Patent Application
20070267063
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
Pressure washers provide a supply of high-pressure fluid for performing various tasks (e.g., paint and stain removal, drain cleaning, driveway cleaning, etc.). Sometimes the water is mixed with a cleaning solution such as soap, ammonia solution, or other chemicals to aid in the cleaning process.
Pressure washers and other pressurized fluid delivery systems often include an engine that drives a high-pressure pump to supply the fluid. A discharge valve (i.e., like a spray gun trigger valve) mounted to the discharge hose from the pump allows the user to remotely control the supply of high-pressure fluid. When the trigger or discharge valve is actuated, a fluid and/or cleaning solution is discharged. When the trigger is released, the flow of fluid stops and either the pump is disengaged, the engine is turned off, or the high-pressure fluid bypasses the outlet to avoid causing damage to the pressurized fluid delivery system. To that end, many pressurized fluid delivery systems include unloader valves that bypass the fluid back to a fluid reservoir or inlet side of the pump when the fluid is not being discharged.
Unloader valves, sometimes referred to as “bypass valves” or “diverter valves”, are used as a control mechanism for pressurized fluid delivery systems. The unloader valve controls the pressure and the direction of flow within the system. Located between the outlet side of the pump and the discharge valve, the unloader valve diverts fluid from the pump outlet back to the pump inlet through a bypass passage when the discharge passage becomes blocked (i.e. when the discharge valve is closed), thereby reducing pressure within the pump. When the discharge passage is unobstructed (i.e. when the discharge valve is open), the unloader valve redirects fluid back to the discharge device and allows the pump pressure to rise back to its normal operating pressure.
Most conventional unloader valves are designed with a high rate spring that will allow the opening of the unloader valve to the bypass position only with a relatively high trapped pressure between the unloader valve and the discharge or trigger valve. With most of these designs, this high-pressure value must be maintained (or “trapped”) within the discharge line and allowed communication against the high rate spring in order to keep the bypass open. If the “trapped line-pressure” is lowered due to leakage, hose expansion, etc., then the high rate unloader spring will close the bypass port in the unloader valve, which can result in pressure pulsations within the pump, engine stalls, or even pump, engine or hose damage.
With reference to
Because the shuttle 24 of the unloader valve 20 does not block the discharge line 106 and spray gun 108 from the return line, high pressure fluid is not trapped in the discharge line 106 (i.e., between the trigger valve of spray gun 108 and the outlet 28 of the unloader valve 20). In fact, pressure in the discharge line 106 is not trapped and is not used to actuate the shuttle 24. Because the spring 30 biases the shuttle 24 to the bypass position, the “actuation” of the shuttle 24 in a direction from the bypass position toward a spray position is flow-triggered and occurs when the discharge valve of the spray gun 108 is open.
An integrated relief valve 42 is configured to open against the biasing force of a regulating spring 44 to relieve excess fluid pressure that may occur within the valve 20. This pressure relief reduces the likelihood of damage to the unloader valve 20 and/or other system components from exposure to excessive pressures. In the illustrated embodiment, an excess pressure port 45 is provided to fluidly connect the fluid inlet 22 to the bypass outlet 26 through the relief valve 42. The fluid inlet 22 and the bypass outlet 26 are otherwise separated from each other during operation when the valve 20 is in the spray position. Excess pressure relieved from the unloader valve 20 is contained within the system 100 and directed back to the fluid reservoir or pump inlet. In other constructions, excess pressure may be vented to the atmosphere or to another low pressure area other than the fluid source.
As illustrated in
When in the bypass position, a space is created between the shuttle seat 66 and the sealing surface 68, which allows fluid to flow along a bypass fluid flow passageway from the fluid inlet 54 and around the shuttle 56 to the bypass outlet 58 (as shown with flow-indicating arrows in
When in the spray position, the seal between the sealing surface 68 and the shuttle seat 66 inhibits the flow of fluid from the fluid inlet 54 to the bypass outlet 58. Thus, the working fluid can flow along a discharge fluid flow passageway from the fluid inlet 54, through a fluid passage or port 70 in the shuttle 56, and out the unloader valve 52 through the discharge outlet 60 (as shown with flow-indicating arrows in
If a fluid pressure within the unloader valve 52 exceeds a predetermined relief pressure, an integrated relief valve 72 is configured to open against the biasing force of a regulating spring 74 to relieve the excess pressure. As described above, this reduces the likelihood of exposing the unloader valve 52 or other system components to excessive pressures. An excess pressure port 76 is provided in the valve 52 to fluidly connect the fluid inlet 54 to the bypass outlet 58 through the relief valve 72, which are otherwise separated from each other during operation when the valve 52 is in the spray position.
An injection port 78 is positioned adjacent a downstream side of the shuttle 56 for operation as described above with respect to the previous embodiment. The injection port 78 includes a check valve 80 and a projecting barbed portion 82 for connection to a hose or the like. The injection port 78 and the check valve 80 may be located on the unloader valve 52 in alternate constructions. Likewise, various methods of attachment known to those of skill in the art may be appropriate for connecting the injection port 78 to a secondary fluid supply.
In both illustrated embodiments, the unloader valve 20, 52 is biased to the bypass position and is actuable to the spray position. The valve 20, 52 is actuable to the spray position by a fluid pressure differential between the fluid inlet 22, 54 and the discharge outlet 28, 60, which acts against a relatively low bias force present in the spring 30, 64. The fluid pressure differential (present during periods of flow through the valve 20, 52) acts on a movable element, such as the shuttle 24, 56. More specifically, a distributed force acts on the movable element in the direction of the fluid flow through the valve 20, 52 when discharging from the spray gun 108 (parallel to an axis of the movable element in some embodiments). In some embodiments, fluid flows through at least one aperture in the movable element (e.g., through the port 32, 70). As illustrated, a reduction in cross-sectional area of the aperture in the movable element (in the direction of fluid flow during discharge from the spray gun 108) provides flow resistance in the form of additional surface area on which the net fluid pressure acts to urge the movable element to the spray position when the spray gun 108 is opened to create a pressure differential between the fluid inlet 22, 54 and the discharge outlet 28, 60. The construction and the configuration of the movable element within the valve 20, 52 place the discharge line 106 in fluid communication with the bypass outlet 26, 58 of the unloader valve 20, 52 when in the bypass position.
In the operation of the pressure washer system 100 having the unloader valve 20, 52, a user closes the discharge or trigger valve of the spray gun 108 when pressurized fluid is not desired to be discharged from the system 100. At that time, pressure builds up between the pump 102 and the spray gun 108, including in the unloader valve 20, 52. This pressure increase is mainly apparent at the discharge end (i.e., between the spray gun 108 and the unloader valve 20, 52) because the upstream end is maintained at high pressure during periods of use (i.e., operation of the pressure washer system 100 with the spray gun 108). When flow is stopped by the closing the discharge valve of the spray gun 108, the pressure differential between the fluid inlet 22, 54 and the discharge outlet 28, 60 of the unloader valve 20, 52 is virtually eliminated. Because the movable element is actuated to the spray position by the flow and requisite pressure differential, the movable element returns to the bypass position with only a small bias force once the flow is stopped. Pressurized fluid is maintained in the discharge line 106 during bypass, but is not trapped and may be maintained at a low pressure level because the pressure in the discharge line 106 is not used to keep the movable element in the bypass position. High pressure cannot build in the discharge line 106 because the discharge outlet 28, 60 is fluidly connected to the bypass outlet 26, 58 of the unloader valve 20, 52, which shunts the fluid flow to a low pressure area such as the fluid reservoir or pump inlet.
In the bypass position, the fluid inlet 22, 54 is in fluid communication with the bypass outlet 26, 58 and also with the discharge outlet 28, 60. Therefore, the pressure of the pressurized fluid at each of the three locations of the unloader valve 20, 52 is substantially equal. In the bypass position, pressurized fluid flows at least from the fluid inlet 22, 54 to the bypass outlet 26, 58, so there must be at least a minute pressure differential therebetween. However, due to the lack of a physical obstruction between the discharge outlet 28, 60 and either of the fluid inlet 22, 54 and the bypass outlet 26, 58, the pressurized fluid at the discharge outlet 28, 60 is maintained at a substantially equivalent pressure as that of the fluid inlet 22, 54 and the bypass outlet 26, 58.
This application claims priority under 35 U.S.C. sec. 119 to provisional patent application No. 60/802,310, filed on May 22, 2006, which is hereby fully incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60802310 | May 2006 | US |
