US3620845A

US3620845A - Weston standard cells having resiliently biassing plug means

Info

Publication number: US3620845A
Application number: US830391A
Authority: US
Inventors: Ruth Friedrichs
Original assignee: Pyro-Werke GmbH
Current assignee: Pyro-Werke GmbH
Priority date: 1968-09-19
Filing date: 1969-06-04
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16
Also published as: GB1203895A; DE1796205B1; NL6906123A

Abstract

In a Weston standard cell the liquid and semiliquid electrodes are maintained in position by a plug above, and biassed towards, each electrode. Cementing resins are not needed to hold the plugs in position, and contamination of the cell is thereby avoided. The plugs may be biassed by coil springs made from glass.

Description

United States Patent inventor Ruth Friedrichs Hannover, Germany Appl. No. 830,391 Filed June 4, 1969 Patented Nov. 16, 1971 Assignee Pyro-Werke Gmbll Ihnnover, Germany Priority Sept. 19, 1968 Germany P 17 96 205.9

WESTON STANDARD CELLS HAVING RESILIEN'ILY BIASSING PLUG MEANS 9 Claims, 3 Drawing Figs.

US. Cl 136/88 01m 17/114 Field oISearch 136/88,83,

1 1 References Cited UNITED STATES PATENTS 631,044 8/1899 Heinrich 136/88 2,189,666 2/1940 Kline 136/164 2,810,007 10/1957 Tucker et a1 136/88 2,816,946 12/1957 Vincent 136/88 FOREIGN PATENTS 1,893,152 5/1964 Germany Primary Examiner-Winston A. Douglas Assistant Examiner-A. Skapars AttorneyMason, Mason & Albright ABSTRACT: In a Weston standard cell the liquid and semiliquid electrodes are maintained in position by a plug above, and biassed towards, each electrode. Cementing resins are not needed to hold the plugs in position, and contamination of the cell is thereby avoided. The plugs may be biassed by coil springs made from glass.

WESTON STANDARD CELLS HAVING RESILIENTLY BIASSING PLUG MEANS BACKGROUND OF THE INVENTION The invention relates to a standard cell (International Weston Cell) with one semiliquid and one liquid electrode. The positive electrode of these cells may consist of chemically pure mercury, while the negative electrode may consist of semiliquid cadmium amalgam.

Standard cells are cells required to produce a prescribed electromotive force. To this end it is desirable to avoid the use of extraneous substances. In addition to this, the progress of the chemical reaction must not be disturbed, as might occur, for instance, in the event of the liquid and semiliquid electrodes being displaced during transport.

Weston cells known in the present state of the art are unsuitable for transport. The electrodes may be maintained in position by porcelain plugs or slabs of cork, the porcelain plugs having a rodlike extension held in position by being set in cementing resins, but the use of these extraneous substances shortens the life of the cell.

The purpose of the invention is, by the use of relatively simple means that are cheap to produce, to ensure the portability of the standard cell as well as to give it a long life.

BRIEF SUMMARY OF THE INVENTION According to the invention there is provided a Weston standard cell, comprising one semiliquid and one liquid electrode which are maintained in position by respective plug members, and means for biassing each plug member towards its respective electrode to maintain the latter in position.

Further, according to the invention, there is provided a Weston standard cell, comprising a casing made of inert material, the casing providing a chamber for receiving electrolyte and two limbs in which are respectively situated a liquid electrode and a semiliquid electrode, plug members made of inert material and respectively positioned to maintain the electrodes in the limbs, and spring means made of inert material and operative to bias the plug members towards the electrodes.

DESCRIPTION OF THE DRAWINGS An example of a standard cell embodying the invention is explained in greater detail hereunder, in conjunction with the accompanying purely diagrammatic drawings, in which FIG. I is a side elevation of the standard cell based on the invention;

FIG. 2 is a side elevation of the insertion used in the standard cell; and

FIG. 3 is a plan corresponding to FIG. 2.

DETAILED DESCRIPTION The standard cell has a casing I, which, in the example illustrated, is l-I-shaped. The negative electrode 2 consists of semiliquid cadmium amalgam, while chemically pure mercury is used for the positive electrode 3.

Above these two electrodes are plug members, each of which, in the example illustrated, consists of a pair of discshaped members 4 and 5, separated by a layer of quartz wool 7.

Each of these disc-shaped members 4, 5 has two sealing

rims

4a and 4b, 5a and 5b respectively, from which the

central portion

4c, 5c is set back.

The disc-shaped members 4 and 5 are made of polytetrafluorethylene and are provided with holes 4d (FIG. 3). The design'of the disc members provides an elastic seal which is applied under pressure to the inner wall of the cell casing without damage to the cell.

