METHOD AND APPARATUS FOR CONTROLLING A RELAY PUMPING SETUP

FIELD OF THE INVENTION

The invention relates to pumping machines. More precisely, the invention pertains to a method and apparatus for controlling a relay pumping setup.

BACKGROUND OF THE INVENTION

In fighting fires, it is common practice, when water is not readily available, to either truck water in, provide aerial drops via aircraft or move water over long distances through varying terrains/elevations to get water to the fire. The first two options are quite costly. Agencies therefore choose to opt for the third option which is less expensive but has its own associated problems. Moving water over long distances requires pumps that can produce higher pressures. This is important because water is not always readily available. At times, water may. have to be pumped thousands of feet through varying terrains and elevations. However, moving water over long distances and varying terrains induces pressure losses, due in part to friction and static head.

Pressure loss is caused, in part, by increases in elevation, also referred to as static head loss. Typically, for every foot of elevation, there is a loss of approximately 0.5 pounds per square inch (psi). Static head is the pressure loss due to the difference in elevation between the pump discharge outlet and the nozzle at the end of the hose. For example, if a pump produces 100 psi and an elevation difference of 100 feet exists between the pump and the nozzle, only 50 psi is available at the nozzle. Friction loss, on the other hand, is a loss of pressure due to friction between the flow of water and the hose. Friction loss increases as the flow in a hose increases. While higher-pressure pumps may be used in order to overcome pressure and friction losses, it will be appreciated that hose pressure ratings will limit the amount of pressure that can be used.

Presently operators use many different methods for delivering water over long distances.

One method uses tandem pumping wherein at least two pumps are connected in series such that one pump pumps water into the suction of the next pump downstream and so on. One problem with this method is that if any pump in the series fails or if a hose ruptures then the entire water delivery system will fail to deliver water to the fire until all pumps/broken hoses are repaired and are up and running. The tandem setup is analogous to a chain being as strong as its weakest link. In the case of a fire, the failure of the tandem setup will result in the water delivery to the fireline being interrupted, which is a major disadvantage.

A second method uses relay pumping. In this method a first given pump pumps water into a relay reservoir and a second given pump drafts from the relay reservoir. A benefit of this type of setup is that the distance between the pumps can be greater than that of the tandem setup thus requiring fewer pumps. Another benefit of relay pumping is that if an upstream pump fails or if a hose breaks and the relay reservoir downstream is full of water, the pump drafting from the respective downstream reservoir can continue working and delivering water to the fire-line while an operator rectifies the problem upstream. This method creates a buffer in the event of a failure of an upstream pump and/or an upstream hose.

Unfortunately, a disadvantage of the relay pumping method is that if a downstream pump drafting from a relay reservoir consumes more water than what the upstream pump can furnish, the downstream pump ends up choking (running dry), i.e. there is no water to pump for the downstream pump. The result is that no water is delivered to the fire-line, and the pump may be damaged as well.

Another disadvantage of the relay pumping method is that if an upstream pump furnishes more water than the downstream pump can draft from the relay reservoir, then the relay reservoir connected to the downstream pump will

overflow, wasting valuable water, wasting fuel to keep the upstream pump running needlessly and causing unnecessary wear and tear on the upstream pump.

Unfortunately, a problem associated with relay pumping is that if the upstream pump and the downstream relay reservoir are far apart, it may be difficult or next to impossible for a single operator to control both pumps simultaneously. This is especially the case in mountainous terrain.

Further, the operator may need to check the hose as well as the relay reservoir and spend tremendous efforts to monitor the overall operation, which renders the operation very cumbersome and costly.

There is a need for a method and apparatus that will overcome at least one of the above-identified drawbacks.

Features of the invention will be apparent from review of the disclosure, drawings and description of the invention below.

