JP2009275568A - Variable compression ratio internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique preventing the occurrence of knocking in an internal combustion engine by suppressing an excessive increase in the compression ratio of the internal combustion engine with respect to alcohol concentration in fuel when an alcohol concentration detection means fails in a variable compression ratio internal combustion engine. <P>SOLUTION: This variable compression ratio internal combustion engine includes an alcohol concentration sensor detecting the alcohol concentration in fuel with alcohol contained in gasoline, and a compression ratio variable mechanism changing the compression ratio of the internal combustion engine. The compression ratio processing of the internal combustion engine using the compression ratio variable mechanism is changed according to the alcohol concentration detected by the alcohol concentration sensor. When the failure of the alcohol concentration sensor is detected (Yes in S101), the compression ratio processing of the internal combustion engine is set to compression ratio processing when only gasoline is used as fuel (S102 to S104). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable compression ratio internal combustion engine.

A variable compression ratio internal combustion engine that includes an alcohol concentration sensor that detects an alcohol concentration in fuel supplied to the internal combustion engine, and that optimally sets the compression ratio of the internal combustion engine according to the alcohol concentration detected by the alcohol concentration sensor Is disclosed (for example, see Patent Document 1).
JP-A 63-289234 JP-A-5-71400 Japanese Patent Laid-Open No. 62-101849 Japanese Utility Model Publication No. 2-56835

  Incidentally, an alcohol concentration sensor that detects the alcohol concentration in the fuel may fail. When the alcohol concentration sensor fails, the compression ratio of the internal combustion engine cannot be changed according to the alcohol concentration in the fuel. Then, for example, the compression ratio of the internal combustion engine becomes excessively high with respect to the alcohol concentration in the fuel, and knocking may occur in the internal combustion engine.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to compress the internal combustion engine with respect to the alcohol concentration in the fuel when the alcohol concentration detection means fails in the variable compression ratio internal combustion engine. An object of the present invention is to provide a technique for suppressing an excessive increase in the ratio and preventing the occurrence of knocking in the internal combustion engine.

In the present invention, the following configuration is adopted. That is, the present invention
Alcohol concentration detection means for detecting the alcohol concentration in fuel containing alcohol in gasoline;
A variable compression ratio mechanism for changing the compression ratio of the internal combustion engine;
With
In the variable compression ratio internal combustion engine that changes the compression ratio processing of the internal combustion engine using the compression ratio variable mechanism according to the alcohol concentration detected by the alcohol concentration detection means,
Failure detection means for detecting a failure of the alcohol concentration detection means;
When the failure detection means detects a failure of the alcohol concentration detection means, the compression ratio process setting means at the time of setting the compression ratio process of the internal combustion engine to the compression ratio process when using only gasoline as fuel,
Is a variable compression ratio internal combustion engine.

  The alcohol concentration detection means for detecting the alcohol concentration in the fuel containing alcohol in gasoline may fail. If the alcohol concentration detection means fails, the compression ratio of the internal combustion engine cannot be changed according to the alcohol concentration in the fuel. Then, for example, the compression ratio of the internal combustion engine becomes excessively high with respect to the alcohol concentration in the fuel, and knocking may occur in the internal combustion engine.

  Therefore, in the present invention, when a failure of the alcohol concentration detection means is detected, the compression ratio processing of the internal combustion engine is set to the compression ratio processing when only gasoline is used as fuel.

  According to the present invention, when a failure of the alcohol concentration detection means is detected, the compression ratio process of the internal combustion engine is set to the compression ratio process when only gasoline is used as fuel. Here, the compression ratio process when only gasoline is used as the fuel is a compression ratio process in which the highest compression ratio side is not used compared to the compression ratio process when alcohol is contained in the fuel. As described above, when the failure of the alcohol concentration detecting means is detected, the compression ratio processing in the lowest region is set. According to this, since the compression ratio process in the lowest region is performed regardless of the alcohol concentration in the fuel, the compression ratio of the internal combustion engine does not become excessively high with respect to the alcohol concentration in the fuel. Therefore, knocking of the internal combustion engine that occurs due to an excessively high compression ratio of the internal combustion engine with respect to the alcohol concentration in the fuel can be prevented.

  The compression ratio variable mechanism may be configured to displace the cylinder block relative to the crankcase.

  According to the present invention, the compression ratio of the internal combustion engine can be changed by relatively displacing the cylinder block with respect to the crankcase.

