Control device of hybrid vehicle

Abstract

To provide a control device of a hybrid vehicle which is capable of preventing water immersion to an exhaust pipe without increasing the number of components.SOLUTION: A hybrid vehicle comprises an internal combustion engine, a battery which accumulates electrical power and an electric motor which generates driving force by using the electric power accumulated in the battery. A control device of the hybrid vehicle runs the hybrid vehicle in mode selected from first mode that the hybrid vehicle travels in such a condition that the internal combustion engine is operated and second mode that the hybrid vehicle travels by the electric motor generating the driving force in such a condition that the internal combustion engine is stopped. Furthermore, the control device determines whether or not possibility that the exhaust pipe of the hybrid vehicle is flooded exists on the basis of travel resistance acquired on the basis of speed of the hybrid vehicle and acceleration of the hybrid vehicle and prohibits travel in the second mode if it is determined that there is the possibility that the exhaust pipe is flooded.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle that is capable of running with its internal combustion engine stopped. [Background technology]

[0002] Conventionally, there have been known control devices that prevent the exhaust pipe of a hybrid vehicle from becoming flooded when the hybrid vehicle runs through water (when the hybrid vehicle crosses a river, when the hybrid vehicle runs on a road where the water level has risen due to flooding, etc.). The exhaust pipe is a pipe for discharging exhaust gas generated by the internal combustion engine of the hybrid vehicle. For example, the control device described in Patent Document 1 (hereinafter referred to as the "conventional device") performs flood prevention control to prevent the exhaust pipe from becoming flooded when the following execution conditions are met. The flood prevention control is control to block the exhaust pipe or control to move the exhaust pipe to a position where flooding can be avoided.

[0003] The above execution conditions are met when the following conditions 1 to 3 are met. Condition 1: The internal combustion engine is stopped. Condition 2: The vehicle is running. Condition 3: It is determined that the water level has risen based on the humidity measured by a humidity sensor provided in the exhaust pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-156382 Summary of the Invention

[0005] Conventional devices require a humidity sensor to determine whether the execution conditions are met. In addition, a valve to close the exhaust pipe or a mechanism to move the exhaust pipe is required to prevent water from entering. For this reason, conventional devices are likely to have an increased number of parts.

[0006] The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is to provide a control device for a hybrid vehicle that can prevent water from entering the exhaust pipe without increasing the number of parts.

[0007] A hybrid vehicle (VA) controlled by the control device of the present invention (hereinafter referred to as the "device of the present invention") includes an internal combustion engine (30), a battery (38) for storing electric power, and an electric motor (34) for generating driving force using the electric power stored in the battery. the control device is capable of running the hybrid vehicle in a mode selected from a first mode in which the hybrid vehicle runs with the internal combustion engine operating, and a second mode in which the hybrid vehicle runs by the electric motor generating the driving force with the internal combustion engine stopped, Based on the speed (Vs) of the hybrid vehicle and the running resistance (RR) obtained based on the acceleration (G) of the hybrid vehicle, it is determined whether or not there is a possibility that the exhaust pipe of the hybrid vehicle will be flooded (step 310, step 325); When it is determined that there is a possibility that the exhaust pipe may be flooded (step 310 “Yes”; step 325 “Yes”), traveling in the second mode is prohibited (step 330); It is structured as follows.

[0008] According to the device of the present invention, whether or not there is a possibility of the exhaust pipe being flooded is determined based on the speed of the hybrid vehicle (hereinafter referred to as "vehicle speed") and the running resistance obtained based on the acceleration of the hybrid vehicle, so there is no need to provide a special sensor for this determination. Furthermore, according to the device of the present invention, if there is a possibility of the exhaust pipe being flooded, running in the second mode is prohibited, so the internal combustion engine does not stop (i.e., the internal combustion engine continues to operate). If the internal combustion engine is operating, exhaust gas is discharged from the exhaust pipe, so flooding of the exhaust pipe can be prevented. Therefore, according to the device of the present invention, flooding of the exhaust pipe can be prevented without increasing the number of parts. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic system configuration diagram of a control device for a hybrid vehicle according to an embodiment of the present invention; [Diagram 2] 1 is a graph showing the relationship between vehicle speed and running resistance. [Diagram 3] 2 is a flowchart of a water ingress prevention control routine executed by a CPU of the ECU shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A control device (hereinafter referred to as "this device") 10 according to this embodiment includes the components shown in FIG. 1, and is applied to a hybrid vehicle (hereinafter referred to as "vehicle") VA.

