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Патент USA US3089018

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May 7, 1963
F. w. sHlRl-:Y
SNAP-ACTING SWITCH CONTACT ACTUATING MEANS
FOR COMPRESSOR GOVERNOR
3,089,008
Filed July 7, 1960
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INVENTOR.
FRANK W. SHIREY
BY
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Patented May 7, 1963
1
2
3,089,603
pressor system including an enlarged sectionalized View
of the fluid pressure operated motor control switch device
SNAP-ACTING SWHTCH CÜNTACT ACTU/111W@
MEANS FÜR CÜMPRESSÜR QÜVERNQR
Frank W. Shirey, Irwin, Pa., assigner to Westinghouse
Air Brake Company, Wilmerding, Pa., a corporation
o1 Pennsylvania
Filed July 7, 1966, Ser. No. 41,335
6 Claims. (Cl. 20th-82)
embodying the invention.
FIG. 2 is a fragmental section View of a limiting pin
and groove arrangement used in the operating piston of
the switch device.
Description
Referring to FIG. 1 of the drawing, the fluid com
This invention relates to electric circuit control switch 10 pressor motor control apparatus includes a ñuid pressure
operated motor control switch device, hereinafter referred
to as the switch device 1, utilized in cooperation with »a
operated control switch of the snap-acting type for inter
standard compressor governor 2, to open or close the
rupting with a minimum of arcing a circuit, such as that
apparatus and more particularly to a iiuid pressure
for an electric motor driving a fluid compressor.
ln present day motor-driven fluid compressors, motor
armature circuit of a direct current motor 3 used for
driving a compressor 4 to charge a reservoir 5 with fluid
control apparatus is commonly provided in which the
under pressure as controlled by the governor 2.
motor is started and stopped by a fluid pressure operated
electric control switch operative responsively to iluid
The
of D_C. voltage represented by `a battery 6, a negative
operates responsively to variations of the stored reservoir
terminal screw 9 is connected to a movable main contact
armature circuit of the motor 3 includes a suitable source
wire 7, and a positive wire 8 connected to terminal screw
pressure supplied under the control of .a conventional com
pressor governor, such `as the well-known Westinghouse 20 9 and terminal cap nut 10, respectively, on the switch
device 1 as shown partly dotted in the drawing. The
Air Brake Company Type “S” governor. The governor
pressure between maximum and minimum pressures of
any desired range. The tluid pressure operated control
switch comprises in part a switch operating piston operable
to a switch-opening position when a piston chamber on
one side thereof is supplied with fluid under pressure from
11 by way of jumper wire 12 and terminal cap nut 13, and
the terminal cap nut lll -is connected to a stationary main
contact 14, the opening and closing of said main contacts
breaking or completing the `armature circuit respectively,
as hereinafter explained. A manually operated switch 15
is connected in the postive wire 8 for connecting or dis
connecting
the armature circuit when the apparatus is
open the motor circuit and thereby stop the motor `and the
compressor driven thereby. When tiuid pressure in the 30 to be put in service or taken out of service, respectively.
The compressor governor 2 shown in outline is of the
reservoir reduces to a predetermined pressure, the usual
W.A.B. Co. Type “5,” similar to that disclosed in U.S.
high pressure valve of the governor is seated, and the
Patent 1,615,365 (assigned to the assignee of this appli
ñuid under pressure acting on the switch operating piston
cation) with a single control passage connection between
in a piston chamber is vented via the governor. The
switch operating piston is spring biased to restore the 35 the governor and the switch device. An automatic drain
valve 16 is connected to said control passage at the switch
switch contact members to their closed position, thereby
device to empty moisture from the device as necessary.
starting the compressor motor and continuing operation
The switch device 1 comprises the usual components in
of the compressor until the fluid pressure has built up
cluding the aforementioned stationary main contact 14
in the reservoir, at which time the governor operates in
and movable main contact 11 mounted on the -free end of
the governor, to cause the switch contact members to
a well-known manner to supply ñuid under pressure to
the aforementioned piston chamber to `act on the one side
of the piston to cause the switch contact members to
move to their open position as above mentioned.
