Vehicle

Abstract

To provide a vehicle capable of preventing an excessive temperature rise and clogging of a filter.SOLUTION: A vehicle includes: an engine as a traveling driving source; a filter that collects exhaust gas particulate matters from the engine; a sensor that detects a correlation value correlated with friction torque of the engine; and a control device that executes temperature rise control for raising a temperature of exhaust gas of the engine by controlling the engine and thus raising a temperature of the filter. The control device increases a temperature rise rate of the exhaust gas through the temperature rise control as the friction torque indicated by the correlation value is lower.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a vehicle.

Background Art

[0002] In order to prevent clogging of the filter, temperature increase control is performed to raise the temperature of the filter and burn the exhaust particulates collected by the filter (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] From cold start to warm-up completion, the temperature of the engine lubricating oil gradually rises, and accordingly, the engine friction torque gradually decreases. As a result, for example, when the vehicle speed is constant, the accelerator opening operated by the driver gradually decreases as the friction torque decreases. As a result, the temperature of the engine exhaust gas gradually decreases. If the temperature increase control is performed without considering such a decrease in friction torque, there is a risk that the filter may overheat or the filter may not be heated sufficiently to prevent clogging of the filter.

[0005] Therefore, an object of the present invention is to provide a vehicle capable of preventing overheating and clogging of the filter.

Means for Solving the Problems

[0006] The above object can be achieved by a vehicle including: an engine as a driving power source; a filter that collects exhaust particles from the engine; a sensor that detects a correlation value correlated with the friction torque of the engine; and a control device that executes a temperature increase control for increasing the temperature of the exhaust gas of the engine to increase the temperature of the filter by controlling the engine. The lower the friction torque indicated by the correlation value is, the greater the temperature increase rate of the exhaust gas by the temperature increase control is increased by the control device.

[0007] The correlation value may be the temperature of lubricating oil that lubricates the engine or the temperature of cooling water that cools the engine.

[0008] The control device may increase the temperature increase rate by the temperature increase control by controlling the ignition timing of the engine to the retard side.

[0009] The control device may increase the temperature increase rate by the temperature increase control by at least one of reducing the EGR rate, increasing the difference in air-fuel ratio by dither control, and increasing the required charge rate per unit time of a battery that is charged with electric power generated by the power of the engine.

[0010] The vehicle may include a motor as a driving power source and a battery that exchanges electric power with the motor.

Advantages of the Invention

[0011] According to the present invention, a vehicle capable of preventing overheating and clogging of the filter can be provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0013] [Schematic Configuration of Hybrid Vehicle] FIG. 1 is a schematic configuration diagram of a hybrid vehicle 1. The hybrid vehicle 1 is equipped with an engine 10 and a motor 15 as driving power sources. The engine 10 is a gasoline engine having a plurality of cylinders, but it may also be a diesel engine. A transmission unit 11 is provided on the power transmission path from the engine 10 to the drive wheels 13. The transmission unit 11 and the left and right drive wheels 13 are drivingly connected via a differential 12.

[0014] The transmission unit 11 is provided with a K0 clutch 14 and a motor 15. The motor 15 is provided on the power transmission path from the engine 10 to the drive wheels 13.

[0015] The K0 clutch 14 is provided between the engine 10 and the motor 15 in the same power transmission path. The K0 clutch 14 is engaged upon receiving the supply of hydraulic pressure to connect the power transmission between the engine 10 and the motor 15. The K0 clutch 14 becomes disengaged in response to the stop of the hydraulic pressure supply.

[0016] The motor 15 is connected to the battery 16 via the inverter 17. The battery 16 is a rechargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The motor 15 functions as a motor that generates the driving force of the vehicle in response to the power supply from the battery 16. Further, the motor 15 also functions as a generator that generates electric power for charging the battery 16 in response to the power transmission from the engine 10 or the drive wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0017] The transmission unit 11 is provided with a torque converter 18 and an automatic transmission 19. The torque converter 18 is a fluid coupling having a torque amplification function. The automatic transmission 19 is a stepped transmission that switches the gear ratio in multiple steps. The torque converter 18 is provided between the motor 15 and the drive wheels 13 on the above power transmission path. The automatic transmission 19 is provided between the torque converter 18 and the drive wheels 13 on the above power transmission path. The torque converter 18 is provided with a lock-up clutch (hereinafter referred to as the LU clutch) 20 that engages upon receiving the supply of hydraulic pressure to directly connect the motor 15 and the automatic transmission 19.

[0018] The LU clutch 20 is engaged upon receiving the supply of hydraulic pressure to connect the power transmission between the motor 15 and the drive wheels 13. The LU clutch 20 becomes disengaged in response to the stop of the hydraulic pressure supply.

