WO2016084368A1

WO2016084368A1 - Rotation control system for bi-fuel engine

Info

Publication number: WO2016084368A1
Application number: PCT/JP2015/005845
Authority: WO
Inventors: 智津坂
Original assignee: 株式会社ニッキ
Priority date: 2014-11-25
Filing date: 2015-11-24
Publication date: 2016-06-02
Also published as: JP2018013039A

Abstract

The purpose of the present invention is to prevent a drop in engine rotation speed and loss of stable engine rotation in a bi-fuel engine when the fuel that the bi-fuel engine is running on is switched. A relay (81) that is switched by a changeover signal from a fuel switching device (7) and an electrical resistance (82) are series connected in an input circuit (8) that inputs water temperature data for engine cooling water detected by a water temperature sensor (104) to an electronic control unit (ECU) (5). When the fuel to be used is switched, the relay (81) is operated so that the electric resistance (82) is added to the water temperature data from the water temperature sensor (104) to produce a value that increases the target rotation speed such that the rotation speed is controlled to a stable rotation speed.

Description

Bifuel engine rotation control device

The present invention relates to a rotation control device that controls the rotational speed of a bi-fuel engine that switches between and uses different types of fuel such as liquid fuel such as gasoline and compressed natural gas (CNG).

Conventionally, a bi-fuel engine has been able to operate using a different fuel such as liquid fuel and gaseous fuel such as gasoline and compressed natural gas (CNG) or gasoline and liquefied petroleum gas (LPG) for one engine, for example. Are known.

And since the vehicle using this bi-fuel engine can draw out the optimum condition of the fuel used according to the change of the traveling environment, it is extremely economical and can select the fuel according to the situation. It is considered to be environmentally friendly and has been introduced worldwide.

By the way, when the bifuel engine is operated by switching to a gaseous fuel such as compressed natural gas (CNG) in an operating condition of an engine using a liquid fuel such as gasoline, the liquid fuel before switching is used Compared to the engine, the combustibility of gaseous fuel is reduced due to the relationship with the compression ratio of the engine, and the stability of rotation is impaired particularly when the engine speed is reduced as during idle operation Problem of being

In order to solve such a problem, the determination means for determining the use time of the gaseous fuel or the liquid fuel, and at least the solenoid valve provided in the bypass passage is opened to increase the intake amount, and the liquid fuel is used. JP-A-62-96742 (Patent Document 1) discloses a means for obtaining good combustibility even at the time of use of gaseous fuel at low rotation such as idle operation by increasing the intake amount as compared with the time of use. Is presented on.

However, when switching from liquid fuel to gaseous fuel, the invention described in Patent Document 1 opens the solenoid valve to increase the intake amount, so a bypass passage etc. is required, and a new design is required. It is still difficult to implement the system, for example, in the case of converting it to a bi-fuel engine based on a gasoline engine for the purpose of providing it at a low price.

In addition, as a means that can perform idling stably even if the fuel is switched without major modification, the electronic control unit (ECU) controls the amount of intake during idle operation provided in the intake passage of the by fuel engine by the electronic control unit (ECU) The means for adjusting the amount of intake air is controlled by controlling the electronic throttle device based on the control value for correcting the amount of intake air calculated according to the fuel switched to control the idle rotational speed to the target idle rotational speed. Although disclosed in Japanese Patent Application Laid-Open No. 2011-214543 (Patent Document 2), it is necessary to create a program in accordance with the fuel to be used, and there is a problem that time and labor are required and control becomes complicated.

Japanese Patent Application Laid-Open No. 62-96742 JP, 2011-214543, A

The present invention has been made to solve the problems of the conventional bifuel engine idle rotation control system, and it is a complicated program that does not require major modifications such as expansion of the intake passage. It is an object of the present invention to provide a device capable of performing idle rotation control of a bifuel engine with few inexpensive parts without control by the above.

The present invention, which has been made to solve the above problems, includes water temperature data of engine cooling water whose rotational speed is detected by a water temperature sensor in a bifuel engine in which two types of fuel having different properties are switched and used by a fuel switching device. A rotation control device of a bi-fuel engine that controls a target rotation speed calculated by an electronic control device using data detected from various detection devices in an engine, and is connected between the water temperature sensor and the electronic control device Connected to one of the relays having two output terminals switched by the switching signal from the fuel switching device to an input circuit for inputting the coolant temperature data of the engine coolant detected by the coolant temperature sensor to the electronic control unit Electrical resistances of the specified value are connected in series, The relay operates when the fuel is switched, and the water temperature data from the water temperature sensor is output to the electronic control device as a value to which the electric resistance is added or a value obtained by subtracting the electric resistance, and the target rotational speed is increased. Alternatively, it is characterized in that it is lowered and controlled to a stable rotational speed.