The electrolyte 6 is introduced above the insertions.

Each of the insertions is acted upon by a coil spring 8 made of glass by which pressure is exerted and of which the end 80 remote from the plug members is fused to the casing I. By the provision of the coil spring 8 the plug members are prevented from being displaced.

The assembly of the standard cell will now be described.

To begin with, the two disc-shaped members 4, 5 are inserted under light pressure into each arm of the casing l, the layers of quartz wool 7 being introduced between the pairs of disc-shaped members 4 and 5. In this way, the two electrodes 2 and 3 are retained in place.

Before the saturated liquid electrolyte 6 (cadmium sulfate solution, for example) is introduced the top ends of the arms of the casing l are closed by melting. This must be done before the liquid is put in, as otherwise the glass cracks. Only a filler stub 1a is left open.

In the course of this melting, the bottom ends of the arms of the casing 1 may undergo expansion, which is not desirable. The result of this is that the disc-shaped polytetrafluorethylene members 4 and 5 may no longer make such firm contact with the wall in which case the electrodes 2 and 3 would no longer be firmly retained.

To prevent displacement of the disc-shaped members 4 and 5, the two glass coil springs 8 are fused to the casing l in such a way that they exert pressure on their respective disc-shaped members 4 and 5. The diameter of the two coil springs 8 is preferably such that they make contact with the outer third of the disc-shaped members 4 and 5, so that displacement in any direction is reliably prevented.

The contact pressure is made such that the disc-shaped members 4 and 5 are forced downwards by up to 2 mm. or so, should they be lifted slightly by percolation of the electrolyte 6.

Finally, the filler stub la is closed by melting.

With an International Weston Cell made in this way, safety in transit is improved. Experiments with a vibration test bench have clearly confirmed this.

The embodiment described is merely exemplary of many forms which the invention can take, and it is intended that the protection be limited only to the scope of the appended claims.

What is claimed is:

1. In a Weston standard cell comprising a casing and liquid and semiliquid electrodes, the improvement comprising slideable plug means above the semiliquid and liquid electrodes for maintaining said electrodes in position and means for resiliently biassing said plug means into contact with said electrodes.

2. A cell according to claim 1, in which said biassing means comprises a coil spring made from glass.

3. A cell according to claim 2, in which the end of said spring remote from said slideable plug means is fused to the cell casing.

4. A cell according to claim I, in which the said plug means, comprises two superposed disc-shaped members separated by a layer of quartz wool.

5. A cell according to claim 4, in which each of said discshaped members comprises a pair of discs in sealed engagement with the cell casing, said discs being separated by a reduced diameter central portion.

6. A cell according to claim I, in which holes are provided in each plug means.

7. A cell according to claim 1, in which said plug means are made from polytetrafluorethylene.

8. A cell according to claim I, in which the casing provides a chamber containing electrolyte and two limbs opening from the chamber, the plug means being respectively positioned to maintain the electrodes in the limbs.

9. A Weston standard cell including a casing, said casing comprising means defining a chamber containing electrolyte,

a first limb in communication with said chamber and containing a liquid electrode, and

a second limb in communication with said chamber and containing a semiliquid electrode,

3 4 a slideable plug in each said limb above the electrodes conwith holes, and

tained therein for maintaining the electrodes in position, a respective glass coil spring biassing each said plug into said plug comprising, contact with the respective electrode. two superposed disc-shaped members separated by a layer of 91 v9 s d sz h e WWW? v ins ramm

Claims

2. A cell according to claim 1, in which said biassing means comprises a coil spring made from glass.
3. A cell according to claim 2, in which the end of said spring remote from said slideable plug means is fused to the cell casing.
4. A cell according to claim 1, in which the said plug means, comprises two superposed disc-shaped members separated by a layer of quartz wool.
5. A cell according to claim 4, in which each of said disc-shaped members comprises a pair of discs in sealed engagement with the cell casing, said discs being separated by a reduced diameter central portion.
6. A cell according to claim 1, in which holes are provided in each plug means.
7. A cell according to claim 1, in which said plug means are made from polytetrafluorethylene.
8. A cell according to claim 1, in which the casing provides a chamber containing electrolyte and two limbs opening from the chamber, the plug means being respectively positioned to maintain the electrodes in the limbs.
9. A Weston standard cell including a casing, said casing comprising means defining a chamber containing electrolyte, a first limb in communication With said chamber and containing a liquid electrode, and a second limb in communication with said chamber and containing a semiliquid electrode, a slideable plug in each said limb above the electrodes contained therein for maintaining the electrodes in position, said plug comprising, two superposed disc-shaped members separated by a layer of quarts wool, said disc-shaped members being provided with holes, and a respective glass coil spring biassing each said plug into contact with the respective electrode.