Vehicle control device

Abstract

To provide a controller of a vehicle which can suppress frequency of engine torque and resonance frequency of a torsional system from coming close to each other without changing operation point of an engine during warming-up control of a catalyst device.SOLUTION: A controller of a vehicle comprises: an engine; a catalyst device which purifies exhaust gas of the engine; a transmission mechanism which can change transmission gear ratio between the engine and drive wheels; and a damper mechanism which is arranged between the engine and the transmission mechanism to attenuate pulse of torque of the engine. The transmission mechanism includes an engagement mechanism which can change torque capacity transmitted from the engine. When the vehicle stops and when the engine is operated at a specific operation point to warm up the catalyst device (Yes of steps S1, S2), transmission torque capacity of the engagement mechanism is set to be a prescribed capacity or less (step S3).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle equipped with an engine, a damper mechanism, and a transmission mechanism having an engagement mechanism. [Background technology]

[0002] Patent Document 1 describes a control device that, when continuous rattle noise of a planetary gear connected to an engine is detected while executing ignition retard control to warm up a catalytic converter that purifies the engine's exhaust, changes the engine's operating point to suppress the rattle noise. Specifically, when rattle noise is detected while executing ignition retard control, the control device first reduces the engine torque below a torque that improves fuel efficiency. If the rattle noise continues even after reducing the engine torque, the control device increases or decreases the engine speed to a speed outside the resonant speed range where resonance occurs in the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-83409 Summary of the Invention [Problem to be solved by the invention]

[0004] The control device described in Patent Document 1 changes the engine operating point to suppress rattle noise while continuing to execute ignition retard control to warm up the catalytic converter. However, since the engine operating point during catalyst warm-up is determined taking into consideration various conditions such as minimum engine speed, warm-up performance, and vibration suppression, changing the engine operating point to suppress rattle noise could result in any of the above conditions not being met, potentially resulting in new inconveniences.

[0005] The present invention has been made with a focus on the above-mentioned technical problems, and aims to provide a vehicle control device that can prevent the engine torque frequency and the resonant frequency of the torsional system from becoming close to each other without changing the operating point of the engine during warm-up control of the catalytic converter. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a control device for a vehicle including an engine, a catalytic converter that purifies exhaust gas from the engine, a transmission mechanism that can change the speed ratio between the engine and drive wheels, and a damper mechanism that attenuates torque pulsation of the engine between the engine and the transmission mechanism, wherein the transmission mechanism includes an engagement mechanism that can change the torque capacity transmitted between the engine and the transmission mechanism, and when the vehicle is stopped and the engine is operating at a predetermined operating point to warm up the catalytic converter, the transmission torque capacity of the engagement mechanism is the vehicle is stopped and the catalytic converter is not warmed up, the torque transmission capacity is less than a predetermined torque transmission capacity. It is characterized by setting 。 In addition, in the present invention, the transmission torque capacity of the engagement mechanism may be set to less than the predetermined transmission torque capacity, provided that the shift range is the parking range. In addition, this invention may further include a planetary gear mechanism having a rotating element to which the output shaft of the damper mechanism is connected, a rotating element to which a motor is connected, and a rotating element to which the speed change mechanism is connected, and the engagement mechanism may be configured to be able to change the torque capacity transmitted between the planetary gear mechanism and the speed change mechanism. In the present invention, catalyst warm-up control for warming up the catalyst device may be executed after the engine speed has increased to a predetermined speed at which the engine can rotate autonomously. [Effects of the Invention]

