Differential pressure delay valve

A differential pressure delay valve for vacuum controlled devices is disclosed. The valve has input, output and third chambers with a controlled flow orifice in a separating plate between the input and third chambers; a diaphragm operator with a controlled flow orifice between the input and third chambers; a stem with a seal on one end attached to and operated by the diaphragm to open or close a port in the separating plate; and, a bias spring of any predetermined level to maintain the port in a closed position is located in either the input or third chambers. The diaphragm operator opens the port to balance the pressures in the input and output chambers when the change in input pressure or vacuum both is greater than the bias force of the spring and too sudden for rapid dissipation through the fixed orifices. At pressure changes less than the bias force of the spring the valve operates as a standard delay valve.

BACKGROUND OF THE INVENTION 
This invention relates to a valve generally used to control a vacuum motor 
in response to a vacuum or pressure signal from a monitored source. More 
specifically, this invention relates to control of a vacuum operated 
idle-speed control system provided with a mechanism that responds rapidly 
to a very fast increase in vacuum from the monitored source. Delay valves 
are in wide spread use throughout the automotive industry to perform 
control functions. In the present case, a delay valve in a vacuum line may 
be connected to the idle control of an automobile engine through a 
controlling dashpot. The dashpot generally controls carburetor throttle 
opening in response to a signal from the delay valve which monitors a 
vacuum signal, such as the manifold vacuum of an internal combustion 
engine. The present delay valves have a time delay between a sensing of a 
vacuum level change in the manifold vacuum and the response or "delivery 
time" of that sensed change to the controlled element or device. 
In an automobile, the failure of the dashpot to quickly respond to a rapid 
reduction in the manifold vacuum due to a delay valve leads to an open 
throttle, higher engine revolutions per minute (rpm's) and consequently 
added gas consumption. Present delay valve arrangements prevent the idle 
speed dashpot from compensating for suddenly changing engine conditions by 
providing relatively long time delays between an engine condition change 
and a response to that change in the dashpot, which change in the dashpot 
is based on the sensed engine change. 
One method of controlling a segment of the above mentioned vacuum change is 
the avoidance of the use of a delay valve; however, this leads to erratic 
engine operating conditions and added pollution control problems. 
Alternatively, a control arrangement of bypassing a delay valve, under a 
given condition or after a fixed parameter is exceeded, is preferred. Such 
a bypass arrangement allows a delay valve to operate in the present mode 
under most conditions while overcoming the circumstance where there is a 
rapid change in the monitored condition, such as a deceleration which 
causes a rapid decrease in engine manifold vacuum from atmospheric 
pressure. These sudden changes in vacuum levels are frequently experienced 
by an automotive engine, especially in such conditions as rapid 
acceleration and rapid deceleration. 
SUMMARY OF THE INVENTION 
A differential pressure delay valve constructed in accordance with the 
invention has a body enclosure wherein a separating member of plate within 
the enclosure helps to define the input and output chambers. A diaphragm 
or pneumatic operator in the cavity partitions a third chamber from the 
input chamber. The separating member defines a port through which a stem 
extends. The stem has sealing means at one end, and is affixed to the 
diaphragm operator at its opposite end. 
An umbrella valve and a fixed orifice are mounted in the separating member 
and communicate between the input and output chambers. The stem is 
operable by the diaphragm operator and is biased by a spring to normally 
seal the centrally located port. The diaphragm operator defines a fixed 
orifice for communication between the input chamber and the third chamber. 
The monitored input control parameter is communicated to the input chamber 
by an input port and the output chamber communicates with the control 
device through an output port. Both the input and output ports are defined 
by the valve body and have protruding fittings to allow connection between 
the valve and the monitored and control elements. 
More particularly this differential pressure delay valve has as a principal 
objective to allow the rapid dissipation of a sudden change in vacuum or 
pressure differential which varies from a fixed or predetermined pressure 
or vacuum level. The pressure or vacuum differential between input and 
output chambers is allowed to balance or maintain equilibrium by the 
opening of the centrally located port. The bias of the spring mounted in 
one of the chambers determines that level at which that port, that is, the 
stem and seal, will open. The pressure or vacuum differential between the 
input chamber and the third and output chambers attains equilibrium 
thereafter through the fixed orifices of the separating member and the 
diaphragm operator.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 a pressure differential delay valve 10 is shown with a valve body 
or wall structure 12 having a side wall 14 and a bottom wall 16 where body 
12 defines an enclosure, an input port 18, and an output port 20. The 
enclosure is divided into three chambers. A separating plate or member 22 
is mounted in the body enclosure, and in cooperation with body 12 defines 
an output chamber 24. A diaphragm or pneumatic operator 26 mounted in the 
body enclosure in conjunction with body 12 defines third chamber 28. 
