Apparatus for detecting rammer tip-over

An apparatus for detecting tip-over of a rammer equipped with an internal combustion engine, a crankcase accommodating an output shaft rotatably connected to the engine, a movable unit accommodating a converter mechanism for converting rotation of the output shaft to a linear motion of a movable member in a direction of the gravitational force, a tamping shoe connected to the movable unit, and a handle operable by an user, and adapted to thrust against the gravitational force by the linear motion of the movable member and go into a free fall to compact a ground surface with resulting impact force acting on the tamping shoe, comprising a pulsar coil and a microcomputer, the pulsar coil producing an output indicating a rotational speed of the engine and sending the output to the microcomputer,

• the microcomputer being programmed to:
• calculate the rotational speed of the engine based on the output sent by the pulsar coil;
• determine whether the calculated engine speed becomes equal to or smaller than a threshold value set lower than an engine idling speed when the engine has been operated at a rammer working speed set greater than the engine idling speed;
• discriminate that the rammer has tipped over if the calculated engine speed becomes equals to or smaller than the threshold value;
• and
• shut down the engine when it is discriminated that the rammer has tipped over,
• wherein, when the detected engine speed becomes equal to or smaller than the threshold value and the microcomputer discriminates that the rammer has tipped over, the detected engine speed repeats a behavior of rising toward the rammer working speed and reversing to fall toward the threshold value again until the engine shutdown unit shuts down the engine.

A method for detecting tip-over of a rammer equipped with an internal combustion engine, a crankcase accommodating an output shaft rotatably connected to the engine, a movable unit accommodating a converter mechanism for converting rotation of the output shaft to a linear motion of a movable member in a direction of the gravitational force, a tamping shoe connected to the movable unit, and a handle operable by an user, and adapted to thrust against the gravitational force by the linear motion of the movable member and go into a free fall to compact a ground surface with resulting impact force acting on the tamping shoe, comprising the steps of:

• detecting a rotational speed of the engine;
• determining whether the detected engine speed becomes equal to or smaller than a threshold value set lower than an engine idling speed when the engine has been operated at a rammer working speed set greater than the engine idling speed;
• discriminating that the rammer has tipped over if the detected engine speed becomes equal to or smaller than the threshold value;
• and
• shutting down the engine when it is discriminated that the rammer has tipped over,
• wherein, when the detected engine speed becomes equal to or smaller than the threshold value and it is discriminated that the rammer has tipped over, the detected engine speed repeats a behavior of rising toward the rammer working speed and reversing to fall toward the threshold value again until the engine shutdown unit shuts down the engine.