IDLE DOWN CONTROL FOR A PRESSURE WASHER
A method of controlling the speed of an engine includes positioning a throttle at an operating position between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed, collecting a fluid within a manifold, sensing a pressure within the manifold, and adjusting the operating position of the throttle in response to the sensed pressure. When the sensed pressure is low, the throttle is moved toward the idle position and when the pressure is high, the throttle is moved toward the normal speed position. The method further includes positioning an unloader downstream of the manifold, the manifold configured in one of a first position in which the unloader directs fluid from the manifold to the pump, and a second position in which the unloader directs fluid to a point of use.
This application is a continuation of U.S. application Ser. No. 11/729,692 filed Mar. 29, 2007, now U.S. Pat. No. ______, which claims the benefit of U.S. Provisional Patent Application No. 60/831,330 filed Jul. 17, 2006, the entire contents of each are hereby incorporated by reference herein.
BACKGROUNDThe present invention relates to an idle down control for an engine. More particularly, the present invention relates to an idle down control for an engine that provides power for a pressure washer.
Pressure washers use high-pressure liquid, typically water, to clean surfaces such as driveways, decks, walls, and the like. Generally, the pressure washer includes an engine that provides power to a pump. The pump operates to provide high-pressure fluid to a wand or a gun that includes a trigger mechanism that is actuated by the user to discharge the high-pressure fluid. Generally, the user squeezes the trigger with one hand and supports the discharge end of the gun with the other hand during use.
During periods when high-pressure water is not required, the user releases the trigger and high-pressure water from the pump discharge is directed back to the pump intake.
SUMMARYThe invention provides an idle down control that includes a pressure sensor that detects a pressure downstream of a pump. An actuator moves in response to the detected pressure between a first position in which the engine throttle is forced to an idle position, and a second position in which the engine throttle is free to move between the idle position and a wide open position. The pressure sensor measures the pressure at the pump outlet manifold such that a drop in pressure results in movement of the actuator to the first position. The position of the sensor is such that it detects a drop in pressure when fluid is being bypassed from the pump outlet to the pump inlet.
In one construction, the invention provides a method of controlling the speed of an engine that powers a pressure washer pump. The method includes positioning a throttle at an operating position between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed. The method also includes collecting a fluid within a manifold immediately as it is discharged from the pump, sensing a pressure within the manifold, and adjusting the operating position of the throttle in response to the sensed pressure. When the sensed pressure is low, the throttle is moved toward the idle position and when the pressure is high, the throttle is moved toward the normal speed position. The method further includes positioning an unloader downstream of the manifold and configuring the unloader in one of a first position in which the unloader directs fluid from the manifold to the pump such that the sensed pressure is low, and a second position in which the unloader directs fluid from the manifold to a point of use and the sensed pressure is high.
In another construction, the invention provides a method of controlling the speed of an engine that powers a pressure washer pump. The method includes configuring a throttle to operate between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed. The method also includes providing a pressure sensor at a manifold to sense pressure of the fluid immediately as it is discharged from the pump and providing a linkage between the pressure sensor and the throttle to adjust the operating position of the throttle in response to the sensed pressure. When the sensed pressure is low, the throttle is moved toward the idle position and when the sensed pressure is high, the throttle is moved toward the normal speed position. The method further includes providing an unloader downstream of the manifold and the pressure sensor. In a first position, the unloader directs fluid from the manifold back to the pump, and in a second position, the unloader directs fluid from the manifold to a point of use.
In yet another construction, the invention provides a pressure washer configured to output a pressurized fluid to a point of use. The pressure washer includes an engine having a throttle movable between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed. The pressure washer also includes a pump having an inlet and an outlet that discharges fluid, said pump powered by the engine to pressurize the fluid and a manifold positioned to immediately receive the fluid discharged from the pump outlet such that a manifold pressure is substantially equal to a pump discharge pressure. An unloader is positioned between the manifold and the point of use. The unloader is configurable in a first configuration in which fluid flows from the manifold to the point of use and a second configuration in which fluid flows from the manifold to the pump inlet, and wherein the manifold pressure is high when the unloader is in the first configuration and is low when the unloader is in the second configuration. A pressure sensor is configured to continuously detect the manifold pressure without flow passing through the sensor and an actuator is responsive to the detected manifold pressure to move between a first position when the detected manifold pressure is low, and a second position when the detected manifold pressure high. A linkage is connected between the actuator and the throttle to move the throttle to the idle position when the actuator is in the first position.
