Engine control device and cogeneration apparatus employing the engine control device

A cogeneration apparatus including an engine control device for controlling starting of an engine, comprising:

• a needle valve assembly including a step motor having a motor shaft for undergoing a rotational movement, a plunger for undergoing a linear vertical movement converted from the rotational movement of the motor shaft, and a needle valve body, the needle valve body having a needle disposed on the plunger, and an orifice, the needle and the orifice defining an opening therebetween, the opening having an opening degree variable to one of a first opening degree provided by the opening being opened by 50% and a second opening degree provided by the opening being opened by 70%, the needle being operable in response to the linear vertical movement of the plunger to vary the opening degree for adjusting a flow rate of gas to mix with an air into a fuel-air mixture to be supplied to the engine;
• a control section connected to the needle valve assembly for controlling the needle valve assembly to set the opening degree of the opening, the control section being configured to start, upon detection of a first operation signal, a predetermined number of times or less of cranking with the opening degree of the needle valve assembly set by the control section to the first opening degree in accordance with the first operation signal, and start, if a number of rotations of the engine has not yet reached a predetermined value through the cranking with the opening degree set to the first opening degree, the predetermined number of times or less of cranking with the opening degree of the needle valve assembly set by the control section to the second opening degree,
• wherein the plurality of opening degrees further includes a third opening degree larger than the second opening degree, and the control section is configured to start the predetermined number of times or less of cranking with the opening degree of the needle valve assembly set by the control section to the third opening degree if after varying the opening degree from the second opening degree back to the first opening degree the number of rotations of the engine has not yet reached the predetermined value through the cranking with the opening degree set to the first opening degree;
• and
• a shut-off valve connected to the needle valve assembly and the control section to be controlled by the control section to open for a predetermined period of time to allow supply of gas from a fuel supply source to the needle valve assembly during the predetermined number of times or less of cranking.

A method for controlling starting of an engine, comprising:

• providing a flow rate control valve having an opening degree variable to adjust a flow rate of gas to mix with an air into a fuel-air mixture to be supplied to the engine, and a storage section storing one mode of:
• a first mode in which the opening degree of the flow rate control valve is set to a first opening degree;
• a second mode in which the opening degree of the flow rate control valve is set to a second opening degree larger than the first opening degree;
• and
• a third mode in which the opening degree of the flow rate control valve is set to a third opening degree larger than the second opening degree;
• electronically retrieving the one mode stored in the storage section;
• determining whether the one mode stored in the storage section is the first mode;
• if the one mode stored in the storage section is the first mode, performing:
• attempting to start the engine in the first mode;
• determining whether a number of rotations of the engine has reached a number of idling rotations in the first mode;
• if the number of rotations of the engine has not reached the number of idling rotations in the first mode, varying the opening degree from the first opening degree to the second opening degree to attempt to start the engine in the second mode;
• determining whether the number of rotations of the engine has reached the number of idling rotations in the second mode after varying the opening degree from the first opening degree to the second opening degree to attempt to start the engine in the second mode;
• if the number of rotations of the engine has reached the number of idling rotations in the second mode after varying the opening degree from the first opening degree to the second opening degree to attempt to start the engine in the second mode, storing the second mode in the storage section;
• if the number of rotations of the engine has not reached the number of idling rotations in the second mode after varying the opening degree from the first opening degree to the second opening degree to attempt to start the engine in the second mode, varying the opening degree from the second opening degree to the third opening degree to attempt to start the engine in the third mode;
• determining whether the number of rotations of the engine has reached the number of idling rotations in the third mode after varying the opening degree from the second opening degree to the third opening degree to attempt to start the engine in the third mode;
• if the number of rotations of the engine has reached the number of idling rotations in the third mode after varying the opening degree from the second opening degree to the third opening degree to attempt to start the engine in the third mode, storing the third mode in the storage section;
• if the number of rotations of the engine has not reached the number of idling rotations in the third mode after varying the opening degree from the second opening degree to the third opening degree to attempt to start the engine in the third mode, informing a failure to start the engine;
• if the one mode stored in the storage section is not the first mode, determining whether the one mode stored in the storage section is the second mode;
• if the one mode stored in the storage section is the second mode, performing:
• attempting to start the engine in the second mode;
• determining whether the number of rotations of the engine has reached the number of idling rotations in the second mode;
• if the number of rotations of the engine has reached the number of idling rotations in the second mode, storing the second mode in the storage section;
• if the number of rotations of the engine has not reached the number of idling rotations in the second mode, varying the opening degree from the second opening degree to the first opening degree to attempt to start the engine in the first mode;
• determining whether the number of rotations of the engine has reached the number of idling rotations in the first mode after varying the opening degree from the second opening degree to the first opening degree to attempt to start the engine in the first mode;
• if the number of rotations of the engine has reached the number of idling rotations in the first mode after varying the opening degree from the second opening degree to the first opening degree to attempt to start the engine in the first mode, storing the first mode in the storage section;
• if the number of rotations of the engine has not reached the number of idling rotations in the first mode after varying the opening degree from the second opening degree to the first opening degree to attempt to start the engine in the first mode, varying the opening degree from the first opening degree to the third opening degree to attempt to start the engine in the third mode;
• determining whether the number of rotations of the engine has reached the number of idling rotations in the third mode after varying the opening degree from the first opening degree to the third opening degree to attempt to start the engine in the third mode;
• if the number of rotations of the engine has reached the number of idling rotations in the third mode after varying the opening degree from the first opening degree to the third opening degree to attempt to start the engine in the third mode, storing the third mode in the storage section;
• and
• if the number of rotations of the engine has not reached the number of idling rotations in the third mode after varying the opening degree from the first opening degree to the third opening degree to attempt to start the engine in the third mode, informing a failure to start the engine.