U.S. patent application number 12/553904 was filed with the patent office on 2009-12-24 for engine speed control for pressure washer.
This patent application is currently assigned to Briggs & Stratton Corporation. Invention is credited to Richard J. Gilpatrick.
Application Number | 20090317262 12/553904 |
Document ID | / |
Family ID | 41431488 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090317262 |
Kind Code |
A1 |
Gilpatrick; Richard J. |
December 24, 2009 |
ENGINE SPEED CONTROL FOR PRESSURE WASHER
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.
Inventors: |
Gilpatrick; Richard J.;
(Whitewater, WI) |
Correspondence
Address: |
Foley & Lardner LLP
777 East Wisconsin Avenue
Milwaukee
WI
53202-5306
US
|
Assignee: |
Briggs & Stratton
Corporation
|
Family ID: |
41431488 |
Appl. No.: |
12/553904 |
Filed: |
September 3, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12436656 |
May 6, 2009 |
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12553904 |
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11729692 |
Mar 29, 2007 |
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12436656 |
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60831330 |
Jul 17, 2006 |
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Current U.S.
Class: |
417/34 |
Current CPC
Class: |
F02D 29/04 20130101;
F02B 63/02 20130101; F04B 2205/05 20130101; B08B 3/026 20130101;
F04B 17/05 20130101; F02D 11/04 20130101; F04B 49/20 20130101 |
Class at
Publication: |
417/34 |
International
Class: |
F04B 49/20 20060101
F04B049/20 |
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 a throttle plate coupled to the governor
spring, wherein the governor spring biases the throttle plate.
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.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] 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
[0002] 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.
[0003] 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
[0004] 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.
[0005] 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.
[0006] 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.
[0007] Alternative exemplary embodiments relate to other features
and combinations of features as may be generally recited in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0008] 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:
[0009] FIG. 1 is a perspective view of a pressure washer according
to an exemplary embodiment.
[0010] FIG. 2 is a perspective view of a water pump of the pressure
washer of FIG. 1.
[0011] FIG. 3A is a sectional view of a trapped pressure unloader
in a first configuration according to an exemplary embodiment.
[0012] FIG. 3B is a sectional view of the trapped pressure unloader
of FIG. 3A in a second configuration.
[0013] FIG. 4 is a perspective view of an internal combustion
engine according to an exemplary embodiment.
[0014] FIG. 5 is a top view of a speed control assembly for a
pressure washer engine according to an exemplary embodiment.
[0015] FIG. 6A is a side view of the speed control assembly of FIG.
5.
[0016] FIG. 6B is a front view of a wall of the speed control
assembly of FIG. 6A.
[0017] FIG. 7A is a sectional view of a speed control assembly
according to another exemplary embodiment.
[0018] FIG. 7B is a side view of an end cap for the speed control
assembly of FIG. 7A.
[0019] FIG. 8 is a schematic diagram of a pressure washer according
to an exemplary embodiment.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0020] 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.
[0021] 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.
[0022] 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.).
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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").
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
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