JP5408027B2 - Gas composition detection system and engine control system - Google Patents

Description

  The present invention relates to a gas composition detection system and an engine control system.

  In an apparatus for burning gas fuel, a technique for discriminating the type of gas fuel supplied to the apparatus has been developed. For example, in Patent Document 1, in an apparatus in which either LP gas (LPG) or dimethyl ether (DME) is supplied as gas fuel, the temperature of the supplied gas fuel is higher than the condensation point of LPG and lower than the condensation point of DME. And a technique for determining whether the supplied gas fuel is LPG or DME based on the condensed state of the gas fuel at the time of cooling.

  There are engines that use compressed natural gas (CNG) as gas fuel. A CNG engine for automobiles has also been developed. For example, Patent Document 2 describes a CNG engine for automobiles that uses gasoline and CNG in combination.

Japanese Patent Laid-Open No. 2003-042981 JP 2005-113698 A Japanese Patent Laid-Open No. 06-249809

  CNG is a gas fuel containing methane as a main component, but components other than methane such as butane and propane are mixed, and the composition varies depending on the production area and refining time of CNG. Information on the exact composition of CNG is particularly important in the case of precise air-fuel ratio control in an automobile engine or the like, but the technique described in Patent Document 1 detects the composition of a mixed gas composed of a plurality of components. I can't do it.

  This invention is made | formed in view of this point, and it aims at providing the gas composition detection system which can detect the composition of the gas which consists of a some component. It is another object of the present invention to provide an engine control system capable of performing air-fuel ratio control of an engine for burning gas fuel based on the composition of the gas fuel.

  The present invention for solving the above problems is to cool a test gas having a constant volume composed of a plurality of components, detect a pressure drop caused by condensation of each component in the test gas in the cooling process, and A gas composition detection system that identifies the condensed components based on the temperature at which the decrease occurs, calculates the proportion of the condensed components in the test gas based on the pressure drop, and detects the composition of the test gas. is there.

Specifically, a gas composition detection system for detecting a composition of a test gas composed of a plurality of components,
A constant volume container;
A cooling device for cooling the test gas in the container;
Pressure detecting means for detecting the pressure of the test gas in the container;
Temperature detecting means for detecting the temperature of the test gas in the container;
A test gas is introduced into the container, the introduced test gas is cooled by the cooling device, and a pressure drop caused by condensation of each component in the test gas in the course of the cooling is detected by the pressure detection means; The temperature at which the pressure drop is detected is detected by the temperature detecting means, the condensed component is specified based on the detected temperature, and the condensed component of the test gas is determined based on the pressure drop amount. Gas composition detection processing means for calculating a ratio;
A gas composition detection system comprising:

  When a test gas composed of a plurality of components is introduced into the vessel and cooled, condensation of each component starts at the boiling point of each component. When a component in the test gas condenses, the pressure in the container rapidly decreases, so when a sudden pressure drop is detected by observing the pressure change in the cooling process, the component in the test gas is condensed. I can judge.

  The temperature at which this sudden pressure drop is detected corresponds to the boiling point of the condensed component. Therefore, the condensed component can be specified based on the temperature when the pressure drop occurs.

  The amount of pressure drop caused by the condensation of a component in the test gas, i.e., the difference between the pressure at the start of condensation and the pressure at the end of condensation, is the difference in the component in the test gas before it begins to condense. Corresponds to partial pressure.

  Therefore, based on the ratio of the pressure drop caused by the condensation of this component and the pressure of the test gas before this component begins to condense, the ratio of that component in the test gas before this component is condensed is calculated. can do. Based on this ratio, the ratio of each component in the test gas initially introduced into the container can be calculated.

  Thus, according to the gas composition detection system of the present invention, it is possible to detect the composition (component and ratio) of a gas composed of a plurality of components.

  Natural gas can be illustrated as gas which can detect a composition suitably by the gas composition detection system which concerns on this invention. When the composition of natural gas is detected by the gas composition detection system of the present invention, the test gas may be cooled to the boiling point of methane, which is the lowest boiling component among the main components of natural gas. .

