Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates to a control valve. More particularly, the
present invention
relates to a dual poppet fluid control valve which, when an abnormal situation
is encountered, the
valve moves to a locked out position which then requires a resetting operation
before the control
valve will again function.
This application is a division of commonly assigned Canadian Patent
Application
No.2,220,919 filed November 12, 1997.
BACKGROUND AND SUMMARY OF THE INVENTION
Machine tools of various types operate through a valuing system which
interacts with a
pneumatic controlled clutch and/or brake assembly. For safety reasons, the
control valves which
are used to operate these machine tools require the operator to actuate two
separate control signal
applying contacts essentially simultaneously. This requirement of simultaneous
application ensures
that the operator will not have his hand near the moving components of the
machine tool when an
operating cycle is initiated. The two control signal applying contacts can
then be connected to the
valuing system which allows compressed air to be delivered to the machine tool
to perform its
operating cycle.
Safety rules and regulations require the valuing system to be designed such
that if a
component in the valuing system malfunctions, the valuing system will not
allow additional
movement of the machine tool. In addition, the valuing system must ensure that
a new operation
cycle of the machine tool cannot be initiated after a component of the valuing
system has become
defective.
Prior art electromagnetic valuing systems which are utilized for the operation
of machine
tools meet these safety requirements through the use of a double valve
assembly. The double
valve assembly, includes two electromagnetic supply valves which are normally
closed. Each of
the supply valves is moved to an open position in response to an electrical
control signal. The two
supply valves are arranged in series with respect to the source of compressed
air. The double
valve assembly also includes two exhaust valves which are normally open. Each
exhaust valve is
closed by a respective supply valve when it is opened. It is therefore
necessary for the supply
valves to be opened simultaneously otherwise, supply air will be exhausted
from the system
through one of the exhaust valves. The opening and closing of the valve units
is monitored by
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sensing air pressures in the respective valve units and then compare these two
pressures. The
monitoring and comparing of these two pressures is accomplished by using a
single air cylinder
which is separated into two chambers by a piston. The pressure in each valve
unit is delivered to
one of the chambers. Thus, unequal pressures in the valve units will cause
movement of the
normally static piston which will then interrupt the electrical signal to one
of the valve units. This
and other external electronic monitoring arrangements are expensive and
require that electrical
signal processing equipment be designed and utilized.
The continued development of the valuing systems for machine tools has been
directed
toward more reliable, simpler and less costly valuing systems which both meet
and exceed the
safety performance requirements in force today as well as those proposed for
the future.
The present invention provides the art with a control valve system which
operates entirely
pneumatically thus eliminating the need for electrical monitoring and the
associated controls. The
control valve system includes a plurality of valves each of which open or
close during the actuation
or deactuation of the valves. The control valve system monitors the dynamic
movement of the
various valves of the system to ensure the proper functioning of the control
valve system. The
control valve system moves to a locked out position upon sensing a malfunction
and remains in
this locked out position until a resetting operation is performed. Thus, the
operation of the control
assembly is totally dynamic and the system does not rely on the monitoring of
a static member to
ensure its proper function.
Generally speaking the present invention may be considered as providing a
control valve
system comprising: a housing defining a reset port, an inlet, an outlet and an
exhaust; a first
passage extending between the inlet and the outlet; a second passage extending
between the
outlet and the exhaust; a first plurality of valves disposed within the first
passage, each of the first
plurality of valves being movable between a deactuated position where the
first passage is closed
and an actuated position where the first passage is open; a second plurality
of valves disposed
within the second passage, each of the second plurality of valves being
movable between a
deactuated position where the second passage Is open and an actuated position
where the
second passage is closed; means for maintaining one of the first plurality of
valves in the actuated
position when one other of the first plurality of valves is in the deactuated
position; and a reset
passage extending between the first passage and the reset port, each of the
first plurality of valves
being moved to the deactuated position when a pressurized fluid is supplied to
the reset port.
