| United States Patent | 3,581,756 |
| Pettis, Jr. | June 1, 1971 |
FLUIDIC INTERFACE
Abstract
The fluidic interface includes a spring-loaded, double-headed piston adapted to alternatively open and close at least one back pressure fluidic output in response to the presence of high-pressure power fluid applied at the input of the interface. The interface serves to prevent cross contamination between the power fluid source and the fluidic input.
| Inventors: | Pettis, Jr.; Charles R. (Ithaca, NY) |
| Assignee: |
Hi-Speed Checkweigher Co., Inc.
(Ithaca,
NY)
|
| Appl. No.: | 04/777,622 |
| Filed: | November 21, 1968 |
| Current U.S. Class: | 251/62 ; 235/201ME |
| Current International Class: | F15B 21/00 (20060101); F15C 1/00 (20060101); F15c 003/02 () |
| Field of Search: | 235/201,200 137/81.5 91/3 |
| 3081942 | March 1963 | Maclay |
| 3090552 | May 1963 | Raider |
| 3124999 | March 1964 | Woodward |
| 3407828 | October 1968 | Jones |
| 3461777 | August 1969 | Spencer |
| 442,031 | Jan., 1968 | CH | |||
I claim:
1. A fluidic interface having utility in the control of a fluidic air circuit in accordance with pressure and no-pressure fluid conditions occurring in a power fluid circuit, said fluidic circuit including at least one fluidic air back pressure switch, said switch being connectable to a back pressure line and being constructed such that the output of said switch is determined by the blocking or venting of said back pressure line to atmosphere, said interface comprising:
a housing having a stepped, through bore opening, said housing opening having axially aligned input and output opening portions, said input opening portion is of a diameter greater than said output opening portion, said input opening portion being axially closed by an end plate fixed to said housing, said end plate being apertured to connect said input opening portion to said power fluid circuit;
a piston received for reciprocation axially within said housing opening, said piston having input and output head portions slidably supported within said input and output opening portions, respectively, said input head portion being exposed to said pressure and no-pressure conditions of said power fluid; and
resilient means, said resilient means being disposed in engagement with said input head portion of said piston and normally serving to bias same towards said end plate, whereby during a pressure condition said power fluid engaging said input head portion forces said piston to reciprocate axially of said housing opening away from said end plate against the return bias of said resilient means, said output opening portion being in flow communication with the atmosphere, and said housing having a passageway opening into said output opening portion and being connectable to said back pressure line, said output head portion when said piston is reciprocated from and towards said end plate being adapted to alternately block and unblock said housing passageway so as to alternately block and vent said back pressure line to atmosphere.
2. A fluidic interface having utility in the control of a fluidic air circuit in accordance with pressure and no-pressure fluid conditions occurring in a power fluid circuit, said fluidic circuit including at least one fluidic air back pressure switch, said switch being connectable to a back pressure line and being constructed such that the output of said switch is determined by the blocking or venting of said back pressure line to atmosphere, said interface comprising:
a housing having an opening, said housing opening having axially aligned input, intermediate and output opening portions, said housing having a bleed passageway placing said intermediate opening portion in communication with the atmosphere, and said housing having a passageway opening into said output opening portion and being connectable to said back pressure line;
a piston received for reciprocation axially within said housing opening, said piston having input and output head portions slidably supported within said input and output opening portions, respectively; and
resilient means tending to normally maintain said piston in a first position axially of said housing opening, said input opening portion being connectable to said power fluid circuit such that said input head portion is exposed to said pressure and no-pressure conditions existing therein, whereby during a pressure condition said power fluid engaging said input head portion forces said piston to reciprocate axially of said housing opening away from said first position against the return bias of said resilient means, said output opening portion passageway being normally blocked by said output head portion when said input head portion is exposed to a no-pressure condition and unblocked when said input head portion is exposed to a pressure condition, and said output opening portion passageway when unblocked venting said back pressure line to the atmosphere serially through said output opening portion, said intermediate opening portion and said bleed passageway.
