JPH02305355A - Gas engine evaporator control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an evaporation control method for a gas engine that prevents the engine from stopping by controlling the flow rate of engine cooling water flowing into the evaporator.

(Prior Art) Conventional gas engines that use liquid fuel such as methanol are equipped with an evaporator that gasifies the liquid fuel.

The evaporator is equipped with a heater inside.

When the temperature of the engine cooling water is low, such as when starting the engine, the heater is energized to vaporize the liquid fuel.

When the warm-up of the engine is completed and the temperature of the cooling water reaches the set value 13 or higher, the engine cooling water is supplied to the evaporator, and the liquid fuel is vaporized by the engine cooling water, and then supplied to the heater. Power is cut off.

(Problem to be Solved by the Invention) In the conventional gas engine described above, when the temperature of the engine cooling water exceeds a set value T, the solenoid valve switches and the water flow control valve directs the engine cooling water with the adjusted flow rate to the evaporator. However, when switching from vaporization by the heater to vaporization by engine cooling water, if the opening speed of the water flow control valve is slow, water may accumulate in the pipe from the branch part that branches the solenoid valve and the water flow control valve to the solenoid valve. Cooling water with a low temperature may flow into the evaporator, causing the temperature inside the evaporator to drop temporarily, resulting in the engine stopping.

This invention was made for the purpose of improving the above-mentioned problems by controlling a water flow control valve.

It is an object of the present invention to provide a method for controlling an evaporator of a gas engine by preventing the engine from stopping when switching from a heater to engine cooling water.

(Means and operations for solving the problem) In order to achieve the above object, the present invention vaporizes liquid fuel using an electric heater provided in the evaporator and uses it as a starting fuel, and after warming up the engine, cools the engine. 1 when the temperature exceeds the set value.
A gas engine in which liquid fuel is vaporized by supplying engine cooling water to the evaporator.

When the temperature of the engine cooling water exceeds the set value, the water flow control valve that controls the flow rate of the engine cooling water flowing into the evaporator is fully opened for a preset time to allow a large amount of engine cooling water to flow into the evaporator.

After the set time has elapsed, the water flow control valve is PID-controlled to control the flow rate of engine cooling water flowing into the evaporator.

To provide a gas engine evaporator control method that prevents the gas engine from stopping by heating the inside of the evaporator with a large amount of engine cooling water when the vaporization of liquid fuel is switched from an electric heater to engine cooling water. It is.

(Example) An embodiment of the present invention will be described in detail with reference to the drawings.

In the figure, reference numeral 1 denotes a gas engine that vaporizes liquid fuel such as methanol and uses it as fuel. The liquid fuel contained in a tank 2 is sent to an evaporator 4 by a fuel pump 3.

The evaporator 4 is provided with an electric heater 5 and a heat exchanger 6 through which engine cooling water flows, and the liquid fuel is vaporized by the heat of either one, and the vaporized fuel is turned on and off. Valve 7. The pipe gas is sent to the mixer 9 via the gas pressure control valve 8, mixed with air in the mixer 9, and then supplied to the gas engine 1. After combustion, the pipe gas is discharged to the exhaust pipe 10. Ru.

In the figure, 12 is a radiator that radiates heat from engine cooling water.
The engine cooling water radiated by the radiator 12 is supplied to the gas engine I to cool the gas engine 1, and the cooling water that has cooled the gas engine 1 is branched into two routes from the middle of the pipe 13. , one side is the water flow control valve 14
One of the water flows into the radiator 12, and the other flows into the water flow control valve 14 via the electromagnetic valve 15, the heat exchanger 6 in the evaporator 4, and the water flow control valve 14.

Also, on the upstream side of the branch point 13a of the pipe line 13.

A temperature detector 17 is provided to detect when the engine cooling water reaches a set value T1, and the temperature signal detected by the temperature detector 17 is input to the controller 16.
6, the flow rate control valve 14 and the solenoid valve 15 are controlled as follows.