BRIEF SUMMARY

According to one aspect of the invention, there is provided a controller for controlling a relay pumping setup comprising an upstream pumping unit for pumping a liquid into a relay reservoir and a downstream pumping unit for pumping from the relay reservoir to a given location, the controller comprising a relay reservoir liquid level indication interface for receiving a liquid level indication signal indicative of a liquid level in the relay reservoir, an upstream pumping unit interface communicating with the upstream pumping unit, a downstream pumping unit interface communicating with the downstream pumping unit and a processing unit for receiving the liquid level indication signal and for providing a control signal to at least one of the upstream pumping unit interface and the downstream pumping unit interface according to the liquid level indication signal. According to a further aspect of the invention, there is provided a method for controlling a relay pumping setup comprising an upstream pumping unit for

pumping a liquid into a relay reservoir and a downstream pumping unit for pumping from the relay reservoir to a given location, the method comprising receiving a relay reservoir liquid level indication indicative of a liquid level in said relay reservoir and providing a control signal to at least one of the upstream pumping unit and the downstream pumping unit depending on the received relay reservoir liquid level indication.

According to another aspect of the invention, there is provided a relay pump controller comprising a relay reservoir liquid level sensor interface which receives a liquid level indication signal indicative of a liquid level in an associated relay reservoir, an upstream pumping unit interface which transmits to an upstream pumping unit an upstream control signal, a downstream pumping unit interface which receives a downstream control signal, a pumping unit interface for controlling an associated relay pumping unit and a processing unit which, responsive to the received liquid level indication signal and the downstream control signal, controls the associated pumping unit and transmits the upstream control signal. An upstream pump is intended to mean a pump filling a relay reservoir.

A downstream pump is intended to mean a pump drafting from a relay reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be readily understood, embodiments of the invention are illustrated by way of example in the accompanying drawings. Figure 1 is a schematic showing a prior art relay pumping setup; the relay pumping setup comprises an upstream pumping unit, a relay reservoir and a downstream pumping unit; Figure 2a is a block diagram of a controller for controlling a relay pumping setup according to one embodiment; the controller comprises a liquid level sensor interface, a processing unit, a pumping unit interface and an upstream pumping unit interface;

Figure 2b is a block diagram of a controller for controlling a relay pumping setup according to another embodiment; the controller comprises a liquid level sensor interface, a processing unit, a pumping unit interface and an upstream pumping unit controller interface; Figure 2c is a block diagram of a controller for controlling a relay pumping setup according to another embodiment; the controller comprises a liquid level sensor interface, a processing unit, a pumping unit interface, an upstream pumping unit controller interface and a downstream pumping unit controller interface; Figure 3 is a flowchart which shows one embodiment for controlling a relay pumping setup according to one embodiment of the invention; according to a first step, a relay reservoir liquid level indication signal is received and according to a second step, a control signal is provided;

Figure 4 is a flow chart which shows one embodiment for providing the control signal; inter alia, a test is performed in order to find out if the relay reservoir liquid level is greater than a "high-level" threshold;

Figure 5 is a block diagram which shows one embodiment for using the controller for controlling a relay pumping setup; in this embodiment, a relay pump controller controls a pumping unit and an upstream pumping unit controller controls the upstream pumping unit; Figure 6 is a schematic which shows one embodiment where the controller for controlling the relay pumping setup is advantageously used; in this embodiment, the relay pumping setup comprises a single relay reservoir; Figure 7 is a block diagram which shows another embodiment for advantageously using the controller for controlling a relay pumping setup; in this embodiment, two relay reservoirs are provided, an upstream pumping unit is used with a pumping unit associated with the upstream relay reservoir, and a downstream pumping unit is added;

Figure 8 is a schematic, which shows another embodiment where the controller for controlling a relay pumping setup is advantageously used; in this embodiment, the relay pumping setup comprises a downstream relay reservoir and an upstream relay reservoir.

Further details of the invention and its advantages will be apparent from the detailed description included below.

DETAILED DESCRIPTION

In the following description, references to the accompanying drawings are by way of illustration of an example by which the invention may be practiced. It will be understood that other embodiments may be made without departing from the scope of the invention disclosed.

Now referring to Figure 1 , there is shown a prior art relay pumping setup. In this prior art relay pumping setup, an upstream pumping unit 10 (typically comprising an engine which drives a pump end) is connected to a source of water 6 using a first suction hose 15. The upstream pumping unit 10 is further connected to a relay reservoir 14 using a first discharge hose 16. A downstream pumping unit 12 is connected to the relay reservoir 14 using a second suction hose 17. The downstream pumping unit 12 is further connected to a target location 8 where the water is to be discharged using a second discharge hose 18.