[0019] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the LU clutch 20 via the hydraulic control mechanism 22, respectively. The hydraulic control mechanism 22 is provided with respective hydraulic circuits for the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the LU clutch 20, and various hydraulic control valves for controlling their operating hydraulic pressures.

[0020] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 50 as a control device for the vehicle. The ECU 50 is an electronic control unit including an arithmetic processing circuit that performs various arithmetic processes related to the running control of the vehicle, and a memory in which control programs and data are stored. The ECU 50 is an example of a control device for the hybrid vehicle 1, and specifically executes warm-up control which will be described later.

[0021] An ignition switch 61, a crank angle sensor 62, an air flow meter 63, an air-fuel ratio sensor 64, an oil temperature sensor 65, and a water temperature sensor 66 are connected to the ECU 50. The ignition switch 61 detects the on / off of the ignition. The crank angle sensor 62 detects the rotational speed of the crankshaft of the engine 10. The air flow meter 63 detects the intake air amount introduced into the engine 10. The air-fuel ratio sensor 64 detects the air-fuel ratio of the exhaust of the engine 10. The oil temperature sensor 65 detects the temperature of the lubricating oil of the engine 10. The water temperature sensor 66 detects the temperature of the cooling water for cooling the engine 10.

[0022] The ECU 50 controls the driving of the engine 10 and the motor 15. Specifically, the ECU 50 controls the inverter 17 to adjust the amount of power transfer between the motor 15 and the battery 16, thereby performing torque control of the motor 15. The ECU 50 performs driving control of the K0 clutch 14, the LU clutch 20, and the automatic transmission 19 through the control of the hydraulic control mechanism 22.

[0023] The ECU 50 drives the hybrid vehicle 1 in either the motor driving mode or the hybrid driving mode. In the motor driving mode, the ECU 50 disengages the K0 clutch 14 and rotates the drive wheels 13 with the power of the motor 15. In the hybrid driving mode, the ECU 50 engages the K0 clutch 14 and rotates the drive wheels 13 with the power of at least one of the engine 10 and the motor 15.

[0024] [Schematic Configuration of Engine] Figure 2 is a schematic configuration diagram of the engine 10. The engine 10 has a cylinder block 30, a cylinder head 32, a piston 33, a connecting rod 34, a crankshaft 35, an intake passage 36, an intake valve 36v, an exhaust passage 37, and an exhaust valve 37v.

[0025] The cylinder block 30 is provided with a cylindrical bore 31. The piston 33 is reciprocally accommodated within the bore 31. The combustion chamber C is defined by the wall surface of the bore 31, the lower surface of the cylinder head 32, and the top surface of the piston 33. The volume of the combustion chamber C increases and decreases with the reciprocating motion of the piston 33.

[0026] The crankshaft 35, which is the output shaft of the engine 10, is connected via the connecting rod 34. The connecting rod 34 and the crankshaft 35 convert the reciprocating motion of the piston 33 into the rotational motion of the crankshaft 35. The engine 10 is provided with the above-described crank angle sensor 62.

[0027] The intake passage 36 is connected to the combustion chamber C via the intake valve 36v. The exhaust passage 37 is connected to the combustion chamber C via the exhaust valve 37v. The above-described air flow meter 63 is provided in the intake passage 36.

[0028] The cylinder block 30 is provided with an in-cylinder injection valve 41D that directly injects fuel into the combustion chamber C. The intake passage 36 is provided with a port injection valve 41P that injects fuel toward the intake port. The cylinder head 32 is provided with a spark plug 42 that ignites the air-fuel mixture introduced into the combustion chamber C. Note that only one of the in-cylinder injection valve 41D and the port injection valve 41P may be provided.

[0029] The exhaust passage 37 is provided with a three-way catalyst 43 and a GPF (Gasoline Particulate Filter) 44. The three-way catalyst 43 contains a catalyst metal, has an oxygen storage capacity, and purifies NOx, HC, and CO. The GPF 44 is a porous ceramic structure that collects exhaust particulate matter (hereinafter referred to as PM (Particulate Matter)) in the exhaust gas. The GPF 44 is an example of a filter. Note that, for example, when the engine 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF 44. An air-fuel ratio sensor 64 is provided between the three-way catalyst 43 and the GPF 44. The air-fuel ratio sensor 64 detects the air-fuel ratio of the exhaust gas discharged from the three-way catalyst 43.

[0030] Based on the detection signals of the above-described sensors, the ECU 50 controls the driving of the engine 10 by controlling the opening degree of the throttle valve 40, the fuel injection amount of the in-cylinder injection valve 41D and the port injection valve 41P, the ignition timing by the spark plug 42, and the like.