Diaphragm operator 26, separating plate 22 and valve body 12 define an 
input chamber 30 positioned between chambers 24 and 28 in the body 
enclosure. 
Separating plate 22 defines a centrally located port 32, which communicates 
between input chamber 30 and output chamber 24. Mounted in separating 
plate 22 are a fixed orifice 34 and an umbrella valve arrangement 36; 
orifice 34 and valve 36 communicate between input chamber 30 and output 
chamber 24. Fixed orifice 34 communicates between input chamber 30 and 
output chamber 24 to allow a controlled rate of change of pressure between 
chambers 30 and 24. Mounted in diaphragm operator 26 is a second fixed 
orifice 38 communicating between input chamber 30 and third chamber 28 and 
allowing a controlled rate of pressure change. Affixed on either side of 
diaphragm operator 26 are mounting plates 40 and 42 in chambers 28 and 30, 
respectively. Connected to mounting plate 42 is a stem 44 with a sealing 
or seal device 46 mounted on its opposite end. Stem 44 extends through 
chamber 30 and port 32, and stem 44 in its movement displaces seal 46 to 
open port 32 or to sealingly engage and close port 32. Stem 44 is operable 
by diaphragm operator 26. Stem 44, diaphragm operator 26, and seal 46 are 
shown in their port-closing position in FIG. 1. A bias spring 48, mounted 
between separating plate 22 and mounting plate 42 in chamber 30, maintains 
seal 46 in a closed position in the illustrated valve position. The bias 
force of spring 48 may be selected at any predetermined value down to two 
inches of mercury or larger. 
Port 18, which opens from input chamber 30 in sidewall 14 has a connecting 
element 50 affixed therein for communication between a vacuum source 54 
and chamber 30. Similarly, port 20 which opens from output chamber 24 in 
bottom wall 16 has a connecting element 52 affixed therein for 
communication between chamber 24 and a controlled device or element 56, 
generally a vacuum motor or dashpot. 
The differential pressure delay valve 10 is responsive to a vacuum 
condition, such as, in this case, a pressure condition below atmospheric 
pressure. The terms "input vacuum" and "output vacuum" refer to the 
condition in the input chamber 30 and the output chamber 24, respectively. 
Vacuum source 54 can be an internal combustion engine manifold vacuum or a 
vacuum pump. In the case where manifold vacuum from an automobile engine 
is used the valve will track the changing vacuum conditions such that the 
following conditions will prevail: (1) input vacuum conditions will equal 
output vacuum conditions at vacuum changes greater than the bias force of 
bias spring 48; and, (2) at differential vacuums greater than the force of 
bias spring 48, valve 10 allows input to equal output immediately and only 
allows a delay for the portion of the differential in vacuum levels less 
than the bias force of spring 48. 
In FIG. 1, delay valve 10 is shown with stem 44 urging seal 46 against 
separating plate 22, thereby sealing port 32. Diaphragm operator 26 with 
mounting plates 40 and 42 maintains seal 46 in this closed position by 
bias spring 48 at vacuum differential levels between chambers 30 and 28 
less than the bias force of spring 48. The pressure or vacuum level of 
input chamber 30 is continuously allowed to communicate at a controlled 
rate to third chamber 28 through second fixed orifice 38. 
As a vacuum as previously described is introduced to chamber 30, it can 
communicate to chambers 24 and 28 through fixed orifices 34 and 38, 
respectively. However, the rate of this pressure communication is 
relatively slow by design. The vacuum depression, that is, the pressure 
decrease from atmospheric pressure, in chamber 30 can get larger at a rate 
of increase that is greater than the rate of pressure equalization between 
chambers 28 and 30. As a result the differential between the pressure (a 
force) in chambers 30 and 28 can increase until this force is sufficient 
to overcome the predetermined bias force of bias spring 48 to open port 
32. There is also a differential pressure between chambers 30 and 24 which 
follows the pressure differential between chambers 30 and 28, but there is 
no fixed relationship between these two pressure differentials. When the 
pressure differential between chambers 30 and 28 is great enough diaphragm 
operator 26 flexes toward chamber 30, depressing stem 44 and moving 
sealing device 46 away from port 32 to allow immediate communication 
between chambers 30 and 24. This direct communication immediately balances 
the vacuum levels in chambers 30 and 24. Bias spring 48 brings valve 10 to 
the illustrated position when the differential vacuum between chambers 30 
and 28 is less than the bias force. The remaining slight differential 
between chambers 30 and, 24 and 28 is then allowed to slowly dissipate and 
balance through fixed orifices 34 and 38, respectively. 
