Patent Application
20190160497
Portable pressure washers have been manufactured worldwide for residential and industrial uses. A pressure washer (also known as a power washer) is a high-pressure mechanical sprayer used to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles and concrete surfaces. There are typically two versions of a portable pressure washer design; these being either cold water or hot water machines. The pressure washer may be connected to an existing water supply, such as a garden hose, or may store water in an attached tank. There may be an on/off switch for controlling the water stream and certain models may enable an operator to adjust the water pressure.
The basic components of a portable cold-water power washer include a prime-mover, such as an internal combustion engine or electric motor, mounted on a mobile cart, complete with fuel storage and delivery to the engine. The engine may be coupled to a high-pressure pump, either directly or via a drive mechanism, such as a serpentine belt. The pump may be equipped with an unloader valve that enables an operator to adjust the output performance of the pressurized water stream (i.e., pressure and flow). A high-pressure hose may be attached to an output port of the high-pressure pump and terminated at a handheld ‘wand’ equipped with a trigger-release (i.e., hand valve) that permits the operator to control the flow (on or off) as desired. An inlet port of the high-pressure pump may be fitted with a hose hookup, typically for connection to a garden spigot.
The configuration of the hot water pressure washer may be more complicated than the cold-water power washer due a need to heat the incoming water to a substantial temperature. With typical flow rates of 2-4 gallons per minute (GPM) and a required temperature rise more than 120-140 degrees Fahrenheit, 30-50 kilowatts (kW) of thermal energy may be required on a continuous basis.
The basic components of a portable hot water power washer may include a prime-mover, such as an internal combustion engine, mounted on a mobile cart, complete with fuel storage and delivery to the engine. The engine may be coupled to a high-pressure pump, either directly or via a drive mechanism, such as a serpentine belt. The pump is typically equipped with an unloader valve (i.e., pressure relief valve) that enables the user to adjust the output performance of the pressurized water stream (pressure and flow).
An outlet port of the high-pressure pump may be plumbed to a flame-fired burner assembly. The burner assembly typically incorporates a continuous-coil air-to-water heat exchanger mounted over a gasoline or diesel-fired flame burner. The top of the burner may include an exhaust hood. A high-pressure hose may be attached to an output port of the burner assembly and terminated at a handheld ‘wand’ equipped with a trigger-release (i.e., hand valve) that permits the operator to control the flow (on or off) as desired. An inlet port of the high-pressure pump may be fitted with a hose hookup, typically for connection to a garden spigot.
Due to the complexity of the hot water pressure washer design versus a cold-water pressure washer, the cost of the hot water pressure washer is typically an order of magnitude (5× to 10×) higher than the cost of a cold-water pressure washer. This significant cost variance has hindered successful commercialization of a hot water pressure washer into the consumer and residential markets worldwide.
Disclosed is a hot water pressure washer that employs a high-pressure pump for producing a stream of pressurized water and a hydrodynamic heater for heating the water. A prime-mover, such as an internal combustion engine, may be used to generate rotational torque for powering the high-pressure pump and the hydrodynamic heater. The hydrodynamic heater may include an inlet port fluidly connectable to a water source, such as a municipal water supply, and an outlet port fluidly connected to an inlet port of the high-pressure pump. The hot water pressure washer may include an unloader valve that has an inlet port fluidly connected to an outlet port of the high-pressure pump. The unloader valve may have a first outlet port fluidly connected to the inlet port of the hydrodynamic heater through a bypass passage and a second outlet port fluidly connectable to a high-pressure hose. A handheld wand may be attached to the high-pressure hose and include a trigger activated hand valve that may be selectively actuated by an operator to control a stream of water discharged from the handheld wand. The unloader valve may be adjusted to control distribution of the high-pressure water discharged from the high-pressure pump between the bypass passage and the high-pressure hose. The hot water pressure washer may employ an exhaust gas recovery heat exchanger operable to transfer heat from the internal combustion engine exhaust gas to the stream of water passing through the high-pressure power washer. An engine oil cooler may be used to transfer heat from the engine oil to the stream of water. The hot water pressure washer may employ a pre-heat tank for temporarily storing a quantity of heated fluid for future use.