With such apparatus, it has sometimes occurred that
dirt, etc., in the high pressure valve chamber of the gover
nor causes improper opening of the high pressure valve
such that the fluid pressure is delivered to the piston cham
a contact arm 17 which is pivotally mounted `on a pin 18,
said pin 1S being secured to the switch .body 19, and an
operating piston Ztl movable to different positions within
`a bore 21 responsively to a supply of ñuid under pressure
thereto to operate cooperatively with a piston latch 22
to pivot the contact arm 17 and cause the main contacts
11 and 14 to be opened or closed.
The main contacts 11 and 1/5 are ofthe replaceable type
ber of the control switch at a reduced rate to cause slow
so as to be renewed when badly burned or pitted by arcing
opening of the contact members thereof. Another pos
therebetween. The movable main contact 11 is fastened
sible effect of dirt in the high pressure valve is improper 50 to a pivotable Contact body 23 of insulating material by
seating of the high pressure valve, resulting in leakage of
lluid under pressure past the said valve to the piston cham
ber of the control switch to cause a slow undesired fluid
pressure build~up therein to in turn cause `a slow undesired
opening of the switch contact members. The slow move
ment of the control piston caused `by the improper seat
ing or opening of the high pressure valve of the governor,
as just described, results in slow opening of the switch
contact members and excessive arcing and burning of the
main contacts to render them faulty and unable to com
plete the compressor motor supply circuitry when fluid
pressure in the reservoir is low.
According to the present invention, there is provided a
new `and improved switch apparatus having a snap »action
control of the switch contact members which produces a
complete instantaneous breaking or opening of the main
contacts upon establishment of a predetermined fluid pres
sure in the switch piston cham-ber acting on the switch
control piston.
1n the accompanying drawing,
FIG. l is a diagrammatic view of a common lluid com
the terminal cap nut 13 and a terminal 24 molded in the
body 23, said movable main contact 11 being biased to
ward the stationary main contact 14 by a contact insuring
spring 2S, wherein the contact body 23 is given limited
pivotal movement such that the contact insuring spring 25
insures a solid engagement between the two main contacts
11 and 14 when said contacts are closed. The stationary
main contact #14 is secured by the terminal cap nut 161 to
60 a terminal 26 molded in an insulating block 27. The
insulating block 2'7 is of a molded glass-tilled polyester
or similar insulating material and is secured to the switch
body 19 by suitable means such as bolts 28 in a manner
to electrically insulate the main contact 14- from the switch
body 19.
Above and adjacent to the main contacts 11 and 14 is
a pair of outwardly extending arcing contacts or arcing
horns 29 and 30 for “drawing out” the arc resultant when
the main contacts 11 and 1d are separated. The arcing
70 horns 29 and 36 are of the usual type used in conven
tional switches with respective outer extremities thereof
attached by suitable terminal screws 31 and 32 to jumper
3,089,008
3
4
wires 33 and 34 connected to the respective main contacts
contact arm 17 to be pivoted about pin 18 to its closed
14 and 11. Surrounding the main contacts and arcing
position with the movable main contact 11 engaging the
horns is a U-shaped arc chute 35 of a flame resistant
stationary main contact 14.
To initially start the compressor, the switch 15 is closed
to complete the armature circuit for the motor 3, said
insulating material with the usual appropriate arc diffuser
and arc choppers 35a interposed between the sides of said
yoke so as to assist in breaking up any arc between the
main contacts and between the arcing horns. The struc
circuit being traced from the positive terminal of the
battery 6 via the switch 15, positive wire 8, terminal 25,
tural and operational details of the arc chute and compo
stationary main contact 14, movable main contact 11
nents not being pertinent to this invention, a full descrip
tion thereof herein is deemed unnecessary. A detailed
description may be had by reference to my copending
engaging the stationary main contact 14, jumper wire 12,
application Serial No. 23,843, filed April 2l, 1960, now
abandoned, and assigned to the assignee of the present
invention.
