Engine control device
An engine control device includes: a compression release cylinder selecting part that selects, from a plurality of cylinders, one or more compression release cylinders to which fuel is not to be injected, depending on the magnitude of a required torque of an engine having the plurality of cylinders connected to an exhaust pipe provided with a catalyst for purifying exhaust gas; an exhaust valve control part that opens the exhaust valve of the compression release cylinder; a fuel injection amount determining part that determines the amount of fuel to be injected into an operating cylinder that differs from the compression release cylinder among the plurality of cylinders, according to a load torque generated by opening the exhaust valve and the required torque; and an injection control part that causes fuel, according to the determined amount of fuel injection, to be injected into the operating cylinder.
1. An engine control device comprising:
a required torque acquiring part that acquires a required torque for an engine having a plurality of cylinders connected to an exhaust pipe which is provided with a catalyst for purifying exhaust gas when a temperature of the catalyst reaches an activation temperature;
a compression release cylinder selecting part that selects, from the plurality of cylinders, one or more compression release cylinders for opening an exhaust valve without causing fuel to be injected during a compression process, depending on magnitude of the required torque;
an exhaust valve control part that opens an exhaust valve of the compression release cylinder during a compression process of the compression release cylinder;
a fuel injection amount determining part that determines an amount of fuel to be injected into an operating cylinder, which is a cylinder other than the compression release cylinder among the plurality of cylinders, where fuel is caused to be injected, according to a load torque generated by opening the exhaust valve and the required torque; and
an injection control part that controls a fuel injector that injects fuel into each cylinder to inject fuel, according to the amount of fuel injection determined by the fuel injection amount determining part, into the operating cylinder,
wherein the compression release cylinder selecting part selects the one or more compression release cylinders so that a sum of a power generation torque required for a generator, connected to the engine, to generate electric power and the load torque becomes a residual torque obtained by subtracting the required torque from the maximum output torque that can be output by the engine, and a ratio of the power generation torque to the remaining torque becomes large.
2. The engine control device according to claim 1 , wherein
the compression release cylinder selecting part increases the number of the compression release cylinders to be selected as the required torque is smaller.
3. The engine control device according to claim 1 , wherein
the compression release cylinder selecting part selects the one or more compression release cylinders so that a sum of an absolute value of the load torque generated by opening the exhaust valves of the one or more compression release cylinders and the required torque becomes equal to or less than a maximum output torque that can be output by the operating cylinder of the engine.
4. The engine control device according to claim 1 , wherein
the engine has four or more cylinders,
the compression release cylinder selecting part selects one compression release cylinder if the required torque is equal to or greater than a first threshold that is smaller than the maximum output torque of the engine,
the compression release cylinder selecting part selects three compression release cylinders if the required torque is equal to or less than a second threshold that is smaller than the first threshold, and
the compression release cylinder selecting part selects two compression release cylinders if the required torque is equal to or greater than the second threshold and less than the first threshold.
5. The engine control device according to claim 1 , wherein
the compression release cylinder selecting part selects the one or more compression release cylinders from the plurality of cylinders so that durations of compression release for each cylinder serving as the compression release cylinder becomes equal.
6. The engine control device according to claim 1 , wherein
the fuel injection amount determining part determines the amount of fuel injection such that an output torque of the engine at a time when fuel in the amount of fuel injection was injected into the operating cylinder becomes a sum of the load torque and the required torque.
7. The engine control device according to claim 1 , wherein
the compression release cylinder selecting part does not select the one or more compression release cylinders if a maximum power generation torque required for the generator to generate electric power at a maximum amount of power generation is equal to or greater than the residual torque, and
the compression release cylinder selecting part selects the one or more compression release cylinders if the maximum power generation torque is less than the residual torque.
8. The engine control device according to claim 7 , wherein
the compression release cylinder selecting part selects one compression release cylinder if a value obtained by subtracting the load torque by the one compression release cylinder from the residual torque is equal to or less than the maximum power generation torque, and
the compression release cylinder selecting part selects two or more compression release cylinders if a value obtained by subtracting the load torque by the one compression release cylinder from the residual torque is larger than the maximum power generation torque.