Abstract: The invention relates to a shock absorber (1), in particular for a motor vehicle, which comprises: a cylinder (2) containing a hydraulic fluid; a main piston (4) actuated by a rod (3), defining in the cylinder a first main chamber (5) and a second main chamber (6), the second main chamber containing the rod; a hydraulic fluid vessel (24); and a valve (11) placed in the flow of the hydraulic fluid between the first main chamber and the second main chamber or between the first main chamber and the vessel. The valve comprises a mobile gate (14) engaging with a seat (13), a spring (20) tending to urge the gate against the seat thereof, and a mobile valve piston (17, 78), defining a first valve chamber (18, 82) and a second valve chamber (19, 83) in the valve, said mobile valve piston being capable of compressing the spring and closing the gate.

Abstract: A damper, in particular for motor vehicle, includes a cylinder containing a hydraulic fluid, a main piston (1) actuated by a rod (3) defining in the cylinder a first chamber (2a) and a second chamber (2), the second chamber containing the rod, a hydraulic fluid reservoir (6) and a valve (10) placed in the hydraulic fluid flow between the first chamber and the second chamber, the valve including a mobile check valve (28) co-operating with a seat (30) and elements designed to press the check valve on its seat. The damper further includes filtering elements mounted (16) in parallel with the valve (10), adapted to generate a filtering control pressure acting on the check valve, the control pressure depending on the pressure differential at the inlet and the outlet of the valve.

Abstract: A damper, in particular for motor vehicle, includes a cylinder containing a hydraulic fluid, a main piston (1) actuated by a rod (3) defining in the cylinder a first chamber (2a) and a second chamber (2), the second chamber containing the rod, a hydraulic fluid reservoir (6) and a valve (10) placed in the hydraulic fluid flow between the first chamber and the second chamber, the valve including a mobile check valve (28) co-operating with a seat (30) and elements designed to press the check valve on its seat. The damper further includes filtering elements mounted (16) in parallel with the valve (10), adapted to generate a filtering control pressure acting on the check valve, the control pressure depending on the pressure differential at the inlet and the outlet of the valve.

Abstract: The invention relates to the in-service monitoring of the condition of a tire of a wheel of a vehicle. To this end it proposes a process and, in particular, a device comprising: a sensor (4) mounted on the wheel, coupling means (BVF2, BRF2) for transmitting to the vehicle indications derived from this sensor (4), and electrical energizing means (BVF1, BRF1). According to the invention, the sensor (4) is a miniature acceleration-sensitive sensor implanted in the tread of the tire or in the vicinity of the tread. The coupling means, mounted on the wheel, then transmit indications relating to the measurements made at the moment at which the tread is in contact with the ground.

Abstract: The invention relates to the in-service monitoring of the condition of a tire of a wheel of a vehicle. To this end it proposes a process and, in particular, a device comprising: a sensor (4) mounted on the wheel, coupling means (BVF2, BRF2) for transmitting to the vehicle indications derived from this sensor (4), and electrical energizing means (BVF1, BRF1). According to the invention, the sensor (4) is a miniature acceleration-sensitive sensor implanted in the tread of the tire or in the vicinity of the tread. The coupling means, mounted on the wheel, then transmit indications relating to the measurements made at the moment at which the tread is in contact with the ground.

Abstract: The invention relates to a radar device comprising two antennae fed by the same emission means, but serving reception means which are separated at least in part into two channels, followed by exploitation means. It is applied, in particular, when the antennae have substantially the same main lobe, but side lobes or scatters which are at least in part different. The exploitation means are capable of considering as a false alarm any echo received with a level below a selected threshold in one of the reception channels.

Abstract: The valve comprises a shutter (11) which cooperates with a seat (12), and a spring (13) tending to press the shutter onto the seat, so as to limit the flow rate of a hydraulic fluid passing through the valve. In order to vary the force exerted by the spring (13) on the shutter (11) as a function of the flow rate through the valve, the latter comprises a movable piston (14) on which the spring (13) bears, the movable piston being displaced in a cylinder (15) which it separates into two chambers (15a, 15b). One of these chambers is in communication with the hydraulic fluid downstream or upstream of the valve, the other chamber being in communication with an intermediate space (23) whose shutter (11) constitutes a first passage orifice and which is equipped, at a second passage orifice (24), with a restriction (25) defining a pressure drop which increases with the flow rate passing through it.

