Vehicle control devices

Abstract

This suppresses vehicle vibrations when increasing drive shaft torque towards the required torque. [Solution] A vehicle control device used in a vehicle equipped with a drive device that outputs power to a drive shaft connected to an axle, which controls the drive device so that when increasing the drive shaft torque output to the drive shaft toward a required torque, the rate of increase of the drive shaft torque with respect to time is a first rate of increase until a first time has elapsed, and a second rate of increase from the time of the first time until a second time has elapsed, wherein the second time is the reciprocal of the resonant frequency of a torsional vibration system including at least the axle and the drive shaft, and the time required until the drive shaft torque becomes the required torque is an integer multiple of the reciprocal.

Description

Technical Field

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

Background Art

[0002] Conventionally, as this type of vehicle control device, there has been proposed one used for a vehicle equipped with a drive device that outputs power to a drive shaft connected to an axle (see, for example, Patent Document 1). In this device, when increasing the drive shaft torque output to the drive shaft toward the required torque, the increase rate of the drive shaft torque with respect to time becomes the first increase rate until the first time elapses, and the second increase rate until the second time elapses after the first time elapses. The drive device is controlled so as to be. And the second time is set as the reciprocal of the resonance frequency of the torsional vibration system including at least the axle and the drive shaft. Thereby, the vibration of the torsional vibration system is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described vehicle control device, the vibration when increasing the drive shaft torque at the first increase rate cannot be suppressed. Therefore, when increasing the drive shaft torque toward the required torque, there is a period during which the vibration of the vehicle cannot be suppressed.

[0005] The main object of the vehicle control device of the present disclosure is to suppress the vibration of the vehicle when increasing the drive shaft torque toward the required torque.

Means for Solving the Problems

[0006] The vehicle control device of the present disclosure has taken the following means to achieve the above main object.

[0007] The vehicle control device disclosed herein is A vehicle control device used in a vehicle equipped with a drive device that outputs power to a drive shaft connected to an axle, wherein when increasing the drive shaft torque output to the drive shaft toward a required torque, the control device controls the drive device such that the rate of increase of the drive shaft torque with respect to time is a first rate of increase until a first time has elapsed, and a second rate of increase from the time the first time has elapsed until a second time has elapsed, The second time is the reciprocal of the resonant frequency of the torsional vibration system, which includes at least the axle and the drive shaft. The time required for the drive shaft torque to reach the required torque is an integer multiple of the reciprocal. This is the gist of it.

[0008] In the vehicle control device of this disclosure, the second time is set to the reciprocal of the resonant frequency of the torsional vibration system, which includes at least the axle and the drive shaft, and the time required for the drive shaft torque to reach the required torque is set to an integer multiple of the reciprocal. As a result, the vehicle control device of this disclosure can suppress vibrations of the torsional vibration system when increasing the drive shaft torque toward the required torque. Consequently, the vehicle control device of this disclosure can suppress vehicle vibrations when increasing the drive shaft torque toward the required torque. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of a hybrid vehicle equipped with the vehicle control device of this embodiment. [Figure 2] This flowchart shows an example of an acceleration control routine executed by the ECU. [Figure 3] This is an explanatory diagram showing an example of the time variation of drive shaft torque Td and vehicle acceleration α. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of a hybrid vehicle equipped with the vehicle control device of this embodiment. As shown in the figure, the hybrid vehicle 20 of this embodiment includes an engine 22, a motor 30, an inverter 32, a transmission 40, a battery 50, and an electronic control unit (hereinafter referred to as "ECU") 70.

[0011] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel from a fuel tank. The crankshaft (output shaft) 23 of this engine 22 is connected to the input shaft of the transmission 40.

[0012] The motor 30 is configured as a synchronous generator-motor and has a rotor with permanent magnets embedded in a rotor core and a stator with three-phase coils wound around a stator core. The rotating shaft 31 to which the rotor of the motor 30 is fixed is connected to the drive shaft 42 via a gear mechanism 33. The drive shaft 42 is connected to the axle via a differential gear 48. The inverter 32 is used to drive the motor 30 and is connected to the battery 50 via a power line 54. The motor 30 is rotationally driven by the switching of multiple switching elements of the inverter 32.

[0013] The transmission 40 is configured as an automatic transmission with 4, 6, 8, or 10 speeds, and includes an input shaft connected to the crankshaft 23 of the engine 22, a torque converter, an output shaft connected to the drive shaft 42, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches and brakes). Each of the multiple friction engagement elements has a hydraulic servo consisting of a piston, multiple friction engagement plates (friction plates and separator plates), and an oil chamber to which hydraulic fluid is supplied. The transmission 40 connects the input shaft and the output shaft (transmitting power between them) or disconnects the input shaft and the output shaft by engaging or disengaging the multiple friction engagement elements.

[0014] The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the inverter 32 via the power line 54 as described above.