[0007] According to the present invention, when the vehicle is stopped and the engine is operating at a predetermined operating point to warm up the catalytic converter, the torque transmission capacity of the engagement mechanism is set to a predetermined capacity or less to reduce the torque transmitted between the engine and the transmission mechanism. In other words, the inertia torque of a member that rotates integrally with the output member of the damper mechanism, which damps engine torque pulsation, can be reduced. As a result, the frequency at which the torque transmitted from the engine to the transmission mechanism is maximized can be changed. In other words, the resonant frequency of the torsional members from the engine to the transmission mechanism can be changed. Therefore, even when the engine is driven at a required operating point for warming up the catalytic converter, it is possible to suppress collision noise (clack noise) at the engagement portions and gear meshing portions of the components between the engine and the transmission mechanism due to resonance with the engine torque pulsation. In other words, the configuration of the damper mechanism can be determined according to the operating point of the engine when the vehicle is running, thereby suppressing restrictions on the design flexibility of the components that make up the powertrain. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams for explaining an example of a vehicle according to an embodiment of the present invention, in which FIG. 1A shows a skeleton diagram for explaining the configuration, FIG. 1B shows an engagement table, and FIG. 1C shows a nomographic diagram. [Figure 2] FIG. 1 is a diagram showing a torsion system model of a torque transmission path from an engine to a drive wheel. [Figure 3] 4 is a flowchart illustrating an example of control by the control device according to the present embodiment. [Figure 4] 4 is a time chart for explaining changes in the shift range, driving force, engine speed, second motor speed, hydraulic pressure command value of the first clutch mechanism, command torque of the second motor, and command torque of the first motor when the control example shown in FIG. 3 is implemented. [Figure 5] FIG. 4 is a diagram showing changes in torque transmission characteristics depending on whether or not the first clutch mechanism is engaged. [Figure 6]FIG. 4 is a diagram showing an example of a map for determining a coefficient for determining whether or not to execute control according to ignition efficiency and engine power. [Figure 7] 5 is a diagram showing an example of a map for determining a coefficient for determining whether or not to execute control in accordance with fluctuations in the engine rotation speed and fluctuations in the first motor rotation speed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Fig. 1(a) shows a skeleton diagram for explaining an example of a vehicle according to an embodiment of the present invention. The vehicle Ve shown in Fig. 1 is a hybrid vehicle using an engine (E / G) 1 and two motors 2 and 3 as driving power sources. The engine 1 and the motors 2 and 3 can be configured in the same manner as the engines and motors mounted on conventional hybrid vehicles.

[0010] A power split mechanism 6 that splits the torque of the engine 1 (hereinafter referred to as engine torque) between a first motor (MG1) 2 and an output member 5 is connected to an output shaft 4 of the engine 1. Specifically, the engine 1 and the power split mechanism 6 are connected via a spring damper 14 and a hysteresis 15, which will be described later. The power split mechanism 6 is configured with a single-pinion planetary gear mechanism, in which the output shaft 4 of the engine 1 is connected to a carrier Ca0, the first motor 2 is connected to a sun gear S0, and the output member 5 is connected to a ring gear R0. A second motor (MG2) 3 is connected to the output member 5. The engine 1 and the power split mechanism 6 are arranged side by side on the same axis, and a damper mechanism (not shown) is provided between the engine 1 and the power split mechanism 6 to reduce torque pulsation of the engine 1.

[0011] The output member 5 of the power split mechanism 6 is equipped with a stepped transmission mechanism (hereinafter simply referred to as the transmission mechanism) 7 that can change the speed ratio between the output member 5 and the drive wheels. This transmission mechanism 7 is configured to be able to set a plurality of gears, similar to transmission mechanisms provided in conventional vehicles, and in the example shown in Fig. 1, is configured to be able to set first to fourth forward gears and first reverse gear.

[0012] Specifically, the speed change mechanism 7 is made up of two single-pinion planetary gear mechanisms 8 and 9, two clutch mechanisms C1 and C2, two brake mechanisms B1 and B2, and one one-way clutch F1. car mechanism 8 The sun gear S1 in the planetary gear mechanism 9 is selectively lockable by a first brake mechanism B1, the carrier Ca1 is selectively connectable to an output member 5 by a second clutch mechanism C2, and the ring gear R1 is connected to a drive wheel so as to transmit torque. The sun gear S2 in the planetary gear mechanism 9 on the right side of FIG. 1 is selectively connectable to an output member 5 by a first clutch mechanism C1, the carrier Ca2 is connected to a drive wheel so as to transmit torque, and the ring gear R2 is selectively lockable by a second brake mechanism B2. The carrier Ca1 and the ring gear R2 are always connected to each other, and a one-way clutch F1 is provided to prohibit the carrier Ca1 and the ring gear R2 from rotating in the direction opposite to that of the engine 1. The clutch mechanisms C1, C2 and brake mechanisms B1, B2 are configured to be able to control the transmission torque capacity of a friction-type engagement mechanism or the like. The first clutch mechanism C1 corresponds to the "engagement mechanism" in the embodiment of the present invention. In addition, a sensor (e.g., resolver) 10 that detects the rotation speed of the first motor 2, a sensor (e.g., resolver) 11 that detects the rotation speed of the second motor 3, and a sensor 12 that detects the output rotation speed of the transmission mechanism 7 are provided.

