JP2011169163A - Device for control of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve exhaust emission in a bifuel engine. <P>SOLUTION: A device for control of an internal combustion engine has gas fuel supply units (310, 320, and 330) for supplying gas fuel, and liquid fuel supply units (410, 420, and 430) for supplying liquid fuel. The control device includes: catalyst deterioration degree detectors (124 and 125) for detecting deterioration degree of a catalyst (123) installed on an exhaust route of the internal combustion engine; and a fuel ratio determination unit (100) for determining each supply ratio between the gas fuel supplied by the gas fuel supply unit and the liquid fuel supplied by the liquid fuel supply unit, on the basis of the deterioration degree of the catalyst which is detected by the catalyst deterioration degree detector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of an internal combustion engine control device for an internal combustion engine that is mounted on a vehicle such as an automobile and can selectively use gas fuel and liquid fuel.

  As a control device for this type of internal combustion engine, for example, an apparatus that controls the operation of an internal combustion engine (so-called bi-fuel engine) that uses gas fuel such as CNG (Compressed Natural Gas) and liquid fuel such as gasoline together. is there. In particular, it is known that natural gas fuels have less pollutants in the exhaust discharged after combustion than liquid fuels such as gasoline. For this reason, for example, Patent Document 1 proposes a technique of using GTL (Gas To Liquid), which is a natural gas fuel, as the liquid fuel.

  On the other hand, when two types of fuel having different characteristics are used, it is conceivable to switch the fuel supplied to the internal combustion engine so that an appropriate fuel is used according to the situation. For example, Patent Document 2 proposes a technique of detecting a state of air pollution around the host vehicle and using a fuel in a form that emits less pollutant when it is determined that the pollutant tends to be high in concentration. ing.

JP 2007-239600 A JP 2006-266160 A

  However, even if an attempt is made to prevent air pollution by using the technology according to Patent Document 2 described above, an appropriate effect cannot be obtained if the purification performance of the vehicle itself is degraded. Specifically, when the catalyst provided for purifying exhaust gas deteriorates and cannot fully perform its original purification function, no matter what fuel is used, there are many pollutants. It will be discharged. In this way, even if the emission of pollutants is reduced in accordance with the environmental conditions around the vehicle, if the exhaust gas purification performance of the vehicle itself is significantly degraded, the air will be contaminated as a result. Will end up. Therefore, the above-described technique has a technical problem that there is a possibility that air pollution cannot be reliably prevented.

  The present invention has been made in view of the above-described problems, for example, and an object of the present invention is to provide a control device for an internal combustion engine that can improve exhaust emission appropriately in a bi-fuel engine.

  In order to solve the above-mentioned problems, the control apparatus for an internal combustion engine of the present invention is a control apparatus for an internal combustion engine having gas fuel supply means for supplying gas fuel and liquid fuel supply means for supplying liquid fuel, the internal combustion engine Catalyst deterioration degree detection means for detecting the deterioration degree of the catalyst provided in the exhaust path of the gas, and the gas fuel supplied by the gas fuel supply means based on the catalyst deterioration degree detected by the catalyst deterioration degree detection means And a fuel ratio determining means for determining a supply ratio of the liquid fuel supplied by the liquid fuel supply means.

  The control device for an internal combustion engine of the present invention is mounted on a vehicle such as an automobile, and controls the operation of the internal combustion engine that is operated by selectively using gas fuel such as natural gas and liquid fuel such as gasoline. The gas fuel is supplied to the internal combustion engine by the gas fuel supply means. On the other hand, the liquid fuel is supplied to the internal combustion engine by the liquid fuel supply means. The supply amounts of the gas fuel and the liquid fuel are adjusted, for example, by adjusting valves provided in the gas fuel supply means and the liquid fuel supply means. As a result, in the internal combustion engine, operation with gas fuel, operation with liquid fuel, and further operation with both gas fuel and liquid fuel can be realized.

  According to the control apparatus for an internal combustion engine of the present invention, the degree of deterioration of the catalyst provided in the exhaust path of the internal combustion engine is detected by the catalyst temperature detection means during operation of the internal combustion engine. The “degradation degree of the catalyst” here is a parameter indicating how much the purification function of the catalyst has deteriorated, and the catalyst deterioration degree detection means is based on, for example, a gas component passing through the catalyst. Detect the degree of catalyst degradation.

