Hybrid vehicles

Abstract

To provide a hybrid vehicle which secures an execution frequency of abnormality diagnosis of an engine.SOLUTION: A hybrid vehicle includes an engine, a motor and a control device for controlling the engine, wherein the control device includes: an intermittent operation control part for automatically stopping and automatically starting the engine during traveling by the motor; a feedback control part for performing feedback control on a control value of the engine so that an actual rotation speed of the engine becomes a target idle rotation speed, during idle operation of the engine; a calculation part for calculating a difference between the actual rotation speed and the target idle rotation speed, during execution of the feedback control; a determination part for determining whether or not the magnitude of the difference is larger than a first upper limit value within a range indicating that the engine is normal; a continuation part for continuing the operation of the engine regardless of presence / absence of the request of the automatic stop of the engine, when the determination part determines that it is positive; and a diagnosis part for executing abnormality diagnosis of the engine, after warm-up completion of the engine.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] During engine idling, a control value of the engine is feedback-controlled so that the actual engine speed becomes a target idle speed. After the engine has warmed up, an abnormality diagnosis of the engine is performed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-183653 Summary of the Invention [Problem to be solved by the invention]

[0004] In hybrid vehicles, intermittent operation is performed in which the engine is automatically stopped and started while the vehicle is running on the motor. If the engine is automatically stopped in this manner frequently, there is a risk that the frequency of abnormality diagnosis required by law, for example, cannot be ensured.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hybrid vehicle in which the frequency of engine abnormality diagnosis is ensured. [Means for solving the problem]

[0006] The above object can be achieved by a hybrid vehicle comprising an engine, a motor, and a control device that controls the engine, wherein the control device includes an intermittent operation control unit that automatically stops and starts the engine while the vehicle is running using the motor, a feedback control unit that feedback controls a control value of the engine while the engine is idling so that the actual rotation speed of the engine becomes a target idle rotation speed, a calculation unit that calculates the difference between the actual rotation speed and the target idle rotation speed while the feedback control is being performed, a determination unit that determines whether the magnitude of the difference is greater than a first upper limit value of a range in which the engine is normal, a continuation unit that continues operation of the engine regardless of whether there is a request to automatically stop the engine if the determination unit makes a positive determination, and a diagnosis unit that performs an abnormality diagnosis of the engine after the engine has finished warming up.

[0007] When the determination unit makes a negative determination and there is a request for automatic stopping of the engine, the intermittent operation control unit may automatically stop the engine.

[0008] The engine may further include a learning unit that learns the control value, and the diagnosing unit may diagnose an abnormality in the engine after warm-up of the engine is complete and after learning the control value.

[0009] The diagnosing unit may diagnose an abnormality of the engine based on whether the magnitude of the difference after the engine has been warmed up is greater than a second upper limit value of a range indicating that the engine is normal. [Effects of the Invention]

[0010] According to the present invention, a hybrid vehicle can be provided in which the frequency of execution of engine abnormality diagnosis is ensured. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 1 is a schematic configuration diagram of an engine. [Figure 3] 10 is a flowchart illustrating an example of an abnormality diagnosis process. [Figure 4] 10 is a flowchart illustrating details of an abnormality diagnosis. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Hybrid vehicle configuration] FIG. 1 is a schematic diagram of a hybrid vehicle 1 according to this embodiment. The hybrid vehicle 1 includes an ECU (Electronic Control Unit) 100, an engine 10, a first motor generator (hereinafter referred to as the "first MG (Motor Generator)") 14, a second motor generator (hereinafter referred to as the "second MG") 15, a PCU (Power Control Unit) 17, a battery 18, a power split mechanism 50, a transmission mechanism 51, a transmission 52, a drive shaft 53, a differential 54, and drive wheels 55. The engine 10 is a gasoline engine, but is not limited thereto and may be a diesel engine. The engine 10, the first MG 14, and the second MG 15 are power sources for driving the hybrid vehicle 1.

[0013] Each of the first MG 14 and the second MG 15 functions as a motor that outputs torque when supplied with electric power, and as a generator that generates regenerative power when torque is applied to it. The first MG 14 and the second MG 15 are electrically connected to a battery 18 via a PCU 17. The PCU 17 supplies electric power from the battery 18 to the first MG 14 or the second MG 15. The PCU 17 causes the battery 18 to receive the regenerative power generated in the first MG 14 or the second MG 15.

[0014] The power split mechanism 50 mechanically couples the crankshaft of the engine 10, the rotating shaft of the first MG 14, and the output shaft of the power split mechanism 50. The output shaft of the power split mechanism 50 is coupled to a transmission mechanism 51. The rotating shaft of the second MG 15 is coupled to the transmission mechanism 51. The transmission mechanism 51 is coupled to a transmission 52. The transmission 52 is coupled to a drive shaft 53. The driving forces of the engine 10, the first MG 14, and the second MG 15 are transmitted to drive wheels 55 via the transmission mechanism 51, the transmission 52, the drive shaft 53, and the differential 54. The transmission 52 is a stepped automatic transmission provided between the second MG 15 and the drive shaft 53.

