The present invention relates to an air motor having ceramic valves and valve plates to enhance performance of the air motor. The ceramic valves and valve plates reduce sticking, better accommodate debris, and better resist wear than conventional metal or composite valves and valve plates.
In one embodiment, the invention provides an air motor comprising: a motive fluid inlet (335) adapted to receive a flow of motive fluid; a cylinder (615); a piston (620) within the cylinder (615), the piston (620) dividing the cylinder (615) into an upper chamber (635) above the piston (620) and a lower chamber (640) below the piston (620); a valve chamber (355) including a pilot chamber portion (515); a spool valve (360) shiftable between first and second positions, the spool valve (360) including a reduced diameter section (480) and an enlarged diameter section (485), the enlarged diameter section (485) being exposed to the pilot chamber portion (515); a ceramic D-valve plate (375) including a first D-valve port (455) communicating with the upper chamber (635), a second D-valve port (460) communicating with the lower chamber (640), and a D-valve exhaust port (465) communicating with atmosphere; a ceramic D-valve (370) having a flat surface surrounding a concave surface (520), the flat surface being in sliding contact with the D-valve plate (375) and the concave surface (520) facing the D-valve plate (375), the D-valve (370) being coupled via a lost motion interconnection (525) to the reduced diameter section (480) of the spool valve (360), the D-valve (370) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the D-valve (370) uncovers the first D-valve port (455) when the D-valve (370) is in the first position to introduce motive fluid into the upper chamber (635), the concave surface (520) of the D-valve (370) placing the second D-valve port (460) in communication with the D-valve exhaust port (465) to place the lower chamber (640) in communication with the atmosphere when the D-valve (370) is in the first position, wherein the D-valve (370) uncovers the second D-valve port (460) when the D-valve (370) is in the second position to introduce motive fluid into the lower chamber (640), the concave surface (520) of the D-valve (370) placing the first D-valve port (455) in communication with the D-valve exhaust port (465) to place the upper chamber (635) in communication with the atmosphere when the D-valve (370) is in the second position; a ceramic pilot valve plate (385) including a first pilot port (470) communicating with the pilot chamber portion (515) and a second pilot port (475) communicating with atmosphere; a ceramic pilot valve (380) having a flat surface surrounding a concave surface (530), the flat surface being in sliding contact with the pilot valve plate (385) and the concave surface (530) facing the pilot valve plate (385), the pilot valve (380) being coupled to the reduced diameter section (480) of the spool valve (360), the pilot valve (380) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the pilot valve (380) uncovers the first pilot port (470) when the pilot valve (380) is in the first position to introduce motive fluid into the pilot chamber (515), and wherein the concave surface (530) of the pilot valve (380) places the first and second pilot ports (470, 475) in communication with each other to place the pilot chamber (515) in communication with the atmosphere when the pilot valve (380) is in the second position, wherein introduction of motive fluid into the pilot chamber (515) shifts the spool valve (360) to the first position, wherein exposing the pilot chamber (515) to atmosphere facilitates shifting the spool valve (360) to the second position; an actuation rod (625) having a first end (650) and a second end (660) opposite the first end (650), the first end (650) being interconnected by way of a lost motion connection (490, 655) to the spool valve (360), the second end (660) being interconnected by way of a lost motion connection (725, 665) to the piston (620), such that upward movement of the piston (620) assists the spool valve (360) moving from the second position toward the first position, and such that downward movement of the piston (620) assists the spool valve (360) moving from the first position to the second position; and an output rod (710) interconnected for reciprocal movement with the piston (620) and adapted to perform work.