Next, the control method will be explained. FIG. 2 shows a flowchart during operation of the gas engine 1. When the gas engine 1 starts operating, the process proceeds from step ① to step ② except when the gas engine 1 is stopped, and the engine temperature detected by the temperature detector 17 is Cooling water temperature is set value TI (e.g. 80℃
) or less, and if it is less than the set value T1, step ■
The solenoid valve I5 is closed, and at the same time, the electric heater 5 and water pump (not shown) are turned on.

As a result, the fuel vaporized by the electric heater 5 is supplied from the evaporator 4 to the gas engine 1 via the mixer 9, and the gas engine 1 enters the operating state, and the flow advances to step (2) where the controller 16 controls the water amount. The opening degree of the valve 14 is set to 0%.

Thereafter, when the temperature of the engine cooling water rises due to operation of the gas engine 1 and exceeds the set value T1.

Proceed to step ``■'', open the solenoid valve 15, and turn off the electric heater 5 and water pump.

Thereafter, in the conventional method, the process proceeds to step ■'', where the controller 16 controls the opening and closing of the water flow control valve 14 by PTD control, and the solenoid valve 15
The flow rate of engine cooling water flowing into the heat exchanger 6 in the evaporator 4 was adjusted by starting the timer in the controller 16.

Then, the process proceeds to step ■', where it is determined whether the time set by the timer, for example, 30 seconds, has elapsed. If not, the process proceeds to step ■, where the controller 16 sets the opening degree of the water flow control valve 14 to 100%. do.

As a result, a large amount of engine cooling water whose temperature has exceeded the set temperature T1 flows into the heat exchanger 6 in the evaporator 4 by the solenoid valve 15, so even if the electric heater 5 is turned off, the evaporator 4
The temperature inside the gas engine 1 does not drop, thereby making it possible to prevent the gas engine 1 from stopping inadvertently.

Then, when the timer measures the set time, for example 30 seconds, and amplifies the timer, proceed to step ■''.

Thereafter, the water flow control valve 14 is PID-controlled by the controller 16, so that the engine cooling water with the amount of heat necessary for vaporizing the liquid fuel is supplied to the evaporator 4.

Note that the time set by the timer, 30 seconds, is the time for the evaporation pressure of the evaporator 4 to rise sufficiently.

The time is not limited to this time because it changes depending on the capacity of the evaporator 4 and the like.

(Effects of the Invention) As described in detail above, the present invention provides a system in which when the engine cooling water temperature exceeds a set value after warm-up of a gas engine,
This is because the water flow control valve is fully opened for a preset period of time, allowing a large amount of engine cooling water to flow into the heat exchanger in the evaporator.

Even if the heating inside the evaporator is switched from an electric heater to engine cooling water, the temperature inside the evaporator does not drop temporarily.

This reliably prevents the gas engine from being stopped inadvertently, and is economical because it can be implemented simply by providing a timer in the controller.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, with FIG. 1 being a circuit diagram and FIG. 2 being a flow chart showing the operation. 4... Evaporator, 5... Electric heater. 14...Water flow control valve.

Claims (1)

[Claims] The liquid fuel is vaporized by an electric heater 5 installed in the evaporator 4 to be used as fuel for starting, and when the temperature of the engine cooling water exceeds a set value after warm-up, the engine cooling water is supplied to the evaporator 4. In a gas engine that vaporizes liquid fuel using a gas engine, a water flow control valve 14 is set in advance to control the flow rate of engine cooling water flowing into the evaporator 4 when the temperature of the engine cooling water exceeds a set value. The feature is that the engine cooling water is fully opened for a period of time to allow a large amount of engine cooling water to flow into the evaporator 4, and after a set time has elapsed, the flow rate of the engine cooling water flowing into the evaporator 4 is controlled by PID controlling the water flow control valve 14. A method for controlling the evaporator of a gas engine.