CA1083462A - Shuttle valve - Google Patents
Shuttle valveInfo
- Publication number
- CA1083462A CA1083462A CA312,120A CA312120A CA1083462A CA 1083462 A CA1083462 A CA 1083462A CA 312120 A CA312120 A CA 312120A CA 1083462 A CA1083462 A CA 1083462A
- Authority
- CA
- Canada
- Prior art keywords
- valve
- valve member
- bore
- shuttle
- cross
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
- F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
- F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
- F16K11/065—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members
- F16K11/07—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with cylindrical slides
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0401—Valve members; Fluid interconnections therefor
- F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Multiple-Way Valves (AREA)
- Sliding Valves (AREA)
Abstract
SHUTTLE VALVE
Abstract of the Disclosure A shuttle valve comprising a valve body having an elongated bore and a plurality of ports in the side wall of the bore. A control port is located at each end of the bore surrounded by a valve seat. A shuttle valve member slides axially in the bore between the two valve seats to control the flow of fluid between the side wall ports. Bleed passageways provide high pressure fluid to chambers in the bore adjacent to the control port valve seats. A control device, such as a solenoid valve, alternatively connects one control port to a low pressure region and blocks the other, or vice versa, to cause the valve member to move between positions in which it engages one or the other control port valve seat. The ratio of the cross-sectional area of the valve member to the cross-sectional area of the valve seats is relatively small, i.e., the valve seats are of relatively large diameter although the control ports are small. The ratio of valve member area to valve seat area is in the range between 2 to 1 and 4 to 1, and is preferably no more than 3 to 1.
Abstract of the Disclosure A shuttle valve comprising a valve body having an elongated bore and a plurality of ports in the side wall of the bore. A control port is located at each end of the bore surrounded by a valve seat. A shuttle valve member slides axially in the bore between the two valve seats to control the flow of fluid between the side wall ports. Bleed passageways provide high pressure fluid to chambers in the bore adjacent to the control port valve seats. A control device, such as a solenoid valve, alternatively connects one control port to a low pressure region and blocks the other, or vice versa, to cause the valve member to move between positions in which it engages one or the other control port valve seat. The ratio of the cross-sectional area of the valve member to the cross-sectional area of the valve seats is relatively small, i.e., the valve seats are of relatively large diameter although the control ports are small. The ratio of valve member area to valve seat area is in the range between 2 to 1 and 4 to 1, and is preferably no more than 3 to 1.
Description
~334~2 This invention relates to shuttle valves, and more particularly to a shuttle valve having improved operating characteristics.
In a shuttle valve, a valve member, which may be in the form of a spool or two pistons joined by a xod, slides axially within an elongated bore in a valve body. The bore has a number of ports in its side wall which are typically connected to a source of pressurized fluid, a low pressure region, and a working `~
device of some kind, respectively. ~he valve member has two `
stable positions within the bore and controls communication between the ports, In one position of the valve member, the pressure port is connected to one of the working device ports and ~`~
the exhaust port is connected to another of the working device ports. In the other position of the shuttle valve member, the working device port which was connected to the pressure port is connected to the exhaust port and the working device port which was connected to the exhaust port is connected to the pressure port.
Movement of the shuttle valve member is controlled by pressurizing and exhausting two chambers located at the two ends of the bore in the valve body. More specifically, the two chambers are fed with pressurized fluid through bleed passageways.
A control port is provided at each end of the bore, and by means of a control valve one of the control ports is opened to a low pressure region while the other control port is blocked, or vice versa. As a result, the shuttle valve member is always pushed toward the end of the bore whose control port is open, and hence at a lower pressure, and away from the end of the bore whose control port is blocked, and hence at a higher pressure, A problem prese~ted by such valves i9 that when the con-trol valve, which may be manually operated, or remotely operated, such as by an electrical solenoid, changes its state to cause -1- ,: ~' . ', . ` . . : ` ' , ' , . . ''' ~ ' ' 46~
movement of the shuttle valve member, the pressurized chamber at one end of the bore slowly exhausts and the exhausted chamber slowly becomes pressurized. Thus, the shuttle valve member starts to move gradually from one end of the bore toward the o~her end, and completes the movement at a slow speed. Furthermore, a dashpot effect of the valve member in the chamber being slowly exhausted contributes to the slow and possibly unsteady movement of the shuttle valve member. This slow movement has a number of disadvantages, including the possibility that the valve member may actually get stuck at an intermediate poin~ in its movement due to the presence of dirt between the sliding valve member and the stationary seals within which it slides, or the valve member seizing within or sticking to those seals. Also, the quicker the movement of the shuttle valve member, the more positive and surer will be the response of the wor~ing device being controlled by the shuttle valve.
