Control device for hybrid vehicles and control method for hybrid vehicles

Abstract

The present invention provides a control device for hybrid vehicles that can suppress the emission of PM (particulate matter) outside the vehicle. [Solution] The hybrid vehicle comprises an engine 10, a motor 11, and a filter 14 that collects particulate matter emitted by the engine 10. The control device 15 controls the output of the engine 10 and the motor 11 according to the power required for the hybrid vehicle to run. After the engine 10 starts operating, the control device 15 limits the output of the engine 10 while the pores in the filter 14 are blocked with condensed water.

Description

Technical Field

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[0001] The present invention relates to a control device for a hybrid vehicle and a control method for a hybrid vehicle.

Background Art

[0002] In a so-called cold-started engine, the emission amount of particulate matter (PM) increases while the temperature is low. Patent Document 1 discloses a control device for a hybrid vehicle. This control device suppresses the output of the engine for a certain period of time from the start of the engine operation. And this control device compensates for the shortage of power required for running by a motor provided in the hybrid vehicle while the output of the engine is restricted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A filter for collecting PM is installed in the exhaust pipe of the engine. After the engine has a cold start, the condensed water generated by the condensation of the moisture contained in the exhaust may block the pores of the filter. In this case, since the passage amount of the exhaust in the pores of the filter that are not blocked by the condensed water increases, the collection rate of PM by the filter decreases.

Means for Solving the Problems

[0005] The control device for a hybrid vehicle that solves the above problems is applied to a hybrid vehicle comprising an engine, a motor, and a filter that collects particulate matter emitted by the engine. This control device for a hybrid vehicle controls the output of the engine and the motor according to the power required for the hybrid vehicle to run. After the engine starts operating, this control device for a hybrid vehicle limits the output of the engine while the pores in the filter are blocked with condensed water.

[0006] A control method for a hybrid vehicle that solves the above problems uses a control device for the hybrid vehicle. The control device is applied to a hybrid vehicle comprising an engine, a motor, and a filter for collecting particulate matter emitted by the engine. The control device controls the output of the engine and the motor according to the power required for the hybrid vehicle to run. This control method for a hybrid vehicle includes the step of the control device controlling the engine so that the output is less than or equal to a first upper limit value while the pores in the filter are blocked with condensed water after the engine has started to operate. This control method for a hybrid vehicle includes the step of the control device controlling the engine so that the output is less than or equal to a second upper limit value which is greater than the first upper limit value, until the engine has finished warming up, after the blockage of the pores in the filter by condensed water has been resolved. [Effects of the Invention]

[0007] The above-described control device and control method for the hybrid vehicle can suppress the emission of PM (particulate matter) outside the vehicle. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a hybrid vehicle equipped with a control device for one embodiment of the hybrid vehicle. [Figure 2] Figure 2 is a flowchart showing the sequence of processes performed by the control device in Figure 1. [Figure 3] Figure 3 is a time chart showing (a) the engine output controlled by the control device in Figure 1 and (b) the temperature of the filter. [Figure 4] Figure 4 is a flowchart showing the sequence of processes performed by the modified control unit. [Modes for carrying out the invention]

[0009] Below, one embodiment of the control device for a hybrid vehicle will be described with reference to Figures 1 to 3. <Configuration of 100 Hybrid Vehicles> As shown in Figure 1, the hybrid vehicle 100 is equipped with an engine 10. An exhaust pipe 12 is connected to the engine 10. The exhaust from the engine 10 is discharged outside the hybrid vehicle 100 through the inside of the exhaust pipe 12.

[0010] As shown in Figure 1, a three-way catalytic converter 13 is installed in the middle of the exhaust pipe 12. The three-way catalytic converter 13 uses a three-way catalyst to remove hydrocarbons and other components contained in the exhaust gas.

[0011] As shown in Figure 1, a filter 14 is installed downstream of the three-way catalytic converter 13 in the exhaust pipe 12. The filter 14 collects particulate matter (PM) contained in the exhaust. A three-way catalyst is supported on the filter 14. Therefore, like the three-way catalytic converter 13, the filter 14 can remove hydrocarbons and other components contained in the exhaust.