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Other advantages and objects of the present invention will become apparent to
those
skilled in the art from the subsequent detailed description, appended claims
and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which illustrate the best mode presently contemplated for
carrying out the
present invention:
FIG. 1 is a schematic circuit diagram of the control valve system of the
present invention
shown in a deactuated position;
FIG. 2 is a schematic illustration of the control valve shown in its
deactuated position;
FIG. 3 is a schematic circuit diagram of the control valve system of the
present invention
shown in an actuated position;
FIG. 4 is a schematic illustration of the control valve shown in its actuated
position;
FIG. 5 is a schematic circuit diagram of the control valve system of the
present invention
shown in an abnormal position;
FIG. 6 is a schematic illustration of the control valve shown in its abnormal
position;
FIG. 7 is a schematic circuit diagram of the control valve system of the
present invention
shown in a locked out position;
FIG. 8 is a schematic illustration of the control valve shown in its locked
out position; and
FIG. 9 is a schematic illustration of the valuing system in accordance with
another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in which like reference numerals designate like
or
corresponding parts throughout the several views, there is shown in FIGS. 1
and 2 a control valve
system in accordance with the present invention which is designated generally
by the reference
numeral 10. Control valve system 10 is shown as a schematic fluid circuit in
FIG. 1 and as a fluid
control valve in FIG. 2.
Referring now to FIG. 2, control valve system 10 comprises a housing 12 having
a fluid inlet
passage 14, a fluid outlet passage 16, a fluid exhaust passage 18, a first
valve bore 20, a second
valve bore 22, a first fluid reservoir 24 and a second fluid reservoir 26.
Disposed within first valve
bore 20 is a first valve member 28 and disposed within second valve bore 22 is
a second valve
member 30. Located within inlet passage 14 in a coaxial relationship with
first valve member 28
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is a third valve member 32. Also located within inlet passage 14 in a coaxial
relationship with
second valve member 30 is a fourth valve member 34. A pair of solenoid valves
36 and 38 are
attached to housing 12.
A plurality of fluid passages interconnect valve bores 20 and 22 with inlet
14, outlet 16,
exhaust 18, reservoir 24, reservoir 26, valve 36 and valve 38. A fluid passage
40 extends between
inlet passage 14 and an intermediate chamber 42 formed by bore 20. A
restrictor 44 is disposed
within passage 40 to limit the amount of fluid flow through passage 40. A
fluid passage 46 extends
between inlet passage 14 and an intermediate chamber 48 formed by bore 22. A
restrictor 50 is
disposed within passage 46 to limit the amount of fluid flow through passage
46.
A fluid passage 52 extends between chamber 42 and a lower chamber 54 formed by
bore
20. A restrictor 56 is disposed within passage 52 to limit the amount of fluid
flow through passage
52. A fluid passage 58 extends between chamber 48 and a lower chamber 60
formed by bore 22.
A restrictor 62 is disposed within passage 58 to limit the amount of fluid
flow through passage 58.
A fluid passage 64 extends between passage 52 and reservoir 24 such that
restrictor 56 is located
between chamber 42 and reservoir 24. A fluid passage 66 extends between
reservoir 24 and the
input to solenoid valve 38. A fluid passage 68 extends between passage 58 and
reservoir 26 such
that restrictor 62 is located between chamber 48 and reservoir 24. A fluid
passage 70 extends
between reservoir 26 and the input to solenoid valve 36. A passage 72 extends
between the
output of solenoid valve 36 and an upper chamber 74 formed by bore 20. A
passage 76 extends
between the output of solenoid valve 38 and an upper chamber 78 formed by bore
22.
A cross passage 80 extends between the lower portion of chamber 42 and the
upper
portion of chamber 48. A cross passage 82 extends between the lower portion of
chamber 48 and
the upper portion of chamber 42. A fluid passage 84 extends between passage 80
and outlet
passage 16. A fluid passage 86 extends between passage 82 and outlet passage
16. Outlet
passage 16 is in communication with exhaust passage 18 through two ports 88
and 90. The upper
portions of chambers 54 and 60 are in communication with atmospheric pressure
through
passages 92 and 94, respectively. A reset passage 96 extends into housing 12
and is in
communication with the lower portion of chambers 54 and 60 by communicating
with passages 52
and 58, respectively. A pair of check valves 98 and 100 are disposed between
reset passage 96
and passages 52 and 58 respectively, to prohibit fluid flow befinreen passages
52 or 58 to reset
passage 96 but allow fluid flow from reset passage 96 to one or both passages
52 and 58.
