Fuel shortage detection device of internal combustion engine and saddle-type vehicle

Abstract

To provide a fuel shortage detection device of an internal combustion engine which can detect fuel shortage on the basis of an air-fuel ratio of an exhaust gas.SOLUTION: A fuel shortage detection device of an internal combustion engine has: an air-fuel ratio determination part 61 for determining whether or not an air-fuel ratio of an exhaust gas is equal to or higher than a first threshold TH1 on the basis of a detection result of an O2 sensor 78; a cumulative time calculation part 62 for calculating a cumulative time Ta of a time at which it is determined that the air-fuel ratio is equal to or higher than the first threshold TH1; a cumulative time reset part 63 for resetting the cumulative time Ta at each preset time interval B; a cumulative time determination part 64 for determining whether or not the cumulative time Ta is equal to or longer than a second threshold TH2; and a fuel shortage determination part 67 for determining that fuel is shorted when the cumulative time Ta reaches the second threshold TH2 or longer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel deficiency detection device for an internal combustion engine and a straddle-type vehicle. [Background technology]

[0002] Conventionally, there is known a device that counts the number of times that the air-fuel ratio of exhaust gas is equal to or greater than a preset threshold, and determines that the internal combustion engine is misfiring when the counted number reaches a predetermined number. Incidentally, there are various causes of misfire, and in the case of fuel shortage, there is a mixture of a state in which fuel is injected from the injector and a state in which fuel is not injected. Therefore, in the case of fuel shortage, a lean state in which the air-fuel ratio is equal to or greater than a certain level does not necessarily continue.

[0003] Patent Document 1 discloses an engine control device including an air-fuel ratio detection unit that detects the air-fuel ratio of the engine, a rotational fluctuation derivation unit that derives a rotational fluctuation value of the engine, and a fuel shortage misfire determination unit that determines whether the engine is misfiring due to a lack of fuel (hereinafter referred to as "starved fuel"). When the air-fuel ratio is equal to or greater than a predetermined air-fuel ratio threshold, the fuel shortage misfire determination unit counts the number of times the engine rotational fluctuation value is equal to or greater than the predetermined rotational fluctuation threshold, and determines that the engine is misfiring due to starved fuel when the counted number reaches a preset count threshold.

[0004] The engine control device disclosed in Patent Document 1 has a prerequisite that the air-fuel ratio of the exhaust gas is equal to or greater than an air-fuel ratio threshold, and when this prerequisite is met, determines whether the engine is lacking fuel based on the engine rotation fluctuation value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-25158 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a fuel shortage detection device for an internal combustion engine that can detect a fuel shortage based on the air-fuel ratio of exhaust gas, and a saddle-type vehicle equipped with the same. [Means for solving the problem]

[0007] The fuel shortage detection device for an internal combustion engine disclosed herein is disposed in an exhaust passage of the internal combustion engine and detects the oxygen concentration of gas flowing through the exhaust passage. 2 A sensor and the O 2 and a determination device comprising a computer connected to the sensor. 2 The fuel consumption control system includes an air-fuel ratio determination unit that determines whether the air-fuel ratio of the gas is equal to or greater than a predetermined first threshold based on a detection result of the sensor, an accumulated time calculation unit that calculates an accumulated time during which the air-fuel ratio determination unit has determined that the air-fuel ratio of the gas is equal to or greater than the first threshold, an accumulated time reset unit that resets the accumulated time accumulated by the accumulated time calculation unit at predetermined time intervals, an accumulated time determination unit that determines whether the accumulated time is equal to or greater than a predetermined second threshold, and a fuel shortage determination unit that determines that fuel is insufficient when the accumulated time becomes equal to or greater than the second threshold.

[0008] When fuel is insufficient in an internal combustion engine, the lean state does not necessarily continue, and lean and non-lean states may be repeated. However, even in this case, the lean state is repeated, so the accumulated time of the lean state becomes large. According to the above-mentioned fuel shortage detection device, it is possible to detect a fuel shortage based on the accumulated time of the lean state in which the air-fuel ratio is equal to or greater than the first threshold value. However, when the fuel supply is unstable or when the O 2 When the sensor detection accuracy is relatively low, the O 2There may be cases where the sensor detection result temporarily determines that the engine is in a lean state. In such cases, the lean state does not last long, but as the time of the lean state accumulates, the accumulated time eventually reaches or exceeds the second threshold, and there is a risk that the engine may erroneously determine that there is a fuel shortage. However, according to the fuel shortage detection device, the accumulated time is reset at predetermined time intervals. Therefore, the influence of a lean state caused by factors other than fuel shortage can be suppressed, and the accuracy of fuel shortage detection can be improved.

