Fluid handling – Systems – Dividing into parallel flow paths with recombining
Reexamination Certificate
1999-07-06
2001-05-22
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Systems
Dividing into parallel flow paths with recombining
C123S472000
Reexamination Certificate
active
06234204
ABSTRACT:
The invention relates to a flow control valve according to the preamble of claim 1.
With the known flow control valves, the flow rate is typically controlled through enlarging and reducing an orifice, such as is for instance the case with a needle valve. Such flow control valves have the advantage that the flow rate can be varied thereby in an accurate and stepless manner. However, the drawback of such a continuously controllable or analogous valves is that when a large control range is required, the accuracy of the control decreases substantially. Another drawback of continuously controllable or analogous valves is that the speed at which the flow rate can be varied is limited. In order that sufficient speed of control is nevertheless realized with continuously controllable valves, very heavy and/or sophisticated valve driving means are necessary, which render the valve costly. The above drawbacks are typical for continuously controllable valves of a large control range.
So-called two-position valves or bistable valves do not have these drawbacks. Generally, the two-position valves have in one position a maximum flow rate Q
max
and in the other position a minimum flow rate Q
min
, usually zero. To bring the valve body from one position into the other position, simple valve driving means will suffice, which only need to bring the valve body from one stable position into the other stable position. This is in contrast to the valve driving means of the continuously controllable valve which should also be capable of fixing the valve body in each intermediate position. Moreover, with bistable or two-position valves, a flow rate of any magnitude can be selected without this having an essential influence on the speed at which the valve can be opened and closed. Hence, the ‘control range’ of such a valve can be chosen to be very large, however the accuracy of the control is minimal, as the valve is open or closed.
The object of the invention is to provide a flow control valve whose flow rate can be controlled with great speed and accuracy, and which can be manufactured in an economical manner.
To this end, the flow control valve of the type mentioned in the preamble is characterized by the features of the characterizing part of claim 1.
With such a flow control valve, the advantages of the continuously controllable valve of a small control range, i.e. a high control accuracy, are combined with the advantages of the two-position valve, i.e. a large ‘control range’ with a high control speed.
The control range of the flow control valve can be rendered as large as possible with a minimum number of two-position valves if the flow control valve has the characterizing features of claim 2.
When different two-position valves of the series are each indicated by a serial number i and when the maximum flow rate of the two-position valve of the smallest maximum flow rate is indicated by Q
1
, then the maximum flow rate of the other two-position valves in the series meets the following formula:
Q
i
=2
(i−1)
*Q
1
Accordingly, the flow rate of the first 6 valves of the series is: Q
1
, 2Q
1
, 4Q
1
, 8Q
1
, 16Q
1
, 32Q
1
. Hence, the flow rate of the two-position valve increments according to a binary series, so that combining different valve positions of, for instance, six valves, enables variation in a flow control range of from 0 to 63Q
1
with a step magnitude of Q
1
.
When the flow control valve according to claim 2 also possesses the features of claim 3 and hence has a fine-control valve of which the difference between the minimum and the maximum flow rate is at least Q
1
, then the flow rate of the flow control valve can be varied continuously in a highly accurate manner in a control range which ranges from the minimum flow rate of the fine-control valve to 63Q
1
plus the maximum flow rate of the fine-control valve.
In accordance with claim 4, the minimum flow rate of the fine-control valve of the flow control valve can be zero, as a consequence of which the flow control valve can also act as a shut-off valve. In the above example, this results in a flow control valve having a control range of from 0 to 64Q
1
.
In accordance with an alternative embodiment of the flow control valve, the fine-control valve can be designed as indicated in claim 5. The control range of the fine-control valve can for instance be from 0.5Q
1
to 1.5Q
1
. This offers the advantage that the fine-control valve need not close off completely. Thus, accurate fits are avoided and mechanical wear is practically ruled out. Moroever, the system becomes less sensitive to contaminations in the fluid of which the flow rate is to be controlled. In the above example, a flow control valve having a thus designed fine-control valve would have a control range of from 0.5Q
1
to 64.5Q
1
.
REFERENCES:
patent: 3038449 (1962-06-01), Murphy et al.
patent: 4248263 (1981-02-01), Langill et al.
patent: 4768544 (1988-09-01), Beam et al.
patent: 5150690 (1992-09-01), Carter et al.
patent: 5329965 (1994-07-01), Gordon
patent: 0 420 599 (1991-04-01), None
patent: 2 163 275 (1973-07-01), None
Hepperle Stephen M.
Kinney & Lange , P.A.
LandOfFree
Flow control valve does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flow control valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flow control valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2569032