One way of solving the problem and providing more rapid movement of the shuttle valve member is to make the control ports at the ends of the bore very large, so t hat the chambers exhaust rapidly and become pressurized rapidly upon a change of state of the control valve. However, a disadvantage of this solution is that with larger control ports, and assuming a solenoid operated control valve, a larger solenoid requiring more electric power ~
to operate it would be necessary, or alternatively, with the same ~ ;
size solenoid only lower fluid pressures could be controlled. :
It is an object of the pre~ent invention to overcome these problems by providing a shuttle valve in which movement of the shuttle valve member is positive and rapid without employing con-trol ports of increased size.a This objective is accomplished by providing a valve seat around each control port which has a relatively large dia-meter, i,e., significantly larger than the cross-sectional size
In a shuttle valve, a valve member, which may be in the form of a spool or two pistons joined by a xod, slides axially within an elongated bore in a valve body. The bore has a number of ports in its side wall which are typically connected to a source of pressurized fluid, a low pressure region, and a working `~
device of some kind, respectively. ~he valve member has two `
stable positions within the bore and controls communication between the ports, In one position of the valve member, the pressure port is connected to one of the working device ports and ~`~
the exhaust port is connected to another of the working device ports. In the other position of the shuttle valve member, the working device port which was connected to the pressure port is connected to the exhaust port and the working device port which was connected to the exhaust port is connected to the pressure port.
Movement of the shuttle valve member is controlled by pressurizing and exhausting two chambers located at the two ends of the bore in the valve body. More specifically, the two chambers are fed with pressurized fluid through bleed passageways.
A control port is provided at each end of the bore, and by means of a control valve one of the control ports is opened to a low pressure region while the other control port is blocked, or vice versa. As a result, the shuttle valve member is always pushed toward the end of the bore whose control port is open, and hence at a lower pressure, and away from the end of the bore whose control port is blocked, and hence at a higher pressure, A problem prese~ted by such valves i9 that when the con-trol valve, which may be manually operated, or remotely operated, such as by an electrical solenoid, changes its state to cause -1- ,: ~' . ', . ` . . : ` ' , ' , . . ''' ~ ' ' 46~
movement of the shuttle valve member, the pressurized chamber at one end of the bore slowly exhausts and the exhausted chamber slowly becomes pressurized. Thus, the shuttle valve member starts to move gradually from one end of the bore toward the o~her end, and completes the movement at a slow speed. Furthermore, a dashpot effect of the valve member in the chamber being slowly exhausted contributes to the slow and possibly unsteady movement of the shuttle valve member. This slow movement has a number of disadvantages, including the possibility that the valve member may actually get stuck at an intermediate poin~ in its movement due to the presence of dirt between the sliding valve member and the stationary seals within which it slides, or the valve member seizing within or sticking to those seals. Also, the quicker the movement of the shuttle valve member, the more positive and surer will be the response of the wor~ing device being controlled by the shuttle valve.
One way of solving the problem and providing more rapid movement of the shuttle valve member is to make the control ports at the ends of the bore very large, so t hat the chambers exhaust rapidly and become pressurized rapidly upon a change of state of the control valve. However, a disadvantage of this solution is that with larger control ports, and assuming a solenoid operated control valve, a larger solenoid requiring more electric power ~
to operate it would be necessary, or alternatively, with the same ~ ;
size solenoid only lower fluid pressures could be controlled. :
It is an object of the pre~ent invention to overcome these problems by providing a shuttle valve in which movement of the shuttle valve member is positive and rapid without employing con-trol ports of increased size.a This objective is accomplished by providing a valve seat around each control port which has a relatively large dia-meter, i,e., significantly larger than the cross-sectional size
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of its respective control port, and such that there is a relatively small ratio between the cross-sectional sizes of the valve member and each valve seat, As a result of employing large valve seats, .:. .
one of which is engaged by an end of the shuttle valve member in each stable position of the valve member, upon a change of state of the control valve, the shuttle valve member does not begin to move until a significant proportion of the pressure in the chamber toward which the valve member will move is exhausted. The reason is that only a relatively small annular area at the end of the shuttle valve member outside the valve seat with which that end is in contact is exposed to the pressure in the chamber away from which the valve member will move. When the shuttle valve member does begin to move, the pressure in the chamber away from whi-ch it i~ moving is high and the pressure in the chamber being exhausted is re~atively low, so that the shuttle valve member is moved very rapidly by the relatively large pressure differential between the two chambers.
Additional objects, features, and explanation of the invention will be apparent from the following description in which reference is made to the accompanying drawings.
In the drawings:
Fig. 1 is a schematic longitudinal cross-sectional view of a spool-type shuttle valve according to the present invention;
Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. l;
Fig. 3 is a view similar to Fig. 1 showing the control valve and the shuttle valve member in an alternative position to that shown in Fig. l;
Fig. 4 is a cross-sectional view taken on line 4-4 of ;
Fig. 3; and Fig. 5 is a schematic longitudinal cross-sectional view of a piston-type shuttle valve according to the present invention.
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The shuttle valve chosen to illustrate the present invention, and shown in Figs. 1-4, includes a valve body 10 having an elongated bore 11. Bore 11 is closed at one end by an end plate 12 and at the other end by the valve body 13 of ~'~control means in the form of a solenoid operated valve 14. End plate 12 and valve body 13 are mounted on valve body 10 in a fluid tight `
manner by suitable fasteners (not shown). Body 10 is formed, in this example, with five ports 15, 16, 17, 18, and 19 in the side wall o~ bore 11. Projecting into bore 11 are six annular seals 20, formed for example of rubber or plastic, one seal being located between each two successive bores, and two seals being arranged beyond the extreme bores 15 and 19, respectively.