  When the deterioration degree of the catalyst is detected, the supply ratios of the gas fuel supplied by the gas fuel supply means and the liquid fuel supplied by the liquid fuel supply means are respectively determined based on the detected deterioration degree of the catalyst. . That is, in an internal combustion engine, whether to operate only with gas fuel, operate only with liquid fuel, or operate with both gas fuel and liquid fuel, in which case the supply ratio of gas fuel and liquid fuel Is determined.

  Here, the operation with gas fuel is less burdened on the catalyst than the operation with liquid fuel. For example, even if the catalyst is deteriorated and the operation with liquid fuel cannot sufficiently purify the exhaust gas, In operation with fuel, even a deteriorated catalyst may be sufficient to purify exhaust. Further, the operation with gas fuel has a characteristic that the catalyst purification reaction heat is less likely to be generated than the operation with liquid fuel, and therefore, an increase in the catalyst temperature can be suppressed. That is, deterioration of the catalyst can be suppressed. Therefore, if the supply ratio of the gas fuel and the liquid fuel is determined based on the degree of deterioration of the catalyst, the purification function of the catalyst can be exhibited more efficiently.

  It should be noted that the value for determining the supply ratio of gas fuel and liquid fuel under what circumstances is determined in advance theoretically, experimentally, or empirically, and is stored in a storage medium or the like included in the fuel ratio determining means. Has been. Or you may comprise so that it may calculate in real time using the deterioration degree of a catalyst, another parameter, etc.

  As described above, according to the control apparatus for an internal combustion engine of the present invention, exhaust emission can be improved extremely suitably by efficiently exhibiting the purification function of the catalyst.

  In one aspect of the control apparatus for an internal combustion engine of the present invention, the catalyst deterioration degree detection means includes an air-fuel ratio detection means provided upstream of the catalyst, and an oxygen amount detection means provided downstream of the catalyst. .

  According to this aspect, the catalyst deterioration degree detecting means detects the air-fuel ratio (that is, the ratio of fuel and air in the air-fuel mixture) upstream of the catalyst, and the exhaust gas that has passed through the catalyst downstream of the catalyst. An oxygen amount detecting means for detecting the amount of oxygen is detected, and the degree of deterioration of the catalyst is determined based on the detected air-fuel ratio and the amount of oxygen. Specifically, for example, the oxygen storage amount of the catalyst is calculated from the oxygen amount when the air-fuel ratio is rich and when the air-fuel ratio is lean, and the degree of deterioration of the catalyst is determined based on the oxygen storage amount. In this case, the smaller the oxygen storage amount, the more the catalyst is degraded.

  In this aspect, since the two parameters of the air-fuel ratio and the oxygen amount described above may be used, the degree of deterioration of the catalyst can be detected relatively easily and reliably. Therefore, it is possible to more suitably determine the fuel supply ratio and improve exhaust emission.

  In another aspect of the control apparatus for an internal combustion engine of the present invention, the fuel ratio determination means increases the supply ratio of the gas fuel by the gas fuel supply means as the degree of deterioration of the catalyst increases.

  According to this aspect, for example, when the degree of deterioration of the catalyst is large and the purification function is remarkably reduced, the supply ratio of the gas fuel is increased (that is, the supply ratio of the liquid fuel is decreased), and the burden on the catalyst is increased. And the deterioration of the catalyst is suppressed. On the other hand, when the degree of deterioration of the catalyst is small and a sufficient purification function is maintained, the gas fuel supply ratio is reduced (that is, the liquid fuel supply ratio is increased).

  In this aspect, as described above, the fuel is supplied at an appropriate rate according to the degree of deterioration of the catalyst. That is, the fuel corresponding to the current purification function of the catalyst is selected. Therefore, exhaust emission can be improved extremely efficiently.

  In another aspect of the control device for an internal combustion engine according to the present invention, the fuel ratio determining means is configured such that when the internal combustion engine is in a high load operation, the gas is determined in the gas ratio as compared with a case where the internal combustion engine is in a low load operation. The supply ratio of the gas fuel by the fuel supply means is increased.

  According to this aspect, for example, when the internal combustion engine is in a high load operation due to acceleration of a vehicle on which the internal combustion engine is mounted, the gas fuel is reduced as compared with the case of the low load operation (or steady operation). Supply ratio is increased. In other words, when the low load operation is performed, the gas fuel supply ratio is reduced as compared with the case where the high load operation is performed.