The upstream pumping unit 10 is drafting water from a water source 6 and is discharging the water to the relay reservoir 14. The downstream pumping unit 12 is drafting water from the relay reservoir 14 and is discharging the water to the target location 8. The skilled addressee, i.e., one of ordinary skill in the art, will appreciate that the target location 8 may be a fire for instance. The source of water 6 may be a natural source of water such as a river or alternatively, the source of water 6 may be an artificial source of water such as a water truck. It will be appreciated by the skilled addressee that the level of liquid in the relay reservoir 14 may vary. For instance, if the downstream pumping unit 12 stops operating, the liquid level 20 of the relay reservoir 14 will increase. In the case where the upstream pumping unit 10 stops operating, the liquid level 20 of the relay reservoir 14 will decrease. Further, two pumps likely do not pump at the same rate, due in part to component variation and tolerances, and in part to variable losses such as friction and static head. Thus, at one point, the liquid level 20 in the relay reservoir 14 may go beyond a "high-level" threshold. On the

other hand, the liquid level 20 in the relay reservoir 14 may go below a "low-level" threshold. In the first case, the liquid could overflow the relay reservoir 14 while in the second case, the relay reservoir 14 could be emptied, resulting in damage to the downstream pump. In the case where the relay reservoir 14 becomes dry, the downstream pumping unit 12 may choke or go dry resulting in damage to the downstream pumping unit 12.

Now referring to Figure 2a, there is shown one embodiment of a controller 22 for controlling a relay pumping setup comprising a first pumping unit for pumping liquid into a relay reservoir and a second pumping unit for pumping from the relay reservoir to a given location. The controller 22 comprises a relay reservoir liquid level sensor interface 24, a processing unit 26, a pumping unit interface 28 and an upstream pumping unit interface 30. The liquid level sensor interface 24 receives liquid level information from a relay reservoir liquid level sensor (not shown). The pumping unit interface 28 provides an interface to a pumping unit (not shown) with which the controller 22 is collocated. The upstream pumping unit interface 30 provides an interface to an upstream pumping unit (not shown). The liquid level sensor interface 24 may provide for one of a wire and a wireless connection with the relay reservoir liquid level sensor. In the case of a wire connection, the connection may be performed using optic fiber, hard wire, or the like, or any combination thereof. Similarly, the pumping unit interface 28 and the upstream pumping unit interface 30 may provide for a wire or wireless connection with respectively a pumping unit and an upstream pumping unit. A wireless communication interface may operate using a short-range radio link, a cellular data link, a satellite link, or the like, or any combination thereof. The upstream pumping unit interface 30 may communicate directly with the upstream pumping unit or may instead be adapted to communicate with the upstream pumping unit via another controller via one or more two-way communication links. Still in another embodiment, the two-way communication link may be permanent link or a temporary link.

The processing unit 26 processes data as further explained below. The processing unit 26 may be a Field Programmable Gate Array (FPGA), a dedicated processing unit, hard-wired circuitry, or the like, or a combination thereof. The liquid level sensor interface 24 receives a relay reservoir liquid level indication signal and passes the received relay reservoir liquid level indication signal to the processing unit 26. The processing unit 26 receives the liquid level indication signal and provides a pumping unit control signal via the pumping unit interface 28, and an upstream pumping unit control signal via the upstream pumping unit interface 30.

It will be appreciated by the skilled addressee that while it has been shown that the pumping unit interface 28 and the upstream pumping unit interface 30 provide signals to the pumping unit and the upstream pumping unit respectively, the pumping unit interface 28 and the upstream pumping unit interface 30 may as well receive signals from their pumping units respectively and provide those signals to the processing unit 26. In such an embodiment, the data comprised in the signals may be used to create the pumping unit control signals. The skilled addressee will appreciate that this is of great advantage to provide an efficient controlling of the relay pumping setup. In the case of a complex multi-relay reservoir setup, when communicating with a pumping unit, specific data may be relayed to another controller. The skilled addressee will appreciate that such relay of data depends on the desired implementation. Now referring to Fig 2b, there is shown an alternative embodiment of a controller 23 for controlling a relay pumping setup comprising a first pumping unit (upstream pumping unit) for pumping liquid into a relay reservoir and a second pumping unit for pumping from the relay reservoir to a given location. The controller is collocated with the second pumping unit for pumping from the relay reservoir. The controller 23 comprises the liquid level sensor interface 24, the processing unit 26, the pumping unit interface 28 and an upstream pumping unit controller interface 31.

