Hybrid vehicle

Abstract

To provide a hybrid vehicle that is configured to promptly raise a temperature of a battery and a temperature of a catalyst under low temperature so as to be enabled to quickly run as usual.SOLUTION: The hybrid vehicle is provided with a driving motor 3 that drives a wheel 2; a battery 4 that outputs electricity to the driving motor 3; a heater 5 installed in combination on the battery 4; an engine 7 comprising a catalyst 6 that purifies exhaust gas; and a generator 8 installed in combination on the engine 7, which in a state where supply output from the battery 4 to the driving motor 3 is restricted and output for power generation from the engine 7 to the generator 8 is restricted accompanying temperature rise of the catalyst 6, under low temperature, controls output of the generator 8 so that the output is distributed into catalyst temperature-raise output for assisting rotation of the engine 7 to raise a temperature of the catalyst 6, battery temperature-raise output for distributing electricity to the heater 5 to raise a temperature of the battery 4 and torque-priority output for assisting driving force of the driving motor 3, according to a running state of a vehicle 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] In vehicles such as hybrid vehicles (HVs) and plug-in hybrid vehicles (PHEVs) that can be externally charged or powered, the battery's charge / discharge characteristics may deteriorate during cold start-up at low temperatures, resulting in an inability to meet the torque demands of the driver, resulting in a poor driving feel and a lack of battery charge.In addition, engine output may be limited because the catalyst that purifies the engine's exhaust gases is not heated sufficiently, which may prevent the generator attached to the engine from generating sufficient power.

[0003] To solve these problems at low temperatures, for example, Patent Document 1 below employs a configuration in which power is supplied from a battery to a heater during cold start, and the heater heats the battery.Also, for example, Patent Document 2 below employs a configuration in which the exhaust temperature is raised and the catalyst is heated by performing ultra-retarded combustion, in which the fuel injection timing and ignition timing are retarded from the compression top dead center. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-99418 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-31991 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Documents 1 and 2, configurations have already been proposed in which the temperature of each component, such as the battery or catalyst, is raised individually at low temperatures. However, in order to quickly complete the temperature rise of each component at low temperatures and enable normal driving, it is necessary to appropriately distribute the limited output of the battery and engine to each component, and with the configurations shown in Patent Documents 1 and 2 in which the temperature of each component is raised individually, it is difficult to enable normal driving early.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hybrid vehicle that can quickly increase the battery temperature and catalyst temperature at low temperatures, thereby enabling normal driving to begin sooner. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: The vehicle comprises a drive motor that drives wheels, a battery that outputs electric power to the drive motor, a heater attached to the battery, an engine equipped with a catalyst that purifies exhaust gas, and a generator attached to the engine, In a state where the output power supplied from the battery to the drive motor is limited at a low temperature and the power generation output from the engine to the generator is limited due to a rise in catalyst temperature, A hybrid vehicle (first configuration) is configured in which the output of the generator is controlled to be distributed among a catalyst heating output for assisting the rotation of the engine and heating the catalyst, a battery heating output for energizing the heater and heating the battery, and a torque priority output for assisting the driving force of the drive motor, depending on the running state of the vehicle.

[0008] In the first configuration, a first output threshold, which is a limited output power supplied from the battery to the drive motor at the low temperature, and a second output threshold, which is smaller than the first output threshold, are set; When the required output of the battery is less than the second output threshold, the output of the generator is distributed to the catalyst temperature increasing output; When the required output is equal to or greater than the second output threshold, the output of the generator is distributed to the battery warming output; When the required output is equal to or greater than the first output threshold, the output of the generator may be controlled to be distributed to the torque-priority output (second configuration).

[0009] In the second configuration, A third configuration (third configuration) may be employed in which control is performed such that the ratio of the torque-prioritized output to the battery temperature rise output gradually increases as the required output approaches the first output threshold from the second output threshold.