At each end, bore 11 is provided with an orifice. One of the orifices 23 is formed in end plate 12 and communicates with a passageway 24 formed in end plate 12 and body 10. The other end of passageway 24 terminates at the face of valve body D0 on which control valve body 13 is mounted~ The second orifice -25 is formed in control valve body 13. Orifice 23 is surrounded by an annular valve seat 26, and orifice 25 is surrounded by an annular valve seat 27, both valve seats~projecting into bore 11.
The end portion of bore 11 between valve seat 26 and the seal 20 to the left of port 15 defines a chamber 28, and the other end portion of bore 11 between valve seat 27 and the seal 20 to the right of bore 19 defines another chamber 29.
Valve body 10 is mounted on a ba~e 32 having five passageways 33, 34, 35, 36, and 37 aligned and communicating with ;
the five ports 15-19, respectively. Passageway 35 is ¢onnected ;
to a source of pressurized fl~id, such as compressed air, and passageways 33 and 37 are connected to a low pres~ure region, such as the atmosphere, where the fluid whose flow is being con-trolled is air, or a re~ervoir, where the fluid is a liquid.
Passageways 34 and 36 are connected to a working device being 1~83462 controlled by the shuttIe valve, such as the opposite sides of apiston within a cylinder (not shown). To insure a fluid tight connection between valve body lO and base 32, a gasket 38 (Figs.
1 and 2) is provided between the body and base. Gasket 38 has five holes through it, aligned with ports 15-19, respectively, and two slots 39 and 40. Slot 39 establishes communication between the hole in gasket 38 aligned with pressure passageway 35 and a hole 41 in valve body 10 which extends through the valve body to chamber 28, Slot 40 establishes communication between the same hole in gasket 38 and a hole 42 in body 10 which extends through the valve body to chamber 29. Thus, slot 39 and hole 41 define a bleed passageway for continuously supplying high pressure fluid to chamber 28, and slot 40 and hole 42 define a bleed passageway for continuously supplying high pressure fluid to chamber 29.
A shuttle valve member 45 is slidably supported within seals 20 for axial movement within bore 11. Valve member 45 is, in this example, in the form of a generally cylindrical spool having two reduced diameter regions 46. ~lthough valve member 45 is slidable, its engagement with each of seals 20 is fluid tight in~ ature, At each of it~ ends, valve member 45 carries a disk 47 of a material capable of forming a good seal when pressed against one of the valve seats 26 and 27. Valve member 45 has two stable positions shown respec*ively in Figs. 1 and 3. In the position shown in Fig. 1, valve member 45 engages valve seat 27 and is spaced from valve seat 26. In this position, pressure passageway 35 communicates with working device passageway 34 through port 17, bore 10, and port 16. At the same time, exhaust passageway 37 communicates with working device passageway 36 through port 19, bore 10, and port 18. When valve member 45 moves to the position shown in Fig. 3, valve member 45 engages valve seat 26 and is spaced from valve seat 27, In this position, -5~
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pressure passageway 35 communicates with working device passage-way 36 through port 17, bore 10, and port 18. At the same time, exhaust passageway 33 communicates with working device passageway 34 through port 15, bore 10, and port 16.
Movement of shuttle valve member 45 may be controlled by a three-way solenoid operated valve 14 of the type shown in U.S.
Patent ~o. 3,303,854. Body 13 of valve 14 is formed with a bore 49 from which a passageway 50 e~tends to the end of passageway 24 and from which orifice 25 extends. Also extending from bore 49 is a vent port 51 which, in the case o~ air opens to the atmosphere, as shown, but in the case of a liquid would open to a reservoir.
Fixed within bore 49 is a fitting 52 (Figs. 1, 3, and 4) having a T-shaped passageway for establishing communication between passage-way 50 and the region of bore 49 above fitting 52, and another T-shaped passageway for establishing communication between orifice 25 and the region of bore 49 below fitting 52. The vertical stems 53 and 54 of the T-shaped passageways constitute control ports of the valve. Fitting 52 also has a vertical through hole 55 (Fig. ~) through which the regions above and be~ow fitting 52 are in constant communication~ CQnse~uently,~ the region~ of bore 49 above and below fitting 52 are always in communication with vent port 51.
Mounted on body 13 is an electrical solenoid 58 having a depending armature 59 spring biased in a downward direction.
