US5086975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressure washer with spring-less outlet to inlet bypass
Assignee: Mcculloch Corp
•
Filing: 1990-12-26
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Granted: 1992-02-11
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Expires: 2010-12-26
Abstract
Abstract A pressure washer for delivering a liquid under high pressure has an inlet conduit connected to a liquid supply and an outlet conduit connected to a spray nozzle which can be operated to control the delivery of liquid through the nozzle. A bypass conduit enables recirculation of the liquid from the outlet conduit to the inlet conduit. A bypass system, disposed between the outlet conduit and the bypass conduit, includes a shuttle valve which moves between first and second positions at which it respectively blocks or opens the liquid path from the outlet conduit to the bypass conduit. The shuttle includes an axial passage from its inlet to its outlet side which passage has a narrowed jet outlet such that, when the liquid flows through the spray nozzle and the outlet conduit, the pressure drop across the shuttle moves the shuttle to the first position, while when the flow out the spray nozzle is stopped or significantly blocked, pressure on the side of the shuttle facing the spray nozzle rises to the level at the inlet side of the shuttle, which moves the shuttle to unblock the bypass conduit. A seal arrangement in the pressure washer pump comprises a pair of seals between each piston and cylinder wall of the pump. One of the seals pivots in response to side to side wobbling of the piston while maintaining the seal.
Inventors
- 👤 Clive R. Paige
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 23:27
CPC Classifications
F; F04; F04B; F04B49/00; F04B49/22; F04B49/24; B; B08; B08B; B08B3/00; B08B3/02; B08B3/026; B08B2203/00; B08B2203/02; B08B2203/0205; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86718; Y10T137/86759; Y10T137/86791; Y10T137/86799
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
419 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; and a liquid bypass system associated with the bypass conduit for selectively closing and opening the bypass conduit to flow of liquid through the bypass conduit, the bypass system including: a bypass chamber in liquid communication with the bypass conduit, the bypass chamber having a chamber inlet in fluid communication with the outlet conduit for receiving liquid from the outlet conduit and having a chamber outlet for delivering liquid to the outlet conduit; a shuttle so shaped and so movable in the bypass chamber between a first position in which the shuttle blocks fluid communication between the bypass chamber and the bypass conduit and a second position which permits fluid communication between the bypass chamber and the bypass conduit; the shuttle having a first surface area in the bypass chamber which is exposed to liquid pressure at the chamber inlet and having a second surface area in the bypass chamber which is exposed to liquid pressure in the chamber outlet; a liquid passage which extends through the shuttle from the first to the second surface areas of the shuttle; the liquid passage being narrowed in cross-section sufficiently for producing a pressure drop in the bypass chamber across the shuttle from the first to the second surface areas when liquid is passing through the liquid passage; the first and second surface areas of the shuttle are so constructed and dimensioned and the liquid passage is of sufficiently narrowed cross-section for producing a sufficient pressure drop that the shuttle becomes disposed in the first position when liquid is exiting from the spray nozzle while liquid is passing through the liquid passage for causing the liquid pressure at the chamber inlet to be greater than the liquid pressure at the chamber outlet by a predetermined amount, and otherwise the shuttle is moved, by the liquid pressures at the chamber inlet and the chamber outlet, toward the second position.
