Methanol engine, injection device and injection control method

The invention belongs to the field of machining, and discloses a methanol engine with stable methanol injection amount, an injection device and an injection control method. Comprising cylinders, air inlets of the cylinders are provided with air inlet pipes, air outlets of the cylinders are provided with exhaust pipes, and at least two methanol ejectors are arranged in each cylinder; the air cylinder is provided with a gear transmission structure, the gear transmission structure is provided with a displacement sensor, and the displacement sensor is used for obtaining displacement change parameters of the gear transmission structure and transmitting parameter data to an external control system to control parameters influencing injection of the methanol injector. Starting and closing of all the ejectors can be controlled in a self-adaptive mode according to the rotating speed of an engine and the load operation state, the ejection amount of the ejectors in work is adjusted, and therefore the influence of the met