[0009] The fuel shortage detection device may include a rotation speed sensor connected to the determination device and detecting the rotation speed of the internal combustion engine. The determination device may include a fluctuation value calculation unit that calculates a fluctuation value of the rotation speed of the internal combustion engine, and a fluctuation value determination unit that determines whether the fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than a predetermined third threshold. The fuel shortage determination unit may be configured to determine that there is a fuel shortage when the accumulated time is equal to or greater than the second threshold and the fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than the third threshold.

[0010] When the internal combustion engine is short of fuel, the rotation speed of the internal combustion engine fluctuates. According to the fuel shortage detection device, the fluctuation in the rotation speed of the internal combustion engine is taken into consideration, so that erroneous judgment is unlikely to occur. Therefore, it is possible to further improve the accuracy of detection of fuel shortage.

[0011] The fuel shortage detection device may include a fuel sensor connected to the determination device and detecting whether the amount of fuel stored in the fuel tank is equal to or less than a predetermined fourth threshold. The fuel shortage determination unit may be configured to determine that there is a fuel shortage when the accumulated time is equal to or more than the second threshold and the amount of fuel stored in the fuel tank is equal to or less than the fourth threshold.

[0012] According to the above fuel shortage detection device, the remaining amount of fuel in the fuel tank is also taken into consideration, making it difficult for erroneous determinations to occur, thereby further improving the accuracy of fuel shortage detection.

[0013] The fuel shortage detection device may include a rotation speed sensor connected to the determination device and detecting the rotation speed of the internal combustion engine, and a fuel sensor connected to the determination device and detecting whether the amount of fuel stored in the fuel tank is equal to or less than a predetermined fourth threshold. The determination device may include a fluctuation value calculation unit that calculates a fluctuation value of the rotation speed of the internal combustion engine, and a fluctuation value determination unit that determines whether the fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than a predetermined third threshold. The fuel shortage determination unit may be configured to determine that there is a fuel shortage when the accumulated time is equal to or greater than the second threshold, the fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than the third threshold, and the amount of fuel stored in the fuel tank is equal to or less than the fourth threshold.

[0014] According to the above fuel shortage detection device, since the fluctuation in the rotation speed of the internal combustion engine and the remaining amount of fuel in the fuel tank are taken into consideration, erroneous determination is unlikely to occur, and therefore the accuracy of fuel shortage detection can be further improved.

[0015] The saddle-type vehicle disclosed herein includes an internal combustion engine, drive wheels, a power transmission mechanism connecting the internal combustion engine and the drive wheels, and the fuel shortage detection device. Effect of the Invention

[0016] According to the present invention, it is possible to provide a fuel shortage detection device for an internal combustion engine that can detect a fuel shortage based on an air-fuel ratio, and a saddle-type vehicle equipped with the same. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a side view of a motorcycle according to an embodiment. [Diagram 2] FIG. 2 is a conceptual diagram showing an internal combustion engine, various sensors, and an ECU. [Diagram 3] FIG. 3 is a block diagram of the determination device. [Figure 4]Fig. 4(a) is a graph showing the relationship between elapsed time and engine speed. Fig. 4(b) is a graph showing the relationship between elapsed time and air-fuel ratio. Fig. 4(c) is a graph showing the relationship between elapsed time and the output value of the O2 sensor. Fig. 4(d) is a graph showing the relationship between elapsed time and the accumulated time during which the air-fuel ratio is detected to be equal to or greater than the first threshold. Fig. 4(e) is a time chart showing time interval B. [Diagram 5] FIG. 5 is a flowchart of the first determination method. [Figure 6] FIG. 6 is a graph showing the fluctuations in engine speed when the fuel runs short while the motorcycle is running. [Figure 7] FIG. 7 is a flowchart of the second determination method. [Figure 8] FIG. 8 is a flowchart of the third determination method. [Figure 9] FIG. 9 is a flowchart of the fourth determination method. [Figure 10] FIG. 10 is a block diagram of a determination device according to a modified example. [Figure 11] FIG. 11 is a flowchart of a determination method according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel shortage detection device for an internal combustion engine and a saddle-type vehicle will now be described with reference to the drawings. Fig. 1 is a side view of a motorcycle 1, which is an example of a saddle-type vehicle.