[0010] In the second or third configuration, The fourth configuration may be such that, when it is predicted that the frequency of regenerative running will be high based on route information of the route the vehicle is traveling, the second output threshold is controlled to be reduced by a first predetermined amount.

[0011] In the second or third configuration, The fifth configuration may include data relating to the temperature rise characteristics of the battery and the temperature rise characteristics of the catalyst in the area in which the vehicle travels, and if it is determined based on the data that the temperature rise of the catalyst can be completed in a shorter time than the temperature rise of the battery, the second output threshold is controlled to be increased by a second predetermined amount, while if it is determined that the temperature rise of the battery can be completed in a shorter time than the temperature rise of the catalyst, the second output threshold is controlled to be decreased by a third predetermined amount. [Effects of the Invention]

[0012] In this invention, when the output supplied from the battery to the drive motor is limited at low temperatures and the power generation output from the engine to the generator is limited due to catalyst temperature rise, the generator output is controlled to be distributed according to the vehicle's driving state among a catalyst heating output for assisting engine rotation and raising the catalyst temperature, a battery heating output for energizing the heater and raising the battery temperature, and a torque priority output for assisting the driving force of the drive motor, so that the battery temperature and catalyst temperature can be raised quickly at low temperatures and normal driving can be achieved early. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing an embodiment of a hybrid vehicle according to the present invention; [Figure 2] 2 is a block diagram showing a state in which generator output is distributed to catalyst temperature raising output in the hybrid vehicle shown in FIG. 1. FIG. [Figure 3] 2 is a block diagram showing a state in which generator output is distributed to battery temperature increasing output in the hybrid vehicle shown in FIG. 1. FIG. [Figure 4] 2 is a block diagram showing a state in which generator output is distributed to torque-prioritized output in the hybrid vehicle shown in FIG. 1. FIG. [Figure 5] FIG. 4 is a diagram showing the relationship between the vehicle speed, the torque required by the driver, and the output distribution of the generator. [Figure 6] 10 is a diagram showing the distribution ratio between the battery temperature increase output and the torque priority output when the required torque changes between a first output threshold and a second output threshold. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of a hybrid vehicle 1 (hereinafter referred to as vehicle 1 where appropriate) according to the present invention will be described with reference to the drawings. As shown in Fig. 1, vehicle 1 includes a drive motor 3 that drives wheels 2, a battery 4 that outputs electric power to drive motor 3, a heater 5 attached to battery 4, an engine 7 equipped with a catalyst 6 that purifies exhaust gas, and a generator 8 attached to engine 7. Vehicle 1 is a series hybrid vehicle 1 (HV) in which the generator 8 is driven by the output of engine 7, and electricity generated by generator 8 is used to charge battery 4 or to directly drive drive motor 3. Vehicle 1 includes all electric vehicles, such as plug-in hybrid vehicles (PHEVs) that can be externally charged or externally powered.

[0015] At low temperatures (for example, when the outside air temperature is below freezing), the charge / discharge characteristics of the battery 4 deteriorate, so the output of the battery 4 is limited to an output limit value, and the electricity generated by the generator 8 cannot be smoothly charged to the battery 4. As a result, the torque required by the driver cannot be satisfied, resulting in a poor driving feel and an insufficient charge level for the battery 4. Furthermore, at low temperatures, the catalyst 6, which purifies the exhaust gas from the engine 7, cannot fully function. As a result, engine output is limited to prioritize exhaust gas regulations, and it may be impossible to obtain a sufficient amount of power generation from the generator 8.

[0016] Therefore, in this vehicle 1, in order to quickly raise the battery temperature and catalyst temperature and quickly achieve normal driving, the output of the generator 8 is controlled to be appropriately distributed between a catalyst heating output for assisting the rotation of the engine 7 and raising the catalyst temperature, a battery heating output for energizing the heater 5 and raising the temperature of the battery 4, and a torque priority output for assisting the driving force of the drive motor 3, depending on the driving state of the vehicle 1.

