US3122281A

US3122281A - Controlled dosage syringe

Info

Publication number: US3122281A
Application number: US225693A
Authority: US
Inventors: Damgaard Laurits Gudmund
Original assignee: H Struers Chemiske Laboratorium
Current assignee: H Struers Chemiske Laboratorium
Priority date: 1961-10-06
Filing date: 1962-09-24
Publication date: 1964-02-25
Anticipated expiration: 1981-02-25

Description

Feb. 25, 1964 L. G. DAMGAARD 3,122,281 Q CONTROLLED DOSAGE SYRINGE Filed Sept. 24, 1962 INy T R.

$70M; v s

United States Patent Office 3,122,28l Patented Feb. 25, 1964 3,122,281 CONTROLLED DOSAGE SYRWGE Laurits Gudmund Damgaard, Virum, Denmark, assignor to H. Struers Chemiske Lahoratorium, Copenhagen, Denmark Filed Sept. 24, 1962, Ser. No. 225,693 Claims priority, application Denmark Oct. 6, H61 3 Claims. (Cl. 222-309) This invention relates to a controlled dosage syringe of the type comprising a cylindrical barrel, a plunger slidable in said barrel, and cooperating means mounted on said barrel and on said plunger for withdrawing the latter from its forward position in said barrel, and for adjustably limiting the movement of withdrawal.

A syringe of the type referred to serves to eject a predetermined volume of liquid, which is rendered possible by the fact that the stroke of the plunger is determined between its fully forward position in the barrel and its withdrawn position, the latter being defined by the said means for adjustably limiting the movement of withdrawal.

Syringes of the type referred to are known in which a clamping member is attached to the barrel of the syringe, said clamping member having two columns which at their other end are connected by means of a traverse carrying a set screw. Another traverse constructed with holes for the columns is attached to the head of the plunger. Tensional springs are connected between the ends of the two traverses.

While this known construction serves the purpose for which it is intended-seeing that it limits the movements of the plunger rather reliably between the end bottom of the barrel and the top of the set screw-it nevertheless suffers from certain drawbacks. Thus, the operation of the syringe is somewhat inconvenient because the set screw is located directly at the place where the thumb should preferably be applied to the head of the plunger in order to push the plunger forward. Moreover, the construction is rather stiff so that jamming of the plunger in the barrel may easily occur if the columns are not accurately parallel to the cylinder. To remedy the drawbacks of the still construction, packing material may be used in attaching the clamping member to the cylinder, partly in order to adjust the columns to the glass which in practice cannot be made with a very high degree of accuracy, partly in order to secure adequate clamping without breakage of the glass. However, the use of soft packing material has the drawback that the apparatus will not be very resistant to boiling and sterilization. The known syringe referred to is very difficult to disassemble for cleaning purposes and when such disassembling is performed, the setting of the volumetric capacity is lost so that upon reassembling the syringe, the set screw must be adjusted anew. This is a considerable drawback since setting of the volumetric capacity may sometimes be a rather complicated operation involving checking by a weighing operation, .while on the other hand frequent cleaning is in many instances required because the clearance between the cylinder and the plunger is so small that the presence of a small particle of extraneous matter may suifice to stop the movement. Owing to the stifi construction, only an expert will be capable of replacing the glass parts in the case of breakage. Finally, it is to be mentioned that it is difiicult to avoid a lopsided pull on the plunger because this would require that the springs should be of absolutely equal strength.

It is an object of the invention to eliminate the described drawbacks. To this end, according to the invention, a controlled dosage syringe of the type referred to comprises a cylindrical barrel, a plunger slidable in said barrel, a single column attached to said barrel and located in a position parallel to and spaced from the rearward extension of the geometrical axis of said valve, an operating member attached to said plunger at the rearward end thereof, said operating member having a radially extending arm constructed with a lateral notch in a position and of a size to engage around said column at a clearance, said operating member further having a looped portion extending opposite to said arm and looped rearwardly to a point in the rearward extension of the axis of said barrel, an arm extending from said column adjacent the rear end thereof to a point in the rearward extension of the axis of said barrel, a spring located in the rearward extension of the axis of said barrel and connecting said looped portion of said operating member and said arm of said column, and adjustable stop means on said column for cooperation with said arm of said operating member.

In this construction, the stop means are displaced from the cylinder axis so that they do not form an obstacle to the placing of a thumb on the middle of the head of the plunger. Moreover, it is possible by turning the plunger and the operating member attached thereto about the cylinder axis to liberate the operating member and thereby the plunger completely from the parts attached to the cylinder so that the syringe may easily be disassembled without disturbing the setting of the stop means. Owing to the clearance at which the notch of the arm of the operating member engages around the column, the plunger is freely movable relative to the cylinder within sufficient limits to permit it to adjust itself to the cylinder so as to avoid jamming, i.e. the stiffness of the known construction referred to is eliminated. Moreover, the two symmetric springs of the known construction have been replaced by a single spring located in the axis of the cylinder so that the danger of lopsidedness of the spring force acting on the plunger has been eliminated.

In a preferred embodiment of the invention, a locking member is provided which is slidable onto and withdrawable from the end of said arm of said operating member in a radial direction with respect to the barrel axis, said locking member having curved sliding faces for engaging said column in the locking position of said locking member. The said locking member serves to prevent unintentional disengagement of the operating member from the column, and at the same time the curved sliding faces of the operating member will secure smooth sliding of the arm of the operating member along the column.

Smooth and noiseless sliding of the arm of the operating member along the column may therefore be obtained, even if the column is screw threaded. It is therefore possible, according to the invention, to construct the stop means in a particularly simple and reliable manner, viz. in the form of a nut with locking nut in screw threaded engagement with the column.