[0011] In this specification, "ECU 20" is an electronic control device having, as its main part, a microcomputer including a CPU (processor), ROM, RAM, an interface, and the like.

[0012] The ECU 20 is connected to a wheel speed sensor 22 and an acceleration sensor 24 . The wheel speed sensor 22 measures the rotation speed of the wheels of the vehicle VA. The acceleration sensor 24 measures the acceleration G in the longitudinal direction of the vehicle VA. The ECU 20 acquires the measured values ​​from these sensors 22 and 24. The ECU 20 acquires a vehicle speed Vs representing the speed of the vehicle VA based on the rotation speed of the wheels.

[0013] The ECU 20 is connected to a storage device 26. The storage device 26 has a non-volatile storage area. A current running resistance storage section 26a and a learned running resistance storage section 26b are set in the storage area.

[0014] The current running resistance memory unit 26a stores the running resistance RR for each vehicle speed Vs of the current trip. The learned running resistance memory unit 26b stores the running resistance RR for each vehicle speed Vs of past trips. A trip refers to the period from when the ignition key switch is changed from the OFF position to the ON position to when the ignition key switch is changed from the ON position to the OFF position. The current running resistance memory unit 26a and the learned running resistance memory unit 26b store the running resistance RR when the vehicle VA is not running through water.

[0015] The running resistance RR is the resistance that the vehicle VA encounters when it runs. In general, the running resistance RR is greater when the vehicle VA runs through water such as a "flooded road" or a "river" than when it runs normally. The ECU 20 obtains the running resistance RR by subtracting the actual acceleration G from the predicted acceleration Ge, which is determined according to the torque output by the drive source (the internal combustion engine 30 and / or the second electric motor 34).

[0016] The ECU 20 is connected to the internal combustion engine 30, a first electric motor 32, a second electric motor 34, and a battery 36. The power of the internal combustion engine 30 is transmitted to the left and right drive wheels Dw via a power distribution mechanism 38.

[0017] The power distribution mechanism 38 includes a known planetary gear mechanism. Details of the power distribution mechanism 38 are described in, for example, JP 2020-147130 A, and therefore will not be described here.

[0018] The first electric motor 32 and the second electric motor 34 are connected to a battery 36. The first electric motor 32 mainly functions as a generator for charging the battery 36. The second electric motor 34 mainly functions as a drive source that generates a drive force to be applied to the drive wheels Dw using the electric power charged in the battery 36.

[0019] The ECU 20 can run the vehicle VA in a mode selected from a first mode in which the vehicle VA runs with the internal combustion engine 30 operating, and a second mode in which the vehicle VA runs by driving the second electric motor 34 using the power charged in the battery 36 with the internal combustion engine 30 stopped.

[0020] As an example, when the charge amount of the battery 36 is equal to or less than a predetermined threshold amount, the ECU 20 runs the vehicle VA in a charge mode, which is one of the first modes. In the charge mode, the vehicle VA runs by the torque output by the internal combustion engine 30 while the first electric motor 32 is driven by the torque output by the internal combustion engine 30 that is in operation to charge the battery 36.

[0021] Furthermore, when the charge amount of the battery 36 is greater than the threshold amount and the requested driving force is equal to or less than the threshold driving force, the ECU 20 runs the vehicle VA in the second mode.

[0022] FIG. 2 shows an example of the relationship between vehicle speed Vs and running resistance RR. In detail, FIG. 2 shows running resistance RR1 when the vehicle VA is completely submerged, running resistance RR2 when it is submerged to 8% of the vehicle height, running resistance RR3 when climbing a slope / carrying / towing, and running resistance RR4 under normal conditions. As shown in FIG. 1, the water level when the vehicle is submerged to 8% of its height reaches near the bottom of the license plate. Therefore, when the vehicle is submerged to 8% of its height, there is a high possibility that the exhaust pipe will be submerged.

