Abstract:
Automatic device for economizing compressed air comprises a means for ensuring the passage of driving fluid under pressure during most of the stroke of the moving element of a user apparatus. The device consists of a single-unit body having a first circuit connecting a fluid supply pipe to one chamber of the cylinder actuator. The first circuit is controlled by a valve moving with a piston subjected to the action of an elastic means and slidably mounted in the body. The piston is actuated by the presence or absence of a pressure signal, the body having a second circuit by-passing the first circuit and connecting a fluid exhaust pipe to the cylinder chamber.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an automatic device for economizing compressed air. 
     2. Related Art 
     French Pat. No. 82 05 042 and its certificate of addition No. 83 03 513 cover a compressed air economizing device permitting the driving fluid pressure of a user-apparatus such as a cylinder actuator to be adjusted to a pressure lower than the pressure in the distribution network. 
     That device comprises a means of ensuring passage of the fluid under pressure during most of the stroke of the cylinder&#39;s moving element and blocks passage of the pressurized fluid before or at the end of the stroke of said moving element. 
     The certificate of addition, No. 83 03 513, describes such an economizing device constructed in the form of a single-unit fitting readily mountable on a cylinder, a pipe or a directional valve, which can be built very simply and cost-effectively. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The present invention is directed to an improved economizing device of the same type incorporated in a single-unit fitting designed to equip only one chamber of a double-acting cylinder. 
     The invention accordingly provides a device consisting of a fitting having a first circuit connecting a fluid supply pipe to a cylinder chamber. The first circuit is controlled by a valve which moves with a piston slidably driven by an elastic means within the fitting. The piston is actuated by the presence or absence of a pressure signal. The fitting has a second circuit short-circuiting the first circuit and connecting a fluid exhaust pipe to the cylinder chamber. The second circuit is controlled by a check valve and the top of the fitting is provided with a means for adjusting the tension of the elastic means and pursuant, the speed of the cylinder&#39;s moving element. 
     This device permits stopping the supplying of fluid to the cylinder before, or at, the end of the piston stroke and also permits adjusting the speed of the piston to suit the work required. 
     Control of the check valve is obtained either by the drop in pressure of the exhaust fluid or by a pressure signal generated by an end-of-travel detector in the cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will be more readily understood in reading the following description of several embodiments with reference to the appended drawings in which: 
     FIG. 1 is a cutaway view, taken longitudinally, of a single-unit economizing device of the pressure drop type, connected to one end of a cylinder actuator; 
     FIG. 2 is a cutaway view of an economizing device identical to that of FIG. 1 and comprising only one valve operating in both directions; 
     FIG. 3 is a cutaway view of an alternative embodiment of the device in FIG. 1; 
     FIG. 4 is a cutaway view of an economizing device with axially aligned pipes; 
     FIG. 5 is a cutaway view of an alternative embodiment of the device in FIG. 4; 
     FIG. 6 is a cutaway view of an economizing device fitted to an apparatus and specifically to a directional valve; 
     FIG. 7 is a cutaway view of an economizing device sandwiched between two apparatuses; 
     FIG. 8 is a cutaway view of an economizing device wherein the piston contains a passage for the exhaust fluid; 
     FIG. 9 is a cutaway view of an economizing device containing a normally-closed valve actuated by pressure drop; 
     FIG. 10 is a cutaway view of a variant of FIG. 9; 
     FIG. 11 is a cutaway view of an economizing device with a normally-closed valve actuated by a pressure signal; 
     FIG. 12 is a cutaway view of an economizing device with a normally-closed valve actuated by a pressure signal; 
     FIG. 13 is a cutaway view of a variant of the device shown in FIG. 12; 
     FIG. 14 is a cutaway view of an economizing device with a normally-open valve actuated sideways by a pressure signal; 
     FIG. 15 is a cutaway view of a variant of the device shown in FIG. 14, with axially aligned ports; and 
     FIG. 16 is a cutaway view of a variant of the device shown in FIG. 8, actuated by a pressure signal. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a cylinder actuator 1 in which is slidably mounted a piston 2 consisting of a rod 3 driving any suitable unit not shown in the drawing. A compressed air economizing device 4 is fitted between one of the chambers 1a of the cylinder and a directional valve 5 operable to alternatively connect chamber 1a to a compressed air source or to the atmosphere. The other chamber 1b of the cylinder is connected directly via a pipe 6 to the directional valve 5, although it would be possible to also equip the pipe 6 with an economizing device identical to economizing device 4. 