In this embodiment, the upstream pumping unit controller interface 31 communicates with an upstream pumping unit controller controlling the upstream pumping unit. More precisely, the upstream pumping unit controller interface 31 provides an inter-controller communication signal to the upstream pumping unit controller which controls the upstream pumping unit. A communication with another controller is performed using an inter-controller module. Now referring to Figure 2c, there is shown an embodiment of a controller 25 for controlling a relay pumping setup comprising a first pumping unit (upstream pumping unit) for pumping liquid into an upstream relay reservoir, a second pumping unit for pumping from the upstream relay reservoir to a downstream relay reservoir and a third pumping unit (downstream pumping unit) for pumping from the downstream relay reservoir to a given location. The controller 25 is collocated with the second pumping unit. The controller 25 comprises the liquid level sensor interface 24, the processing unit 26, the pumping unit interface 28, an upstream pumping unit controller interface 31 and a downstream pumping unit controller interface 33. In this embodiment, the downstream pumping unit controller interface 33 communicates with a downstream pumping unit controller controlling the downstream pumping unit. More precisely, the downstream pumping unit controller interface 33 receives an inter-controller communication signal from the downstream pumping unit controller controlling the downstream pumping unit. The inter-controller communication signal is indicative of the downstream relay reservoir liquid level. The processing unit 26, responsive to at least one of the received upstream relay reservoir liquid level indication signal and the received downstream control signal. The processing unit 26 also controls the associated pumping unit via the pumping unit interface 28 and the upstream pumping unit via the upstream pumping unit controller interface 31. Now referring to Figure 3, there is shown how the controller controls a relay pumping setup according to one embodiment of the invention.

According to step 32, a relay reservoir liquid level indication signal is received. In one embodiment, the relay reservoir liquid level indication signal is received from a liquid level sensor.

According to step 34, a control signal is provided to at least one of the upstream pumping unit and the downstream pumping unit depending on the received relay reservoir level indication signal.

Now referring to Figure 4, there is shown how to provide a control signal to at least one of the upstream pumping unit and the downstream pumping unit depending on the received relay reservoir level indication signal. According to step 36, a test is performed in order to find out if the relay reservoir liquid level is greater than a "high-level" threshold.

In the case where the relay reservoir level is greater than the "high-level" threshold and according to step 38, a "stop pumping" control signal is provided to the upstream pumping unit. Alternatively, one of a "pump more" control signal and a "start pumping" control signal may be further provided to the downstream pumping unit.

In the case where the relay reservoir liquid level is not greater than the "high- level" threshold and according to step 40, a test is performed in order to find out if the relay reservoir liquid level is lower than a given "low-level" threshold. In the case where the relay reservoir liquid level is lower than the "low-level" threshold and according to step 42, a "stop pumping" control signal is provided to the downstream pumping unit. Alternatively, one of a "pump more" control signal and a "start pumping" control signal may be further provided to the upstream pumping unit. The "pump more" control signal is intended to cause an increase in a pumping speed while the "start pumping" control signal is intended to cause a pump to start pumping.

While an embodiment has been disclosed where two given thresholds are provided, i.e. a "low-level" threshold and a "high-level" threshold in the relay reservoir, the skilled addressee will appreciate that alternatively a single threshold may be provided. Hysteresis may be utilized as well.

