JP2008121548A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve startability in cold starting, in an internal combustion engine such as an engine of an automobile. <P>SOLUTION: This control device of the internal combustion engine has a first storage means 310 storing fuel supplied for combustion of the internal combustion engine, a reforming means 320 generating reformed fuel by applying reforming processing to at least partial fuel among this stored fuel, and a second storage means 330 storing this generated reformed fuel, and also has a control means 100 controlling the reforming means so as to selectively apply the reforming processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine mounted on, for example, an alcohol fuel flexible fuel vehicle (FFV).

  Such a control device for an internal combustion engine is mounted on, for example, a flexible fuel vehicle. This flexible fuel vehicle can run even if gasoline fuel and alcohol fuel are mixed in various ratios. However, alcohol fuel is less likely to vaporize at lower temperatures than gasoline fuel. Therefore, the startability at the time of cold start may be reduced.

  In order to deal with such a problem, for example, a technique as disclosed in Patent Document 1 below has been proposed.

  Specifically, a technique has been proposed in which a sub fuel tank is provided separately from the main fuel tank, and the fuel in the sub fuel tank is heated by a heating means such as a heater based on the alcohol concentration of the fuel and the engine temperature (patent) Reference 1). According to this technique, the volatility of alcohol is increased, and an improvement in startability is expected.

  Here, the sub fuel tank is a fuel tank that plays an auxiliary role with respect to the main fuel tank, and various uses thereof have been proposed. For example, when returning surplus fuel in an internal combustion engine to a main fuel tank and a sub fuel tank, a technique for determining a distribution ratio between both fuel tanks based on the fuel temperature of the sub fuel tank has been proposed (Patent Document 2). reference). According to this technology, fuel vapor can be prevented from evaporating.

JP-A-5-149223 JP 7-49066 A

  However, for example, the following problems may occur in the techniques disclosed in Patent Documents 1 and 2 described above.

  That is, in the technique disclosed in Patent Document 1, it takes a certain amount of time and electric power to sufficiently heat the fuel in the sub fuel tank, and depending on the properties of the fuel, the startability may not be sufficiently exhibited. This tendency is remarkable when a heavy fuel or a fuel having a large influence on the cold start is used as the fuel.

  Alternatively, the technique disclosed in Patent Document 2 prevents evaporation of fuel vapor, but does not improve startability.

  The present invention has been made in view of, for example, the above-described problems. Control of an internal combustion engine that can suitably improve startability even when using fuel with relatively low startability, such as heavy fuel. It is an object to provide an apparatus.

  In order to solve the above-described problem, a control device for an internal combustion engine according to the present invention is modified with respect to at least a part of the first storage means for storing fuel to be used for combustion of the internal combustion engine and the stored fuel. Reforming means for generating reformed fuel by performing quality treatment, second storage means for storing the generated reformed fuel, and selectively modifying the reforming process according to the necessity of the reforming process And a control means for controlling the reforming means.

  According to the control apparatus for an internal combustion engine according to the present invention, the startability can be suitably improved even when a fuel having a relatively low startability such as heavy fuel is used as follows.

  That is, first, fuel to be used for combustion of the internal combustion engine is stored by first storage means such as a main fuel tank. “Fuel” is, for example, gasoline fuel or a mixed fuel of gasoline and alcohol.

  Then, a reforming process is performed on at least a part of the stored fuel by a reforming unit made of, for example, a rhodium-based reforming catalyst, and a reformed fuel is generated. The “reforming process” is a process that increases or decreases the fuel startability, in other words, a process that facilitates vaporization of the fuel. For example, the weight of the fuel is relatively reduced to make it lighter, Or the process which reduces the alcohol concentration of a fuel is said. A “reformed fuel” is a fuel that has been “reformed” with respect to a normal fuel. For example, it is a heavy liquid phase fuel (hereinafter referred to as “heavy fuel”) that contains many high-boiling components. The reformed fuel is also a light gas phase fuel (hereinafter also referred to as “light fuel”) that contains many low-boiling components. Note that “heavy” or “light” as used herein is not an absolute relationship, but is a relative relationship that is established based on a comparison between heavy fuel and light fuel.

  The produced reformed fuel is stored by a second storage means such as a sub fuel tank. The stored reformed fuel is used for combustion at the time of cold start of the internal combustion engine, for example.