     The economizing device 4 consists of a tubular body 7, having a threaded bottom portion 8 for screwing into the tapped port of a supporting means and a cylindrical portion on which is fitted a collar 9 with a pipe connection 10 for fluid flow to pipe 11 and chamber 1a of the cylinder, said connection 10 extending at a right angle to the axis of body 7. 
     The body 7 of the device incorporates a valve 12 connected to a piston 13 via a stem 14 and operable to close off the passage between duct 15 and the opening of connection 10 when pushed against a valve seat 16 provided in the body 7. A tubular space above seat 16 communicates via openings 17 provided therein with a flow channel 18 in pipe connection 10 leading to pipe 11. 
     Flow channel 18 is provided with slots 19 which are closed off on the outside of said channel by a flexible sleeve 20 which is attached at one end and free to open at the other end to allow fluid to pass from pipes 11 and 18 in the direction of a tubular section 21 issuing into duct 15 to bypass the seat 16 of valve 12. This sleeve 20 forms a check valve enabling the fluid to pass only in the direction from chamber 1a to directional valve 5. 
     The top of body 7 has a threaded section mating with a plug 22, said plug having a center cavity 24 housing a spring 23 which pushes against the larger cross-sectional side of piston 13 such that the compression of spring 23 is adjusted in relation to the piston and the valve 12 to adjust the flow rate of the fluid and the speed of piston 2. Cavity 24 extends toward the top of plug 22 and opens, via openings 25, into a pipe connection 26 being part of a collar 27 fitted externally onto the top part of plug 22 and extending at a right angle to the axis of body 7. 
     Pipe connection 26 connects via pressure tap pipe 28 to the fluid outlet 6 of cylinder 1 chamber 1b. 
     When the cylinder piston 2 moves in the direction of arrow F in FIG. 1, the fluid escaping through pipe 6 transfers its pressure through pipe 28 to chamber 29 located above piston 13 such that the large face 13a of piston 13 is subjected to the combined pressure of the spring 23 and the exhaust fluid from cylinder chamber 1b. The small face 13b of piston 13 is subjected to the pressure action of the intake or driving fluid. Consequently, valve 12 moves to open position, allowing the driving fluid to pass through pipes 18 and 11 and into chamber 1a. 
     However, as soon as piston 2 reaches the end of its stroke, the exhaust fluid pressure disappears and no longer acts on the large face 13a of piston 13. Consequently, valve 12 closes due to the force of the driving fluid on the small face 13b of piston 13, said force being greater than that of the spring 23. 
     Lacking pressure in chamber 17, on the other hand, valve 12 returns to open position, pushed by spring 23. 
     When the cylinder piston 2 travels opposite the direction of arrow F and chamber 1a is in exhaust position, fluid flows out through pipe 11 to pipe 18 and pushes the small face 13b of piston 13 while the large face 13a of the piston is subjected to the action of the driving fluid and the spring which keep the valve 12 open. 
     Moreover, the fluid can escape into the annular space 21 and duct 15 toward the directional valve 5, by passing through the check valve 20, thus boosting the exhaust flow. 
     The speed of piston 2 can be varied by acting upon plug 22, screwing the plug in or out to change the tension on spring 23 and the fluid passage between seat 16 and valve 12. 
     FIG. 2 shows an economizing device identical to that of FIG. 1, except that in this embodiment, a valve is used which by itself ensures passage of the fluid on intake and exhaust. 
     To this end, valve 30 has a stem 31 adapted to slide in a blind hole 32 formed in the bottom of piston 13, said valve 30 being subjected to the action of a spring 33 acting in the direction of closure of valve 30. 
     Pipe connection 10 has only 1 channel 18 and the check valve 20 shown in FIG. 1 has been eliminated. When cylinder chamber 1a is supplied with driving fluid such that the exhaust fluid flows out of cylinder chamber 1b, the piston 13 is held in down by spring 23 in combination with the pressure of the exhaust fluid leaving pipe 28, so that valve 30 stays open and allows passage of the driving fluid into pipe 11. 
     As soon as the exhaust fluid pressure lets off on the large face 13a of piston 13, piston 13 moves up in response to the pressure acting on its small face 13b, thus allowing valve 30 to close against the seat 16 due to the pressure of spring 33. 
