Patent Application
20050271518
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The present invention is directed toward pumps, and particularly toward vacuum primed pumps.
Pumps for liquids or fluids, often having non-microscopic solid particles therein, are well known in the art, and commonly use a rotary or centrifugal action to mechanically impel the fluid in the desired direction.
Typically vacuum primed pumps are positioned above the level of the liquid being pumped. In such installations, the pump will not operate properly unless there is a head of fluid from the lower liquid level into the pump itself. That is, if the fluid does not reach into the pump, the pump will merely drive air and will not create a sufficient force to draw the fluid up to the pump for the desired pumping. Therefore, such pumps are primed with fluid to ensure that there is the desired head of fluid extending into the pump so that it may operate as desired.
With many current design vacuum primed pumping systems, a capacitance electrode sensor is provided which detects the presence or absence of priming fluid at the desired level (i.e., into the pump). When it is desired to operate the pump, as typically indicated by a manual or automatic signal to turn on, the sensor first is checked to determine if there is an adequate level of priming fluid in the pump. If there is, operation of the pump is initiated and the desired pumping takes place. If the sensor does not determine that there is an adequate level of priming fluid in the pump, then a primer is initiated to draw priming fluid into the pump, with operation of the primer continuing until the sensor detects that the priming fluid has reached an adequate level, at which point operation of the pump is then initiated for the desired pumping.
In many such pumping systems, the presence of solid particles in the priming fluid has resulted in damage to the sensors, which may be abraded over time or directly interfered with by crud adhering to the sensors. As a result, the pump may either be ineffective in operating while it is incapable of pumping the desired fluid (with such operation also potentially damaging those pumps which rely upon the pumped fluid to assist in cooling the pump seal), or may be ineffective as a result of not operating, even though it would properly pump, where the sensor gives an erroneous indication that there is not sufficient priming fluid.
Moreover, even when operating correctly, such pumping systems will not operate to pump fluid as soon as such pumping is called for because the pump will not operate until sufficient priming fluid is drawn into the system first where the sensor indicates such a need. As a result, pumping may be delayed, which may be particularly undesirable where there is an urgent need for immediate pumping. Such a delay may be most significant where vacuum priming is used, such priming being relatively inexpensive but also relatively slow, particularly where priming fluid must be drawn a considerable height and/or where primary pumping demands may be infrequent such that priming fluid may drain down to such low levels between each pumping demand.
The present invention is directed toward overcoming one or more of the problems set forth above.
In one aspect of the present invention, a pumping system is provided, including a main pump for fluid, a primer for the main pump, and a main pump controller. The primer includes a vacuum source for drawing priming fluid into the pump, a priming fluid sensor adapted to substantially constantly sense the presence of priming fluid at a selected level, and a primer controller adapted to actively connect the vacuum source to draw priming fluid into the pump substantially immediately upon the sensor not sensing priming fluid at the selected level. The main pump controller is adapted to initiate operation of the main pump substantially immediately upon receiving an indication that pumping is desired.
In one form of this aspect of the invention, the priming fluid sensor is a vibratory fork liquid sensor located at the selected level.
In another form of this aspect of the invention, a valve is between the vacuum source and the priming fluid sensor, with the valve opening and closing responsive to the primer controller. In a further form, the valve opening and closing is responsive to the primer controller substantially constantly.
In yet another form of this aspect of the present invention, the vacuum source comprises a selectively operable venturi air pump. In a further form, the venturi air pump is operable by compressed air, and a second valve is between the venturi air pump and a source of the compressed air wherein the second valve opens and closes responsive to the primer controller. In another further form, a valve is between the venturi air pump and the priming fluid sensor, with the valve opening and closing responsive to the primer controller. In a still further form, a float check valve is between the venturi air pump and the valve.
In another aspect of the present invention, a method of operating a pump comprises continuously sensing for the presence of adequate priming fluid, adding priming fluid to the pump whenever the presence of priming fluid is not sensed, and initiating operation of the pump substantially immediately upon receiving an indication that pumping is desired.
In one form of this aspect of the present invention, the step of adding priming fluid creates a vacuum in a priming fluid chamber whenever priming fluid is not sensed at a selected level in the priming fluid chamber.
In another form of this aspect of the present invention, the pump is shut down if the presence of priming fluid is not sensed during pump operation.
In another aspect of the present invention, a pumping system is provided including a main pump for fluid, a primer for the main pump, and a main pump controller. The primer includes a vacuum source for drawing priming fluid into the pump, a vibratory fork liquid sensor adapted to selectively sense the presence of priming fluid at a selected level, and a primer controller adapted to actively connect the vacuum source to selectively draw priming fluid into the pump when the sensor does not sense priming fluid at the selected level. The main pump controller is adapted to initiate operation of the main pump upon receiving indications that both pumping is desired and priming fluid is sensed at the selected level.
In one form of this aspect of the present invention, a valve is between the vacuum source and the priming fluid sensor, with the valve opening and closing responsive to the primer controller. In a further form, the valve opening and closing is responsive to the primer controller substantially constantly. In an alternate further form, the valve opening and closing is also responsive to the indication that pumping is desired, whereby the valve is unresponsive to the primer controller when pumping is not desired.
