Vehicle control system

Abstract

To provide a vehicle control device capable of suppressing shock.SOLUTION: Provided is a control device of a vehicle that comprises an internal combustion engine, a first electric motor, and a second electric motor. The control device switches between first vibration suppression control that is control of vibration using the first electric motor and the second electric motor, and second vibration suppression control that is control of vibration using one out of the first electric motor and the second electric motor, in accordance with an engine speed of the internal combustion engine.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle control device.

Background Art

[0002] A vehicle equipped with an internal combustion engine and two electric motors is known (for example, Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The electric motor generates torque to suppress the vibration of the vehicle. However, there is a risk of shock occurring in the vibration control. Therefore, an object is to provide a vehicle control device capable of suppressing shock.

Means for Solving the Problems

[0005] The above object can be achieved by a vehicle control device including an internal combustion engine, a first electric motor, and a second electric motor, which switches between a first vibration control that is vibration control using the first electric motor and the second electric motor based on the rotational speed of the internal combustion engine, and a second vibration control that is vibration control using one of the first electric motor and the second electric motor.

[0006] When the rotational speed of the internal combustion engine is less than a first value, the ratio of the torque of the first vibration control is made higher than the ratio of the torque of the second vibration control among the torques for vibration control, and when the rotational speed of the internal combustion engine is greater than or equal to a second value that is greater than the first value, the ratio of the torque of the second vibration control may be made higher than the ratio of the torque of the first vibration control.

[0007] If the rotational speed of the internal combustion engine is less than the first value, the proportion of the torque for vibration control that is used for the first vibration damping control may be set to 100%, and if the rotational speed of the internal combustion engine is equal to or greater than the second value, the proportion of the torque for the second vibration damping control may be set to 100%.

[0008] If the rotational speed of the internal combustion engine is greater than or equal to the first value and less than the second value, the torque ratio of the first vibration damping control and the torque ratio of the second vibration damping control may not be changed.

[0009] The ratio of torque for the first vibration damping control and the ratio of torque for the second vibration damping control may be changed at a predetermined rate of change. [Effects of the Invention]

[0010] We can provide a vehicle control system that can suppress shocks. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram of the vehicle according to this embodiment. [Figure 2] Figure 2 is a flowchart illustrating the processes performed by the ECU. [Figure 3] Figure 3 is an example of a time chart. [Modes for carrying out the invention]

[0012] Figure 1 is a schematic diagram of the vehicle 1 according to this embodiment. The vehicle 1 is a hybrid vehicle and includes an ECU (Electronic Control Unit) 50, an engine 10 (internal combustion engine), a first motor generator (hereinafter referred to as "first MG (Motor Generator)") 14, a second motor generator (hereinafter referred to as "second MG") 15, a PCU (Power Control Unit) 17, a battery 18, a torsional damper 19, a power split mechanism 20, a reduction mechanism 22, a differential gear 24, and drive wheels 26. The engine 10 may be a gasoline engine or a diesel engine. The engine 10, the first MG 14, and the second MG 15 are the power sources for driving the vehicle 1.

[0013] The first MG14 and the second MG15 function as an electric motor and a generator. The first MG14 and the second MG15 output torque when power is supplied to them, and generate regenerative power when torque is applied to them. The first MG14 and the second MG15 are, for example, AC rotating electric machines. An AC rotating electric machine is, for example, a permanent magnet synchronous motor equipped with a rotor in which permanent magnets are embedded.

[0014] The first MG14 and the second MG15 are electrically connected to the battery 18 via the PCU17. The PCU17 charges the battery 18 using regenerative power generated by the first MG14 or the second MG15, and drives the first MG14 or the second MG15 using the power charged by the battery 18. The PCU17 includes a first inverter that exchanges power with the first MG14, a second inverter that exchanges power with the second MG15, and a converter. The converter boosts the power from the battery 18 and supplies it to the first and second inverters, and steps down the power supplied from the first and second inverters and supplies it to the battery 18. The first inverter converts the DC power from the converter into AC power and supplies it to the first MG14, and converts the AC power from the first MG14 into DC power and supplies it to the converter. The second inverter converts the DC power from the converter into AC power and supplies it to the second MG15, and converts the AC power from the second MG15 into DC power and supplies it to the converter.

[0015] Battery 18 is composed of multiple stacked batteries. The batteries are, for example, rechargeable batteries such as nickel-metal hydride batteries and lithium-ion batteries.

[0016] The power split mechanism 20 is a planetary gear mechanism, for example, comprising a sun gear, planetary carrier, pinion gear, and ring gear. The crankshaft 27 of the engine 10 is connected to the power split mechanism 20 via a torsional damper 19. The power split mechanism 20 mechanically connects the crankshaft 27 of the engine 10, the rotating shaft of the first MG 14, and the output shaft of the power split mechanism 20.

