Technical note and plan: self-regulating pump with accumulator (21 November 1949)

In this document

This technical note dated 21 November 1949 describes a "self-regulating pump with accumulator", typewritten by "Dact. RP" and drawn up by "PERINEAU" p. 5. It bears a handwritten annotation in red ink "Conf. Prov. II 49" and the date "21-11-49" p. 5.

Description of components

The text details three assemblies mounted on a single housing (1):

• The pump: a cam (2) actuates a piston (3) in a liner (4), returned by a spring (5); sealing is ensured by plastic seals (6, 7); a flat valve (8) with a seal (9), housed in a cage (10) and returned by a spring (11), retains the pressure p. 5.

• The self-regulator: a piston (12) pushes, via a ball mounted with clearance (14), a flat valve (15) with a seal (16), calibrated by a spring (17) "corresponding to a pressure of 140 kg" p. 5.

• The accumulator: two hemispheres (21, 22) separated by a membrane (23), a gas filling the sphere (22) as an "elastic organ", a ball (24) and a seal (25) for filling, and a valve (26) that stops the membrane at the end of its stroke p. 5.

Operation

The note explains that the clearance volume is eliminated to ensure the pump primes, with the piston (3) coming flush with the seat of the valve (8), an adjustment obtained "by the set of shims (27)" p. 5.

The calibrated valve (15) allows liquid to pass "up to 140 kg/cm²"; beyond this, it presses against its seat "for a pressure of 150 kg/cm²", obstructing the intake and causing the pump to run empty. When liquid is requested by the operating components, the valve uncovers the intake "until the maximum pressure of 150 kg/cm² is re-established" p. 5.

Page 6 provides the corresponding cross-section plan, numbered from 1 to 27, precisely illustrating each part mentioned in the text p. 6.

Context

This note is part of the preparatory work for what would become the Citroën hydropneumatic suspension, of which Paul Magès is recognised as the inventor, a system that would notably equip the future DS presented on 6 October 1955. By this date, Magès had already established the plans for differential interaction hydropneumatic suspension since February 1944 (Plans for differential interaction hydropneumatic suspension) and conducted the first tests on the 2 CV in 1946 (Notebook of the first tests of the 2 CV with hydropneumatic suspension). The principle of a membrane accumulator under gas pressure, regulated by a pump, is at the heart of this technology — but this connection is a matter of general historical knowledge here, not the document itself.

Archivist's perspective

Precisely dated to the day, this note constitutes an early technical milestone in the development of Magès hydraulic components, fitting between the 1944 plans and the industrial culmination on the DS in 1955.

The vocabulary used ("self-regulator", "accumulator", high-pressure calibrated valves) and the precision of the pressure ratings (140 then 150 kg/cm²) indicate a stage of reflection on hydraulic regulation that was already advanced p. 5.

This document likely belongs to the same collection as the Schematic diagram of the DS 19 hydraulic circuit (1949), dated the same year, and could be put into perspective with later developments such as the Principle of the hydraulic pressure regulator (7 October 1953), which delves deeper into pressure regulation on similar foundations.