     Nevertheless, when the exhaust fluid flows the opposite way, through pipe 11 towards duct 15, valve 30 being independent of piston 13, this results in spring 33 being compressed by the fluid pressure and enabling valve 30 to open and the fluid to escape into duct 15. 
     Adjustment of the speed of piston 2 is done in the same way as above by acting on plug 22 and compressing spring 23 to a greater or lesser extent to allow a larger or smaller passage between the valve 30 and its seat 16. 
     FIG. 3 shows an economizing device analogous to that of FIG. 1, except that the plug 22 is fixed and cannot serve as a means of adjusting the tension of spring 23 as in FIG. 1 to control the fluid flow opening and the travel speed of piston 2 in the cylinder. 
     In the embodiment depicted in FIG. 4, the device comprises a main body 7 having a threaded part 34 at its base engaged into a tapped hole in a secondary body consisting of 2 pipe connections--fluid inlet 35 and outlet 36--which are axially aligned with one another at a right angle to the axis of the main body 7. 
     This provides a direct passage for the fluid due to the fact that the device can be fitted to a line 11, 11a connected on one side to the cylinder and on the other side to the directional valve. 
     The control means for valve 30 is identical to that which was the object of the embodiment of FIG. 2. 
     The economizing device illustrated in FIG. 5 is the same as the one of FIG. 3, except that, like the previous one, it includes a secondary body consisting of two pipe connections 35, 36 axially aligned with one another. The control means for valve 12 and the check valve 20 are the same as those featured in FIG. 3, which lack means for adjusting the tension of spring 23. 
     FIG. 6 shows an economizing device comprising a body 37 with a flat surface 38 through which it is attached to a corresponding surface of an apparatus, in particular a directional valve 30 having ports 40, 40a and 40b aligned with the intake and exhaust ports of the economizing device. 
     Valve 30 is controlled by a piston 13 in the same way as described above for the device in FIG. 2. 
     FIG. 7 shows a device identical to that of FIG. 6, except that it is sandwiched between two apparatuses 41 and 42. To this effect the body 37 of the device is given two flat surfaces 37a, 37b which apply to corresponding surfaces on the two apparatuses. 
     Ports 43a, b and c of the apparatuses are in direct communication with the ports of the economizing device body 37. 
     FIG. 8 shows an economizing device wherein the body 7 contains a piston 44 having a blind hole 32 in which is slidably mounted the stem 31 of valve 30. 
     The top of body 7 is closed off by a plug 45 against which presses one end of a spring 46 whose other end presses against a piston 44. A tapped hole is provided in plug 45 for receiving a screw 47 having an end pin 48 bearing on members 49 attached to piston 44. 
     This feature enables compression adjustment of spring 46 by adjusting the screw 47 and piston 44 in order to adjust the air output and, following, the speed of cylinder piston 2. 
     Above pipe connection 10, body 7 is fitted with a collar 27 and pipe connection 26 connected via pipe 28 to the exhaust of cylinder chamber 1b. Pipe connection 26 has a slanted duct 50 issuing into an annular space 51 communicating via an aperture 52 in body 7 and a center bore 53 in piston 44 with an chamber 54 located above piston 44. 
     The part of chamber 54 which is located under the piston is vented to the atmosphere via a duct 55 in body 7, an annular space 56 separated from annular space 51 by an O-ring 57, an an aperture 58 arranged in collar 27. 
     This device operates in the same way as the one described with reference to FIG. 2, except that the fluid from the exhausting chamber comes in above the piston after flowing through said piston&#39;s center bore 53. 
     FIG. 9 shows a device having a piston 59 connected to a valve 60 by means of a stem 61, said valve being held in its seat, in closed position, by a spring 62 housed in a compartment 63 provided in a plug 64 engaged in body 7 and having a threaded portion 65, said latter portion mating with a tapped hole in a collar 66 mounted rotatively but captively, due to a rib 67 engaged in a groove in body 7. 
     This feature makes it possible to axially move plug 64 by turning collar 66, so as to adjust the compression of spring 62 for purposes of adjusting fluid flow and the speed of the cylinder piston. 
     Collar 9 is provided with a ball check valve 68 making it possible to vent the space above valve 60. 
     When chamber 1a of the cylinder (FIG. 1) is supplied with fluid, valve 60 is in open position, piston 59 being pushed up against spring 62 by the pressure of the fluid exhausting from chamber 1b of the cylinder, which enters chamber 69 through pipe connection 26. 