3. A fluidic interface having utility in the control of a fluidic air circuit in accordance with pressure and no-pressure fluid conditions occurring in a power fluid circuit, said fluidic circuit including at least a pair of fluidic air back pressure switch, said switches being connectable to a pair of back pressure lines and being constructed such that the outputs of said switches are determined by the blocking or venting of said back pressure lines to atmosphere, said interface comprising;
a housing having a stepped, through bore opening, said housing opening having axially aligned input, intermediate and output opening portions, said intermediate opening portion being normally in flow communication with the atmosphere through a bleed passageway, said housing having a pair of housing passageways spaced apart axially of said output opening portion, and said switches being connected one to each of said housing passageways by said back pressure lines;
a piston received for reciprocation axially within said housing opening, said piston having input and output head portions slidably supported within said input and output opening portions, respectively; and
resilient means tending to normally maintain said piston in a first position axially of said housing opening, said input opening portion being connectable to said power fluid circuit such that said input head portion is exposed to said pressure and no-pressure conditions existing therein, whereby during a pressure condition said power fluid engaging said input head portion forces said piston to reciprocate axially of said housing opening away from said first position against the return bias of said resilient means, said output opening portion being in flow communication with the atmosphere, said housing passageways being alternately blocked and unblocked by said output head portion when said piston is reciprocated within said opening, one of said housing passageways being directly vented to atmosphere through said output opening portion when said input head portion is exposed to a no-pressure condition and the other of said housing passageways being vented to atmosphere serially through said output opening portion, said intermediate opening portion and said bleed passageway when said input head portion is exposed to a pressure condition.
4. A fluidic interface according to claim 3, wherein said input opening portion is axially closed by an end plate mounted on said housing, said end plate being apertured to place said input opening portion in flow communication with said power fluid circuit, and said resilient means includes a compression spring retained within said intermediate opening portion, said spring normally tending to bias said input head portion into engagement with said end plate.
BACKGROUND OF THE INVENTION
Heretofore, when desiring to control operation of a fluidic circuit by an available source of power fluid, such as air, having alternating pressure and no-pressure conditions, it has been common practice to pass power air directly to a gate of the fluidic circuit through a choke, which serves to reduce the power air source line pressure to a sufficiently low level for use in the fluidic circuit. This arrangement has the disadvantage that any lubricant or other foreign matter entrained within the power air is admitted into the fluidic circuit, where its presence may adversely effect circuit performance.
SUMMARY OF THE INVENTION
The present invention is directed to a fluidic interface adapted to prevent the possibility of cross contamination between an available source of power fluid, such as air, and a fluidic input.
The present interface includes a housing bored to receive a spring-biased double-headed reciprocating piston and includes one or more back pressure fluidic outputs. When power fluid is piped through the input of the interface, it serves to move the piston against the bias of the spring so as to selectively block or vent the back pressure fluidic outputs for the purpose of controlling operation of back pressure switches provided in the fluidic circuit. The position of the piston may be observed through a vent opening in the housing so as to permit the condition of the interface to be visually ascertained at all times.
THE DRAWINGS
The nature and mode of operation of the interface of the present invention will now be described with reference to the accompanying drawing wherein:
FIG. 1 is a diagrammatic view illustrating how the interface of the present invention may be employed to connect an available power fluid circuit to a fluidic circuit, and
FIG. 2 is a sectional view of the interface of the present invention.
DETAILED DESCRIPTION
By now referring to FIG. 1, it will be understood that the interface of the present invention, which is generally designated as 1, is employed to connect an available power fluid circuit, generally indicated at 2, and a fluidic circuit, generally indicated at 3.
The interface of the present invention is not limited to use with any specific type of power fluid or fluidic circuit. Rather, it has utility whenever it is desired to control operation of the fluidic circuit by control signals in the form of alternating pressure or no-pressure conditions occurring within the power fluid circuit normally employed to effect operation of diverse art devices.
For purposes of illustration, however, the fluidic circuit is shown as including a pair of back pressure switches 4 and 5, which are connected to interface 1 by back pressure lines 6 and 7, respectively. It will be understood that switches 4 and 5 are of conventional construction, such that when lines 6 and 7 are vented to atmosphere, clean, dry fluidic circuit air admitted at switch inlet ports 4 a, 5 a passes as output signals through ports 4 b, 5 b, respectively. However, when lines 6 and 7 are blocked the outputs will switch to ports 4 c and 5 c, respectively.
Further, for purposes of illustration, the power fluid circuit is shown as including a suitably operated two-position, four-way valve 8, which serves to alternately connect opposite ends of a double-acting cylinder 9 to source pressure and vent lines 10 and 11, respectively, via connection lines 12 and 13. Cylinder 9 may be employed to operate a part of an art device, not shown, with which the power fluid circuit is associated. In the position of valve 8 illustrated in FIG. l, line 13 is vented or in its no-pressure condition, whereas power fluid is admitted to cylinder 9 through line 12, so as to effect reciprocation of cylinder piston 15 in the direction indicated by arrow 16. In the arrangement illustrated, an interface control line 18 is connected into line 13 for the purpose of exposing the input of interface 1 to alternating pressure and no-pressure conditions existing within line 12, which are occasioned by the operation of valve 8. It will be understood that the power fluid employed may be either a liquid or a gas, such as air.