[0012] Thus, the exhaust from engine 10 is discharged outside the hybrid vehicle 100 after passing through the three-way catalytic converter 13 and the filter 14. As shown in Figure 1, the hybrid vehicle 100 is equipped with a motor 11. The motor 11 outputs the driving force of the hybrid vehicle 100.

[0013] As shown in Figure 1, the hybrid vehicle 100 is equipped with a control device 15. The control device 15 is the control device for the hybrid vehicle 100. The control device 15 is communicatively connected to the engine 10 and the motor 11. The control device 15 controls the output of the engine 10 and the motor 11 according to the power required for the hybrid vehicle 100 to run.

[0014] The control device 15 can change the ratio of the load on the engine 10 and the motor 11 for the power output necessary for driving the hybrid vehicle 100. For example, the control device 15 may request roughly equal output from the engine 10 and the motor 11. For example, the control device 15 may request more output from the engine 10 than from the motor 11. For example, the control device 15 may request more output from the motor 11 than from the engine 10.

[0015] Figure 2 shows the sequence of processes performed by the control device 15. After the engine 10 starts, the control device 15 performs the sequence of processes shown in Figure 2 at regular intervals.

[0016] In the series of processes shown in Figure 2, the control device 15 first executes the process in step S11. In the process in step S11, the control device 15 estimates the temperature of the filter 14. At this time, the control device 15 estimates the temperature of the filter 14 based on the temperature of the coolant in the engine 10 immediately after starting and the integrated value of the intake air volume in the hybrid vehicle 100.

[0017] The control device 15 stores a map indicating the temperature of the filter 14 corresponding to the combination of the temperature of the cooling water at the start of the engine 10 and the integrated value of the intake air amount in the hybrid vehicle 100. The control device 15 acquires information indicating the intake air amount from an air flow meter provided in the hybrid vehicle 100. The control device 15 acquires information indicating the temperature of the cooling water of the engine 10 from a sensor that measures the temperature of the cooling water of the engine 10. The control device 15 estimates the temperature of the filter 14 based on the values acquired from the air flow meter and the sensor and the stored map. After estimating the temperature of the filter 14, the control device 15 executes the process of step S12.

[0018] In the process of step S12, the control device 15 determines whether or not the estimated temperature of the filter 14 output in the process of step S11 is less than or equal to the first predetermined value A1. When the control device 15 determines in the process of step S12 that the estimated temperature is less than or equal to the first predetermined value A1 (step S12: YES), the process proceeds to step S14.

[0019] There is a case where the condensed water generated by the condensation of the moisture contained in the exhaust gas closes the pores of the filter 14. In this case, since the passage amount of the exhaust gas in the pores of the filter 14 that are not blocked by the condensed water increases, the PM collection rate by the filter 14 decreases.

[0020] When the temperature of the filter 14 is high, the condensed water evaporates, so the condensed water does not block the pores of the filter 14. On the other hand, when the temperature of the filter 14 is low, the condensed water is difficult to evaporate, so the condensed water blocks the pores of the filter 14.

[0021] When the estimated temperature is less than or equal to the first predetermined value A1, the control device 15 determines that the condensed water blocks the pores of the filter 14 without evaporating. Then, in the process of step S14, the control device 15 determines to limit the output of the engine 10 to be less than or equal to the first upper limit value P1. After that, the control device 15 ends the series of processes shown in FIG. 2.

[0022] Subsequently, the control device 15 controls the engine 10 so that its output is less than or equal to the first upper limit P1. In this case, for example, if the output of the engine 10 at or below the first upper limit P1 is insufficient to provide the power necessary for the hybrid vehicle 100 to run, the control device 15 compensates for the deficiency with the output of the motor 11. This output limitation continues until the control device 15 executes the series of processes shown in Figure 2 again.

[0023] If the control device 15 determines in step S12 that the estimated temperature is not less than or equal to the first default value A1 (step S12: NO), it proceeds to step S13. In other words, if the estimated temperature is greater than the first default value A1, the control device 15 proceeds to step S13.

[0024] In step S13, the control device 15 determines whether the estimated temperature of the filter 14 output in step S11 is less than or equal to the second default value A2. The second default value A2 is greater than the first default value A1. If the control device 15 determines in step S13 that the estimated temperature is less than or equal to the second default value A2 (step S13: YES), it proceeds to step S15.