  A knocking detecting means for detecting knocking occurring in the internal combustion engine; and the failure compression ratio processing setting means, when the failure detecting means detects a failure of the alcohol concentration detecting means, the alcohol concentration detecting means When the compression ratio processing of the internal combustion engine is changed according to the alcohol concentration detected before the failure is detected, and the knocking detection means detects knocking thereafter, the compression ratio processing of the internal combustion engine is performed when only gasoline is used as fuel. It is better to set the compression ratio processing.

  According to the present invention, when a failure of the alcohol concentration detection means is detected, the compression ratio processing of the internal combustion engine is changed according to the alcohol concentration detected by the alcohol concentration detection means before the failure detection, and the compression ratio processing is optimized. Can be planned. Thereby, it can suppress that the compression ratio of an internal combustion engine becomes low too much, and can improve a fuel consumption and power performance more. However, when the knocking detection means detects knocking after that, the compression ratio processing of the internal combustion engine is set to the compression ratio processing when only gasoline is used as the fuel, and the compression in the lowest region is set regardless of the alcohol concentration contained in the fuel. Perform ratio processing. Thereby, knocking of the internal combustion engine can be prevented.

  The failure compression ratio processing setting means uses the compression ratio of the internal combustion engine and only gasoline as the fuel when the compression ratio processing of the internal combustion engine is set to the compression ratio processing when only gasoline is used as fuel. It is good to fix to the compression ratio used in the compression ratio process at the time.

  According to the present invention, when a failure of the alcohol concentration detection means is detected, the compression ratio of the internal combustion engine is fixed to the compression ratio used in the compression ratio processing when only gasoline is used as fuel. Here, the compression ratio process when only gasoline is used as the fuel is a compression ratio process in which the highest compression ratio side is not used compared to the compression ratio process when alcohol is contained in the fuel. The compression ratio used in the compression ratio process when only gasoline is used as the fuel is a low compression ratio among the compression ratios that the internal combustion engine can take in the operating state. As described above, when the failure of the alcohol concentration detecting means is detected, the internal combustion engine is operated with the compression ratio fixed to a low value. According to this, the compression ratio of the internal combustion engine does not become excessively high with respect to the alcohol concentration in the fuel because the compression ratio is fixed regardless of the alcohol concentration in the fuel. Therefore, knocking of the internal combustion engine that occurs due to an excessively high compression ratio of the internal combustion engine with respect to the alcohol concentration in the fuel can be prevented.

According to the present invention, in the variable compression ratio internal combustion engine, when the alcohol concentration detecting means fails, it is possible to prevent the compression ratio of the internal combustion engine from becoming excessively high with respect to the alcohol concentration in the fuel. It can be prevented from occurring.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which a variable compression ratio internal combustion engine according to the present embodiment is applied. The internal combustion engine 1 shown in FIG. 1 is a four-stroke cycle gasoline engine having four cylinders 2. The internal combustion engine 1 is mounted on a vehicle. An intake pipe 5 is connected to a combustion chamber in the cylinder 2 of the internal combustion engine 1 via an intake port 4 provided in the cylinder head 3. Inflow of intake air from the intake port 4 to the combustion chamber in the cylinder 2 is controlled by an intake valve 6. An exhaust pipe 8 is connected to the combustion chamber in the cylinder 2 via an exhaust port 7 provided in the cylinder head 3. Exhaust gas discharge from the combustion chamber in the cylinder 2 to the exhaust port 7 outside the cylinder 2 is controlled by an exhaust valve 9.

  A fuel injection valve 10 is disposed in the intake port 4. Fuel is supplied from a fuel tank 12 to the fuel injection valve 10 through a fuel supply pipe 11. The fuel supplied to the internal combustion engine 1 in the present embodiment contains alcohol in gasoline. In the middle of the fuel supply pipe 11, an alcohol concentration sensor 13 is disposed. The alcohol concentration sensor 13 detects the alcohol concentration in the fuel. The alcohol concentration sensor 13 corresponds to the alcohol concentration detection means of the present invention.

  A spark plug 14 is disposed at the top of the cylinder 2. The spark plug 14 ignites an air-fuel mixture in which fuel and air in the combustion chamber in the cylinder 2 are mixed.

  A piston 17 connected to the crankshaft 15 of the internal combustion engine 1 via a connecting rod 16 reciprocates in the cylinder 2.