Claim 2
Dependent Claim
419 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; and a liquid bypass system associated with the bypass conduit for selectively closing and opening the bypass conduit to flow of liquid through the bypass conduit, the bypass system including: a bypass chamber in liquid communication with the bypass conduit, the bypass chamber having a chamber inlet in fluid communication with the outlet conduit for receiving liquid from the outlet conduit and having a chamber outlet for delivering liquid to the outlet conduit; a shuttle so shaped and so movable in the bypass chamber between a first position in which the shuttle blocks fluid communication between the bypass chamber and the bypass conduit and a second position which permits fluid communication between the bypass chamber and the bypass conduit; the shuttle having a first surface area in the bypass chamber which is exposed to liquid pressure at the chamber inlet and having a second surface area in the bypass chamber which is exposed to liquid pressure in the chamber outlet; a liquid passage which extends through the shuttle from the first to the second surface areas of the shuttle; the liquid passage being narrowed in cross-section sufficiently for producing a pressure drop in the bypass chamber across the shuttle from the first to the second surface areas when liquid is passing through the liquid passage; the first and second surface areas of the shuttle are so constructed and dimensioned and the liquid passage is of sufficiently narrowed cross-section for producing a sufficient pressure drop that the shuttle becomes disposed in the first position when liquid is exiting from the spray nozzle while liquid is passing through the liquid passage for causing the liquid pressure at the chamber inlet to be greater than the liquid pressure at the chamber outlet by a predetermined amount, and otherwise the shuttle is moved, by the liquid pressures at the chamber inlet and the chamber outlet, toward the second position.
Claim 3
Dependent Claim
31 words
The pressure washer of claim 2, wherein the shuttle has an axis along which the shuttle moves in the bypass chamber, and the liquid channel passes generally axially through the shuttle.
Claim 4
Dependent Claim
14 words
The pressure washer of claim 2, wherein the shuttle has a substantially circular cross-section.
Claim 5
Dependent Claim
106 words
The pressure washer of claim 2, further comprising first and second seals disposed axially spaced apart and extending circumferentially around the shuttle, the first seal being so placed with respect to the chamber inlet and the bypass conduit and the bypass chamber being so shaped and dimensioned as to seal the chamber inlet from the bypass conduit in the first position of the shuttle; and the second seal being so placed with respect to the chamber inlet and the bypass conduit and the bypass chamber being so shaped and dimensioned as to seal the chamber outlet from the bypass conduit in all positions of the shuttle.
Claim 6
Dependent Claim
125 words
The pressure washer of claim 4, wherein the bypass chamber has first, second and third axially extending and cross-sectionally differently sized axial regions; the first region being toward the chamber inlet and having a larger cross-section, the second region being toward the chamber outlet and having an intermediate cross-section, and the third region having a smaller cross-section and being disposed between the first and the second regions; the first seal extending around a portion of the shuttle which is movable between the first and third regions of the chamber, and the second seal extending around another portion of the shuttle which places the second seal at all times in sealing and sliding contact with a wall of the bypass chamber which defines the second region.
Claim 7
Dependent Claim
44 words
The pressure washer of claim 5, wherein the first seal has the cross-section of the third region of the bypass chamber so that the first seal is in sealing and sliding contact with a wall of the bypass chamber which defines the third region.
Claim 8
Dependent Claim
21 words
The pressure washer of claim 6, wherein the second seal has the cross-section of the second region of the bypass chamber.
Claim 9
Dependent Claim
19 words
The pressure washer of claim 5, wherein the bypass conduit meets the bypass chamber in the third region thereof.
Claim 10
Dependent Claim
111 words
The pressure washer of claim 8, wherein the first position of the shuttle places the first seal in contact with a wall of the bypass chamber which defines the third region and the third region is so placed that the first seal blocks liquid communication from the bypass chamber to the bypass conduit when the shuttle is in the first position; and the second position of the shuttle places the first seal such that it is radially spaced from a wall of the bypass chamber defining the first region of the bypass chamber and is spaced in a manner for permitting liquid flow from the bypass chamber to the bypass conduit.
Claim 11
Dependent Claim
45 words
The pressure washer of claim 4, wherein the liquid passage includes an upstream portion that is toward the first surface area and a downstream portion that is narrowed in cross-section and is in the region of the passage that is toward the second surface area.
Claim 12
Dependent Claim
32 words
The pressure washer of claim 4, further comprising a further liquid conduit opening into the bypass chamber at the third region and effective for introducing into the bypass chamber an additional liquid.
Claim 13
Dependent Claim
36 words
The pressure washer of claim 11, wherein the further liquid conduit is disposed at a location in the third region which is between the chamber outlet and the second seal, in all positions of the shuttle.