One embodiment of the invention will now be described in further detail with reference to the accompanying drawing in which FIG. 1 shows the syringe in side view,

FIG. 2 on a larger scale, a section along the line II II in FIG. 1,

FIG. 3 likewise on a larger scale, part of an operating member of the syringe, and a locking member slid halfway into position on said operating member, and

FIG. 4 the locking member of FIG. 3 as viewed from the left-hand side in that figure.

In the drawing, -1 is the cylinder or barrel of a dosage syringe, and 2 the plunger of the syringe. The cylinder 1 has a collar 3 against which two discs 4- and 5 are clamped from opposite sides. A threaded column 6 is operating member along the latter.

attached to the disc 5 in a position parallel to and spaced from the rearward extension of the cylinder axis.

The plunger 2 is constructed at its rear end with a head 7 to which an operating member 8 is attached by means of a U-shaped clip member 9 which engages below the head of the plunger and is elevated from the operating member by means of a lever 10 welded to the operating member and pressed upwards by means of a screw 11. The operating member 8 has a radially extending arm constructed with a notch 12 in a position to engage around the column 6. The notch 12 has such dimensions as to engage the column 6 at a considerable clearance in a radial direction relative to the cylinder axis. The arm of the operating member is locked relative to the column 6 by means of a locking member 13 adapted to he slid onto the arm 8' of the operating member from the end thereof. For this purpose, the locking member 13 has two

guides

14 and 15 adapted to be slid onto the marginal edges of the arm 8' of the operating member, whereby one of these guides will .close the notch 12. Below the

guides

14 and 15, the locking member is constructed with curved sliding faces 16 and 17 engaging with the column and thereby securing smooth sliding of the The locking member is made from resilient material so that it is easy to slide onto the end of the arm 8' of the operating member. The locking member does not make the construction stiff since it is capable, owing to its resiliency, of following the column even if the latter is not accurately parallel to the axis of the cylinder.

Opposite to the arm '8, the operating member 8 is constructed with a looped portion 8". A spring 19 tending to .pull the plunger rearwardly relative to the cylinder is connected between the rear end of the said looped portion 8 and an arm 18 extending from the rear end of the column. The spring 19 is located in the rearward extension of the axis of the cylinder 1. On the column, a setting nut 20' with a locking nut '21 is provided in screw threaded engagement therewith. The setting nut 20 serves to obtain .an accurate limitation of the movement of withdrawal of the plunger by' engagement of the arm 8' of the operating member 8 with the bottom face of the setting nut 20.

When the locking member 13 is removed, the plunger may be rotated -in the cylinder to liberate the operating member from the column and the

nuts

20 and 21 so that the plunger may be withdrawn and removed for cleaning purposes without disturbing the setting of the nuts.

In order to obtain easy detachment of the spring connection between the operating member and the column when the plunger is to be Withdrawn, the arm 18 con-' to and spaced from the rearward extension of the geo-.

metrical axis of said barrel, an operating member attached to said plunger at the rearward end thereof, said operating member having a radially extending 'arm constructed with a lateral notch in a position and of a size to engage around said column at a clearance, said operating member further having a looped portion extending opposite to said arm and looped rearwardly to a point in the rearward extension of the axis of said barrel, an arm extending from said column adjacent the rear end thereof to a point in the rearward extension of the axis of said barrel, a spring located in the rearward extension of the axis of said barrel and connecting said looped portion of said operating member and said arm of said column and adjustable stop means on said column for cooperation -with said arm of said operating member.

2. A syringe as in claim 1, and further comprising a locking member which is slidable onto and withdrawable from the end of said arm of said operating member in a radial direction with respect to the barrel axis, said locking member having curved sliding faces for engaging said column in the locking position of said locking member.

3. A syringe as in claim 1 in which said column is screw threaded, and said stop means consist of a nut with locking nut in screw threaded engagement with said column.

References Cited in the file of this patent UNITED STATES PATENTS 2,198,666 Gruskin Apr. 30, 1940 FOREIGN PATENTS 46,042 France Feb. 15, 1936 (Addition to No. 783,520) 733,168 Great Britain July 6, 1955 984,352 France July 5, 1951

Claims

1. A CONTROLLED DOSAGE SYRINGE COMPRISING A CYLINDRICAL BARREL, A PLUNGER SLIDABLE IN SAID BARREL, A SINGLE COLUMN ATTACHED TO SAID BARREL AND LOCATED IN A POSITION PARALLEL TO AND SPACED FROM THE REARWARD EXTENSION OF THE GEOMETRICAL AXIS OF SAID BARREL, AN OPERATING MEMBER ATTACHED TO SAID PLUNGER AT THE REARWARD END THEREOF, SAID OPERATING MEMBER HAVING A RADIALLY EXTENDING ARM CONSTRUCTED WITH A LATERAL NOTCH IN A POSITION AND OF A SIZE TO ENGAGE AROUND SAID COLUMN AT A CLEARANCE, SAID OPERATING MEMBER FURTHER HAVING A LOOPED PORTION EXTENDING OPPOSITE TO SAID ARM AND LOOPED REARWARDLY TO A POINT IN THE REARWARD EXTENSION OF THE AXIS OF SAID BARREL, AN ARM EXTENDING FROM SAID COLUMN ADJACENT THE REAR END THEREOF TO A POINT IN THE REARWARD EXTENSION OF THE AXIS OF SAID BARREL, A SPRING LOCATED IN THE REARWARD EXTENSION OF THE AXIS OF SAID BARREL AND CONNECTING SAID LOOPED PORTION OF SAID OPERATING MEMBER AND SAID ARM OF SAID COLUMN AND ADJUSTABLE STOP MEANS ON SAID COLUMN FOR COOPERATION WITH SAID ARM OF SAID OPERATING MEMBER.