[0015] The ECU70, although not shown in the diagram, is a microcomputer equipped with a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the ECU70 via its input ports. Signals input to the ECU 70 include: values ​​detected from various sensors for detecting the state of the engine 22, such as a crank position sensor for detecting the rotational position of the crankshaft 23 of the engine 22; values ​​detected from various sensors a for detecting the state of the motor 30, such as a rotational position sensor for detecting the rotational position of the rotor (rotating shaft 31) of the motor 30; rotational speed Ni from a rotational speed sensor for detecting the rotational speed of the input shaft of the transmission 40; rotational speed No from a rotational speed sensor for detecting the rotational speed of the output shaft of the transmission 40; values ​​detected from various sensors for detecting the state of the battery 50, such as voltage Vb from a voltage sensor for detecting the voltage of the battery 50; a start signal from the start switch 80; a shift position SP from a shift position sensor 82 for detecting the operating position of the shift lever 81; accelerator opening Acc from an accelerator pedal position sensor 84 for detecting the amount of depression of the accelerator pedal 83; brake pedal position BP from a brake pedal position sensor 86 for detecting the amount of depression of the brake pedal 85; and vehicle speed V from a vehicle speed sensor 87. Various control signals are output from the ECU 70 via output ports. Examples of control signals output from the ECU 70 include driving control signals to the engine 22, drive signals to the inverter 32, and drive signals to multiple friction engagement elements for the hydraulic drive of the transmission 40.

[0016] The hybrid vehicle 20 equipped with the vehicle control device of this embodiment, configured in this way, operates in hybrid driving (HV driving) mode and electric driving (EV driving) mode. HV driving mode is a driving mode in which the vehicle is driven with the engine 22 in operation. EV driving mode is a driving mode in which the clutch of the transmission 40 is released and the vehicle is driven using power from the motor 30 without power output from the engine 22 to the drive shaft 42. In HV driving mode and EV driving mode, the ECU 70 sets a target gear position St* for the transmission 40 based on the accelerator opening Acc and the vehicle speed V, and controls the transmission 40 so that the gear position St of the transmission 40 becomes the target gear position St*. It also sets a required torque Td* based on the accelerator opening Acc and the vehicle speed V, and controls the engine 22 and the motor 30 so that the drive shaft torque Td output to the drive shaft 42 becomes the required torque Td*.

[0017] Next, the operation of the hybrid vehicle 20 of this embodiment, as configured in this way, will be described in particular, the operation during acceleration. Figure 2 is a flowchart of an example of an acceleration control routine executed by the ECU. This routine is executed by the CPU of the ECU 70 when the CPU determines that acceleration has started. The ECU 70 determines that acceleration has started when the accelerator pedal opening Acc is pressed down significantly (for example, when the accelerator pedal 83 is pressed down 80% or more, with the total amount of depression being 100%).

[0018] When this routine is executed, the ECU 70 receives the accelerator pedal position sensor 84's accelerator opening degree Acc, the vehicle speed sensor 87's vehicle speed V, and the currently set requested torque Td* as input (S100). Then, the ECU 70 sets the requested torque Td* input in S100 to the starting torque Ti (S110). Furthermore, the ECU 70 sets the requested torque Td* based on the accelerator pedal position sensor Acc and vehicle speed V input in S100 (S120).

[0019] Subsequently, the ECU 70 sets the drive shaft torque Td output to the drive shaft 42 so that the drive shaft torque Td changes from the starting torque Ti toward the required torque Td* at three timings of the first, second, and third times t1, t2, and t3, and controls the engine 22 and the motor 30 (inverter 32) so that the drive shaft torque Td is output to the drive shaft 42 (S130 to S160), and ends this routine.

[0020] In S130, the ECU 70 sets the three timings of the first, second, and third times t1, t2, and t3, the value n described later, and the second and third increase rates k2 and k3. The ECU 70 sets the first time t1 as the time until the drive shaft torque Td reaches the predetermined torque Tref when the drive shaft torque Td is increased at the first increase rate k1 with respect to time after determining that it is during acceleration. The first increase rate k1 is the increase rate of the torque of the drive shaft 42 predetermined as an increase rate at which the occurrence of vibration due to backlash filling of the gears is suppressed in the torsional vibration system including the drive shaft 42, the gear mechanism 33, the differential gear 48, and the axle. The ECU 70 sets the second time t2 to the reciprocal of the resonance frequency f of the torsional vibration system. Also, until the elapsed time t after determining that it is during acceleration has passed the second time t2 after passing the first time t1, the increase rate k of the drive shaft torque Td becomes the second increase rate k2, and thereafter, until the elapsed time t has passed the third time t3, the increase rate k of the drive shaft torque Td becomes the third increase rate k3, the drive shaft torque Td becomes the required torque Td* at the third time t3, and the third time t3 is set to n times the reciprocal of the resonance frequency f of the torsional vibration system (n is an integer of 1 or more) so that the third time t3, the second and third increase rates k2 and k3 are set. The value n may be the smallest value among the integers that make the third time t3 longer than the second time t2, or may be a value determined in advance by experiments, analysis, machine learning, etc. The second increase rate k2 is set to a value larger than the first and third increase rates k1 and k3.

