CONTROL SYSTEM FOR RECIPROCATING DEVICE

SYSTEME DE COMMANDE D'INVERSEUR

English Abstract

A control system for a reciprocating device. The control system includes a switching valve having a fluid supply inlet, an exhaust outlet, a restrictor on the exhaust outlet, a drive line, a valve operable to connect one of the exhaust outlet and the fluid supply inlet to the drive line and a toggle for operating the valve, the toggle being movable by motive force through an arc between a first position in which fluid flow is from the fluid supply inlet to the drive line and a second position in which fluid flow is from the drive line to the exhaust outlet, the toggle passing through a middle position where fluid flow may flow from the drive line to the exhaust outlet and from the fluid supply inlet to the drive line. A reciprocating device is provided that is operable to move in a first direction due to fluid pressure in the drive line and a second, opposed, direction due to a motive force activator when pressure in the drive line is reduced (exhausted). A trigger on the reciprocating device moves with the reciprocating device. A connector is disposed between the trigger and the toggle. The connector being operable to move the toggle into the first position when moving in the second direction and to move the toggle into the second position when moving in the first direction. The connector includes a spring arranged to transmit forces from the trigger to the toggle when the trigger is moving in the first or second direction (or both, with two springs), the spring storing energy while moving in the first or second direction to force the toggle through the middle position.

French Abstract

Un système de commande pour un dispositif à mouvement alternatif. Le système de commande comprend une soupape de commutation ayant une entrée d'alimentation en fluide, une sortie d'échappement, un restricteur sur la sortie d'échappement, une ligne d'entraînement, une soupape actionnable pour connecter l'une entre la sortie d'échappement et l'entrée d'alimentation en fluide avec la ligne d'entraînement et un levier de commutation pour actionner la soupape, le levier de commutation pouvant être déplacé par force motrice à travers un arc entre une première position dans laquelle l'écoulement de fluide est de l'entrée d'alimentation en fluide à la ligne d'entraînement et une seconde position dans laquelle l'écoulement de fluide est de la ligne d'entraînement à la sortie d'échappement, le levier de commutation passant par une position intermédiaire dans laquelle l'écoulement de fluide peut se faire de la ligne d'entraînement à la sortie d'échappement et de l'entrée d'alimentation en fluide à la ligne d'entraînement. Un dispositif à mouvement va-et-vient est prévu qui peut être actionné pour se déplacer dans une première direction en raison de la pression de fluide dans la ligne d'entraînement et une seconde direction, opposée, en raison d'une force motrice activatrice lorsque la pression dans la ligne d'entraînement est réduite (épuisée). Un déclencheur sur le dispositif à mouvement va-et-vient se déplace avec le dispositif à mouvement va-et-vient. Un connecteur est disposé entre le déclencheur et le levier de commutation. Le connecteur pouvant être actionné pour déplacer le levier de commutation dans la première position lors du déplacement dans la seconde direction et pour déplacer le levier de commutation dans la seconde position lors du déplacement dans la première direction. Le connecteur comprend un ressort agencé de manière à transmettre des efforts du déclencheur au levier de commutation lorsque le déclencheur se déplace dans la première ou la seconde direction (ou les deux, avec deux ressorts), le ressort stockant l'énergie pendant son déplacement dans la première ou la seconde direction pour forcer le levier de commutation à travers la position intermédiaire.

Claims

6

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:


1. A control system for a reciprocating device, the control system comprising:

(a) a switching valve having a fluid supply inlet, an exhaust outlet, a
restrictor on the
exhaust outlet, a drive line, a valve operable to connect one of the exhaust
outlet and the
fluid supply inlet to the drive line and a toggle for operating the valve, the
toggle being
movable by motive force through an arc between a first position in which fluid
flow is
from the fluid supply inlet to the drive line and a second position in which
fluid flow is
from the drive line to the exhaust outlet, the toggle passing through a middle
position
where fluid flow may flow from the drive line to the exhaust outlet and from
the fluid
supply inlet to the drive line;

(b) a reciprocating device that is operable to move in a first direction due
to fluid
pressure in the drive line and a second,, opposed, direction due to a motive
force activator
when pressure in the drive line is reduced;

(c) a trigger on the reciprocating device that moves with the reciprocating
device;
(d) a connector between the trigger and the toggle, the connector being
operable to
move the toggle into the first position when moving in the second direction
and to move
the toggle into the second position when moving in the first direction; and

(e) the connector including a spring arranged to transmit forces from the
trigger to the
toggle when the trigger is moving in the second direction, the spring storing
energy while
moving in the second direction to force the toggle through the middle
position.


