Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-09-24
2002-07-02
Dickson, Paul N. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C137S596100
Reexamination Certificate
active
06412884
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a solenoid-controlled valve suitable for use in hydraulic controllers for brakes, for example, an anti-lock brake controller.
One example of conventional solenoid-controlled valves is disclosed in Japanese Patent Application Unexamined Publication (KOKAI) No. 7-144629 (1995). U.S. Pat. Nos. 5,577,815 and 5,609,400 correspond to this Japanese literature. The solenoid-controlled valve has a housing, both ends of which are closed. The housing has a first port and a second port which are provided in a side wall thereof in series from one end toward the other end. A third port is provided at the other end of the housing. A first valve body slides in the housing in a longitudinal direction to bring the first and second ports into and out of communication with each other. A second valve body is placed in the housing so as to be movable in the longitudinal direction to bring the second and third ports into and out of communication with each other. A first spring (first urging member) is interposed between the one end of the housing and the first valve body to urge the first valve body in a valve opening direction. A second spring (second urging member) is interposed between the second valve body and a reduced-diameter portion formed in the housing between the first and second ports to urge the second valve body in a valve closing direction. An electromagnetic force generating device is provided at the one end of the housing. A movable member is engaged with the first and second valve bodies and moved in the housing in the longitudinal direction by an electromagnetic force from the electromagnetic force generating device against urging forces of the first and second springs to cause the first and second valve bodies to move to valve opening or closing positions. The solenoid-controlled valve operates as follows:
{circumflex over (1)} When there is no electromagnetic force from the electromagnetic force generating device, the first valve body is placed in the valve opening position by the urging force of the first spring, and the second valve body is placed in the valve closing position by the urging force of the second spring.
{circumflex over (2)} When the electromagnetic force of the electromagnetic force generating device is set to a first predetermined value, the movable member causes the first valve body to move to the valve closing position against the urging force of the first spring, and the second valve body is placed in the valve closing position by the urging force of the second spring.
{circumflex over (3)} When the electromagnetic force of the electromagnetic force generating device is set to a second predetermined value larger than the first predetermined value, the movable member causes the first valve body to move to the valve closing position against the urging force of the first spring and also causes the second valve body to move to the valve opening position against the urging force of the second spring.
Incidentally, to move the first valve body to the valve closing position in the above-described prior art, it is necessary to generate an electromagnetic force that is sufficiently large to move the first valve body against the urging force of the first spring. To move the second valve body to the valve opening position, it is necessary to generate an electromagnetic force that is large enough to move the second valve body against the urging forces of the first and second springs. Accordingly, the prior art needs to prepare a coil enduring a large electric current or a coil with a large number of turns, resulting in an increase in size of the apparatus. This may make it difficult to ensure a space for installation and also cause an increase in the battery capacity.
With a view to facilitating understanding of the present invention, the known solenoid-controlled valve disclosed in the above-mentioned Japanese Patent Application Unexamined Publication (KOKAI) No. 7-144629 (1995) will be described below with reference to
FIGS. 8 and 9
(first prior art) and
FIGS. 10 and 11
(second prior art).
As shown in
FIG. 8
, a solenoid-controlled valve
1
according to the first prior art has a cylinder
4
formed with three ports
3
a
,
3
b
and
3
c
communicating with a cylinder bore
2
. Of the three ports
3
a
,
3
b
and
3
c
, two ports are formed in a side wall of the cylinder
4
, and the other port is formed in a bottom (right-hand end as viewed in
FIG. 8
) of the cylinder
4
. For the sake of convenience, the ports formed in the side wall of the cylinder
4
are referred to as “a-port
3
a
and b-port
3
b
”, and the port formed in the bottom as “c-port
3
c
”.
A spool
7
is provided in the cylinder bore
2
so as to be movable with respect to the a-port
3
a
. The spool
7
has an insertion bore
5
and a passage (spool passage)
6
. The spool passage
6
communicates with the insertion bore
5
at one end thereof and opens on the side surface of the spool
7
at the other end thereof. In addition, a poppet valve
8
with an approximately C-shaped sectional configuration is provided in the cylinder bore
2
so as to be movable with respect to the c-port
3
c.
A solenoid
9
is provided at one end of the cylinder
4
. A shaft-shaped movable member
10
is provided in such a manner as to be inserted into the solenoid
9
. The movable member
10
is driven by the solenoid
9
.
The movable member
10
extends through the insertion bore
5
of the spool
7
to reach a hollow portion (no reference numeral) of the poppet valve
8
. A projection (referred to as “first projection”)
12
is formed at the distal end of the movable member
10
. The first projection
12
is engageable with a wall portion
11
of an opening of the poppet valve
8
. Another projection (referred to as “second projection”)
13
is formed on an intermediate portion of the movable member
10
. The second projection
13
is engageable with the spool
7
.
A spring (first spring)
15
is interposed between the spool
7
and a step portion
14
formed at one end of the cylinder bore
2
. The first spring
15
urges the spool
7
toward the other end of the cylinder bore
2
. A spring (second spring)
17
is interposed between the poppet valve
8
and a spring retaining portion
16
projecting inward in the cylinder bore
2
between the a-port
3
a
and the b-port
3
b
. The second spring
17
presses the poppet valve
8
against the c-port
3
c.
When the solenoid-controlled valve
1
is not energized, the a-port
3
a
and the passage
6
in the spool
7
are in communication with each other (i.e., the spool
7
is in a valve opening position), and the poppet valve
8
is in a position where it closes the c-port
3
c.
The movable member
10
is displaced according to the value of electric current supplied to the solenoid
9
. According to the amount of displacement (stroke) of the movable member
10
, valve opening and closing modes of the spool
7
and the poppet valve
8
are changed over as shown in Table 1 below.
FIG. 9
shows the relationship between the stroke and the spring force in the operation of the solenoid-controlled valve
1
according to the first prior art.
TABLE 1
First
Second
Third
Current
Non-
reference
reference
reference
value
energized
range
range
range
Stroke
S
0
S
0
to S
1
S
1
to S
2
S
2
to S
3
Spool 7
Open
Closed
Closed
Poppet
Closed
Closed
Open
valve 8
Valve
First mode
Second
Third mode
opening &
mode
(final stage)
closing mode
In FIG.
9
and Table 1: stroke S
0
shows an initial position; S
1
shows a position where the a-port
3
a
is closed; S
2
shows a position where the first projection
12
is engaged with the poppet valve
8
; and shows a predetermined stroke position exceeding S
2
. The current value increases as the reference range shifts from the first to the second and further to the third.
As shown in
FIG. 9
, in the stroke range of S
0
to S
2
, the first spring
15
increases in spring force as the stroke becomes longer, whereas the second spring
17
exhibits a constant spring force independ
Matsunaga Kunihiro
Sakuma Masaru
Takayama Toshio
Dickson Paul N.
King Bradley
Tokico Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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