Interface 1 is best shown in FIG. 2 as including a housing 20, which is provided with a stepped through bore opening 21 having axially aligned input, intermediate and output bore portions 21 a, 21 b and 21 c, respectively, and an input bore opening closure plate 22, which is suitable secured to housing 20 as by means of a plurality of through bolts 23. Housing 20 is further provided with a fluidic air bleed passageway 25, which serves to place intermediate bore portion 21b in flow communication with the atmosphere, and a pair of fluidic back pressure passageways 26, 27, which extend radially from output bore portion 21 c. Back pressure lines 6 and 7 may be suitably connected into the outer ends of passageways 26 and 27, respectively, by any suitable couplings, not shown. End plate 22 is formed with a centrally disposed aperture 28 into which line 18 is fitted in order to place input bore portion 21 a in flow communication with the power fluid.
Interface 1 additionally includes a double-headed piston 30 having an input or enlarged diameter piston head portion 30 a, which is slidably supported for reciprocation within output bore portion 21 c. Piston head portions 30 a, 30 c may be integrally formed or suitably connected for simultaneous movement by means of rod 30 b.
A suitable compression spring 32, which is suitably retained within intermediate bore portion 21 b, is adapted to engage input piston head portion 30 a and normally bias same to the left, as viewed in FIG. 2 into engagement with end plate 22, whereby serving to maintain piston 30 in a first or normal rest position.
Operation of the interface of the present invention will now be described with reference to the drawings, wherein valve 8 is shown as being positioned so as to vent lines 13, 18 and thereby create a no-pressure condition at the input of the interface. When a no-pressure condition exists, spring 32 operates to bias piston head 30 to the left, as viewed in FIG. 2, so as to place piston head 30 c in the position illustrated, wherein it serves to block passageway 27 and unblock passageway 26. When passageway 26 is unblocked, back pressure line 6 is vented or placed in flow communication with the atmosphere through bore portion 21 c, thereby permitting switch 4 to produce an output signal at port 4 b. When passage 27 is blocked, the operation of switch 5 is such that pressure buildup is experienced within line 7, which in turn forces switch 5 to produce an output at port 5c.
When valve 8 is operated to place line 13 in flow communication with source pressure line 10 in order to retract piston rod 15, piston head 30 is simultaneously forced to move to the right, as viewed in FIG. 2 by power fluid acting on head portion 30 a, against the return bias of spring 32 so as to block passageway 26 and unblock passageway 27. When passageway 27 is unblocked, line 7 is vented or placed in flow communication with the atmosphere via bore portions 21 c, 21 b and air bleed opening 25. Upon the blocking and unblocking of passageways 26 and 27, respectively, switches 4 and 5 will be operated to provide output signals at ports 4 c and 5 b, respectively. Any power fluid leaking past piston head 30 a will be immediately vented to atmosphere via bore portion 11 b and bleed opening 25 in order to completely remove the possibility of any cross contamination between the power fluid and the fluidic air.
In the embodiment illustrated, the axial dimension and distance through which piston head 30 c is reciprocated is such as to block and unblock passageways 26, 27 in an alternating fashion. It will be apparent, however, that passageways 26 and 27 may be arranged, so as to permit them to be simultaneously blocked or unblocked.
In addition to permitting the venting to atmosphere of back pressure passageway 26, bore portion 21c permits the position of piston head 30c to be observed, in order to readily indicate the condition of interface 1 and thus the condition of back pressure switches 4 and 5.
Interface housing 20 may be of any desired cross-sectional configuration and formed of any suitable material, such as anodized aluminum. In a like fashion, the construction and material from which piston 30 is formed may vary depending upon the temperature, pressure and degree of corrosiveness of the power fluid to which the interface is exposed. Preferably, however, piston 30 is formed of a plastic material, such as "Delrin" which is an acetal resin well known as an abrasive-resistant, self-lubricating bearing material. By thus forming the piston and/or by providing a suitable friction-reducing liner in the housing bore opening, a good fluid seal may be maintained between the piston and the housing without need for employing lubricants, which might lead to contamination of the fluidic circuit.
While the fluidic interface of the present invention has been described as having a pair of back pressure passageways, it will be understood that any desired number may be employed. Thus, it is to be understood that all matters herein set forth or shown in the accompanying drawing are to be interpreted as illustrative only and not in a limiting sense.
Copyright 2008−2012 Patents.com