  Here, in the internal combustion engine 1, the compression ratio of the internal combustion engine 1 is changed by moving the cylinder block 19 relative to the crankcase 20 in the axial direction of the cylinder 2 by the compression ratio variable mechanism 18. . In other words, the variable compression ratio mechanism 18 moves the cylinder head 3 together with the cylinder block 19 relative to the crankcase 20 in the axial direction of the cylinder 2, thereby combusting the cylinder block 19, the cylinder head 3 and the piston 17. The volume of the chamber is changed, and as a result, the compression ratio of the internal combustion engine 1 is changed. For example, when the cylinder block 19 is relatively moved away from the crankcase 20, the combustion chamber volume increases and the compression ratio decreases. When the cylinder block 19 is relatively moved in the direction approaching the crankcase 20, the combustion chamber volume is reduced and the compression ratio is increased.

  The compression ratio variable mechanism 18 includes a shaft portion 18a, a cam portion 18b having a circular cam profile fixed to the shaft portion 18a while being eccentric with respect to the central axis of the shaft portion 18a, and the cam portion 18b. A movable bearing portion 18c which has an outer shape and is rotatable with respect to the shaft portion 18a and attached in an eccentric state like the cam portion 18b, a worm wheel 18d provided concentrically with the shaft portion 18a, and a worm wheel 18d And a motor 18f that rotationally drives the worm 18e. The cam portion 18 b is installed in a storage hole provided in the cylinder block 19, the movable bearing portion 18 c is installed in a storage hole provided in the crankcase 20, and the motor 18 f is fixed to the cylinder block 19. And moves integrally with the cylinder block 19. Here, the driving force from the motor 18f is transmitted to the shaft portion 18a via the worm 18e and the worm wheel 18d. Then, the cam block 18b and the movable bearing portion 18c in an eccentric state are driven, whereby the cylinder block 19 is moved relative to the crankcase 20 in the axial direction of the cylinder 2.

  The internal combustion engine 1 configured as described above is provided with an ECU 21 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 21 is a unit that controls the operating state of the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the driver's request.

  Various sensors such as an alcohol concentration sensor 13, a crank position sensor 22, and an accelerator position sensor 23 are connected to the ECU 21 through electric wiring, and output signals from these various sensors are input to the ECU 21. On the other hand, the fuel injection valve 10, the spark plug 14, and the motor 18f are connected to the ECU 21 via electric wiring, and these devices are controlled by the ECU 21.

  The internal combustion engine 1 in the present embodiment performs a compression ratio process for changing the compression ratio of the internal combustion engine 1 according to the alcohol concentration in the fuel and the operating state of the internal combustion engine 1. The compression ratio process of the internal combustion engine 1 in the present embodiment will be described below.

  First, the compression ratio process that is changed according to the operating state of the internal combustion engine 1 will be described. FIG. 2 is a schematic view illustrating the compression ratio according to the operating state of the internal combustion engine 1 in the present embodiment. 2 represents the engine speed of the internal combustion engine 1, and the vertical axis represents the engine load of the internal combustion engine 1. The engine speed of the internal combustion engine 1 is obtained from the output value of the crank position sensor 22, and the engine load of the internal combustion engine 1 is obtained from the output value of the accelerator position sensor 23.

  In FIG. 2, when the operating state of the internal combustion engine 1 is a low load, the compression ratio of the internal combustion engine 1 is set to a high compression ratio. On the other hand, when the operating state of the internal combustion engine 1 is high, the compression ratio of the internal combustion engine 1 is set to a low compression ratio. Thus, by performing the compression ratio process for changing the compression ratio according to the operating state of the internal combustion engine 1, the fuel efficiency and the power performance are improved.

  Next, the compression ratio process that is changed according to the alcohol concentration in the fuel will be described. FIG. 3 is a schematic view illustrating compression ratios that can be selected according to the alcohol concentration in the fuel in this embodiment. The horizontal axis of FIG. 3 represents the alcohol concentration in the fuel, the vertical axis represents the compression ratio of the internal combustion engine 1, and the hatched area in the figure represents the compression ratio that can be selected by the internal combustion engine 1. The alcohol concentration in the fuel is obtained from the output value of the alcohol concentration sensor 13.

  In FIG. 3, when the alcohol concentration in the fuel is low, the compression ratio only on the low compression ratio side can be selected and the selection range is narrow. On the other hand, when the alcohol concentration in the fuel is high, the compression ratio on the high compression ratio side can be selected, and the selection range is expanded.