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 direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
The gun 15 includes a trigger assembly 35 that allows the user to selectively discharge a flow of water from the gun 15. Typically, the user squeezes the trigger 35 to open a valve (not shown) and begin the discharge of high-pressure fluid. When the user disengages the trigger 35, the valve closes, and high-pressure flow is inhibited from exiting the gun 15.
With reference to
The engine 20 also includes a crankcase 55, a piston (not shown), a crankshaft (not shown), and one or more cam shafts (not shown). The crankshaft rotates in response to reciprocation of the piston to produce usable shaft power. The cam shaft or shafts are coupled to the crankshaft such that they rotate at one-half the crankshaft speed to actuate intake and exhaust valves for the engine 20, as is well known in the art.
A governor 60 is coupled to the throttle 50 to control the throttle position to maintain the engine 20 at the desired engine speed during operation. The governor 60 includes a speed sensor (not shown) that senses the actual operating speed of the engine 20. If a typical mechanical governor is used, flyweights rotate in response to the rotation of the engine crankshaft or cam shaft such that the flyweights rotate at the engine speed, or one-half the engine speed (the cam shaft speed). In the illustrated construction, the speed sensor engages a governor shaft 65 that extends out of the crankcase 55 and engages a governor arm 70. The governor arm 70 moves through an arc in response to changes in speed of the engine 20.
A link arm 75 includes a first end 80 that connects to the governor arm 70 and a second end 85 that is coupled to the throttle 50. Thus, movement of the governor arm 70 produces a corresponding movement of the throttle 50. A governor spring 90 is connected to the engine 20 and to the governor arm 70 to bias the arm 70 toward a first or wide open throttle direction.
The governor arm 70 includes an extension 95 that defines a plurality of apertures 100. A second spring 105 includes a first end 110 that is coupled to the extension 95 using one of the apertures 100, and a second end 115 coupled to an idle control lever 120. The spring 105 can be connected to any one of the apertures 100 to adjust the effect of the spring 105.
The idle control lever 120 is pivotally coupled to the engine 20 such that it rotates substantially freely about an axis. An idle lever 125 is coupled to the idle control lever 120 and an idle down controller 130.
With reference to
The actuator 145 is movably supported by the housing 135 such that it can move between an idle position (shown in
As shown in
The pump 25 discharges high-pressure fluid to a manifold 195 attached to the outlet of the pump 25. The manifold 195 (manifold 195a in the example shown in
Returning to
The operation of the idle down controller 130 will be described with reference to
The high-pressure within the idle down controller 130 forces the actuator 145 inward against the biasing spring 140 toward the normal speed position such that the governor 60 can control the engine speed. As illustrated in
When the user releases the trigger 35, a pressure increase occurs within the hose 30 and the gun 15. The pressure increase forces the unloader valve 200 (
The ability to reduce the engine speed when high-pressure fluid is not required reduces wear on both the engine 20 and the pump 25. In addition, reducing the engine speed can improve the fuel economy of the engine 20 in some situations.
The positioning of the idle down controller 130 results in a very simple system. The idle down controller 130 is directly coupled to the engine 20 with a single pressure line 210 between the pump 25 and the controller 130. In addition, the operation of the controller 130 is such that the controller 130 need not be overly sensitive because the difference in pressure between the high-pressure fluid (during discharge) and the low-pressure fluid (during bypass) is typically in excess of 1000 psi. For example, many types of pressure washers operate with a manifold pressure of between about 2000 psi and 4000 psi during fluid discharge. After the trigger 35 is released and the unloader valve 200 (
In addition, the present device moves the engine throttle 50 to the idle position in response to a drop in pressure, rather than an increase in pressure. Thus, should the pressure line 210 develop a leak or a clog, the pressure drop would likely result in the engine 20 idling rather than operating at full speed.
It should be noted that while the foregoing describes the invention as being applied to an engine powered pressure washer, other constructions may be applied to motor driven pressure washers. In these arrangements, the idle down controller 130 actuates a device that is operable to reduce the rotational speed of the motor or stop the motor. For example, in one construction, the idle down controller 130 moves a switch that opens a circuit between the motor and the power supply to stop rotation of the motor. In other constructions, the idle down controller 130 moves a device that varies the flow of power to the motor. For example, a variable capacitor or a variable resistor could be employed. In still other constructions a frequency varying device is used to reduce the frequency of the electrical current provided to the motor, thereby slowing the motor.