[0013] FIG. 1(b) shows the clutch mechanisms C1, C2, brake mechanisms B1, B2, and one-way clutch F1 that are engaged when setting each gear in the transmission mechanism 7, and FIG. 1(c) shows a nomographic diagram that shows the operating state of each rotating element.

[0014] Figure 2 shows a torsion system model of the torque transmission path from the engine 1 to the drive wheels. As shown in Figure 2, a flywheel (F / W) 13, which functions as a mass damper, and a spring damper 14, which functions as a dynamic damper, are connected in series to the output shaft 4 of the engine 1. Note that hysteresis exists in the spring damper 14 depending on the inertia of the members that make up the spring damper 14, and Figure 2 shows a portion 15 that functions as this hysteresis.

[0015] Furthermore, in addition to the spring damper 14, examples of members that apply an elastic force to the torsional torque include a propeller shaft (P / S) 16, which is the output shaft of the speed change mechanism 7, and a drive shaft (D / S) 18 that is connected to the propeller shaft 16 via a differential gear unit (Diff) 17. In addition to the flywheel 13, examples of members that apply an inertial force to the torsional torque include the first motor 2 and the second motor 3.

[0016] The engine 1 generates power (torque) by burning a mixture of air and fuel in each cylinder. Therefore, engine torque pulsates due to various factors such as variations in the configuration of the cylinders and variations in combustion efficiency.

[0017] Therefore, the above-mentioned flywheel 13 and spring damper 14 are configured to reduce the pulsation of the engine torque when the vehicle is running, based on the elastic force of the propeller shaft 16, drive shaft 18, etc., and the inertial force of each motor 2, 3.

[0018] On the other hand, when the catalytic converter for purifying the exhaust gases of the engine 1 is warmed up while the vehicle is stopped, the operating point or ignition timing of the torque, rotation speed, etc. of the engine 1 differs from when the vehicle is running, and as a result, collision noises (clashing noises) may occur at the engagement point between the output shaft of the spring damper 14 and the input shaft of the power split mechanism 6, or at the meshing points of the gears that make up the power split mechanism 6.

[0019] Therefore, the vehicle control device in this embodiment is configured to change the torque transmission characteristics by disengaging the first clutch mechanism C1 when the engine 1 is operating at a predetermined operating point to warm up the catalyst device while the vehicle is stopped. A flowchart for explaining an example of this control is shown in Figure 3. In the example shown in Figure 3, first, it is determined whether the shift range is the parking range (P range) (step S1).

[0020] If the shift range is not in the P range and the answer to step S1 is negative, the clutch engagement control is executed (step S2), and this routine is temporarily terminated. Specifically, the clutch mechanisms C1 and C2 and the brake mechanisms B1 and B2 are engaged to set the gear position according to the vehicle speed, accelerator opening, etc.

[0021] Conversely, if the shift range is in the P range and the answer in step S1 is affirmative, it is determined whether catalyst warm-up control is being executed (step S3). This step S3 can be determined based on whether a flag for warming up the catalyst device by other control is on, or based on the temperature of the catalyst device, the command torque or target rotation speed of the engine 1, etc.

[0022] If the answer to step S3 is negative because catalyst warm-up control is not being executed, the process proceeds to step S2. Here, since the P range is selected and the vehicle is stopped, the transmission mechanism 7 is set to the first forward gear to improve responsiveness when restarting. That is, the first clutch mechanism C1 and the second brake mechanism B2 are engaged.

