Patent No. 832,245 (1960): regulation of hydraulic motors with variable swash plate

In this document

This concerns the filing of patent of invention No. 832,245, in the name of the Société Anonyme André Citroën, entitled "Process and device for the regulation of hydraulic motors", with a filing date of 6 July 1960 p. 111, processed by the Office Josse, a Parisian patent firm p. 111.

The claimed principle

The text describes a process combining two successive actions: an action on the fluid pressure, "practically instantaneous" but generating a "pressure drop", followed by an action on the motor displacement, slower but which restores energy efficiency p. 111, 113.

The described device

The preferred embodiment applies to a "barrel motor with pistons and a variable-tilt swash plate" p. 112. It combines:

• a valve 1 acting on the intake or exhaust, controlled by an assembly 2 connected to the receiver driven by the motor p. 112;
• a regulator piston 6 acting on the tilt of the swash plate 5, controlled via a spool valve 8 receiving high pressure and comprising a spool 10 in antagonism with a calibrated spring 11 p. 112-113.

Four figures illustrate variants: valve on the intake (fig. 1), valve on the exhaust (fig. 2), and two variants of the distributor where the spring balances either the high pressure or only the low pressure thanks to an "auxiliary piston 19" (fig. 3 and 4) p. 112, 114.

The detailed operation is described for a decrease in resistive torque: reduction of the valve opening, displacement of the spool, venting of piston 6, straightening of the plate, reduction of displacement, then resetting of the valve "as soon as the plate 5 has taken its new equilibrium position" p. 113.

The document closes with a summary in 7 claims p. 114-116 and a descriptive abstract synthesizing the invention p. 116-117.

Context

The early 1960s correspond, in Citroën's history, to a period of active research into hydraulic transmissions, extending the achievements of the DS hydropneumatic suspension. The regulation of variable-displacement hydraulic motors mentioned here is part of the work that would lead, some fifteen years later, to the hydrostatic transmissions tested on various Citroën vehicles. These general context elements are, however, not mentioned in the document itself.

Archivist's perspective

This patent likely occupies a technical milestone in Paul Magès' research on hydraulic transmissions: it establishes, as early as 1960, the principle of a two-stage regulation—pressure then displacement—which seems to herald subsequent developments in hydrostatic transmission, as found in later documents such as the Manuscript notes "Presentation T.H. 50 CV" at the B.E.A. or the P. Magès' presentation on hydrostatic transmission.

The uneven legibility of the pages (overprints, uncertain passages) limits the complete reconstruction of the text, but the architecture of the patent—description, summary, abstract—remains clearly identifiable and consistent from one page to the next.