In another embodiment, the invention provides a pump assembly comprising: a motive fluid inlet (335) adapted to receive a flow of motive fluid; a cylinder (615); a piston (620) within the cylinder (615), the piston (620) dividing the cylinder (615) into an upper chamber (635) above the piston (620) and a lower chamber (640) below the piston (620); a valve chamber (355) including a pilot chamber portion (515); a spool valve (360) shiftable between first and second positions, the spool valve (360) including a reduced diameter section (480) and an enlarged diameter section (485), the enlarged diameter section (485) being exposed to the pilot chamber portion (515); a ceramic D-valve plate (375) including a first D-valve port (455) communicating with the upper chamber (635), a second D-valve port (460) communicating with the lower chamber (640), and a D-valve exhaust port (465) communicating with atmosphere; a ceramic D-valve (370) having a flat surface surrounding a concave surface (520), the flat surface being in sliding contact with the D-valve plate (375) and the concave surface (520) facing the D-valve plate (375), the D-valve (370) being coupled via a lost motion interconnection (525) to the reduced diameter section (480) of the spool valve (360), the D-valve (370) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the D-valve (370) uncovers the first D-valve port (455) when the D-valve (370) is in the first position to introduce motive fluid into the upper chamber (635), the concave surface (520) of the D-valve (370) placing the second D-valve port (460) in communication with the D-valve exhaust port (465) to place the lower chamber (640) in communication with the atmosphere when the D-valve (370) is in the first position, wherein the D-valve (370) uncovers the second D-valve port (460) when the D-valve (370) is in the second position to introduce motive fluid into the lower chamber (640), the concave surface (520) of the D-valve (370) placing the first D-valve port (455) in communication with the D-valve exhaust port (465) to place the upper chamber (635) in communication with the atmosphere when the D-valve (370) is in the second position; a ceramic pilot valve plate (385) including a first pilot port (470) communicating with the pilot chamber portion (515) and a second pilot port (475) communicating with atmosphere; a ceramic pilot valve (380) having a flat surface surrounding a concave surface (530), the flat surface being in sliding contact with the pilot valve plate (385) and the concave surface (530) facing the pilot valve plate (385), the pilot valve (380) being coupled to the reduced diameter section (480) of the spool valve (360), the pilot valve (380) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the pilot valve (380) uncovers the first pilot port (470) when the pilot valve (380) is in the first position to introduce motive fluid into the pilot chamber (515), and wherein the concave surface (530) of the pilot valve (380) places the first and second pilot ports (470, 475) in communication with each other to place the pilot chamber (515) in communication with the atmosphere when the pilot valve (380) is in the second position, wherein introduction of motive fluid into the pilot chamber (515) shifts the spool valve (360) to the first position, wherein exposing the pilot chamber (515) to atmosphere facilitates shifting the spool valve (360) to the second position; an actuation rod (625) having a first end (650) and a second end (660) opposite the first end (650), the first end (650) being interconnected by way of a lost motion connection (490, 655) to the spool valve (360), the second end (660) being interconnected by way of a lost motion connection (725, 665) to the piston (620), such that upward movement of the piston (620) assists the spool valve (360) moving from the second position toward the first position, and such that downward movement of the piston (620) assists the spool valve (360) moving from the first position to the second position; an output rod (710) interconnected for reciprocal movement with the piston (620); and a piston pump (120) including a pump cylinder (170), an outlet (175), and a one-way valve supported for reciprocation within the pump cylinder (170) and operable to move fluid from below the one-way valve toward the outlet (175), the one-way valve being interconnected with the output rod (710) to cause reciprocation of the one-way valve to move a fluid to be pumped from within the cylinder (170) out the outlet (175) to a desired destination.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
A supply of motive fluid 145 communicates with the top and bottom end of each of the first and second rams 130 via ram hoses 150. In this disclosure, the term “motive fluid” means any fluid that is used to perform work. Motive fluid includes but is not limited to compressed air. A control handle 155 on the supply of motive fluid 145 is used to direct motive fluid to either the bottom end of the rams 130 or the top end of the rams 130, to respectively raise and lower the air motor 125 and piston pump 120 with respect to the base plate 135. Motive fluid is provided to the air motor 125 from the supply of motive fluid 145 via a motor hose 160. The air motor 125 operates under the influence of the motive fluid to operate the piston pump 120.