The various features, advantages and other uses of the present apparatus will become more apparent by referring to the following detailed description and drawings, in which:
With reference to
With reference to
Hydrodynamic heater 38 may include a drive shaft 43 and a drive means 42 attached to an end of the drive shaft 43. Drive means 42 may include a pulley 44 engageable with the hydrodynamic heater drive belt 45. Hydrodynamic heater drive belt 45 transfers torque generated by internal combustion engine 26 to the drive shaft of the hydrodynamic heater 38. Alternatively, hydrodynamic heater 38 and high-pressure pump 30 may be driven by a single drive belt rather than two separate drive belts.
Drive means 42 may include a clutch 46, which may, for example and without limitation, be an electromagnetic clutch. Clutch 46 may be selectively engaged in response to a user input and/or the particular heating requirements of the hot water pressure washer 20. Clutch 46 may be operated to disengage hydrodynamic heater 38 from the power supply, for example, internal combustion engine 26, when no additional heating of the water is required.
Hot water pressure washer 20 may include an exhaust heat recovery heat exchanger 48 as a second source of heat to the water passing through the pressure washer. Although a suitably sized hydrodynamic heater 38 may negate a need to employ exhaust heat recovery heat exchanger 48, it may be beneficial that hot water pressure washer 20 utilize the smallest displacement of internal combustion engine 26 possible, minimizing the system cost as much as possible. Recovery of heat from the engine's exhaust system is effectively ‘free’ energy to the system, thus providing a measurable benefit from incorporating exhaust heat recovery heat exchanger 48. The exhaust heat recovery heat exchanger 48 may be fluidly connected to an exhaust 51 of engine 26. Exhaust gas from engine 26 may enter the exhaust heat recovery heat exchanger 48 at an exhaust inlet port 53. The exhaust gas may pass through the exhaust heat recovery heat exchanger 48 and be discharged to atmosphere though an exhaust output port 55.
Warmed water may be discharged from exhaust heat recovery heat exchanger 48 at a water outlet port 56 and travel through a hydrodynamic heater supply passage 58 to hydrodynamic heater 38. The warmed water may enter hydrodynamic heater 38 at a heater inlet port 60. The water is further heated as it passes through hydrodynamic heater 38.
Heated water may exit hydrodynamic heater 38 at a heater outlet port 62 and pass through a hydrodynamic heater discharge passage 64 to high-pressure pump 30. The water may enter the high-pressure pump 30 at a pump inlet port 66. High-pressure pump 30 operates to pressurize the water. Pressurized water may be discharged from high-pressure pump 30 at an outlet port 68. Water discharged from high-pressure pump 30 may flow to an unloader valve 36 and enter the valve at a valve inlet port 70.
Unloader valve 36 may include a first outlet port 72 fluidly connected to water inlet port 54 of exhaust heat recover heat exchanger 48 by way of a bypass passage 76. A high-pressure spray hose 78 fluidly connects a second outlet port 80 of the unloader valve 36 to a handheld wand 82 equipped with a trigger-activated hand valve 84 that permits the user to control the flow of heated water discharged from the handheld wand 82. When operating hot water pressure washer 20, the user may cycle triggering of the handheld wand 82 on a periodic basis; perhaps 30-60 seconds engaged, followed by 30-60 seconds disengaged. The unloader valve 36 may be selectively adjusted to control a flow distribution of water between bypass passage 76 and high-pressure spray hose 78. The unloader valve 36 may also operate as a pressure relief valve.