  Here, particularly when the internal combustion engine is operating at a high load, it is difficult to maintain the purification function of the catalyst. Therefore, as described above, the purification function of the catalyst can be stabilized by increasing the supply ratio of the gas fuel that imposes a small burden on the catalyst during high load operation. Moreover, since the supply ratio of gas fuel is reduced during low-load operation, it is possible to prevent the usage amount of gas fuel and liquid fuel from being biased to one side.

  In another aspect of the control device for an internal combustion engine of the present invention, a shift means for switching a gear ratio, a gas fuel remaining amount detecting means for detecting the remaining amount of the gas fuel, and the remaining amount of the gas fuel are below a predetermined threshold value. In this case, there is further provided a shift switching means for switching a shift pattern in the shift means so that the rotational speed of the internal combustion engine is not easily increased.

  According to this aspect, for example, when the remaining amount of the gas fuel in the gas fuel tank or the like is detected and the remaining amount falls below a predetermined threshold value, the speed change means is configured to prevent the internal combustion engine from increasing in speed. The shift pattern is switched. That is, in the case of an automatic transmission vehicle or the like, when the remaining amount of gas is decreasing, the shift pattern that is normally used is switched to a shift pattern that is different from the normal shift pattern for realizing low engine rotation. The “predetermined threshold value” in this aspect is a threshold value for determining whether or not the gas fuel has been reduced to such an extent that inconvenience will occur in the future operation with the gas fuel. Or it is sought and set empirically.

  By switching the shift pattern as described above, the internal combustion engine can be rotated at a low speed, and the consumption amount of gas fuel can be reduced. Therefore, for example, in the case where the supply ratio of the gas fuel is increased based on the degree of deterioration of the catalyst, and as a result, the consumption amount of the gas fuel is increased, the gas fuel is prevented from being wasted. be able to. Accordingly, it is possible to continue the operation with the gas fuel for a longer time.

  Since the place where gas fuel can be replenished is limited compared with liquid fuel, the effect of this aspect of reducing consumption of gas fuel is extremely useful.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

It is a schematic diagram showing the whole composition of an engine system. It is a flowchart which shows each process of the fuel switching control by the control apparatus of an internal combustion engine. It is a conceptual diagram which shows an example of the detection method of a catalyst deterioration degree. It is a graph which shows the relationship between oxygen storage amount and a catalyst deterioration degree. It is a graph which shows the supply ratio of the liquid fuel and gas fuel with respect to a catalyst degradation degree. It is a flowchart which shows each process of the shift pattern switching control by the control apparatus of an internal combustion engine. FIG. 6 is an upshift diagram showing a shift pattern before and after switching control. It is a downshift diagram which shows the shift pattern before switching control and after control.

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

  First, the configuration of the entire engine system to which the control device for an internal combustion engine according to the present embodiment is applied will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of the engine system. In FIG. 1, for convenience of explanation, among the elements constituting the engine system, only those closely related to the present embodiment are selectively illustrated, and the other elements are omitted as appropriate.

  In FIG. 1, the engine system according to the present embodiment includes an ECU (Engine Control Unit) 100, a compressor 110, a turbine 120, and an engine 200.

  The ECU 100 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls the entire operation of the engine system. The main part of the control device for an internal combustion engine according to the present embodiment is configured as the ECU 100.

  The compressor 110 compresses the air that has flowed in and supplies the compressed air downstream. The turbine 120 rotates using the exhaust supplied from the engine 200 as power. The turbine 120 is connected to the compressor 110 via a shaft, and is configured to be able to rotate integrally with each other. That is, the turbine 120 and the compressor 110 constitute a turbocharger.

  The engine 200 is a bi-fuel engine that is a power source of a vehicle such as an automobile, and an in-line four-cylinder engine in which four cylinders 201 are arranged in series in a cylinder block is taken as an example. A gas fuel such as natural gas is supplied to the engine 200 from the gas fuel tank 310 via the gas fuel supply pipe 320. The engine 200 is supplied with liquid fuel such as gasoline or alcohol fuel from the liquid fuel tank 410 via the liquid fuel supply pipe 420.