Moreover, more than two given thresholds may be provided for the relay reservoir, and control signals may be provided depending on the relay reservoir

liquid level and those provided thresholds. Various control strategies may be designed and implemented to optimize the discharge of the water. The control strategies may be based on various parameters of the pumping units, such as pumping speed. Now referring to Figure 5, there is shown one embodiment where the controller for controlling a relay pumping unit is advantageously used. In this embodiment, the relay pumping setup comprises a pumping unit 54, a relay pump controller 52 for the pumping unit 54, a liquid level monitor (or sensor) 50, an upstream pumping unit controller 56 and an upstream pumping unit 58. The liquid level monitor 50 provides a relay reservoir liquid level indication signal. The relay pump controller 52 is collocated with the pumping unit 54. The relay pump controller 52 for the pumping unit 54 provides a pumping unit control signal for controlling the pumping unit 54 as well as inter-controller data to the upstream pumping unit 56. The upstream pumping unit controller 56 exchanges inter-controller data with the (downstream) relay pump controller 52 and further provides an upstream pumping unit control signal to the upstream pumping unit 58 and receives an optional pumping unit feedback signal from the upstream pumping unit 58. Now referring to Figure 6, there is shown how the embodiment disclosed in Figure 5 operates.

An upstream pumping unit 62 is connected to a source of water 64 using a first suction hose 78. The upstream pumping unit 62 pumps the water to a relay reservoir 72 using a first discharge hose 80. The pumping unit 70 is connected to the relay reservoir 72 using a second suction hose 81 and the pumping unit is connected to a remote location 66 using a second discharge hose 82.

More precisely, the upstream pumping unit 62 pumps water from the water source 64 using the first suction hose 78 and discharges the pumped water into the relay reservoir 72 using the first discharge hose 80. The pumping unit 70 pumps water from the relay reservoir 72 using the second suction hose 81 to the target location 66 using the second discharge hose 82.

It will be appreciated that the upstream pumping unit 62 as well as the pumping unit 70 are controlled respectively by the controller for the upstream unit 60 and the relay pump controller 68.

As disclosed in Figure 5, the controller for the upstream pumping unit 60 communicates with the relay pump controller 68 using an inter-controller communications signal in one embodiment. The relay pump controller 68 further receives a relay reservoir liquid indication level signal from a relay reservoir liquid indication sensor 74. The skilled addressee will appreciate that using the algorithm disclosed in Figure 4, it is possible to easily control the upstream pumping unit 62 as well as the pumping unit 70.

For instance, if the relay reservoir liquid level is higher than a "high-level" threshold, the relay pump controller 68 may easily provide a control signal to the upstream pumping unit 62 via the inter-controller communication channel. In this embodiment, the control signal is a "stop pumping" control signal or alternatively a "reservoir full" status signal. Alternatively, in the case where the relay reservoir liquid level is lower than a "low-level" threshold, the relay pump controller 68 may send a signal to the pumping unit 70 as well as to the upstream pumping unit 62 via the controller for the upstream pumping unit 60. In such embodiment, the relay pump controller 68 may send a "stop pumping" signal (or alternatively, a "reservoir empty" status signal) to the pumping unit 70 as well as a "start pumping" signal to the upstream pumping unit 62 in order to avoid any damage to the pumping unit 70.

Now referring to Figure 7, there is shown an alternative embodiment where the controller for controlling a relay pumping setup may be advantageously used. In the embodiment disclosed in Figure 7, the relay pumping setup comprises an upstream relay reservoir and a downstream relay reservoir, which are not shown in Fig. 7.

An upstream relay reservoir liquid level monitor 90 is located in the upstream relay reservoir and a downstream relay reservoir liquid level monitor 84 is located in the downstream relay reservoir.

More precisely, the relay pumping setup comprises a downstream relay reservoir liquid level monitor 84, a downstream pumping unit controller 86, a downstream

pumping unit 88, an upstream relay reservoir liquid level monitor 90, a relay pump controller 92, a pumping unit 94, an upstream pumping unit controller 96 and an upstream pumping unit 98.

The upstream relay reservoir liquid level monitor 90 provides an upstream relay reservoir liquid level indication signal to the relay pump controller 92 while the downstream relay reservoir liquid level monitor 84 provides a downstream relay reservoir liquid level indication signal to the downstream pumping unit controller 86. The downstream pumping unit controller 86 communicates with the relay pump controller 92 via a downstream inter-controller communication channel while the relay pump controller 92 communicates with the upstream pumping unit controller 96 via an upstream inter-controller communication channel. The downstream pumping unit controller 86 provides a downstream pumping unit control signal to the downstream pumping unit 88 and may further receive a feedback or status signal from the downstream pumping unit 88.

