US 3848470 A
A syringe type sampling valve wherein delivery is achieved by rapid drive forward of syringe piston and collection of sample is achieved by the cam controlled with drawal of the piston. The cam assures slow, usually uniform filling rate of the syringe barrel.
Description (OCR text may contain errors)
United States Patent [191 llargash et a1.
[451 Nov. 19, 1974 SAMPLE COLLECTION AND DELIVERY APPARATUS  Inventors: Paul Hal-gash, Saginaw; Franklin .1.
Karle, Midland, both of Mich.
 Assignee: The Dow Chemical Company,
 Filed: Aug. 2, 1972 21 Appl. No.: 277,318
 US. Cl. 73/4256, 23/259, 73/422 R  Int. Cl. G0ln 1/14  Field of Search 73/4254 R, 423 R, 425.6,
 References Cited UNITED STATES PATENTS 7/1959 Alm 141/130 4/1965 Anthon 23/253 R 6/1965 Peterson et a1. 73/4254 R Primary Examiner Richard C. Queisser Assistant Examiner-Daniel M. Yasich Attorney, Agent, or Firm-E. D. Ayers ABSTRACT A syringe type sampling valve wherein delivery is achieved by rapid drive forward of syringe piston and collection of sample is achieved by the cam controlled with drawal of the piston. The cam assures slow, usually uniform filling rate of the syringe barrel.
6 Claims, 2 Drawing Figures TIMER F; 7
SAMPLE COLLECTION AND DELIVERY APPARATUS BACKGROUND OF THE INVENTION This invention relates to sampling valve apparatus, and particularly to such apparatus wherein a syringe barrel and piston coupled to a suitable valving unit are used to withdraw sample from one source and then discharge the sample to another utilization line or the like.
Other syringe type sampling valve assemblies are known, but most are worn or other gear type load and discharge devices.
It is an object of this invention to provide an im proved sampling valve assembly which is adapted to a controlled sample loading rate and wherein rapid discharge of sample from the assembly may be accomplished.
OBJECTS OF THE INVENTION A further object of the invention is to provide improved sample valve apparatus wherein discharge of sample may be accomplished at any time during the sample withdrawal cycle without affecting the sample withdrawal apparatus.
STATEMENT OF INVENTION In accordance with this invention, there is provided apparatus wherein the needle end of a syringe is coupled to a sample material inlet and discharge unit. The barrel of the syringe is held in fixed position while the piston is withdrawn by the force of a spring which is first compressed by the operation of the discharge cycle drive means, usually an air cylinder, for example, driving a rod coupled to the piston.
The loading rate of the syringe barrel is controlled by the contacting of a stop element coupled to the rod against the peripheral surface of a rotating cam. Usually the shape of the cam is such that a constant barrel loading rate is achieved. As material is discharged from the barrel, the stop element leaves the cam and moves to a forward position and is held there until further cam rotation indexes with the stop element and air from air drive means for the rod element is released. Filling of the barrel then starts as the spring force withdraws the piston.
BRIEF DESCRIPTION OF THE DRAWING The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which:
FIG. 1 is a side elevational view of sampling valve apparatus in accordance with this invention, and
FIG. 2 is a plan view of the apparatus shown in FIG. 1.
DETAILED DESCRIPTION OF THE DRAWING Referring to the drawing, there is shown apparatus, indicated generally by the numeral 10, for sample material withdrawing and discharging. The apparatus is supported on and by a base plate 12 fixedly coupled to end plates 14, 16.
A syringe barrel [8 is held in a fixed generally horizontal position with respect to the base plate 12 by means of the holding block 20 which surrounds the barrel and is secured to the base plate 12.
The needle 68 is coupled between the forward end of the barrel 18 and a sample material inlet-outlet valved unit 66.
A pneumatic piston device 28 driving a rod 26 is fixedly coupled to the end plate 14 so that the rod 26 is axially aligned with the piston 22 in the syringe barrel 18. The device 28 includes a coil spring 29 surrounding the part of the rod 26 disposed within the housing of the device 28, the ends of the spring bearing respectively against the forward end of the housing and a piston 31 attached to the rear end of the rod 26.
The forward end of the rod 26 is coupled to the rear end of the syringe piston 22 by means of the coupling collar 24.
A rod-like member 36 carrying a rotatable stop or cam contacting element 33 is coupled to and extends downwardly from the collar 24. The lower end part of member 36, containing a sliding contacting element 34, rides in a slot 32 in the base plate 12. The slot 32 is aligned with andat least coextensive with the length of travel of the piston 22.
A generally cardioid shaped flat cam or cam-like plate element 38 is fixedly eccentrically coupled to a shaft 40 whose reduced diameter lower part extends through the base plate 12 and has a worm gear plate 42 coupled thereto.
The gear plate 42 is driven by the worm element 44 on rotatable shaft 48. The shaft 48, supported by bearings 46, 50 coupled to the base plate 12 and end plate 14, respectively, extends through the end plate 14 and is coupled through gears 52, 54 to a drive motor 56 which is coupled to the end plate 14.
