JPS5872667A - Control device for alcohol-reforming gas engine - Google Patents

Abstract

PURPOSE:To avoid the lowering of drivability by controlling the supply amount of alcohol on the basis of the temperature of a reformer and the supply pressure of reformed gas for preventing the pulsation caused by sudden acceleration or deceleration of an engine in an alcohol supply pipe. CONSTITUTION:A solenoid valve 4 controls the supply of alcohol, and an exhaust gas bypass valve 23 controls the flow of the exhaust gas to be supplied to a reformer. A controller 6 to control an air valve 21, a gas valve 22, and an alcohol injector 5 is supplied with signals from a temperature sensor 3, an operational amount sensor 7, an air-flow meter 8, a gas-pressure sensor 9, and a rotational speed sensor 10. When the temperature of the reformer is low, the solenoid valve 4 is closed to stop the supply of alcohol. When the temperature is higher than a set value, it is opened and closed in a fixed cycle in response to the output from a pulse width modulator 31.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a control device for an alcohol reformed gas engine, and particularly to an improvement in a device for controlling the supply of alcohol.

As a conventional alcohol reformed gas engine, there is one described, for example, in Japanese Patent Application Laid-Open No. 113426/1983.

This is configured as shown in Fig. 1, and the alcohol supplied to the reformer 1 equipped with a reforming catalyst is supplied from a constant pressure pump 2 to a constant pressure pump 2. Alcohol is supplied only when the discharge pressure is lower than the set discharge pressure, and the internal pressure of the reformer 1 is maintained at a substantially constant value.

Further, when the temperature of the reformer 1 is lower than the set value, the solenoid valve 4 is closed by a signal from the temperature sensor 3 to interrupt the supply of alcohol. That is, when the temperature of the catalyst installed in the reformer 1 is low and the activity is insufficient, such as when starting the engine or during initial warm-up operation, the alcohol reforming ability of the reformer 1 is low, so the reformer The alcohol supply to the engine 1 is stopped, and the engine is operated by separately injecting liquid alcohol from the injector 5. When the temperature of the reformer 1 rises above the set value due to the exhaust heat of the engine and becomes equipped with sufficient reforming capacity,
Solenoid valve 4 opens and alcohol is supplied.

, 7f is started.

The controller 6 includes an operation amount sensor 7 that detects the operation of an accelerator pedal or the like as an engine operating state parameter, an air flow meter 8 that detects the intake air flow rate of the engine, and an air flow meter 8 that detects the supply pressure of reformed gas. Output signals from the gas pressure S to be detected, the rotational speed sensor 10 to detect the engine rotational speed, and the temperature sensor 3 are respectively supplied. As shown in FIG. 2, the controller 6 includes a load calculation unit 11 that calculates the engine load, and a gas/fuel ratio calculation unit 12 that calculates the ratio of the current gas amount to the total fuel. Limit gas/fuel ratio calculation unit 13, gas/fuel ratio setting unit 14, fuel calculation unit 15, gas flow rate calculation unit 16, alcohol flow rate calculation unit 17, and reformed gas supply pressure Pg determined based on the reformed gas supply pressure. Close the accelerator [
Air pulp calculation unit 18 that calculates the air amount from s.
First and second comparators 19 and 20 are respectively provided for converging the reaction temperature of the reformer 1 within a predetermined range.
Then, the air flow rate, reformed gas flow rate, and alcohol flow rate are calculated according to the output information of each sensor, and the valve 21. Gas pulp 22 and injector 5 are controlled.

Further, the controller 6 controls the temperature of the reformer 1 to a set value,
For example, the solenoid valve °4 is kept closed until the temperature reaches 280°C, stopping the supply of alcohol to the reformer 1, and furthermore, when the temperature of the reformer 1 reaches another predetermined value, For example, when the temperature reaches 400°C or higher, the second comparator 20
With this output, the exhaust bypass 9P23 is opened to suppress an excessive rise in the temperature of the reformer 1, and the reaction temperature of the reformer 1 is kept stable. FIG. 3 is a controller 6 showing the operation of each control element as described above.
FIG.

Therefore, in the conventional system, the solenoid valve 4 for controlling the start and stop of the supply of alcohol for reforming was only operated in the 0N-OFF state depending on the temperature of the reformer 1, so after the engine was started, When the temperature of the reformer 1 rises and the solenoid valve 4 opens, alcohol begins to be supplied to the reformer 1 and the pressure inside the reformer 1 increases as reforming begins. and,
Since the amount of alcohol supplied is controlled by the balance between the discharge pressure of the constant pressure pump 2 and the internal pressure of the reformer 1, after the solenoid valve 4 is opened and the supply of reforming alcohol is started, for example, during
When the engine is stopped, the temperature of the reformer 1 drops again and the supply of alcohol is temporarily stopped. Especially during sudden acceleration immediately after starting the engine, a large amount of alcohol is supplied at once because the gas supply pressure is low. It will be done. Then, the temperature of the reformer 1 temporarily decreases, worsening the reforming reaction, and at the same time, the pressure rises excessively due to the evaporation of the excess supplied alcohol, resulting in intense pressure pulsations within the alcohol supply piping. At the same time, there is a possibility that engine drivability may deteriorate. This tendency is more pronounced as the thermal gate of the reformer becomes smaller. This pressure pulsation within the alcohol piping also occurs when the engine suddenly decelerates, leading to deterioration in knee/engine drivability.

In Fig. 1, 24 is a gas cooler, 25 is a check valve that only prevents the backflow of alcohol from the reformer 1 to the constant pressure pump 2, 26 is an air cleaner, 21 is a muffler, and 28 to 30 are servo pulps. .