The gas composition detection system of the present invention comprises:
An introduction passage for introducing a test gas into the container;
A discharge passage for discharging the test gas in the container;
An introduction passage opening and closing valve for opening and closing the introduction passage;
A discharge passage opening / closing valve for opening and closing the discharge passage;
With
The gas composition detection processing means includes valve control means for controlling the introduction passage opening / closing valve and the discharge passage opening / closing valve,
The valve control means includes
When introducing the test gas into the container, control to open the introduction passage on-off valve and close the discharge passage on-off valve,
When cooling the test gas by the cooling device, control to close the introduction passage on-off valve and close the discharge passage on-off valve,
When the detection of the composition of the test gas is completed, the introduction passage opening / closing valve and the discharge passage opening / closing valve are controlled to close the introduction passage opening / closing valve and open the discharge passage opening / closing valve. be able to.

As described above, since the composition of natural gas varies depending on the production area and purification time, in order to perform precise combustion control in an engine using natural gas as a fuel, information on the composition of natural gas used for combustion is required. Become. Therefore, the gas composition detection system according to the present invention can be suitably incorporated in an engine control system that burns gas fuel such as natural gas.

That is, a control system for an engine that burns gas fuel, including the above gas composition detection system,
Gas fuel composition detection means for detecting the composition of the gas fuel supplied to the fuel injection device of the engine by the gas composition detection system;
Combustion control means for performing combustion control of the engine based on the composition detected by the gas fuel composition detection means;
An engine control system comprising: is also included in the scope of the present invention.

  According to this engine control system, even in an engine that burns gas fuel whose composition varies depending on the production area and refining time such as natural gas, engine combustion control according to the gas fuel to be used for combustion can be performed. It becomes possible. Therefore, it is possible to precisely control the air-fuel ratio so that the engine performance, fuel consumption performance, exhaust performance, etc. of the gas fuel engine satisfy predetermined requirements.

  In an engine that burns gas fuel, such as natural gas, whose composition varies depending on the production area and purification time, if new gas fuel is filled in storage means such as a fuel tank that stores gas fuel, it has been used for combustion until then. There is a possibility that a gas fuel having a composition different from that of the gas fuel is subjected to combustion.

Therefore, in the above engine control system,
Gas fuel filling detection means for detecting that the gas fuel is filled in the storage means for storing the gas fuel,
The gas fuel composition detection means may detect the composition of the filled gas fuel when the gas fuel filling detection means detects that the storage means is filled with gas fuel.

  Thereby, when new gas fuel is filled, the composition is detected, and engine combustion control based on the detected composition is performed. Therefore, it is possible to perform optimal engine combustion control in accordance with the composition of the gas fuel newly filled in the storage means.

  In the engine control system, the gas fuel composition detection means detects the composition by the gas composition detection system using the gas fuel upstream of the regulator for adjusting the pressure of the gas fuel supplied to the fuel injection device as a test gas. May be performed.

  By using the high-pressure gas fuel before the pressure is adjusted by the regulator as the test gas, the energy required for cooling the test gas can be reduced. Therefore, the influence on the fuel consumption performance when the gas composition detection system according to the present invention is incorporated in an engine control system can be suppressed.

In the above engine control system,
The engine is a vehicle driving engine mounted on a vehicle,
A regenerative device for recovering the kinetic energy of the vehicle as regenerative energy;
The gas composition detection system may be configured to cool the test gas with the regenerative energy recovered by the regenerative device.

Thereby, the influence on the fuel consumption performance when the gas composition detection system according to the present invention is incorporated in an engine control system can be suppressed. Examples of the regenerative device include a configuration including an alternator that converts kinetic energy of a vehicle into electric energy, a battery that stores generated electricity, and the like.

  ADVANTAGE OF THE INVENTION According to this invention, the gas composition detection system which can detect the composition of the gas which consists of a some component can be provided. In addition, it is possible to provide an engine control system capable of performing air-fuel ratio control of an engine for burning gas fuel based on the composition of the gas fuel.

1 is a diagram illustrating a schematic configuration of a gas composition detection system according to Embodiment 1. FIG. It is the figure which showed the pressure change at the time of cooling methane, propane, and butane which are the main components of natural gas by a single component. It is the figure which illustrated the pressure change at the time of cooling in order to detect the composition of the natural gas which has methane as a main component and propane and butane are mixed a little by the gas composition detection system which concerns on Example 1. FIG. 3 is a flowchart illustrating a gas composition detection process executed by the gas composition detection system according to the first embodiment. It is a figure which shows schematic structure of the gas fuel engine system which concerns on Example 2. FIG. It is a figure which shows schematic structure of the gas fuel engine system which concerns on Example 2. FIG. 7 is a flowchart showing air-fuel ratio control based on a gas composition detection processing result executed in a gas fuel engine system according to Embodiment 2.