The lower end of armature 59 serves as a valve member for clo~ing and opening the upper end of control port 53. Three vertical pins 60 are slidably arranged in three holes in fitting 52, the pins carrying a valve member 61 at their lower ends. Valve member 61 serves to close and open the lower end of control port 54. The upper ends of pins 60 abut the lower face of solenoid armature 59, and a compression spring 62 constantly urges valve member 61 and hence pins 60 upwardly. However, the spring (not shown) biasing armature 59 downwardly i9 stronger than spring 62. Hence, when . ,. ' . - ' ,, :. :;
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solenoid 58 is deenergized (Fig. 1), armature 59 closes control port 53 and pushes valve member 61 downwardly, via pins 60, to open con-trol port 54. As a result, orifice 25 is exhausted through passage-way 54, bore 49 and port 51, and orifice 23 is blocked, since it communicates with closed control port 53 through passageways 24 and 50. In this condition, high pressure fluid bleeding into chamber 28 from passageway 35 builds up pressure in that chamber and holds shuttle valve member 45 against valve seat 27.. The high pressure which was also bleeding into chamber 29 was just as quickly exhausted through orifice 25 until the end of valve member 45 engaged valve seat 27. With equal pressures in chambers 28 and 29, thereis a net force toward the right on valve member 45, because the entire left end face of the valve member is exposed ~o the pressure while only the annular area of the right end face of the valve member radially outwardly of valve seat 27 is -exposed to the pressure.
When solenoid 58 is energized (Fig. 3), armature 59 is pulled upwardly opening control port 53 and permitting spring 62 to cause valve member 61 to close control port 54. As a result, control port 54 and hence orifice 25 are blocked. On the other hand, orifice 23 is opened to exhaust through passageways 24 and 50, con-trol port 53, bore 49, hole 55, and vent port 51. The pressure in chamber 28 diminishes because control port 53 and all the passage-ways with which it is connected are larger than bleed passageway 39, 41. High pressure remains, howeve~ in chamber 29. When the pressure in chamber 28 decreases to the point where there is a net leftward force on valve member 45, the valve member moves away from valve seat 27 and into engagement with valve seat 26. In this condition, although the same high pressure eventually exists in both chambers 28 and 29, there is a net leftward force on valve member 45, for the reasondescribed above. When solenoid 58 is again deenergized, valve member 45 again moves to the right into : ' :
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the position shown in Fig. lo According to the present invention, each valve seat 26, 27 is made considerably larger than its respective control port 53, 54, i,e., the cross~sectional area of the valve seat is at least fifty tLmes larger, and even 100 or more times larger, than,the cross-sectional area of the control port. The valve seats 26, 27 are also relatively large with respect to the cross-sectional dimen-sion of the shuttle valve member 45 as compared to conventional ;~
valves of this type, Thus, according to the present invention the cross-sectional area of the portion of valve member 45 within chamber 28, 29 is no more than four times the cross-sectional area of the valve seat 26, 27, and is no less than twice the area of the~
valve seat. Preferably, the ratio of the cross-sectional area of ;;~
the valve member to the cross-sectional area of the valve seat is three to one.
To understand the advantages of the area relationships described immediately above, consider the situation when the area of the valve seat is very small with respect to the area of the shuttle valve member. In such a case, when one end of the shuttle valve member is seated against a valve seat, almost as much sur-face area at the seated end face of the valve member is exposed to high pressure as at the unseated end face of the valve member. ~~
Hence, when the control valve changes state, the shuttle valve member begins moving almost immediately after the pressure begins to drop in the chamber whose control port had been blocked, but is now open, and movement continues very slowly, as described in the introductory portion above.
In contrast, in a valve according to the present invention, when the valve is in the condition shown in Fig. 1, a much larger surface area at the end of valve member in chamber 2~ is exposed to high pressure than at the end of the valve member in chamber 29. The reason is that the relatively large area valve seat 27 ,,; ::' ' .
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,, . . :. , .,~, ,. : ,, ", ~08~9L6;2 keeps high pressure fluid in chamber 29 from contacting 25% to 50%of the surface area of the end face of valve member 45 in chamber 29. Thus, when control valve 14 shifts from its condition shown in Fig. 1 to its Fig. 3 condition, valve member 45 will not move right after pressure in chamber 28 begins to drop. Instead, the pressure in chamber 28 will have to drop considerably before a net leftward force develops on valve member 45. Once valve member 45 begins to move, its movement is very rapid for two reasons. First, there is already low pressure in chamber 28, so little or no dashpot effect occurs in that chamber. Secondly, as soon as valve member 45 moves the slightest distance away from valve seat 27, the entire right end face of valve member 45 is exposed to high ;
pressure fluid, and hence a large net leftward force is suddenly applied to the shuttle valve member. This sudden rapid movement of shuttle valve member 45 eliminates, or at least greatly mini-mizes, the chance that the valve member will get stuck bet~een its two stable positions. The description given immediately above obviously applies as well when valve member 45 is moving from its ;;
Fig. 3 position to its Fig. 1 position.