2. The control system of claim 1 in which the connector comprises a pivoting
member, the
pivoting member having a trigger opening for receiving the trigger and a
toggle opening for
receiving the toggle, the spring being located adjacent the opening for
receiving the toggle.




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3. The control system of claim 2 in which the trigger opening is on a side of
the pivoting
member opposed to the toggle opening.


4. The control system of claim 3 in which the pivoting member has a pivot, and
the pivot is
disposed between the toggle opening and the trigger opening.


5. The control system of claim 2 in which the pivoting member is a plate and
the spring is
housed in a slot that terminates at the toggle opening.


6. The control system of claim 5 in which the spring is secured in the slot by
a slider and a
stop.


7. The control system of claim 2 in which the pivot is fastened to the toggle
valve.

8. A control system for a reciprocating device, the control system comprising:

(a) a switching valve having a fluid supply inlet, an exhaust outlet, a
restrictor on the
exhaust outlet, a drive line, a valve operable to connect one of the exhaust
outlet and the
fluid supply inlet to the drive line and a toggle for operating the valve, the
toggle being
movable by motive force through an arc between a first position in which fluid
flow is
from the drive line to the exhaust outlet, the toggle passing through a middle
position
where fluid flow may flow from the drive line to the exhaust outlet and from
the fluid
supply inlet to the drive line;

(b) a reciprocating device that is operable to move in a first direction due
to fluid
pressure in the drive line and a second, opposed, direction due to a motive
force activator
when pressure in the drive line is reduced;

(c) a trigger on the reciprocating device that moves with the reciprocating
device;




8

(d) a connector between the trigger and the toggle, the connector being
operable to
move the toggle into the first position when moving in the second direction
and to move
the toggle into the second position when moving in the first direction; and

(e) the connector including a spring arranged to transmit forces from the
trigger to the
toggle when the trigger is moving in the first direction, the spring storing
energy while
moving in the first direction to force the toggle through the middle position.


9. The control system of claim 8 in which the connector comprises a pivoting
member, the
pivoting member having a trigger opening for receiving the trigger and a
toggle opening for
receiving the toggle, the spring being located adjacent the opening for
receiving the toggle.


10. The control system of claim 9 in which the trigger opening is on a side of
the pivoting
member opposed to the toggle opening.


11. The control system of claim 10 in which the pivoting member has a pivot,
and the pivot is
disposed between the toggle opening and the trigger opening.


12. The control system of claim 9 in which the pivoting member is a plate and
the spring is
housed in a slot that terminates at the toggle opening.


13. The control system of claim 12 in which the spring is secured in the slot
by a slider and a
stop.


14. The control system of claim 9 in which the pivot is fastened to the toggle
valve.

Description

CA 02294410 2000-O1-07
TITLE OF THE INVENTION
Control System for Reciprocating Device
NAME OF INVENTOR
Arthur W. Lauder
FIELD OF THE INVENTION
This invention relates to control systems for reciprocating devices.
BACKGROUND OF THE INVENTION
Some conventional switching valves have a toggle that is operated by a trigger
on a
reciprocating unit to change the direction of movement of the reciprocating
unit. The toggle
is used to operate a valve that directs fluid flow into or away from a
diaphragm (piston or like
device) that operates the reciprocating unit. The toggle passes through a
middle position
where flow is only partially directed to the middle position. In this partial
flaw position, at
low speeds of operation, the toggle may become stuck in a flutter mode where
the
reciprocating unit oscillates over a much reduced range of motion,
insufficient to drive the
toggle into a fully switched position in either direction. The present
invention is intended to
overcome this problem with such prior art switching valves.
SUMMARY OF THE INVENTION
Therefore, according to an aspect of the invention, there is provided a
control system
for a reciprocating device. The control system includes a switching valve
having a fluid
supply inlet, an exhaust outlet, a restrictor on the exhaust outlet, a drive
line, a valve operable
2 5 to connect one of the exhaust outlet and the fluid supply inlet to the
exhaust outlet and a
toggle for operating the valve, the toggle being movable by motive force
through an arc
between a first position in which fluid flow is from the fluid supply inlet to
the drive line and a
second position in which fluid flow is from the drive line to the exhaust
outlet, the toggle
passing through a middle position where fluid flow may flow from the drive
line to the
3 0 exhaust outlet and from the fluid supply inlet to the drive line. A
reciprocating device is