The piston pump 120 includes a wiper assembly 165, a pump cylinder 170, and an outlet 175. In operation, the rams 130 are raised such that the wiper assembly 165 is lifted a sufficient distance off the base plate 135 to accommodate a container of fluid to be pumped. The wiper assembly 165 is sized to fit within the container of fluid (e.g., a 5-gallon bucket, a barrel, or other container). When it is time to pump the fluid out of the container, the rams 130 are permitted to lower under the influence of gravity or are actively lowered by motive fluid being supplied to the tops of the rams 130. As the rams 130 are lowered, the wiper assembly 165 is pushed down into the container, with the wiper 165 pushing down on the fluid to be pumped. This feeds the fluid to be pumped into the pump cylinder 170.
At the same time as the rams 130 are lowered, motive fluid is supplied to the air motor 125 and the air motor 125 drives operation (i.e., reciprocation) of the piston pump 120. Within the pump cylinder 170, a one-way valve reciprocates under the influence of the air motor 125 to force fluid up to the outlet 175. From the outlet 175, the fluid to be pumped is directed by hoses or other conduits to a desired destination. Once the wiper 165 has bottomed out in the container, or it is otherwise desired to raise the wiper 165 out of the container, the supply of motive fluid 145 provides motive fluid into the container under the wiper 165 by way of a hose 180. This supply of motive fluid to the container permits the wiper 165 to be extracted from the container without creating a vacuum in the container that might lift the container.
With reference to
A valve chamber 355 is defined within the valve housing 310 between the manifold cover 315 and the pilot cover 325. Within the valve chamber 355 is a valve assembly, which includes a spool valve 360, a D-valve 370, a D-valve plate 375, a pilot valve 380, and a pilot valve plate 385. The spool valve 360 actually an assembly of parts, some of which will be described in more detail below. The spool valve 360 is generally centered within the valve chamber 355. The D-valve 370 and D-valve plate 375 are on the manifold side 340 of the valve housing 310, and the pilot valve 380 and pilot valve plate 385 are on the pilot side 345 of the valve housing 310.
Turning now to
The D-valve plate 375 includes a first D-valve port 455, a second D-valve port 460, and a D-valve exhaust port 465 between the first and second ports 455, 460. The first D-valve port 455, second D-valve port 460, and D-valve exhaust port 465 of the D-valve plate 375 register with the upper chamber port 410, lower chamber port 415, and the manifold exhaust port 420, respectively, in the manifold cover 315. The pilot valve plate 385 includes a first pilot port 470 and a second pilot port 475. The two-way pilot conduit 440 and pilot exhaust conduit 445 register with the first pilot port 470 and second pilot port 475, respectively.
The spool valve 360 includes an upper portion with a reduced-diameter section 480, a lower portion with an enlarged-diameter section 485, and a cup 487 in which the enlarged-diameter section 485 reciprocates. The enlarged-diameter section 485 includes a blind bore 490. A cover 495 secured across the opening of the blind bore 490 and held in place with a snap ring. A cup seal 510 on the outside of the enlarged-diameter section 485 creates a seal between the spool valve 360 and the valve housing 310. The portion of the valve chamber 355 below the cup seal 510 and outside of the cup 487 defines a pilot chamber 515 Immediately below the cup seal 510 is a vent bushing 517 which communicates between the inside of the cup 487 and the dedicated exhaust conduit 452. As a result, the inside of the cup 487 is constantly in communication with atmosphere through the vent bushing, dedicated exhaust conduit 452, and pilot exhaust conduit 445. This accommodates displaced and sucked in air above the head of the enlarged diameter section 485 during reciprocating movement of the spool valve 360. The two-way pilot conduit 440 communicates with the pilot chamber 515 below the vent bushing 517.