The invention has been described in connection with a ~;
spool-type shuttle valve member. It is equally applicable to a piston-type shuttle valve member as shown in Fig. 5. In Fig. 5, parts corresponding to those shown in Figs. 1-4 bear the same reference numerals followed by a prime. Shuttle valve member 45' comprises two spaced-apart pistons 65, snugly but slidably arranged in bore 11', joined together by a central rod 66 of smaller diameter. The space between pistons 65 is filled with high pressure fluid through port 35'. In this example, high pressure fluid bleed into chambers 28' and 29' through bleed passages 67 extending through the pistons, Rod 45' carries a ;~-cup-like element 68 which causes either working device port 37' ~
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to communicate with exhaust port 34', as shown in ~'ig 5, or work-ing device port 33' to communicate with exhaust port 34'. The working device port not communicating with exhaust port 34' communicates with pressure port 35'. In all other respects, the shuttle valve of Fig. 5 functions in the same manner as the valve of Figs. 1-4. ;~
Ports 53 and 54 have been referred to as the "control ports" of the valve, since in a commercial valve these would ordinarily be the passageways ofrsmallest cross-sectional area between each of chambers 28 and 29 and vent port 51. ~owever, if for some reaso~ some other portion of the communication passageway between either chamber and the vent port were the portion of smallest cross-sectional area, that smallest portion would be con-sidered the control port. For example, if orifices 23 and 25 were ~-: . .
smaller than ports 53 and 54, respectively, orifices 23 and 25 would be considered the control ports.
The invention has been shown and described in preferred form only, and by way of example, and many variations may be made -~
in the invention which will still be comprised within its spirit.
It is understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are included in the appended claims.
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of its respective control port, and such that there is a relatively small ratio between the cross-sectional sizes of the valve member and each valve seat, As a result of employing large valve seats, .:. .
one of which is engaged by an end of the shuttle valve member in each stable position of the valve member, upon a change of state of the control valve, the shuttle valve member does not begin to move until a significant proportion of the pressure in the chamber toward which the valve member will move is exhausted. The reason is that only a relatively small annular area at the end of the shuttle valve member outside the valve seat with which that end is in contact is exposed to the pressure in the chamber away from which the valve member will move. When the shuttle valve member does begin to move, the pressure in the chamber away from whi-ch it i~ moving is high and the pressure in the chamber being exhausted is re~atively low, so that the shuttle valve member is moved very rapidly by the relatively large pressure differential between the two chambers.
Additional objects, features, and explanation of the invention will be apparent from the following description in which reference is made to the accompanying drawings.
In the drawings:
Fig. 1 is a schematic longitudinal cross-sectional view of a spool-type shuttle valve according to the present invention;
Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. l;
Fig. 3 is a view similar to Fig. 1 showing the control valve and the shuttle valve member in an alternative position to that shown in Fig. l;
Fig. 4 is a cross-sectional view taken on line 4-4 of ;
Fig. 3; and Fig. 5 is a schematic longitudinal cross-sectional view of a piston-type shuttle valve according to the present invention.
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The shuttle valve chosen to illustrate the present invention, and shown in Figs. 1-4, includes a valve body 10 having an elongated bore 11. Bore 11 is closed at one end by an end plate 12 and at the other end by the valve body 13 of ~'~control means in the form of a solenoid operated valve 14. End plate 12 and valve body 13 are mounted on valve body 10 in a fluid tight `
manner by suitable fasteners (not shown). Body 10 is formed, in this example, with five ports 15, 16, 17, 18, and 19 in the side wall o~ bore 11. Projecting into bore 11 are six annular seals 20, formed for example of rubber or plastic, one seal being located between each two successive bores, and two seals being arranged beyond the extreme bores 15 and 19, respectively.
At each end, bore 11 is provided with an orifice. One of the orifices 23 is formed in end plate 12 and communicates with a passageway 24 formed in end plate 12 and body 10. The other end of passageway 24 terminates at the face of valve body D0 on which control valve body 13 is mounted~ The second orifice -25 is formed in control valve body 13. Orifice 23 is surrounded by an annular valve seat 26, and orifice 25 is surrounded by an annular valve seat 27, both valve seats~projecting into bore 11.
The end portion of bore 11 between valve seat 26 and the seal 20 to the left of port 15 defines a chamber 28, and the other end portion of bore 11 between valve seat 27 and the seal 20 to the right of bore 19 defines another chamber 29.
Valve body 10 is mounted on a ba~e 32 having five passageways 33, 34, 35, 36, and 37 aligned and communicating with ;
the five ports 15-19, respectively. Passageway 35 is ¢onnected ;
to a source of pressurized fl~id, such as compressed air, and passageways 33 and 37 are connected to a low pres~ure region, such as the atmosphere, where the fluid whose flow is being con-trolled is air, or a re~ervoir, where the fluid is a liquid.
Passageways 34 and 36 are connected to a working device being 1~83462 controlled by the shuttIe valve, such as the opposite sides of apiston within a cylinder (not shown). To insure a fluid tight connection between valve body lO and base 32, a gasket 38 (Figs.