[0019] The motorcycle 1 includes a body frame 6 having a head pipe 6A, an internal combustion engine (hereinafter referred to as engine) 4, a fuel tank 2, a seat 3, a front wheel 8, and a rear wheel 10. The engine 4, the fuel tank 2, and the seat 3 are supported by the body frame 6. A steering shaft (not shown) is rotatably supported by the head pipe 6A. A handlebar 12 is fixed to the steering shaft. A front fork 7 is also fixed to the steering shaft. The front wheel 8 is connected to a lower end of the front fork 7. The rear wheel 10 is a drive wheel driven by the engine 4. The engine 4 and the rear wheel 10 are connected to each other by a chain 5 so that power can be transmitted. The chain 5 is an example of a power transmission mechanism that transmits the power of the engine 4 to the rear wheel 10. However, the power transmission mechanism is not limited to the chain 5, and may be a drive shaft, a transmission belt, or the like. A rear arm 9 is supported by the body frame 6 so as to be able to swing. The rear wheel 10 is connected to a rear end of the rear arm 9.

[0020] As shown in Fig. 2, the engine 4 includes a cylinder 21, a piston 22 disposed in the cylinder 21, a connecting rod 24 connected to the piston 22, and a crankshaft 23 connected to the connecting rod 24. The engine 4 also includes a combustion chamber 25, an ignition device 50, an intake valve 32, and an exhaust valve 42. An intake passage 30 including an intake pipe and the like, and an exhaust passage 40 including an exhaust pipe and the like are connected to the engine 4. A throttle valve 34 is disposed in the intake passage 30. A catalyst 44 is disposed in the exhaust passage 40.

[0021] A fuel pump 48 is disposed in the fuel tank 2. A fuel injection valve 52 is attached to the intake passage 30. The fuel pump 48 and the fuel injection valve 52 are connected by a fuel pipe 46.

[0022] The fuel tank 2 is provided with a fuel sensor 80 that detects whether the amount of fuel is equal to or less than a predetermined threshold. The intake passage 30 is provided with a pressure sensor 74. The engine 4 is provided with a rotation speed sensor 70 that detects the rotation speed of the crankshaft 23 (hereinafter referred to as engine rotation speed). The exhaust passage 40 is provided with an O2 sensor 70 that detects the oxygen concentration. 2 A sensor 78 is provided.

[0023] The motorcycle 1 includes an ECU (Electronic Control Unit) 90 that is a computer. The ECU 90 includes a CPU 91, a ROM 92, and a RAM 93. The ECU 90 controls the engine 4. In this embodiment, the ECU 90 also functions as a determination device 60 that determines whether the engine 4 is insufficient in fuel.

[0024] FIG. 3 is a block diagram of the determination device 60. The determination device 60 2 The determination device 60 is communicatively connected to the sensor 78, the rotation speed sensor 70, and the fuel sensor 80. 2 The determination device 60 is configured to obtain the air-fuel ratio of the gas (hereinafter referred to as exhaust gas) flowing through the exhaust passage 40 by receiving a signal from the sensor 78. The determination device 60 is also configured to obtain the engine rotation speed by receiving a signal from the rotation speed sensor 70. The determination device 60 is configured to obtain the amount of fuel stored in the fuel tank 2 (hereinafter simply referred to as the fuel amount) by receiving a signal from the fuel sensor 80.

[0025] The determination device 60 has an air-fuel ratio determination unit 61, an accumulated time calculation unit 62, an accumulated time reset unit 63, an accumulated time determination unit 64, a fluctuation value calculation unit 65, a fluctuation value determination unit 66, and a fuel shortage determination unit 67, by executing a computer program stored in the ROM 92 or the like. The determination device 60 also has a fuel shortage count storage unit 68 made of a non-volatile memory. The air-fuel ratio determination unit 61 is 2Based on the detection result of the sensor 78, it is determined whether the air-fuel ratio A / F of the exhaust gas is equal to or greater than a predetermined threshold value (hereinafter referred to as a first threshold value) TH1. The cumulative time calculation unit 62 calculates the cumulative time Ta of the time during which it is determined that the air-fuel ratio A / F is equal to or greater than the first threshold value TH1. The cumulative time reset unit 63 resets the cumulative time Ta accumulated by the cumulative time calculation unit 62 at every predetermined time interval B (i.e., sets the cumulative time Ta to zero). The cumulative time determination unit 64 determines whether the cumulative time Ta is equal to or greater than a predetermined threshold value (hereinafter referred to as a second threshold value) TH2. The fluctuation value calculation unit 65 calculates a fluctuation value DVe of the engine rotation speed. The fluctuation value determination unit 66 determines whether the fluctuation value DVe of the engine rotation speed is equal to or greater than a predetermined threshold value (hereinafter referred to as a third threshold value) TH3. The fuel shortage determination unit 67 determines that there is a fuel shortage when a predetermined determination condition is satisfied. The fuel shortage count storage unit 68 stores the number of times that it has been determined that there is a fuel shortage.