[0025] Engine 10, when cold-started, will emit increased PM until it has warmed up. Furthermore, as mentioned earlier, while condensed water is blocking the pores of filter 14, PM is more easily discharged outside the vehicle.

[0026] The temperature of the engine 10 required to evaporate the condensate blocking the pores of the filter 14 is lower than the temperature at which the engine 10 is fully warmed up. Therefore, even when the temperature of the filter 14 reaches a level sufficient to evaporate the condensate, the engine 10 continues to discharge PM to the outside of the vehicle more easily than usual while it is not fully warmed up.

[0027] The control device 15 determines that the engine 10 has not warmed up if the estimated temperature is less than or equal to the second default value A2. Then, in the process of step S15, the control device 15 decides to limit the output of the engine 10 to less than or equal to the second upper limit value P2. After that, the control device 15 completes the series of processes shown in Figure 2.

[0028] Subsequently, the control device 15 controls the engine 10 so that its output is less than or equal to the second upper limit P2. The second upper limit P2 is greater than the first upper limit P1. In this case, for example, if the output of the engine 10 at or below the second upper limit P2 is insufficient to provide the power necessary for the hybrid vehicle 100 to run, the control device 15 compensates for the deficiency with the output of the motor 11. This output limitation continues until the control device 15 executes the series of processes shown in Figure 2 again.

[0029] If the control device 15 determines in step S13 that the estimated temperature is not less than or equal to the second default value A2 (step S13: NO), it proceeds to step S16. In other words, if the estimated temperature is greater than the second default value A2, the control device 15 proceeds to step S16.

[0030] In step S16, the control device 15 decides not to limit the output of the engine 10. Subsequently, the control device 15 completes the series of processes shown in Figure 2. From this point onward, the control device 15 controls the engine 10 without limiting its output.

[0031] After executing the process in step S16, the control device 15 does not execute the series of processes shown in Figure 2 until the engine 10 stops and then starts operating again. Alternatively, the control device 15 may execute the series of processes shown in Figure 2 again after a certain period of time has elapsed since executing the process in step S16.

[0032] <An example of the changes in engine 10 output and filter 14 temperature> Figure 3(a) shows an example of the power output changes of the engine 10 during a cold start. Figure 3(b) shows an example of the temperature changes of the filter 14 after the engine 10 has been cold-started, as estimated by the control device 15.

[0033] As shown in Figure 3(b), up to time T1, the estimated temperature of the filter 14 is less than or equal to the first default value A1. As previously mentioned, the control device 15 determines that condensate is blocking the pores of the filter 14 when the estimated temperature is less than or equal to the first default value A1. As shown in Figure 3(a), up to time T1, the output of the engine 10 has not exceeded the first upper limit value P1.

[0034] The lower the output of engine 10, the less PM is emitted from engine 10. After engine 10 starts operating, the control device 15 controls engine 10 so that its output is below a first upper limit P1 while the pores in filter 14 are blocked by condensate. In this way, the control device 15 can suppress the emission of PM to the outside of the vehicle when condensate is blocking the pores of filter 14.

[0035] As shown in Figure 3(b), during the period from time T1 to time T2, the estimated temperature of the filter 14 is greater than the first default value A1 and less than or equal to the second default value A2. The control device 15 determines that the blockage of the pores in the filter 14 by condensed water has been resolved when the estimated temperature of the filter 14 exceeds the first default value A1. Also, as mentioned above, the control device 15 determines that the engine 10 has not warmed up completely when the estimated temperature is less than or equal to the second default value A2. As shown in Figure 3(a), during the period from time T1 to time T2, the output of the engine 10 does not exceed the second upper limit value P2.

[0036] The control device 15 controls the engine 10 so that the output remains below the second upper limit P2 until the engine 10 has finished warming up, after the blockage of the pores in the filter 14 by condensed water has been resolved. This allows the control device 15 to suppress the emission of PM to the outside of the vehicle when the engine 10 has not finished warming up.

