ENGINE-DRIVEN PUMP

TECHNICAL FIELD

[0001] The present invention relates generally to engine-driven pumps and, in particular, to engine-protection systems for such pumps.

BACKGROUND

[0002] Portable water pumps are used in fighting forest fires or otherfires in remote locations where a water supply from a fire hydrant or firetruck is unavailable. These portable water pumps are typically gas-powered and designed to draw water from a local water source like a lake, pond, river, stream, etc. Atypical portable gas-powered water pump has an internal combustion engine having one or more cylinders, e.g. a two-cycle or four-cycle internal combustion engine. The engine may be mounted to a frame that may be a hand-carrying tube frame or a channel base frame for mounting to a vehicle such as an all-terrain vehicle. Each cylinder of the engine has a spark plug that may be sparked by a battery-powered push-button electric starter and/or a manual recoil pull-cord. These engine-driven pumps may sustain serious damage should they lose prime (i.e. run out of water).

[0003] The prior art has addressed this technical problem by providing the pump with a simple low-pressure shutoff switch that shuts down the engine in the event of a loss of prime, i.e. when the water pressure falls below a certain level. These priorart engine-protection systems require manual intervention when the engine is started because the low-pressure shutoff switch is normally in the shutoff state until there is pressure being produced by the pump. Many prior-art engine-protection systems use a simple toggle switch to bypass the low-pressure shutoff switch when starting the engine. In other words, the toggle switch is a manually operated bypass switch that requires manual user intervention. One significant shortcoming of this system is that if the user forgets to reset the toggle switch, the pump is unprotected. Other prior-art protection systems use a spring-loaded momentary switch that uses a spring to mechanically force the switch back to the operative position. Although this momentary switch addresses the issue of the user potentially failing to reset the switch, the momentary switch is cumbersome to use, requiring the user to hold the switch while starting the engine. For a manual recoil pull-cord starter, this is particularly awkward.

[0004] A technical solution to the problem described above is highly desirable.

SUMMARY

[0005] In general, the present specification discloses an engine-driven pump system having an internal combustion engine and a pump driven by the engine. To protect the pump, a protection system is provided. The protection system includes a pressure-sensing switch that shuts off the engine when the pressure in the pump is too low, thereby protecting the pump from damage. The protection system includes a protection circuit that has a relay that activates the pressure-sensing switch when the alternator of the engine is generating a higher voltage when running at normal operating speed. The relay deactivates the pressure-sensing switch when the alternator is generating a lower voltage when starting the engine. This protection system thus ensures that the pump is protected automatically without requiring manual intervention to set or reset the protection.

[0006] An aspect of the disclosure is a protection system for automatically protecting an engine-driven pump system. The protection system has a pressuresensing switch that senses a water pressure in the pump and, in response to detecting that the water pressure in the pump is below a predetermined pressure level, shuts off the engine. The protection system includes a relay electrically connected to an alternating current source of the engine, the relay detecting an engine voltage for the alternating current source of the engine. The relay compares the engine voltage to a first and second predetermined voltages. The relay is configured to: if the engine voltage is equal to or higher than the first predetermined voltage, turn on the pressuresensing switch to protect the pump; and if the engine voltage is lower than the second predetermined voltage, turn off the pressure-sensing switch to enable the engine to be started.

[0007] Another aspect of the disclosure is an engine-driven pump system comprising an engine, a pump mechanically connected to the engine and a protection system to automatically protect the pump from damage due to a loss of prime. The protection system comprises a pressure-sensing switch that senses a water pressure in the pump and, in response to detecting that the water pressure in the pump is below a predetermined pressure level, shuts off the engine. The protection system also comprises a relay electrically connected to an alternating current source of the engine, the relay detecting an engine voltage for the alternating current source of the engine, wherein the relay compares the engine voltage to a first predetermined voltage and to a second predetermined voltage wherein the first predetermined voltage is higher than the second predetermined voltage. The relay is configured to: if the engine voltage is equal to or higher than the first predetermined voltage, turn on the pressuresensing switch to protect the pump; and if the engine voltage is lower than the second predetermined voltage, turn off the pressure-sensing switch to enable the engine to be started.