  Hereinafter, embodiments of the present invention will be described in detail. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

Example 1
FIG. 1 is a diagram showing a schematic configuration of a gas composition detection system according to the present embodiment. In FIG. 1, a gas composition detection system 39 is a system for detecting the composition of a test gas composed of a plurality of components, and includes a container 37 having a constant volume and an introduction passage 29 for introducing the test gas into the container 37. The inlet passage opening / closing valve 30 for opening and closing the introduction passage 29, the discharge passage 35 for discharging the test gas in the container 37, the discharge passage opening / closing valve 34 for opening and closing the discharge passage 35, and the test gas in the container 37 are cooled. A cooling device 31, a pressure sensor 33 (pressure detection means) for detecting the pressure of the test gas in the container 37, a temperature sensor 32 (temperature detection means) for detecting the temperature of the test gas in the container 37, and a controller 36 .

  The controller 36 is a computer having a CPU, a ROM, a RAM, and the like. The detection values from the pressure sensor 33 and the temperature sensor 32 are input to open / close the introduction passage opening / closing valve 30 and the discharge passage opening / closing valve 34 and to operate the cooling device 31. Configured to control.

  The controller 36 controls the opening and closing of the introduction passage opening / closing valve 30 and the discharge passage opening / closing valve 34 to introduce and seal the test gas into the container 37, and to control the cooling device 31 to cool the test gas. Based on the pressure detected by the sensor 33 and the temperature detected by the temperature sensor 32, a process for detecting the composition of the test gas is executed.

  Here, the detection of the composition of the test gas by the gas composition detection system 39 of the present embodiment will be described by taking the case of detecting the composition of natural gas as an example. Natural gas is composed of a plurality of components such as methane, propane, and butane, and the composition varies depending on the production area and purification time.

  In recent years, an engine that burns compressed natural gas (CNG) has been put into practical use. In order to improve the engine performance, fuel consumption performance, exhaust performance, and the like of such an engine, variation in the composition of natural gas is taken into consideration. It is desirable to perform fuel injection control.

  FIG. 2 is a graph showing changes in pressure when methane, propane and butane, which are main components of natural gas, are cooled with a single component. As shown in FIG. 2, these components have different boiling points. The boiling point of methane is −161.5 ° C., the boiling point of propane is −42.1 ° C., and the boiling point of butane is −0.5 ° C.

  When such a gas composed of a plurality of components having different boiling points is cooled, condensation starts from components having a high boiling point. FIG. 3 is a diagram exemplifying a change in pressure when natural gas mainly containing methane and mixed with a small amount of propane and butane is sealed as a test gas in a container 37 and cooled.

  In FIG. 3, the horizontal axis represents temperature, and the vertical axis represents pressure. As shown in FIG. 3, when the test gas composed of these three components is cooled, first, butane condensation starts (temperature T1).

  When the butane in the test gas is condensed, the pressure of the test gas in the container 37 is rapidly decreased (reduction from P1 to P1 '). The amount of pressure drop of the test gas due to the condensation of butane, that is, the difference (P1−P1 ′) between the pressure P1 when butane condensation starts and the pressure P1 ′ when butane condensation ends is This corresponds to the partial pressure of butane in the test gas in the state before the condensation.

Therefore, based on this pressure drop amount (P1-P1 ′), the ratio C1 (volume%) of butane in the original test gas can be expressed by the following equation.

  When the test gas is further cooled after butane has condensed, propane then begins to condense (temperature T2). As in the case of butane condensation, the pressure of the test gas in the container 37 rapidly decreases due to the condensation of propane in the test gas (from P2 to P2 ').

The pressure drop due to propane condensation (P2-P2 ′) corresponds to the partial pressure of propane in the test gas after butane has condensed. Therefore, based on this pressure drop amount (P2-P2 ′), the propane ratio C2 in the original test gas (the test gas before butane is condensed) is calculated using the butane ratio C1 calculated by Equation 1. Can be represented by the following formula.

Here, when butane (or propane) begins to condense, the pressure of the test gas decreases and the boiling point of butane (or propane) decreases, so the time between butane (or propane) starts to condense and the condensation ends Although the pressure change is not parallel to the vertical axis as shown in FIG. 3, the component composition of the test gas is mostly methane, and the proportion of other propane and butane is small.
It is possible to express the proportion of butane and propane by the above formulas 1 and 2.

In this example, since the test gas is a mixed gas of three components of methane, propane and butane, all the remainder is methane, and the ratio C3 of methane in the original test gas is the ratio C1 of butane calculated by Equation 1 and Using the propane ratio C2 calculated by Equation 2, it can be expressed by the following equation.