[0037] As shown in Figure 3(b), from time T2 onward, the estimated temperature of the filter 14 is greater than the second default value A2. The control device 15 determines that the engine 10 has finished warming up when the estimated temperature of the filter 14 becomes greater than the second default value A2. As shown in Figure 3(a), from time T2 onward, the output of the engine 10 is greater than the second upper limit value P2.

[0038] <Operation of this embodiment> The control device 15 reduces PM emissions from the engine 10 by limiting the output of the engine 10 while condensate is blocking the pores of the filter 14.

[0039] <Effects of this embodiment> (1) The control device 15 can suppress the emission of PM to the outside of the vehicle. (2) After the engine 10 starts operating, the control device 15 controls the engine 10 so that the output is less than or equal to a first upper limit P1 while the pores in the filter 14 are blocked with condensed water. After the blockage of the pores in the filter 14 by condensed water is resolved, the control device 15 controls the engine 10 so that the output is less than or equal to a second upper limit P2 which is greater than the first upper limit P1, until the engine 10 has finished warming up.

[0040] When engine 10 is cold-started, PM emissions increase while the temperature is low. While some of the pores in filter 14 are blocked by condensate, the PM collection efficiency of filter 14 decreases. Therefore, when condensate is blocking some of the pores, the amount of PM discharged outside the vehicle tends to increase compared to when condensate is not blocking some of the pores.

[0041] The temperature of the engine 10 required to evaporate the condensate blocking the pores of the filter 14 is lower than the temperature at which the engine 10 is fully warmed up. The control device 15 limits the output of the engine 10 by gradually easing the restriction amount in two stages: from the time the engine 10 starts operating until the condensed water in the filter 14 evaporates, and from the time the condensed water evaporates until the engine 10 has finished warming up. In other words, when the temperature of the engine 10 is low and PM is likely to be generated from the engine 10, the control device 15 continues to limit the output of the engine 10, but changes the degree of restriction depending on whether or not condensed water is present in the filter 14. When the pores of the filter 14 are blocked with condensed water and PM is likely to be discharged outside the vehicle, the control device 15 significantly limits the output of the engine 10, while easing the degree of restriction when the blockage of the pores by condensed water is resolved.

[0042] This prevents the control device 15 from limiting the output of the engine 10 more than necessary. (3) The control device 15 estimates the temperature of the filter 14 based on the intake air volume in the hybrid vehicle 100 and the temperature of the coolant in the engine 10. The control device 15 determines that the pores in the filter 14 are blocked by condensed water when the estimated temperature of the filter 14 is below a predetermined value.

[0043] When the temperature of filter 14 rises, condensed water evaporates. The control device 15 limits the output of engine 10 while the estimated temperature of filter 14 is low. Based on the estimated temperature of filter 14, the control device 15 can determine that condensed water is blocking the pores and limit the output of engine 10.

[0044] (4) The above-described control method for the hybrid vehicle 100 uses a control device 15. The control device 15 is applied to a hybrid vehicle 100 that includes an engine 10, a motor 11, and a filter 14 that collects particulate matter emitted by the engine 10. The control device 15 controls the output of the engine 10 and the motor 11 according to the power required for the hybrid vehicle 100 to run. The above-described control method for the hybrid vehicle 100 includes a step (step S14) in which the control device 15 controls the engine 10 so that the output is less than or equal to a first upper limit value P1 while the pores in the filter 14 are blocked with condensed water after the engine 10 has started to run. The above-described control method for the hybrid vehicle 100 includes a step (step S15) in which the control device 15 controls the engine 10 so that the output is less than or equal to a second upper limit value P2, which is greater than the first upper limit value P1, while the blockage of the pores in the filter 14 by condensed water is resolved and the engine 10 has finished warming up.

[0045] The control method for the hybrid vehicle 100 limits the output of the engine 10 by gradually easing the restriction amount in two stages: from the time the engine 10 starts operating until the condensed water in the filter 14 evaporates, and from the time the water evaporates until the engine 10 has finished warming up. As a result, the control method for the hybrid vehicle 100 can suppress the emission of PM to the outside of the vehicle.

