|Title of Invention||
AN EJECTOR MECHANISM FOR A SAMPLING PIPETTE
|Abstract||The invention concerns a pipette comprising a body and an arm mobile relative to the body to inject along a longitudinal direction of the pipette a tip fixed to the pipette, the arm comprising a first part (16, 18, 20) adapted to be urged into contact with the tip and a second part (14). The two parts are fitted one into the other while enabling to detach the first part from the body from an operating position by an initial movement along a direction essentially perpendicular to the longitudinal direction (10).|
|Full Text||A LIQUID SAMPLE TAKING PIPETTE RAVING A DETACHABLE EJECTOR
The ir.venbion relates to pipettes for taking liquid samples.
A sampling pipetee is known, e.g. from document FR-2 696 110 that is suita.ble for receiving a discardable cone at its bottom end, which cone is held on the pipetce by means of friction. The pipecte has an ejector that can be actuated by means of a button adjacent DO a sampling button. Pressing on that button enables the -cone to be pushed away from the pipecte when it: is desired no replace a used cone with a new cone.
In that pipette, the ejector has an arm with a bottom portion for coming into direct contact with the cone, and a top portion to which the bottom portion is secured by friction engagement in the longitudinal direction of the pipette. This engagement enables the bottom portion of the ejector to be assembled simply and qiiickly onto the pipette and to be removed with the same advantages, Nevertheless, while ejecting a cone, at the moment when the cone gives way and becomes detached from the Lip of the pipette, the ejector follows the cone and its speed increases suddenly- The movement of the ejector is then stopped sharply because the top portion comes into abutment against the body of the pipette. The same braking force is transmitted to the bottom portion via the friction engagement. Unfortunately, this force tends to undo the engagement between the bottom and top portions and to separate them from each other. After ejecting some number of cones, it can thus happen that the bottom portion of the ejector becomes separated from the pipette in untimely manner.
Document WO 96/37302 has a Figure 19 providing for an ejector in which the bottom portion chat pushes against the cone is itself engaged in the longitudinal direction of the pipette in a top portion of the ejector. A fixing tongue holds together the cwo interconnected
portions and prevents them from separacing in untimely manner. . Nevertheless; in order to remove the boctacn poreion, it is necessary to reach tha tongus, and that is rather awkward.
An object of the invention is to provide a pipette of a different type that avoids untimely separation of the bottom portion of the ejector, but in which the ejector remains easy to remove.
To achieve thig object, the invention provides a 'sampling pipette compr.iaing a body and an arm movable relative to the body to eject a cone fixed to the pipette, ejection taking place in a longitudinal direction of the pipette, the arm having both a first portion suitable for coming into contact with the cone, and a second portion, wherein the two portions are engaged one in the other and, starting from an operating position, they enable the first portion to be separated from the body by means of an initial movement in a direction than is.essentially perpendicular to the longitudinal direction.
Thus, because the arm still comprises two portions that are assembled together, it can continue to be removed in simple manner. Nevertheless, the invention prevents the portions separating in untimely manner under the effect of forces that ariae during ejection. In addition, since the friction connection is no longer essential, a connection can be provided than is suitable for being assembled and disassembled without applying force.
The invention may also present at least any one of the following characceristics:
- the pipette is organized in such a manner that the engagement direction is lateral;
- the pipette is organized in such a manner that there is only one engagement direction;
- one of Che arm portions is T-shaped, suitable for
being received in a correspondingly-shaped housing of the
- the pipette is organised in such a manner that the two portions can be separated from each other without previously dieassembling che pipette;
- the body of the pipette forms a.n obstacle to separating the two portions, at least when the arm lies at a high end of nhe ejection stroke;
- the pipette is organized in such a manner that the body enables the two portions to be separated when the arm lies at a low end of the ejection stroke; and ■
- the pipette includes adjustment means, enabling the lengch of the arm to be varied continuously over a range of values.