[0017] In the control shown in Fig. 2 in which the generator output is distributed to the catalyst temperature raising output, most of the limited power output from the low-temperature battery 4 is sent to the generator 8 (generator power running), while the remaining power is sent to the drive motor 3. At this time, the engine 7 is subjected to super ignition retard, that is, control to retard the ignition timing from the compression top dead center.

[0018] In the super ignition retard state, much of the thermal energy generated by combustion is not converted into kinetic energy that moves the piston up and down, but is instead exhausted and used to heat the catalyst 6. For this reason, the rotation of the engine 7 is assisted by the generator 8, thereby stably driving the engine 7. Even when the driver is not stepping on the accelerator pedal (when the vehicle is stopped), the battery 4 outputs a weak electric power (lock current) to the drive motor 3, just enough to prevent the wheels 2 from rotating.

[0019] When the driver slightly depresses the accelerator pedal while the vehicle 1 is stopped, the output sent from the battery 4 to the drive motor 3 increases, and the vehicle 1 starts traveling at an extremely low speed (for example, 0 to 10 km / h). In this way, when the amount of depression of the accelerator pedal (torque required by the driver) is very small, the power required by the drive motor 3 is less than the output limit value of the battery 4 at low temperatures, so that the battery 4 can also supply power to the generator 8 (to assist the engine 7), and the temperature of the catalyst 6 continues to rise.

[0020] When the accelerator pedal is depressed further from a state in which the vehicle 1 is traveling at an extremely low speed, causing the vehicle 1 to travel at a low speed (for example, 10 to 20 km / h), and the required torque approaches the output limit value of the battery 4 at a low temperature, it is necessary to raise the temperature of the battery 4 and increase its output in order to satisfy the required torque.

[0021] Therefore, control is performed to distribute generator output to battery warming output, as shown in Figure 3. In this control, all of the limited power output from the low-temperature battery 4 is sent to the drive motor 3, while the generator 8 is driven by the limited output of the engine 7, which has not yet finished warming up the catalyst 6, and the electricity generated by the generator 8 heats the heater 5 to warm up the battery 4. At this time, the heat generated by the engine 7 continues to warm up the catalyst 6.

[0022] When the accelerator pedal is depressed to accelerate the vehicle 1 from a state in which the vehicle 1 is traveling at a low speed, the required torque exceeds the output limit value of the battery 4 at a low temperature, and the driver is unable to obtain the desired acceleration.

[0023] Therefore, control is performed to distribute the generator output to torque-prioritized output, as shown in Figure 4. In this control, all of the limited power output from the low-temperature battery 4 is sent to the drive motor 3, and the generator 8 is driven by the limited output of the engine 7, whose catalyst 6 has not yet finished heating, and all of the power generated by the generator 8 is sent to the drive motor 3. At this time, the catalyst 6 continues to heat up due to heat generated by the operation of the engine 7. It is preferable that the ratio of the amount of power sent to the drive motor 3 from the battery 4 and generator 8 to the side where warm-up operation is more advanced (the current temperature relative to the warm-up target temperature) is higher.

[0024] The distribution of the catalyst temperature rise output, battery temperature rise output, and torque priority output can be determined according to the driving conditions, such as the vehicle speed and the torque required by the driver. As an example, as shown in Fig. 5, the distribution can be controlled based on a map of the vehicle speed and the torque required by the driver when the temperature of the battery 4 is low. This map sets a first output threshold, which is a limited output (output limit value) supplied from the battery 4 to the drive motor 3 when the temperature is low, and a second output threshold that is smaller than the first output threshold.

[0025] The first output threshold is a threshold that is uniquely determined by the temperature of the battery 4, and is smaller as the temperature decreases and becomes larger as the temperature increases. In contrast, the second output threshold is a threshold that can be changed as appropriate depending on various conditions such as the driving environment of the vehicle 1. According to the control shown in FIG. 5, when the required output of the battery 4 is less than the second output threshold, the output of the generator 8 is allocated to catalyst temperature increase output. Furthermore, when the required output is equal to or greater than the second output threshold and less than the first output threshold, the output of the generator 8 is allocated to battery temperature increase output. Furthermore, when the required output is equal to or greater than the first output threshold, the output of the generator 8 is allocated to torque priority output.

