Man Nutzfahrzeuge Ag

Dieter Wittmann

Heribert Kubis

A device for controlling an outlet valve during the engine brake mode has a hydraulic linkage between the outlet valve and the cam shaft which is controllable by a control unit. The control unit is combined with an actuation piston of a pressure source to form an integral component which is identical for each outlet valve. The actuation piston is actuated by a brake cam and actuates the working piston of the hydraulic linkage via the intermediate control unit. With the actuation piston the outlet valve can be opened during the engine braking mode in the compression stroke in order to substantially increase the braking power of the engine. The combination of the control unit with the actuation piston in the form of an integral component allows for an inexpensive manufacture because each individual outlet valve can be provided with such an identical control component. Furthermore, by eliminating long connecting lines for the pressure medium with the integral component precise control times for the outlet valve can be achieved.

Device for controlling an outlet valve in the engine brake mode

A motor brake for air-compressing internal combustion engines is provided. To improve the braking power of the engine, it is proposed to combine a motor brake having a butterfly valve to throttle engine exhaust with a motor brake where an exhaust valve, in addition to the cam drive, can be raised slightly during the exhaust stroke via a piston. With this inventive combination, braking work can be performed not only in the exhaust stroke, but also in the compression stroke, so that the braking power can be increased by about 50 to 60%, and relative to conventional exhaust brakes by about 80 to 90%, and is increased to the order of magnitude of the effective engine power.

Motor brake for air-compressing internal combustion engines

A motor brake for an air-compressing internal combustion engine is provided. A hydraulic linkage system is disposed between a cam and an exhaust valve, and communicates via a connecting line with a high-speed solenoid valve and a linkage oil compensating system of an engine lubricating-oil circuit. A control valve is disposed in an exhaust manifold of the engine and upon actuation of the motor brake partially closes off the exhaust manifold along with activation of the solenoid valve. Via the interposition of a control unit, signals of at least one sensor are conveyed to a solenoid of the solenoid valve in such a way that, upon actuation of the motor brake during a specific time interval during lifting of a valve tappet via a projection of the cam in a compression phase, the solenoid valve is closed. The time interval is derived via processing of signals of the sensor formed from the cam position and camshaft speed. The cam is divided into six sectors having a first angular range for opening the exhaust valve in an exhaust phase, a second angular range for filling a cylinder space of the valve tappet, a third angular range for initiating closure of the solenoid valve, a fourth angular range for the cam projection, a fifth angular range for reopening the solenoid valve, and a sixth angular range for emptying the cylinder space.

Growing community of inventors

Nurnberg, Germany

Dieter Wittmann