[0031] When a predetermined condition is satisfied in the hybrid driving mode, the ECU 50 executes a temperature-raising control for raising the temperature of the GPF 44. The temperature-raising control is performed to promote the combustion of the PM deposited on the GPF 44. The predetermined condition is that the deposition amount of PM on the GPF 44 is equal to or greater than a predetermined value. The deposition amount of PM may be estimated based on, for example, the driving history of the engine 10 since the completion of the previous temperature-raising control, the differential pressure before and after the GPF 44, or the like, or may be estimated by other known methods. The temperature-raising control will be described below.

[0032] [Warming control] In this embodiment, warming control is executed by retarding the ignition timing, which controls the ignition timing to the retarded side from the basic ignition timing. By retarding the ignition timing, the amount of heat in the exhaust gas increases, and the GPF 44 can be warmed up. Thereby, the PM deposited on the GPF 44 can be burned.

[0033] However, there is a possibility that the following problems may occur from the cold start of the engine 10 until the warm-up is completed. FIG. 3A is a time chart showing the transition of the temperature increase rate of the exhaust gas due to the decrease in the friction torque from the cold start to the completion of the warm-up. FIG. 3B is a time chart showing the transition of the temperature increase rate of the exhaust gas by the warming control in the comparative example. FIG. 3C is a time chart showing the transition of the temperature of the GPF 44 due to the decrease in the friction torque and the warming control in the comparative example. FIGS. 3A to 3C show an example in the case of traveling at a constant vehicle speed. The temperature increase rate in FIG. 3A indicates the temperature increase rate of the exhaust gas due to the friction torque when the temperature of the exhaust gas at the completion of the warm-up in the state where the warming control is not executed is used as a reference. The temperature increase rate in FIG. 3B indicates the temperature increase rate of the exhaust gas by the warming control when the temperature of the exhaust gas at the completion of the warm-up in the state where the warming control is not executed is used as a reference. The friction torque is a frictional torque that resists the rotation of the engine 10.

[0034] From the cold start to the completion of the warm-up, the temperature of the lubricating oil of the engine 10 gradually rises, and the friction torque of the engine 10 gradually decreases. Here, when the vehicle speed is maintained constant, the accelerator opening decreases as the friction torque decreases. As the accelerator opening decreases, the temperature of the exhaust gas also decreases. Therefore, from the cold start to the completion of the warm-up, as shown in FIG. 3A, the temperature increase rate of the exhaust gas gradually decreases due to the decrease in the friction torque. When a constant warming control is executed under such a situation where the temperature increase rate of the exhaust gas is constant, as shown in FIG. 3C, the temperature of the GPF 44 decreases from a temperature higher than the target temperature to a lower temperature. For this reason, the GPF 44 may be overheated, and thereafter, the temperature rise of the GPF 44 may be insufficient and it may not be possible to prevent clogging.

[0035] FIG. 4A is a time chart showing the transition of the exhaust gas temperature increase rate due to the decrease in friction torque from cold start to warm-up completion. FIG. 4B is a time chart showing the transition of the exhaust gas temperature increase rate by the temperature increase control in this embodiment. FIG. 4C is a time chart showing the transition of the temperature of the GPF 44 due to the decrease in friction torque and the temperature increase control in this embodiment. Note that FIG. 4A is the same as FIG. 3A, and FIGS. 4B and 4C correspond to FIGS. 3B and 3C, respectively. In the temperature increase control executed by the ECU 50 in this embodiment, the exhaust gas temperature increase rate by the temperature increase control gradually increases so as to offset the decrease in the exhaust gas temperature increase rate due to the decrease in friction torque. Thereby, the temperature of the GPF 44 is maintained at the target temperature. The ECU 50 of this embodiment specifically executes the temperature increase control as follows.

[0036] FIG. 5 is a flowchart illustrating the temperature increase control executed by the ECU 50 in this embodiment. This control is repeatedly executed while the ignition is on. The ECU 50 detects the temperature of the lubricating oil of the engine 10 based on the oil temperature sensor 65 (step S1). The temperature of the lubricating oil is an example of a correlation value correlated with the friction torque of the engine 10. This is because the higher the temperature of the lubricating oil, the lower the viscosity of the lubricating oil, and the lower the friction torque of the engine 10.

[0037] Next, the ECU 50 sets the target ignition timing based on the temperature of the lubricating oil (step S2). FIG. 6 is an exemplary diagram of a map defining the target ignition timing according to the temperature of the lubricating oil in the temperature increase control. As shown in FIG. 6, the higher the temperature of the lubricating oil, the more the target ignition timing is set on the retard side. Thereby, as the temperature of the lubricating oil increases and the friction torque of the engine 10 decreases, the exhaust gas temperature increase rate by the temperature increase control increases. Note that FIG. 6 shows the target ignition timing when the engine speed and the engine torque are constant. The higher the engine speed and the greater the engine torque, the more the target ignition timing is set on the advance side.