[0026] In this map, the shaded area A indicates the torque that can be generated by the output of the battery 4, and the shaded area B indicates the torque that can be generated by the output of the generator 8. In a relatively low vehicle speed range (a speed range in which the output of the generator 8 is distributed to the catalyst temperature raising output or the battery temperature raising output), the output from the battery 4 is equal to or lower than the first output threshold, so the required torque can be met by the drive motor 3 alone. In contrast, in a relatively high vehicle speed range (a speed range in which the output of the generator 8 is distributed to the torque-priority output), the required torque cannot be met by the output from the battery 4 alone, so the drive of the drive motor 3 is assisted by the output of the generator 8.

[0027] In the above vehicle 1, when the output supplied from the battery 4 to the drive motor 3 is limited at low temperatures, and the power generation output from the engine 7 to the generator 8 is limited as the catalyst 6 temperature rises, the output of the generator 8 is controlled to be distributed among a catalyst heating output for assisting the rotation of the engine 7 and heating the catalyst 6, a battery heating output for energizing the heater 5 and heating the battery 4, and a torque priority output for assisting the driving force of the drive motor 3, depending on the driving state of the vehicle 1.As a result, the battery temperature and catalyst temperature can be quickly raised at low temperatures, and normal driving can be achieved early.

[0028] In particular, in the above vehicle 1, the distribution of the output of generator 8 is determined according to the required output of battery 4 and the magnitude relationship between the first output threshold and the second output threshold determined by the temperature of battery 4, so that the battery temperature and catalyst temperature can be quickly raised according to the driving state of vehicle 1 while achieving the driver's required torque.

[0029] As described above, the second output threshold is a threshold that serves as a criterion for determining whether the output of the generator 8 should be allocated to catalyst warming output or battery warming output. For example, if it is predicted that the frequency of regenerative driving will be high based on route information about the route traveled by the vehicle 1, the second output threshold can be controlled to be lowered by a first predetermined amount. By lowering the second output threshold in this manner, the vehicle speed at which the distribution is switched from catalyst warming output to battery warming output shifts toward lower vehicle speeds. This gives priority to raising the temperature of the battery 4 over that of the catalyst 6, thereby improving the acceptability of regenerative power during regenerative driving.

[0030] For example, if a destination is set in a navigation system before the vehicle 1 travels, the route information of the route includes various information such as elevation information and traffic congestion information along the route. Even if a destination is not set in the navigation system, if the vehicle has traveled the same route repeatedly in the past, route information equivalent to the navigation information may be obtained as a result of learning that accompanies the travel. It may also be possible to obtain route information by capturing information on various operations by the driver, such as the brake pedal, in real time.

[0031] In the above distribution control, the second output threshold value can also be changed based on data relating to the temperature rise characteristics of the battery 4 and the catalyst 6 in the area in which the vehicle 1 travels. For example, in a cold region where the temperature falls below 0°C in winter, data relating to the time it takes for the battery 4 to finish heating up and the time it takes for the catalyst 6 to finish heating up can be collected from multiple vehicles of the same model traveling in the same area, and a determination can be made as to whether the battery 4 or the catalyst 6 should be given priority in heating up in order to be able to start normal driving earlier when traveling in that area.

[0032] When it is determined that the temperature rise of the catalyst 6 can be completed in a shorter time than the temperature rise of the battery 4, the second output threshold is controlled to be increased by a second predetermined amount. Increasing the second output threshold in this manner shifts the vehicle speed at which the distribution is switched from catalyst temperature rise output to battery temperature rise output toward a higher vehicle speed. This gives priority to raising the temperature of the catalyst 6 over the temperature rise of the battery 4, allowing the drive of the generator 8 by the engine 7 to be brought into a normal operating state more quickly.