[0008] Yet another aspect of the disclosure is method of automatically protecting a pump of an engine-driven pump system. The method comprises steps of sensing a water pressure in the pump using a pressure-sensing switch and, in response to detecting that the water pressure in the pump is below a predetermined pressure level, shutting off the engine. The method also comprises a step of detecting, using a relay electrically connected to an alternating current source of the engine, an engine voltage for the alternating current source of the engine. The method further entails comparing, using the relay, the engine voltage to a first predetermined voltage and to a second predetermined voltage wherein the first predetermined voltage is higher than the second predetermined voltage. If the engine voltage is equal to or higher than the first predetermined voltage, method involves turning on the pressure-sensing switch to protect the pump. If the engine voltage is lower than the second predetermined voltage, the method involves turning off the pressure-sensing switch to enable the engine to be started.

[0009] The foregoing presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to identify essential, key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later. Other aspects of the invention are described below in relation to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Further features and advantages of the present technology will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0011] FIG. 1 depicts an engine-driven pump system in accordance with an embodiment of the present invention.

[0012] FIG. 2 is a circuit diagram of a direct current (DC) implementation of a protection circuit that provides a protection system for the pump.

[0013] FIG. 3 is a circuit diagram of an alternating current (AC) implementation of a protection circuit that provides a protection system for the pump.

[0014] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

[0015] FIG. 1 depicts an engine-driven pump system in accordance with an embodiment of the present invention. The engine-drive pump system is designated generally by reference numeral 10. As depicted in FIG. 1 , the engine-drive pump system 10 includes an engine 20 and a pump 30 that is mechanically connected to the engine so as to be driven by the engine. The engine 20 in these embodiments is a gas engine, i.e. a two-cycle or four-cycle internal combustion engine having one or more cylinders. The engine may be started using any suitable ignition system, e.g. by pulling a manual recoil pull-cord or by a battery-powered electric starter. The engine has a gas tank and an oil reservoir. The engine may have an oil filter. The engine has an air intake and an exhaust. The engine may have an air filter.

[0016] The pump 30 of this engine-driven pump system 10 may be a multistage centrifugal water pump. However, in other embodiments, it may be a single-stage water pump. The pump 30 has a housing. The housing has a water inlet for receiving water into the housing and a water outlet for expelling the water from the housing. [0017] As further shown in FIG. 1 , the engine-driven pump system 10 includes a protection system 40 that includes a protection circuit as will be described in greater detail below. Two examples of a protection circuit are presented below and illustrated in FIGS. 2 and 3.

[0018] As further depicted in FIG. 1 , the engine-driven pump system 10 includes a handle or frame 50 to carry the engine-driven pump system. The frame 50 may be a hand-carrying tube frame or a channel base frame for mounting to a vehicle such as an all-terrain vehicle. The engine-driven pump system 10 is primarily intended to function as a portable water pump unit. This portable water pump unit is particularly useful for firefighting, especially fighting forest fires or brush fires in remote places where there are no fire hydrants and which are inaccessible to firetrucks. The pump unit may be used to draw water from a local water source such as a lake, pond, river or stream and to discharge the water from a hose to extinguish the fire. The pump may also be used in other water-pumping applications outside of the field of firefighting.

[0019] As depicted in FIG. 1 , the engine-driven pump system 10 includes, or is connectable to, an intake hose 60 for drawing water from a water source 65 such as a lake, pond, river or stream. The intake hose 60 is connected to the water inlet of the pump 30. The engine-driven pump system 10 includes, or is connectable to, an outlet hose, e.g. a fire hose 70 for fighting a fire such as a forest fire or brush fire.

[0020] FIGS. 2 and 3 depict a protection system for automatically protecting the pump 30 of an engine-driven pump system 10. In FIGS. 2 and 3, the engine 20 has, or is connected to, an alternator 22 (i.e. an electrical generator), a voltage regulator 24 (i.e. a rectifier), a battery 26, an ignition coil 28 and a spark plug 29 for creating a spark for combusting gas (fuel) and oxygen-containing air inside a cylinder of the engine 20. As depicted in FIGS. 2 and 3, the pump 30 is protected by a pressuresensing switch 32. This pressure-sensing switch 32 opens and closes in response to a sensed water pressure in the pump in order to protect the pump 30 from damage that would otherwise occur if the water pressure dropped below a safe operating level. As explained above, if the pump loses its prime, the pump can sustain serious damage. The pressure-sensing switch 32 is configured to open the circuit to shut off the engine when the pressure falls below a predetermined minimum water pressure. The pressure-sensing switch 32 is configured to close the circuit to enable the engine to run when the pressure reaches or exceeds the predetermined minimum water pressure.