1 and 2) is provided between the body and base. Gasket 38 has five holes through it, aligned with ports 15-19, respectively, and two slots 39 and 40. Slot 39 establishes communication between the hole in gasket 38 aligned with pressure passageway 35 and a hole 41 in valve body 10 which extends through the valve body to chamber 28, Slot 40 establishes communication between the same hole in gasket 38 and a hole 42 in body 10 which extends through the valve body to chamber 29. Thus, slot 39 and hole 41 define a bleed passageway for continuously supplying high pressure fluid to chamber 28, and slot 40 and hole 42 define a bleed passageway for continuously supplying high pressure fluid to chamber 29.
A shuttle valve member 45 is slidably supported within seals 20 for axial movement within bore 11. Valve member 45 is, in this example, in the form of a generally cylindrical spool having two reduced diameter regions 46. ~lthough valve member 45 is slidable, its engagement with each of seals 20 is fluid tight in~ ature, At each of it~ ends, valve member 45 carries a disk 47 of a material capable of forming a good seal when pressed against one of the valve seats 26 and 27. Valve member 45 has two stable positions shown respec*ively in Figs. 1 and 3. In the position shown in Fig. 1, valve member 45 engages valve seat 27 and is spaced from valve seat 26. In this position, pressure passageway 35 communicates with working device passageway 34 through port 17, bore 10, and port 16. At the same time, exhaust passageway 37 communicates with working device passageway 36 through port 19, bore 10, and port 18. When valve member 45 moves to the position shown in Fig. 3, valve member 45 engages valve seat 26 and is spaced from valve seat 27, In this position, -5~
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pressure passageway 35 communicates with working device passage-way 36 through port 17, bore 10, and port 18. At the same time, exhaust passageway 33 communicates with working device passageway 34 through port 15, bore 10, and port 16.
Movement of shuttle valve member 45 may be controlled by a three-way solenoid operated valve 14 of the type shown in U.S.
Patent ~o. 3,303,854. Body 13 of valve 14 is formed with a bore 49 from which a passageway 50 e~tends to the end of passageway 24 and from which orifice 25 extends. Also extending from bore 49 is a vent port 51 which, in the case o~ air opens to the atmosphere, as shown, but in the case of a liquid would open to a reservoir.
Fixed within bore 49 is a fitting 52 (Figs. 1, 3, and 4) having a T-shaped passageway for establishing communication between passage-way 50 and the region of bore 49 above fitting 52, and another T-shaped passageway for establishing communication between orifice 25 and the region of bore 49 below fitting 52. The vertical stems 53 and 54 of the T-shaped passageways constitute control ports of the valve. Fitting 52 also has a vertical through hole 55 (Fig. ~) through which the regions above and be~ow fitting 52 are in constant communication~ CQnse~uently,~ the region~ of bore 49 above and below fitting 52 are always in communication with vent port 51.
Mounted on body 13 is an electrical solenoid 58 having a depending armature 59 spring biased in a downward direction.
The lower end of armature 59 serves as a valve member for clo~ing and opening the upper end of control port 53. Three vertical pins 60 are slidably arranged in three holes in fitting 52, the pins carrying a valve member 61 at their lower ends. Valve member 61 serves to close and open the lower end of control port 54. The upper ends of pins 60 abut the lower face of solenoid armature 59, and a compression spring 62 constantly urges valve member 61 and hence pins 60 upwardly. However, the spring (not shown) biasing armature 59 downwardly i9 stronger than spring 62. Hence, when . ,. ' . - ' ,, :. :;
9 ~33~6Z
solenoid 58 is deenergized (Fig. 1), armature 59 closes control port 53 and pushes valve member 61 downwardly, via pins 60, to open con-trol port 54. As a result, orifice 25 is exhausted through passage-way 54, bore 49 and port 51, and orifice 23 is blocked, since it communicates with closed control port 53 through passageways 24 and 50. In this condition, high pressure fluid bleeding into chamber 28 from passageway 35 builds up pressure in that chamber and holds shuttle valve member 45 against valve seat 27.. The high pressure which was also bleeding into chamber 29 was just as quickly exhausted through orifice 25 until the end of valve member 45 engaged valve seat 27. With equal pressures in chambers 28 and 29, thereis a net force toward the right on valve member 45, because the entire left end face of the valve member is exposed ~o the pressure while only the annular area of the right end face of the valve member radially outwardly of valve seat 27 is -exposed to the pressure.
When solenoid 58 is energized (Fig. 3), armature 59 is pulled upwardly opening control port 53 and permitting spring 62 to cause valve member 61 to close control port 54. As a result, control port 54 and hence orifice 25 are blocked. On the other hand, orifice 23 is opened to exhaust through passageways 24 and 50, con-trol port 53, bore 49, hole 55, and vent port 51. The pressure in chamber 28 diminishes because control port 53 and all the passage-ways with which it is connected are larger than bleed passageway 39, 41. High pressure remains, howeve~ in chamber 29. When the pressure in chamber 28 decreases to the point where there is a net leftward force on valve member 45, the valve member moves away from valve seat 27 and into engagement with valve seat 26. In this condition, although the same high pressure eventually exists in both chambers 28 and 29, there is a net leftward force on valve member 45, for the reasondescribed above. When solenoid 58 is again deenergized, valve member 45 again moves to the right into : ' :
, ~08~
the position shown in Fig. lo According to the present invention, each valve seat 26, 27 is made considerably larger than its respective control port 53, 54, i,e., the cross~sectional area of the valve seat is at least fifty tLmes larger, and even 100 or more times larger, than,the cross-sectional area of the control port. The valve seats 26, 27 are also relatively large with respect to the cross-sectional dimen-sion of the shuttle valve member 45 as compared to conventional ;~
valves of this type, Thus, according to the present invention the cross-sectional area of the portion of valve member 45 within chamber 28, 29 is no more than four times the cross-sectional area of the valve seat 26, 27, and is no less than twice the area of the~
valve seat. Preferably, the ratio of the cross-sectional area of ;;~
the valve member to the cross-sectional area of the valve seat is three to one.