[0038] Next, the ECU 50 executes warm-up control by controlling the ignition timing to the calculated target ignition timing (step S3). As a result, as shown in FIG. 4C, overheating of the GPF 44 and clogging of the GPF 44 can be suppressed.

[0039] In the above embodiment, control for adjusting the ignition timing was described as an example of warm-up control, but the warm-up control is not limited to this. For example, when the engine has an EGR (Exhaust Gas Recirculation) device, warm-up control may be realized by adjusting the EGR rate. The EGR rate is the ratio of the amount of EGR gas in the intake gas supplied to the engine 10. The lower the EGR rate, the greater the pumping loss, and the higher the temperature of the exhaust gas. Therefore, by decreasing the EGR rate as the temperature of the lubricating oil increases, the rate of increase in the temperature of the exhaust gas due to warm-up control can be increased.

[0040] Also, warm-up control may be realized by adjusting the difference in the air-fuel ratio in the dither control. The dither control is control in which at least one of a plurality of cylinders of the engine 10 has a lean air-fuel ratio and the rest have a rich air-fuel ratio. In this case, the higher the difference between the lean air-fuel ratio and the rich air-fuel ratio, the higher the temperature of the exhaust gas supplied to the GPF 44. Therefore, by increasing the difference in the air-fuel ratio as the temperature of the lubricating oil increases, the rate of increase in the temperature of the exhaust gas due to warm-up control can be increased.

[0041] Also, warm-up control may be realized by adjusting the required charging rate per unit time of the battery 16. The motor 15 generates electricity receiving the power of the engine 10, and this generated power is charged to the battery 16. Therefore, the higher the required charging rate per unit time of the battery 16, the higher the temperature of the exhaust gas. Therefore, by increasing the required charging rate per unit time as the temperature of the lubricating oil increases, the rate of increase in the temperature of the exhaust gas due to warm-up control can be increased.

[0042] Further, the temperature increase control may be realized by executing a plurality of the above-described adjustments of the ignition timing, the EGR rate, the difference in the air-fuel ratio in the dither control, and the required charge rate of the battery 16.

[0043] In the above embodiment, the temperature of the lubricating oil is used as the correlation value. However, for example, in a vehicle not equipped with an oil temperature sensor, the temperature of the cooling water detected by the water temperature sensor may be used as the correlation value. This is because the higher the temperature of the cooling water, the higher the temperature of the engine 10, and the higher the temperature of the engine 10, the higher the temperature of the lubricating oil.

[0044] As described above, the hybrid vehicle 1 includes a motor 15 and a battery 16 in addition to the engine 10. For example, the battery 16 supplies power to the motor 15, which is a driving power source, and charges the regenerative power of the motor 15. Therefore, the battery 16 is heavier than the battery mounted on an engine vehicle. Thus, the weight of the hybrid vehicle 1 is greater compared to an engine vehicle. As a result, the load on the engine 10 in the hybrid driving mode is greater compared to the engine of an engine vehicle. For this reason, the amount of PM emissions in the hybrid driving mode may increase compared to an engine vehicle. Therefore, the content of the above embodiment is suitable for the hybrid vehicle 1.

[0045] The content of the above embodiment may also be applied to a control device for an engine vehicle having only an engine as a driving power source. The content of the above embodiment may also be applied to a control device for a hybrid vehicle in which an engine and a first motor are connected to a drive shaft connected to drive wheels via a planetary gear and a second motor is connected to the drive shaft.

[0046] As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0047] 1 Hybrid vehicle 10 Engine 15 Motor 16 Battery 44 GPF (Filter) 50 ECU (Control Device) 65 Oil Temperature Sensor (Sensor) 66 Water Temperature Sensor (Sensor)

Claims

1. An engine that is a driving power source, A filter that collects exhaust particles from the engine, A sensor that detects a correlation value correlated with the friction torque of the engine, A control device that executes temperature increase control to increase the temperature of the exhaust gas of the engine to increase the temperature of the filter by controlling the engine, and A vehicle in which the lower the friction torque indicated by the correlation value, the greater the rate of temperature increase of the exhaust gas by the temperature increase control by the control device.

2. The vehicle according to claim 1, wherein the correlation value is the temperature of lubricating oil that lubricates the engine or the temperature of cooling water that cools the engine.

3. The vehicle according to claim 1 or 2, wherein the control device increases the rate of temperature increase by the temperature increase control by controlling the ignition timing of the engine to the retard side.

4. The vehicle according to claim 1 or 2, wherein the control device increases the rate of temperature increase by the temperature increase control by at least one of reducing the EGR rate, increasing the difference in air-fuel ratio by dither control, and increasing the required charge rate per unit time of a battery that is charged with electric power generated by the power of the engine.

5. A motor that is a driving power source, A battery that exchanges electric power with the motor, and The vehicle according to claim 1 or 2, comprising.

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