Similarly, the relay pump controller 92 and the upstream pumping unit controller 96 provide control signals to their respective associated pumping units and optionally may receive feedback, such as for example a status signal, from their respective associated pumping units. Now referring to Figure 8, there is shown an embodiment where the setup for the relay pumping setup shown in Figure 7 is advantageously used. In this embodiment, the upstream pumping unit 98 is connected to a water source 104 using the first suction hose 106. The upstream pumping unit 98 is further connected to an upstream relay reservoir 100 using a first discharge hose 108. The pumping unit 94 is connected to the upstream relay reservoir 100 using a second suction hose 107 and is further connected to a downstream relay reservoir 102 using a second discharge hose 1 10. The downstream pumping unit 88 is connected to the downstream relay reservoir 102 using a third suction hose 1 1 1. One of ordinary skill in the art would recognize that there could be additional reservoirs and corresponding pumps and controllers. For illustrative purposes, only one such "midstream" configuration is shown in Fig. 8.

More precisely, the upstream pumping unit 98 pumps water from the water source 104 using the first suction hose 106 and discharges the water into the upstream relay reservoir 100 via the first discharge hose 108, while the pumping unit 94 pumps water from the upstream relay reservoir 100 via the second suction hose 107 and discharges the water into the downstream relay reservoir 102 via the second discharge hose 1 10. The downstream pumping unit 88 pumps water from the downstream relay reservoir 102 via the third suction hose 1 1 1 and discharges the water to the target location 1 14 via the third discharge hose 1 12. It will be appreciated that the upstream pumping unit 98 operates according to an upstream pumping unit control signal provided by the upstream pumping unit controller 96; the pumping unit 94 operates according to a pumping unit control signal provided by the relay pump controller 92; and the downstream pumping unit 88 operates according to a downstream pumping unit control signal provided by the downstream pumping unit controller 86. It will be appreciated that the downstream pumping unit controller 86 provides an inter-controller communication signal to the relay pump controller 92. It will be further appreciated that the relay pump controller 92 may optionally share data via the inter-controller communication channel with the upstream pumping unit controller 96. Alternatively, the downstream pumping unit controller 86, the controller for the pumping unit 92 and the upstream pump controller 96 may share a single inter-controller communication channel.

It will be appreciated that the inter-controller communication signal data may be shared over one of a permanent link and/or a temporary link. The skilled addressee will appreciate that while two embodiments have been disclosed, the controller may be used in many other embodiments.

Moreover, using the inter-controller communication signal, data may be centralized at a given location, which may be a controller, or any other processing unit operatively connected to the controller. The skilled addressee will appreciate that the controlling of the relay pumping setup does not require more than one person to operate since it is possible to centrally gather the data and control the setup efficiently. Now referring back to Fig. 6, there is shown an optional central

controller 93 for collecting the inter-controller communication signal provided by the relay pump controller 68 and the controller for the upstream pumping unit 60.

Similarly, the optional central controller 93 for collecting the inter-controller communication signal may be provided in the embodiment disclosed in Fig. 8. In such case, the inter-controller communication signal received by the optional central controller 93 is provided by at least one of the controller for the downstream pumping unit 86, the controller for the pumping unit 92 and the controller for the upstream pumping unit 96.

It will be appreciated that the method for providing the control signal disclosed herein may be stored as machine-executable instructions in a machine-readable medium.

The skilled addressee will appreciate that the pumping units may be started or stopped individually or collectively by an operator from a central location.

Alternatively, the pumping units may be started or stopped in a distributed fashion.

Also it will be appreciated that devices similar to that described in US Patent

Application N°11/332,742 entitled "Multi-drive converter unit for driving multiple fire suppression accessories" that was filed on January 13, 2006 or US Patent

Application N°1 1/398,808 entitled "Pump controller for controlling pumps connected in tandem" that was filed on April 6, 2006, both of which are hereby incorporated by reference, may be used.

It will be appreciated by the skilled addressee that Figs. 1 , 6 and 8 are not drawn to scale.

Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.

For example, in one scenario, two pumps/hoses could be used in parallel

(redundancy) to fill or draw from a reservoir, where one backs up the other. A controller according to an embodiment of the present invention could start the idle pump when the other fails, while taking reservoir levels into account.