  Thus, when a certain component in the test gas is condensed in the process of cooling the test gas composed of a plurality of components, a rapid pressure drop occurs. Therefore, the pressure change in the container 37 during the cooling process is constantly monitored, When a significant pressure drop is detected (when a change appears in the temperature-pressure characteristics), it can be determined that a certain component in the test gas has started to condense.

  When it is detected that this sudden pressure change has ended, it can be determined that the condensation of the component has ended. From the pressure drop amount between these two points, the ratio of the component in the original test gas can be calculated as described above.

  The temperature at which a sudden pressure drop is detected corresponds to the boiling point of the condensed component. Therefore, the condensed component can be specified based on the pressure and temperature when a sudden pressure drop is detected. Data on the relationship between the pressure and temperature at the time of condensation and the component are stored in the ROM in the controller 36, and the condensed component can be specified by referring to this data.

  The controller 36 cools the test gas having a constant volume composed of a plurality of components introduced into the container 37 by the cooling device 31, and the test gas in the container 37 generated by the condensation of each component in the test gas in the cooling process. A sudden pressure drop (change in temperature characteristics of pressure change) is detected, and the condensed component is identified based on the temperature of the test gas in the container 37 when the sudden pressure drop occurs, and the pressure drop The composition of the test gas is detected by calculating the proportion of the condensed component in the test gas based on the amount.

  The test gas is introduced from the end of the introduction passage 29 opposite to the end connected to the container 37. When the test gas is introduced into the container 37, the controller 36 controls these two on-off valves so that the introduction passage on-off valve 30 is opened and the discharge passage on-off valve 34 is closed.

  When the test gas is introduced into the container 37, the controller 36 closes the introduction passage opening / closing valve 30 and closes both the introduction passage opening / closing valve 30 and the discharge passage opening / closing valve 34. A test gas is sealed inside.

  The controller 36 starts cooling by the cooling device 31 in this state. When the component of the test gas that has the lowest boiling point is known in advance, as in the case of detecting the composition of the natural gas composed of the above three components, it is sufficient to cool it below the boiling point of that component. is there.

  Therefore, when detecting the composition of the natural gas composed of the above three components, the cooling device 31 only needs to be capable of cooling the test gas to the boiling point of methane. The cooling device 31 can be any type of cooling device. When the gas composition detection system 39 is mounted on an automobile, it is preferable to employ a cooling method that can make the size of the cooling device 31 as compact as possible.

  FIG. 4 is a flowchart showing the gas composition detection described above. The process represented by this flowchart is executed by the controller 36. Here, the process in the case of detecting the composition of the above-described three-component natural gas as a test gas will be described as an example.

  First, in step S101, the controller 36 opens the introduction passage opening / closing valve 30. At this time, the discharge passage opening / closing valve 34 is closed. As a result, the test gas is introduced into the container 37 from the introduction passage 29.

  Next, in step S102, the controller 36 detects the temperature and pressure of the test gas in the container 37, and stores them as a temperature initial value T0 and a pressure initial value P0. The controller 36 acquires the initial temperature value T0 based on the detection value input from the temperature sensor 32, and acquires the initial pressure value P0 based on the detection value input from the pressure sensor 33.

  In step S103, the controller 36 reads a single component state diagram map of methane, propane and butane. The state diagram map is a map that stores the relationship between the temperature and pressure and the state of each component (gas, liquid, solid), and is stored in the ROM of the controller 36. When detecting a composition other than the three-component natural gas described above, a single component state diagram map is provided for each component assumed as a component constituting the test gas.

  In step S104, the controller 36 closes the introduction passage opening / closing valve 30. As a result, the test gas having the temperature T0 and the pressure P0 is sealed in the container 37.

  In step S105, the controller 36 activates the cooling device 31 to start cooling the test gas, and in step S106, the controller 36 starts constant monitoring of the temperature and pressure of the test gas in the container 37. The controller 36 monitors the temperature of the test gas based on the detection value input from the temperature sensor 32, and monitors the pressure of the test gas based on the detection value input from the pressure sensor 33.

  In step S107, the controller 36 determines whether or not a change has been detected in the characteristics of the pressure change associated with cooling. When the slope of the pressure drop accompanying cooling becomes discontinuously steep, the controller 36 determines that there has been a change in the pressure change characteristic accompanying cooling, and starts condensing the temperature and pressure in the container 37 at that time. Take as temperature and pressure of the point. In FIG. 4, “Tn, Pn” means the temperature and pressure at the condensation start point of the n-th component having the highest boiling point among the components constituting the test gas.