[0015] The ECU 100 is an electronic control unit that includes a processing circuit that performs various types of calculations related to vehicle driving control and a memory that stores control programs and data. The ECU 100 is an example of a control device. The ECU 100 functionally realizes an intermittent operation control unit, a feedback control unit, a calculation unit, a determination unit, a continuation unit, a learning unit, and a diagnosis unit, which will be described later.

[0016] The ECU 100 receives signals from an ignition switch 71, a water temperature sensor 72, a crank angle sensor 73, and an air flow meter 74. The ignition switch 71 detects whether the ignition is on or off. The water temperature sensor 72 detects the temperature of the cooling water for the engine 10. The crank angle sensor 73 detects the engine rotation speed, which is the rotation speed of the crankshaft of the engine 10. The air flow meter 74 detects the amount of intake air introduced into the engine 10.

[0017] [Engine outline] FIG. 2 is a schematic diagram of the engine 10. The engine 10 includes a cylinder 30, a piston 31, a connecting rod 32, a crankshaft 33, an intake passage 35, an intake valve 36, an exhaust passage 37, and an exhaust valve 38. FIG. 2 illustrates one cylinder 30 of the multiple cylinders of the engine 10. An air-fuel mixture is combusted in the cylinder 30. A piston 31 is housed in the cylinder 30 so as to be able to reciprocate. The piston 31 is connected to the crankshaft 33 via a connecting rod 32. The connecting rod 32 converts the reciprocating motion of the piston 31 into the rotational motion of the crankshaft 33.

[0018] An in-cylinder injection valve 41d is provided in the cylinder 30. A port injection valve 41p is provided in the intake passage 35. An ignition device 42 that ignites an air-fuel mixture of intake air and fuel by spark discharge is provided in the cylinder 30.

[0019] The intake passage 35 is connected to an intake port 35p of the cylinder 30 via an intake valve 36. The exhaust passage 37 is connected to an exhaust port 37p of the cylinder 30 via an exhaust valve 38. The intake passage 35 is provided with the air flow meter 74 described above and a throttle valve 40 that controls the amount of intake air. The throttle valve 40 can increase or decrease the amount of intake air introduced into the cylinder 30. The exhaust passage 37 is provided with a catalyst 43 and a filter 44.

[0020] The ECU 100 automatically stops and starts the engine 10 while the hybrid vehicle 1 is running using the power of at least one of the first MG 14 and the second MG 15. For example, if the charge amount of the battery 18 becomes equal to or greater than a threshold while the hybrid vehicle 1 is running using the first MG 14 and the engine 10, the engine 10 is automatically stopped, and the hybrid vehicle 1 runs using the first MG 14. If the charge amount of the battery 18 becomes less than a threshold while the hybrid vehicle 1 is running using the first MG 14, the engine 10 is automatically started, and the hybrid vehicle 1 runs using the first MG 14 and the engine 10. In this way, the ECU 100 executes intermittent operation control to automatically stop and start the engine 10. The above control is an example of control executed by an intermittent operation control unit.

[0021] [Abnormality diagnosis processing] 3 is a flowchart illustrating the abnormality diagnosis process. This process is repeatedly executed at predetermined intervals while the ignition is on. The ECU 100 determines whether the engine 10 is idling (step S1). If the result in step S1 is No, this control ends.

[0022] If the answer is Yes in step S1, the ECU 100 determines whether the water temperature is higher than temperature T1 (step S2). Temperature T1 is set to an upper limit temperature at which feedback control, which will be described below, is stopped. Temperature T1 is also lower than the temperature that indicates that warming up of the engine 10 is complete. If the answer is No in step S2, this control ends. If the answer is Yes in step S2, the ECU 100 feedback-controls the control values ​​of the engine 10 so that the actual rotation speed of the engine 10 becomes the target idle rotation speed (step S3). The control values ​​include, for example, a control value for the fuel injection amount, a control value for the throttle opening, a control value for the air-fuel ratio, and a control value for the fuel ignition timing.

[0023] Next, the ECU 100 calculates the difference between the actual engine speed and the target idle speed of the engine 10 (step S4). Next, the ECU 100 determines whether the magnitude of the difference is greater than a first upper limit value D1 (step S5). The first upper limit value D1 is set to an upper limit value indicating that the engine 10 is normal before warm-up is complete. If the answer to step S5 is Yes, it is determined that there is a possibility that an abnormality has occurred in the engine 10. In this case, the ECU 100 executes a continuous operation control to continue the operation of the engine 10 (step S6). While the continuous operation control is being executed, the ECU 100 continues the operation of the engine 10 even if there is a request to automatically stop the engine 10. This promotes the warm-up of the engine 10 and prevents the engine 10 from automatically stopping before warm-up is complete. Note that if the answer to step S5 is No, the continuous operation control is not executed, and the ECU 100 automatically stops the engine 10 if there is a request to automatically stop the engine 10.