  Thus, the compression ratio of the internal combustion engine 1 is changed not only according to the operating state of the internal combustion engine 1 but also according to the alcohol concentration in the fuel. For this reason, for example, when the alcohol concentration in the fuel is 0% (fuel only from gasoline) or the alcohol concentration in the fuel is 100% (fuel only from alcohol), the compression ratio depends on the alcohol concentration in the fuel. A plurality of processing maps are obtained in advance by experiments or the like, and the ECU 21 stores them. Each of these maps can determine the compression ratio according to the operating state of the internal combustion engine 1.

  Here, for example, a map when the alcohol concentration in the fuel is 0% is shown in FIG. 4, and a map when the alcohol concentration in the fuel is 100% is shown in FIG. In the map of FIG. 4, the selectable compression ratio is 8 to 12, the selectable compression ratio is small, and the selection range is narrow. On the other hand, in the map of FIG. 5, the selectable compression ratio is 8 to 15, the selectable compression ratio is large, and the selection range is wide. This is because, when the alcohol concentration in the fuel is 0%, if the proportion of gasoline in the fuel is large, knocking occurs at a high compression ratio, so the selectable compression ratio is limited to the low compression ratio. It is.

  One map is selected according to the alcohol concentration in the fuel from a plurality of maps divided according to the alcohol concentration as shown in FIG. 4 and FIG. 5, and according to the operating state of the internal combustion engine 1 based on the selected map. The compression ratio of the internal combustion engine 1 is changed and compression ratio processing is performed.

  Incidentally, the alcohol concentration in the fuel is detected by the alcohol concentration sensor 13, but the alcohol concentration sensor 13 may fail.

  If the alcohol concentration sensor 13 fails, there is a problem that one map cannot be selected according to the alcohol concentration in the fuel, and the compression ratio of the internal combustion engine 1 cannot be changed according to the alcohol concentration in the fuel. Then, for example, the compression ratio of the internal combustion engine 1 becomes excessively high with respect to the alcohol concentration in the fuel, and knocking may occur in the internal combustion engine 1.

  Therefore, in this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process of the internal combustion engine 1 is set to a compression ratio process when the alcohol concentration in the fuel is 0%, that is, only gasoline is used as the fuel. I tried to do it.

  According to the present embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process of the internal combustion engine 1 is set to the compression ratio process when only gasoline is used as fuel. Specifically, in this embodiment, the map in FIG. 4 when the alcohol concentration in the fuel is 0% is forcibly selected. Then, a compression ratio process is performed for changing the compression ratio according to the operation state of the internal combustion engine 1 based on the map of FIG.

  Here, the compression ratio process when the alcohol concentration in the fuel is 0%, that is, when only gasoline is used as the fuel, is to use the map of FIG. 4, compared with the compression ratio process when the alcohol is contained in the fuel. Thus, the compression ratio processing is performed on the low compression ratio side where the highest compression ratio side is not used. That is, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process in the lowest region is set. According to this, since the compression ratio process in the lowest region is performed regardless of the alcohol concentration in the fuel, the compression ratio of the internal combustion engine 1 does not become excessively high with respect to the alcohol concentration in the fuel. Therefore, knocking of the internal combustion engine 1 that occurs due to an excessively high compression ratio of the internal combustion engine 1 with respect to the alcohol concentration in the fuel can be prevented.

  Next, the failure compression ratio process setting control routine according to this embodiment will be described. FIG. 6 is a flowchart showing a failure compression ratio process setting control routine according to this embodiment. This routine is repeatedly executed every predetermined time. The ECU 21 that executes this routine corresponds to the failure compression ratio process setting means of the present invention.

  In step S101, the ECU 21 determines whether or not the alcohol concentration sensor 13 has failed. For example, it is determined that the alcohol concentration sensor 13 has failed when the control amount such as the fuel injection amount to the internal combustion engine 1 fluctuates without stability or when the output value of the alcohol concentration sensor 13 exceeds a predetermined range. . The ECU 21 that processes this step corresponds to the failure detection means of the present invention. If an affirmative determination is made in step S101 that the alcohol concentration sensor 13 has failed, the process proceeds to step S102. If it is determined in step S101 that the alcohol concentration sensor 13 has not failed, the process proceeds to step S105.

  In step S102, the ECU 21 selects the map of FIG. 4 when the alcohol concentration in the fuel is 0%, that is, only gasoline is used as the fuel.