     As soon as the pressure of the exhaust fluid disappears, as the piston 2 of the cylinder 1 reaches the end of its stroke, piston 59 returns to its initial position by the action of spring 62 and valve 60 closes. 
     Check valve 20 enables bypassing of valve 60 to allow fluid to pass in reverse when cylinder chamber 1a is in the exhausting phase. 
     The device illustrated in FIG. 10 is analogous to that of FIG. 9 except for the body 70 which comes in a single unit and has two pipe connections 71, 72 which are axially aligned with one another for insertion into a pipeline. 
     Moreover, connection with the fluid exhaust line is made via a pipe 73 issuing into chamber 69 of body 70. 
     FIG. 11 shows another embodiment of an economizing device whose valve is controlled to close by a pressure signal sent by an end-of-stroke detector on piston 2 of cylinder 1 or by any other suitable means providing a pressure signal. 
     This device includes a plug 22 with a threaded part 74 screwed into body 7, on which body is mounted at a right angle, by means of a collar 9, a pipe connection 10 containing a check valve 20. Plug 22 contains a cavity 75 in which is slidably mounted a piston 76 spring loaded by spring 77 and fitted with a closing member 78 on one of its ends forming the valve which closes against a seat 79 provided in the body between ducts 15 and 18. 
     The top of plug 22 is provided with a bore hole 80 connected to a pressure signal means,in particular to signal the end of the stroke of the cylinder piston. 
     When driving fluid is applied to the base of valve 78 said valve is pushed against the force of spring 77 and opens to allow the fluid to flow out through duct 18 and cylinder chamber 1a. If at a given time a pressure signal is sent via borehole 80 into cavity 75, the pressurized fluid, together with spring 77, act on piston 76, closing valve 78, which applies against the seat 79, thus cutting off the flow of driving fluid. 
     FIG. 12 shows an economizing device having a valve controlled by a pressure signal. A piston 81 and valve 82 unit is fitted in the body 7 such that the valve is kept open by a spring 83. 
     The top of body 7 is provided with a plug 84 having a threaded part 85 by which it engages in a tapped hole in an adjusting ring 86 having a circular rib 87 mating with a groove in body 7, said ring thus being rotatably maintained on body 7. This feature enables adjustment of valve 82 in relation to its seat when it is opened and, following, adjustment of the rate of fluid flow and of the speed of cylinder piston 2. 
     The top part of plug 84 has a center bore 88 enabling transmission of a pressure signal to piston 81 to close valve 82 against the action of spring 83 at a predetermined time, particularly when the cylinder is at the end of its stroke. 
     FIG. 13 shows a device like that of FIG. 12, except that it lacks a spring 83, due to the face that the chamber 89 is vented to the atmosphere via a duct 90. 
     FIG. 14 shows a device similar to that of FIG. 12 wherein the pressure signal however enters laterally. 
     To this effect, the device is provided with another pipe connection 91 above pipe connection 10, said connection 91 comprising a collar 92 fitted to body 7 and provided with seals 92a and 92b for the purpose of isolating an annular space between the body 7 and the collar 92, said annular space connecting pipe 93 via an aperture 94 to a chamber 95 located above piston 81. 
     The pressurized fluid corresponding to a signal can thus propagate from pipe 93 to chamber 95 wherein it acts upon the piston 81 and against the action of spring 83 and closes normally-open valve 82. 
     The device shown in FIG. 15 is the same as that of FIG. 14, except for the arrangement of body 96 which has two pipe connections 96a and 96b axially aligned with one another, said pipe connections ensuring the flow of fluid in one direction by valve 82 or in the other direction by means of check valve 20. 
     The device shown in FIG. 16 is the same as that of FIG. 8, except that it is used in the case of a piston operated by a pressure signal. 
     To this effect, collar 27 is flipped over so that the slanted duct 50 issues into annular space 56 and, via aperture 55, into chamber 54a under piston 44. Also, as space 51 is vented to the atmosphere via the aperture 58 in collar 27, it is possible to vent space 54 via center bore 53, which issues into annular space 51. 
     When a pressure signal is fed through pipe 28, duct 50, space 52 and aperture 55 to chamber 54a, piston 44 moves up against spring 46 such that valve 30 is pushed up by spring 33 to close off the passage between ducts 15 and 18. 
     The invention is not limited to the embodiments shown and a person ordinarily skilled in the art may make some modifications to it without departing from the scope of the invention.