FLUID-BIASED HYDRAULIC CONTROL VALVE WITH ARMATURE PISTON
TECHNICAL FIELD
[0001) The present invention relates to an electrically-operated hydraulic control
mechanism such as a solenoid valve.
BACKGROUND OF THE INVENTION
[0002] Solenoid control valves for hydraulic control systems are used to control
oil under pressure that may be used to switch latch pins in switching lifters and lash
adjusters in engine valve systems. Valve lifters are engine components that control the
opening and closing of exhaust and intake valves in an engine. Lash adjusters may also
be used to deactivate exhaust and intake valves in an engine. Engine valves may be
selectively deactivated or locked out to disable operation of some cylinders in an engine
when power demands on an engine are reduced. By deactivating cylinders, fuel
efficiency of an engine may be improved.
[0003] Engine deactivating solenoid control valves must operate with rninimum
response times to maximize engine efficiency and prevent engine damage. Valve
response times include valve activation response times and deactivation response times.
Solenoid control valves apply a magnetic force to an armature that moves a control valve
stem by activating a coil to move the armature against a biasing force that is typically
provided by a spring. Typically, a greater magnetic force applied by the solenoid will
reduce response time. The magnetic force applied by the coil can be increased by
increasing the size of the coil. However, cost, available space, and weight reduction
considerations tend to limit the size of the coil.
SUMMARY OF THE INVENTION
[0004] A hydraulic control valve is configured to be operable with a relatively
inexpensive coil by reducing the effective pressure area on which pressurized fluid acts to
create a biasing force that must be overcome by magnetic force generated by the coil to
move the valve to an energized position. Specifically, the valve includes a solenoid
body, a selectively energizable coil, and an armature positioned adjacent the coil. The
coil is energizable to generate a magnetic force that moves the armature from a first
position to a second position. A pole piece is positioned to establish a gap between the
pole piece and the armature. The pole piece has a cavity that opens at the gap. A piston
extends from the armature into the cavity of the pole piece and moves with the armature.
The valve body, the armature, and the piston are configured so that the armature is biased
to seat at a valve seat in the first position by pressurized fluid. The magnetic force
required to move the armature away from the valve seat is a function of the difference
between an area of the piston and an area defined by contact of the armature at the valve
seat.
[0005] In one embodiment, the armature and the valve stem include a first poppet
and a second poppet, and the valve body defines a supply chamber with a first seat (i.e.,
the valve seat), a second seat, and a control chamber between the first and second seats.
The first poppet is configured to sit at the first seat and the second poppet is configured to
be spaced from the second seat in the first position to prevent pressurized fluid flow past
the first seat and to exhaust fluid from the control chamber past the second seat. The first
poppet is configured to be spaced from the first seat and the second poppet is configured
to sit at the second seat in the second position to permit flow of pressurized fluid from the
supply chamber to the control chamber and prevent flow from the control chamber to the
exhaust chamber.
[0006] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of the
best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGURE 1 is a perspective view of a solenoid valve;
[0008] FIGURE 2 is an exploded perspective view of the solenoid valve shown in
Fig. 1;
[0009] FIGURE 3 is a cross-sectional view taken along the plane of section line
3-3 in Fig. 1 showing the valve in a first, closed and deenergized position; and
[0010] FIGURE 4 is a partial cross-sectional view similar to Figure 3 of the valve
in a second, open and energized position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] Fig. 1 illustrates a solenoid valve 10, for example, such as that used to
deactivate lifters or operate a dual lift system in an internal combustion engine or diesel
engine. The solenoid valve 10 may also be referred to as a hydraulic control valve or as
an electromagnetic actuator. The solenoid valve 10 is installed in an engine 12. The
solenoid valve 10 includes a solenoid portion 16 and a valve body 18.
[0012] Figs. 2 and 3 shows the solenoid valve 10 having a solenoid can 20 that
houses a coil 22 that powers the solenoid valve 10. A pole piece 24 is assembled within
the solenoid can 20. The pole piece 24 defines part of the flux path for the solenoid 16. A
flux collector insert 26 is disposed within the solenoid can 20 and also forms part of the
flux path for the solenoid 16.
[0013] An armature 28 is acted upon by the flux created by energizing the coil 22
to shift the solenoid valve 10 from a normally closed (first) position as shown in Fig. 3 to
the open (second) position as shown in Fig. 4. An air gap 30 is provided between a
radially-extending face 32 of the pole piece 24 and a radially-extending face 33 of the
armature 28. The air gap 30 may be adjusted by adjusting the pole piece 24 relative to
the armature 28. A relief groove 34, shown in Fig, 2, is provided in the armature 28 to
facilitate the flow of oil under pressure axially along the armature 28. The relief groove
34 is also referred to as a conduit. Alternatively, a conduit may be formed in the valve
body 18 adjacent the armature 28 to provide flow of pressurized oil across the armature
28. The flux collector insert 26 may be inserted adjacent to the coil 22 and the valve
body 18 in a molded one-piece or multiple-piece body 40.
[0014] Referring to Fig. 3, a piston 29 is press-fit or otherwise secured in an
opening 31 defined by the armature 28 so that the piston 29 extends from and moves with
the armature 28. The piston 29 also extends into a cavity 35 formed in the pole piece 24.
A head 37 of the piston 29 slides within the cavity 35 when the armature 28 moves, and
is configured so that an oil seal 39 is maintained between the piston 29 and the pole piece
24. The piston 29 is a non-magnetic material so that magnetic flux is not transmitted
from the armature 28 along the piston 29, thereby maintaining the effectiveness of the air
gap 30.
[0015] Optionally, a spring 45 is housed in the cavity 35 between the piston 29
and the pole piece 24. The spring 45 biases the armature 28 to the first, unenergized
position discussed below. Another opening 47 is provided in the pole piece 24 opposite
the gap 30 and opening into the cavity 35 to minimize or relieve pressure against
movement of the piston 29 toward the pole piece 24.
[0016] The valve body 18 defines an oil intake chamber 41, also referred to as a
supply chamber, in which the armature 28 is disposed and that initially receives oil under
pressure. The valve body 18 also defines an intermediate chamber 42, also referred to as
a control chamber. A plurality of O-ring grooves 43 are provided on the exterior of the
valve body 18 and each receives one of a plurality of seals 44. The seals 44 establish a
seal between the valve body 18 and the engine 12. The body 40 defines an internal coil
receptacle 46, or bobbin, that extends into the solenoid portion 16. The coil 22 is shown
only in part, but it is understood that the coil 22 fills the coil receptacle 46. The body 40
may be formed as a one-piece integral plastic molded part, as illustrated, or could be
formed in pieces and assembled together. The coil 22 is wrapped around the coil
receptacle 46.
[0017] A valve stem 48 has a portion 50 that is received within an opening 52 in
the armature 28. The position of the valve stem 48 may be adjusted relative to the
armature 28 by a threaded connection or by a press-fit between the stem 48 and the
armature 28. The armature 28 includes a poppet 54, referred to herein as a first poppet,
that is moved relative to valve seat 56 in response to pressure changes, as will be more
fully described below. An exhaust poppet 60, referred to herein as a second poppet, is
provided on one end of the control valve stem 48 to move relative to a valve seat 62 to
open and close an exhaust port 70. Valve seat 56 may be referred to herein as a first
valve seat and valve seat 62 may be referred to herein as a second valve seat.
[0018] A supply gallery 64 is provided in the engine 12 to provide pressure P1 to
the oil intake chamber 41 that is defined in the valve body 18. A control gallery 68 is
provided in the engine 12 that is normally maintained at control pressure P2. An exhaust
gallery 71, also provided in the engine 12, is in communication with the exhaust port 70
and is ported to ambient pressure and may be referred to as "P0". The intermediate
chamber 42 goes to pressure P0 when the exhaust port 70 is opened. The pressure at
opening 47 is also ambient pressure, P0.
[0019] Referring to Fig. 4, the solenoid valve 10 is shown in the open position.
