US3095126A - Apparatus for dispensing a predetermined quantity of fluid - Google Patents

Description

June 25, 1963 H. WILLSHAW 3,095,125

APPARATUS FOR DISPENSING A PREDETERMINED QUANTITY OF FLUID Filed July 21, 1960 ttes This invention relates to apparatus for dispensing a predetermined quantity of fluid, and more particularly to apparatus for dispensing measured quantities of flu-id into machines of the type known as internal mixing machines, such as are used for mixing rubber with compounding ingredients.

In the mixing of rubber and like plastic materials in an internal mixing machine, such as is known as a Banbury machine, it is generally necessary for a quantity of oil or other fluid to be added to the mix. It is often necessary for the fluid to be added to the mix at a particular stage of the mixing process and in a relatively short space of time. In order to add the fluid quickly to the mix it has been proposed to use a storage tank, connected to the internal mixing machine via a valve. A measured quantity of fluid is placed in the storage tank, and the tank is pressurised by connecting it to a source of high-pressure compressed air. At the appropriate time in the mixing process the valve is opened and the fluid is blown into the mixing machine by the compressed air.

A disadvantage of the above apparatus is that, in operation, it is difiicult to prevent the compressed air from following the fluid into the mixer. If this should occur, there is a danger that some of the fluid together with some of the compounding ingredients, such as carbon black, may be blown out of the mixer by the compressed air.

According to the invention, apparatus for dispensing a predetermined quantity of fluid comprises a cylinder having a closed end, the cylinder being provided with an inlet valve and an outlet valve, a piston slidable within the cylinder in fluid-tight engagement therewith, means for supplying a predetermined quantity of fluid to the cylinder through the inlet valve, a connection for applying pressure to the piston .to eject the measured quantity of fluid through the outlet valve, and means for opening and closing the outlet valve.

In a preferred form of the invention an internal mixing machine is provided with apparatus for dispensing a predetermined quantity of fluid as defined in the preceding paragraph. ,i

Preferably the means for supplying a predetermined quantity of fluid to the cylinder comprises a tank having a liquid supply valve for allowing a predetermined quantity of liquid to be fed to the tank, a fluid supply valve for connection to a source of fluid pressure and an outlet for connection to said cylinder inlet valve. The predetermined quantity of liquid may be measured in terms of either volume or weight.

Preferably also, the cylinder is fluid-tightly sealed at its end remote from the outlet valve, and the connection comprises a valve, connected to the cylinder at the end remote from the outlet valve, for connection to a source of fluid pressure.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic sketch, partly in cross- 3,fl95,l25 Patented June 25, 1963 section, showing the general arrangement of apparatus for dispensing liquid to an external mixing machine;

FIGURE 2 is a cross-sectional side view of part of the apparatus shown in FIGURE 1.

A rigid steel cylinder 1, having its ends closed by steel end plates 2 and 3, is connected by means of an axially extending steel pipe 4, fluid-tightly attached to the end plate 3, to the mixing chamber 5 of an external mixing machine. The pipe 4 is fluid-tightly attached at its end 4a to the wall 6 of the mixing chamber 5 and carries, at the end 4a, a rotary plate outlet valve 7 for alternatively allowing communication between the cylinder 1 and the chamber 5 of the mixing machine or for sealing said chamber 5 from said cylinder 1.

The rotary plate outlet valve 7 is operable by means of a rod 8 attached to the outlet valve 7 at one end, passing axially through the cylinder 1, and rotatably supported in a bearing 9 at the centre of the end plate 2, the bearing 9 being provided with a fluid-tight gland 10. The end 8a of the rod 8 extends beyond the end plate 2 and is provided with a half-coupling 11a connected to a second half-coupling 11b attached to a shaft 12 supported coaxially with the rod 8 in bearings 13 and 14 carried in a framework 15 attached to the end plate 2 of the cylinder 1 by pillars 16. A pinion 17 is attached to the shaft 12. The pinion 17 is engaged by a rack 18 operatively attached to the piston of a double-acting pneumatic cylinder and piston assembly 19 mounted with its axis at right angles to the shaft 12 on the framework 15.