The shaft 40 is located beneath the rod 26, the longitudinal axis of the shaft 40 perpendicularly intersecting the longitudinal axis of the rod 26. The cam-like plate 38 is positioned so that as it rotates, the cam-like plate element is aligned with the cam contacting element 33 and passes under the pneumatic piston device 28.
The cam-like plate element 38 has a rod-like indexing element 45 on its upper surface. A micro-switch 60 is secured to the base plate 12 and has its contact 61 extended over the top of the cam 38 so that it contacts the indexing element 45 each time the cam rotates. The position of the indexing element 45 is such that contact with contact 61 occurs when the edge of the cam contacts the cam contacting element 33 at the most forward position of the piston 22.
A micro-switch 62, coupled to base plate 12, has a feeler contact arm 63 extending therefrom so that the switch is actuated when the piston 22 is in its most forward position (the arm 63 contacts the collar 24).
A micro-switch 58, coupled to base plate 12, has its contact arm 59 positioned so that the switch is actuated by the forward movement of the pin 57 extending from the valved unit 66.
Air is supplied to the device 28 through tube 30 coupled to the valve 64, commonly a three way valve. Operation 7 In operation with the barrel 18 full of sample, a timer 100, a simple cam actuated timer, operates the valve 66, pushing the rod 57 outwardly to actuate microswitch 58. The closing of micro-switch 58 operates air valve 64 to supply air to the device 28, rapidly pushing the rod 26 forward to advance piston 22 and empty the barrel 18 of sample material.
As the rod 26 reaches its most forward position to empty the barrel 18, arm 63 of micro-switch 62 contacts the collar 24, actuating the switch 62 to close the valve 66, thus withdrawing the pin 57 so microswitch 58 is de-actuated.
The timer 100 is connected to a power supply 102. The electrical wires A through F of the timer 100 are shown in FIG. 2 as being connected to the corresponding wires A through F of the elements therein. The timer maintains air pressure through valve 64 on the device 28 until the rotation of the cam 38 is such that the pin 45 actuates the switch 60 which shuts off the motor 56 with the cam 38 contacting the stop element 33. The air is then released from the device 28, allowing the compressed spring 29 to tend to draw back the rod 26. The rod 26 cannot move, however, because the stop element 33 bears against the edge of the cam 38.
When sample is to be withdrawn through the closed valve unit 66, the timer starts the worm drive motor 56, causing the cam to rotate and permitting the piston 22 to be drawn back at a slow rate.
By the time the cam has rotated 180 degrees the syringe barrel is filled and the timer may then cause valve 66 to open to re-start the discharge cycle as previously described. 8
When the cam 38 has a configuration such that a constant barrel filling rate is achieved, the timer may be adjusted to fill the barrel to any predetermined amount, if desired.
The shape of the cam 38 may vary widely from tha shown. For example, as shown in FIG. 2, only the left hand lobe of the cam is used to control loading of the barrel if the cam rotates in a clockwise direction. Symmetry of the cam permits rotation of the cam 38 in either direction, however, to accomplish loading of the barrel 18.
The slow rotation of the cam 38 permits the barrel to be filled without the usual introduction of bubbles to the barrel, thus providing a uniform rate of input to the barrel.
Further, this apparatus permits the discharge of sample material at any time during the filling cycle since there is no fixed coupling between the cam 38 and the rod 26.
While a spring loaded pneumatic cylinder 28 has been described, a double acting pneumatic cylinder,
solenoid driven piston device or other suitable drive and withdrawal means may be used. The motor 56 may be chosen for any wanted operating speed. Sample vis' cosity variations may require changes in motor speed and/or gears to provide a suitable barrel filling rate.
What is claimed is:
l. Fluid sample withdrawal and discharging apparatus comprising a syringe-like hollow barrel having a close fitting piston therein, said barrel having a constricted forward end and an open rear end, said piston extending into said barrel from said rear end, means including an actuating rod-like member for rapidly driving said piston towards said constricted forward end and for withdrawing said piston away from said constricted end, a rotatable cam-like plate having an edge surface, means for rotating said cam-like plate, said cam-like plate being disposed adjacent to said rod-like member, contact means coupled to said rod-like member and positioned to bear against said edge surface of said cam as said piston is withdrawn away from said constricted end, and timing means cooperating with switching means selectively to actuate said means for driving said piston and said means for rotating said cam-like element.
2. Apparatus in accordance with claim 1, wherein said means for driving said piston forward and for withdrawing said piston comprises a spring loaded pneumatic cylinder device coupled to said rod-like member.
3. Apparatus in accordance with claim 1, wherein said cam-like plate is disposed under said rod-like member and said contact means comprises a rotatable element coupled to a rod extending downwardly with respect to and is coupled to said rod-like member.
4. Apparatus in accordance with claim 1, wherein means is provided to prevent rotation of said rod-like member.
5. Apparatus in accordance with claim 1, wherein said cam-like plate is coupled to a shaft rotatably driven by worm drive means.
6. Apparatus in accordance with claim 1, wherein means are provided for positionally indexing said camlike plate with respect to said piston when said piston is in most forward position towards said constricted