Abstract: A method for assisting terrestrial vehicle traffic involves equipping at least some vehicles with a radar system and a transponder capable of re-transmitting with selected frequency transposition any radar wave received within a predetermined frequency band. The radar system semi-continuously transmits the waves capable of measuring a distance over a range of several hundreds of meter, and the radar system receives the transposed echoes in order to carry out distance measurement thereon. It is also possible to provide certain bodies, not equipped with radar, with individual transponders which are different from those provided on vehicles.

Abstract: A shock absorber for automobile vehicle suspension comprises a cylinder containing a hydraulic fluid, a piston defining a first chamber and a second chamber in the cylinder, and a rod which extends through the second chamber and is connected to the piston. A hydraulic fluid reservoir is able to communicate with the first chamber via a restriction during a rapid compression movement. A control valve is capable of opening a fluid passage between the first and second chambers. The control valve is subject on one hand to the pressure of hydraulic fluid in the first chamber tending to open the valve and, on the other hand, to the actions tending to close the valve, of a return spring and of substantially constant pressure of a fluid contained in a reference chamber, one wall of which is movable with the control valve. An external compensation casing, integral with the rod, grips the shock absorber in sealed manner, and the compensation casing is connected by a pipe to an external source of variable pressure.

Abstract: A shock absorber for the suspension of a motor vehicle includes a cylinder containing hydraulic liquid, and a piston attached to a rod wherein the piston defines first and second chambers within the cylinder. The second chamber contains the rod. A first flow restrictor permits fluid flow communication between the first chamber and a reservoir for hydraulic liquid. A control valve, movable from a closed position to an open position during a rapid compression movement of the piston, is provided for controlling fluid flow between the first and second chambers. A biasing spring and the pressure of a reference fluid contained within a reference chamber tend to bias the control valve closed while the pressure of the hydraulic fluid in the first chamber tends to bias the control valve open.

Abstract: To eliminate fixed echoes at the receiver of a pulse radar, incoming i-f signals are demodulated, subjected to Doppler filtering, centered and bottom-clipped to eliminate those whose amplitudes lie below a certain threshold. The centering operation and/or the magnitude of the threshold are controlled automatically as a function of the amplitude of the incoming signals as measured upstream of the Doppler filter.

Abstract: A device for processing radar signals which enable precise Doppler information to be obtained. The signals, demodulated in cartesian coordinate X and Y and then coded are converted into polar coordinate .rho. and .theta.. Then .theta. is replaced by the difference .theta.' between two successive values of .theta. received during two consecutive repetitions. The couple .rho., .theta.' is converted into cartesian coordinate X' and Y', filtered and then reconverted into polar coordinate .rho." and .theta." where .rho." represents the amplitude relative to the echo and .theta." its Doppler speed.

Abstract: A vehicle shock absorber of the hydraulic cylinder and piston type, including a control valve which, during compressive movement, limits pressure of the hydraulic fluid and thereby the damping force of the device in accordance with the rate of compressive movement above a predetermined rate. Operation of the valve may be controlled by pressure generated by obstructing the flow back to the reservoir of fluid displaced by the piston rod entering the cylinder on compressive movement, which pressure will vary in accordance with the rate of compression and consequently the rate of entry of the rod into the cylinder. A pressure control device is provided to limit the damping force during expansion of the shock absorber to thereby permit better road holding ability of the vehicle, with the relative strong damping force at the beginning of the following compressive movement acting to control oscillation of the suspended mass of the vehicle.

Abstract: The invention relates to a system for measuring the velocity of a moving object with respect to the ground as projected onto an axis, using the Doppler effect. Two signals .SIGMA. + kj .DELTA. and .SIGMA. - kj .DELTA. are produced from received signals .SIGMA. and .DELTA., k being a coefficient which depends on the velocity of the moving object and on a predetermined duration T. Measuring the difference between the phase of signal .SIGMA. - kj .DELTA. and that of signal .SIGMA. + kj .DELTA. after the latter has been delayed by duration T produces a signal proportional to the velocity sought. The invention is applicable to aerial or marine navigation systems.