Idle down control for a pressure washer

Abstract

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.

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.