  The gas fuel supply pipe 320 and the liquid fuel supply pipe 420 are provided with adjustment valves 330 and 430, respectively, and the amount of fuel supply can be adjusted by changing the opening degree. The opening degree of the adjustment valves 330 and 430 is controlled by the ECU 100. The ECU 100 determines the supply ratio of gas fuel and liquid fuel so that, for example, the fuel consumption efficiency is optimal during normal operation. In particular, the control device for an internal combustion engine according to the present embodiment improves exhaust emission. Therefore, fuel supply control different from normal is performed under predetermined conditions. A specific control method will be described in detail later.

  In the combustion chamber in the cylinder 201 of the engine 200, an air-fuel mixture obtained by mixing air supplied through the intake pipe and fuel injected and supplied from an injector or the like in the intake port communicating with the intake pipe is sucked. The Although not shown in detail here, the engine 200 performs the reciprocating motion of the piston that occurs when the air-fuel mixture burns inside each cylinder 201 via the connecting rod. It can be converted into a rotational motion. The engine speed of the engine 200 can be detected by an engine speed sensor 205.

  An air flow meter 102, an air cleaner 103, and an intake pressure sensor 105 are provided upstream from the compressor 110.

  The air flow meter 102 is configured to be able to detect the amount of air passing through (in other words, air sucked from the outside).

  The air cleaner 103 is provided downstream of the air flow meter 102, purifies air sucked from the outside, and supplies it to the compressor 110.

  The intake sensor 105 is configured to be able to detect the intake pressure near the inlet of the compressor 110.

  An intercooler 113 and a throttle valve 114 are provided on the downstream side of the compressor 110.

  The intercooler 113 is configured to be able to cool intake air and increase the supercharging efficiency of the air.

  The throttle valve 114 is an electronically controlled valve, and is configured such that its opening / closing operation is controlled by a throttle valve motor (not shown).

  The air-fuel mixture introduced into the cylinder 201 from the intake side is ignited by an ignition operation by an ignition device (not shown), and an explosion process is performed in the cylinder 201. When the explosion process is performed, the burned air-fuel mixture (including a partially unburned air-fuel mixture) is guided to the exhaust pipe in the exhaust process following the explosion process.

  A three-way catalyst 123, an air-fuel ratio sensor 124, and an oxygen sensor 125 are provided on the downstream side of the turbine 120.

The three-way catalyst 123 is an example of the “catalyst” of the present invention, and purifies HC (hydrocarbon), CO ₂ (carbon dioxide), and NOx (nitrogen oxide) contained in the exhaust gas that has passed through the turbine 120. . A plurality of the three-way catalysts 123 may be provided on the exhaust pipe.

  The air-fuel ratio sensor 124 is an example of the “air-fuel ratio detection means” of the present invention, and is configured to be able to detect the air-fuel ratio upstream of the three-way catalyst 123. The air-fuel ratio detected here is output to ECU 100.

  The oxygen sensor 124 is an example of the “oxygen amount detection means” of the present invention, and is configured to detect the oxygen amount downstream of the three-way catalyst 123. The amount of oxygen detected here is output to ECU 100.

  Next, fuel switching control by the control device for an internal combustion engine according to the present embodiment will be described with reference to FIGS. 2 to 5 in addition to FIG. FIG. 2 is a flowchart showing each step of the fuel switching control by the control device for the internal combustion engine, and FIG. 3 is a conceptual diagram showing an example of a method for detecting the degree of catalyst deterioration. FIG. 4 is a graph showing the relationship between the oxygen storage amount and the degree of catalyst deterioration, and FIG. 5 is a graph showing the supply ratio of liquid fuel and gas fuel to the degree of catalyst deterioration.

  In FIG. 2, the internal combustion engine control apparatus according to the present embodiment first detects the load of the engine 200 when the engine 200 is operating (step S01). The load of the engine 200 is detected based on, for example, the temperature of cooling water (not shown), the integrated air amount detected by the air flow meter 102, the intake pressure detected by the intake pressure sensor 105, and the like.

  Subsequently, the control device for the internal combustion engine according to the present embodiment detects the degree of deterioration of the three-way catalyst 123 (step S02). The degree of deterioration of the three-way catalyst 123 is detected by an air-fuel ratio sensor 124 provided upstream of the three-way catalyst 123 and an oxygen sensor 125 provided downstream. Below, the specific detection method of a catalyst deterioration degree is demonstrated.