[0017] The reduction mechanism 22 is a multi-stage automatic transmission that changes the gear ratio. Under the control of the ECU 50, the reduction mechanism 22 changes the gear ratio and switches between multiple power transmission states. These multiple power transmission states include N (neutral) range, D (drive) range, R (reverse) range, and P (parking) range. Instead of the reduction mechanism 22, a continuously variable transmission (CVT) that continuously changes the gear ratio may be used.

[0018] The output shaft of the power split mechanism 20 is connected to the reduction mechanism 22. The rotating shaft of the second MG 15 is also connected to the reduction mechanism 22. The reduction mechanism 22 is connected to the differential gear 24. A drive shaft 25 is connected to the differential gear 24. A drive wheel 26 is attached to the end of the drive shaft 25.

[0019] Engine 10, the first MG14, and the second MG15 function as drive sources that generate driving force. The driving force from engine 10, the first MG14, and the second MG15 is transmitted to the drive wheels 26 via the reduction gear 22 and the differential gear 24.

[0020] The ECU 50 is a control device for the vehicle 1 and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 50 performs various controls by executing programs stored in the ROM or the storage device. The ECU 50 acquires the rotational speed of the engine 10 detected by the rotational speed sensor 29. The ECU 50 controls the engine 10, the first MG 14, the second MG 15, the PCU 17, and the battery 18.

[0021] When the engine 10 rotates, the torque generated by the engine 10 is transmitted to the torsional damper 19, the power split mechanism 20, the reduction gear mechanism 22, the drive shaft 25, and the like. Vibration may occur in the vehicle 1 due to the transmission of torque. The ECU 50 performs vibration control using the first MG 14 and the second MG 15. The vibration control using both the torque of the first MG 14 and the torque of the second MG 15 is defined as cooperative vibration control (first vibration control). The vibration control using only the torque of the second MG 15 is defined as MG2 vibration control (second vibration control).

[0022] In the cooperative vibration control, the ECU 50 acquires the vibration mode (twisting speed, amount of twist) at the resonance frequency of the drive suspension system (power plant, torsional damper 19, drive shaft 25, etc.), and feeds back the vibration mode to adjust the torques of the first MG 14 and the second MG 15. In the MG2 vibration control, the ECU 50 feeds back the twisting speed of the drive shaft 25 to adjust the torque of the second MG 15.

[0023] In the coordinated vibration control, the state quantity that is the target of feedback and the state quantity that is the target of feedback in the MG2 vibration control partially overlap. Therefore, it is difficult to simultaneously implement the coordinated vibration control and the MG2 vibration control. The ECU 50 switches between the coordinated vibration control and the MG2 vibration control. Specifically, the ECU 50 changes the switching gain g to change the ratio of the torque T1 of the coordinated vibration control and the ratio of the torque T2 of the MG2 vibration control with respect to the torque T used for the vibration control. The torque T for the vibration control is expressed by the following formula. T = T1×g + T2×(1 - g) When the switching gain g is 1, the ratio of the torque T1 of the coordinated vibration control with respect to the torque T is 100%. The ratio of the torque T2 of the MG2 vibration control is 0%. When the switching gain g is 0, the ratio of the torque T1 with respect to the torque T is 0%. The ratio of the torque T2 is 100%. When the switching gain g is a value between 0 and 1, the ratio of the torque T1 and the ratio of the torque T2 with respect to the torque T are greater than 0% and less than 100%.

[0024] Figure 2 is a flowchart illustrating the control executed by the ECU 50. The ECU 50 determines whether there is a request for coordinated vibration control (step S10). In the case of a negative determination (No), the ECU 50 sets the switching gain g to 0 (step S18). For example, when the rotational speed of the engine 10 is increasing, it is assumed that there is a request for coordinated vibration control, and an affirmative determination (Yes) is made in step S10.

[0025] In the case of an affirmative determination in step S10, the ECU 50 determines whether the rotational speed R of the engine 10 is less than Ra (the first value) (step S12). In the case of an affirmative determination, the ECU 50 sets the switching gain g to 1 (step S16). In the case of a negative determination, the ECU 50 determines whether the rotational speed R is greater than or equal to Rb (the second value) (step S14). Rb is greater than Ra. In the case of an affirmative determination, the ECU 50 sets the switching gain g to 0 (step S18). In the case of a negative determination, the ECU 50 sets the switching gain g to the previous value without changing it (step S20). If the previous value of the switching gain g is 1, the switching gain g is maintained at 1.

[0026] After steps S16, S18, or S20, the ECU 50 changes the switching gain g at a predetermined rate (rate of change) (step S22). The ECU 50 performs vibration damping control based on the switching gain g (step S24). This completes the process shown in Figure 2.

[0027] Figure 3 is an example of a time chart. The top row of Figure 3 represents the coordinated vibration control request flag. The second row represents the rotational speed R of engine 10. The third row represents the switching gain g.