  Here, it is assumed that the fuel stored in the second storage means is a fuel that has not been subjected to the reforming process, for example, a heavy fuel similar to the fuel stored in the first storage means. Even if the internal combustion engine is cold-started in this state, the fuel stored in both storage means is heavy fuel, so the degree of vaporization is small compared to normal fuel, and there is room for improvement in startability. There is. At this time, even if the second storage means is heated with the heavy fuel and the vaporization is promoted, an appropriate time and electric power are required for sufficient heating.

  However, according to the control apparatus for an internal combustion engine according to the present invention, the reforming means is controlled by, for example, an ECU such that the reforming process is selectively performed according to the degree of necessity of the reforming process as described above. Controlled by means. The “necessity of the reforming process” here is a qualitative or quantitative measure indicating how much the reforming process is required. For example, the reforming process “necessary”. Alternatively, it may be indicated by a binary value indicating “not necessary”, or may be indicated by a more detailed scale. For example, when it is determined that the reforming process is “necessary” based on various conditions such as the remaining amount of reformed fuel or the degree of heavyness of fuel that can be measured or specified directly or indirectly The reforming process is selectively performed on at least a part of the fuel stored in the first storage means. In order to perform the reforming process selectively as described above, the reforming unit opens and closes a receiving port for receiving fuel from the first storage unit by using a valve such as a butterfly valve.

  Such a reforming process typically starts a series of combustion operations at the time of operation or combustion of the internal combustion engine, for example, the nth (where n is a natural number) times, whereas This is performed during a series of combustion operations preceding or preceding the n-1th combustion operation. However, the reforming process does not have to be performed during the normal combustion operation.

  As a result, a reformed fuel having a high startability as compared with heavy fuel can be generated and used as appropriate. Therefore, even when a heavy fuel having a relatively low startability is used, the startability can be preferably improved. At this time, the reformed fuel can be generated and stored in advance prior to the cold start, so that it does not take much time and is very effective in practice compared to the case where it is heated at the start.

  In one aspect of the control apparatus for an internal combustion engine according to the present invention, in order to solve the above problem, the reforming means reduces the degree of heavyness of the at least part of the fuel as the reforming process.

  According to this aspect, a light fuel can be obtained and stored as a reformed fuel. More specifically, the reforming means reduces the degree of heavyness of at least a part of the fuel as the reforming process. Here, the fuel is, for example, a hydrocarbon fuel. The reforming catalyst is, for example, a catalyst in which rhodium is supported on zirconia. Then, the hydrocarbon-based fuel and air are reacted by the reforming catalyst, and reformed fuel containing CO and H 2 is generated (see, for example, Japanese Patent Application Laid-Open No. 2006-36562 by the present applicant). In this way, a light fuel can be obtained and stored as a reformed fuel.

  In another aspect of the control device for an internal combustion engine according to the present invention, in order to solve the above problem, the control device further includes an exhaust pipe through which the exhaust gas accompanying the combustion passes, and the reforming means is thermally connected to the exhaust pipe. Touch.

  According to this aspect, the reforming catalyst built in the reforming means can be activated with high energy efficiency. More specifically, exhaust gas accompanying combustion passes through the exhaust pipe and is discharged to the outside. The reforming means is in thermal contact with the exhaust pipe. “Thermal contact” indicates a state in which heat energy (that is, waste heat) can be transferred directly or indirectly. For example, the reforming means is provided so as to at least partially cover the exhaust pipe in the pipe line of the exhaust pipe. If the reforming means is lower in temperature than the exhaust gas passing through the exhaust pipe, the reforming means receives thermal energy, and the temperature of the built-in reforming catalyst is changed to the activation temperature (for example, 600 degrees). ). At this time, since no heating means such as a heater is required, energy efficiency is very good.

  In another aspect of the control device for an internal combustion engine according to the present invention, in order to solve the above problem, a temperature specifying means for specifying the temperature of the internal combustion engine, and the first storage means based on at least the specified temperature. And a supply means for selectively supplying one of the fuel stored by the second storage means and the reformed fuel stored by the second storage means to the combustion chamber of the internal combustion engine.

  According to this aspect, it is possible to properly use the fuel according to the temperature of the internal combustion engine. More specifically, the temperature of the internal combustion engine is specified by temperature specifying means such as a water temperature sensor. Based on at least the temperature specified in this way, the fuel stored in the first storage means and the reformed fuel stored in the second storage means are supplied by, for example, a supply means including a fuel pipe and a pipe switching valve. Either one of the fuels is selectively supplied to the combustion chamber of the internal combustion engine. For example, when the specified temperature is relatively high, it is assumed that the fuel is easily vaporized, so that the fuel stored by the first storage means is supplied, and conversely, the specified temperature is relatively low. Therefore, the reformed fuel is supplied because it is assumed that the fuel is not easily vaporized. In this way, it is possible to properly use the fuel according to the temperature of the internal combustion engine. Moreover, since it is possible to avoid performing the reforming process more than necessary, the energy efficiency is very good.

  In the aspect including the temperature specifying means and the supply means, the supply means is at the start of the internal combustion engine, and when the specified temperature falls below a predetermined temperature threshold, the reformed fuel is You may supply to the said combustion chamber.

  According to this aspect, it is possible to improve the startability particularly during the cold start. More specifically, when the internal combustion engine is started and the specified temperature falls below a predetermined temperature threshold (that is, when the temperature is equal to or lower than the predetermined temperature threshold or lower than the predetermined temperature threshold), in other words In this case, it is determined whether or not it is during cold start. Here, the “predetermined temperature threshold” is a boundary temperature for determining whether or not it is “cold”. For example, based on the relationship between the temperature of the internal combustion engine and the degree of fuel vaporization, The temperature at which deterioration of startability exceeds an allowable range when heavy fuel is used may be determined in advance by empirical, experimental, or simulation. In the cold start time, the reforming fuel is supplied to the combustion chamber by the supply means. Therefore, the startability at the cold start can be improved.

  In another aspect of the control device for an internal combustion engine according to the present invention, in order to solve the above-described problem, the control device further includes a remaining amount specifying unit that specifies a remaining amount of the reformed fuel stored in the second storage unit, The control unit controls the reforming unit to perform the reforming process when the specified remaining amount is below a predetermined target storage amount.

  According to this aspect, stable startability is guaranteed. More specifically, the remaining amount of the reformed fuel stored in the second storage unit is specified regularly or irregularly by a remaining amount specifying unit such as a fuel sensor. Here, it is determined whether or not the specified remaining amount is below a predetermined target storage amount. Here, the “remaining amount of reformed fuel stored in the second storage means” quantitatively indicates “necessity of reforming process”. For example, the smaller the remaining amount of the reformed fuel stored in the second storage means, the higher the necessity for the reforming process. The “predetermined target storage amount” may be determined in advance experimentally or by simulation as the storage amount of the reformed fuel required at the next cold start. Then, when the specified remaining amount is less than the predetermined target storage amount, the reforming unit is controlled by the control unit so as to perform the reforming process. Typically, such a reforming process, for example, starts the n-th series of combustion operations, but corresponds to the (n-1) -th time preceding or preceding the series of combustion operations. Performed during a series of combustion operations. Accordingly, a shortage of reformed fuel at the next cold start or the like can be avoided, so that stable startability is guaranteed.

  In another aspect of the control device for an internal combustion engine according to the present invention, in order to solve the above-described problem, the control device further includes first heavy weight specifying means for specifying a heavy degree of the fuel stored by the first storage means, The control means controls the reforming means to perform the reforming process when the degree of heavyness of the specified fuel exceeds a predetermined first weight degree.

  According to this aspect, even if the fuel stored by the first storage means is a heavy fuel, it is possible to avoid a decrease in startability. More specifically, the degree of heavyness of the fuel stored by the first storage means is specified by a first heavy specifying means such as an air-fuel ratio sensor and an ECU. Here, “the degree of heavyness of the fuel stored by the first storage means” quantitatively indicates “necessity of reforming treatment”. For example, it is considered that the higher the degree of heaviness of the fuel stored by the first storage means, the higher the necessity for the reforming process. The “heavy degree” of the fuel is a scale indicating how heavy the fuel is, or how much the degree of vaporization is smaller than that of a normal fuel. Such a degree of heavyness may be specified directly by, for example, detecting a high-boiling component or alcohol concentration of the fuel stored by the first storage means, or at the time of cold start, air-fuel ratio feedback You may specify indirectly from the variation | change_quantity of correction amount. When the fuel heavy degree specified in this way exceeds the predetermined first heavy degree (that is, when it is equal to or higher than the predetermined first heavy degree or higher than the predetermined first heavy degree) ) Is controlled by the control means so as to perform the reforming process. Therefore, even if the fuel stored by the first storage means is a heavy fuel, it is possible to avoid a decrease in startability.

  In another aspect of the control device for an internal combustion engine according to the present invention, in order to solve the above-described problem, a second heavy weight specifying means for specifying a heavy degree of the reformed fuel stored in the second storage means is further provided. And the control means performs the reforming process to replace the reformed fuel stored in the second storage means when the specified heavy degree exceeds a predetermined second heavy degree. The reforming means is controlled so as to be applied again.

  According to this aspect, it is possible to suitably cope with the case where the properties of the fuel change with time. More specifically, generally, the low boiling point volatile component in the fuel component spontaneously evaporates, so that the properties of the fuel are not necessarily constant over time. For this reason, even if the reformed fuel stored in the second storage means is light immediately after the reforming process, it can become heavy over time. Even if such reformed fuel is used, the startability can no longer be improved. However, according to this aspect, the degree of heavyness of the reformed fuel stored in the second storage unit is specified by the second heavy specifying unit such as an air-fuel ratio sensor and an ECU. And when the heavy degree specified in this way exceeds the predetermined second heavy degree (that is, when it is equal to or higher than the predetermined second heavy degree or higher than the predetermined second heavy degree). The reforming means is controlled by the control means so that the reforming process is performed again to replace the reformed fuel stored in the second storage means. Therefore, even when the internal combustion engine such as a plug-in hybrid vehicle has few opportunities to start, the reformed fuel stored in the second storage means does not exceed the predetermined second heavy degree, in other words, it is light. To be kept. As a result, even when the properties of the fuel change with time, it is possible to cope with it suitably. At this time, since it is possible to avoid performing the reforming process more than necessary, the energy efficiency is very good.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as the best mode for carrying out the invention.

(1) 1st Embodiment The structure and operation | movement process of the control apparatus of the internal combustion engine which concern on 1st Embodiment are demonstrated with reference to FIGS.

(1-1) Configuration First, the configuration of an engine 200 that is a specific example of the internal combustion engine according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of the control device for the internal combustion engine according to the first embodiment of the present invention.

  In FIG. 1, an engine 200 includes a cylinder 201, an intake pipe 206, an injector 207, an intake valve 208, a catalyst 222, an air-fuel ratio sensor 221, a main fuel tank 310, a reformer 320, a sub fuel tank 330, a main fuel sensor 225, A sub fuel sensor 226, a switching valve 341, a switching valve 342, and the control device 100 are provided. Each of these is configured as follows.

  The cylinder 201 is configured to explode the air-fuel mixture by ignition of the spark plug 202 and to convert the reciprocating motion of the piston 203 generated according to the explosive force into the rotational motion of the crankshaft 205 via the connection rod 204. Has been. Around the cylinder 201, various sensors such as a water temperature sensor 220 for detecting the temperature of the cooling water, a crank position sensor 218 for detecting the crank angle, and a knock sensor 219 for detecting the presence or absence of knocking are disposed. . The output of each sensor is supplied to the control device 100 as a corresponding detection signal. The water temperature sensor 220 is an example of the “temperature specifying means” according to the present invention.

  The intake pipe 206 is configured to be able to suck air into the cylinder 201. The intake pipe 206 is provided with a throttle valve (not shown), and the amount of intake air is appropriately adjusted based on the required torque or the like.

  The injector 207 is configured to be able to inject fuel supplied from the main fuel tank 310 or the sub fuel tank 330 into the intake pipe 206 in accordance with control of the control device 100. The injected fuel is mixed with the air sucked through the intake pipe 206 to become an air-fuel mixture and is used for combustion in the cylinder 201.

  The intake valve 208 is configured to be able to control the communication state between the inside of the cylinder 201 and the intake pipe 206. The exhaust valve 209 is configured to be able to control the communication state between the cylinder 201 and the exhaust pipe 210. The air-fuel mixture combusted inside the cylinder 201 becomes exhaust gas, passes through the exhaust valve 209 that opens and closes in conjunction with the opening and closing of the intake valve 208, and is exhausted through the exhaust pipe 210. These opening / closing timings are adjusted by, for example, a well-known variable valve timing-intelligent system (VVT-i).

  The catalyst 222 is a catalyst having a noble metal such as platinum or rhodium as an active component, and is provided in a pipe line of the exhaust pipe 210, for example. The catalyst 222 has a function of removing nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), and the like in the exhaust gas. Since the exhaust gas purifying ability of the catalyst 222 changes depending on the temperature, it is necessary to raise the temperature of the catalyst 222 to the activation temperature, for example, at the time of cold start.

  The air-fuel ratio sensor 221 is an example of the “first heavy specifying means” and the “second heavy specifying means” according to the present invention. The air-fuel ratio sensor 221 is made of, for example, a zirconia solid electrolyte, and is installed in a pipe line of the exhaust pipe 210 to detect an air-fuel ratio (A / F) in the exhaust gas and to send a detection signal to the control device 100. , The air-fuel ratio feedback correction is performed, or the variation amount of the air-fuel ratio is specified. From the variation amount of the air-fuel ratio, the degree of heavy fuel is indirectly specified.

  The main fuel tank 310 is an example of the “first storage unit” according to the present invention, and is a main fuel tank that stores fuel to be used for combustion of the engine 200. The fuel supplied from the fuel supply port 311 is first replenished to the main fuel tank 310. The stored fuel is sucked up by a pump (not shown) and supplied to the injector 207 or the reformer 320.

  The reformer 320 is an example of the “reforming means” according to the present invention, and the reformed fuel is supplied by subjecting at least a part of the fuel supplied from the main fuel tank 310 to reforming. At the same time, the generated reformed fuel is supplied to the sub fuel tank 330. Here, the “reforming process” is a process that increases or decreases the startability of the fuel, and specifically, a process that relatively reduces the degree of fuel heavyness, or the alcohol concentration of the fuel. Is a process of relatively lowering. In order to realize this reforming process, the reformer 320 includes, for example, a rhodium-based reforming catalyst. And in order to activate this reforming catalyst efficiently, the reformer 320 is provided in the pipe line of the exhaust pipe 210. Therefore, it is possible to receive the heat energy of the relatively high-temperature exhaust gas that passes through the exhaust pipe 210 and raise the catalyst temperature to the activation temperature while suppressing energy loss as much as possible.

  The sub fuel tank 330 is an example of the “second storage unit” according to the present invention, and is an ancillary fuel tank that stores the reformed fuel generated by the reformer 320. The stored fuel is sucked up by a pump (not shown) and supplied to the injector 207.

  The main fuel sensor 225 is installed in the main fuel tank 310 and detects the remaining amount of fuel and supplies a detection signal corresponding to the remaining amount to the control device 100.

  The sub fuel sensor 226 is an example of the “remaining amount specifying means” according to the present invention, and is installed in the sub fuel tank 226 to detect the remaining amount of fuel and to send a detection signal corresponding to the remaining amount to the control device 100. And supply.

  Here, there are mainly two paths through which the stored fuel reaches the injector 207. That is, a route not passing through the sub fuel tank 330 (main fuel route 321) and a route passing therethrough (sub fuel route 322). These routes are examples of the “supplying unit” according to the present invention.

  The switching valve 341 is, for example, an electric butterfly valve that operates under the control of the control device 100, and the reformer 320 converts the fuel stored in the main fuel tank 310 that needs to be reformed by opening and closing thereof. Guide to.

  The switching valve 342 is, for example, an electric three-way valve that operates under the control of the control device 100. The configuration of the fuel supplied to the injector 207, that is, the fuel supplied via the main fuel path 321 and the sub fuel The distribution with the reformed fuel supplied via the path 322 is changed.

  The control device 100 is an example of the “control means” according to the present invention, and preferably comprises an ECU, a known central processing unit (CPU), and a read-only memory (Read Only Memory) that stores a control program. : ROM), a random-access memory (RAM) that stores various data, and the like. Furthermore, it is connected via a bus to an input port that receives input signals from various sensors such as the air-fuel ratio sensor 221 and an output port that sends control signals to various actuators such as the switching valve 341 or the switching valve 342. .

(1-2) Operation Process Next, the operation process of the control apparatus for an internal combustion engine according to the present embodiment configured as described above will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a flowchart showing the reforming process performed by the control device for the internal combustion engine according to the first embodiment.

  In FIG. 2, first, prior to the reforming process, it is determined by the control device 100 whether or not the engine 200 is in operation (step S100).

  Here, when it is determined that the engine 200 is in operation (step S100: Yes), the exhaust gas is discharged through the exhaust pipe 210 regularly or irregularly. In response to the exhaust energy of the exhaust gas, the reforming catalyst of the reformer 320 is activated.

  Subsequently, whether or not the reforming process is necessary for the fuel stored in the main fuel tank 310 or the sub fuel tank 330 is determined by the control device 100 that receives detection signals of various sensors ( Step S101). For example, whether or not the reforming process is necessary because the fuel stored in the sub fuel tank 330 is heavy and the reformed fuel stored in the sub fuel tank 330 is very small. Is determined.

  Here, when it is determined that the reforming is necessary (step S101: Yes), the reformer 320 performs the reforming process (step S102). More specifically, the opening degree of the switching valve 341 is brought close to the fully open side by the control device 100, and at least a part of the fuel stored in the main fuel tank 310 is guided to the activated reformer 320. Is done. As a result, the reformed fuel is suitably generated.

  The reformed fuel generated in this way is supplemented to the sub fuel tank 330 via the sub fuel path 322 (step S103). Therefore, for example, when the engine 200 is cold started, the reformed fuel can be used as necessary.

  When it is determined that the engine 200 is not in operation (step S100: No), or when it is determined that no reforming is necessary (step S101: No), exhaust heat cannot be used in the reforming process. Alternatively, since there is no need for an imminent reforming process, the reforming process is not performed and a standby state is entered.

  An example of a process for properly using the reformed fuel generated as described above will be described with reference to FIG. 3 in addition to FIG. FIG. 3 is a flowchart showing the reformed fuel use determination processing by the internal combustion engine control apparatus according to the first embodiment.

  In FIG. 3, first, it is determined by the control device 100 whether or not the engine 200 is being started (step S111). For example, it is determined whether or not it is within a predetermined period after starting.

  Here, when it is determined that the engine is at the time of starting (step S111: Yes), the water temperature is detected by the water temperature sensor 220 (step S112). And it is determined by the control apparatus 100 whether the detected water temperature is lower than a predetermined temperature threshold value (step S113).

  Here, when it is determined that the detected water temperature is lower than the predetermined temperature threshold (step S113: Yes), it is a cold start time, so it is preferable to use a fuel with good startability. Therefore, the vehicle travels using the reformed fuel in the sub fuel tank 330 (step S114). More specifically, the control device is configured such that the fuel supplied to the injector 207 has more reformed fuel supplied via the sub fuel path 322 than fuel supplied via the main fuel path 321. By 100, the opening degree of the switching valve 342 is controlled.

  In addition, when it is determined that it is not at the time of starting (step S111: No), or when it is determined that the detected water temperature is not lower than the predetermined temperature threshold even at the time of starting (step S113: No). Since it is considered that the fuel is warmed to such an extent that the startability of the fuel does not become a problem, the vehicle travels using the fuel in the main fuel tank (step S115).

According to the embodiment described above, the reformed fuel is appropriately generated as shown in FIG. 2 based on the configuration shown in FIG. For example, in a situation where there is a concern about startability deterioration such as during cold start, reformed fuel is selectively used as shown in FIG. Therefore, even when the fuel stored in the main fuel tank 310 has a relatively low startability such as heavy fuel, the startability can be preferably improved, which is very advantageous in practice.
(2) Second Embodiment Next, the configuration and operation processing of the control device for an internal combustion engine according to the second embodiment will be described with reference to FIG. 4 in addition to FIG. In particular, the present embodiment is an embodiment for preventing a situation where the reformed fuel is insufficient at the next cold start. The basic configuration is the same as the configuration shown in FIG. 1, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate. FIG. 4 is a flowchart showing the operation process of the control device for the internal combustion engine according to the second embodiment.

  In FIG. 4, for example, during operation of the engine 200, the property of the fuel stored in the main fuel tank 310 is specified regularly or irregularly (step S201). For example, whether the fuel is heavy or light at the time of refueling is recorded in a memory, and the property is specified by reading the recorded information afterwards.

  Then, it is determined whether the fuel stored in the main fuel tank 310 is heavy (step S202). Here, the determination as to whether or not the fuel property is heavy is based on the determination as to whether or not the degree of vaporization is small with respect to a normal fuel. For example, at the time of cold start, when the fuel injection amount or the fuel injection time with respect to the intake air amount is larger than the normal time, it is determined that the fuel property is heavy. Alternatively, at the time of cold start, when the fluctuation amount is not within the predetermined fluctuation amount from the history of the air-fuel ratio feedback correction amount, that is, when the combustion is unstable, it is determined that the fuel property is heavy.

  Here, when it is determined that the fuel stored in the main fuel tank 310 is not heavy (step S202: No), in other words, when it is light, startability deteriorates due to the properties of the fuel. Therefore, the reforming process is not performed and the vehicle is in a normal traveling state (step S209).

  Here, when it is determined that the main fuel is heavy (step S202: Yes), it is necessary to use the reformed fuel in order to improve the startability at the cold start. Therefore, the remaining amount of the reformed fuel stored in the sub fuel tank 330 is detected by the sub fuel sensor 226 (step S203), and it is determined whether the remaining amount is below the target storage amount (step S203). S204).

  Here, when the remaining amount of the reformed fuel is lower than the target storage amount (step S204: Yes), there is a possibility that the reformed fuel necessary for the next cold start is insufficient. Therefore, the following processing is performed to replenish the reformed fuel. That is, the engine 200 is started (step S205). Then, waste heat is recovered from the exhaust gas (step S206). Specifically, the exhaust gas is exhausted through the exhaust pipe 210 regularly or irregularly, and the reforming catalyst of the reformer 320 receives the exhaust energy (that is, waste heat) of the exhaust gas. Activated. When the reforming catalyst is ready, the reforming process is performed on the fuel stored in the main fuel tank 310 and guided to the reformer 320 (step S207). More specifically, the opening degree of the switching valve 341 is brought close to the fully open side by the control device 100, and at least a part of the fuel stored in the main fuel tank 310 is guided to the activated reformer 320. Is done. As a result, the reformed fuel is suitably generated. The reformed fuel generated in this way is replenished to the sub fuel tank 330 via the sub fuel path 322 (step S208). This reforming process is continued until the remaining amount of the reformed fuel reaches or exceeds the target storage (step S204: No). Therefore, the reformed fuel can be used for the next cold start, and the startability can be improved. As described above, when the reformed fuel is replenished, a normal running state is set (step S209).

According to the embodiment described above, the reformed fuel is appropriately generated based on the remaining amount of the reformed fuel stored in the sub fuel tank 330. Therefore, it is possible to prevent a situation where the reformed fuel is insufficient at the next cold start. Thus, the control apparatus for an internal combustion engine according to the present embodiment is very effective in practice because startability can be guaranteed.
(3) Third Embodiment Next, the configuration and operation processing of a control device for an internal combustion engine according to a third embodiment will be described with reference to FIG. 5 in addition to FIGS. FIG. 5 is a flowchart showing an operation process of the control device for the internal combustion engine according to the third embodiment.
The present embodiment is particularly effective for ensuring startability even when the reformed fuel that should have been subjected to the reforming process returns to heavy fuel due to factors such as aging. It is a form. The basic configuration is the same as the configuration shown in FIG. 1, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

  In FIG. 5, for example, when the engine 200 is operating or stopped, the property of the reformed fuel stored in the sub fuel tank 330 is specified regularly or irregularly (step S301). Here, the determination as to whether or not the property of the reformed fuel is heavy is similar to the case of determining the property of the fuel stored in the main fuel tank 310 described above, and the degree of vaporization with respect to normal fuel. It may be performed based on the determination of whether or not is small. Or you may perform based on determination whether the period which has passed since the last modification | reformation process exceeds a predetermined period.

  Then, it is determined whether or not the degree of heavyness of the reformed fuel stored in the sub fuel tank 330 is greater than the predetermined degree of heavyness (step S302). Here, when it is not determined that the degree of heavyness of the reformed fuel is greater than the predetermined degree of heavyness (step S302: No), the reformed fuel that has undergone the reforming process is still a light fuel. Therefore, if this reformed fuel is used at the time of cold start, startability can be improved.

  On the other hand, when it is determined that the degree of heavyness of the reformed fuel is larger than the predetermined degree of heavyness (step S302: Yes), the reformed fuel that should have undergone the reforming process changes, for example, over time. There is a possibility that it has returned to heavy fuel due to factors such as. If a fuel with such properties is used during cold start, the startability may be deteriorated.

  In order to avoid such a situation, the reformed fuel larger than the predetermined degree of heavyness is used during normal running when the engine 200 is sufficiently warmed, for example, other than during cold start (step S303). Alternatively, a return path (not shown) may be provided between the main fuel tank 310 and the sub fuel tank 330, and the reformed fuel having a larger degree of heavyness may be returned to the main fuel tank 310. In any case, it is preferable to drive out reformed fuel larger than the predetermined degree of heavyness from the sub fuel tank 330.

  Thereafter, or in parallel with the processing of step S303, as described in the second embodiment, among the fuel stored in the main fuel tank 310, the fuel guided to the reformer 320 is reformed. Processing is performed (step S207). The reformed fuel generated in this way is replenished to the sub fuel tank 330 via the sub fuel path 322 (step S208). When the reformed fuel is sufficiently replenished, a normal running state is set (step S209).

  According to the embodiment described above, even if the reformed fuel that should have been subjected to the reforming process returns to heavy fuel due to factors such as change over time, the change is detected again. A modification process is performed. Therefore, it is possible to guarantee the startability at the cold start more reliably. Such follow-up is particularly effective when the control device for the internal combustion engine is mounted on a vehicle with few opportunities for starting the engine 200, such as a plug-in hybrid vehicle.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The control device is also included in the technical scope of the present invention.

It is a typical sectional view of a control device of an internal-combustion engine concerning a 1st embodiment of the present invention. It is a flowchart which shows the reforming process by the control apparatus of the internal combustion engine which concerns on 1st Embodiment. 3 is a flowchart showing a reformed fuel use determination process by the control apparatus for an internal combustion engine according to the first embodiment. It is a flowchart which shows the operation | movement process of the control apparatus of the internal combustion engine which concerns on 2nd Embodiment. It is a flowchart which shows the operation | movement process of the control apparatus of the internal combustion engine which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 200 ... Engine, 100 ... Control apparatus, 201 ... Cylinder, 202 ... Spark plug, 203 ... Piston, 204 ... Connection rod, 205 ... Crankshaft, 206 ... Intake pipe, 207 ... Injector, 208 ... Intake valve, 209 ... Exhaust valve, 210 ... Exhaust pipe, 218 ... Crank position sensor, 219 ... Knock sensor, 220 ... Water temperature sensor, 221 ... Air-fuel ratio sensor, 222 ... Catalyst, 224 ... Filter, 225 ... Main fuel sensor, 226 ... Sub fuel Sensor, 310 ... main fuel tank, 311 ... refueling port, 320 ... reformer, 330 ... sub fuel tank, 341 ... switching valve, 342 ... switching valve

Claims (8)

First storage means for storing fuel for combustion of the internal combustion engine;
Reforming means for generating reformed fuel by subjecting at least a part of the stored fuel to reforming; and
Second storage means for storing the produced reformed fuel;
And a control means for controlling the reforming means so as to selectively perform the reforming process according to the necessity of the reforming process. The control device for an internal combustion engine according to claim 1, wherein the reforming means reduces the degree of heavyness of the at least part of the fuel as the reforming process. It further comprises an exhaust pipe through which the exhaust gas accompanying the combustion passes,
The control device for an internal combustion engine according to claim 1, wherein the reforming unit is in thermal contact with the exhaust pipe. Temperature specifying means for specifying the temperature of the internal combustion engine;
Combustion of the internal combustion engine with at least one of the fuel stored by the first storage means and the reformed fuel stored by the second storage means based on the specified temperature. The control device for an internal combustion engine according to claim 1, further comprising supply means for selectively supplying to the chamber. The supply means supplies the reformed fuel to the combustion chamber when the internal combustion engine is started and the specified temperature falls below a predetermined temperature threshold. The control device for an internal combustion engine according to claim 4. Further comprising a remaining amount specifying means for specifying the remaining amount of the reformed fuel stored in the second storage means,
2. The internal combustion engine according to claim 1, wherein the control unit controls the reforming unit to perform the reforming process when the specified remaining amount falls below a predetermined target storage amount. Control device. A first heavy weight specifying means for specifying a heavy degree of the fuel stored by the first storage means;
The control means controls the reforming means to perform the reforming process when the degree of heavyness of the specified fuel exceeds a predetermined first heavyness degree. Item 7. The control device for an internal combustion engine according to any one of Items 1 to 6. A second heavy weight specifying means for specifying a heavy degree of the reformed fuel stored in the second storage means;
The control means performs the reforming process again to replace the reformed fuel stored in the second storage means when the specified heavy degree exceeds a predetermined second heavy degree. The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the reforming means is controlled as follows.

Images