Further, in the present invention, when the fuel changes and the speed of the vehicle equipped with the bi-fuel engine falls below a predetermined speed or the injection time of the fuel injection valve falls below a predetermined injection time, the relay operates and the water temperature By controlling the water temperature data from the sensor to increase the target rotation speed as a value to which the electric resistance is added, control can be performed when the engine rotation speed is large due to the fuel used, and the normal operation can be performed. Sometimes, by not activating, it is possible to perform appropriate operation control and prevent wasteful consumption of fuel.

Furthermore, in the present invention, when the electric resistance is a variable resistance, not only the resistance value can be changed according to the characteristics of the fuel or engine used but also it is necessary to prepare many kinds of electric resistance in the manufacturing process. It is also convenient in terms of parts management.

According to the present invention, the problem of the bi-fuel engine can be reliably achieved with a small amount of inexpensive parts and a simple control circuit, without requiring extensive modification such as expanding the intake passage, and without controlling by a complicated program. It is possible to perform rotation control that eliminates instability in the low rotation range that occurs due to the nature of a certain fuel.

BRIEF DESCRIPTION OF THE DRAWINGS The whole schematic block diagram of the bi-fuel engine system in the preferable embodiment of this invention. FIG. 2 is a block circuit diagram showing the main parts in the overall schematic configuration diagram shown in FIG. 1; The chart which shows target idle revolving speed and engine revolving speed about a comparative example to which the present invention is not applied. FIG. 6 is a chart showing target idle rotation speed and engine rotation speed with respect to the movement of the relay in the embodiment shown in FIG. 1; The relationship figure of the temperature of a cooling water, and a target rotational speed. The chart which shows the characteristic of temperature and resistance value of the thermistor. The chart which shows the target revolving speed and engine revolving speed to the movement of the relay in a different embodiment. The chart which shows the target revolving speed and engine revolving speed to the movement of the relay in still another embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic view of a preferred embodiment of the present invention, and generally the two fuel tanks 1 and 2 consist of gasoline, for example liquid fuel, as in the previously known bifuel engine system. A first fuel 11 and a second fuel 21 consisting of CNG, which is a gaseous fuel, are respectively stored, and a selected one of these fuels is selected via the first fuel supply pipe 12 or the second fuel supply pipe 22. The fuel is injected from the dedicated first fuel injection valve 13 and the second fuel injection valve 23 installed in the intake passage 3 of the engine.

Then, for example, the intake pipe pressure detected by the intake pipe pressure sensor 101 provided in the intake passage 3, the engine rotational speed detected by the engine rotation detection sensor 102, the throttle opening detected by the throttle sensor 103, the coolant temperature sensor 104 The electronic control unit (ECU) 5 calculates a predetermined fuel injection amount using a predetermined program using the water temperature detected by the oxygen concentration and the oxygen concentration in the exhaust gas detected by the oxygen sensor 105 installed in the exhaust passage 4. The fuel injection control method is performed to perform the open / close control of the fuel injection valves 13 and 23, the ignition timing control of the spark plug 6, the rotation control including idle, etc. Fuel switching is automatic or manual fuel switching The first fuel 11 or gas which is liquid fuel (gasoline) stored in the fuel tanks 1 and 2 by the device 7 Is the same as the conventional ones using charge a second fuel 21 is (CNG) select.

In the present embodiment, even when any of the first fuel 11 and the second fuel 21 is used, the operation control is performed by one electronic control unit (ECU) 5, but the first fuel 11 and the second fuel 21 are used. The fuel 21 may be controlled by an individual electronic control unit (ECU) (not shown).

In particular, in the present embodiment, the electronic control unit (ECU) 5 is connected between the water temperature sensor 104 and the electronic control unit (ECU) 5 and detects the water temperature data of the engine coolant detected by the water temperature sensor 104. A relay 81 and an electrical resistor 82 are connected in series to an input circuit 8 to be input to the circuit.

More specifically, as shown in FIG. 2, the relay 81 connected to the input circuit 8 is connected to a water temperature sensor 104 of engine cooling water, and an input terminal for inputting a water temperature data signal from the water temperature sensor 104. 83 and two

output terminals

84a and 84b switched by a fuel switching signal from the fuel switching device 7. Further, an electric resistance 82 is connected in series to one of the

output terminals

84a and 84b. It is connected to the input terminal 51 of the electronic control unit (ECU) 5.

The relay 20 has at least one input terminal 83 and two

output terminals

84a and 84b, and can be switched to the

output terminal

84a or 84b by a fuel switching signal from the fuel switching device 7. For example, any type of electromagnetic relay using an electromagnet or an electronic relay using a thyristor or a triac may be used.