[0026] 4(a) to 4(d) are graphs showing the change in each parameter when fuel runs short while the motorcycle 1 is traveling. The horizontal axis of each graph represents elapsed time T. FIG. 4(a) is a graph showing the relationship between elapsed time T and engine rotation speed Ve. FIG. 4(b) is a graph showing the relationship between elapsed time T and air-fuel ratio A / F. FIG. 4(c) is a graph showing the relationship between elapsed time T and O 2 1 is a graph showing the relationship between the output value S of the sensor 78 and the temperature. 2 When the output value S of the sensor 78 is equal to or less than the threshold value S1, the air-fuel ratio A / F is deemed to be equal to or greater than the first threshold value TH1. Fig. 4(d) is a graph showing the relationship between the elapsed time T and the accumulated time Ta during which the air-fuel ratio A / F is detected to be equal to or greater than the first threshold value TH1. Fig. 4(e) shows the time interval B.

[0027] In the example shown in FIG. 4(a) to FIG. 4(d), at T=T1, the air-fuel ratio A / F becomes equal to or exceeds the first threshold value TH1, and the exhaust gas becomes lean (see FIG. 4(b)). When the exhaust gas becomes lean, the engine rotation speed Ve decreases (see FIG. 4(a)). As shown in FIG. 4(c), even before fuel shortage occurs, O 2 The output value S of the sensor 78 may fluctuate. 2The output value S of the sensor 78 may temporarily become equal to or less than the threshold value S1 indicating a lean state. However, since the lean state is not actually being observed (see FIG. 4(b)), 2 The state in which the output value S of the sensor 78 is equal to or less than the threshold value S1 does not continue for long. Therefore, the cumulative time Ta increases little by little, but does not become equal to or greater than the second threshold value TH2 during the limited time interval B (see FIG. 4(d)). On the other hand, when a fuel shortage actually occurs and the engine becomes lean, O 2 The state in which the output value S of the sensor 78 is equal to or less than the threshold value S1 continues. Therefore, the accumulated time Ta becomes equal to or greater than the second threshold value TH2 during the time interval B. In the example shown in FIG. 4(d), the accumulated time Ta becomes equal to the second threshold value TH2 when T=T2.

[0028] Therefore, in this embodiment, the fuel shortage determination unit 67 determines, as at least one of the determination conditions, whether the accumulated time Ta becomes equal to or greater than the second threshold value TH2 during the time interval B. The fuel shortage determination unit 67 determines that there is a fuel shortage at least when the accumulated time Ta becomes equal to or greater than the second threshold value TH2. Next, some examples of the determination method performed by the determination device 60 will be described.

[0029] (First Judgment Method) FIG. 5 is a flowchart of the first determination method. In the first determination method, in step S1, the air-fuel ratio determination unit 61 determines whether the air-fuel ratio A / F is equal to or greater than the first threshold value TH1. If the air-fuel ratio A / F is equal to or greater than the first threshold value TH1, the process proceeds to step S2. If the air-fuel ratio A / F is less than the first threshold value TH1, the process returns to step S1. In step S2, the cumulative time calculation unit 62 calculates the cumulative time Ta. Then, in step S3, the cumulative time determination unit 64 determines whether the cumulative time Ta is equal to or greater than the second threshold value TH2. If the cumulative time Ta is determined to be equal to or greater than the second threshold value TH2, the process proceeds to step S4. If the cumulative time Ta is determined to be less than the second threshold value TH2, the process proceeds to step S6. In step S4, the fuel shortage determination unit 67 determines that there is a fuel shortage. After that, in step S5, the number of times that it has been determined that there is a fuel shortage is added to the fuel shortage count storage unit 68. The number of times stored in the fuel shortage count storage unit 68 (the number of times it was determined that there was a fuel shortage) can be transferred as diagnostic data by a service technician or the like connecting a service tool to an on-board diagnostic device (OBD). In step S6, it is determined whether the count time Ti is equal to or greater than the time interval B. If it is determined that the count time Ti is equal to or greater than the time interval B, the cumulative time Ta and the count time Ti are reset in step S7, and the process returns to step S1. That is, the cumulative time Ta and the count time Ti are reset to zero, and the process returns to step S1. If it is determined in step S6 that the count time Ti is less than the time interval B, the process returns to step S1.