To understand the advantages of the area relationships described immediately above, consider the situation when the area of the valve seat is very small with respect to the area of the shuttle valve member. In such a case, when one end of the shuttle valve member is seated against a valve seat, almost as much sur-face area at the seated end face of the valve member is exposed to high pressure as at the unseated end face of the valve member. ~~
Hence, when the control valve changes state, the shuttle valve member begins moving almost immediately after the pressure begins to drop in the chamber whose control port had been blocked, but is now open, and movement continues very slowly, as described in the introductory portion above.
In contrast, in a valve according to the present invention, when the valve is in the condition shown in Fig. 1, a much larger surface area at the end of valve member in chamber 2~ is exposed to high pressure than at the end of the valve member in chamber 29. The reason is that the relatively large area valve seat 27 ,,; ::' ' .
, . : ~ . ~ , , : :
,, . . :. , .,~, ,. : ,, ", ~08~9L6;2 keeps high pressure fluid in chamber 29 from contacting 25% to 50%of the surface area of the end face of valve member 45 in chamber 29. Thus, when control valve 14 shifts from its condition shown in Fig. 1 to its Fig. 3 condition, valve member 45 will not move right after pressure in chamber 28 begins to drop. Instead, the pressure in chamber 28 will have to drop considerably before a net leftward force develops on valve member 45. Once valve member 45 begins to move, its movement is very rapid for two reasons. First, there is already low pressure in chamber 28, so little or no dashpot effect occurs in that chamber. Secondly, as soon as valve member 45 moves the slightest distance away from valve seat 27, the entire right end face of valve member 45 is exposed to high ;
pressure fluid, and hence a large net leftward force is suddenly applied to the shuttle valve member. This sudden rapid movement of shuttle valve member 45 eliminates, or at least greatly mini-mizes, the chance that the valve member will get stuck bet~een its two stable positions. The description given immediately above obviously applies as well when valve member 45 is moving from its ;;
Fig. 3 position to its Fig. 1 position.
The invention has been described in connection with a ~;
spool-type shuttle valve member. It is equally applicable to a piston-type shuttle valve member as shown in Fig. 5. In Fig. 5, parts corresponding to those shown in Figs. 1-4 bear the same reference numerals followed by a prime. Shuttle valve member 45' comprises two spaced-apart pistons 65, snugly but slidably arranged in bore 11', joined together by a central rod 66 of smaller diameter. The space between pistons 65 is filled with high pressure fluid through port 35'. In this example, high pressure fluid bleed into chambers 28' and 29' through bleed passages 67 extending through the pistons, Rod 45' carries a ;~-cup-like element 68 which causes either working device port 37' ~
_g_ ,~ ` ' ' .
to communicate with exhaust port 34', as shown in ~'ig 5, or work-ing device port 33' to communicate with exhaust port 34'. The working device port not communicating with exhaust port 34' communicates with pressure port 35'. In all other respects, the shuttle valve of Fig. 5 functions in the same manner as the valve of Figs. 1-4. ;~
Ports 53 and 54 have been referred to as the "control ports" of the valve, since in a commercial valve these would ordinarily be the passageways ofrsmallest cross-sectional area between each of chambers 28 and 29 and vent port 51. ~owever, if for some reaso~ some other portion of the communication passageway between either chamber and the vent port were the portion of smallest cross-sectional area, that smallest portion would be con-sidered the control port. For example, if orifices 23 and 25 were ~-: . .
smaller than ports 53 and 54, respectively, orifices 23 and 25 would be considered the control ports.
The invention has been shown and described in preferred form only, and by way of example, and many variations may be made -~
in the invention which will still be comprised within its spirit.
It is understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are included in the appended claims.
'',' . .
., .
. ,. :, . .