  The determination of whether or not the slope of the pressure drop due to cooling has become discontinuously steep is, for example, by determining whether or not the difference between the previously calculated temperature drop and the slope of the pressure drop is greater than a predetermined value. It can be carried out. In order to suppress erroneous determination, the average values of the slope calculation values for several times may be compared.

  Further, the detection values of the constant monitor by the temperature sensor 32 and the pressure sensor 33 may be stored for a certain period, and a determination process of a system different from the constant monitor and the cooling process may be executed.

  In step S108, the controller 36 specifies the condensed component with reference to the state diagram map read in step S103 based on the temperature Tn and pressure Pn of the condensation start point acquired in step S107.

In step S109, the controller 36 determines whether or not a change has been detected in the characteristics of the pressure change associated with the condensation. When the slope of the pressure drop due to cooling becomes discontinuously slow, the controller 36 determines that the pressure change characteristic due to condensation has changed, and the pressure in the container 37 at that time is determined as the condensation end point. Get as pressure. Here, the pressure at the condensation end point of the nth component is Pn ′.

  The method for determining whether or not the slope of the pressure drop due to cooling has become discontinuously slow is the same as the determination method in step S107.

  In step S110, the controller 36 condenses the component from the difference between the pressure Pn at the condensation start point of the nth component acquired at step S107 and the pressure Pn ′ at the condensation end point of the nth component acquired at step S109. The pressure drop amount (Pn−Pn ′) due to is calculated.

Then, the ratio Cn (volume%) of the nth component in the test gas is calculated by the following formula.

  Here, Ck is the ratio of the k-th component in the test gas, and N is the number of components constituting the test gas. In the above example of three component natural gas, N = 3.

  In step S111, the controller 36 determines whether or not it has cooled to the boiling point of the component having the lowest boiling point among the components constituting the test gas. Here, since natural gas composed of methane, propane, and butane is described as an example, it is determined whether or not the gas has been cooled to the boiling point of methane.

  If it is determined that the boiling point of methane has not been reached, the controller 36 returns to step S106 and continues to cool the test gas and monitor the temperature and pressure. If it is determined that the boiling point of methane has been reached, the controller 36 proceeds to step S112 and ends the cooling of the test gas.

  In step S113, the discharge passage opening / closing valve 34 is opened and the test gas in the container 37 is discharged. The discharge passage opening / closing valve 34 is opened until the pressure in the container 37 becomes lower than the specified pressure, and the test gas in the container 37 is discharged to prepare for the next composition detection process (step S114).

  The controller 36 that executes the above processing functions as the “gas composition detection processing means” in the present invention. In particular, the controller 36 that performs opening / closing control of the introduction passage opening / closing valve 30 and the discharge passage opening / closing valve 34 functions as the “valve control means” in the present invention.

  By the above treatment, the composition of the test gas composed of a plurality of components can be detected. In the above flowchart, the case where the composition of natural gas known to be composed of three components is detected has been described as an example. However, the composition detection of natural gas composed of four components or more and other mixed gases also relates to this embodiment. This can be done by the gas composition detection system 39.

  According to the gas composition detection system 39 according to the present embodiment, the composition of the mixed gas can be detected with a simple configuration.

(Example 2)
The gas composition detection system 39 according to the first embodiment can be suitably incorporated in an engine control system that burns gas fuel such as natural gas. In the present embodiment, an embodiment in which the gas composition detection system 39 described in the first embodiment is incorporated in a control system for a gas fuel engine that burns natural gas will be described.

  FIG. 5 is a diagram showing a schematic configuration of an engine system using compressed natural gas (CNG) and gasoline as fuels according to this embodiment. The present invention can also be applied to an internal combustion engine that uses natural gas and petroleum gas as primary fuel, such as liquefied petroleum gas (LPG), and coal conversion gas and petroleum conversion gas as secondary fuel.

  In FIG. 5, an engine 1 is a vehicle drive engine that uses gasoline and CNG as fuel. The engine 1 has four cylinders 2. Each cylinder 2 is provided with a spark plug 3. Each cylinder 2 communicates with an intake passage 6 and an exhaust passage 7 via an intake port 4 and an exhaust port 5.

  Each intake port 4 is provided with a gasoline injector 8 for injecting gasoline and a CNG injector 9 (fuel injection device) for injecting CNG.