[0046] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0047] The configuration of the hybrid vehicle 100 is not limited to the embodiment shown in Figure 1. For example, the hybrid vehicle 100 does not need to be equipped with a three-way catalytic converter 13. In the above embodiment, the control device 15 determines whether the engine 10 has finished warming up based on the estimated temperature of the filter 14. The manner in which the control device 15 determines whether the engine 10 has finished warming up is not limited to the above embodiment. For example, the control device 15 may determine that the engine 10 has finished warming up when a certain amount of time has elapsed since the engine 10 started operating.

[0048] In the above embodiment, the control device 15 estimates the temperature of the filter 14. Then, based on the estimated temperature of the filter 14, the control device 15 determines whether or not condensed water is blocking the pores in the filter 14. The manner in which the control device 15 determines whether or not condensed water is blocking the pores in the filter 14 is not limited to the above embodiment.

[0049] Figure 4 shows the sequence of processes performed by the modified control device 15. The modified control device 15 performs the sequence of processes shown in Figure 4 instead of the sequence of processes shown in Figure 2. The modified control device 15 performs the sequence of processes shown in Figure 4 at regular intervals after the engine 10 has started.

[0050] In the series of processes shown in Figure 4, the control device 15 first executes the process in step S21. In the process in step S21, the control device 15 determines whether a predetermined period has elapsed while the exhaust temperature of the engine 10 is above a predetermined value.

[0051] The exhaust gas passing through filter 14 causes the temperature of filter 14 to rise. Therefore, the control device 15 can determine that the temperature of filter 14 has risen to a level where condensed water can evaporate once exhaust gas at a sufficient temperature has passed through filter 14 for a sufficient period of time. In other words, the control device 15 can determine that condensed water is blocking the pores of filter 14 as long as the above conditions are not met.

[0052] The control device 15 obtains information indicating the exhaust temperature from, for example, a sensor installed in the exhaust pipe 12 that measures the exhaust temperature. Based on the information obtained from the sensor, the control device 15 determines whether a predetermined period of time has elapsed while the exhaust temperature of the engine 10 remains above a predetermined value.

[0053] If the control device 15 does not determine in step S21 that the exhaust temperature of the engine 10 has remained above a predetermined value for a predetermined period of time (step S21: NO), it proceeds to step S23.

[0054] The control device 15 determines that condensed water has not evaporated and is blocking the pores of the filter 14 until a predetermined period of time has elapsed while the exhaust temperature remains above a predetermined value after the engine 10 has started operating. Then, in the process of step S23, the control device 15 decides to limit the output of the engine 10 to a first upper limit value P1 or less. After that, the control device 15 completes the series of processes shown in Figure 4.

[0055] Subsequently, the control device 15 controls the engine 10 so that its output is less than or equal to the first upper limit P1. In this case, for example, if the output of the engine 10 at or below the first upper limit P1 is insufficient to provide the power necessary for the hybrid vehicle 100 to run, the control device 15 compensates for the deficiency with the output of the motor 11. This output limitation continues until the control device 15 executes the series of processes shown in Figure 4 again.

[0056] If the control device 15 determines in step S21 that a predetermined period has elapsed while the exhaust temperature of the engine 10 is above a predetermined value (step S21: YES), it proceeds to step S22.

[0057] In step S22, the control device 15 determines whether the engine 10 has finished warming up. The control device 15 estimates the temperature of the filter 14, for example, in the same manner as described in step S11 of Figure 2. Then, the control device 15 may determine that the engine 10 has finished warming up if the estimated temperature is greater than a predetermined value, in the same manner as described in step S13 of Figure 2. The control device 15 may also determine that the engine 10 has finished warming up when a certain amount of time has elapsed since the engine 10 started operating.

[0058] If the control device 15 determines in step S22 that the engine 10 has not warmed up (step S22: NO), it proceeds to step S24. In step S24, the control device 15 decides to limit the output of the engine 10 to the second upper limit P2 or less. After that, the control device 15 terminates the series of processes shown in Figure 4.

[0059] Subsequently, the control device 15 controls the engine 10 so that its output is less than or equal to the second upper limit P2. In this case, for example, if the output of the engine 10 at or below the second upper limit P2 is insufficient to provide the power necessary for the hybrid vehicle 100 to run, the control device 15 compensates for the deficiency with the output of the motor 11. This output limitation continues until the control device 15 executes the series of processes shown in Figure 4 again.