In the present embodiment having the above configuration, the intake pipe pressure, engine rotational speed, throttle opening degree, water temperature, oxygen in exhaust gas detected by each of the sensors, as in the control system of the conventionally known bifuel engine The fuel injection valve 13 or 23 is controlled to open or close based on the required fuel injection amount calculated by a predetermined operation program which is previously determined and recorded in an electronic control unit (ECU) 5 using detection data such as concentration. At the same time, the fuel injection control method including the air fuel ratio control such as the ignition timing control of the spark plug 6 and the engine rotation control is executed.

Next, engine rotation control according to the present embodiment will be described in detail.

The present embodiment is an implementation of the present invention for idle rotation control, and, for example, the start of the bifuel engine and the liquid fuel (gasoline) in which the idle operation immediately after start is stored in the fuel tank 1 The fuel supply to the engine is switched to the second fuel 21 which is a gaseous fuel (CNG) stored in the fuel tank 2 by the fuel 11 and thereafter by the automatic or manual fuel switching device 7.

In the present embodiment, as shown in FIG. 2, when the engine is started, it is used as a factor necessary for setting the amount of intake, the amount of fuel injection, etc. for controlling the operation of the engine. The detection data from the water temperature sensor 104 for detecting the temperature of the cooling water of the engine, which is one of the data, is input to the electronic control unit (ECU) 5 through the input circuit 8, but in the present embodiment And the idle operation immediately after the start is performed by the first fuel 11 which is the liquid fuel (gasoline) stored in the fuel tank 1. At this time, the relay 81 is connected to the output terminal 84a on the side where the electric resistance 82 is not connected. The water temperature data of the actual measurement value is input to the electronic control unit (ECU) 5 as it is short-circuited and processed by the operation program set in advance, and the intake amount, fuel It is operated by controlling the electronic throttle device 9 as such morphism amount becomes the target idle rotational speed is calculated.

Next, in the present embodiment, as described above, when the engine is started by the first fuel 11 which is liquid fuel (gasoline) and shifted to idle rotation, the fuel switching device 7 switches the operation to receive an instruction to that effect. The electronic control unit (ECU) 5 stops the supply of the first fuel 11 to the first fuel injection valve 13 which was injecting the first fuel 11 which is the liquid fuel (gasoline), and the other second fuel The second fuel 21 which is gaseous fuel (CNG) stored in the fuel tank 2 is supplied from the injection valve 23 and idle rotation is continued.

Here, in the present embodiment, a command based on a fuel switching command from the fuel switching device 7 is sent from the electronic control unit (ECU) 5 to the relay 81, and the relay 81 is activated to operate the electric resistance 82. A value obtained by adding the resistance value of the electric resistance 82 to the water temperature data of the measured value is input to the electronic control unit (ECU) 5 as the water temperature data and is used as the fuel. The electronic throttle device 9 is processed by the operation program set in advance as in the case of using the first fuel 11 which is liquid fuel (gasoline) to calculate the intake amount, the fuel injection amount, etc., and achieve the target idle rotation speed. Control and drive.

Therefore, in the present embodiment, after the engine is started using the first fuel 3 that is liquid fuel (gasoline) as the fuel and after switching from the idle operation state immediately after that to the second fuel 4 that is gaseous fuel (CNG) Since the water temperature data from the water temperature sensor 104 is recognized as data of the water temperature lower than the actual measurement value, the target idle rotation speed is increased by the resistance of the electric resistance 82, so the first fuel 11 which is liquid fuel (gasoline) Even if the fuel is switched to the second fuel 21 which is a gaseous fuel (CNG), stable idle rotation control can be performed without a decrease in engine rotation speed as in the prior art.

FIG. 3 is a chart showing target idle rotation speed and engine rotation speed for the conventional embodiment to which the present invention is not applied, and shows the first fuel which is liquid fuel (gasoline) to the second fuel which is gaseous fuel (CNG) When switching to the above, the engine rotational speed decreases, and when switching from the second fuel (CNG) to the first fuel (gasoline), the engine speed increases. In both cases, the stability of the rotational speed is impaired.

On the other hand, in the present embodiment, as is apparent from the chart showing the target idle rotation speed and the engine rotation speed shown in FIG. 4, the fuel supplied to the engine is the first fuel which is liquid fuel (gasoline) The relay is switched at the same time as switching to the second fuel which is gaseous fuel (CNG), and the resistance value of the electric resistance 21 is added to the water temperature data from the water temperature sensor 104 as described above to increase the target idle rotation speed. As in the prior art shown in 3, it has been demonstrated that stable rotation is maintained without a decrease in engine rotation speed.

FIG. 5 is a diagram showing the relationship between the temperature of the cooling water and the target idle rotation speed, and shows that the target idle rotation speed is in a relationship of increasing when the temperature of the cooling water decreases. Further, FIG. 6 shows the relationship between the resistance value of the thermistor usable as the electric resistance 82 and the temperature, and based on the relationship between the temperature of the cooling water and the target idle rotation speed shown in FIG. The resistance value necessary for lowering the coolant temperature data to that temperature is shown, for example, in FIG. 6 by determining the temperature of the apparent engine cooling water to be lowered by the reduction of the rotational speed when switching from 1 fuel 11 to the second fuel 21. The electric resistance 82 having the value may be set in advance, which is obtained from the relationship between the temperature and the resistance value.