  Each gasoline injector 8 is connected to a gasoline delivery pipe 10. One end of a gasoline supply passage 12 is connected to the gasoline delivery pipe 10, and the other end of the gasoline supply passage 12 is connected to a gasoline tank 13.

  A feed pump 14 is installed in the gasoline supply passage 12. Gasoline is supplied from the gasoline tank 13 to the gasoline delivery pipe 10 via the gasoline supply passage 12, and further, gasoline is supplied from the gasoline delivery pipe 10 to each gasoline injector 8.

  Each CNG injector 9 is connected to a delivery pipe 11 for CNG that accumulates CNG. One end of a CNG supply passage 15 is connected to the CNG delivery pipe 11, and the other end of the CNG supply passage 15 is connected to a CNG tank 16. The CNG supply passage 15 is provided with a regulator 17 for adjusting the pressure of the CNG taken out from the CNG tank 16 and reducing the pressure.

  The CNG stored in the CNG tank 16 at a high pressure is decompressed by the regulator 17, and the CNG is supplied to the CNG delivery pipe 11 through the CNG supply passage 15. The CNG in the CNG delivery pipe 11 is distributed to each CNG injector 9.

  The CNG delivery pipe 11 is provided with a pressure sensor 23 that detects the pressure of the CNG in the CNG delivery pipe 11 and a temperature sensor 24 that detects the temperature of the CNG. Further, a pressure sensor 25 that detects the pressure of CNG in the CNG supply passage 15 and a temperature sensor 26 that detects the temperature of the CNG are also provided upstream of the regulator 17 in the CNG supply passage 15.

  In the intake passage 6, an air cleaner 18, an air flow meter 22, and a throttle valve 19 are installed in this order from the upstream side. The exhaust passage 7 is provided with an A / F sensor 27 that detects the air-fuel ratio of the exhaust. An exhaust purification catalyst 21 composed of a three-way catalyst or the like is installed downstream of the A / F sensor 27.

The engine 1 is provided with an electronic control unit (ECU) 20. The ECU 20 is a unit that controls the operating state of the engine 1 and the like. An air flow meter 22, pressure sensors 23 and 25, temperature sensors 24 and 26, and an A / F sensor 27 are electrically connected to the ECU 20.

  Further, a crank angle sensor 28 that detects the crank angle of the engine 1 is also electrically connected to the ECU 20. Output signals from the sensors are input to the ECU 20. The ECU 20 derives the engine speed of the engine 1 based on the output signal of the crank angle sensor 28.

  Further, the gasoline injectors 8, the CNG injectors 9, the feed pump 14, the regulator 17, and the throttle valve 19 are electrically connected to the ECU 20. These are controlled by the ECU 20.

  The engine 1 according to the present embodiment may be an engine that is operated using only CNG as a fuel, or may be an in-cylinder direct injection engine that directly injects fuel into a cylinder.

  In the gas fuel engine 1 having the above-described configuration, the gas composition detection system 39 described in the first embodiment is incorporated. That is, the introduction passage 29 is connected to the CNG supply passage 15 upstream from the regulator 17 so that a part of the high-pressure CNG in the CNG tank 16 can be introduced into the container 37 as a test gas.

  Further, the discharge passage 35 is connected to the intake passage 6 so that the test gas in the container 37 can be discharged to the intake passage 6. Thereby, the composition of CNG in the CNG tank 16 can be detected by the gas composition detection system 39.

  The engine 1 includes an alternator 42 (regenerative device) that can regenerate power by using kinetic energy of the vehicle when the vehicle decelerates, and a battery 41 that can store electric power generated by the alternator 42. It is configured to operate upon receiving power.

  By recovering the kinetic energy of the vehicle as electrical energy and using this to operate the cooling device 31 of the gas composition detection system 39, the gas composition detection system 39 is incorporated to detect the composition of CNG to achieve fuel efficiency. The influence of can be suppressed.

By setting the container 37 to a minute volume of, for example, about 10 cm ³ , it is possible to improve the mountability of the gas composition detection system 39 and to suppress the energy required for cooling the test gas.

  The controller 36 is configured to transmit the detected CNG composition information to the ECU 20, and the ECU 20 controls the CNG injection by the CNG injector 9 based on the CNG composition information input from the controller 36.