Claim 14
Dependent Claim
25 words
The pressure washer of claim 12, further comprising a one-way valve for enabling fluid to flow unidirectionally through the further liquid conduit into the chamber.
Claim 15
Dependent Claim
25 words
The pressure washer of claim 2, wherein the bypass chamber is defined by a neck which extends from a housing associated with the pumping means.
Claim 16
Dependent Claim
22 words
The pressure washer of claim 14, wherein the neck comprises means for securing thereto a hose coupling associated with the spray nozzle.
Claim 17
Dependent Claim
134 words
The pressure washer of claim 2, wherein the pump comprises: a cylinder and a piston reciprocable within the cylinder, the piston having a peripheral wall and a cross-sectional size which is smaller than the cross-section of the cylinder providing a radial clearance between the cylinder and the piston; an annularly extending notch in the cylinder; a first piston seal in the notch and a second piston seal extending between the first seal and the peripheral wall of the piston, the second piston seal being partially disposed in the notch, the first and second piston seals being effective to enable the piston to wobble relative to an axis of the cylinder while maintaining a liquid seal between the first and second piston seals and between the second piston seal and the wall of the piston.
Claim 18
Dependent Claim
23 words
The pressure washer of claim 16, wherein the piston further comprises a cover around the piston, which comprises the wall of the piston.
Claim 19
Dependent Claim
23 words
The pressure washer of claim 17, further comprising a further sealing means disposed between the cover and the piston covered by the cover.
Claim 20
Dependent Claim
35 words
The pressure washer of claim 17, further comprising a seal support disposed adjacent the first and second piston seals in a manner which is effective to retain the first and second seals in the notch.
Claim 21
Dependent Claim
27 words
The pressure washer of claim 16, wherein the pump comprises a plurality of the cylinders and a respective one of the pistons in each of the cylinders.
Claim 22
Dependent Claim
45 words
The pressure washer of claim 1, wherein the liquid passage includes an upstream portion that is toward the first surface area and a downstream portion that is narrowed in cross-section and is in the region of the passage that is toward the second surface area.
Claim 23
Dependent Claim
229 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump means connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; a cylinder and a piston reciprocable within the cylinder, the piston having a peripheral wall and a cross-sectional size which is smaller than the cross-section of the cylinder providing a clearance between the cylinder and the piston; an annularly extending notch in the cylinder; a first piston seal in the notch and a second piston seal extending between the first piston seal and the peripheral wall of the piston, the second piston seal being partially disposed in the notch, the first and second piston seals being effective to enable the piston to wobble relative to an axis of the cylinder while maintaining a liquid seal between the first and second piston seals and between the second piston seals and the wall of the piston.
Claim 24
Dependent Claim
229 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump means connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; a cylinder and a piston reciprocable within the cylinder, the piston having a peripheral wall and a cross-sectional size which is smaller than the cross-section of the cylinder providing a clearance between the cylinder and the piston; an annularly extending notch in the cylinder; a first piston seal in the notch and a second piston seal extending between the first piston seal and the peripheral wall of the piston, the second piston seal being partially disposed in the notch, the first and second piston seals being effective to enable the piston to wobble relative to an axis of the cylinder while maintaining a liquid seal between the first and second piston seals and between the second piston seals and the wall of the piston.