The switch operating piston 2d is located in the lower
part of the Switch device 1 within a cylindrical bore 21,
preferably having a bushing or liner, in the switch body
)t9 with a hollow piston stem -36 extending into a bore 37
coaxial to and of a diameter smaller than bore 21.
The
piston Ztl is slidably positioned within bore 21 in a manner
to form a piston chamber 3S at one side of the face of said
to the terminal screw 9, and negative wire 7 to the motor
armature and back to the negative side of the battery 6,
thereby starting the motor 3` and compressor 4 in op
eration;
"
Being that there is no pressure in the reservoir 5, the
high'pressure valve (not shown) of the governor 2 re
mains closed to permit a build-up of fluid under pressure
in said reservoir. lt is in this period when the com
pressor is operating to build up the fluid pressure in the
reservoir that any leakage past the governor high pressure
20 valve would cause undesired build-up of pressure in the
piston chamber 38 of prior switch devices to effect an un
piston (the left side as shown in the drawing). The other
side has the hollow piston stern 36 extending into the
desired partial opening of the main contacts 11 and 14.
The partial opening of the main contacts results in arcing
bore 37 to form a spring chamber 39 for housing a piston
spring
between said piston 2t? and a washer 41 seated
to eventually render the main contacts ineffective to prop
on a circular lip 42 at the inner end (right end) of said
bore for biasing saidfpiston toward the chamber 38. An
erly engage to complete the motor armature circuit. In
the apparatus shown herein, fluid leakage past the high
therebetween with consequent burning and pitting thereof
O-ring 43 encircles the piston 2d in a groove
to main
pressure valve of the governor 2 ñows via a pipe 59, pas
tain a seal on the wall of bore 21 between the piston
sage 60, passage 61, volume 62 and port i63 to the piston
chamber 38 and the spring chamber 39.
30 chamber 38 where the slow build-up of Ipressure therein
The hollow piston stem 36 houses a contact operating
causes the piston 20 to move slowly to the right to com
rod `45 slidably «fitted within a concentric bore 46 in said
press the spring 40 and the trigger spring 47, but does not
stem 36 and a trigger spring 47 positioned between the
open the main contacts 1‘1 and 14 due to the piston latch
end of said concentric bore 46 and the closed end of a
22 being latched over the washer 37 on the circular lip
spring receiving bore 48 in said contact operating rod 45 35 42, thereby preventing burning of the main contacts 11 and
in a manner to bias said contact operating rod 45 in a
direction out of said concentric bore 46 to the right as
age is suñicient to build up the pressure in the piston
shown in the drawing.> A limiting pin 49 is inserted in
chamber 38 to a predetermined pressure, the main con
14 with premature slight openings thereof. If the leak
said contact operating rod 45 and extends radially there
tacts will be opened as hereinafter described.
through into a groove 50, as shown in FIG. 2, in the wall 40
When the tluid pressure in the reservoir 5 and con
of said concentric bore 46 to limit Lthe movement of said
contact operating rod 45 to the right in an outward direc
tion relative to said concentric bore 46.
The-right-hand or inner end of the contact operating
rod 45 is slotted or clevised to receive in the slotted por
nected governor 2 builds up to a predetermined pressure
(regulated as desired by the usual appropriate adjustment
of governor settings), the governor high pressure valve
snaps open in a -well-known manner to permit a sudden
surge of high pressure to the pipe 59 and thence to the
tion thereof the piston latch 22, both the operating rod 45 piston chamber 38. The sudden surge of ñuid pressure
45 and piston latch 22 being pivotally secured by a pin 51
rapidly builds up to a predetermined pressure necessary
to the contact arm 17 in a recess in said contact arm.
to overcome the biasing forces of spring 40, causing the
The surface of the slotted portion of the contact operating
piston 29 to move to the right in the bore Z1 to engage
rod 45 is sloped or tapered in a manner to engage the
corresponding sloped inner edge of the piston latch when 50 the piston latch 22 which is held stationary by the lip
52 on washer 41, thereby resulting in compressing the
said piston latch is uncooked as hereinafter explained.
spring
40 and at the same time compressing the trigger
The outer end of the piston latch extends into bore 37
spring 47. Simultaneously with the compression of the
and is constructed with a lip S2 to latch in a cocked posi
trigger spring 47, the beveled surface 54 on the outer end
tion over the washer 41 on the circular lip 42 of lthe inner
end of bore 37 in response to the biasing forces of a 55 of piston stem 36 engages and moves along the angular
spring 53. A spring 53 is interposed between the inner
edge of the piston latch and the tapered surface in the
surface 55 on the piston latch 22 thereby moving the-lip
is moved to the right, thereby unlatching or uncocking the
piston latch as hereinafter described.
with tapered surface of the `Contact operating rod 45,
52 inwardly on the washer 41. When the fluid pressure
in the piston chamber 38 attains a predetermined degree
slotted portion of the contact operating rod 45 in a manner
(determined by the biasing force of spring 40), the piston
to tend to maintain the two surfaces apart in a cocked
position. An annular beveled surface 54 on the outer end 60 2li and the piston stem 36 move sufficiently to the right
to cause the beveled surface 54 thereof to move the piston
of the piston stern 36engages an angular surface 55 on
latch
22 completely off the Washer 41 into engagement
the outer or free end of the piston latch 22 when Ithe piston
Operation
thereby uncocking the piston latch and permitting the
65
When the compressor is initially started with the sys
tern not being charged with ñuid under pressure, the piston
chamber 3S is void of fluid under pressure, and therefore
the operating piston 2d' is initially in the extreme left 70
compressed trigger spring 47 to sharply snap the contact
operating rod `45 and the piston latch 22 to the right, mov
ing the contact arm 17 rapidly in a clockwise movement
about pin 18 to open the main contacts 11 and 14 in a
very rapid motion to limit the arcing therebetween. The
clockwise movement of contact arm 17 is limited to a
hand position in which it is shown with a stop disc 56 on
the piston engaging a stop disc 57 on a piston chamber
cover 58. With the piston 2t) in the extreme left-hand
sutiicient degree by the movement of the pin 49 into en
gagement with the right side of the groove 50 in the
piston stem 36.
position, the force of spring 4t! acting through the medium
From the above description it can be seen that there
can be no partial slow opening of the main contacts 11
ofpiston 26 and contact operating rod 45 causes the
3,089,008
5
and 14 due to leakage of iluid in the piston chamber as
has been the case in previous switch devices, the only
b
piston operates the latch means to unlock the movable
switch contact member for operative movement out of its
type of opening being a fast complete snap opening when
contact-closing position only after movement of said pis
the fluid pressure in the piston chamber 3S is sufiicient to
move the piston 2t) and piston stem 36 to the right far
enough to unlatch or uncock the piston latch 22 to respond
ton a predetermined amount responsively to fluid pres
sure build-up in said chamber.
3. An electric circuit controlling switch device com
to the trigger spring 4'7.
prising a stationary switch contact member, a movable
With the main contacts 11 and 14 open, the circuit
switch contact member operable from a circuit-opening
energizing the compressor motor 3 is interrupted, thereby
position out of engagement with said stationary switch
stopping the compressor 4 until the pressure of fluid in
contact member into a circuit-closing position engaging
the reservoir 5 is normally ‘depleted through usage to a
said stationary switch contact member and reversely, cas
predetermined low pressure at which time the governor
ing means having a chamber therein to which ñuid under
2 operates in its usual manner to position the governor
pressure may be supplied, a piston subjectable to the fluid
high pressure valve to vent the piston chamber 38 to at
pressure in said chamber and movable responsively to
mosphere lto permit the spring 40 to return the piston 20
supply of ñuid under pressure thereto and release of Huid
to the left-hand position with the stop 56 engaging the
under pressure therefrom to effect operation of said mov
stop 57. As the piston 20 is returned to the left-hand
able contact member from its circuit-closing position to
position as shown, the right-hand end of groove 50 shown
its circuit-opening position and vice versa respectively,
in FIG. 2 in the piston stem 36 which is now in engage
latch means for locking said movable switch Contact mem
ment with the pin 49, causes the contact operating rod 45 20 ber in its circuit closing position, lost motion means con
to move to the left, and thereby simultaneously moves
necting said piston and said movable switch contact mem
the piston latch 22 to the left where the spring 53
ber, and cooperative cam means on said piston and said
latches lip 52 on the washer 41. The «contact arm 17 is
latch means whereby said piston operates the latch means
thus also returned in a counterclockwise direction to a
to unlock the movable switch contact member for opera
position in which the main contacts 11 Iand 14 are re 25 tive movement out of its contact-closing position only
closed. When the main contacts 11 and 14 are reclosed,
after the movement of said piston a predetermined
the circuit for starting the motor 3 is again complete to
amount to an unlocking position responsively to fluid
start the compressor and thereby cause the reseating of the
pressure
build-up in Said chamber.