[0030] As mentioned above, even if there is no fuel shortage, 2 There may be a case where the output value S of the sensor 78 temporarily becomes equal to or smaller than the threshold value S1. Even if there is no fuel shortage, it may be temporarily regarded as being in a lean state. 2 If fuel shortage is judged based only on the output value S of the sensor 78, an erroneous judgment may occur. On the other hand, if there is no fuel shortage, the state regarded as a lean state will not continue for a long time, but if there is a fuel shortage, the state regarded as a lean state will continue for a long time. According to the above judgment method, the state regarded as a lean state (i.e., O 2The fuel shortage is judged based on the accumulated time Ta during which the air-fuel ratio A / F is equal to or greater than the first threshold value TH1 based on the detection result of the sensor 78. Therefore, the influence of a temporary lean state caused by factors other than fuel shortage can be suppressed. Therefore, the accuracy of fuel shortage detection can be improved.

[0031] (Second Judgment Method) Fig. 6 is a graph showing the engine speed fluctuation value DVe when fuel is insufficient while the motorcycle 1 is traveling. Note that the engine speed fluctuation value DVe here is DVe=Ve1-Ve2, where the engine speeds before and after the fluctuation are Ve1 and Ve2, respectively. As shown in Fig. 6, when the engine is in a lean state at T=T1, the engine speed fluctuation value DVe becomes equal to or greater than a threshold value (hereinafter referred to as a third threshold value) TH3. In the second determination method, fuel shortage is determined based on the engine speed fluctuation value DVe in addition to the cumulative time Ta described above.

[0032] FIG. 7 is a flowchart of the second determination method. In the second determination method, the above-mentioned steps S1 to S7 are executed as in the first determination method. However, in the second determination method, if it is determined in step S3 that the cumulative time Ta is equal to or greater than the second threshold value TH2, the process proceeds to step S31, where the fuel shortage determination unit 67 further determines whether or not the engine speed fluctuation value DVe is equal to or greater than the third threshold value TH3. If it is determined that the engine speed fluctuation value DVe is equal to or greater than the third threshold value TH3, the process proceeds to step 4, where the fuel shortage determination unit 67 determines that there is a fuel shortage. If it is determined in step S31 that the engine speed fluctuation value DVe is less than the third threshold value TH3, the process proceeds to step S6. The order of the processes in steps S3 and S31 is not particularly limited. Step S31 may be performed before step S3, or may be performed simultaneously with step S3.

[0033] As described above, according to the second determination method, fuel shortage is determined based on both the cumulative time Ta in the lean state and the fluctuation value DVe of the engine rotation speed. Since the fluctuation of the engine rotation speed is also taken into consideration, erroneous determination is unlikely to occur. Therefore, the detection accuracy of fuel shortage can be further improved.

[0034] (Third Judgment Method) As described above, the fuel sensor 80 detects whether the amount of fuel in the fuel tank 2 is equal to or less than the threshold value. In this embodiment, the threshold value is not zero, but is set to a predetermined value as the amount of fuel that allows the motorcycle 1 to travel a predetermined distance, so that the rider can be warned before the fuel tank 2 becomes empty. Hereinafter, this threshold value is referred to as a fourth threshold value TH4. If the amount of fuel in the fuel tank 2 (hereinafter simply referred to as the fuel amount) M is greater than the fourth threshold value TH4, fuel shortage does not occur. In the third determination method, fuel shortage is determined based on the detection result of the fuel sensor 80 in addition to the above-mentioned accumulated time Ta.