[0060] If the control device 15 determines in step S22 that the engine 10 has finished warming up (step S22: YES), it proceeds to step S25. In step S25, the control device 15 decides not to limit the output of the engine 10. Subsequently, the control device 15 completes the series of processes shown in Figure 4. From this point onward, the control device 15 controls the engine 10 without limiting its output.

[0061] After executing the process in step S25, the control device 15 does not execute the series of processes shown in Figure 4 until the engine 10 stops and then starts operating again. Alternatively, the control device 15 may execute the series of processes shown in Figure 4 again after a certain period of time has elapsed since the process in step S25.

[0062] In this case, the control device 15 determines that the pores in the filter 14 are blocked with condensed water from the time the engine 10 starts operating until a predetermined period of time has elapsed while the temperature of the exhaust gas from the engine 10 remains above a predetermined value.

[0063] When high-temperature exhaust gas passes through filter 14 for a certain period of time or longer, the condensed water blocking the pores of filter 14 evaporates. The control device 15 limits the output of engine 10 from the time engine 10 starts operating until it determines that the condensed water has evaporated due to the passage of exhaust gas. This allows the control device 15 to determine that condensed water is blocking the pores and limit the output of engine 10.

[0064] The control device 15 can also determine whether condensate is blocking the pores of the filter 14 by observing the pressure difference of the exhaust gas before and after the filter 14. If condensate is blocking the filter 14, the pressure difference of the exhaust gas before and after the filter 14 will increase. For example, the control device 15 may determine that condensate is blocking the pores of the filter 14 until a predetermined period of time has elapsed since the engine 10 started operating while the pressure difference of the exhaust gas before and after the filter 14 remains below a predetermined value.

[0065] The control device 15 controls the engine 10 so that the output remains below the second upper limit P2 until the engine 10 has finished warming up, after the blockage of the pores in the filter 14 due to condensate has been resolved. The control device 15 may also control the engine 10 without limiting the output even if the engine 10 has not finished warming up after the blockage of the pores in the filter 14 due to condensate has been resolved. [Explanation of symbols]

[0066] 10...Engine, 11...Motor, 12...Exhaust pipe, 13...Three-way catalytic converter, 14...Filter, 15...Control device, 100...Hybrid vehicle

Claims

1. This is a control device for a hybrid vehicle, which is applied to a hybrid vehicle comprising an engine, a motor, and a filter for collecting particulate matter emitted by the engine, and controls the output of the engine and the motor according to the power required for the hybrid vehicle to run. After the engine starts operating, the engine's output is limited while the pores in the filter are blocked with condensed water. Control system for hybrid vehicles.

2. After the engine has started operating, while the pores in the filter are blocked with condensed water, the engine is controlled so that the output is below a first upper limit. After the blockage of the pores in the filter due to condensed water is resolved, the engine is controlled so that its output is less than or equal to a second upper limit value which is greater than the first upper limit value, until the engine has finished warming up. A control device for a hybrid vehicle according to claim 1.

3. Based on the intake air volume in the hybrid vehicle and the temperature of the engine coolant, the temperature of the filter is estimated. When the estimated temperature of the filter is below a predetermined value, it is determined that the pores in the filter are blocked by condensed water. A control device for a hybrid vehicle according to claim 1 or claim 2.

4. From the time the engine starts operating until a predetermined period of time has elapsed while the temperature of the engine's exhaust remains above a predetermined value, it is determined that the pores in the filter are blocked by condensed water. A control device for a hybrid vehicle according to claim 1 or claim 2.

5. This method of controlling a hybrid vehicle is applied to a hybrid vehicle comprising an engine, a motor, and a filter for collecting particulate matter emitted by the engine, and uses a control device for the hybrid vehicle to control the output of the engine and the motor according to the power required for the hybrid vehicle to run. After the engine has started operating, the control device controls the engine so that the output is below a first upper limit while the pores in the filter are blocked with condensed water. The control device controls the engine so that the output is less than or equal to a second upper limit value which is greater than the first upper limit value, until the engine has warmed up, after the blockage of the pores in the filter by condensed water has been resolved. Control methods for hybrid vehicles.

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