The cylinder 1 is provided with a steel piston 20 which is slida-ble in fluid-tight engagement with the walls of the cylinder 1 and with the rod 8. The piston 20 is provided with an axial extension 21 for projecting, when the piston is at the end of the cylinder adjacent to the mixing machine, into the pipe 4, and is of such dimensions as to leave only a small clearance 'between its outer surface and the inner surface of the said pipe when in this position'. tween the piston 20 and the rod 8 by screw-threaded bushes 24 and 25 respectively, are provided fluid-tightly to seal the piston to the rod and sealing rings 26 and 27 are provided fluid-tightly to seal the piston to the cylinder 1. s

The end plate 2 of the cylinder -1 is provided with a pipe '28 (see FIGURE 1) for connection to a compressed air line 29, through a 4-Way solenoid-operated valve 39' which is also connected via pipes 31 and 32 to actuate the double-acting pneumatic cylinder and piston 19. A nonreturn inlet valve 33 is mounted on the end plate 3 to allow liquid to pass into the cylinder and for preventing liquid from escaping therefrom The cylinder is provided with a jacket 34 (see FIGURE 2) containing electrical heating coils (not shown) to maintain liquid contained in the cylinder at a suitable temperature to enable it to flow freely.

A storage tank 35 is provided with an outlet tap 36 connected by a pipe 37 to the non-return inlet valve 33 to allow liquid to be fed from the tank into the cylinder. The storage tank 35 is also provided with an inlet 38 having a tap 39 and a non-return liquid supply valve 41 so that a measured quantity of liquid may be poured into the tank 35 from a weighing machine (not shown). The inlet tap 39 may be closed, and the space in the tank 35 above the liquid to be conveyed to the cylinder may alternatively be pressurized or connected to atmosphere by means of a pipe 41 connected to a 3-way solenoid-operated fluid pressure supply valve 42. The fluid pressure supply valve42 is connected to a compressed air line 43 and to atmosphere via pipe 44. The storage tank 35 is Sealing rings 22 and 25, held in compression be-- provided with electrical heating coils (not shown) around its outer surface, and the pipe 37 is lagged.

The operation of the apparatus described above is as follows:

A weighed quantity of liquid is allowed to flow into the storage tank 35, the outlet tap 36 being closed and the 3-way fluid pressure supply valve 42 being in a position allowing communication between the interior of the tank 35 and atmosphere. The inlet tap 39 is then closed and the 3-way fluid pressure supply v-alve 42 is operated to connect the storage tank to thecompressed air line 43.

When it is desired to charge the cylinder :1 with liquid, the 4-way solenoid-operated valve 30 is operated to 'open the pipe 28 to atmosphere, the rotary plate outlet valve 7 being in the closed position. The outlet tap 36 on the storage tank 35 is then opened. The pressure in the storage tank drives the liquid through the non-return inlet valve 33 into the cylinder and forces the piston 20 towards the end of the cylinder remote from the mixing chamber 5.

When it is desired to inject the liquid in the cylinder into the mixing machine, the 4-way solenoid valve 30 is operated to admit air pressure through the pipe 28 to the space between the piston 20 and the end plate 2. The solenoid valve 30 also applies pressure via the pipe 32 to cause the pneumatic cylinder and piston 19 to operate the rack 18 and pinion 17 to turn the axially extending rod 8 and thus the rotary plate outlet valve 7, to open the outlet valve 7 to allow the liquid to be injected ino the mixing chamber 5. During this operation, the non-return inlet valve 33 is automatically closed by the liquid pressure, and the axial extension 21 to the piston 20 projects into the pipe 4 connecting the cylinder 1 to themixing machine to ensure that only a negligible proportion of the liquid remains in the pipe 4 after the injection operation. After injection of the liquid into the mixing chamber 5, the 4-way solenoid-operated valve 30 is operated to connect the pipes 28 and 32 to atmosphere and to apply air pressure via pipe 31 to return the piston of the pneumatic cylinder and piston to its previous position, thus causing the rotary plate valve to close. I