The coil 22 is energized to retract the armature 28 toward the coil 22. The first poppet 54
opens the first valve seat 56 to provide pressure P1 from the oil intake chamber 41 to the
intermediate chamber 42, and the exhaust poppet 60 sits at seat 62 to close the exhaust
port 70.
[0020] Referring to Figs. 2-4, the valve body 18 includes a supply port or opening
63 that receives oil under pressure from the supply gallery 64 that is in communication
with the oil intake chamber 41 and the valve seat 56. When the valve seat 56 is open, the
intake chamber 41 is in communication with the intermediate chamber 42. Oil under
pressure is provided through an outlet opening 66, also referred to as a control port, and
to the control gallery 68.
[0021] In operation, the valve 10 is normally closed as shown in Fig. 3 and is
shifted to its open position as shown in Fig. 4 by energizing the coil 22. The coil 22,
when energized, reduces the air gap 30 formed between the pole piece 24 and the
armature 28. The armature 28 is shifted toward the pole piece 24 by electromagnetic flux
created by the coil 22. Oil in chamber 41 is in communication with the gap 30 through
the relief groove 34.
[0022] When in the normally closed position shown in Fig. 3, the poppet 54
closes the valve seat 56, isolating the oil intake chamber 41, which is at P1, from the
intermediate chamber 42, which is at P0. The oil under pressure in the oil intake chamber
41 biases the poppet 54 against the valve seat 56. Assuming the armature 28 and the
piston 29 are generally circular in cross-section, or have a cross-sectional area equivalent
to a circle, the area of face 33 has an annular shape and is the difference between the
cross-sectional area of the armature 28, represented as area A in Figure 2, and the cross-
sectional area A1 of the piston 29. An area A2 (see Fig. 2) is defined by a contact
diameter D2 at which the poppet 54 of the armature 28 contacts the valve seat 56.
Surface area 72 is referred to as cross-sectional area A3 in Fig. 2 and is defined by a
contact diameter D3 at which the poppet 60 contacts the valve seat 62. Although cross-
sectional areas described herein are assumed to be circular, the components establishing
the areas may have any shape with an effective area equal to that of a circle.
[0023] Force vectors acting on the valve 10 may be defined as follows:
Fm = magnetic force of the solenoid 16;
Fca = force on armature 28 to close after deenergizing the solenoid 16;
F1 = A1*P1=force of fluid at supply pressure on piston 29;
F2 = A2*P1=force of fluid at supply pressure on armature 28;
F03 = A2*P0=force in control chamber 42 before energizing the solenoid
16;
Fc3 = A2*P1=force in control chamber 42 during energizing of the
solenoid 16;
Fs = force of spring 45;
F4 = A1 *P0=atmospheric force on the piston 29;
F5 = control/supply force on the seat 62; and
F6 = atmospheric force on seat 62.
[0024] Accordingly, a force balance equation to move the valve 10 to open valve
seat 56 and close valve seat 62 is as follows:
Fm + Fl - F2 + F03 - F4 - Fs < 0,
assuming the valve 10 includes optional spring 45, and with forces acting in the same
direction as the magnetic force of the solenoid 10 being considered positive.
[0025] This is rewritten as:
Fm > -F1 + F2 -F03 + F4 + Fs,
and as
Fm > -(A1 * P1) + (A2 *P1) - (A2*P0) + (A1 * P0) + Fs.
Assuming that P0, atmospheric pressure, is zero, then:
Fm > -(A1 * P1) + (A2 *P1) + Fs.
Compare this to the magnetic force required when there is no piston 29:
Fm>(A2*P1) + Fs.
In both cases, Fs may be zero if no optional spring is used.
[0026] Thus by keeping the two diameters D1 and D2 relatively close in size, A1
and A2 are nearly equal, and the required magnetic force of the solenoid 10 necessary to
open the seat 54 reduces drastically. This allows a smaller, and therefore less expensive,
coil 22 to be used.
[0027] Similarly, a force balance equation to move the valve 10 to close valve
seat 56 and open valve seat 62 is:
Fca + F1 -F2 + Fc3-F4-F5 + F6-Fs<0,
assuming the valve 10 includes optional spring 45, and with forces acting in the same
direction as the closing force to close armature 28 being considered positive.