[0023] On the other hand, if the answer to step S3 is YES because catalyst warm-up control is being executed, clutch release control is executed (step S4), and this routine is temporarily terminated. This clutch release control is control for reducing the torque transmission capacity between the engine 1 and the transmission mechanism 7 below the transmission torque capacity when the transmission mechanism 7 is set to the first forward gear, and in this case, the transmission torque capacity of the first clutch mechanism C1 is set to a predetermined capacity or less. This predetermined capacity may be 0. Specifically, if the first clutch mechanism C1 is a hydraulic clutch that controls the transmission torque capacity by hydraulic pressure, the hydraulic pressure command value is set to a command value that allows oil to be filled into the hydraulic chamber, i.e., so-called fast fill.

[0024] Figure 4 is a time chart to explain the changes in the shift range, driving force, engine speed (ENG speed), second motor 3 speed (MG2 speed), hydraulic pressure command value of the first clutch mechanism C1 (C1 clutch hydraulic pressure), command torque of the second motor 3 (MG2 torque), and command torque of the first motor 2 (MG1 torque) when the P range is selected and warm-up control of the catalytic converter is in progress.

[0025] At time t0 in Figure 4, the engine 1 is stopped while the vehicle is parked. Therefore, the driving force, engine speed, rotation speed of the second motor 3, and command torque of each of the motors 2 and 3 are all zero. In contrast, the transmission mechanism 7 is set to the first forward gear to improve responsiveness when starting off. In other words, the hydraulic pressure command value for the first clutch mechanism C1 is set high enough to maximize the transmission torque capacity of the first clutch mechanism C1.

[0026] When a request to start engine 1 is made (at time t1) because the remaining charge of a power storage device (not shown) falls below a lower threshold, for example, the torque of first motor 2 increases in the positive direction to crank engine 1. In this case, a torque for reverse driving acts on output member 5 of power split mechanism 6, and therefore second motor 3 also outputs a positive torque to offset that torque. As a result, at time t1, the engine speed begins to increase while the driving force remains zero.

[0027] At time t2, the engine speed increases to the target speed, thereby reducing the torque of each motor 2, 3. At time t3, control to warm up the catalytic converter begins. As a result, step S4 in FIG. 3 is executed, causing the oil pressure of the first clutch mechanism C1 to begin to decrease. When the oil pressure decreases to a predetermined pressure, the first clutch mechanism C1 begins to slip. Specifically, the second motor 3 begins to rotate in the negative direction. The rotation direction of the second motor 3 is determined by the inertia torque of the first motor 2 and the second motor 3 and the gear ratio of the power split mechanism 6.

[0028] At time t5, the transmission torque capacity of the first clutch mechanism C1 has decreased to a predetermined capacity. Here, in order to prevent the engine speed from increasing, torque in the negative direction is output from the first motor 2 and the second motor 3.

[0029] Then, at time t6, the drive range (D range) is selected, and the oil pressure of the first clutch mechanism C1 begins to increase to establish first forward gear, and the torque of the second motor 3 begins to return toward 0 to reduce the slip ratio. As a result, at time t7, the slip of the first clutch mechanism C1 is eliminated, the rotation speed of the second motor 3 becomes 0, and the torque of the second motor 3 is set to 0. Thereafter, as the required driving force increases due to depression of the accelerator pedal, for example, the torque of the second motor 3 is increased, and as a result, the driving force begins to increase.

[0030] 5 is a diagram comparing the output torque (damper output torque) of the spring damper 14 and hysteresis 15 in response to engine torque when the first clutch mechanism C1 is maintained in an engaged state, in other words, the transmission characteristics (comparison example) of the torque transmitted to the output side portion (hereinafter referred to as the damper output shaft) 4a of the spring damper 14 and hysteresis 15, with the transmission characteristics (example) of the torque transmitted to the damper output shaft 4a in response to engine torque when the transmission torque capacity of the first clutch mechanism C1 is reduced to a predetermined capacity or less. In FIG. 5, the horizontal axis represents torque frequency and the vertical axis represents gain, with the example shown by a solid line and the comparative example shown by a dashed line. Furthermore, the arrow indicates the frequency of the engine torque when the engine 1 is operated at a predetermined operating point to warm up the catalytic converter.