Other characteristics and advantages of the invention appear further from the following description of a preferred embodiment given by way of non-limiting example. In the accompanying drawings;
- Figure 1 is a perspective view of the ejector mechanism of a pipette constituting a preferred embodiment of the invention;
- Figure 2 is a fragmentary axial section view of the pipette showing the location of the Figure 1 mechanism;
- Figures 3 and 4 are two perspective views of the actuator of the Figure l device;
" Figure 5 is a fragmentary axial section view on plane V-v of the Figure 3 actuator;
- Figure 5A is an axial section view on plane A-A of the Figure 5 actuator;
- Figures 6 and 7 are a rear view and a left-hand view of the connection screw o£ the Figure 1 mechanism;
- Figures S and 9 are two cross-section views on planes VIII-VIII and IX-IX of the Figure 7 screw;
- Figures 10 and 11 are a perspective view and an axial section view of the ejector rod of this Figure 1 mechanism;
- Figurs 12 ia a plan view of the Figure 10 ejector rod; and
- Figure 13 is a diagram showing how the ejector rod ia put Into place on the pipette.
The sampling piperte constituting the present invention of the invention is of the same type as that described in document FR-2 696 IIG. Reference should therefore be made to that document for various details of the pipette already disclosed therein. Only certain aspects of the cone ejector mechanism are described in derail below,
With reference to Figure 2, the pipette 2 conventionally comprises a body 2 serving as a handle for holding in the uaer's hand. The pipette has a piston 6 that is slidably movable along a longitudinal axis 10 of the pipette in a bottom cavity of the pipette in order to suck uo a volume of licraid that is to be taken into said cavity, or else to expel it therefrom. Displacement of the piston is controlled in particular by means of a control rod on the axis 10 having its bottom portion connecned to the piston by parts of known type. At its top end, the rod ia surmounted by a pushbutton that 13 rigidly fixed to the rod and that the user can actuate with the thumb of the hand holding the pipette - The pisnon thus moves down and up as a function of the same movement; of the button. The pipette includes a return spring suitable for returning the piston and the rod to the high position at. the end of their down stroke for expelling liquid, and a purge spring whose effect ia added to that of the preceding spring when the stroke of the piston is continued downwards for a purge stroke.
The pipette has a bottom tip 7 suitable for receiving a discardable sampling cone 9 in conventional
manner, which cone is held by friation acting on the outside of the bottom tip.
The pipette has a cone ejector mechanism as shown in Figures 1 and 2. This mechanism compriaaa, going downwards along the longitudinal direction of the pipette; a control button 12/ an actuator 14; a connection screw 16; a knurled wheel 18;.and an ejector rod 20. The Figure 1 ejector mechanism extends over the rear portion of the pipette, i.e. the portion beside the palm of the user's hand,
The actuator 14 is generally elongate in shape in a downward direction and in capers downwards. It is received in the body 2 of the pipette so as to be slidably movable therein along the axis 10. The pipette is arranged in such a manner that downward pressure on the burton 12 causes the actuator 14 to move down. The connection between the button and che actuator can be of conventional type and is not described herein, A return spring 2 0 shown in Figure 2 serves to raise the actuator 14 when force is no longer applied no che burton 12.
With reference Co Figures 3, 4, 5, and 5A, the actuator 14 presents a bottom end formed by a female coupling portion 22. This portion is shaped in a direction parallel to the axis 10 and has a generally U-shaped cross-section, and more precisely a croas-section in the form of a portion of an ellipse with both limits 24 of che U-shape extending towards each other at both ends. The opening 2S of the U-shape faces sideways, in this case cowards the left-hand side of the pipette. The bottom edge of the coupling portion 22 has a shoulder forming a atep 2B projecting radially towards the inside of the U-ahape, Nevertheless; this shoulder is also U-ahaped. Each limb 24 is separated from the remainder of che actuator by a horizontal notch 3 0 extending from a point situated about halfway along the length of the branch to che free end thereof- The coupling portion forms a cavity 32 between the limba 24.
With reference to Figures 6 to 9, the connection screw 16 has a top head 34. The head 34 includes a support 36 generally in the form of a rectiangular parallelepiped and a male coupling portion 38 suitable for penetrating into the female coupling portion 22 of Che actuator. For this purpose, the male coupling portion 33 is of constant section parallel to the axis 10, while transversely to said axis it is generally of elliptical shape. The connection screw 16 has a core 40 from which the support 3 6 projects upwards, being offset laterally relative there to. The height of the male portion 3 8 ia less than the height of the support 36. The top ends of the male portion 3S and of the support 3 6 are at the same level, but the male portion liea at a distance from the core 40 so as to enable the step 2a to' paas between them. The male portion 3B extends towards the right, projecting from the support 36, and also towards the front and towards the rear. Seen from the left and from the right it presents a T-shaped profile.