[0028] This is rewritten as:
Fca > -F1 + F2 -Fc3 + F4 + +F5 -F6 + Fs,
and as
Fca > -(A1 * P1) + (A2 *P1) - (A2*P1) + (A1 * P0) + (A3*P1) - -(A1 * P1) + (A3*P1) + Fs.
Compare this to the closing force required when there is no piston 29:
Fca > F5 + Fs;
Fca>(A3*Pl)+Fs.
In both cases, Fs may be zero if no optional spring is used.
[0029] Thus by keeping diameter D3 larger than diameter D1, the closing force
Fca is large enough to close the seat 56. As the difference between the diameters D1 and
D3 increases, the closing speed of the valve 10 upon deenergization of the coil 22 also
increases. The optional spring 45 also assists in increasing the closing speed.
[0030] Thus, the effective pressure area on which P1 is acting to bias the armature
28 to the first (unenergized) position of Fig. 3 is only the difference between the area A2
at the contact diameter D2 and the cross-sectional area of the piston Al. The diameter
D1 of the piston 29 is less than the contact diameter D2 so that this effective area on
which P1 acts is downward in Fig. 3, in effect applied to a portion of surface 33. The
addition of the piston 29 thus lessens the effective area on which pressurized fluid must
be applied to maintain the valve 10 in the closed, unenergized position, and thereby
lessens the pressure differential that must be overcome in order begin opening of the
valve 10. The force of the optional spring 45 must also be overcome in order to fully
move the valve 10 to the energized position. However, the force of the spring 45 helps to
maintain the valve in the closed position of Fig. 3, especially if the valve 10 is subjected
to high G-forces, In an alternative embodiment, instead of a spring 45, a biasing force to
help maintain the closed position may be established by providing a passage from the
intermediate chamber 42 or control gallery 68 to the opening 47 so that control pressure
P2 is maintained at the surface of the piston 29 exposed to the opening 47.
[0031] When the coil 22 is energized, flux between the pole piece 24 and
armature 28 pulls the armature 28 toward the pole piece 24, as shown in Fig. 4. The face-
to-face orientation of the armature 28 relative to the pole piece 24 subjects the armature
28 to exponentially greater magnetic force as the air gap 30 decreases. In order to move
the armature 28 to the energized (second) position of Fig. 4, the magnetic force of the coil
22 must overcome the pressure differential discussed above that biases the armature 28 to
the first position of Figure 3 as well as the force of spring 45.
[0032] Shifting the armature 28 causes the poppet 54 to open relative to the valve
seat 56, thereby providing pressure P1 from the oil intake chamber 41 to the intermediate
chamber 42. The intermediate chamber 42 is normally maintained at pressure P0 but is
increased to P1 when the poppet 54 opens the valve seat 56 and the poppet 60 closes
valve seat 62 to close off the exhaust port 70. In this embodiment, the contact diameter
D3 is greater than contact diameter D2 and greater than diameter D1. In other
embodiments, the relative sizes of diameters D2 and D3 may be different, depending on
the desired functions of the valve 10. This change in pressure from P2 to P1 increases the
hydraulic pressure supplied to the engine valve system to P1. When the pressure
provided to the engine valve system changes to P1, selected engine valves may be
deactivated by latch pins, lash adjusters or another controlled device (not shown) to
thereby deactivate selected cylinders of the engine 12.
[0033] When the coil 22 is subsequently de-energized, the forces due to the flux
are removed (i.e., the net force pulling the armature 28 toward the pole piece 24), causing
the net force Fca to drive the armature 28 to the normally closed, deenergized position of
Fig. 3. Thus, the armature 28 is configured so that the net fluid force (i.e., net downward
force acting on A3 less A1) as well as optional spring force Fs contributes to closing the
valve 10, with the chamber 42 exhausting to exhaust port 70, thereby providing relatively
quick valve actuation response time from the energized to the deenergized position.
[0034] The valve 10 is provided with an air purging and self-cleaning feature.