[0028] At time t0, the coordinated vibration control request flag is turned on. Between time t0 and t1, the rotational speed R of engine 10 increases but remains below Ra. The switching gain g changes from 0 to 1. The switching gain g changes continuously, not discontinuously between 0 and 1. For example, the switching gain g changes linearly with a predetermined slope. At time t1, the switching gain g reaches 1 (steps S16 and S22 in Figure 2). Coordinated vibration control is performed.

[0029] At time t2, the rotational speed R is higher than Ra. Between time t2 and t3, the rotational speed R is greater than or equal to Ra and less than Rb. The switching gain g remains at 1 (step S20). At time t3, the rotational speed R is greater than or equal to Rb. At time t3, the switching gain g begins to decrease from 1 at a predetermined rate and becomes 0 at time t4 (steps S18 and S22). The coordinated vibration control request flag is turned off. The system switches from coordinated vibration control to MG2 vibration control.

[0030] According to this embodiment, the ECU 50 switches between coordinated vibration damping control and MG2 vibration damping control based on the rotational speed R of the engine 10. This makes it possible to suppress shocks associated with the switching.

[0031] When the rotational speed R is less than Ra, the ECU50 increases the proportion of the torque T1 for coordinated vibration control in the total torque T for vibration control compared to the proportion of the torque T2 for MG2 vibration control. When the rotational speed R is Rb or greater, the ECU50 increases the proportion of the torque T2 for MG2 vibration control compared to the proportion of the torque T1 for coordinated vibration control. The ECU50 can change the torque ratio by changing the switching gain g between 0 and 1. This can suppress shocks associated with switching.

[0032] Specifically, when the rotational speed R is less than Ra, the ECU50 sets the switching gain g to 1. This makes the proportion of the torque T1 for coordinated vibration control 100% of the torque T for vibration control. When the rotational speed R is Rb or greater, the ECU50 sets the switching gain g to 0. This makes the proportion of the torque T2 for MG2 vibration control 100%. The state variables that are subject to feedback in coordinated vibration control and the state variables that are subject to feedback in MG2 vibration control partially overlap. By using the two vibration control methods appropriately, vibrations can be effectively reduced.

[0033] In the lower part of Figure 3, the dashed line shows the comparative example. In the comparative example, the threshold for rotational speed R is only Ra. The switching gain g goes from 0 to 1, and remains 1 as long as the rotational speed R is less than Ra. When the rotational speed R becomes Ra or greater at time t2, the switching gain g decreases towards 0. However, if the rotational speed R becomes less than Ra immediately after time t2, the switching gain g increases again. As shown above, in the example of the dashed line, the switching gain g changes in a short time, and the torque also changes.

[0034] According to this embodiment, when the rotational speed R is greater than or equal to Ra and less than Rb, the ECU 50 does not change the switching gain g, but uses the value it was set to last time. As shown in Figure 3, the switching gain g is maintained at 1. The ratios of torque T1 and torque T2 do not change, for example, they are maintained at 100% and 0%. Since the coordinated vibration control is continued, changes in torque are suppressed. Shocks can be effectively suppressed.

[0035] The ECU50 changes the switching gain g at a predetermined rate of change. That is, as shown in the lower part of Figure 3, the switching gain g changes linearly between 0 and 1. By preventing the switching gain g from changing abruptly between 0 and 1, sudden changes in torque are also suppressed. Shocks can be effectively suppressed.

[0036] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. [Explanation of Symbols]

[0037] 1 vehicle 10 Engines 14. First Motor Generator 15. Second Motor Generator 17 PCU 18 batteries 19 Torsional Damper 20 Power split mechanism 22 Reduction mechanism 24 Differential gear 25 Drive shaft 26 drive wheels 27 Crankshaft 29. Rotation speed sensor 50 ECU

Claims

[Claim 1] It comprises an internal combustion engine, a first electric motor, and a second electric motor. A vehicle control device that controls vibration by switching between a first vibration control using the first and second electric motors and a second vibration control using one of the first and second electric motors, based on the rotational speed of the internal combustion engine, When the first vibration damping control is requested, it is possible to change or keep unchanged the ratio of the torque for the first vibration damping control and the ratio of the torque for the second vibration damping control within the total torque for vibration control. By linearly changing the gain between 0 and 1 at a predetermined rate of change, the ratio of the torque for the first vibration damping control and the ratio of the torque for the second vibration damping control are changed in the torque for controlling the vibration. When the rotational speed of the internal combustion engine is less than the first value, the change is made by changing the gain to 1, so that the proportion of the torque for the first vibration damping control among the torque for vibration control becomes 100%. When the rotational speed of the internal combustion engine is greater than or equal to a second value which is greater than the first value, the change is made by changing the gain to 0, so that the ratio of the torque for the second vibration damping control to the torque for vibration control becomes 100%. The aforementioned non-change means that when the rotational speed of the internal combustion engine is greater than the first value and less than the second value, the gain is not changed from the value in the previous vibration control, thereby not changing the torque ratio of the first vibration damping control and the torque ratio of the second vibration damping control from the torque ratio in the previous vibration control, in a vehicle control device.

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