[0023] Since the density of water is greater than the density of air, the running resistance RR when the vehicle VA is running through water is greater than normal, as described above. Therefore, the running resistance RR1 is the largest, followed by the running resistance RR2, which is the next largest, and the running resistance RR3, which is the smallest, and the running resistance RR4 is the smallest.

[0024] When the vehicle speed Vs is equal to or lower than a predetermined vehicle speed Vs1, the running resistance R2 is smaller than the running resistance R3. Therefore, when the vehicle speed Vs is lower than a predetermined threshold vehicle speed (threshold speed) Vsth that is set to a value larger than the vehicle speed Vs1, the ECU 20 does not determine whether or not an execution condition described later is satisfied.

[0025] (Overview of operation) When both of the following conditions A1 and A2 are satisfied, the ECU 20 of the present device 10 determines that there is a possibility of flooding of the exhaust pipe and determines that the execution condition is satisfied. When the execution condition is satisfied, the ECU 20 prohibits the vehicle VA from traveling in the second mode.

[0026] Condition A1: The current vehicle speed Vs is equal to or greater than a threshold vehicle speed Vsth. Condition A2: A resistance difference ΔRR obtained by subtracting a running resistance RRa corresponding to the current vehicle speed Vs from the current running resistance RR is equal to or greater than a predetermined threshold difference ΔRRth. The threshold difference ΔRRth is set to a positive value.

[0027] When the running resistance RR of the current trip is stored in the current running resistance storage unit 26a, the ECU 20 acquires the running resistance RR corresponding to the current vehicle speed Vs from the current running resistance storage unit 26a as the running resistance RRa. On the other hand, when the running resistance RR of the current trip is not stored in the current running resistance storage unit 26a, the ECU 20 acquires the running resistance RR corresponding to the current vehicle speed Vs from the learned running resistance storage unit 26b as the running resistance RRa.

[0028] When the above execution condition is met, the vehicle VA is traveling through water and there is a high possibility that the exhaust pipe will be flooded. When this execution condition is met, the vehicle VA is prohibited from traveling in the second mode. Therefore, exhaust gas continues to be discharged from the exhaust pipe, preventing the exhaust pipe from being flooded.

[0029] To determine whether the above execution condition is satisfied, the vehicle speed Vs and the running resistance RR are required. The vehicle speed Vs and the running resistance RR are acquired based on the measurement value of the wheel speed sensor 22 and the measurement value of the acceleration sensor 24, respectively. In general, the wheel speed sensor 22 and the acceleration sensor 24 are provided in the vehicle VA, so there is no need to provide a special sensor. As a result, an increase in the number of parts can be prevented.

[0030] (Specific operation) The CPU of the ECU 20 (hereinafter referred to as the "CPU") executes a water ingress prevention control routine shown in the flowchart of FIG. 2 every time a predetermined time elapses.

[0031] When the appropriate time arrives, the CPU starts processing at step 300 in FIG.

[0032] Step 305: The CPU subtracts the actual acceleration G from the predicted acceleration Ge predicted based on the torque output by the drive source to obtain the running resistance RR. Step 310: The CPU determines whether the current vehicle speed Vs is equal to or greater than the threshold vehicle speed Vsth.

[0033] If the vehicle speed Vs is equal to or greater than the threshold vehicle speed Vsth, the CPU determines "Yes" in step 305 and proceeds to step 315. In step 315, the CPU determines whether or not the current running resistance storage unit 26a stores a running resistance RR for the vehicle speed Vs in a range sufficient for determining whether or not the execution condition is satisfied.

[0034] If the running resistance RR is stored in the current running resistance storage unit 26a, the CPU determines "Yes" in step 315 and executes steps 320 and 325.

[0035] Step 320: The CPU acquires the running resistance RRa corresponding to the current vehicle speed Vs from the current running resistance storage unit 26a. Step 325: The CPU determines whether or not the "resistance difference ΔRR obtained by subtracting the running resistance RRa from the current running resistance RR" is equal to or larger than the threshold difference ΔRRth.

[0036] If the resistance difference ΔRR is equal to or greater than the threshold difference ΔRRth, the exhaust pipe may be flooded, and the execution condition is met. In this case, the CPU determines "Yes" in step 325 and proceeds to step 330. In step 330, the CPU prohibits running in the second mode. After that, in step 395, the CPU temporarily ends this routine.