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Disposed within bore 20 is valve member 102 and disposed within bore 22 is
valve member
104. Valve member 102 comprises an upper piston 106, an intermediate piston
108 and a lower
piston 110 all of which move together as a single unit. Upper piston 106 is
disposed within
chamber 74 and includes a valve seat 112 which opens and closes port 88
located between outlet
passage 16 and exhaust passage 18. Intermediate piston 108 is disposed within
chamber 42 and
includes an annular passage 114 which fluidly connects passage 40 to passage
52 when piston
108 is seated against housing 12. Lower piston 110 is located within chamber
54 and includes a
pair of seals 116 which seal inlet passage 14 from passage 92 and seal chamber
54 from passage
92. Valve member 104 comprises a upper piston 118, an intermediate piston 120
and a lower
piston 122 all of which move together as a single unit. Upper piston 118 is
disposed within
chamber 78 and includes a valve seat 124 which opens and doses port 90 located
between outlet
passage 16 and exhaust passage 18. Intermediate piston 120 is disposed within
chamber 48 and
includes an annular passage 126 which fluidly connects passage 46 to passage
58 when piston
120 is seated against housing 12. Lower piston 122 is located within chamber
60 and includes a
pair of seals 128 which seal inlet passage 14 from passage 94 and seal chamber
60 from passage
94.
Valve member 32 is located around lower piston 110 and comprises a valve seat
130 and
a valve spring 132. Valve spring 132 biases valve seat 130 against housing 12
to prohibit fluid flow
between inlet passage 14 and chamber 42. Valve member 34 is located around
piston 122 and
comprises a valve seat 134 and a valve spring 136. Valve spring 136 biases
valve seat 134
against housing 12 to prohibit fluid flow between inlet passage 14 and chamber
48.
FIGS. 1 and 2 illustrate control valve system 10 in its deactuated position.
Pressurized fluid
from input passage 14 is biasing valve seats 130 and 134 against housing 12
dosing
communication between inlet passage 14 and both chambers 42 and 48.
Pressurized fluid is
provided to passage 40 through restrictor 44, to passage 52 through annular
passage 114 through
restrictor 56 and into chamber 54 to bias valve member 102 upward as shown in
FIG. 2 seating
piston 108 against housing 12. Pressurized fluid also flows through passage
52, through passage
64 to reservoir 24 and from reservoir 24 to the inlet of solenoid valve 38
through passage 66. In
a similar manner, pressurized fluid from input passage 14 is provided to
passage 46 through
restrictor 50 to passage 58 through annular passage 126 through restrictor 62
and into chamber
60 to bias valve member 104 upward as shown in FIG. 2 seating piston 120
against housing 12.
Pressurized fluid also flows through passage 58, through passage 68 to
reservoir 26 and from
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reservoir 26 to the inlet of solenoid valve 36 through passage 70. Outlet
passage 16 is in
communication with exhaust passage 18 due to valve seats 112 and 124 being
biased upward
opening ports 88 and 90. Intermediate chambers 42 and 48 are also open to
exhaust passage 18
through cross passages 80 and 82, respectively, through passages 84 and 86,
respectively. The
fluid pressure below piston 110 and 122 of valve members 102 and 104,
respectively, bias valve
members 102 and 104 upward maintaining control valve system 10 in the
deactuated position. The
connection between passages 40 and 52 through annular passage 114 and the
connection
between passages 46 and 58 through annular passage 126 maintain fluid pressure
within
chambers 54 and 60 and reservoirs 24 and 26.
FIGS. 3 and 4 illustrate control valve system 10 in its actuated position.