In the present embodiment, when the fuel to be used is switched, the relay 81 is activated and the water temperature data from the water temperature sensor 104 is output to the electronic control unit (ECU) 5 as a value obtained by adding the resistance value of the electric resistance 82. In the case where the target rotational speed is increased and controlled to a stable rotational speed, the relay 81 is activated when the fuel to be used is switched, and the water temperature data from the water temperature sensor 104 indicates the resistance 82 It is also possible to output a value obtained by subtracting the value to the electronic control unit (ECU) 5 to lower the target rotational speed and control the rotational speed to be stable.

In the present embodiment, a fixed resistance having a predetermined resistance value is used in advance according to the type of fuel used as described above as the electric resistance 82. However, the electric resistance 82 is used as a variable resistance. It is extremely convenient because it can be set to a desired resistance value depending on the fuel to be used.

FIGS. 7 and 8 are charts showing the target rotation speed and the engine rotation speed for different embodiments of the present invention and further different embodiments, and the configuration of the system is the same as that of the embodiment shown in FIG. It can be implemented.

Then, in the embodiment shown in FIG. 4, when the fuel is switched from the first fuel 11 to the second fuel 21, the relay 81 is activated and the water temperature data from the water temperature sensor 104 adds the resistance value of the electric resistance 82. In the embodiment shown in FIG. 7, the bifuel engine is mounted when the fuel is switched from the first fuel 11 to the second fuel 21 in the embodiment shown in FIG. In the embodiment shown in FIG. 8 when the speed of the vehicle falls below the predetermined speed, when the fuel is switched from the first fuel 11 to the second fuel 21 and the injection time of the fuel injection valve falls below the predetermined injection time In this case, the relay 81 is operated to control the water temperature data from the water temperature sensor 104 to increase the target rotational speed as a value obtained by adding the electric resistance 82.

In these embodiments, stable rotation is obtained by performing engine rotation increase control when the engine rotation speed is low, which is likely to be affected by the nature of the second fuel 21 made of gaseous fuel (CNG) that is the used fuel. In addition to being able to switch to the second fuel 21 made of gaseous fuel (CNG), it has the advantage that appropriate operation control and wasteful consumption of fuel can be prevented by not operating during normal operation. .

DESCRIPTION OF SYMBOLS 1 fuel tank, 2 fuel tank, 3 intake passage, 4 exhaust passage, 5 electronic control unit (ECU), 6 spark plug, 7 fuel switching device, 8 input circuit, 9 electronic throttle device, 11 first fuel, 12 first Fuel supply pipe, 13 first fuel injection valve, 21 second fuel, 22 second fuel supply pipe, 23 second fuel injection valve, 51 input terminal, 81 relay, 82 electric resistance, 83 input terminal, 84a output terminal, 84b Output terminal, 101 intake pipe pressure sensor, 102 engine rotation detection sensor, 103 throttle sensor, 104 water temperature sensor, 105 oxygen sensor

Claims

In a bi-fuel engine in which two types of fuel having different properties are switched and used by a fuel switching device, data detected from various detection devices in the engine including water temperature data of engine cooling water whose rotation speed is detected by a water temperature sensor A rotation control device of a bifuel engine that controls to a target rotation speed calculated by an electronic control device, wherein water temperature data of engine cooling water which is connected between the water temperature sensor and the electronic control device and detected by the water temperature sensor A relay having two output terminals switched by the switching signal from the fuel switching device and an electric resistance of a predetermined value connected to one of the output terminals of the relay are connected in series to an input circuit for inputting And when the fuel to be used is switched, the relay The water temperature data from the water temperature sensor is output to the electronic control unit as a value to which the electrical resistance is added or as a value from which the electrical resistance is subtracted, and the target rotational speed is increased or decreased to control the stable rotational speed. A rotation control device for a bifuel engine characterized by:
When the fuel changes and the speed of the vehicle equipped with the bi-fuel engine falls below a predetermined speed, the relay operates to raise the target rotation speed as a value obtained by adding the electric resistance to the water temperature data from the water temperature sensor. The rotation control device for a bifuel engine according to claim 1, wherein the control is performed to
When the fuel changes and the injection time of the fuel injection valve falls below a predetermined injection time, the relay operates to control the water temperature data from the water temperature sensor to increase the target rotational speed as a value obtained by adding the electric resistance. The rotation control device for a bifuel engine according to claim 1, wherein:
The rotation control device for a bifuel engine according to claim 1, 2 or 3, wherein the electric resistance is a variable resistance.