In another form of this aspect of the invention, the vacuum source is a selectively operable venturi air pump. In a further form, the venturi air pump is operable by compressed air, and a second valve is between the venturi air pump and a source of the compressed air wherein the second valve opens and closes responsive to the primer controller. In another further form, a valve is between the venturi air pump and the priming fluid sensor, with the valve opening and closing responsive to the primer controller. In a still further form, a float check valve is between the venturi air pump and the valve.
A pumping system 10 according to the present invention is shown in
The pump 16 is connected to the fluid 14 by a line 20 such as a tube or pipe. The line 20 is a suction line which is connected to the bottom of the pump 16 whereby fluid 14 may be drawn up into the pump 16 for pumping from a pump outlet 24.
The pump 16 illustrated particularly in
A primer chamber 50, which may be a part of the adapter for the pump motor 38 and volute 30, is defined above the volute 30, and is used to draw priming fluid into the pump 16 as described below. A vibratory fork liquid sensor 52 is positioned in the primer chamber 50 at a suitable location whereby the sensor 52 will reliably detect the presence, or not, of a suitable level of priming fluid in the primer chamber 50. Moreover, a vibratory fork liquid sensor 52 will be significantly less susceptible to deterioration over the long expected useful life of the pumping system 10, thereby significantly improving over the prior art systems in which capacitance electrode sensors have been used.
It should be appreciated that the sensor 52 may be variously positioned relative to the pump 16, with the design requirement being that the sensor 52 be positioned so that it will be able to detect when an adequate level of primer fluid is not present for operation of the pump 16. Thus, it should be appreciated that the sensor 52′ could be alternately positioned as indicated in phantom in
As illustrated in
The vacuum may be advantageously achieved as follows. The vacuum line 54 is connected to a suitable venturi-type air pump 60, which is itself connected to a compressed air source 64. A first valve 70 is present between the compressed air source 64 and the venturi-type air pump 60 so that, when a vacuum is desired, the first valve 70 may be selectively opened to allow air to be forced through the venturi-type air pump 60 and generate a vacuum such as is well known in the art for such pump types. An air filter 74 may be advantageously provided between the compressed air source 64 and the first valve 70 to protect the valve 70 and the venturi-type air pump 60 from impurities which might prevent proper operation of either.
A second valve 80 is provided in the vacuum line 54 connected to the venturi-type air pump 60. The second valve 80 may be selectively opened to allow the vacuum created by the venturi-type air pump 60 to be drawn through the line 54 and into the primer chamber 50 as previously described. A float check valve 84 may also be advantageously provided to prevent primer fluid from being undesirably drawn up onto the venturi-type air pump 60 should the second valve 80 fail or be improperly opened for some reason. A filter 82 may also be provided to further protect the venturi-type air pump 60.
It should be appreciated that the pump 60 and the various vacuum line components (i.e., the second valve 80, the filter 82, and float check valve 84), as well as the first valve 70 may be provided separately for installation at the pump assembly, or may advantageously be provided in a single unit requiring no assembly at the installation.
It should also be understood and appreciated that the vacuum for priming the pump 16 may be generated by any suitable manner, and the present invention in its broad scope is not limited to the illustrated venturi-type air pump 60 described above. Moreover, where a venturi-type air pump 60 such as described is used, the invention is not limited to operation using a compressed air source 64 such as described, and any suitable source of air which will operate that pump 60 may be advantageously used within the scope of the present invention.
A suitable controller 90 is provided for the main pump 16 and the first and second valves 70, 80, responsive to the sensor 52 and to any signal indicating a need for the main pump 16 to operate (e.g, either an automatic signal such as from a float sensor, or a manual signal such as from the manually operable on/off switch 92 illustrated in
In a particularly advantageous form of the present invention, the sensor 52 is constantly active to sense the presence of priming fluid at an adequate level in the primer chamber 50. Whenever the sensor 52 senses such fluid, both the first and second valves 70, 80 are maintained in a shut position by the controller 90. If at any point in time the sensor 52 senses that there is not adequate priming fluid present, then the controller opens both the first and second valves 70, 80, causing a vacuum to be generated by the venturi-type air pump 60 (as a result of compressed air from the compressed air source 64 rushing through the venturi-type air pump 60), thereby creating a vacuum in vacuum line 54. The vacuum draws priming fluid through the line 20 into the pump volute 30 and primer chamber 50, until an adequate level is again detected by the sensor 52, at which point the controller 90 again shuts the first and second valves 70, 80. This operation occurs continuously so that, when a signal is received indicating a need for the main pump 16 to operate, it may be immediately turned on.
It should be understood, however, that pumping systems embodying some features of the present invention could be used with prior art modes of operation, including activating the sensor 52 to detect the presence of adequate priming fluid only when a signal is received indicating a need for the main pump 16 to operate. While the advantageous immediate pump operation as described above may not be achieved (if adequate priming fluid is not present when such a signal is received), the other advantages of such a pumping system using a vibratory fork liquid sensor 52 may still be achieved.
Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.