[0033] On the other hand, if it is determined that the temperature rise of the battery 4 can be completed in a shorter time than the temperature rise of the catalyst 6, the second output threshold is controlled to be lowered by a third predetermined amount. When the second output threshold is lowered in this way, the vehicle speed at which the distribution is switched from catalyst temperature rise output to battery temperature rise output shifts to the lower vehicle speed side. This gives priority to raising the temperature of the battery 4 over the temperature rise of the catalyst 6, and the output from the battery 4 to the drive motor 3 can be restored to normal operation more quickly.

[0034] Furthermore, during the distribution control, as shown in Fig. 6, it is also possible to control the ratio of torque-priority output to battery temperature rise output so as to gradually increase as the required output approaches the first output threshold from the second output threshold. If power is output from the battery 4 to the drive motor 3 before the battery 4 has finished rising in temperature, deterioration of the battery 4 may be accelerated. However, by gradually increasing the rate of assist from the generator 8, it is possible to both protect the battery 4 and raise its temperature. Note that while Fig. 6 illustrates an example of control in which the ratio of torque-priority output to battery temperature rise output changes linearly from point A to point B, it is also possible to control it so that it changes in a curved manner.

[0035] Furthermore, during the distribution control, the second output threshold value can be increased or decreased in consideration of the degree of deterioration of the battery 4. In this case, the degree of deterioration of the battery 4 can be estimated from the voltage value of the battery 4 and the value of the vehicle trip meter.

[0036] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0037] 1 Hybrid vehicle (vehicle) 2 wheels 3. Drive motor 4 Battery 5 Heater 6. Catalyst 7 Engine 8. Generator

Claims

1. The vehicle comprises a drive motor that drives wheels, a battery that outputs electric power to the drive motor, a heater attached to the battery, an engine equipped with a catalyst that purifies exhaust gas, and a generator attached to the engine, In a state where the output power supplied from the battery to the drive motor is limited at a low temperature and the power generation output from the engine to the generator is limited due to a rise in catalyst temperature, A hybrid vehicle in which the output of the generator is controlled to be distributed among a catalyst heating output for assisting the rotation of the engine and heating the catalyst, a battery heating output for energizing the heater and heating the battery, and a torque priority output for assisting the driving force of the drive motor, depending on the driving state of the vehicle.

2. a first output threshold value, which is a supply output from the battery to the drive motor that is limited at the low temperature, and a second output threshold value that is smaller than the first output threshold value are set; When the required output of the battery is less than the second output threshold, the output of the generator is distributed to the catalyst temperature raising output; When the required output is equal to or greater than the second output threshold, the output of the generator is distributed to the battery warming output; 2. The hybrid vehicle according to claim 1, wherein when the required output is equal to or greater than the first output threshold, the output of the generator is controlled to be distributed to the torque-prioritized output.

3. 3. The hybrid vehicle according to claim 2, wherein the ratio of the torque-prioritized output to the battery temperature rise output is controlled to gradually increase as the required output approaches the first output threshold from the second output threshold.

4. 3. The hybrid vehicle according to claim 2, wherein the second output threshold is controlled to be reduced by a first predetermined amount when it is predicted that regenerative running will be performed frequently based on route information about a route on which the vehicle is traveling.

5. 4. The hybrid vehicle according to claim 2 or 3, further comprising data relating to the temperature rise characteristics of the battery and the catalyst in an area in which the vehicle travels, and when it is determined based on the data that the temperature rise of the catalyst can be completed in a shorter time than the temperature rise of the battery, the second output threshold is controlled to be increased by a second predetermined amount, while when it is determined that the temperature rise of the battery can be completed in a shorter time than the temperature rise of the catalyst, the second output threshold is controlled to be decreased by a third predetermined amount.

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