  In FIG. 3, when detecting the degree of deterioration of the three-way catalyst 123, first, the air-fuel ratio upstream of the three-way catalyst 123 is controlled to be alternately rich or lean. Then, the oxygen storage amount of the three-way catalyst 123 is detected based on the oxygen amount detected by the oxygen sensor 125 when the sky ratio is switched between rich and lean. More specifically, the maximum oxygen storage amount Cmax is detected.

  In FIG. 4, the maximum oxygen storage amount Cmax and the degree of deterioration of the three-way catalyst 123 have a relationship as shown in the figure. That is, the smaller the maximum oxygen storage amount Cmax is, the more the catalyst is deteriorated.

  Returning to FIG. 2, when the degree of deterioration of the three-way catalyst 123 is detected, the ECU 100 determines an optimum fuel ratio according to the degree of deterioration (step S03). That is, the ratio of the gas fuel to be supplied via the gas fuel supply pipe 320 and the liquid fuel to be supplied via the liquid fuel supply pipe 420 is determined.

  Here, the operation with gas fuel is less burdened on the three-way catalyst 123 than the operation with liquid fuel. For example, when the three-way catalyst 123 is deteriorated and the operation with liquid fuel cannot exhaust the exhaust gas sufficiently. Even so, in the operation with gas fuel, even the three-way catalyst 123 that has deteriorated may be sufficiently purified. Further, the operation with gas fuel has a characteristic that the temperature of the three-way catalyst 123 can be suppressed because the heat of the catalyst purification reaction is less likely to be generated than the operation with liquid fuel. That is, deterioration of the three-way catalyst 123 can be suppressed.

  In FIG. 5, the ratio of the gas fuel and the liquid fuel is determined so that the ratio of the gas fuel increases as the degree of deterioration of the three-way catalyst 123 increases. Specifically, when the degree of deterioration of the three-way catalyst 123 is relatively large and the purification function cannot be sufficiently exerted, the ratio of the gas fuel with a small burden on the three-way catalyst 123 is increased. On the other hand, when the degree of deterioration of the three-way catalyst 123 is relatively small and the purification function can be sufficiently exhibited, the ratio of the liquid fuel is increased. Thus, if the supply ratio of the gas fuel and the liquid fuel is determined based on the degree of deterioration of the three-way catalyst 123, the purification function of the three-way catalyst 123 can be exhibited more efficiently.

  Returning to FIG. 2 again, when the optimum fuel ratio is determined, it is determined whether or not the engine 200 is operating at a high load (step S04). Specifically, it is determined whether engine 200 is operating at a high load based on the load of engine 100 detected in step S01 or by detecting the vehicle speed.

  Here, when it is determined that the engine 200 is operating at a high load (step S04: YES), the gas fuel and the liquid fuel are supplied at the optimum fuel ratio determined in step S03 (step S05). Specifically, the opening degree of the adjustment valve 330 provided in the gas fuel supply pipe 320 and the adjustment valve 430 provided in the liquid fuel supply pipe 420 are respectively adjusted by the ECU 100.

  It is said that it is difficult to maintain the purification function of the three-way catalyst 123 when the engine 200 is operating at a high load. Therefore, if the fuel is supplied at the optimum fuel ratio, the purification function of the three-way catalyst 123 can be stabilized.

  On the other hand, when it is determined that the engine 200 is not operating at a high load (step S04: NO), an operation using liquid fuel is performed (step S06). Specifically, the ECU 100 closes the adjustment valve 330 provided in the gas fuel supply pipe 320 and operates the engine 200 using only liquid fuel.

  When the engine 200 is not in a high load operation (in other words, in a low load operation), it is said that it is relatively easy to maintain the purification function of the three-way catalyst 123. Therefore, if the liquid fuel is used when it is not in a high load operation, it is possible to prevent the usage amount of the gas fuel and the liquid fuel from being biased to one side.

  As described above, in the fuel switching control by the control device for an internal combustion engine according to the present embodiment, fuel is supplied based on the degree of deterioration of the three-way catalyst 123 so that the purification function can be sufficiently exerted. The Therefore, exhaust emission can be improved.

  Next, shift pattern switching control by the control device for an internal combustion engine according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing each step of the shift pattern switching control by the control device for the internal combustion engine. FIG. 7 is an upshift diagram showing a shift pattern before and after switching control, and FIG. 8 is a downshift diagram showing a shift pattern before and after switching control.