Both solenoid
valves 36 and 38 have been substantially simultaneously actuated. The
actuation of solenoid valve
36 connects passage 70 and thus reservoir 26 to passage 72. Pressurized fluid
is directed into
chamber 74 to move valve member 102 downward as shown in FIG. 4. The diameter
of piston 106
is larger than the diameter of piston 110 thus causing the load which moves
valve member 102
downward. In a similar manner, the actuation of solenoid valve 38 connects
passage 66 and thus
reservoir 24 to passage 76. Pressurized fluid is directed into chamber 78 to
move valve member
104 downward as shown in FIG. 4. The diameter of piston 118 is larger than the
diameter of piston
122 thus causing the load which moves valve member 104 downward. When valve
members 102
and 104 move downward, an annular flange 140 on piston 110 unseats valve seat
130 and an
annular flange 142 on piston 122 unseats valve 134. Pressurized fluid flows
from inlet passage
14 into the lower portion of chamber 42 through passage 80 to the upper
portion of chamber 48
and through a gap 144 between valve member 104 and housing 12 to provide
pressurized fluid
to outlet passage 16. Pressurized fluid also flows through passage 84 to
outlet passage 16. In a
similar manner, pressurized fluid flows from inlet passage 14 into the lower
portion of chamber 48
through passage 82 to the upper portion of chamber 42 and through a gap 146
between valve
member 102 and housing 12 to provide pressurized fluid to outlet passage 16.
Pressurized fluid
also flows through passage 86 to outlet passage 16. The movement of valve
members 102 and
104 downward seats valve seats 112 and 124 against housing 12 to close ports
88 and 90 to
isolate outlet passage 16 from exhaust passage 18. The fluid pressure within
reservoirs 24 and
26 will initially be reduced when valves 36 and 38 are actuated but the fluid
pressure will return to
supply pressure at inlet 14 because reservoirs 24 and 26 are still open to
inlet 14 and outlet 16 is
isolated from exhaust 18.
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FIGS. 5 and 6 illustrate control valve system 10 in an abnormal position. In
FIGS. 5
and 6, valve member 104 is located in its upward position while valve member
102 is located
in its lower position. Both solenoid valves 36 and 38 are located in their
deactuated position.
Valve body 104 is located in its upward position similar to that shown in
Flc:~. 1. Pressurized
fluid from inlet passage 14 is supplied to passage 46 through restrictor 50 to
passage 58
through annular passage 126 through restrictor 62 and into chamber 60 to bias
valve
member 104 upward as shown in FIG. 6 seating piston 120 against housing 12.
Pressurized
fluid also flows through passage 68 to reservoir 26 and from reservoir 26 to
the inlet of
solenoid valve 36 through passage 70. Outlet passage 16 is in communication
with exhaust
passage 18 due to valve seat 124 being biased upward opening port 90. Valve
body 102 is
located in its lower position which opens various passages to outlet passage
16 which,
because the position of valve body 104, is open to exhaust 18. The upper
portion of chamber
42 is open to exhaust through gap 146. Pressurized fluid from inlet passage 14
is bled to
exhaust through passage 40 and through the upper portion of chamber 42 through
gap 146,
through outlet passage 16, through port 90 to exhaust passage 18. In addition,
pressurized
fluid from inlet passage 14 will bleed to exhaust 18 by entering the lower
portion of chamber
42, flow through passage 80, through passage 84, through outlet passage 16,
through port
90 and into exhaust passage 18. Pressurized fluid in passage 52 and thus
chamber 54 is
also bled to exhaust through restrictor 56 which removes the biasing being
applied to valve
body 102. In addition, fluid pressure in reservoir 24 is bled to exhaust
through restrictor 56
removing the pressurized fluid being supplied to solenoid valve 38 through
passage 66. The
amount of time for chamber 54 and reservoir 24 to bleed to exhaust will depend
upon the
size of chamber 54, reservoir 24 and restrictor 56. With the release of
pressurized air from
chamber 74 above piston 106 and the presence of pressurized air within inlet
passage 14
acting against the bottom of valve seat 130, valve spring 132 will move valve
body 102 to an
intermediate position where valve seat 130 is seated against housing 12 but
piston 108 is
not seated against housing 12. This condition is shown in FIGS. 7 and 8.
FIGS. 7 and 8 illustrate control valve system 10 in a locked out position.
When valve
seat 130 urges valve member 102 upwards due to the biasing of valve spring
132, valve seat
130 pushes against annular flange 140 to move valve rrrember 102. Because of a
lost motion
attachment between valve seat 130 and piston 110, when valve seat 130 engages
housing 12,
piston 108 has not yet engaged housing 12. Additional movement of valve body
102 is required
to seat piston 108 against housing 12 and connect passage 40 to passage 52 and
provide
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pressurized fluid to chamber 54 and reservoir 24. Without the seating of
piston 108 to housing 12,
the upper portion of chamber 42 and thus passages 40 and 52 are open to
exhaust 18 through
gap 14f, outlet passage 16 and ports 88 and 90 and exhaust passage 18. Thus
reservoir 24 is
open to exhaust along with passage 66 and the input to solenoid valve 38.
Chamber 54 is also
open to exhaust eliminating any biasing load which would urge valve body 102
upward to seat
piston 108 against housing 12. An annular shoulder 150 located on piston 110
and open to inlet
passage 14 biases valve body 102 downward with annular flange 140 being urged
against valve
seat 130 to keep valve body 102 in its intermediate position and control valve
system 10 in its
locked out position. A similar shoulder 152 is located on piston 122.
When it is desired to move control valve system 10 from its locked out
position to its
deactuated position shown in FIG. 1, pressurized fluid is supplied to reset
passage 96. Pressurized
fluid being supplied to reset passage 96 opens check valve 98 and pressurized
fluid fills reservoir
24 and chamber 54. Restrictor 56 will limit the amount of fluid bled off to
exhaust during the
resetting procedure. Once reservoir 24 and chamber 54 are filled with
pressurized fluid, the fluid
within chamber 54 acts against piston 110 to move valve body 102 upward to
seat piston 108
against housing 12. Fluid passage 40 is again in communication with passage 52
and control valve
system 10 is again positioned in its deactuated position as shown in FIGS. 1
and 2.
While the above description of FIGS. 5 through 8 have been described with
valve body 102
being located in its intermediate and locked out position and valve body 104
being located in its
deactuated position, it is to be understood that a similar locked out position
of control valve system
10 would occur if valve body 102 were located in its deactuated condition and
valve body 104 were
located in its intermediate and locked out condition. The resetting procedure
of applying
pressurized fluid to reset passage 96 would cause the pressurized fluid to
open check valve 100
to fill reservoir 26 and chamber 60. The pressurized fluid in chamber 60 would
lift valve body 104
to seat piston 120 against housing 12 reconnecting passage 46 with passage 58.
Thus, control valve system 10 is a fully fluidically operating valve system
which has the
capability of sensing an abnormal condition and responding to this abnormal
condition by switching
to a locked out condition which then requires an individual to go through a
resetting operation
before control valve system 10 will again function.
FIG. 9 illustrates another embodiment of the present invention. In the
embodiment shown
in FIGS. 1-8, piston 108 includes annular passage 114 located in an upper
surface of piston 108
to fluidically connect passage 40 with passage 52. FIG. 9 illustrates a piston
108' which fluidically
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connects a passage 40' with a passage 52' through a passage 114' located on
the external surface
of piston 108'. In a similar manner, piston 120 of valve body 104 could be
replaced with piston
108'. Fluid passage 40' is the same as fluid passage 40 and fluid passage 52'
is the same as fluid
passage 52 with the exception that passages 40' and 52' enter chamber 42
through a vertical wall
whereas passages 40 and 52 enter chamber 42 through a horizontal wall. The
operation of the
embodiment shown in FIG. 9 is identical to that described above for FIGS. 1
through 8.
While the above detailed description describes the preferred embodiment of the
present
invention, it should be understood that the present invention is susceptible
to modification,
variation and alteration without deviating from the scope and fair meaning of
the subjoined claims.