[0035] FIG. 8 is a flowchart of the third determination method. In the third determination method, the above-mentioned steps S1 to S7 are executed as in the first determination method. However, in the third determination method, if it is determined in step S3 that the cumulative time Ta is equal to or greater than the second threshold value TH2, the process proceeds to step S32, where the fuel shortage determination unit 67 receives a signal from the fuel sensor 80 and determines whether the fuel amount M is equal to or less than the fourth threshold value TH4. If it is determined that the fuel amount M is equal to or less than the fourth threshold value TH4, the process proceeds to step 4, where the fuel shortage determination unit 67 determines that there is a fuel shortage. If it is determined in step S32 that the fuel amount M is greater than the fourth threshold value TH4, the process proceeds to step S6. The order of the processes in steps S3 and S32 is not particularly limited. Step S32 may be performed before step S3, or may be performed simultaneously with step S3.

[0036] According to the third determination method, fuel shortage is determined based on both the accumulated time Ta in the lean state and the amount of fuel M in the fuel tank 2. Since the amount of fuel M in the fuel tank 2 is also taken into consideration, erroneous determination is unlikely to occur. Therefore, it is possible to further improve the accuracy of detecting fuel shortage.

[0037] The method of determining whether or not there is a shortage of fuel using the fuel sensor 80 may be selected from the following methods 1 to 3, for example. Method 1: Based on the resistance value of the fuel sensor 80, it is determined that there is a fuel shortage when the threshold value A≦the resistance value. Method 2: After it is determined that there is a fuel shortage by Method 1, it is determined that there is a fuel shortage during the period from when the resistance value becomes greater than the threshold value A due to refueling until when a certain distance has been traveled. Method 3: After it is determined that there is a fuel shortage by Method 1, the travel distance after that determination is accumulated from zero. If the accumulated distance satisfies threshold B≦accumulated distance≦threshold C, it is determined that there is a fuel shortage.

[0038] (Fourth Judgment Method) FIG. 9 is a flowchart of the fourth determination method. In the fourth determination method, fuel shortage is determined based on the accumulated time Ta, the engine speed fluctuation value DVe, and the detection result of the fuel sensor 80. In the fourth determination method, the above-mentioned steps S1 to S7 are executed as in the first determination method. However, in the fourth determination method, if it is determined in step S3 that the accumulated time Ta is equal to or greater than the second threshold value TH2, the process proceeds to step S31, where the fuel shortage determination unit 67 further determines whether or not the engine speed fluctuation value DVe is equal to or greater than the third threshold value TH3. If it is determined that the engine speed fluctuation value DVe is equal to or greater than the third threshold value TH3, the process proceeds to step S32, where the fuel shortage determination unit 67 receives a signal from the fuel sensor 80 and determines whether or not the fuel amount M is equal to or less than the fourth threshold value TH4. If it is determined that the fuel amount M is equal to or less than the fourth threshold value TH4, the process proceeds to step 4, where the fuel shortage determination unit 67 determines that there is a fuel shortage. When it is determined in step S31 that the fluctuation value DVe of the engine rotation speed is less than the third threshold value TH3, or when it is determined in step S32 that the fuel amount M is greater than the fourth threshold value TH4, the process proceeds to step S6. Note that the order of the processes in steps S3, S31, and S32 is not particularly limited.

[0039] As described above, according to the fourth determination method, fuel shortage is determined based on the cumulative time Ta of the lean state, the fluctuation value DVe of the engine rotation speed, and the amount of fuel M in the fuel tank 2. Since not only the cumulative time Ta of the lean state but also the fluctuation of the engine rotation speed and the amount of fuel in the fuel tank 2 are taken into consideration, erroneous determination is unlikely to occur. Therefore, it is possible to further improve the accuracy of detecting fuel shortage.

[0040] Although the fuel shortage detection device and the straddle-type vehicle according to one embodiment have been described above, the present invention is not limited to the above embodiment and can be embodied in various other forms.

[0041] In the above embodiment, the determination device 60 is configured by the ECU 90 that controls the engine 4, but the determination device 60 may be separate from the ECU 90. The determination device 60 may be configured by a computer separate from the ECU 90.

[0042] In the above embodiment, when the fuel shortage determination unit 67 determines that there is a fuel shortage, the number of times that the fuel shortage has been determined is stored in the fuel shortage count storage unit 68, but the method of using the determination result is not particularly limited. For example, when it is determined that there is a fuel shortage, the rider or the like may be notified that there is a fuel shortage. As shown in FIG. 10, the motorcycle 1 may include a notification device 77 capable of communicating with the determination device 60. The first to fourth determination methods described above may have a step S51 in which the notification device 77 notifies the rider or the like of the fuel shortage instead of the above step S5 (see FIG. 11). Note that the configuration of the notification device 77 and the notification method are not limited at all. The notification device 77 may notify the rider, for example, by turning on a warning light, displaying on a display device, outputting sound from a speaker, or the like.

