Pilot Adjuster-Connector for Adjusting the Speed of Pneumatic Pressure Cylinders

The invention relates to apparatus in which the speed of a double-acting pneumatic cylinder is adjusted for each travel direction by means of a unidirectional flow limiter placed between the orifice of the pressure cylinder through which the air escapes during the adjusted stroke and its directional control valve. Such an apparatus, also called adjuster, comprises an adjustment screw fast with a needle-valve for limiting at will the flow of air escaping through its seat which thus determines the speed of the cylinder. So that, in the other travel direction, the drive fluid is admitted at full flow into this same chamber, the adjuster further comprises a unidirectional valve opening in the direction of the intake flow and closing in the direction of the escape flow. Conventional adjusters only allow a single adjusted speed for one travel direction of the pressure cylinder, which speed is established at the outset and remains constant. Now, in a large number of cases, it would be desirable to have, during each stroke and on demand, two speeds of different values, which would increase the operating rates while avoiding end of travel shocks, or else allowing a rapid speed of a tool to be readily obtained followed by a slower working speed.

The present invention makes it possible to attain this aim, by providing two-speed adjusters, the passage from one speed to a second adjusted lower speed being achieved by a pneumatic control signal arriving in the apparatus and the reverse operation by disappearance of this signal.

Various prior art arrangements are known including these as follows:

These patents or known prior uses teach and disclose various types of valve metering systems of various sorts and of various manufactures and the like as well as methods of their construction, but none of them whether taken singly or in combination disclose the specific details of the combination of the invention in such a way as to bear upon claims of the present invention.

According to the invention, a controlled connector-adjuster comprises three connectable orifices; the first orifice is connected to one of the orifices of the pressure cylinder through which the air leaves in the direction of the stroke whose speed it is desired to adjust; the second orifice is connected to the corresponding orifice of the directional control valve and the third orifice is connected to a control pipe. The air escaping from the pressure cylinder during the stroke flows from the first to the second orifice and its flowrate through a seat depends on the position of a needle-valve which controls the flow section thereof. This needle-valve is formed by the end of a piston sliding sealingly by means of a seal in its cylindrical housing and which may be subjected, on its face opposite the needle-valve, to the pressure of a signal coming from outside. This signal causes the piston to move in the direction of the seat and since this stroke is limited by the internal end of a screw which can be operated from outside against which it abuts by its needle-valve end, the flowrate of the escaping air passing through the apparatus, and so the speed of the pressure cylinder, thus depends on the adjustment of this screw. In this simplified version of the apparatus, in the absence of the control signal, the pressure passing through the adjuster in one direction or the other pushes the piston back fully into the opening of the seat and such an apparatus only allows a single adjusted speed introduced by a control signal. In preferred versions of application of the invention, the stroke of the piston on opening the seat may also be limited by a second adjustment screw opposite the first one, against which it abuts by its end opposite the needle-valve; this second screw adjusting a pressure cylinder speed always higher than that adjusted by the first one which determines the flow section through the seat in the presence of a control signal. In order then to allow full intake flow towards the cylinder during its return stroke, which flow passes through the adjuster in a direction opposite that of the controlled escape flows, a return valve is disposed to by-pass the seat and open in the direction of air intake towards the pressure cylinder and close in the direction of the bleed flow coming therefrom.

Other features and advantages of the invention will be better understood from the following description of several preferred embodiments with reference to the accompanying drawings.

FIG. 1 is a sectional view of a controlled connector-adjuster and mounting thereof for obtaining two different extension speeds of the rod of a pressure cylinder.

FIG. 2 is a section view of another embodiment of the invention also according to a preferred embodiment thereof.

FIG. 3 is a section view of another embodiment of the invention.

FIG. 4 is a section view of another embodiment of the invention.