Thus, the invention provides, among other things, an idle down controller 130 that responds to pressure changes within the manifold 195 to reduce the engine speed to an idle speed in response to the closure of a valve in a pressure washer gun 15.
Claims
1. A method of controlling the speed of an engine that powers a pressure washer pump, the method comprising:
- configuring a throttle to operate between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed;
- collecting a fluid within a manifold immediately as it is discharged from the pump;
- sensing a pressure within the manifold;
- adjusting the operating position of the throttle in response to the sensed pressure, wherein when the sensed pressure is low, the throttle is moved toward the idle position and when the pressure is high, the throttle is moved toward the normal speed position;
- positioning an unloader downstream of the manifold; and
- configuring the unloader in one of a first position in which the unloader directs fluid from the manifold to the pump such that the sensed pressure is low, and a second position in which the unloader directs fluid from the manifold to a point of use and the sensed pressure is high.
2. The method of claim 1, wherein the sensing a pressure within the manifold step includes sensing the pressure with a sensor that does not allow fluid to pass through the sensor.
3. The method of claim 1, wherein the difference between the low sensed pressure and the high sensed pressure is greater than 1,000 psi.
4. The method of claim 1, wherein the difference between the low sensed pressure and the high sensed pressure is greater than 1,700 psi.
5. The method of claim 1, wherein the fluid passes through the unloader when the unloader is in the first position and the second position.
6. The method of claim 1, further comprising opening a valve to configure the unloader in the second position.
7. The method of claim 6, further comprising closing the valve to configure the unloader in the first position.
8. A method of controlling the speed of an engine that powers a pressure washer pump, the method comprising:
- configuring a throttle to operate between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed;
- providing a pressure sensor at a manifold to sense pressure of the fluid immediately as it is discharged from the pump;
- providing a linkage between the pressure sensor and the throttle to adjust the operating position of the throttle in response to the sensed pressure, wherein when the sensed pressure is low, the throttle is moved toward the idle position and when the sensed pressure is high, the throttle is moved toward the normal speed position;
- providing an unloader downstream of the manifold and the pressure sensor, wherein in a first position the unloader directs fluid from the manifold back to the pump, and in a second position the unloader directs fluid from the manifold to a point of use.
9. The method of claim 8, wherein the sensor is arranged so that it does not allow fluid to pass through the sensor.
10. The method of claim 1, wherein the difference between the low pressure and the high pressure is greater than 1,000 psi.
11. The method of claim 1, wherein the difference between the low pressure and the high pressure is greater than 1,700 psi.
12. The method of claim 1, wherein the fluid passes through the unloader when the unloader is in the first position and the second position.
13. A pressure washer configured to output a pressurized fluid to a point of use, the pressure washer comprising:
- an engine having a throttle movable between an idle position that reduces the engine speed to an idle speed, and a normal speed position at which the engine runs at a speed greater than the idle speed;
- a pump having an inlet, and an outlet that discharges fluid, said pump powered by the engine to pressurize the fluid;
- a manifold positioned to immediately receive the fluid discharged from the pump outlet such that a manifold pressure is substantially equal to a pump discharge pressure;
- an unloader positioned between the manifold and the point of use, the unloader configurable in a first configuration in which fluid flows from the manifold to the point of use and a second configuration in which fluid flows from the manifold to the pump inlet, and wherein the manifold pressure is high when the unloader is in the first configuration and is low when the unloader is in the second configuration;
- a pressure sensor configured to continuously detect the manifold pressure without flow passing through the sensor;
- an actuator responsive to the detected manifold pressure to move between a first position when the detected manifold pressure is low, and a second position when the detected manifold pressure high; and
- a linkage connected between the actuator and the throttle to move the throttle to the idle position when the actuator is in the first position.
14. The pressure washer of claim 13, wherein the difference between the high pressure and the low pressure is in excess of 1,000 psi.
15. The pressure washer of claim 13, wherein the difference between the high pressure and the low pressure is in excess of 1,700 psi.
16. The pressure washer of claim 13, further comprising a valve movable between a closed position and an open position, and wherein the unloader is movable to the first configuration in response to movement of the valve to the open position.
17. The pressure washer of claim 13, further comprising a valve movable between a closed position and an open position, and wherein the unloader is movable to the first configuration in response to movement of the valve to the open position.
Type: Application
Filed: Sep 20, 2011
Publication Date: Jan 26, 2012
Inventor: Richard J. Gilpatrick (Whitewater, WI)
Application Number: 13/236,938
International Classification: F04B 49/24 (20060101);