The male portion 3 3 is suitable for being received by being engaged in the female portion 22 in a lateral direction perpendicular to the axis 10. During insertion, the limbs 24 spread apart and then move back towards each other, thereby producing a click indicating that: the male portion has reached its reception position. The limbs are capable of bending because of the notches 30 and because of the material used, which in this case is a thermoplastic material. The step 28 takes up position between the male portion 33 and the core 40. The connection screw 16 is thus rigidly assembled to the actuator 14. This assembly can be disassembled. Assembly and disassembly are performed by moving the screw in translation relative to rhe actuator in a left-right lateral direction.
The core 40 of the connection screw has a that top plate 42 and a thin bottom portion 44 of essentiallv
rectangular section. At its bottom end it is extended by a threaded rod 46.
With reference to Figures 10 ti 12, the ejector rod 20 is elongate in shape in the vertical direction. Ita transverse section is essentially hollow and open. Nevertheless, this section is closed at. the bottom end 48 of the rod in order to form a ring that is engaged alidably on a bottom endpiece SO of the body 2 forming its bontom end 1, aa shown in Figure 2. The ring is suitable for coming directly inno contact witin the cone in order to eject it. In addition, the rod 20 is essentially non-rectilinear in shape BO as to unite said bottom end 48 lying on the axis 10 of the pipette v;ith the rear portion of the pipette at the top end of the rod which is cff-center relative to the axis 10.
At its top end, the rod presents a top vertical duct 52 of rectangular cross section extending from a top face 54 of the rod to a notch 56 cut horizontally into the rod from its rear face and going towards its front face. Beneath the notch, the rod has a bottom duct 58 coaxial with the top duct 52, but this time of circular cross section. The diameter cf the bottom duct 53 is equal to the width of the profile of the top duct 52, and likewise the diameter of the threaded rod 46 of the screw 16 is equal' to the width of the bottom portion 44 of the. support,
The knurled wheel 18 has a central threaded duct to form a screw-and-nut connection with the rod 46 of the acrew 16.
The wheel 18 is received in the notch 56 in alignment with the ducts 52 and 53. The screw 16 penetrates into both ducts and also into the wheel. The male portion 38 projects from the top face 54, with the rectangular portion 44 of the support being received in the top duct 52, thereby preventing the rod 2 0 from turning relative to the screw while allowing nhem to slide relative to each other. The wheal 18 forma a
screw-and-nun connection with the rod 46 or tne screw, The bottom portion o£ the screw is slidably received in the bottom duct SB. The rod 20 is thus connecced to the pipezte firstly by the connection screw 15 and secondly by the ring 4B engaged on the endpiece.
The wheel 18 is directly accesaible to the user from behind the pipette through the notch. Turning the wheel causes the rod 20 to slide up or down relative to the body 2 parallel to the axis 10, thereby adjusting its position as a function cf the type of discardable cone
In order to eject a cone, the button 12 is lowered 3o as to bring the rod 20 to the bottom end of its stiroke, thereby pushing the cone do^^Tiwards and detaching it from the pipette.
When the ejector mechanism is at rest, i.e, at the top end of ita stroke, the male and females portions' 3 3 and 22 are received inside the body of the pipette and they are inaccessible to the user. In addition, they are protected therein against impacts and against: dirt. The rod 20 cannot be removed while in this position.
In order to remove the rod 20 and separate it from the pipette, the button 12 is lowered so as to place the rod in its bottom end of stroke position. The male and female portions are then, visible. The rod 20 is then pushed sideways to separate the male and female portions as described above and as shown in Figure 13, This causea the rod 20 to tilt ■ relative to the body of the pipette, with such tilting being possible because of clearance at the ring 48, The bottom portion of the rod is then slid downwards so as to disengage it from the pipette. Reassembly is performed by following the same operations in reverse order. The rod 20 can be assembled and removed without applying force, unlike the longitudinal connection obtained by friction in the prior art .
It can thus be seen that the rod 20, the knurled wheel 19, and the screw 16 conanitute a first portion of the ejeccor arm suitable for being engaged laterally in the second portiorx of the arm as formed by the actuator.