  FIG. 6 is a view showing a cross section of one cylinder 2 of the engine 1 having the above configuration. As shown in FIG. 6, a piston 44 is inserted into the cylinder 2 so as to be slidable in the vertical direction, and a combustion chamber 40 is defined by the inner wall surface of the cylinder 2 and the top surface of the piston 44. The combustion chamber 40 communicates with the intake port 4 and the exhaust port 5, and an intake valve 43 that opens and closes the intake port 4 and an exhaust valve 38 that opens and closes the exhaust port 5 are provided.

  The intake port 4 is provided with a gasoline injector 8 for injecting gasoline and a CNG injector 9 for injecting CNG. CNG in the CNG tank 16 is supplied to the CNG injector 9 via the CNG delivery pipe 11 and the CNG supply passage 15.

  An introduction passage 29 is connected to the CNG supply passage 15 upstream of the regulator 17, and a discharge passage 35 is connected to the intake passage 6.

  In the engine control system of the present embodiment, when it is detected that the CNG tank 16 is filled with CNG, the gas composition detection system 39 detects the composition of the filled CNG. Then, fuel injection by the CNG injector 9 is controlled based on the detected composition.

  As described above, since the composition of natural gas varies depending on the production area and refining time, when new CNG is filled, CNG having a composition different from that of CNG used for combustion is used for combustion. There is a possibility.

  According to the engine control system of the present embodiment, when a new CNG is replenished to the CNG tank 16, the composition is detected. Therefore, even if the composition of the CNG varies, a predetermined engine performance and fuel consumption can be obtained. It is possible to perform precise air-fuel ratio control so that performance and exhaust performance can be achieved.

  FIG. 7 is a flowchart showing engine control in the engine control system of this embodiment. The process of this flowchart is executed by the ECU 20. The execution timing may be executed periodically at regular intervals, or may be executed when the ignition is turned on.

  It is preferable to determine the execution timing so that this control is executed as soon as possible after the CNG tank 16 is filled with CNG.

  In step S201, the ECU 20 determines whether or not the CNG tank 16 has been filled with CNG after the gas composition detection system 39 previously detected the composition of CNG. This determination can be made based on a change in the residual pressure of the CNG tank 16 or the like.

  If it is determined in step S201 that the CNG tank 16 has been filled with CNG after the previous detection of the CNG composition by the gas composition detection system 39, the ECU 20 proceeds to step S202.

  When it is determined that the CNG is not charged, the ECU 20 proceeds to step S204, and executes the engine combustion control by continuously using the CNG composition information based on the engine combustion control so far. The ECU 20 that executes the process of step S201 functions as the “gas fuel filling detection means” in the present invention.

  In step S202, the ECU 20 executes the gas composition detection process described in FIG. At this time, it may be confirmed whether the battery 41 is charged with sufficient power to cool the battery 41 to the boiling point of methane.

  After executing the gas composition detection process of FIG. 4, the controller 36 transmits the detected CNG composition information to the ECU 20. The controller 36 that executes the process of step S202 functions as the “gas fuel composition detection means” in the present invention.

In step S203, the ECU 20 corrects the engine combustion control based on the CNG composition information received from the controller. This process includes correction of control parameters related to combustion, such as the fuel injection amount by the CNG injector 9 and the ignition timing by the spark plug 3.

  In this case, in the subsequent step S204, the ECU 20 executes engine combustion control using the control parameter corrected in step S203. The ECU 20 executing the processing of this step functions as the “combustion control means” in the present invention.

  By executing the processing described above, even in an engine that uses CNG as a fuel, which has a high possibility of variation in the component composition every time it is filled, combustion control is performed according to the composition of CNG provided for combustion. Therefore, it is possible to perform precise air-fuel ratio control in which engine performance, fuel consumption performance, exhaust performance, and the like satisfy predetermined requirements.

  In addition, although the structure which operates the cooling device 31 of the gas composition detection system 39 using regenerative energy was illustrated in the present Example, the cooling device 31 is not restricted to what cools using electrical energy, A cooling device The energy source for operating 31 is not limited to regenerative energy.

  Further, the timing at which the test gas whose composition has been detected is discharged to the intake passage 6 may be limited to a timing at which the discharged test gas does not affect the torque, such as during deceleration. Further, all functions of the controller 36 may be integrated in the ECU 20.