[0031] As shown in FIG. 5, by reducing the torque transmission capacity of the first clutch mechanism C1 to a predetermined capacity or less, the frequency at which the torque transmitted to the damper output shaft 4a is maximized shifts to a higher frequency than in the comparative example. In other words, the resonant frequency of the torsional components extending from the engine 1 to the damper output shaft 4a can be changed. As a result, even when the engine 1 is driven at an operating point required for the engine 1 to warm up the catalytic converter, it is possible to prevent collision noise (clashing noise) from resonating with engine torque pulsation at the engagement portion between the damper output shaft 4a and the input shaft of the power split mechanism 6 or at the meshing portions of the gears constituting the power split mechanism 6. In other words, the configuration of the spring damper 14 can be determined according to the operating point of the engine 1 during vehicle operation, thereby preventing limitations on the design freedom of the components constituting the powertrain.

[0032] Furthermore, as shown in FIG. 4, after starting the engine 1, more specifically, after the engine speed has increased to a speed at which the engine can rotate independently, the transmission torque capacity of the first clutch mechanism C1 is reduced, thereby making it possible to suppress the generation of abnormal noise generated in the power split mechanism 6 when the engine is started.

[0033] As described above, the reduction in the transmission torque capacity of the first clutch mechanism C1 may result in a decrease in responsiveness when restarting. Therefore, the control device according to the embodiment of the present invention may be configured to execute control in accordance with the ignition efficiency and engine power of the engine 1 in order to suppress the decrease in responsiveness when restarting. Specifically, as shown in FIG. 6(a), as the ignition efficiency increases, and decreases A coefficient K1 that increases as the engine power increases and a coefficient K2 that increases as the engine power increases as shown in FIG. 6(b) may be stored in advance in the electronic control device, and the control example shown in FIG. 3 may be executed when the sum of these coefficients becomes larger than a predetermined value α.

[0034] Furthermore, in order to suppress a decrease in responsiveness when restarting, control may be executed when vibration occurs. Specifically, a coefficient K3 that increases as the fluctuation in engine speed increases as shown in Fig. 7(a) and a coefficient K4 that increases as the fluctuation in the speed of the first motor 2 increases as shown in Fig. 7(b) may be stored in advance in the electronic control device, and when the sum of these coefficients exceeds a predetermined value β, it may be determined that vibration has occurred and the control example shown in Fig. 3 may be executed. [Explanation of symbols]

[0035] 1 engine 2,3 Motor 4a Damper output shaft 5 Output member 6 Power split mechanism 7. Transmission mechanism 13 Flywheel 14 Spring damper 15 (Hysteresis) 16 Propeller shaft 18 Drive shaft B1, B2 brake mechanism C1, C2 clutch mechanism Vehicle

Claims

1. A control device for a vehicle including an engine, a catalytic converter that purifies exhaust gas from the engine, a transmission mechanism that can change a gear ratio between the engine and drive wheels, and a damper mechanism that damps torque pulsation of the engine between the engine and the transmission mechanism, the transmission mechanism includes an engagement mechanism that can change the torque capacity transmitted between the transmission mechanism and the engine, When the vehicle is stopped and the engine is operating at a predetermined operating point to warm up the catalytic converter, the torque transmission capacity of the engagement mechanism is set to be less than the predetermined torque transmission capacity when the vehicle is stopped and the catalytic converter is not warmed up. A vehicle control device characterized by:

2. A control device for a vehicle according to claim 1, On the condition that the shift range is the parking range, the transmission torque capacity of the engagement mechanism is set to be less than the predetermined transmission torque capacity. A vehicle control device characterized by:

3. A control device for a vehicle as described in claim 1, a planetary gear mechanism having a rotating element connected to an output shaft of the damper mechanism, a rotating element connected to a motor, and a rotating element connected to the speed change mechanism, The engagement mechanism is configured to be able to change the torque capacity transmitted between the planetary gear mechanism and the speed change mechanism. A vehicle control device characterized by:

4. A control device for a vehicle according to claim 3, The catalyst warm-up control for warming up the catalytic converter is executed after the engine speed increases to a predetermined speed at which the engine can rotate autonomously. A vehicle control device characterized by:

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