The vacuum level in input chamber 30 is allowed to immediately communicate 
to output chamber 24 when there are sudden large changes in the vacuum 
input level. At rates of input vacuum increase in chamber 30 less than the 
rate of vacuum equalization between chambers 30 and 28 through orifice 38 
the vacuum differential between chambers 30 and 24 will only communicate 
through orifice 34. Immediate communication between chambers 30 and 24 
also occurs upon a sudden increase in pressure in the input chamber. This 
sudden pressure increase is communicated through umbrella valve 36 from 
chamber 30 through chamber 24. During a sudden pressure increase diaphragm 
operator 26 maintains its position and seals port 32 with seal 46. 
Thus the output vacuum level will not be greater than the input vacuum 
level, and for any vacuum differential between input and output above the 
bias spring 48 force, there will be an immediate balancing response by 
valve 10. The final incremental vacuum difference less than the bias 
spring force is allowed to slowly balance from chamber 30 through the 
orifices 34 and 38 to chambers 24 and 28, respectively. 
In the case of an automobile dashpot controller, the following problem is 
thereby resolved: At a false start, that is, sudden acceleration and then 
sudden deceleration, the change in vacuum level is communicated 
immediately from the manifold vacuum, through the input chamber, to the 
output chamber and thereby to the dashpot to reduce the throttle opening 
and engine rpm's. This reduction in engine rpm's results in fuel savings 
and gives the driver immediate control of the engine with a lower idle 
rate. 
FIG. 2 illustrates an alternative embodiment of a differential delay valve 
110 that is responsive to a change in pressure above atmospheric or above 
any reference pressure. Delay valve 110 is shown with a valve body 112 
with a sidewall 114 and a bottom wall 116, where valve body 112 defines an 
enclosure which is divided into three chambers. 
A separating plate 118 is mounted in the body enclosure and, in cooperation 
with body 112, defines an output chamber 120. A diaphragm operator 122 is 
mounted in the enclosure and, with valve body 112, defines a third chamber 
124. The volume between diaphragm operator 122 and separating plate 118 in 
the enclosure is an input chamber 126. Separating plate 118 defines a 
centrally located port 128 communicating between chambers 126 and 120. 
Mounted in separating plate 118 are a fixed orifice 130 and an umbrella 
valve 132 which relieves a high pressure from output chamber 120 to input 
chamber 126. Mounted in the diaphragm operator 122 is a fixed orifice 134 
communicating between input chamber 126 and third chamber 124. Mounted on 
either side of diaphragm operator 122 are mounting plates 136 and 138 in 
chambers 124 and 126, respectively. A stem 140 is affixed to mounting 
plate 138 and is operable by diaphragm 122. Affixed to or near the end of 
stem 140 in chamber 126 is a sealing device 142 operable with tube 140 and 
engageable with separating plate 118 to seal port 128 when valve 110 is in 
the position shown in FIG. 2. A bias spring 144 is positioned between 
mounting plate 136 and valve body 122 in chamber 124 to maintain sealing 
device 142 in the closed position. 
Sidewall 114 defines an input port 146 with a fitting 148 affixed therein 
to communicate between a controlling or monitored pressure source 154 and 
input chamber 126 of valve 110. Bottom wall 116 defines an output port 150 
with a fitting 152 positioned therein to communicate between a pressure 
controlled device or element 156 and output chamber 120 of valve 110. 
The closed position of valve 110 in FIG. 2 is shown wherein sealing device 
142 engages separating plate 118 to block communication between chambers 
126 and 120 through port 128. Diaphragm operator 122, stem 140 and seal 
143 are maintained in their illustrated positions to close port 128 by 
bias spring 144. A pressure imposed in chamber 126 through port 146 from a 
source 154 would dissipate to output chamber 120 through fixed orifice 
130, and to chamber 124 through fixed orifice 134. When the pressure in 
input chamber 126 is such that the pressure differential between third 
chamber 124 and input chamber 126 is greater than the bias force of spring 
140 then diaphragm operator 122 will move to open port 132 and thereby 
immediately equalize the pressure in chamber 126 and 120. Diaphragm 
operator 122 will close port 128 with seal 142 when the bias force of 
spring 144 is greater than the pressure differential between chambers 126 
and 124. The pressure differential between chambers 126 and 124 is 
dissipated at a controlled rate through fixed orifice 134. A sudden 
increase in pressure in chamber 120 above that in chamber 126 would be 
rapidly balanced through umbrella valve 132. 
Fixed orifices 34 and 38 of FIG. 1, and fixed orifices 130 and 134 of FIG. 
2 are apertures which may have a porous plug inserted therein to operate 
as a fixed orifice. In FIG. 3 a porous plug 31 is illustrated as retained 
in a fixed orifice such as orifice 34 or 38 of FIG. 1 and orifices 130 or 
134 of FIG. 2. 
Those skilled in the art will recognize that certain variations can be made 
in the illustrated embodiments. While only specific embodiments of the 
invention have been described and shown, it is apparent that various 
alterations and modifications can be made therein. It is, therefore, the 
intention in the appended claims to cover all such modifications and 
alterations as may fall within the true scope and spirit of the invention.