: ~
Claims (7)
1. A shuttle valve comprising:
(a) a valve body having an elongated bore and a plural-ity of ports communicating with the bore through the side wall of the bore, one of said ports being connectable to a source of pressurized fluid, (b) a first orifice in said valve body at one end of the bore and a second orifice in said valve body at the other end of the bore, (c) first and second valve seats surrounding said first and second orifices, respectively, said valve seats pro-jecting into the bore, (d) a shuttle valve member slidable axially within the bore to control the flow of fluid between said side wall ports, said shuttle valve member being slidable between two stable posi-tions in which (I) one end face of said valve member engages said first valve seat and the other end face of said valve member is spaced from said second valve seat, or (II) said other end face of said valve member engages said second valve seat and said one end face of said valve member is spaced from said first valve seat, (e) the ratio of the cross-sectional area of said valve member to the cross-sectional area of each of said valve seats being in the range between 2 to 1 and 4 to 1, (f) each end portion of said bore defining a chamber adjacent to the orifice and valve seat at that end, (g) bleed passageways for supplying pressurized fluid to both of said chambers, and (h) control means for alternatively (I) connecting said first orifice to a low pressure region and blocking said second orifice, to move said valve member against said first valve seat, and (II) connecting said second orifice to a low pressure region and blocking said first orifice, to move said valve member against said second valve seat.
(a) a valve body having an elongated bore and a plural-ity of ports communicating with the bore through the side wall of the bore, one of said ports being connectable to a source of pressurized fluid, (b) a first orifice in said valve body at one end of the bore and a second orifice in said valve body at the other end of the bore, (c) first and second valve seats surrounding said first and second orifices, respectively, said valve seats pro-jecting into the bore, (d) a shuttle valve member slidable axially within the bore to control the flow of fluid between said side wall ports, said shuttle valve member being slidable between two stable posi-tions in which (I) one end face of said valve member engages said first valve seat and the other end face of said valve member is spaced from said second valve seat, or (II) said other end face of said valve member engages said second valve seat and said one end face of said valve member is spaced from said first valve seat, (e) the ratio of the cross-sectional area of said valve member to the cross-sectional area of each of said valve seats being in the range between 2 to 1 and 4 to 1, (f) each end portion of said bore defining a chamber adjacent to the orifice and valve seat at that end, (g) bleed passageways for supplying pressurized fluid to both of said chambers, and (h) control means for alternatively (I) connecting said first orifice to a low pressure region and blocking said second orifice, to move said valve member against said first valve seat, and (II) connecting said second orifice to a low pressure region and blocking said first orifice, to move said valve member against said second valve seat.
2. A shuttle valve as defined in Claim 1 wherein the ratio of the cross-sectional area of said valve member to the cross-sectional area of each of said valve seats is no more than 3 to 1.
3. A shuttle valve as defined in Claim 1 wherein said bleed passageways establish continuous communication between said side wall port connectable to a source of pressurized fluid and each of said chambers.
4. A shuttle valve as defined in Claim 3 including a base connected to said valve body, said base having ports communi-cating with said side wall ports in said body, and a gasket between said valve body and said base, said bleed passageways being formed in said gasket.
5. A shuttle valve as defined in Claim 3 wherein said bleed passageways are located within said valve member.
6, A shuttle valve as defined in Claim 1 wherein the cross-sectional area of each control port is a fraction of the cross-sectional area of its respective valve seat.
7. A shuttle valve as defined in Claim 6 wherein the ratio of the cross-sectional area of each control port to the cross-sectional area of its respective valve seat is no greater than 1 to 50.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US85457877A | 1977-11-25 | 1977-11-25 | |
| US854,578 | 1977-11-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083462A true CA1083462A (en) | 1980-08-12 |
Family
ID=25319078
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA312,120A Expired CA1083462A (en) | 1977-11-25 | 1978-09-26 | Shuttle valve |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS54116737A (en) |
| AU (1) | AU529028B2 (en) |
| CA (1) | CA1083462A (en) |
| DE (1) | DE2850796A1 (en) |
| FR (1) | FR2410197A1 (en) |
| GB (1) | GB2008721B (en) |
| NL (1) | NL7811578A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19733660A1 (en) † | 1997-08-04 | 1999-02-25 | Bosch Gmbh Robert | Electromagnetic pressure control valve |
| DK2894353T3 (en) | 2014-01-13 | 2017-07-10 | Danfoss Power Solutions Aps | ELECTRO-HYDRAULIC CONTROL VALVE |
-
1978
- 1978-09-26 CA CA312,120A patent/CA1083462A/en not_active Expired
- 1978-10-06 AU AU40484/78A patent/AU529028B2/en not_active Expired
- 1978-11-23 GB GB7845807A patent/GB2008721B/en not_active Expired
- 1978-11-23 DE DE19782850796 patent/DE2850796A1/en not_active Withdrawn
- 1978-11-23 FR FR7833063A patent/FR2410197A1/en active Granted
- 1978-11-24 NL NL7811578A patent/NL7811578A/en not_active Application Discontinuation
- 1978-11-25 JP JP14523278A patent/JPS54116737A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2008721A (en) | 1979-06-06 |
| FR2410197B3 (en) | 1981-03-06 |
| FR2410197A1 (en) | 1979-06-22 |
| JPS54116737A (en) | 1979-09-11 |
| AU529028B2 (en) | 1983-05-26 |
| DE2850796A1 (en) | 1979-05-31 |
| NL7811578A (en) | 1979-05-29 |
| GB2008721B (en) | 1982-02-24 |
| AU4048478A (en) | 1980-07-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |