US20090317262A1

US20090317262A1 - Engine speed control for pressure washer

Info

Publication number: US20090317262A1
Application number: US12/553,904
Authority: US
Inventors: Richard J. Gilpatrick
Original assignee: Briggs and Stratton Corp
Current assignee: Briggs and Stratton Corp
Priority date: 2006-07-17
Filing date: 2009-09-03
Publication date: 2009-12-24

Abstract

A pressure washer includes a water pump and a pressure-sensitive member attached to the water pump. The pressure washer also includes a wire having a first end attached to the pressure-sensitive member. The pressure-sensitive member relays a change in water pressure within the pump through the wire. Additionally the pressure washer includes an engine having a governor spring attached to the wire. Movement of the wire changes a tension of the governor spring. The engine also has a throttle plate attached to the governor spring. The governor spring biases the throttle plate.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This is a continuation-in-part of application Ser. No. 12/436,656, filed May 6, 2009, which is a continuation-in-part of application Ser. No. 11/729,692, filed Mar. 29, 2007, which claims the benefit of Application No. 60/831,330, filed Jul. 17, 2006. Each of U.S. patent application Ser. No. 12/436,656, U.S. patent application Ser. No. 11/729,692, and U.S. Provisional Patent Application No. 60/831,330 are incorporated herein by reference in their entireties.

BACKGROUND

The present invention relates generally to the field of pressure washers. More specifically, the present invention relates to speed control of a pressure washer engine.
Some pressure washer systems include a water pump driven by an internal combustion engine. The water pump includes a recirculation circuit or a bypass through which water may be directed when the sprayer of the pressure washer is not actively spraying. When the sprayer is spraying, the water pump then directs water through the pump to the sprayer, closing the bypass. The engine of the pressure washer pump may run without regard to whether the pump is in bypass mode.

SUMMARY

One embodiment of the invention relates to a pressure washer, which includes a water pump and a pressure-sensitive member attached to the water pump. The pressure washer also includes a wire having a first end attached to the pressure-sensitive member. The pressure-sensitive member relays a change in water pressure within the pump through the wire. Additionally the pressure washer includes an engine having a governor spring attached to the wire. Movement of the wire changes a tension of the governor spring. The engine also has a throttle plate attached to the governor spring, where the governor spring biases the throttle plate.
Another embodiment of the invention relates to a pressure washer, which includes an internal combustion engine having a governor system. The governor system includes a speed-sensing device designed to detect the speed of the engine. The governor system also includes a throttle plate designed to move between a wide open throttle position and a closed position. The throttle plate controls a flow of air and fuel for consumption by the engine. The governor system further includes a linkage between the speed-sensing device and the throttle plate. The linkage adjusts the throttle plate in response to the speed of the engine. Additionally, the governor system includes a governor spring biasing the throttle plate toward the wide open throttle position. The pressure washer also includes a high-pressure water pump powered by the engine and a pressure-sensitive member coupled to the pump. The pressure-sensitive member moves a wire in response to a change in water pressure within the pump. The wire is attached to and designed to load the governor spring.
Yet another embodiment of the invention relates to a pressure washer control system, which includes a water pump and a pressure-sensitive member. The pressure-sensitive member includes a chamber attached to the water pump and a plunger slidable with the chamber. The plunger slides in response to a change in water pressure within the pump. The system also includes wire having a first end attached to the pressure-sensitive member. The pressure-sensitive member adjusts tension in the wire in response to the change in water pressure within the pump. Additionally, the system includes an engine having a governor spring attached to the wire. Adjustment of tension in the wire changes tension in the governor spring. The engine also has a throttle plate attached to the governor spring, where the governor spring biases the throttle plate.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:

FIG. 1 is a perspective view of a pressure washer according to an exemplary embodiment.

FIG. 2 is a perspective view of a water pump of the pressure washer of FIG. 1.

FIG. 3A is a sectional view of a trapped pressure unloader in a first configuration according to an exemplary embodiment.

FIG. 3B is a sectional view of the trapped pressure unloader of FIG. 3A in a second configuration.

FIG. 4 is a perspective view of an internal combustion engine according to an exemplary embodiment.

FIG. 5 is a top view of a speed control assembly for a pressure washer engine according to an exemplary embodiment.

FIG. 6A is a side view of the speed control assembly of FIG. 5.

FIG. 6B is a front view of a wall of the speed control assembly of FIG. 6A.

FIG. 7A is a sectional view of a speed control assembly according to another exemplary embodiment.

FIG. 7B is a side view of an end cap for the speed control assembly of FIG. 7A.

FIG. 8 is a schematic diagram of a pressure washer according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.
Referring to FIG. 1, a pressure washer 110 includes an internal combustion engine 112 and a water pump 114. The engine 112 and the water pump 114 are mounted to a support structure 116, which includes wheels 118, a handle 120, a console 122, and a base plate 124. The internal combustion engine 112 is a small, four-stroke cycle engine with a vertical shaft (not shown). The engine 112 further includes a muffler 126, an air intake 128, and a spark plug 130 extending through a cylinder head 132. A recoil starter 134 for the engine 112 is integrated with a cover 136. The internal combustion engine 112 is mounted on top of the base plate 124, and the water pump 114 is mounted beneath the base plate 124. The water pump 114 shown in FIG. 1 is an axial cam water pump, which is a positive displacement pump having three pistons. The water pump 114 includes an inlet 238 (see FIG. 2) and an outlet 140, where the inlet 238 is designed to be coupled to a water source, such as a bibcock or faucet and the outlet is designed to be coupled to a pressure washer spray gun 142 via a high-pressure hose 144.
In some embodiments, a pressure washer may be powered by a diesel engine, an electric motor, a combustion engine with a horizontal shaft, or another form of a motor. In some embodiments, the water pump may be a centrifugal water pump, a triplex water pump, a duplex water pump, or another type of pump. The pump may be mounted on top of a base plate, on top of an engine, on a side of an engine, or otherwise mounted. Additionally, the concepts disclosed herein may be used with other types of power equipment, such as a leaf blower, a snow blower, a garden hose booster pump, or another type of power equipment that operates with a pressurized fluid (e.g., air, water, coolant, motor oil, etc.).
The spray gun 142, which is releasably mounted on the support structure 116, includes a biased trigger 146. The trigger 146 may be pulled to open a valve (not shown), permitting a flow of water through the spray gun 142. Releasing the trigger 146 stops the flow of water through the spray gun 142 by closing the valve. In some embodiments, the spray gun 142 has multiple flow-rate or spray settings, with some settings producing a tighter flow beam and other settings producing a broad spray. Still other embodiments use other forms of sprayers, such as automatic sprinklers.
Still referring to FIG. 1, a pressure-sensitive member in the form of a mechanical pressure-sensitive member 148 is coupled to the pump 114. The pressure-sensitive member 148 produces an output signal that is a function of water pressure within the pump 114. A communication line, in the form of a wire 150 according to an exemplary embodiment, extends from the pressure-sensitive member 148 and transmits an output signal. For example, the pressure-sensitive member 148 communicates with the engine 112 to control engine speed as a function of pressure in the pump 114. In some exemplary embodiments, the wire 150 directly links the pressure-sensitive member 148 to the engine 112. The wire 150 attaches directly to a governor spring (e.g., governor spring 420 as shown in FIG. 4) on the engine 112. The governor spring controls a throttle plate position (e.g., throttle plate 830 as shown schematically in FIG. 8), regulating the speed of the engine 112 as a function of pressure in the water pump 114.
Referring to FIG. 2, the water pump 114 has a housing 252 (i.e., pump head), the inlet 238, and the outlet 140. The inlet 238 includes a coupling 254 to attach a hose or pipe. The coupling 254 may be a threaded female coupling, a female quick-connect coupling, or some other form of coupling. According to an exemplary embodiment, a garden hose may be attached to the coupling 254, supplying water to the pump 114 through the inlet 238. From the inlet 238 the water is directed to a pumping mechanism. The pumping mechanism displaces a volume of the water, increasing pressure, hydraulic power, velocity, work energy, or otherwise driving the water.
The structure of the pumping mechanism varies depending upon particular embodiments. For example, the pump 114 has three pistons (not shown) slidable within piston chambers 256. The pistons are coupled to a power take-off of a motor or engine (e.g., combustion engine 112 as shown in FIG. 1), and the pistons run on two-stroke cycles, with an inlet stroke and a discharge stroke. In other embodiments, the pumping mechanism includes one, two, or four pistons. In still other embodiments, the pumping mechanism includes an axial cam that rotates to accelerate water injected near a center of the cam, and which is then ejected near a periphery of the cam. In other embodiments the pumping mechanism includes a rotor, an impeller, or a compressor. Still other embodiments include peristaltic pumps, scroll pumps, centrifugal pumps, gear pumps, and other types of pumps.
Following passage through the pumping mechanism, the water enters a discharge manifold 258 adjacent to piston ports 260 at a discharge end of the piston chambers 256. The discharge manifold 258 combines the water discharged from multiple piston ports 260. Adjacent to the discharge manifold 258, the pump 114 includes a trapped pressure unloader 262. The trapped pressure unloader 262 diverts the water into a bypass line (i.e., recirculation circuit) when the sprayer (e.g., spray gun 142 as shown in FIG. 1) of the pressure washer 110 is not actively spraying (i.e., recirculation mode), and a trapped body of water is held between the sprayer and the unloader 262. When the sprayer is spraying, water flows through the trapped pressure unloader 262 to the outlet 140 of the pump 114. The outlet 140 includes a coupling 264 to attach a hose or pipe. In some embodiments, the coupling 264 is a threaded male coupling, a male quick-connect coupling, or some other form of coupling. The hose or pipe then directs the water to the sprayer.
Referring to FIGS. 3A-3B, a trapped pressure unloader 310 is positioned adjacent to a pump discharge manifold (e.g., manifold 258 as shown in FIG. 2). The unloader 310 includes a biased check valve 312, a ball valve 314, and a pressure-sensitive member 316 (e.g., pressure transducer, pressure sensor, load cell, strain gauge coupled to pump wall, etc.). When a pressure washer is actively spraying, the unloader 310 forms a main flow path through the unloader 310 (see FIG. 3A, where arrows 318 indicate the direction of the water). Sufficient water pressure pushes the biased check valve 312 open (i.e., “through mode”).
When the pressure washer is not spraying, the unloader 310 forms a bypass flow path (see FIG. 3B, where arrows 320 indicate the direction of the water). The unloader 310 directs the water into a recirculation circuit (i.e., “bypass mode”). In the bypass mode, water within the unloader 310 is divided into an open bypass flow path (i.e., recirculation circuit, shown by arrows 320) and a trap line (shown by dashed lines 322). Pressure in the water of the trap line is directed along a conduit 324 that leads to a chamber 326 above the ball valve 314. Pressure in the chamber 326 opens the ball valve 314, engaging the recirculation circuit.
In a pressure washer water pump, such as the pump 114 (FIG. 2), water pressure in the discharge manifold 258 approximately matches water pressure in the trapped pressure unloader 262, in the bypass line when the bypass line is active. As such, a pressure-sensitive member, such as the pressure-sensitive member 148, may be coupled to the pump 114 in a variety of locations. Referring to FIG. 2, the pressure-sensitive member 148 is coupled to the discharge manifold 258. Referring to FIGS. 3A-3B, the pressure-sensitive member 316 is coupled to the trapped pressure unloader 310, as opposed to a discharge manifold. In still other embodiments, a pressure sensitive member is attached to a piston port, or other portions of the pressure washer. However, positioning the pressure-sensitive member to be able to sense the water pressure in the bypass line when the bypass line is active provides a wide pressure differential between pressures experienced when the pressure washer 110 spraying (i.e., through mode) versus those experienced when the pressure washer 110 is not spraying (i.e., bypass mode). For example, pressures experienced during the through mode may be greater than 1500 psi, such as 2500 psi. Pressures experienced during the bypass mode within the bypass line may be below 500 psi, such as 200 psi to 300 psi. As such, the pressure differential experienced by the pressure-sensitive member, between the through mode and the bypass mode, may exceed 1000 psi, as high as 2000 psi or more.
In FIGS. 2, 3A, and 3B, the pressure- sensitive members 148, 316 have similar structures. For example, the pressure-sensitive member 316 includes an elongate cylindrical housing 330, a plunger 332 (or piston) slidable within the housing 330, and a port 334 in fluid communication with water within the water pump (e.g., pump 114 as shown in FIG. 2). The plunger 332 is biased by a coil spring 336, and is coupled to a communication line 338. In some exemplary embodiments, the communication line 338 is a wire, such as a Bowden cable (i.e., wire core slidable within casing). FIG. 3A shows the pressure-sensitive member 316 in a first orientation in reaction to a high water pressure. FIG. 3B shows the pressure-sensitive member 316 in a second orientation in reaction to a lower water pressure.
Referring now to FIG. 4, an engine 410 may be used to drive a pressure washer pump (e.g., pump 114 as shown in FIG. 1). The engine includes a cover 412, an exhaust tube 414, a rocker cover 416, an air filter cover 418, and other engine components. A Bowden cable 422, which extends from a pressure-sensitive member (not shown) attached to a pressure washer water pump, and is coupled to the engine 410, proximate to a fuel system of the engine 410. The Bowden cable 422 includes an inner wire 424 and an outer casing 426, and is attached to a wall 428 on a side of the engine 410. The outer casing 426 of the Bowden cable 422 terminates at the wall 428, surrounded by an adjuster screw 430 (e.g., barrel adjuster) coupled to a locking nut 432. The adjuster screw 430 may be twisted to adjust tension on the inner wire 424 by displacing the outer casing 426 of the Bowden cable 422. The inner wire 424 of the Bowden cable 422 extends through the wall 428 and directly engages a governor spring 420. In some embodiments, the wall 428 is spaced apart from the governor spring 420 by a distance 434 that allows for sliding of a plunger (e.g., plunger 332 as shown in FIGS. 3A and 3B) within a pressure-sensitive member (e.g., pressure-sensitive member 316 as shown in FIGS. 3A and 3B) at another end of the Bowden cable. In some embodiments, the distance is at least an inch.
Referring to FIGS. 5, 6A, and 6B, an engine speed control assembly 510 includes a Bowden cable 512 directly attached to a governor spring 514, as opposed to a speed lever 516 (i.e., a throttle lever) or another intermediate mechanism. An outer casing 524 of the Bowden cable 512 is attached to a wall 520 with an adjustable screw 560 and a nut 562. Direct attachment may reduce costs and chances of malfunctions of the engine speed control assembly 510. According to an exemplary embodiment, an inner wire 518 of the Bowden cable 512 is guided through the wall 520. As shown in FIG. 6B, the wall 520 includes an aperture with an entry slot 522 through which the inner wire 518 of the Bowden cable 512 may be inserted. The slot 522 is too narrow to allow the outer casing 524 of the Bowden cable 512 to be inserted. An end 526 of the inner wire 518 includes a loop 528, or an eyelet, through which a hook 530 on the governor spring 514 is attached.
Tension in the inner wire 518 of the Bowden cable 512 is a function of the pressure in the pump (e.g., pump 114 as shown in FIG. 2), which changes in response to operation of the sprayer of the pressure washer. Tension in the inner wire 518 (e.g., pulling of the wire 518) increases tension in the governor spring 514, biasing a throttle plate (e.g., throttle plate 830 as schematically shown in FIG. 8) of the engine toward a full-open throttle position. Release of tension in the inner wire 518, decreases the tension in the governor spring 514, allowing a governor (e.g., speed-sensing device 826 as schematically shown in FIG. 8) to pull the throttle plate into the closed position. In some embodiments, the engine (e.g., engine 410 shown in FIG. 4) has at least two running speeds: idle and a governed speed that is greater than the idle speed. The Bowden cable 512 transmits signals of the pressure-sensitive member to the governor spring, such that the engine is set to an idle when the pressure-sensitive member detects a pressure below a threshold, corresponding to the pump being in the bypass mode. The engine is set to a normal operational speed (exceeding the idle speed) when the pressure-sensitive member detects a water pressure above the threshold, corresponding to the pump being in the through mode.
Referring to FIG. 5, speed lever 516 may coupled to the governor spring 514, such as through a hook 532. In other embodiments, a speed lever may be coupled a throttle plate without use of a governor spring (e.g., with a connecting bar, interlocking gears, etc.). As shown in the embodiment of FIG. 5, the speed lever 516 is not connected to the governor spring 514. The governor spring 514 is coupled directly to inner wire 518 of the Bowden cable 512 instead.
Referring to FIGS. 7A-7B, an assembly 710 is designed to relay communication signals from a pressure-sensitive member directed to the control of a throttle plate via a governor spring. The assembly 710 includes a Bowden cable 712 having an inner wire 714 and an outer casing 716. The Bowden cable 712 includes a first end coupled to an actuator responsive to signals from a pressure-sensitive member, and a second end coupled to a barrel adjuster 718 and a locking nut 720. The barrel adjuster 718 and the locking nut 720 are positioned adjacent to a first side 724 of a wall 722. The inner wire 714 of the Bowden cable 712 is guided through the wall 722 by a guide 726. On a second side 728 of the wall 722, the inner wire 714 extends through a spring 730 (e.g., a second spring relative to the spring 336) positioned within a chamber 732 formed by an assembly housing 748. The housing 748 guides the spring 730. In some embodiments, the housing 748 is supported or anchored by the guide 726, the wall 722, a second wall 744, or otherwise anchored. A first end 734 of the spring 730 is positioned adjacent to the wall 722 or on a support extending from the wall 722, such as a shoulder 736 of the housing 748 within the chamber 732. A second end 738 of the spring 730 is adjacent to an end cap 740 (e.g., annular cap), which is attached to the inner wire 714. Tension in the wire 714 is absorbed by the spring 730 because a flange 742 on the end cap 740 compresses the spring 730. The end cap 740 includes an eyelet 746 or other form of catch. A governor spring may be coupled to the inner wire 714 via the eyelet 746. The end cap 740 further includes a skirt 750 extending within the coils of the spring 730. The skirt 750 guides (i.e., pilots) the end cap 740, keeping the end cap 740 level as the spring 730 contracts with pull of the inner wire 714.
In some embodiments, the wall 722 and guide 726 provide sufficient support for the housing 748. The second wall 744 is not included in the assembly 710. In certain embodiments, an end cap is integral with the inner wire, or the inner wire has a loop integrally formed with the wire to engage the governor spring. In still other embodiments, the end cap has a catch that is a hook, releasable pliers, a rectangular loop, or another form of catch.
Referring now to FIG. 8, a pressure washer system 810 includes an engine 812. The engine 812 runs at an engine speed 814. A pump 818 is driven by the engine 812, increasing a water pressure 816. The pump 818 is coupled to a sprayer 822, and includes a trapped pressure unloader 824. When the sprayer 822 is actively spraying, the trapped pressure unloader 824 directs water to the sprayer 822. When the sprayer 822 is not spraying, the trapped pressure unloader 824 directs water to a recirculation circuit within the pump 818. Water that has passed through the trapped pressure unloader 824 is held in a trap line between the pump 818 and the sprayer 822. The water pressure 816 within the recirculation circuit when the sprayer 822 is not spraying is significantly lower than the water pressure passing through the unloader 824 when the sprayer 822 is spraying. Also, water pressure in the trap line when the sprayer 822 is not spraying is slightly greater than the water pressure passing through the unloader 824 when the sprayer 822 is spraying.
A speed-sensing device 826 (e.g., rotating flyweights) is coupled to the engine 812. In some embodiments the speed-sensing device 826 is a mechanical governor that communicates a signal to a throttle plate 830. The speed-sensing device 826 includes lever arms that are biased in a first position. Rotation of the crankshaft generates forces that move the lever arms to a second position. If the rate of rotation exceeds a desired engine speed, then the lever arms move past the second position. If the rate of rotation is less than the desired engine speed, then the lever arms do not reach the second position. Position of the lever arms is relayed to the throttle plate 830 by a mechanical linkage. An excessive rate of rotation causes the speed-sensing device 826 to close the throttle plate 830. A deficient rate of rotation causes the speed-sensing device 826 to open the throttle plate 830.
In other embodiments, an air vane governor (i.e., pneumatic governor) is used. The rate of rotation of the crankshaft is proportional to the force of air blown by the blower fan. Pneumatic forces of the air push a governor blade, which is coupled to a throttle plate. In still other embodiments, accelerometers or pressure sensors are used generate an electric signal that is a function of the rate of rotation. The electric signal is relayed to an actuator that adjusts the throttle plate accordingly. In other embodiments, other forms of governors are used to sense and control engine speed.
In some embodiments, the speed-sensing device 826 is offset or opposed by a governor spring 828. For example, increased rotation of the engine crankshaft (i.e., engine speed) may cause the speed-sensing device 826 to pull the throttle plate 830 toward a closed position. However tension in the governor spring 828 may resist the pull of the speed-sensing device 826, holding the throttle plate 830 in an opened position. Accordingly, greater tension in the governor spring 828 increases the magnitude of pull necessary by the speed-sensing device 826 to close the throttle plate 830. In some embodiments a speed lever 832 is coupled to the governor spring 828, allowing for manual adjustment of tension in the governor spring 828. According to an exemplary embodiment, a pressure-sensitive member 834 (e.g., pressure-sensitive member 316 as shown in FIGS. 3A and 3B) is also coupled to the governor spring 828.
In some embodiments, the pressure-sensitive member 834 is formed from mechanical components, such as a diaphragm coupled to a rod, where the rod converts the diaphragm position into a linear movement. Still other embodiments employ electrical sensors within the pressure-sensitive member 834, such as piezo-electric crystals that generate an electric signal proportional to pressure. In at least one embodiment, the pressure-sensitive member 834 may be electro-mechanical, including a biased sliding plunger with a magnetic end. The plunger is coupled to a Reed switch (e.g., a small, glass tube having a field-sensitive electric switch). As such, change in pressure within the pump 818 causes the plunger to move the magnetic end relative to the reed switch, generating an electric signal. The pressure-sensitive member 834 may have any of a broad range of configurations, sizes, and geometries.
Still referring to FIG. 8, the pressure-sensitive member 834 is coupled to the governor spring 828 via a communication line 836 (e.g., Bowden cable 422 shown in FIG. 4). In some embodiments, the communication line 836 is a tightly strung wire extending around a series of pulleys. In other embodiment, the communication line 836 is an electronic or a radio-frequency transmission. For example, a transmitter on the pressure-sensitive member 834 may produce a signal identifying the pressure within the pump 818, which is then received by a receiver coupled to a solenoid that adjusts tension in the governor spring 828 accordingly.
In some embodiments, pressure washer characteristics other than water pressure are sensed, such as water flow rate, water turbulence, flow direction, and other characteristics. The characteristics may be sensed directly, such as with a sensor engaged with the water flow. The characteristics may be sensed indirectly by coupling sensors to the structure of the pump 818. For example, in one embodiment a strain gage may be attached to the outside of a water pump discharge manifold. The strain gage detects a change in pressure inside the discharge manifold by sensing strain in the manifold structure. The strain gage then converts a strain measurement into an electric signal that is proportional to the pressure. Still other sensors and configurations may also be employed, such as vibrometers and accelerometers within a pressure washer spray gun.
In some embodiments, the pressure-sensitive member 834, which is attached to the water pump 818, is coupled directly to the throttle plate 830, not the governor spring 828. In other embodiments, the pressure-sensitive member 834 is coupled to a first throttle plate, and the speed-sensing device 826 is coupled to a second throttle plate. Each throttle plate is designed to open or close a flow of fuel and air to the combustion chamber of an engine. In still other embodiments, the pressure-sensitive member 834 may entirely take the place of the speed-sensing device 826 for adjusting engine speed as a function of engine output, where water pressure corresponds to engine speed.
The construction and arrangements of the engine speed control for a pressure washer, as shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention.

Claims

1. A pressure washer, comprising:

a water pump;

a pressure-sensitive member coupled to the water pump,

a wire having a first end coupled to the pressure-sensitive member, wherein the pressure-sensitive member communicates a change in water pressure within the pump through the wire; and

an engine comprising:

a governor spring attached to the wire, wherein movement of the wire changes a tension of the governor spring; and

a throttle plate coupled to the governor spring, wherein the governor spring biases the throttle plate.

2. The pressure washer of claim 1, wherein the wire is an inner wire of a Bowden cable that further comprises an outer casing.

3. The pressure washer of claim 2, wherein the pressure-sensitive member comprises a chamber and a plunger slidable with the chamber, and wherein the plunger slides in response to the change in pressure within the chamber.

4. The pressure washer of claim 3, wherein the wire is fastened to the plunger.

5. The pressure washer of claim 4, wherein the engine further comprises a wall with an aperture formed therein, wherein the inner wire of the Bowden cable extends through the aperture, and wherein the outer casing of the Bowden cable terminates on a first side of the wall.

6. The pressure washer of claim 5, wherein the inner wire extends through a housing on a second side of the wall, the housing containing a second spring, which surrounds the inner wire.

7. The pressure washer of claim 6, wherein the inner wire is coupled to a loop on an end thereof, and wherein the loop is fastened to the governor spring.

8. The pressure washer of claim 7, wherein the loop is integral with an annular cap having a flange, the flange positioned upon an end of the second spring.

9. The pressure washer of claim 8, wherein the annular cap further comprises a skirt extending from the flange and surrounded by the second spring, wherein the skirt pilots the annular cap as the second spring expands or contracts.

10. A pressure washer, comprising:

an internal combustion engine having a governor system comprising:

a speed-sensing device configured to detect the speed of the engine,

a throttle plate configured to move between a wide open throttle position and a closed position, the throttle plate controlling a flow of air and fuel for consumption by the engine,

a linkage between the speed-sensing device and the throttle plate, wherein the linkage adjusts the throttle plate in response to the speed of the engine, and

a governor spring biasing the throttle plate toward the wide open throttle position; and

a high-pressure water pump powered by the engine; and

a pressure-sensitive member coupled to the pump, wherein the pressure-sensitive member moves a wire in response to a change in water pressure within the pump, and wherein the wire is attached to and configured to load the governor spring.

11. The pressure washer of claim 10, wherein the wire is covered by and slidable within a casing, the wire and the casing together forming a Bowden cable.

12. The pressure washer of claim 11, wherein the wire comprises a catch on an end thereof, wherein the governor spring comprises a hook on an end thereof, and wherein the hook engages the catch.

13. The pressure washer of claim 12, wherein the engine further includes a wall having an aperture formed therein, and wherein the wire extends through the aperture and the casing terminates on a first side of the wall.

14. The pressure washer of claim 13, further comprising a locking nut and an adjuster screw surrounding the wire, the locking nut and the adjuster screw in series along the wire.

15. The pressure washer of claim 14, wherein the locking nut is adjacent to the first side of the wall and the adjuster screw is adjacent to the locking nut.

16. The pressure washer of claim 15, further comprising a guide extending through the aperture and surrounding the wire.

17. A pressure washer control system, comprising:

a water pump;

a pressure-sensitive member comprising:

a chamber coupled to the water pump, and

a plunger slidable with the chamber, wherein the plunger slides in response to a change in water pressure within the pump;

a wire having a first end coupled to the pressure-sensitive member, wherein the pressure-sensitive member adjusts tension in the wire in response to the change in water pressure within the pump; and

an engine comprising:

a governor spring attached to the wire, wherein adjustment of tension in the wire changes tension in the governor spring, and

18. The system of claim 17, wherein the water pump further comprises a trapped pressure unloader, and wherein the water pump is configured to operate in a through mode and a recirculation mode.

19. The system of claim 18, wherein when the pump is operating in the recirculation mode the trapped pressure unloader separates a flow of water passing therethrough into a recirculation circuit of water and a trapped body of water, wherein the chamber of the pressure-sensitive member is coupled to the recirculation circuit.

20. The system of claim 19, wherein when the pump is operating in the recirculation mode the wire moves the throttle plate to idle the engine.