  The control apparatus for an internal combustion engine according to the present embodiment can also perform shift pattern switching control in parallel with the fuel switching control of the engine 200 described above.

  6, the control apparatus for an internal combustion engine according to the present embodiment first detects the remaining amount of the gas fuel by the remaining amount sensor 315 provided in the gas fuel tank 310 (step S11). The detected remaining amount of gas fuel is transmitted to the ECU 100, and it is determined whether or not it is below a predetermined threshold (step S12). Note that the predetermined threshold value is set in advance to determine whether or not the gas fuel has been reduced to such an extent that inconvenience will occur in the future operation with the gas fuel.

  Here, when the remaining amount of gas fuel is equal to or less than the predetermined threshold (step S12: YES), the shift pattern is switched to a pattern different from the normal (step S14). Specifically, the shift pattern (Base) indicated by the solid line in FIGS. 7 and 8 is switched to the shift pattern indicated by the broken line. That is, the shift pattern is changed so that the rotation speed of the engine 200 does not easily become high.

  By switching the shift pattern as described above, it is possible to reduce the rotation speed of the engine 200 and to reduce the fuel consumption. Therefore, for example, when the supply ratio of the gas fuel is increased based on the degree of deterioration of the three-way catalyst 123, and as a result, the consumption amount of the gas fuel is increased, the gas fuel is wasted. Can be prevented. Accordingly, it is possible to continue the operation with the gas fuel for a longer time.

  If the remaining amount of gas fuel is not less than or equal to the predetermined threshold value (step S12: NO), the shift pattern remains the normal pattern (step S14).

  As described above, in the shift pattern switching control by the control device for an internal combustion engine according to the present embodiment, even when the consumption of gas fuel is remarkably increased by the fuel switching control described above, It is possible to continue operation with gas fuel for a long time. Therefore, the effect of improving the exhaust emission can be surely exhibited.

  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.

  DESCRIPTION OF SYMBOLS 100 ... ECU, 102 ... Air flow meter, 103 ... Air cleaner, 105 ... Intake pressure sensor, 110 ... Turbine, 113 ... Intercooler, 114 ... Throttle valve, 115 ... Throttle opening sensor, 120 ... Turbine, 123 ... Three-way catalyst, 124 ... Air-fuel ratio sensor, 125 ... Oxygen sensor, 200 ... Engine, 201 ... Cylinder, 310 ... Gas fuel tank, 315 ... Remaining amount sensor, 320 ... Gas fuel supply pipe, 330 ... Adjustment valve, 410 ... Liquid fuel tank, 420 ... Liquid fuel supply pipe, 430 ... Adjustment valve

Claims (5)

A control device for an internal combustion engine having a gas fuel supply means for supplying gas fuel and a liquid fuel supply means for supplying liquid fuel,
Catalyst deterioration degree detecting means for detecting the degree of deterioration of the catalyst provided in the exhaust path of the internal combustion engine;
A fuel ratio for determining the supply ratio of the gas fuel supplied by the gas fuel supply means and the liquid fuel supplied by the liquid fuel supply means based on the deterioration degree of the catalyst detected by the catalyst deterioration degree detection means. A control device for an internal combustion engine, comprising: a determination unit. The catalyst deterioration degree detecting means includes
Air-fuel ratio detection means provided upstream of the catalyst;
The control apparatus for an internal combustion engine according to claim 1, further comprising: an oxygen amount detection unit provided downstream of the catalyst.   3. The control device for an internal combustion engine according to claim 1, wherein the fuel ratio determination unit increases the supply ratio of the gas fuel by the gas fuel supply unit as the degree of deterioration of the catalyst increases.   The fuel ratio determination means increases the supply ratio of the gas fuel by the gas fuel supply means when the internal combustion engine is in a high load operation, compared to when the internal combustion engine is in a low load operation. The control device for an internal combustion engine according to any one of claims 1 to 3. Transmission means for switching the transmission ratio;
Gas fuel remaining amount detecting means for detecting the remaining amount of the gas fuel;
Shift change means for changing a shift pattern in the shift means so that the rotational speed of the internal combustion engine is unlikely to increase when the remaining amount of the gas fuel becomes a predetermined threshold value or less. The control device for an internal combustion engine according to any one of claims 1 to 4.

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