  In step S103, the ECU 21 acquires the operating state of the internal combustion engine 1.

  In step S104, the ECU 21 changes the compression ratio of the internal combustion engine 1 according to the operating state of the internal combustion engine 1 acquired in step S103 based on the map of FIG. 4 when only gasoline is used as the fuel, and the alcohol concentration is 0%. The compression ratio processing is performed. Then, after the processing of this step, this routine is once ended.

  On the other hand, in step S105, the ECU 21 detects the alcohol concentration in the fuel by the alcohol concentration sensor 13, and selects a map of the detected alcohol concentration.

  In step S106, the ECU 21 acquires the operating state of the internal combustion engine 1.

  In step S107, the ECU 21 changes the compression ratio of the internal combustion engine 1 according to the operating state of the internal combustion engine 1 acquired in step S106 based on the map selected in step S105, and performs the compression ratio process with the detected alcohol concentration. . Then, after the processing of this step, this routine is once ended.

  According to this routine described above, the failure of the alcohol concentration sensor 13 can be detected, and when the failure of the alcohol concentration sensor 13 is detected, the compression ratio processing can be performed based on a map in the case of using only gasoline as fuel. it can.

<Example 2>
Next, Example 2 will be described. In this embodiment, a three-dimensional map of the compression ratio of the internal combustion engine 1 corresponding to the alcohol concentration in the fuel and the operating state of the internal combustion engine 1 is provided, and the compression ratio of the internal combustion engine 1 is directly obtained from this map. . In this embodiment, the characteristic part will be described, and the other parts are the same as those in the above embodiment, and the description thereof will be omitted.

  Also in this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process of the internal combustion engine 1 is set to a compression ratio process when the alcohol concentration in the fuel is 0%, that is, only gasoline is used as the fuel. I did it.

  According to the present embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process of the internal combustion engine 1 is set to the compression ratio process when only gasoline is used as fuel. Specifically, in this embodiment, the alcohol concentration in the fuel to be taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 is set to 0%. Then, compression ratio processing for changing the compression ratio based on the three-dimensional map of the compression ratio of the internal combustion engine 1 is performed.

  Again, the alcohol concentration in the fuel is 0%, that is, the compression ratio process when only gasoline is used as the fuel is the highest compared to the compression ratio process when the alcohol is contained in the fuel as shown in the map of FIG. The compression ratio processing is performed on the low compression ratio side where the compression ratio side is not used. That is, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio process in the lowest region is set. According to this, since the compression ratio process in the lowest region is performed regardless of the alcohol concentration in the fuel, the compression ratio of the internal combustion engine 1 does not become excessively high with respect to the alcohol concentration in the fuel. Therefore, knocking of the internal combustion engine 1 that occurs due to an excessively high compression ratio of the internal combustion engine 1 with respect to the alcohol concentration in the fuel can be prevented.

  Next, the failure compression ratio process setting control routine according to this embodiment will be described. FIG. 7 is a flowchart showing a failure compression ratio process setting control routine according to this embodiment. This routine is repeatedly executed every predetermined time. The ECU 21 that executes this routine corresponds to the failure compression ratio process setting means of the present invention.

  In step S201, the ECU 21 determines whether or not the alcohol concentration sensor 13 has failed. If an affirmative determination is made in step S201 that the alcohol concentration sensor 13 has failed, the process proceeds to step S202. If it is determined in step S201 that the alcohol concentration sensor 13 has not failed, the process proceeds to step S203.

  In step S202, the ECU 21 sets the alcohol concentration in the fuel taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to an alcohol concentration of 0%.

  In step S203, the ECU 21 detects the alcohol concentration in the fuel by the alcohol concentration sensor 13, and sets the alcohol concentration taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to the detected alcohol concentration.

  In step S204, the ECU 21 acquires the operating state of the internal combustion engine 1.

  In step S205, the ECU 21 compresses the internal combustion engine 1 according to the alcohol concentration set in step S202 or step S203 and the operating state of the internal combustion engine 1 acquired in step 204 based on the three-dimensional map of the compression ratio of the internal combustion engine 1. The ratio is changed and the compression ratio process is performed at the set alcohol concentration. Then, after the processing of this step, this routine is once ended.

  According to this routine described above, the failure of the alcohol concentration sensor 13 can be detected, and when the failure of the alcohol concentration sensor 13 is detected, the compression ratio processing when only gasoline is used as fuel can be performed.