The present invention has been made in view of the above, and by controlling the amount of alcohol supplied based on the temperature of the reformer and the supply pressure of reformed gas, the present invention is capable of controlling the amount of alcohol supplied based on the temperature of the reformer and the supply pressure of reformed gas. To prevent excessive supply of alcohol by supplying alcohol, and thereby prevent pulsation in the alcohol supply pipe that occurs due to sudden acceleration or deceleration of the engine, thereby avoiding deterioration in drivability such as engine breathing and sluggishness. With the goal.

The present invention will be explained in detail below based on an embodiment shown in FIG. In the drawings, parts having the same functions as those in the prior art are designated by the same reference numerals, and detailed explanation thereof will be omitted.

A solenoid valve 4 that controls the supply of alcohol, an exhaust bypass valve 23 that controls the exhaust llL violet supplied to the reformer, and
The controller 6 that controls the air valve 21, the gas valve 22, and the alcohol injector 5 includes a temperature controller 3.
, the reformer temperature, from the manipulated variable sensor 1, air flow meter 8, gas pressure sensor 9 and rotation speed sensor 10,
It supplies signals for accelerator operation amount, intake air amount, gas supply pressure, and engine rotation speed.

Here, the exhaust bypass valve 23Fi is connected to the second exhaust bypass valve 23Fi as in the conventional case.
The opening/closing of the solenoid valve 4 is controlled according to the output of the comparator 20, and the solenoid valve 4 is supplied with a set value for detecting the completion of warm-up of the reformer 1 and the output of the temperature sensor 3 in the same manner as in the past. A pulse width modulator (PWM) 3 converts the output of the first comparator 19 and the output of the gas pressure sensor 9 into pulse widths.
The output of 1- and 〆C are supplied through an AND gate 32.

The pulse width modulator 31 is set to lengthen the on-time ratio of the reference pulse, which is turned on and off at a predetermined period, as the gas supply pressure increases, and the first comparator 19 is set so that the output is turned on when the temperature of the reformer 1 becomes higher than a set value, for example 280°C.

Therefore, when the temperature of the reformer 1 is low, the solenoid valve 4
The valve is kept closed and alcohol supply M1 is stopped, but when the temperature of the reformer 1 rises higher than the set value, it opens and closes at a predetermined and constant cycle in response to the output of the valve modulator 31. Furthermore, since the time ratio of the ON pulse output from the Hals modulator 31 increases as the gas supply pressure increases, the time ratio of the solenoid valve 4 being open increases as the gas supply pressure increases. .

That is, in principle, when the pressure of the reformed gas is close to the discharge pressure of the constant pressure pump 2, alcohol is supplied from the pump 2 to the reformer 1 by the amount of pressure reduced due to gas consumption. However, when the consumption of reformed gas is rapid and large (during sudden engine acceleration), the lower the pressure of the gas, the smaller the pulse width modulator 31 outputs a pulse with a smaller on-time ratio. Since alcohol is supplied in response to this, the amount of alcohol supplied decreases.

Therefore, there is no risk of excessive alcohol being supplied even when the reformer is warmed up immediately after startup, that is, when alcohol supply is started, due to acceleration, etc., and the amount of alcohol that corresponds to the actual reforming capacity is supplied. Therefore, it is possible to prevent pulsation in the Alco gas supply piping, and there is no possibility that insufficiently reformed gas will be supplied to the engine.

Further, when the supply pressure of the reformed gas and the temperature of the reformer both reach a predetermined value or higher, the on-time ratio of the output pulse of the pulse width modulator 31 becomes 100X, and the solenoid valve 4 is kept fully open. Therefore, the supply/stop of alcohol is controlled by the balance between the discharge pressure of the constant pressure pump 2 and the reformed gas pressure, and new reformed gas corresponding to the consumed gas cap is generated.

Note that the control sections for the air valve 21, gas pulp 22, and alcohol injector 5 are the same as those in the prior art, so their explanation will be omitted.

As explained above, according to the present invention, the amount of alcohol supplied for reforming is controlled based on the temperature of the reformer and the supply pressure of reformed gas. Since there is no risk of excessive alcohol being supplied to the reformer, it is possible to avoid the engine malfunction that was seen when switching to operation using reformed gas.

Figure 1 is a system diagram of a conventional example, Figure 2 is a block diagram of the controller in Figure 1, Figure 3 is a sequence diagram of the same as above, and Figure 4 shows an embodiment of the present invention. It is a block diagram of a controller.

1... Reformer 2... Constant pressure pump 3... W
e-sensor 4...Solenoid valve 6...Controller 9...Gas pressure sensor 19...Comparator
31...Pulse width modulator 32...AND gate patent Applicant: Fujio Sasashima, patent attorney representing Nissan Motor Co., Ltd.

Claims (1)

[Claims] In an alcohol reformed gas engine configured to supply reformed gas fuel obtained by thermally decomposing alcohol and unreformed liquid fuel, a temperature sensor detects the temperature of a reformer for reforming alcohol; , a solenoid valve that controls the amount of alcohol supplied to the reformer, a gas pressure sensor that detects the supply pressure of reformed gas, and a solenoid valve that closes when the reformer temperature is lower than the set value to perform reforming. A controller that opens the solenoid valve when the temperature of the chamber is higher than a set value and outputs a control signal to the solenoid valve so as to lengthen the opening time of the solenoid valve as the supply pressure of reformed gas increases. , a control device for an alcohol reformed gas engine.