It should be observed that the rod can also be removed under such circumstances by turning the wheel until it becomes disengaged from the connection acrew 16. However that would separate the rod 20, the screw 16, and the knurled wheel IB from one another, whereas the procedure described above keeps these three parts connected together.
Because of the step 28, the rod 2 0 cannot be separated from the actuator 14 by sliding parallel to the axis 10. It is necessary to begin by imparting relative movement in a lateral direction. There is thus no likelihood of untimely sepairation occurring while ejecting a cone.
The knurled wheel 18 serves to adjust the length of the elector arm constituted by the actuator 14 and the rod 20 over a known range of length values.
Naturally, numerous modifications could be applied to the invention without going beyond the ambit thereof.
For example, the rod 20 could be connected to the actuator 14 by connections of other types that impede relative sliding between these parts of the ejector, -for example one or more screw-and-nut connections or a bayonet the connection.
The characteristics enabling the length of the arm to be adjusted over a known range of values can be implemented independently of the characteriatics relating to the arm being made up of two portions that are. engaged one in che other and that can be separated in a direction that is perpendicular to the longitudinal direction.
1. A sampling pipette comprising:
(a) a body; and
(b) an ejector arm attached to the body, the ejector arm comprising an ejector rod and an actuator cormected to the ejector rod, wherein the ejector rod and the actuator are engaged one in the other such that the ejector rod and the actuator may be separated by moving the ejector rod sideways with respect to the actuator,
2. The sampling pipette of claim 1 wherein the ejector rod can be separated from the actuator without removing the actuator from the body.
3. The sampling pipette of claim 2 wherein the ejector rod can be separated from the actuator only when the ejector rod is at the bottom end of a purge stroke.
4. Tlie sampling pipette of claim 1 wherein the ejector rod and the actuator can be assembled in only one direction.
5. The sampling pipette of claim 1 wherein the cormection between tlie actuator and the ejector rod comprises a connection screw.
6. The sampling pipette of claim 5 wherein the ejector rod comprises a vertical duct for housing the connection screw.
7. The sampling pipette of claim 6 wherein the ejector rod further comprises a ring capable of slidable engagement with an endpiece of the body.
8. The sampling pipette of claim 1 wherein the connection between the ejector rod and the actuator comprises a male-female connection.
9. The sampling pipette of claim 1 wherein the connection between the ejector rod and the actuator comprises a bayonet-type connection.
10. A sampling pipette comprising:
(a) a body:
(b) an ejector arm attached to the body, the ejector arm comprising an ejector rod and an actuator engaged one in the other through a connection, wherein the connection comprises a sideways facing generally U-shaped portion and a male portion adapted to be received in a lateral direction by the generally U-shaped portion.
11. The sampling pipette of claim 10 wherein the generally U-shaped portion comprises a bottom edge comprising shoulder forming a step projecting radially from the inside of theU-shape.
12. The sampling piperte of claim 10 wherein the male portion is disposed on a T-shaped connection screw.
13. The sampling pipette of claim 12 wherein a support connects the T-shaped connection screw and the male portion.
14. The sampling pipette of claim 13 wherein the T-shaped connection screw comprises a core and a threaded rod.
15. The sampling pipette of claim 13 wherein the threaded rod is screwed into an opening in the ejector rod.
16. The sampling pipette of claim 10 wherein the generally U-shaped portion comprises limbs that spread apart to accept the male portion.
17. The sampling pipette of claim 10 wherein the generally U-shaped portion
and the male portion are constructed from thermoplastic material.
18. A detachable ejector for a liquid sample pipette, the ejector comprising a connection screw threaded into an ejector rod through a knurled wheel, wherein the ejector rod is capable of reversible assembly with a pipette body.
19. A sampling pipette, substantially as herein described with reference to the accompanying drawings.
|Indian Patent Application Number||IN/PCT/2002/1624/CHE|
|PG Journal Number||38/2007|
|Date of Filing||04-Oct-2002|
|Name of Patentee||M/S. GILSON SAS|
|Applicant Address||19 AVENUE DES ENTREPRENEURS B P 45, 95400 VILLIERS LE BEL.|
|PCT International Classification Number||B01L3/02|
|PCT International Application Number||PCT/FR2001/001071|
|PCT International Filing date||2001-04-09|