<Example 3>
Next, Example 3 will be described. In this embodiment, when a failure of the alcohol concentration sensor 13 is detected, if the compression ratio processing of the internal combustion engine 1 is changed according to the alcohol concentration before the failure detection and knocking is detected thereafter, the compression ratio of the internal combustion engine 1 is detected. Processing is set to compression ratio processing when only gasoline is used as fuel. In this embodiment, the characteristic part will be described, and the other parts are the same as those in the above embodiment, and the description thereof will be omitted.

  In this embodiment, as shown in FIG. 1, a knock sensor 24 for detecting knocking occurring in the internal combustion engine 1 is provided. A knock sensor 24 is connected to the ECU 21 via electrical wiring, and an output signal of the knock sensor 24 is input to the ECU 21. The knock sensor 24 of this embodiment corresponds to the knocking detection means of the present invention.

  In this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio processing of the internal combustion engine 1 is changed according to the alcohol concentration detected by the alcohol concentration sensor 13 before the failure is detected, and then the knock sensor 24 is changed. When knocking is detected, the compression ratio process of the internal combustion engine 1 is set to a compression ratio process when the alcohol concentration in the fuel is 0%, that is, only gasoline is used as the fuel.

  According to the present embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio processing of the internal combustion engine 1 is changed according to the alcohol concentration detected by the alcohol concentration sensor 13 before the failure detection, and the compression ratio processing is suitable. Can be achieved. Thereby, it can suppress that the compression ratio of the internal combustion engine 1 becomes low too much, and can optimize a fuel consumption and power performance more. However, when the knock sensor 24 detects knocking thereafter, the compression ratio processing of the internal combustion engine 1 is set to the compression ratio processing when only gasoline is used as the fuel, and the lowest region is set regardless of the alcohol concentration contained in the fuel. Perform compression ratio processing. Thereby, knocking of the internal combustion engine 1 can be prevented.

  Next, the failure compression ratio process setting control routine according to this embodiment will be described. FIG. 8 is a flowchart showing a failure compression ratio process setting control routine according to this embodiment. This routine is repeatedly executed every predetermined time. The ECU 21 that executes this routine corresponds to the failure compression ratio process setting means of the present invention.

  In step S301, the ECU 21 determines whether or not the alcohol concentration sensor 13 has failed. If an affirmative determination is made in step S301 that the alcohol concentration sensor 13 has failed, the process proceeds to step S302. If it is determined in step S301 that the alcohol concentration sensor 13 has not failed, the process proceeds to step S303.

  In step S302, the ECU 21 sets the alcohol concentration in the fuel taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to the alcohol concentration detected by the alcohol concentration sensor 13 before failure detection.

  In step S303, the ECU 21 detects the alcohol concentration in the fuel by the alcohol concentration sensor 13, and sets the alcohol concentration taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to the detected alcohol concentration.

  In step S304, the ECU 21 acquires the operating state of the internal combustion engine 1.

  In step S305, the ECU 21 compresses the internal combustion engine 1 according to the alcohol concentration set in step S302 or step S303 and the operating state of the internal combustion engine 1 acquired in step 304 based on the three-dimensional map of the compression ratio of the internal combustion engine 1. The ratio is changed and the compression ratio process is performed at the set alcohol concentration.

  In step S306, the ECU 21 determines whether knocking has occurred in the internal combustion engine 1. Knocking is detected by a knock sensor 24. If it is determined in step S306 that knocking has occurred, the process proceeds to step S307. If it is determined in step S306 that knocking has not occurred, this routine is temporarily terminated.

  In step S307, the ECU 21 sets the alcohol concentration in the fuel taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to an alcohol concentration of 0%.

  In step S308, the ECU 21 acquires the operating state of the internal combustion engine 1.

  In step S309, the ECU 21 compresses the internal combustion engine 1 according to the alcohol concentration of 0% set in step S307 and the operating state of the internal combustion engine 1 acquired in step 308 based on the three-dimensional map of the compression ratio of the internal combustion engine 1. The ratio is changed, and the compression ratio process is performed at an alcohol concentration of 0%. Then, after the processing of this step, this routine is once ended.

  According to the routine described above, the failure of the alcohol concentration sensor 13 can be detected, and when the failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 is temporarily determined according to the alcohol concentration detected before the failure detection. It is possible to change the processing and optimize the compression ratio processing. However, when knocking is subsequently detected, the compression ratio process can be performed when only gasoline is used as the fuel.

