Citroën Patent No. 832,244: electric generator with integrated hydraulic motor (1960)

In this document

This is a French patent application filed by the Société Anonyme André Citroën, under the provisional number 832,244, dated 6 July 1960 p. 118, and titled "Improvement to the drive of electric generators". The issuance is noted as "adjourned" p. 118.

The problem posed

The text starts from a classic observation: an electric generator must be driven by a motor via a mechanical coupling, which requires precise machining for centering and alignment, poses installation problems on the engine to be equipped, and requires complex regulation devices to compensate for speed variations p. 118.

The claimed solution

The invention proposes an "electric generator-drive motor" assembly where the motor rotor, driven by a pressurized fluid, is housed inside the generator stator, directly linked or incorporated into the latter's rotor (p. 119, summary p. 122). This completely eliminates "the constraints of mechanical connection between the generator and its drive motor" p. 119.

The preferred embodiment describes a piston barrel cooperating with an inclined swash plate, fed by a controlled pressurized fluid distributor (p. 120, p. 122-123). The operation is detailed: each piston subjected to pressure receives a reaction with a tangential component from the inclined plate, which drives the barrel in rotation; upon return, suction cancels this reaction p. 121.

A variant (figures 2 and 3) makes the motor variable displacement: the ball thrust bearing of the swash plate rests on a piston that allows its inclination to be varied, and therefore the power of the motor p. 120-121. The adjustable parameters are either the fluid pressure alone, or the pressure combined with the plate inclination p. 121.

The final summary p. 122 and the descriptive abstract p. 123 reiterate these four claims, associated with figures 1 (axial section of the assembly), 2 and 3 (variable displacement variant), visible in technical diagrams on pages 123-124.

Context

This patent is part of the vast hydraulic exploration work conducted at Citroën around Paul Magès, known for the invention of the hydropneumatic suspension equipping the DS (1955). At the turn of the 1960s, this expertise in pressurized fluids irrigated other engineering paths, including the driving of electric machines by hydraulic motor — a logic close to that which would give rise, a few years later, to research on hydrostatic transmission.

This type of hydraulic motor with a piston barrel and swash plate is a classic principle of industrial hydraulics, but its direct integration into the stator of a generator, without coupling, was presented as a notable simplification for vehicle installation.

Archivist's perspective

This document testifies, it seems, to a phase of diversification of hydraulic applications within the Citroën design offices, on the fringes of the better-known work on suspension. The principle of the barrel and swash plate motor, with fixed or variable displacement p. 120-121, recalls architectures that will be found later, in a form adapted for propulsion, in research on hydrostatic transmission, whose "59-74" file begins precisely at this period.

The interest of this archive lies less in its conceptual originality (the swash plate hydraulic motor is a known device) than in its specific application — integration into the stator of a generator — which illustrates the mechanical simplification approach characteristic of Magès' teams. As the inventor's name is not specified in the transcribed pages, its exact connection to Paul Magès remains a contextual hypothesis rather than a documentary fact.