Specifically, the armature 28 is formed with a bypass slot 53, also referred to as a bypass
channel, to permit a limited amount of oil to move from chamber 41 to chamber 42 when
the valve 10 is closed, bypassing the seat 56. Alternatively, the bypass slot may be
provided in the body 18 adjacent the seat 56. The slot 53 also allows particles of dirt to
be expelled from chamber 41 with the oil, and thus functions as a "self-cleaning" feature
of the valve 10. Additionally, air is purged from the chamber 41 through slot 53, thus
preventing an air cushion from acting against movement of the valve 10 to the energized
position of Fig. 4 when the coil 22 is subsequently energized. This allows consistent
transitioning from the deenergized to the energized position.
[0035] When the engine 12 is off so that no fluid pressure is provided in the valve
10 and the coil 22 is deenergized, assuming that the valve 10 is installed in the engine 12
with the armature 28 above the pole piece 24 (i.e., upside down with respect to the view
shown in Figs. 3 and 4), gravity will cause the armature 28 to fall to the energized
position of Fig. 4 (although the coil is not energized). Thus, when the engine 12 is
started, pressurized oil will come up the supply gallery 64 and force any air ahead of it
out of the supply chamber 41 to the control chamber 42, past the open seat 56 as the oil
proceeds into chamber 41 and gap 30, biasing the armature 28 to the closed, deenergized
position of Fig. 3. The air is expelled from chamber 42 to exhaust port 70 as the poppet
60 unseats.
[0036] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.
CLAIMS
1. A hydraulic control valve comprising:
a solenoid body;
a selectively energizable coil;
an armature positioned adjacent the coil; the coil being energizable to
generate a magnetic force that moves the armature from a first position to a second
position;
a pole piece positioned to establish a gap between the pole piece and the
armature and having a cavity that forms an opening at the gap;
a piston extending from the armature into the cavity of the pole piece and
moving with the armature;
wherein the valve body, the armature, and the piston are configured so that
the armature is biased to seat at a valve seat in the first position by pressurized fluid; and
wherein the magnetic force required to move the armature away from the
valve seat is a function of the difference between an area of the piston and an area
defined by contact of the armature at the valve seat
2. The hydraulic control valve of claim 1, wherein the piston and pole
piece are configured so that an oil seal is formed between the piston and pole piece.
3. The hydraulic control valve of claim 1, wherein the pole piece
defines another opening opposite the opening at the gap to relieve pressure against
movement of the piston toward the pole piece.
4. The hydraulic control valve of claim 1, further comprising:
a spring positioned in the cavity between the pole piece and the piston to
bias the armature to the first position.
5. The hydraulic control valve of claim 1, wherein the valve seat is a
first seat, and further comprising:
a valve stem extending from the armature opposite the piston and movable
with the armature;
wherein the armature and the valve stem include a first poppet and a
second poppet; wherein the valve body defines a supply chamber with the first seat, a
second seat, and a control chamber between the first and second seats; wherein the first
poppet is configured to sit at the first seat and the second poppet is configured to be
spaced from the second seat in the first position to substantially prevent pressurized fluid
flow past the first seat and to exhaust fluid from the control chamber past the second seat;
wherein the first poppet is configured to be spaced from the first seat and the second
poppet is configured to sit at the second seat in the second position to permit flow of
pressurized fluid from the supply chamber to the control chamber and prevent flow from
the control chamber to an exhaust port.
6. The hydraulic control valve of claim 5, wherein the piston has a
first diameter; wherein the first poppet contacts the first seat to establish the first contact
diameter when in the first position; wherein the second poppet contacts the second seat to
establish a second contact diameter when in the second position; wherein the first
diameter is less than the first contact diameter and the first contact diameter is less than
the second contact diameter.
7. The hydraulic control valve of claim 5, in combination with an
engine; wherein the hydraulic control valve is mounted to the engine such that the
armature falls to the second position when the engine is off and the coil is not energized,
thereby moving the first poppet off of the first seat to open the supply chamber to the
control chamber, air thereby expelling from the supply chamber to the control chamber
and further expelling to the exhaust port when the armature and valve stem move to the
first position when the engine is restarted.