[0021] The protection system 40 also includes, as part of the protection circuit, a relay 42 that controls the operation of the pressure-sensing switch 32. The relay 42 is preferably a range relay although it could be a latching relay in another embodiment. The relay 42 turns on at a first predetermined voltage (e.g. voltage X) and turns off at a second predetermined voltage (voltage Y). In this implementation, the relay 42 is configured to turn off at much lower voltage, i.e. Y < X. The relay 42 thus activates and deactivates the pressure-sensing switch 32. The relay 42 is triggered by engine voltage, more specifically the voltage of an alternating current source of the engine, such as the alternator of the engine or an ignition coil of the engine. When the voltage in the protection circuit is equal to or higher than the first predetermined voltage, the relay 42 turns on the pressure-sensing switch 32 so that the pump is protected. When the voltage in the protection circuit is lower than the first predetermined voltage, the relay 42 turns off the pressure-sensing switch 32 so that the pump is briefly unprotected to enable the engine to be started and the water pressure to quickly build up. The relay acts therefore like a temporary override that temporarily overrides the pump protection provided by the pressure-sensing switch 32 for a short time to enable the engine to be started up. The start-up voltage generated by the alternator of the engine during engine ignition is much lower than the normal operating voltage generating by the alternator, even when running at idle engine speed. The AC from the ignition coil may also be used. This difference is exploited by the protection system to automatically protect the pump from damage while eliminating the need for any manual intervention in setting or resetting the protection. The protection system thus solves the problems of the prior art that were described above. The protection circuit of this protection system may be implemented in various ways. Two different protection circuits are now described and illustrated in FIGS. 2 and 3.

[0022] FIG. 2 is a DC implementation for a first embodiment of the protection system. In this implementation, the regulator 24 rectifies the AC from the alternator 22 to DC current and then charges the battery 26. As described above, this protection circuit enables the engine 20 to be stopped (shut off) and then restarted without manually resetting the pressure sensor 32. In another embodiment, the DC implementation can use a time-delayed off-relay. The protection circuit of FIG. 2 includes a diode 44 and a capacitor 46 that are placed between the battery 26 and the relay 42.

[0023] FIG. 3 is an AC implementation for a second embodiment of the protection system. In this embodiment, the alternating current is drawn from the primary ignition coil 28, not the alternator 22. As in the circuit of FIG. 2, the AC from the alternator 22 of the engine 20 is rectified by the regulator 24 to charge the battery 26. In a variant, the alternating current may be drawn from the alternator but a different and more complex circuit would be required to handle the higher voltage. The protection circuit of FIG. 3 includes a diode 44 and a capacitor 46 that are placed between the alternator 22 and the relay 42.

[0024] In both protection circuits (FIGS. 2 and 3), the relay 42 activates and deactivates the pressure-sensing switch 32 to selectively protect the pump. As described above, when the voltage in the protection circuit is equal to or higher than the first predetermined voltage, the relay 42 turns on the pressure-sensing switch 32 so that the pump is protected. When the pump is protected, the pressure-sensing switch 32 will shut off the engine to protect the pump from damage if the pump prime is lost. When the voltage in the protection circuit is lower than the second predetermined voltage, i.e. at ignition and start-up of the engine-driven pump, the relay 42 turns off the pressure-sensing switch 32 so that the engine can be started without causing the pressure-sensing switch to shut of the engine. Once the alternator starts to generate a voltage higher than the first predetermined voltage, the relay 42 turns on the pressure-sensing switch 32 to protect the pump. If the prime is lost while the pressure-sensing switch 32 is operating, the pressure-sensing switch 32 protects the pump 30 by shutting off the engine 20. This protection system thus automatically protects the pump without requiring manual intervention.

[0025] For the purposes of interpreting this specification, when referring to elements of various embodiments of the present invention, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, “having”, “entailing” and “involving”, and verb tense variants thereof, are intended to be inclusive and open-ended by which it is meant that there may be additional elements other than the listed elements.

[0026] This new technology has been described in terms of specific implementations and configurations which are intended to be exemplary only.

Persons of ordinary skill in the art will appreciate that many obvious variations, refinements and modifications may be made without departing from the inventive concepts presented in this application. The scope of the exclusive right sought by the Applicant(s) is therefore intended to be limited solely by the appended claims.