Claim 25
Dependent Claim
431 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; and a liquid bypass system associated with the bypass conduit for selectively closing and opening the bypass conduit to flow of liquid through the bypass conduit, the bypass system including a bypass chamber, in liquid communication with the bypass conduit, and having a chamber inlet in fluid communication with the outlet conduit for receiving liquid from the outlet conduit and a chamber outlet for delivering liquid to the outlet conduit; a shuttle in and movable axially along the bypass chamber; the shuttle having an inlet side facing toward the entrance of liquid into the bypass chamber and having an outlet side facing toward the exit of liquid from the bypass chamber into the outlet conduit; the shuttle being so shaped and being movable in the bypass chamber between a first position in which the shuttle blocks fluid communication between the bypass chamber and the bypass conduit and a second position which permits fluid communication between the bypass chamber and the bypass conduit; the shuttle and the bypass chamber being sized so that the surface area of the shuttle inlet side is smaller than the surface area of the shuttle outlet side, for normally urging the shuttle to the second position when the pressure in the bypass chamber at the outlet side of the shuttle approaches the pressure in the bypass chamber at the inlet side of the shuttle; a liquid passage through the shuttle from the inlet side to the outlet side, the passage including a narrowed region for defining a pressure drop across the shuttle when liquid flows from the spray nozzle and through the outlet conduit, and the surface areas of the inlet and outlet sides being so sized and the narrowed region of the liquid passage being of such cross-section that the pressure drop reduces the pressure at the outlet side of the shuttle as to cause the pressure at the inlet side of the shuttle to move the shuttle to the first position.
Claim 26
Dependent Claim
431 words
A pressure washer for delivering liquid under pressure, the pressure washer comprising: a spray nozzle for spraying liquid; an outlet conduit connected for delivering liquid to the spray nozzle; an inlet conduit for receiving liquid from a liquid supply; a pump connected between the inlet conduit and the outlet conduit and effective for pumping liquid from the inlet conduit to the outlet conduit; actuation means connected with the spray nozzle for selectively permitting or blocking exit from the spray nozzle of liquid pumped by the pump; a bypass conduit connected between the inlet conduit and the outlet conduit and in parallel with the pump; and a liquid bypass system associated with the bypass conduit for selectively closing and opening the bypass conduit to flow of liquid through the bypass conduit, the bypass system including a bypass chamber, in liquid communication with the bypass conduit, and having a chamber inlet in fluid communication with the outlet conduit for receiving liquid from the outlet conduit and a chamber outlet for delivering liquid to the outlet conduit; a shuttle in and movable axially along the bypass chamber; the shuttle having an inlet side facing toward the entrance of liquid into the bypass chamber and having an outlet side facing toward the exit of liquid from the bypass chamber into the outlet conduit; the shuttle being so shaped and being movable in the bypass chamber between a first position in which the shuttle blocks fluid communication between the bypass chamber and the bypass conduit and a second position which permits fluid communication between the bypass chamber and the bypass conduit; the shuttle and the bypass chamber being sized so that the surface area of the shuttle inlet side is smaller than the surface area of the shuttle outlet side, for normally urging the shuttle to the second position when the pressure in the bypass chamber at the outlet side of the shuttle approaches the pressure in the bypass chamber at the inlet side of the shuttle; a liquid passage through the shuttle from the inlet side to the outlet side, the passage including a narrowed region for defining a pressure drop across the shuttle when liquid flows from the spray nozzle and through the outlet conduit, and the surface areas of the inlet and outlet sides being so sized and the narrowed region of the liquid passage being of such cross-section that the pressure drop reduces the pressure at the outlet side of the shuttle as to cause the pressure at the inlet side of the shuttle to move the shuttle to the first position.
Claim 27
Dependent Claim
106 words
The pressure washer of claim 23, further comprising first and second seals disposed axially spaced apart and extending circumferentially around the shuttle, the first seal being so placed with respect to the chamber inlet and the bypass conduit and the bypass chamber being so shaped and dimensioned as to seal the chamber inlet from the bypass conduit in the first position of the shuttle; and the second seal being so placed with respect to the chamber inlet and the bypass conduit and the bypass chamber being so shaped and dimensioned as to seal the chamber outlet from the bypass conduit in all positions of the shuttle.
Claim 28
Dependent Claim
45 words
The pressure washer of claim 23, wherein the liquid passage includes an upstream portion that is toward the first surface area and a downstream portion that is narrowed in cross-section and is in the region of the passage that is toward the second surface area.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-10 | 1995-08-12 | 1996-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-10 | 1999-08-12 | 2000-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-10 | 2003-08-12 | 2004-02-11 | $7700.00 | Window Closed / Lapsed |