[0043] A saddle-type vehicle is a vehicle on which a rider straddles and rides. The saddle-type vehicle is not limited to the motorcycle 1. The saddle-type vehicle may be, for example, a three-wheeled motor vehicle, an ATV (All Terrain vehicle), or a snowmobile. [Explanation of symbols]

[0044] 1...motorcycle (saddle-type vehicle), 4...internal combustion engine, 5...chain (power transmission mechanism), 10...rear wheel (drive wheel), 40...exhaust passage, 60...determination device, 61...air-fuel ratio determination section, 62...accumulated time calculation section, 63...accumulated time reset section, 64...accumulated time determination section, 65...variation value calculation section, 66...variation value determination section, 67...fuel shortage determination section, 70...rotational speed sensor, 78...O 2 Sensor, 80...Fuel sensor

Claims

1. An O2 concentration detector is disposed in an exhaust passage of an internal combustion engine and detects the oxygen concentration of gas flowing through the exhaust passage. ２ A sensor; The above O ２ A determination device including a computer connected to the sensor, The determination device includes: The above O ２ an air-fuel ratio determination unit that determines whether or not an air-fuel ratio of the gas is equal to or greater than a predetermined first threshold value based on a detection result of the sensor; an accumulated time calculation unit that calculates an accumulated time during which the air-fuel ratio determination unit has determined that the air-fuel ratio of the gas is equal to or greater than the first threshold; an accumulated time reset unit that resets the accumulated time accumulated by the accumulated time calculation unit at every predetermined time interval; an accumulated time determination unit that determines whether the accumulated time is equal to or greater than a predetermined second threshold; a fuel shortage determination unit that determines that fuel is insufficient when the cumulative time becomes equal to or greater than the second threshold value; A fuel deficiency detection device for an internal combustion engine, comprising:

2. a rotation speed sensor connected to the determination device and configured to detect a rotation speed of the internal combustion engine; The determination device includes: A fluctuation value calculation unit that calculates a fluctuation value of a rotation speed of the internal combustion engine; a fluctuation value determination unit that determines whether or not a fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than a predetermined third threshold value, 2. The fuel deficiency detection device for an internal combustion engine according to claim 1, wherein the fuel deficiency determination unit is configured to determine that fuel is insufficient when the accumulated time is equal to or greater than the second threshold value and when a fluctuation value of the rotational speed of the internal combustion engine is equal to or greater than the third threshold value.

3. a fuel sensor connected to the determination device for detecting whether an amount of fuel stored in the fuel tank is equal to or less than a predetermined fourth threshold value; 2. The fuel deficiency detection device for an internal combustion engine according to claim 1, wherein the fuel deficiency determination unit is configured to determine that fuel is insufficient when the accumulated time is equal to or greater than the second threshold value and the amount of fuel stored in the fuel tank is equal to or less than the fourth threshold value.

4. a rotation speed sensor connected to the determination device and detecting a rotation speed of the internal combustion engine; a fuel sensor connected to the determination device for detecting whether an amount of fuel stored in the fuel tank is equal to or less than a predetermined fourth threshold value, The determination device includes: A fluctuation value calculation unit that calculates a fluctuation value of a rotation speed of the internal combustion engine; a fluctuation value determination unit that determines whether or not a fluctuation value of the rotation speed of the internal combustion engine is equal to or greater than a predetermined third threshold value, 2. The fuel deficiency detection device for an internal combustion engine according to claim 1, wherein the fuel deficiency determination unit is configured to determine that fuel is insufficient when the accumulated time is equal to or greater than the second threshold value, the fluctuation value of the rotational speed of the internal combustion engine is equal to or greater than the third threshold value, and the amount of fuel stored in the fuel tank is equal to or less than the fourth threshold value.

5. An internal combustion engine; Drive wheels and a power transmission mechanism connecting the internal combustion engine and the drive wheels; A fuel shortage detection device for an internal combustion engine according to any one of claims 1 to 4, A saddle-type vehicle equipped with:

Images