[0037] The execution condition is not met if the resistance difference ΔRR is less than the threshold difference ΔRRth when the process proceeds to step 325. In this case, the CPU determines “No” in step 325 and executes steps 335 and 340.

[0038] Step 335: The CPU stores the current vehicle speed Vs and the current running resistance RR in the current running resistance storage unit 26a. Step 340: The CPU permits running in the second mode. Thereafter, in step 395, the CPU temporarily ends this routine.

[0039] When the process proceeds to step 315, if the running resistance RR for a sufficient range of the vehicle speed Vs is not stored in the current running resistance storage unit 26a, the CPU determines "No" in step 315 and proceeds to step 345.

[0040] In step 345, the CPU acquires the running resistance RRa corresponding to the current vehicle speed Vs from the learned running resistance storage unit 26b. After that, the CPU advances the process to step 325.

[0041] If the vehicle speed Vs is less than the threshold vehicle speed Vsth when the process proceeds to step 310, the execution condition is not met. In this case, the CPU determines “No” in step 310 and executes steps 350 and 355.

[0042] Step 350: The CPU estimates the running state of the vehicle VA based on the most recent history of the vehicle speed Vs and the running resistance RR. For example, when the vehicle speed Vs is plotted on the horizontal axis and the running resistance RR is plotted on the vertical axis, if the history of the running resistance RR is parabolic, the CPU estimates that the vehicle VA is running through water. Step 355: The CPU determines whether the driving state is "a state in which the vehicle VA is driving through water."

[0043] If the running state is "a state in which the vehicle VA is running through water", the CPU determines "Yes" in step 355 and proceeds to step 330. In this case, since it is highly likely that the vehicle VA is running through water, the CPU does not store the current vehicle speed Vs and running resistance RR in the current running resistance storage unit 26a.

[0044] If the running state is not "a state in which the vehicle VA is running through water", the CPU determines "No" in step 355 and proceeds to step 335. In this case, since the vehicle VA is unlikely to be running through water, the CPU stores the current vehicle speed Vs and running resistance RR in the current running resistance storage unit 26a.

[0045] When the ignition key switch is changed from the ON position to the OFF position, the CPU updates the running resistance RR stored in the learned running resistance storage unit 26b based on the vehicle speed Vs and running resistance RR stored in the current running resistance storage unit 26a. Specifically, the CPU weights the running resistance RR of the past trip and the running resistance RR of the current trip for each vehicle speed Vs to obtain an average value, and stores the average value in the learned running resistance storage unit 26b. After that, the CPU erases the vehicle speed Vs and running resistance RR stored in the current running resistance storage unit 26a.

[0046] The CPU may determine that the execution condition is met when condition 3 is met instead of condition 2. Condition 3: The current running resistance RR is equal to or greater than a predetermined threshold resistance RRth. The threshold resistance RRth is set according to the vehicle speed Vs. For example, the threshold resistance RRt is set to the same value as the running resistance R2 shown in FIG. 2.

[0047] This embodiment is applicable to a hybrid vehicle VA that can run in a first mode and a second mode, and is not limited to the example shown in Fig. 1. When the acceleration G is obtained by differentiating the vehicle speed Vs with respect to time, the device 10 does not need to include the acceleration sensor 24. [Explanation of symbols]

[0048] 10... control device, 20... ECU, 22... wheel speed sensor, 24... acceleration sensor, 30... internal combustion engine, 32... first electric motor, 34... second electric motor, 36... battery, 38... power distribution mechanism.

Claims

[Claim 1] A control device for a hybrid vehicle including an internal combustion engine, a battery that stores electric power, and an electric motor that generates a driving force by using the electric power stored in the battery, The control device includes: The hybrid vehicle can be run in a mode selected from a first mode in which the hybrid vehicle runs with the internal combustion engine operating, and a second mode in which the hybrid vehicle runs by the electric motor generating the driving force with the internal combustion engine stopped, determining whether or not there is a possibility of flooding of an exhaust pipe of the hybrid vehicle based on a speed of the hybrid vehicle and a running resistance obtained based on an acceleration of the hybrid vehicle; prohibiting running in the second mode when it is determined that there is a possibility of flooding of the exhaust pipe; The control device for a hybrid vehicle is configured as described above.

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