[0021] In S140, the ECU 70 creates a map showing the relationship between the drive shaft torque Td and time t using the set first, second, and third times t1, t2, t3, the second and third increase rates k2, k3, the predetermined first increase rate k1, the starting torque Ti, and the required torque Td*. In the map, the ECU 70 sets the drive shaft torque Td to increase at the first increase rate k1 until the elapsed time t after the start of acceleration has passed the first time t1, to increase at the second increase rate k2 until the elapsed time t has passed the second time t2 after passing the first time t1, and to increase at the third increase rate k3 until the elapsed time t has passed the third time t3 after passing the second time t2, so as to reach the required torque Td*. The relationship between the drive shaft torque Td and time t is determined.

[0022] When the ECU 70 creates the map, in S150, it sets the drive shaft torque Td using the elapsed time t and controls the engine 22 and the motor 30 so that the drive shaft torque Td is output to the drive shaft 42. Then, it determines whether the elapsed time t has passed the third time t3 (S160), and repeats the processes of S150 and S160 until the time t has passed the third time t3. When the time t has passed the third time t3 in S160, this routine ends.

[0023] Figure 3 is an explanatory diagram showing an example of the time variation of drive shaft torque Td and vehicle acceleration α. ​​In the figure, the solid line shows an example of the time variation of drive shaft torque Td and vehicle acceleration α in the hybrid vehicle 20 of the embodiment. The dashed line shows an example of the time variation of drive shaft torque Td and vehicle acceleration α in the hybrid vehicle of the comparison embodiment. In the hybrid vehicle of the comparison embodiment, after the second time t2 has elapsed, the rate of increase k of drive shaft torque Td is set to the fourth rate of increase k4. The fourth rate of increase k4 is a rate of increase that has been predetermined by experiment, analysis, and machine learning as the rate of increase when rapidly increasing the drive shaft torque Td to the required torque Td*. As shown in the figure, in the comparison embodiment, although the drive shaft torque Td rapidly reaches the required torque Td*, the vehicle acceleration α oscillates, indicating that vibration occurs in the vehicle. In this embodiment, the drive shaft torque Td is increased at a first rate of increase k1 until the elapsed time t reaches the first time t1, and then increased at a second rate of increase k2 from the time the first time t1 has elapsed until the second time t2 has elapsed. The third time t3, i.e., the time required until the drive shaft torque Td becomes the required torque Td*, is set to n times (integer multiple) the reciprocal of the resonant frequency f. As a result, the vibration of the vehicle acceleration α is reduced compared to the comparative embodiment, and the vibration of the torsional vibration system is suppressed. This is based on setting the second time t2 to the reciprocal of the resonant frequency f of the torsional vibration system, and the third time t3 to n times the reciprocal of the reciprocal of the resonant frequency f. In this way, the hybrid vehicle 20 equipped with the vehicle control device of this embodiment can suppress the vibration of the torsional vibration system. As a result, when the hybrid vehicle 20 increases the drive shaft torque Td toward the required torque Td*, the vibration of the hybrid vehicle 20, i.e., the vehicle, can be suppressed.

[0024] According to the hybrid vehicle 20 equipped with the vehicle control device of the embodiment described above, by setting the second time t2 to the reciprocal of the resonance frequency f of the torsional vibration system including at least the axle, drive shaft 42, and gear mechanism 33, and setting the time required until the drive shaft torque Td becomes the required torque Td* (third time t3) to n times (integer multiple) the reciprocal of the resonance frequency f, vehicle vibration can be suppressed when increasing the drive shaft torque Td toward the required torque Td*.

[0025] In the embodiment described above, the hybrid vehicle 20 includes an engine 22, a motor 30, and a transmission 40. However, the hybrid vehicle 20 only needs to include an engine and a motor, and may also be configured to include, for example, an engine, first and second motors, and planetary gears.

[0026] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the engine 22, transmission 40, and motor 30 correspond to the "drive unit," and the ECU 70 corresponds to the "vehicle control unit."

[0027] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0028] The above describes the forms for implementing this disclosure using embodiments, but this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0029] This disclosure can be used in industries such as the manufacturing of vehicle control devices. [Explanation of symbols]

[0030] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 30 Motor, 31 Rotating shaft, 32 Inverter, 33 Gear mechanism, 40 Transmission, 42 Drive shaft, 48 Differential gear, 49 Drive wheel, 50 Battery, 54 Power line, 70 Electronic control unit (ECU), 80 Start switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 87 Vehicle speed sensor.

Claims

[Claim 1] A vehicle control device used in a vehicle equipped with a drive device that outputs power to a drive shaft connected to an axle, wherein when increasing the drive shaft torque output to the drive shaft toward a required torque, the control device controls the drive device such that the rate of increase of the drive shaft torque with respect to time is a first rate of increase until a first time has elapsed, and a second rate of increase from the time the first time has elapsed until a second time has elapsed, The second time is the reciprocal of the resonant frequency of the torsional vibration system, which includes at least the axle and the drive shaft. The time required for the drive shaft torque to reach the required torque is an integer multiple of the reciprocal. Vehicle control device.

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