<Example 4>
Next, Example 4 will be described. In this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 is fixed to the lowest compression ratio in the compression ratio process when only gasoline is used as fuel. In this embodiment, the characteristic part will be described, and the other parts are the same as those in the above embodiment, and the description thereof will be omitted.

  In this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 is set to the lowest compression used in the compression ratio processing when the alcohol concentration in the fuel is 0%, that is, only gasoline is used as the fuel. The ratio was fixed.

  According to this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 is fixed to the minimum compression ratio used in the compression ratio process when only gasoline is used as fuel. Specifically, in this embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 employs the alcohol concentration in the fuel of 0% and the minimum compression ratio at the maximum engine load, The internal combustion engine 1 is operated in a state in which the compression ratio process for changing the compression ratio is not performed and the minimum compression ratio is fixed.

  Here, the alcohol concentration in the fuel is 0%, that is, the minimum compression ratio used in the compression ratio processing when only gasoline is used as the fuel is the compression ratio processing when alcohol is contained in the fuel as shown in the map of FIG. In the map of compression ratio processing on the low compression ratio side where the highest compression ratio side is not used compared to the above, the minimum compression ratio in the region where the internal combustion engine 1 is at the maximum engine load. For example, if the map of FIG. 4 is used, the minimum compression ratio is 8. As described above, when a failure of the alcohol concentration sensor 13 is detected, the internal combustion engine 1 is operated while being fixed at the minimum compression ratio. According to this, the compression ratio of the internal combustion engine 1 does not become excessively high with respect to the alcohol concentration in the fuel because the compression ratio is fixed regardless of the alcohol concentration in the fuel. Therefore, knocking of the internal combustion engine 1 that occurs due to an excessively high compression ratio of the internal combustion engine 1 with respect to the alcohol concentration in the fuel can be prevented.

  Next, the failure compression ratio process setting control routine according to this embodiment will be described. FIG. 9 is a flowchart showing a failure compression ratio process setting control routine according to this embodiment. This routine is repeatedly executed every predetermined time. The ECU 21 that executes this routine corresponds to the failure compression ratio process setting means of the present invention.

  In step S401, the ECU 21 determines whether or not the alcohol concentration sensor 13 has failed. If an affirmative determination is made in step S401 that the alcohol concentration sensor 13 has failed, the process proceeds to step S402. If it is determined in step S401 that the alcohol concentration sensor 13 has not failed, the process proceeds to step S403.

  In step S <b> 402, the ECU 21 calculates a minimum compression ratio to be adopted at a maximum engine load with an alcohol concentration of 0% in the fuel from a three-dimensional map of the compression ratio of the internal combustion engine 1, and the compression ratio of the internal combustion engine 1 is calculated as the minimum compression. Fixed to the ratio. Regardless of the operating state of the internal combustion engine 1, the compression ratio of the internal combustion engine 1 is maintained at the minimum compression ratio. After the processing of this step, this routine is once ended.

  In step S403, the ECU 21 detects the alcohol concentration in the fuel by the alcohol concentration sensor 13, and sets the alcohol concentration taken into the three-dimensional map of the compression ratio of the internal combustion engine 1 to the detected alcohol concentration.

  In step S404, the ECU 21 acquires the operating state of the internal combustion engine 1.

In step S405, the ECU 21 is based on the three-dimensional map of the compression ratio of the internal combustion engine 1.
The compression ratio of the internal combustion engine 1 is changed in accordance with the alcohol concentration set in step S403 and the operating state of the internal combustion engine 1 acquired in step 404, and the compression ratio processing with the detected alcohol concentration is performed. Then, after the processing of this step, this routine is once ended.

  According to this routine described above, the failure of the alcohol concentration sensor can be detected, and when the failure of the alcohol concentration sensor is detected, it can be fixed to the lowest compression ratio when only gasoline is used as fuel.

  In the above embodiment, when a failure of the alcohol concentration sensor 13 is detected, the compression ratio of the internal combustion engine 1 is immediately fixed to the lowest compression ratio in the compression ratio process when only gasoline is used as fuel. . However, the present invention is not limited to this. When a failure of the alcohol concentration sensor 13 is detected as in the third embodiment, the compression ratio processing of the internal combustion engine 1 is changed according to the alcohol concentration before the failure detection, and then knocking is detected. The ratio may be fixed to the minimum compression ratio used in the compression ratio process when only gasoline is used as the fuel.