The measurement of the quantity of liquid to be injected may alternatively be made by use of the following apparatus (see FIGURE 2);

A limit switch 45 is fixed to the end plate 2 of the cylinder 1 to be operated by a spring-loaded plunger 46, the end 46:: of the plunger 46 being arranged to be contacted and forwd towards the switch 45 by the piston 20 when a desired quantity of liquid has been admitted to the cylinder.. 7

The limit switch 45 may be connected to means for operating the tap 36 to cut off the intake of liquid when a predetermined volume of liquid has been taken into the cylinder. The quantity of liquid taken into the cylinder in this case is determined by the position of the piston when the limit switch operates, and this position may be adjusted by, for example, varying the length of the plunger 46.

The apparatus according to the invention has the advantage, when used in conjunction with an internal mixing machine, that no air is allowed to enter the mixing chamber of the mixing machine. It provides a quick and accurate method of injecting measured quantities of liquid into the mixer.

A further advantage of the apparatus according to the invention is that it is particularly suitable for use in fully automatic mixing systems, e.g. systems controlled by cycle controllers, punched cards or tape.

Having now described my invention-what I claim is:

1. Apparatus for injecting a measured amount of material into a mixing chamber comprising, a cylinder having at a delivery end an inlet for material and a delivery extension of smaller diameter than that of said cylinder having one end open to said cylinder and extending from said delivery end axially of said cylinder and having at its other end an outlet to deliver material to the mixing d chamber, a piston in said cylinder slidable fluid-tightly therein axially toward and from said delivery end, an extension of said piston extending axially of and toward said delivery extension and positioned to extend into said delivery extension towards the outlet thereof when said piston moves forwardly towards said delivery end of said cylinder on a forward delivery stroke of said piston, said piston extension beingwithdrawn clear of said delivery extension and into said cylinder to permit free flow of material from said cylinder into said delivery extension on the return stroke of said piston, an outlet valve on the outlet of said delivery extension to close said outlet, fluid actuated means to open and close said outlet valve and means to admit pressure fluid to the opposite end of said cylinder and simultaneously to said fluid actuated means to open said valve on the forward stroke of said piston and alternatively to exhaust pressure fluid from said opposite end of said cylinder and to reverse the supply of pressure fluid to said fluid actuated means to close said outlet valve on the return stroke of said piston.

2. The apparatus of claim 1 in which said delivery extension and said extension of said piston are coaxial with said cylinder and piston.

3. Apparatus for injecting fluid material into a mixing chamber comprising, a material feeding cylinder having at a delivery end a delivery extension and an inlet, said delivery extension having an inlet end from said cylinder and having at the other end an outletfor connection to a mixing chamber, a supply tank having a delivery conduit to said inlet, a non-return valve in said inlet, a piston slidable axially in said cylinder and having an extension positioned to extend into the inlet end of said delivery extension and to be disposed between the inlet end and outlet thereof when said piston is at the limit of a forward movement towards the outlet of said cylinder and to be clear of said inlet to permit free flow of material from said cylinder to said delivery extension when said piston is at the limit of its return stroke, an outlet valve on the outlet of said delivery extension movable in one direction to close said outlet and in the opposite direction to open said outlet, at fluid actuated means operable in one direction to open said outlet valve and in the opposite direction to close said outlet 'valve and means to deliver pressurized fluid to the end of said cylinder opposite said delivery end thereof and simultaneously to said fluid actuated means to open said outlet valve and alternatively to open said end of said cylinder to exhaust and to deliver pressurized fluid to said fluid actuated means to close said outlet valve.

4. The apparatus of claim 1 in which said outlet valve is a rotary valve having a stem extending through said piston and cylinder to said fluid actuated means.

5. The apparatus of claim 4 in which said stem is coaxial with said piston and cylinder.

6. The apparatus of claim 4 in which said fluid actuated means comprises a cylinder and a piston drivably connected to said valve stem to rotate said valve-stem and valve in opposite directions to open and close said valve.

7. The apparatus of claim 6 comprising a rack drivable by said piston to reciprocate therewith and a pinion mounted on said valve stem and meshing with said rack.