In FIG. 1, the controlled adjuster comprises, in a body 1, a piston 2 sliding sealingly in a cylindrical housing by means of a seal 3 and one end of which forms a needle valve 15 cooperating with a seat 16 for controlling the rate of fluid flow from a first chamber 4 to a second chamber 5. The first chamber 4 is defined by its seat 16, an annular unidirectional valve 14 by-passing said seat, the seal 8 of an adjustment screw 7 and a connection orifice 11. The second chamber 5 is defined by its seat 16, valve 14, the seal 3 of piston 2 and a connectable orifice 12. Valve 14 is oriented so as to close and shut off the fluid flow from chamber 4 to chamber 5 and open in the opposite direction. The apparatus also comprises a third chamber 6 defined by seal 3 of piston 2, a plug 1a closing the housing of said piston, the seal 10 of an adjustment screw 9 in plug 1a and a connectable orifice 13.

Such as shown in FIG. 1, the controlled adjuster adjusts the low extension speed of the rod of a pressure cylinder 30 by the effect of a control signal delivered by a sensor 50. The air from the chamber of the pressure cylinder vented on the rod side, flows into the adjuster from its orifice 11 to its orifice 12, closes valve 14 to its own passage which can only take place through seat 16 with a flowrate depending on the position of needle valve 15. With chamber 6 pressurized, piston 2 is pushed in abutment against the internal end 7a of screw 7 which passes through seat 16 and penetrates into a blind axial channel of piston 2 and improves guiding thereof. In the presence of the control signal, the speed of pressure cylinder 30 is therefore adjusted by screw 7. In the absence of this signal, piston 2 is held in the open position of seat 6 by the effect of the pressure passing through the apparatus into chamber 5. The flow section left for the flow escaping through seat 16 then depends on the adjustment of screw 9 against the internal end of which piston 2 abuts by its face opposite needle valve 15. Screw 9 adjusts then a cylinder speed which is always greater than that adjusted by screw 7. With the cylinder effecting its return stroke, the intake air passing through the adjuster from orifice 12 to orifice 11 opens valve 14 and the full flow is thus ensured, whether the control signal is present or not at orifice 13 and independently of the adjustment of screws 7 and 9. Sensor 50 may be operated either manually, or by the rod of the pressure cylinder 30 itself or that of another pressure cylinder. The signal may also come from different sources, such as a timer, the start-up of another cylinder, sequencer, etc . . . It may be emitted only for some operating sequences of the pressure cylinder in the cycle.

FIG. 2 shows in section another embodiment of the invention which differs essentially from the embodiment described above in connection with FIG. 1 by its piston 2 which comprises two different sections defined by seals 3 and 3a which it carries. Seal 3a, of a larger diameter than that of seal 3, is subjected to the pressure of the signal in chamber 6; such an arrangement making it possible to use a control signal of possibly low pressure.

FIG. 3 shows in section another embodiment of the invention which, like the embodiment described above in connection with FIG. 2, comprises a stepped piston 2 movable under the effect of a low control pressure. In FIG. 3, the needle valve 15 of piston 2 is extended by a rod 2a of small diameter which passes through seat 16 and comprises at its end a piston section defined by its seal 3b which is smaller than that of the seat and that of the large section of the piston defined by seal 3. The pressure passing through the apparatus acts on piston 2 in the direction opening seat 16 with a force resulting from the difference of sections 3-3b, whereas the antagonistic pressure of the signal acts on the full section 3. In this arrangement also the adjustment screw 7 for the low speed on the internal end of which piston 2 abuts by its small section, comprises no seal.

FIG. 4 shows in section another embodiment of a controlled two-speed connector-adjuster in accordance with the invention. In FIG. 4 and conversely to the arrangement of the embodiments described with reference to FIGS. 1, 2 and 3, the arrangement of piston 2 is here such that it tends to close seat 16 in the direction of escaping air flow, namely from chamber 4 to chamber 5; this arrangement is more especially applicable in small sized apparatus.

In FIGS. 1, 2, 3 and 4, the adjustment screw 7 for the low speed comprises a left-hand thread and the adjustment screw 9 for the high speed a right-hand thread.

In FIGS. 1, 2, 3 and 4, the orifices 11, 12 and 13 are equipped with quick-fit connection cartridges 11a, 12a and 13a.

Of course, the present invention is not limitative and a man skilled in the art may make modifications thereto without departing from the scope of the invention.