  In the above embodiment, the compression ratio of the internal combustion engine 1 is fixed to the minimum compression ratio used in the compression ratio process when only gasoline is used as fuel. However, the present invention is not limited to this. The compression ratio of the internal combustion engine 1 may be fixed to any compression ratio used in the compression ratio process when only gasoline is used as fuel. Since the compression ratio used in the compression ratio process when only gasoline is used as fuel is a low compression ratio, the compression ratio of the internal combustion engine 1 does not become excessively high with respect to the alcohol concentration in the fuel. . Therefore, knocking of the internal combustion engine 1 that occurs due to an excessively high compression ratio of the internal combustion engine 1 with respect to the alcohol concentration in the fuel can be prevented.

  In the above embodiment, the alcohol concentration sensor 13 is arranged, and the alcohol concentration in the fuel is detected from the output value of the alcohol concentration sensor 13. However, it is not limited to this. For example, the alcohol concentration in the fuel may be detected from the output value of the air-fuel ratio sensor.

  The variable compression ratio internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

1 is a diagram illustrating a schematic configuration of an internal combustion engine according to a first embodiment. FIG. 3 is a diagram illustrating a compression ratio according to an operating state of the internal combustion engine according to the first embodiment. The figure which shows the compression ratio according to the alcohol concentration in the fuel which concerns on Example 1. FIG. The figure which shows the selectable compression ratio of the alcohol concentration in the fuel which concerns on Example 1 0%. The figure which shows the selectable compression ratio of 100% of alcohol concentration in the fuel which concerns on Example 1. FIG. 7 is a flowchart illustrating a failure compression ratio process setting control routine according to the first embodiment. 9 is a flowchart showing a failure compression ratio process setting control routine according to the second embodiment. 10 is a flowchart illustrating a failure compression ratio process setting control routine according to a third embodiment. 9 is a flowchart illustrating a failure compression ratio process setting control routine according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Cylinder head 4 Intake port 5 Intake pipe 6 Intake valve 7 Exhaust port 8 Exhaust pipe 10 Exhaust valve 10 Fuel injection valve 11 Fuel supply pipe 12 Fuel tank 13 Alcohol concentration sensor 14 Spark plug 15 Crankshaft 16 Connecting rod 17 Piston 18 Variable compression ratio mechanism 18a Shaft portion 18b Cam portion 18c Movable bearing portion 18d Worm wheel 18e Worm 18f Motor 19 Cylinder block 20 Crankcase 21 ECU
22 Crank position sensor 23 Accelerator position sensor 24 Knock sensor

Claims (4)

Alcohol concentration detection means for detecting the alcohol concentration in fuel containing alcohol in gasoline;
A variable compression ratio mechanism for changing the compression ratio of the internal combustion engine;
With
In the variable compression ratio internal combustion engine that changes the compression ratio processing of the internal combustion engine using the compression ratio variable mechanism according to the alcohol concentration detected by the alcohol concentration detection means,
Failure detection means for detecting a failure of the alcohol concentration detection means;
When the failure detection means detects a failure of the alcohol concentration detection means, the compression ratio process setting means at the time of setting the compression ratio process of the internal combustion engine to the compression ratio process when using only gasoline as fuel,
A variable compression ratio internal combustion engine comprising:   The variable compression ratio internal combustion engine according to claim 1, wherein the compression ratio variable mechanism is configured to relatively displace the cylinder block with respect to the crankcase. A knocking detecting means for detecting knocking generated in the internal combustion engine;
The failure compression ratio processing setting means compresses the internal combustion engine according to the alcohol concentration detected by the alcohol concentration detection means before the failure detection when the failure detection means detects a failure of the alcohol concentration detection means. The ratio processing is changed, and when the knocking detection means detects knocking after that, the compression ratio processing of the internal combustion engine is set to the compression ratio processing when only gasoline is used as fuel. 2. The variable compression ratio internal combustion engine according to 2.   The failure compression ratio processing setting means uses the compression ratio of the internal combustion engine and only gasoline as the fuel when the compression ratio processing of the internal combustion engine is set to the compression ratio processing when only gasoline is used as fuel. The variable compression ratio internal combustion engine according to any one of claims 1 to 3, wherein the compression ratio is fixed to a compression ratio used in the compression ratio process.

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