governor high pressure valve to permit normal operation
4. An electric circuit controlling switch device as
of the compressor.
30 claimed in claim 3, further characterized by spring means
Having now described the invention, what I claim as
that is compressed by movement of said piston to a posi
new and desire to secure by Letters Patent, is:
tion for causing said cam means to unlock said latch
1. An electric circuit controlling switch device com
means and eiïective while so compressed upon such un
prising a stationary switch contact member, a movable
switch contact member operable from a circuit-opening 35 locking of said latch means for operating the movable
switch contact member to its circuit-opening position with
position out of engagement with said stationary switch
a rapid movement.
contact member into a circuit-closing position engaging
5. An electric circuit controlling switch device as
said stationary switch contact member and reversely, cas
claimed in claim 3, further characterized by spring means
ing means having a chamber therein to which fluid under
pressure may be supplied, a piston subjectable to the 40 interposed between said casing means and said piston to
yieldingly resist movement of said piston to said unlock
iluid pressure in said chamber and movable responsively to
ing position and effective to restore said piston and said
supply of fluid under pressure thereto and release of Huid
movable switch contact member to said circuit-closing
under pressure therefrom to eiîect operation of said mova
position responsively to venting of iluid under pressure
ble cont-act member from its circuit-closing position to
its circuit-opening position and vice versa respectively, and 45 from said chamber.
6. An electric circuit controlling switch device as
means operatively connecting said piston to said movable
claimed in claim 3 further characterized by trigger spring
switch contact member to prevent movement of said
means that is compressed by movement of said piston to
movable switch contact member vfrom its circuit-closing
a position for causing said cam means to unlock said
position to its circuit-opening position until after said
piston has moved a predetermined amount responsively to 50 latch means and eiîective while so compresesd upon such
unlocking of said latch means for operating the movable
a build-up of ñui‘d pressure in said chamber.
switch contact member to its circuit-opening position
2. An electric circuit controlling switch device com
with a rapid movement, and other spring means inter
prising a stationary switch contact member, a movable
posed between said casing means and said piston to yield
switch contact member operable from a circuit-opening
position out of engagement with said stationary switch 55 ingly resist movement of said piston to said unlocking
position and effective to restore said piston and said mov
contact member into a circuit-closing position engaging
able switch contact member to said circuit-closing posi
said stationary switch contact member and reversely, cas
tion responsively to venting of iluid under pressure from
ing means having a chamber therein to which ñuid un
said chamber.
der pressure may be supplied, a piston subjectable to the
fluid pressure in said chamber and movable responsively
References Cited in the ñle of this patent
to supply of fluid under pressure thereto and release of
UNITED STATES PATENTS
ñuid under pressure therefrom to eiîect operation of said
movable contact member from its circuit-closing position
2,238,567
Prince ______________ „_ Apr. 15, 1941
to its circuit-opening position and vice versa respectively,
2,730,588
Kelle ________________ __ Jan. 10, 1956
latch means for locking said movable switch contact mem 65 2,730,589
Perry et al. __________ -_ Jan. 10, 1956
ber in its circuit closing position, and cooperative cam
means on said _piston and said latch means whereby said
2,775,711
Kommer ____________ _.. Dec. 25, 1956
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