variably controlling an amount of fluid to be supplied during a slip control.
2. Description of Related Art
Generally, a brake system comprises a wheel cylinder mounted on an automotive wheel to generate braking force using hydraulic pressure, a booster/master cylinder assembly for forming hydraulic pressure and applying the same to the wheel cylinder, and a modulator for controlling the hydraulic pressure to be supplied according to a running condition of a vehicle in accordance with signals transmitted from an electronic control unit.
The modulator is equipped with normal-open and normal-close solenoid valves for controlling the supply of braking pressure. The normal-open solenoid valve is designed to, in a normal brake mode, maintain an opened state to supply hydraulic pressure to the master cylinder without pressure reduction, and in a slip control mode, control an amount of the hydraulic oil to control the braking pressure.
The normal-open solenoid valve controls an amount of the hydraulic oil by a simple On/Off operation of a plunger. Accordingly, the flow rate of the hydraulic oil which can pass through the valve at the slip control mode is the same as at the normal brake mode.
Therefore, in such a conventional normal-open solenoid valve, an amount of the hydraulic pressure to be supplied cannot be precisely controlled, making it difficult to accurately perform a slip control. Furthermore, a water hammering phenomenon occurs by pulsations of fluid due to the plunger's movement to open and close positions, thereby generating noises and deteriorating the durability of parts.
To solve the above described problems, a normal-open solenoid valve which is designed to reduce an amount of the fluid to be supplied to the wheel cylinder in proportion to a slip rate, while alleviating the pulsations of the fluid during a slip control, has been developed.
As shown in
FIG. 1
, an example of such a normal-open solenoid valve is disclosed in the U.S. Pat. No. 5,647,644, which comprises a valve seat
23
, a magnetic core
21
, a plunger
22
, and a piston
24
, all of which are installed in a valve housing
20
. The valve seat
23
is forcedly fitted in a lower portion of the valve housing
20
and provided with a longitudinal through hole. The plunger
22
is mounted passing through the magnetic core
21
such that a lower end thereof is disposed in the vicinity of the top of the valve seat
23
. The piston
24
is disposed around the valve seat
23
and biased against the magnetic core
21
by a spring
25
.
The normal-open solenoid valve is provided with two orifices, one of which is an invariable orifice formed on an upper end of the valve seat
23
and the other of which is a variable orifice
40
that is defined by a slot
26
formed on the top of the piston
24
when the piston
24
contacts the magnetic core
21
during a slip control.
In addition, a hydraulic channel branch
31
is defined between one side wall of the valve seat
23
and the valve housing
20
so that hydraulic pressure supplied through an inlet
27
can be applied to the piston
24
through the hydraulic channel branch
31
, thereby displacing the piston
24
upward while overcoming the biasing force of the spring
25
. A stepped portion
23
a
is formed on another lower side of the valve seat
23
so as to forcedly fit the valve seat
23
into the valve housing
20
.
In the normal brake mode, the plunger
22
is urged upward while the piston
24
is biased downward by the spring
25
. Therefore, hydraulic oil is supplied through the inlet
27
, then directed to an outlet
28
through the invariable orifice
30
.
In the slip control mode, the plunger
22
is displaced downward to close the invariable orifice
30
. As a result, the hydraulic oil supplied through the inlet
27
is applied to the piston
24
through the hydraulic channel branch
31
so that the top of the piston
24
contacts the magnetic core
21
by being moved upward while overcoming the elastic force of the spring
25
. After this, when the plunger
22
is moved upward, the hydraulic pressure generated by the master cylinder is directed to the wheel cylinder through the variable orifice
40
formed by the slot
26
of the piston
24
contacting the magnetic core
21
.
When the braking force is released, the hydraulic oil within the wheel cylinder is returned to the master cylinder through the return passage
29
formed passing through the valve housing
20
to communicate the inlet
27
with the outlet
28
. After this, the plunger
22
is moved upward so that the solenoid valve is returned to its open state.
However, in the above-described normal-open solenoid valve, since the lower portion of the valve seat is designed to have the stepped portion and the channel branch defining portion, and the channel branch defining portion should be precisely formed, it is difficult to manufacture the valve seat.
In addition, since the special valve housing for receiving the magnetic core, the valve seat, the piston and the fluid passages is required, the entire size of the solenoid vlave is increased.
SUMMARY OF THE INVENTION
Therefore, this invention has been made in an effort to solve the above described problems.
It is an object of this invention to provide a solenoid valve for an anti-lock brake system, which can vary an amount of hydraulic oil to be supplied during a slip control.
It is another object of this invention to provided a solenoid valve, which is simple in the structure and easy to be manufactured by forming oil passages and two orifices using a valve seat and a piston.
To achieve the above objectives, this invention provides a solenoid valve comprises a magnetic core, a plunger and a piston is mounted on the modulator of an anti-lock brake system.
The magnetic core is inserted into a bore provided to the modulator, and has a plunger hole formed extending from its upper end to its middle, an inlet passage provided to its lower end from its middle, an outlet passage provided at the lower end of the plunger hole, and an invariable orifice allowing the inlet passage to communicate with the outlet passage.
The piston is provided to the inlet passage in such a manner that it is movable up and down, and has an eccentric hole formed vertically passing through its interior, thus forming a variable orifice along with a lower end of the invariable orifice.
The inlet passage has a small-diameter portion and a large-diameter portion on its upper and lower areas, respectively, and the piston is of a diameter of a nearly same size as the small-diameter portion, and has a support jaw having a nearly same diameter as the large-diameter portion on its lower end.
As a first embodiment of this invention, the piston has a groove on its top surface to allow the eccentric hole to communicate with the invariable orifice.
As a second embodiment of this invention, a protruding jaw, in place of the groove, is provided to the lower end of the invariable orifice to allow the eccentric hole to communicate with the invariable orifice.
As a third embodiment of this invention, a recess, in place of the groove, is provided to the lower end of the invariable orifice to allow the eccentric hole to communicate with the invariable orifice.
The magnetic core has a through hole formed slanting upward to its one side from the large-diameter portion of the inlet passage.
A lip seal is formed between the outer periphery of the magnetic core and the bore of the modulator to prevent oil from flowing to the direction of the outlet passage.
REFERENCES:
patent: 2984261 (1961-05-01), Kates
patent: 2992808 (1961-07-01), Burritt Jr. et al.
patent: 3006378 (1961-10-01), Erickson et al.
patent: 3332436 (1967-07-01), Welty
patent: 3645494 (1972-02-01), Stelzer
patent: 4024889 (1977-05-01), Smith et al.
patent: 4383552 (1983-05-01), Baker
patent: 4384592 (1983-05-
Bonderer David A.
Ladas & Parry
Mando Machinery Corporation
Shaver Kevin
LandOfFree
Solenoid valve for anti-lock brake system 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 for anti-lock brake system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solenoid valve for anti-lock brake system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2498667