CA 02294410 2000-O1-07
2
provided that is operable to move in a first direction due to fluid pressure
in the drive line and
a second, opposed, direction due to a motive force activator when pressure in
the drive line is
reduced. A trigger on the reciprocating device moves with the reciprocating
device. A
connector is disposed between the trigger and the toggle. The connector being
operable to
move the toggle into the first position when moving in the second direction
and to move the
toggle into the second position when moving in the first direction. The
connector includes a
spring or springs arranged to transmit forces from the trigger to the toggle
when the trigger is
moving in one or both of the first direction and the second direction, the
spring storing
energy while moving in the one or both of the first direction and the second
direction to
force the toggle through the middle position.
The connector preferably comprises a pivoting member, the pivoting member
having a
trigger opening for receiving the trigger and a toggle opening for receiving
the toggle, the
spring being located adjacent the opening for receiving the toggle. The
trigger opening is
preferably on a side of the pivoting member opposed to the toggle opening. The
pivot is
preferably disposed between the toggle opening and the trigger opening. The
pivoting
member is preferably a plate and the spring is housed in a slot that
terminates at the toggle
opening. The spring is preferably secured in the slot by a slider and a stop.
The pivot is
preferably fastened to the toggle valve.
These and other aspects of the invention are described in the detailed
description of
2 0 the invention and claimed in the claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described preferred embodiments of the invention, with
reference
2 5 to the drawings, by way of illustration only and not with the intention of
limiting the scope of
the invention, in which like numerals denote like elements and in which:
Fig. 1 shows a schematic of a control system for a pump according to the
invention;
Fig. 2 is a plan view of a connector for use with the control system of Fig.
I;
Fig. 3 is an enlarged view of a portion of the connector of Fig. 2;


CA 02294410 2000-O1-07
3
Fig. 4 is a side view, enlarged, of a portion of the connector of Fig. 2; and
Fig. 5 is a detailed side view of an exemplary arrangement of a connector
according
to the invention between a toggle and trigger.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In this patent document, "comprising" means "including". In addition, a
reference to
an element by the indefinite article "a" does not exclude the possibility that
more than one of
the element is present.
Referring to Fig. 1, there is shown a control system for a reciprocating
device. In this
case, the reciprocating device is a pump, although the pump components are not
shown. A
conventional switching valve 10 has a fluid supply inlet 12, an exhaust outlet
14, a restrictor
16 on the exhaust outlet 14, a drive line 18, a valve 20 operable to connect
one of the fluid
supply inlet 12 and the exhaust outlet 14 to the drive line 18 and a toggle 22
for operating the
valve 20. All of these parts are conventional and available in numerous valve
switches. As is
common in these devices, the toggle 22 is movable by motive force through an
arc between a
first position 24 in which fluid flow is from the fluid supply inlet 12 to the
drive line 18 and a
second position 26 in which fluid flow is from the drive line 18 to the
exhaust outlet 14. The
toggle 22 passes through a middle position where both the exhaust outlet 14
and supply inlet
12 are open to fluid communciation with the drive line 18.
2 0 The switching valve 10 is used to control a reciprocating device 30. The
reciprocating
device 30 includes a diaphragm housing 32, a diaphragm 34, a diaphragm rod 36,
a motive
force activator such as a return spring 38, a trigger block 40 on the
diaphragm rod 36 and a
trigger 42 attached to the trigger block 40 at a point on the diaphragm rod 36
away from the
diaphragm 34. The trigger 42 is thus arranged to move with the reciprocating
rod 36. The
2 5 reciprocating device is conventional, and is operable to move in a first
direction 44 due to
fluid pressure in the drive line 18 and a second, opposed, direction 46 due to
the motive force
activator 46 when pressure in the drive line 18 is reduced (that is,
exhausted).
A connector 50 is provided between the trigger 42 and the toggle 22. An
example of
a connector 50 is shown in Fig. 1, although a preferred design is shown in
Figs. 2-S. The