[0024] After step S6 is executed, or if step S5 is No, ECU 100 determines whether the water temperature is higher than temperature T2 (step S7). Temperature T2 is set to the lower limit temperature at which it is considered that the engine 10 has been warmed up. If step S7 is No, this control ends. If step S7 is Yes, ECU 100 determines whether the learning start condition is met (step S8). For example, if the engine 10 is running and a predetermined time has elapsed since the start of idling, the learning start condition is considered to be met. If step S8 is No, this control ends.

[0025] If the answer is Yes in step S8, the ECU 100 executes the learning of the control value described above (step S9). By executing the learning, the control value of the engine 10 is updated to the learned control value. Next, the ECU 100 executes an abnormality diagnosis of the engine 10 (step S10). Note that if the continuous operation control in step S6 is being executed, the ECU 100 stops the continuous operation control after the abnormality diagnosis is completed.

[0026] Next, the abnormality diagnosis will be described in detail. FIG. 4 is a flowchart illustrating the details of the abnormality diagnosis. The ECU 100 recalculates the difference between the actual rotation speed of the engine 10 and the target idle rotation speed (step S21). Next, the ECU 100 determines whether the magnitude of the difference is greater than a second upper limit value D2 (step S22). The second upper limit value D2 is set to the upper limit value of the range in which the engine 10 indicates normal operation after warm-up is complete. The second upper limit value D2 may be the same value as the first upper limit value D1, or may be a different value. If the answer to step S22 is No, the ECU 100 determines that the engine 10 is normal (step S23).

[0027] If the answer is Yes in step S22, the ECU 100 determines whether the learning update amount, which is the difference between the initial value of any of the above-mentioned control values ​​and the learning value of that control value, is greater than a threshold value P (step S24). The threshold value P is determined for each of the fuel injection amount, throttle opening, air-fuel ratio, and fuel ignition timing. The threshold value P is set to the upper limit of the normal range of the learning update amount. If the answer is No in step S24, this control ends. If the answer is Yes in step S24, the ECU 100 determines that the engine 10 is abnormal (step S25).

[0028] As described above, if the difference before the warm-up of the engine 10 is complete is greater than the first upper limit value D1, the operation of the engine 10 continues regardless of whether an automatic stop request is made. This prevents the engine 10 from automatically stopping before the warm-up is complete, ensuring the frequency with which abnormality diagnosis of the engine 10 is performed. This also prevents the engine 10 from automatically stopping while an abnormality diagnosis is being performed but before the diagnosis result is obtained.

[0029] If the difference before the warm-up of the engine 10 is complete is equal to or less than the first upper limit value D1 and an automatic stop request is made, the engine 10 is automatically stopped. As a result, if it is deemed unlikely that an abnormality has occurred in the engine 10, the engine 10 is automatically stopped, thereby ensuring fuel economy.

[0030] Furthermore, since the abnormality diagnosis is performed after the control value is learned, the abnormality diagnosis can be performed in a more stable operating state of the engine 10. This improves the accuracy of the abnormality diagnosis.

[0031] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0032] 1 Hybrid vehicle 10 Engine 14 First motor generator 100 ECU (controller, intermittent operation control unit, feedback control unit, calculation unit, judgment unit, continuation unit, learning unit, diagnosis unit)

Claims

1. The engine and A motor; a control device for controlling the engine, The control device an intermittent operation control unit that automatically stops and starts the engine while the vehicle is traveling using the motor; a feedback control unit that feedback-controls a control value of the engine so that an actual rotation speed of the engine becomes a target idle rotation speed while the engine is idling; a calculation unit that calculates a difference between the actual rotation speed and the target idle rotation speed during execution of the feedback control; a determination unit that determines whether the magnitude of the difference is greater than a first upper limit value of a range indicating that the engine is normal; a continuing unit that continues operation of the engine regardless of whether or not an automatic stop of the engine is requested when a positive determination is made by the determining unit; a diagnostic unit that executes an abnormality diagnosis on the engine after the engine has been warmed up.

2. 2. The hybrid vehicle according to claim 1, wherein when the determination unit makes a negative determination and there is a request for automatic stopping of the engine, the intermittent operation control unit automatically stops the engine.

3. a learning unit that learns the control value, 3. The hybrid vehicle according to claim 1, wherein the diagnosing unit executes an abnormality diagnosis for the engine after the engine has been warmed up and after the control value has been learned.

4. 3. The hybrid vehicle of claim 1, wherein the diagnosing unit diagnoses an abnormality of the engine based on whether the magnitude of the difference after the engine has been warmed up is greater than a second upper limit value of a range indicating that the engine is normal.

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