Lenoir was granted a French patent FR 43624. Unfortunately the copy that can be downloaded from the German Patent Office is not very legible, especially as it is a hand-written document. Fortunately Lenoir also filed patent applications in the UK (N° 335 from 1860), Spain (N° 2140 from 1860), and the US ( US 31,722). As the US patent provides the best reproduction of the drawings I have chosen them for the illustrations.

English Patent N° 335, granted 8th Ferbruary 1860

There is also an English Patent for the Lenoir gas generator available which is in printed form. It was issued to John Henry Johnson, a patent attorney, who had filed it for Jean Joseph Etienne Lenoir.

The description can be summarized as follows:

The motor is similar in its general construction and arrangement to the ordinary steam engine. The working cylinder A is provided with two slide valves T and T1 which open alternately and at the proper times the ports a, a1 and a2 for conducting the mixture of air and gas to each side of the piston as well as the ports b, b1 and b2 for the emission of the products of combustion.

The introduction of atmospheric gas takes place through the port a, which is in communication with an open nozzle.

The movement of the piston p is transmitted to the main crank shaft B by aid of the connecting rod C1 which is secured to the crank  of the main shaft. The two eccentrics D and D1 actuate the slide valves T and T1. A small pulley E imparts motion by means of a strap to the governor or regulator of the machine.

The cylinder is provided at each end upon its two covers the igniters G and G1 in communication with an electric distributer H, carried by the main driving shaft and is itself in connection with a Rhumkorff coil which is in communication with any convenient battery or generator of electricity.

In starting the engine, the piston p is first cause to travel a certain distance thereby producing a  vacuum behind it and allows air and gas to enter such void space through the ports a and a1 respectively. According to Lenoir's specification the slide T and the orifices are arranged such that the air enters the cylinder prior to the gas, so that air and gas are not becoming entirely mixed together. They will exist in the space behind the piston in distinct strata (Emphasis added). After the slide T closes the port leading to that end of the cylinder the igniter G suddenly producing an electric spark causes the gas to explodes, heating the air and its combinations, which extends considerably. The pressure produced operates upon the piston so as to force it to the opposite side of the cylinder, the residuum of the combustion or the products thereof escaping by the exhaust slide valve T1 and passage b.



The fly wheel assists the piston in its course towards the end of the cylinder and the slides T and T1 changing their positions the air and gas are introduced to the other side of the piston just at the moment that the second igniter G1 produces a spark which ignites the gas and causes the piston to return to the opposite end of the cylinder thus completing a double stroke.


 The following statement is quite interesting as we will see later in our discussion of the Otto patent N° 532:

The object of introducing a supply of air into the cylinder before the gas is allowed to enter is to neutralize the effect of the carbonic gas formed by the combustion of the first portion of the inflammable gas as the carbonic acid gas without being thus neutralized might prevent the ignition of the remainder of the inflammable gas.

Lenoir further states: I found desirable liquid or solid Hadro-Carbons may be employed in this engine for heating and expanding the air and its combinations in which case the substances from which the inflammable gases or vapours are to be obtained are placed in a small boiler and in direct communication with the escape pipe of the engine. The boiler is first heated and as soon as the hydro-carbon is converted into vapour gas, it is place in communication with the working cylinder. The vapour so produced is ignited in exactly the same manner as the inflammable gas before mentioned and similar effects will follow. 




Back ground information

Typical dimensions for a Lenoir engine with an output power of almost 1 horse power are a cylinder diameter of 180mm and a piston stroke of 300mm. A mixture of 10% illumination gas and 90% air is ignited after the piston had travelled almost half way (148mm) to the the other end. The pressure seems to have varied over a very wide range. It was further observed, that once ignited, the electric sparks had to be maintained, or the stroke would have stopped. That may be an effect of the highly diluted gas, which, once it was started, did not maintain the combustion in its own. The machine needed 500 - 600 liters water per hour to be cooled. The consumption of illumination gas was about 3 cubic meter per horse-power and hour. In addition for every horse-power the machines consumed 1 liter of oil for lubrication. Thus the Lenoir machine needs continuous attention. [1] 

More historical information on the Lenoir gas engine

The Barnett engine

The Hock Petroleum engine


[1] G. Delabar, "Ueber Versuche mit Lenoir's Gasmaschine", Dinglers Polytechnisches Journal, Vol. 180, pages 23-28.