Referring to
Water, at an elevated temperature versus the source water temperature (i.e., temperature of the water at inlet 50), may exit exhaust heat recovery heat exchanger 48 at water outlet port 56 and enter hydrodynamic heater 38 at heater inlet port 60. Water may exit hydrodynamic heater 38 at heater outlet port 62, further elevated in temperature, and enters high-pressure pump 30 at pump inlet port 66. With unloader valve 36 adjusted to provide minimum pressure relief and maximum pump-outlet pressure, substantially all the water leaving high-pressure pump 30 enters high-pressure spray hose 78 and passes through handheld wand 82, while substantially no water leaving high-pressure pump 30 recirculates via unloader valve 36 to exhaust heat recovery heat exchanger 48.
Referring to
Water, at an elevated temperature versus the source water, exits exhaust heat recovery heat exchanger 48 at outlet port 56 and enters hydrodynamic heater 38 at heater inlet port 60. Water exits hydrodynamic heater 38 at heater outlet port 62, further elevated in temperature, and enters high-pressure pump 30 at pump inlet port 66. Depending on the adjustable setting of unloader valve 36, a portion of the water leaving high-pressure pump 30 at pump outlet port 68 enters high-pressure spray hose 78 and passes through handheld wand 82, while a portion of the water leaving high-pressure pump 30 recirculates, via unloader valve 36, back to water inlet 54 of exhaust heat recovery heat exchanger 48 through bypass passage 76.
With reference to
With reference to
Temporarily blocking the discharge of water from handheld wand 82, determined by the operator's operation of trigger valve 84, enables exhaust heat recovery heat exchanger 48 to substantially pre-heat the water as it continuously circulates through bypass port 72 of unloading valve 36, exhaust heat recovery heat exchanger 48, hydrodynamic heater 38 (further pre-heating the water) and high-pressure pump 30. This ‘bypass loop’ may continue until trigger valve 84 on handheld wand 82 is depressed to allow water to discharge from handheld wand 82 to atmosphere. When the flow to atmosphere is reestablished by actuating trigger valve 84, unloader valve 36 may cease or partially cease bypassing the water through bypass passage 76. The amount of bypass fluid may be determined by the operator's manual adjustment of unloader valve 36.
During extended operation of hot water pressure washer 20, when handheld wand trigger valve 84 is not depressed, the water present within the ‘bypass loop’, may eventually elevate to an undesirable temperature and/or pressure level. Several design features may be incorporated into the hot water pressure washer 20, either individually or in combination, that may optimize safe and efficient operation of the hot water pressure washer 20. For example, as illustrated in
Although the following feature may be incorporated anywhere within the hydraulic ‘bypass loop’, an over-pressure prevention feature may be located within exhaust heat recovery heat exchanger 48, as illustrated for example, in
With reference to
Hot water pressure washer 20 may include various alternative configurations. For example, with reference to
With reference to
The hot water pressure washer 20 may employ an inline pre-heat tank 88 fluidly integrated within the ‘bypass loop’ in conjunction with, or in place of, the exhaust heat recovery heat exchanger 48, as illustrated, for example, in
With reference to
Configurations of the hot water pressure washer 20 having the exhaust heat recovery heat exchanger 48 located downstream of high-pressure pump 30 (as illustrated, for example, in
With reference to
Hot water pressure washer 20 may employ a water-cooled internal combustion engine, similar to internal combustion engine 26, as prime-mover 22. Thermal energy may be extracted from an engine cooling circuit used to cool the water-cooled internal combustion engine and combined with the power washer water heating circuit.
It is intended that the scope of the present methods and apparatuses be defined by the following claims. However, it must be understood that the disclosed systems and methods may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. It should be understood by those skilled in the art that various alternatives to the configurations described herein may be employed in practicing the claims without departing from the spirit and scope as defined in the following claims. The scope of the disclosed systems and methods should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future examples. Furthermore, all terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc., should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. It is intended that the following claims define the scope of the device and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. In sum, it should be understood that the device is capable of modification and variation and is limited only by the following claims.