  Moreover, although the structure which takes out the test gas introduced into the gas composition detection system 39 from regulator 17 front was illustrated, the position which takes out test gas is not restricted to this. However, a higher initial pressure of the test gas is preferable from the viewpoint of fuel consumption because energy required for cooling can be reduced. The second embodiment described above is an example in which the gas composition detection system according to the present invention is incorporated into a control system for a vehicle driving engine using CNG and gasoline as fuel, but is not limited to a vehicle driving engine, and includes various generators and measuring instruments. The gas composition detection system according to the present invention can be applied to a control system for an engine that burns natural gas in this field, thereby enabling precise air-fuel ratio control.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder 3 ... Spark plug 4 ... Intake manifold 5 ... Exhaust manifold 6 ... Intake passage 7 ... Exhaust passage 8 ... Gasoline injector 9 ... CNG injector 10 .. gasoline delivery pipe 11 .. CNG delivery pipe 12 .. gasoline supply passage 13 .. gasoline tank 14 .. feed pump 15 .. CNG supply passage 16 .. CNG tank 17 .. regulator 18. Air cleaner 19 ・ ・ Throttle valve 20 ・ ・ ECU
21 .. Exhaust purification catalyst 22 .. Air flow meter 23 .. Pressure sensor 24 .. Temperature sensor 25 .. Pressure sensor 26 .. Temperature sensor 27 .. A / F sensor 28 .. Crank angle sensor 29. ..Inlet passage opening / closing valve 31..Cooling device 32..Temperature sensor 33..Pressure sensor 34..Drain passage opening / closing valve 35..Drain passage 36..Controller 37..Vessel 38..Exhaust valve 39 .. Composition detection system 40..Combustion chamber 41..Battery 42..Alternator 43..Intake valve

Claims (7)

  A test gas of a constant volume composed of a plurality of components is cooled, and a pressure drop caused by condensation of each component in the test gas is detected during the cooling process, and condensed based on the temperature at which the pressure drop occurs. A gas composition detection system that identifies a component and calculates a ratio of a condensed component in a test gas based on the pressure drop amount to detect a composition of the test gas. A gas composition detection system for detecting a composition of a test gas composed of a plurality of components,
A constant volume container;
A cooling device for cooling the test gas in the container;
Pressure detecting means for detecting the pressure of the test gas in the container;
Temperature detecting means for detecting the temperature of the test gas in the container;
A test gas is introduced into the container, the introduced test gas is cooled by the cooling device, and a pressure drop caused by condensation of each component in the test gas in the course of the cooling is detected by the pressure detection means; The temperature at which the pressure drop is detected is detected by the temperature detecting means, the condensed component is specified based on the detected temperature, and the condensed component of the test gas is determined based on the pressure drop amount. Gas composition detection processing means for calculating a ratio;
A gas composition detection system comprising: In claim 2,
An introduction passage for introducing a test gas into the container;
A discharge passage for discharging the test gas in the container;
An introduction passage opening and closing valve for opening and closing the introduction passage;
A discharge passage opening / closing valve for opening and closing the discharge passage;
With
The gas composition detection processing means includes valve control means for controlling the introduction passage opening / closing valve and the discharge passage opening / closing valve,
The valve control means includes
When introducing the test gas into the container, control to open the introduction passage on-off valve and close the discharge passage on-off valve,
When cooling the test gas by the cooling device, control to close the introduction passage on-off valve and close the discharge passage on-off valve,
When the detection of the composition of the test gas is completed, the introduction passage opening / closing valve and the discharge passage opening / closing valve are controlled to close the introduction passage opening / closing valve and open the discharge passage opening / closing valve. Gas composition detection system. A control system for an engine that burns gaseous fuel, comprising the gas composition detection system according to any one of claims 1 to 3.
Gas fuel composition detection means for detecting the composition of the gas fuel supplied to the fuel injection device of the engine by the gas composition detection system;
Combustion control means for performing combustion control of the engine based on the composition detected by the gas fuel composition detection means;
An engine control system comprising: In claim 4,
Gas fuel filling detection means for detecting that the gas fuel is filled in the storage means for storing the gas fuel,
The gas fuel composition detection means detects the composition of the filled gas fuel when the gas fuel filling detection means detects that the storage means is filled with gas fuel. Control system. In claim 4 or 5,
The gas fuel composition detection means performs composition detection by the gas composition detection system using a gas fuel upstream of a regulator that adjusts the pressure of the gas fuel supplied to the fuel injection device as a test gas. Control system. In any one of Claims 4-6,
The engine is a vehicle driving engine mounted on a vehicle,
A regenerative device for recovering the kinetic energy of the vehicle as regenerative energy;
The gas composition detection system cools the test gas with the regenerative energy collected by the regenerative device, and controls the engine.

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