8. The hydraulic control valve of claim 5, wherein one of the valve
body and the first poppet form a bypass channel at the first seat, allowing air to bleed
from the supply chamber to the control chamber through the bypass channel when the
valve is in the first position.
9. A hydraulic control valve comprising:
an energizable coil; an armature; a pole piece; a piston extending from the
armature;
a valve body defining a valve seat, an exhaust seat, a supply port, a control
port, and an exhaust port;
wherein the armature includes a first poppet seated at the valve seat when
the coil is not energized and substantially preventing pressurized fluid flow from the
supply port past the valve seat to the control port; wherein the armature is shifted within
the valve body toward the pole piece by a magnetic force generated by the energized coil
to move the first poppet away from the valve seat to allow fluid flow from the supply port
to the control port; wherein the piston is configured to slide in the pole piece when the
armature moves; and wherein the valve is configured such that the magnetic force
required to move the first poppet away from the valve seat is a function of a difference
between a diameter of the piston and a first contact diameter at which the first poppet
contacts the valve seat.
10. The hydraulic control valve of claim 9, further comprising:
a valve stem assembled to the armature opposite the piston and having an
exhaust poppet that is spaced from the exhaust seat when the coil is not energized to
allow fluid flow from the control port to the exhaust port, and that is seated at the exhaust
seat to prevent fluid flow from the control port to the exhaust port when the coil is
energized.
11. The hydraulic control valve of claim 10, wherein the valve is
configured such that solenoid force required to maintain the energized position is a
function of the difference between a contact diameter of the exhaust poppet at the exhaust
seat and the piston diameter.
12. The hydraulic control valve of claim 9, further comprising:
a spring positioned between the pole piece and the piston to bias the first
poppet to seat at the valve seat when the coil is not energized.
13. The hydraulic control valve of claim 9, wherein one of the valve
body and the first poppet form a bypass channel at the first seat, allowing air to bleed
from the supply port to the control port through the bypass channel when the valve is in a
first position in which the coil is not energized.
14. A hydraulic control valve comprising:
an energizable coil, an armature, a pole piece, a piston extending from the
armature;
a valve body defining a valve seat, an exhaust valve seat, a supply port, a
control port, and an exhaust port;
wherein the armature includes a first poppet seated at the valve seat when
the coil is not energized and substantially preventing pressurized fluid flow from the
supply port past the valve seat to the control port; wherein the armature is shifted within
the valve body toward the pole piece by a magnetic force generated by the energized coil
to move the first poppet away from the valve seat to allow fluid flow from the supply port
to the control port; wherein the piston is configured to slide in the pole piece when the
armature moves; wherein the valve is configured such that a force required to move the
first poppet away from the valve seat is a function of a difference between a diameter of
the piston and a diameter at which the first poppet contacts the valve seat;
a spring positioned in the cavity between the pole piece and the piston to
bias the first poppet to seat at the valve seat when the coil is not energized;
a valve stem assembled to the armature opposite the piston and having an
exhaust poppet that is spaced from the exhaust seat when the coil is not energized to
allow fluid flow from the control port to the exhaust port, and that is seated at the exhaust
seat to prevent fluid flow from the control port to the exhaust port when the coil is
energized; and
wherein the valve is configured such that a force required to maintain the
energized position is a function of a difference between a contact diameter of the exhaust
poppet at the exhaust seat and the piston diameter.

ABSTRACT

A hydraulic control valve has a solenoid body, a selectively energizable
coil, and an armature positioned adjacent the coil. The coil is energizable to generate a
magnetic force that moves the armature from a first position to a second position. A pole
piece is positioned to establish a gap between the pole piece and the armature. The pole
piece has a cavity that opens at the gap. A piston extends from the armature into the
cavity and moves with the armature. The armature is biased to seat at a valve seat in the
first position by pressurized fluid. Magnetic force required to move the armature away
from the valve seat is a function of the difference between an area of the piston and an
area defined by contact of the armature at the valve seat.