CA 02294410 2000-O1-07
4
connector 50 is operable to move the toggle 22 into the first position 24 when
moving in the
second direction 46 and to move the toggle into the second position 26 when
moving in the
first direction 44. The connector 50 includes a spring 52 (shown symbolically
in Fig. 1)
arranged to transmit forces from the trigger 42 to the toggle 22 when the
trigger 42 is
moving in the second direction 46. The spring 52 stores energy while moving in
the second
direction 46 to force the toggle 22 through the middle position.
As shown in Figs. 2-S, the connector 50 is preferably formed of a pivoting
plate 54
that pivots about a carriage bolt 56. The carriage bolt 56 is conveniently
secured to the
switching valve 10 via a cover plate 58. A spacer 60 separates the pivoting
plate 54 and
cover plate 58. The pivoting plate 54 is conveniently held on the carriage
bolt 56 by a spring
62, nut 64 and washer 66.
The pivoting plate 54 has a trigger opening 68, preferably a slot as shown,
for
receiving the trigger 22 and a toggle opening 70 for receiving the toggle 42.
The spring 52 is
located adjacent the opening 70 for receiving the toggle 42. The trigger
opening 68 is
preferably on a side of the pivoting plate 54 opposed to the toggle opening 70
as shown in
Fig. 2, with the carriage bolt 56 disposed between the toggle opening 70 and
the trigger
opening 68. The spring 52 is preferably housed in a slot 72 that terminates at
the toggle
opening 70. The spring 52 is secured in the slot 72 by a cylindrical slider 74
and a stop 76,
which may be welded to the plate 54.
2 0 In operation, the switch 10 is manually operated to commence flow of
fluid, for
example air from a conventional pneumatic supply, from the fluid supply inlet
12 to the drive
line 18. The rate of fluid flow into the drive line 18 is governed by the
pressure in the fluid
supply. As fluid enters the diaphragm housing 32, the diaphragm drives the rod
36 in the first
direction 44. Trigger 42 engages connector SO (plate 54), which in turn
engages toggle 22
2 5 and forces it into the second position 26. In the second position, fluid
in the drive line 18 is
exhausted through the exhaust outlet that is controlled by the exhaust
restrictor 16. The
return spring 38 urges the rod 36 in the second direction 46, and the trigger
42 engages the
connector 50 (plate 54), which presses on the spring 52 to drive the toggle 42
towards the
first position. At the beginning of movement in the second direction, energy
is stored in the


CA 02294410 2000-O1-07
spring 52. The amount of energy stored in the spring 52 is determined by the
spring constant
and the length of compression of the spring 52 before the spring 52 stops
compressing upon
the toggle 42 reaching the stop 76. The stop 76 is shown schematically in Fig.
I as element
51. If the rate of movement is low (relatively low rate of exhaust), the
trigger 42 begins to
5 find itself trapped between oscillating flow in the drive line 18 and the
force of the return
spring 38. The spring 52 then releases its stored energy and drives the toggle
22 into the first
position. Fluid then flows from the supply inlet 12 to the drive line 18 and
the cycle begins
again and repeats until the fluid pressure is turned off. The choice of the
strength of spring 52
is readily determined.
The spring 52 may also be located in an equivalent slot at the trigger side 53
of the
plate 54. The device may also be arranged to operate in either or both
directions of
movement of the rod 36, by placing the toggle slot 70 with the spring 52 (or
an additional
slot 70 and spring S2) on the opposite side of the plate 54, at the location
illustrated
schematically in Fig. I by numeral 55. In this case, usefizl for the situation
when the rod 36
also moves slowly in the first direction, the spring 52 transmits forces from
the trigger 42 to
the toggle 22 when the trigger 42 is moving in the first direction 44 (outward
from the
diaphragm), and thus the spring 52 in this instance stores energy while moving
in the first
direction to force the toggle 22 through the middle position. Likewise, a
spring could be
provided on the other side of the trigger.
2 0 Immaterial modifications may be made to the invention described here
without
departing from the essence of the invention. As for example, various
configurations of spring
and slot may be used in a plate or similar member. Also, the trigger block may
be formed as a
ring, or other suitable device for holding the trigger.

Representative Drawing