CS201233B1 - Driving mechanism of the mechanical tachometer of the spark ignition piston engine - Google Patents

Description

The invention provides a drive mechanism for a mechanical tachometer of a positive-ignition piston engine with an ignition-controlled mechanical breaker.

Various drives of the mechanical tachometer of spark-ignition piston engines are known. The most common is the drive from the crankshaft or camshaft of the engine by means of an angular gear and a flexible shaft. There are also known cases where a special auxiliary transmission is provided for the tachometer drive, or where this auxiliary transmission is combined with the timing or ignition mechanism drive. In some engines, the drive of the mechanical tachometer was also driven by an oil or water pump, a fan, or even in some cases by a separate power source.

All known methods of mechanical tachometer drive are disadvantageous, because separate gearbox for tachometer drive means complication and price increase of the engine, direct crankshaft transmission in modern high-speed engines is disadvantageous for considerable speed of flexible shaft and combination of tachometer drive with other aggregate . Of the solutions used hitherto, the output for driving a mechanical tachometer away from the camshaft has proven to be the best, but this solution is feasible only in some four-stroke engine designs.

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The aforementioned drawbacks are overcome by the mechanical tachometer drive device of the invention, which is based on the fact that in the inner part of the breaker cam body there are driving surfaces for the extension of the flexible shaft of the mechanical tachometer drive.

In this case, only one drive device is common to drive both the mechanical tachometer and the mechanical electric breaker. The drive of the mechanical tachometer from the interrupter cam advantageously uses a gear reduction to half the speed of the crankshaft in four-stroke engines; By suitable arrangement it is possible to significantly improve accessibility to the breaker or even advantageous outlet of the flexible shaft without major bends, both for motorcycles and cars. The device according to the invention does not interfere with the installation of a centrifugal and vacuum advance regulator, which does not affect the operation of the tachometer. The use of the inner part of the cam body to provide entraining surfaces for the flexible shaft extension results in easy disassembly with minimal dimensional requirements.

The attached drawing shows a schematic cross-section of the crankshaft and the drive device.

The crank shaft 2 is rotatably mounted in the engine housing 1, at the end of which there is a gear drive wheel 6 for driving the ignition and the tachometer. The drive wheel 6 engages a driven wheel 6 mounted on the shaft 6 of the circuit breaker 6. A cam 5 is formed on the shaft 6 which contacts the unmarked arms of the primary electrical breaker. In the housing part of the cam body 8, there are formed driving surfaces 8 into which the abutment surfaces 8 of the extension 10 fit. The extension 10 is firmly connected to the flexible shaft 11 leading to an unmarked tachometer.

Upon rotation of the crankshaft 2 with a drive wheel engages with the idler wheel £ 4 and the shaft rotates and thereby £ £ breaker is in operation, ^t dip driving surface 8 and the corresponding support surfaces £ is transmitted by a mechanical rotational movement of the flexible shaft 11 to a tachometer. In order to eventually disconnect the tachometer drive, it is sufficient to remove the extension 10 from the cam body. The interrupter is easily accessible.

Claims (1)

A mechanical tachometer engine of a positive-ignition piston engine with an ignition-operated mechanical interrupter with a rotary cam which is driven by a gear mechanism, characterized in that in the inner part of the cam body (7) of the interrupter (6) 11) mechanical tachometer drive.