The D-valve 370 and pilot valve 380 are captured within a the reduced-diameter section 480 of the spool valve 360. As a result, the D-valve 370 and pilot valve 380 are coupled for reciprocation with the spool valve 360. The D-valve 370 includes a flat surface which abuts against and slides with respect to the D-valve plate 375. The D-valve 370 includes an arcuate, concave surface 520 that opens toward the D-valve plate 375. The flat surface of the D-valve surrounds the concave surface 520. The D-valve includes cut-outs 525 at the top and bottom which cause lost motion between the D-valve and the spool valve 360. The pilot valve 380 fits tightly within the reduced-diameter section 480 of the spool valve 360 so there is no lost motion. The pilot valve 380 includes an concave surface 530 that faces the pilot valve plate 385, and the pilot valve 380 includes a flat surface that surrounds the concave surface 530 and slides against the pilot valve plate 385.
Referring again to
With continued reference to
As illustrated in
The base 715 includes a base port 810 into which the lower end of the long drop tube 430 is received. The base port 810 places the lower chamber port 415 and long drop tube 430 in fluid communication with the lower chamber 640.
A cycle of operation of the valve assembly will now be described with reference to
The D-valve is pulled down by the spool valve 360. The upper chamber 635 is vented to atmosphere through the top plate port 648, the short drop tube 425, the upper chamber port 410, the first D-valve port 455, the concave surface 520 of the D-valve 370, the D-valve exhaust port 465, the manifold exhaust port 420, and the muffler 435. At the same time, the D-valve has uncovered the second D-valve port 460, such that motive fluid flows out of the valve chamber 355, through the second D-valve port 460, through the lower chamber port 415, through the long drop tube 430, through the base port 810, and into the lower chamber 640. As a result of this valve positioning, the piston 620 rises, which causes the actuation rod 625 to rise.
In
The pilot valve covers the second pilot port 475 and pilot exhaust conduit 445. The lower chamber 640 is vented to atmosphere through the base port 810, the long drop tube 430, the lower chamber port 415, the second D-valve port 460, the concave surface 520 of the D-valve 370, the D-valve exhaust port 465, the manifold exhaust port 420, and the muffler 435. At the same time, the D-valve has uncovered the first D-valve port 455, such that motive fluid flows out of the valve chamber 355, through the first D-valve port 455, through the upper chamber port 410, through the short drop tube 425, through the top plate port 648, and into the upper chamber 635. As a result of this valve positioning, the piston 620 lowers, which causes the actuation rod 625 to lower.
The portion of the valve chamber 355 above the spool valve 360 is at motive fluid pressure, and the portion of the valve chamber 355 below the spool valve 360 (i.e., the pilot chamber 515) is at atmospheric pressure. As a result, the spool valve 360 is pushed down from the position in
In
In
In
In
In
With reference now to
In contrast to ceramics, metal and composite materials will erode relatively quickly in a dirty air environment. Additionally, due to the surface finishes required of metals and composites to obtain a pneumatic seal, staking forces can arise between the metal or composite valves and plates that are excessive. The staking forces can give rise to inefficiencies of the air motor. The air motor must deliver sufficient actuation force (i.e., piston size for a given motive fluid flow and pressure) to overcome friction between parts such as valves and valve plates. Because the use of ceramics may reduce friction between the valves and valve plates, savings and operating economies may be achieved by reducing piston size and motive fluid consumption, compared to air motors that deliver the same output but have metal or composite valves and valve plates.
Thus, the invention provides, among other things, an air motor for a piston pump assembly, the air motor including ceramic valves and valve plates. Various features and advantages of the invention are set forth in the following claims.
This application claims priority to U.S. Provisional Patent Application No. 61/299,828, filed Jan. 29, 2010, the entire contents of which are herein incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US11/22960 | 1/28/2011 | WO | 00 | 7/24/2012 |
Number | Date | Country | |
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61299828 | Jan 2010 | US |