8. The apparatus of claim 4 in which said means to admit pressure fluid includes a four-way solenoid operated valve.

9. The apparatus of claim 3 in which said outlet valve is a rotary valve.

10. The apparatus of claim 9 in which said rotary,

valve includes an operating stem extending fluid-tightly through said piston and the other end of said cylinder to connection with said operating means.

11. The apparatus of claim 10 in which said fluid actuated. means comprises a valve operating cylinder, a

piston slidable in said cylinder and an actuating means movable by said piston to rotate said valve stem.

12. The apparatus of claim 11 in which said actuating means comprises a rack driven by said piston and a pinion meshing with said rack and in driving connection with said valve stem.

13. The apparatus of claim 12 in which said means to deliver pressurized fluid comprises a four-way valve having an inlet, an exhaust outlet, a connection to one end of said valve operating cylinder and a connection to the other end of said valve operating cylinder and to the end of said material feeding cylinder opposite to said extension.

14. The apparatus of claim 13 in which said four-way valve is -a solenoid operated valve and which comprises a limit switch to energize said solenoid having an actuating element actuated by the piston of said material feeding cylinder upon the return stroke of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,046,781 Hanford Dec. 10, 1912 1,047,492 Bowser Dec. 17, 1912 1,587,912 Lip-p et a1. June 8, 1926 1,676,425 Chapman July 10, 1928 1,784,795 Skonberg Dec. 9, 1930 2,124,073 Maclean et al. July 19, 1938 2,673,012 Harrington Mar. 23, 1954 2,908,424 Illsley Oct. 13, 1959 3,052,379 Raspante Sept. 4, 1962

Claims (1)

1. APPARATUS FOR INJECTING A MEASURED AMOUNT OF MATERIAL INTO A MIXING CHAMBER COMPRISING, A CYLINDER HAVING AT A DELIVERY END AN INLET FOR MATERIAL AND A DELIVERY EXTENSION OF SMALLER DIAMETER THAN THAT OF SAID CYLINDER HAVING ONE END OPEN TO SAID CYLINDER AND EXTENDING FROM SAID DELIVERY END AXIALLY OF SAID CYLINDER AND HAVING AT ITS OTHER END AN OUTLET TO DELIVER MATERIAL TO THE MIXING CHAMBER, A PISTON IN SAID CYLINDER SLIDABLE FLUID-TIGHTLY THEREIN AXIALLY TOWARD AND FROM SAID DELIVERY END, AN EXTENSION OF SAID PISTON EXTENDING AXIALLY OF AND TOWARD SAID DELIVERY EXTENSION AND POSITIONED TO EXTEND INTO SAID DELIVERY EXTENSION TOWARDS THE OUTLET THEREOF WHEN SAID PISTON MOVES FORWARDLY TOWARDS SAID DELIVERY END OF SAID CYLINDER ON A FORWARD DELIVERY STROKE OF SAID PISTON SAID PISTON EXTENSION BEING WITHDRAWN CLEAR OF SAID DELIVERY EXTENSION AND INTO SAID CYLINDER TO PERMIT FREE FLOW OF MATERIAL FROM SAID CYLINDER INTO SAID DELIVERY EXTENSION ON THE RETURN STROKE OF SAID PISTON, AN OUTLET VALVE ON THE OUTLET OF SAID DELIVERY EXTENSION TO CLOSE SAID OUTLET, FLUID ACTUATED MEANS TO OPEN AND CLOSE SAID OUTLET VALVE AND MEANS TO ADMIT PRESSURE FLUID TO THE OPPOSITE END OF SAID CYLINDER AND SIMULTANEOUSLY TO SAID FLUID ACTUATED MEANS TO OPEN SAID VALVE ON THE FORWARD STROKE OF SAID PISTON AND ALTERNATIVELY TO EXHAUST PRESSURE FLUID FROM SAID OPPOSITE END OF SAID CYLINDER AND TO REVERSE THE SUPPLY OF PRESSURE FLUID TO SAID FLUID ACTUATED MEANS TO CLOSE SAID OUTLET VALVE ON THE RETURN STROKE OF SAID PISTON.

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