Lohmann engine
The Lohmann engine is an engine concept that was invented by Hermann Teegen in Germany and patented by Lohmann-Werke AG in 1951.
Working principle
The Lohmann engine is a multifuel - two-stroke - combustion engine with compression ignition. Its mode of operation differs from that of both gasoline and diesel engines. The intake air is mixed with fuel in what is known as the mixer, so the engine has an external mixture formation. The torque is adjusted by throttling the mixture with a slide. After pre-compression in the crankcase and overflow, the prepared fuel-air mixture is compressed in the combustion chamber to such an extent that it ignites by itself. Since the Lohmann engine does not have a preheating device, the energy required for self-ignition during a cold start must be achieved in another way. For this purpose, the compression ratio can be increased by moving the liner by hand. When the engine has warmed up, the compression is reduced again. It is also possible to adapt the engine operation to the type of fuel used. The fuel used in the Lohmann engine should be as ignitable as possible, i.e. have a high cetane number .
Bicycle auxiliary motor from Lohmann
| Lohmann | |
|---|---|
 |
|
| Lohmann add-on engine | |
| Manufacturer: | Lohmann Werke AG, Bielefeld |
| Construction time: | 1949-1954 |
| Number of pieces: | around 51,000 |
| Previous model: | - |
| Successor: | - |
| Technical specifications | |
| Displacement : | 18 cc |
| Performance : | 0.6 kW |
| Gearbox : | without circuit |
| Drive : | 1-cylinder - two-stroke - compression -ignition , driving roller |
| Empty weight : | about 5 kg |
| Top speed : | 35 km / h |
| Tank capacity : | 1.3 l |
| Fuel consumption : | approx. 1.5 l / 100 km |
The auxiliary bicycle motor from Lohmann was the first series motor to work according to the Lohmann principle in 1949. With a displacement of 18 cm 3 , it developed an output of 0.8 hp at 6000 rpm. The compression was regulated with a twist grip on the left end of the handlebar. Its actuation shifted the cylinder in the direction of its axis, whereby compression ratios from 12.5: 1 to 125: 1 could be set. During normal driving, the engine works with a compression of around 14: 1 to 18: 1. The achievable top speed was 37 km / h. It could be operated with various fuels, from diesel to kerosene. According to contemporary information, however, it was best to drive on petroleum. A ratio of 20: 1 was prescribed for the mixture of fuel and oil. On request, there were models specially modified by the factory for petrol operation, but these proved to be particularly prone to failure. In 1950 the motor cost 129 DM and the installation 3 DM. It could be attached to any bicycle. From 1953 a so-called freewheeling circuit was available, with which the drag torque of the motor could be gradually adjusted while driving. In 1956 the production was stopped; by then 51,000 had been sold. 1952-1953 the engine was also offered as a boat engine, although it was extremely unsuitable for it.
The Lohmann engine was mainly produced by Lohmann itself, for export markets also under the names Svecia and Hispania . There were licensed buildings in the Japanese city of Nagoya and from 1953 in Graz . There the engine was manufactured about 10,000 times in a much improved version and sold as a junior . Another engine that worked according to the Lohmann principle was the HAZA 25-D from Dresden. However, it was only produced on a small scale. Overall, the Lohmann engine on motor vehicles has remained an exception. It was not possible to develop the engine with good stability and to transfer the concept to larger displacements. With the disappearance of the auxiliary bicycle engines at the end of the 1950s, the Lohmann engine concept also died out.
Web links
literature
- H. Hütten, Lohmann Fahrradmotor (evaluation and criticism of the diesel engine), special edition Motor Rundschau, Stuttgart, 22/1950 (PDF file; 3.72 MB).
- Lohmann bicycle engine . In: Automobiltechnische Zeitschrift . 4/1951, pp. 78-83.
Individual evidence
- ↑ Patent specification: "Method for operating mixture-compressing, self-igniting two-stroke internal combustion engines"
- ↑ Patent specification: "Mixture compressing two-stroke internal combustion engine with adjustable compression and self-ignition"
- ↑ Dr.-Ing. Rolf-Guenther Nieberding, Diss., See 2.1.1 The Lohmann engine (PDF; 2.6 MB)
- ↑ Operating instructions Lohmann bicycle motor Type 500 , Bielefeld February 1953, pp. 3–5
- ↑ Lohmannmotoren descriptions, pictures, ABE