JP2024070447A - Vehicle control device - Google Patents

Abstract

To inhibit execution of an unnecessary fail-safe.SOLUTION: An output shaft of an internal combustion engine 10 is connected to a transmission part 44 through a first damper 20 and a second damper 50. A control device 100 executes a fail-safe in which torque applied from the internal combustion engine 10 to a vehicle drive system is reduced when first torque, which is torsion torque occurring in the first damper 20, is larger than a first determination value or when second torque, which is torsion torque occurring in a second damper 50, is larger than a second determination value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle control device.

For example, in the vehicle described in Patent Document 1, the output shaft of the internal combustion engine is connected to the rear shaft, the transmission, via one torsion element. The control device of this vehicle then suppresses the occurrence of vibrations by implementing a fail-safe that controls the torque of the internal combustion engine so that it is outside the vibration generation region when the required torque of the internal combustion engine is within the vibration generation region.

JP 2013-181485 A

However, when a vehicle's driveline is equipped with multiple torsional elements, if the torque region is set so that no vibration occurs in any of the torsional elements, the damper tolerances of the torsional elements will accumulate. As a result, there is a risk that the fail-safe will be activated even in a region where no vibration occurs in any of the torsional elements.

A vehicle control device that solves the above problem is a vehicle control device in which an output shaft of an internal combustion engine is connected to a rear shaft via a first torsion element and a second torsion element, a first sensor is disposed between the output shaft and the first torsion element, a second sensor is disposed between the first torsion element and the second torsion element, and a third sensor is disposed between the second torsion element and the rear shaft. This control device executes a determination process that determines whether the calculated torque is greater than a predetermined determination value, and a fail-safe process that, if it is determined that the calculated torque is greater than the determination value, executes a fail-safe that reduces the torque applied from the internal combustion engine to the vehicle driveline compared to before it was determined that the calculated torque is greater. The determination process includes a process of determining whether a first torque, which is a torsional torque generated in the first torsion element and is calculated based on the detection value of the first sensor and the detection value of the second sensor, is greater than a predetermined first determination value, and a process of determining whether a second torque, which is a torsional torque generated in the second torsion element and is calculated based on the detection value of the second sensor and the detection value of the third sensor, is greater than a predetermined second determination value. The fail-safe process executes the fail-safe when the first torque is greater than the first determination value or when the second torque is greater than the second determination value.

With this configuration, a judgment value for whether or not to perform a fail-safe is set for each torsion element, which prevents the accumulation of damper tolerances for the torsion elements. Therefore, unnecessary execution of the fail-safe can be prevented.

1 is a schematic diagram of a vehicle according to an embodiment. 4 is a flowchart showing a procedure of a process executed by the control device of the embodiment. FIG. 11 is a schematic diagram of a transmission section in a modified example of the same embodiment.

Hereinafter, an embodiment of a vehicle control device will be described with reference to FIG. 1 and FIG.
As shown in FIG. 1 , a vehicle 500 is a hybrid vehicle equipped with two prime movers, that is, an internal combustion engine 10 and a motor generator 30 .

The output shaft of the internal combustion engine 10 is connected to the vehicle drive system of the vehicle 500. That is, the output shaft of the internal combustion engine 10 is connected to a first damper 20 that constitutes part of the vehicle drive system. This first damper 20 is a first torsion element. The first damper 20 is equipped with a spring that damps torsional vibrations. The first damper 20 is connected to the rotating shaft of the motor generator 30. Note that a clutch mechanism (not shown) is provided between the output shaft of the internal combustion engine 10 and the rotating shaft of the motor generator 30.

The rotating shaft of the motor generator 30 is connected to the input shaft of the automatic transmission 40, which constitutes part of the vehicle drive system. The automatic transmission 40 has a torque converter (not shown) and a transmission unit 44 that changes the gear ratio. The torque converter has a lock-up clutch mechanism 42 and a second damper 50. The second damper 50 is a second torsion element. The second damper 50 is provided between the lock-up clutch mechanism 42 and the input shaft of the transmission unit 44.

The output shaft of the transmission unit 44 is connected to a drive shaft 60 that constitutes part of the vehicle drive system. This drive shaft 60 is the third torsion element. The drive shaft 60 is connected to the drive wheels 70 of the vehicle 500 via a differential gear (not shown).

A crank angle sensor 81 is provided on the output shaft of the internal combustion engine 10. The engine speed NE, which is the rotation speed of the output shaft of the internal combustion engine 10, is calculated based on the detection signal of the crank angle sensor 81. The crank angle sensor 81 is a first sensor disposed between the output shaft of the internal combustion engine and the first torsion element.

A second speed sensor 82 is provided on the rotating shaft of the motor generator 30. The motor rotation speed NM of the motor generator 30 is calculated based on the detection signal of the second speed sensor 82. The second speed sensor 82 is a second sensor disposed between the first torsion element and the second torsion element.

A third speed sensor 83 is provided on the input shaft of the transmission unit 44. The input shaft rotation speed Nin of the transmission unit 44 is calculated based on the detection signal of the third speed sensor 83. The input shaft of the transmission unit 44 is a rear shaft to which the output shaft of the internal combustion engine is connected via a first torsion element and a second torsion element. The third speed sensor 83 is a third sensor disposed between the second torsion element and the rear shaft.

A fourth speed sensor 84 is provided on the output shaft of the transmission unit 44. The output shaft rotation speed Nout of the transmission unit 44 is calculated based on the detection signal of the fourth speed sensor 84. The fourth speed sensor 84 is a fourth sensor disposed between the output shaft of the transmission unit 44 and the third torsion element. It is also possible to calculate the output shaft rotation speed Nout based on the input shaft rotation speed Nin and the gear ratio of the transmission unit 44.

The drive wheel 70 is provided with a fifth speed sensor 85. The drive wheel rotation speed Nti, which is the rotation speed of the drive wheel 70, is calculated based on the detection signal of the fifth speed sensor 85. The fifth speed sensor 85 is a fifth sensor disposed between the third torsion element and the drive wheel.

A control device 100 executes various types of control, such as output control of the internal combustion engine 10, output control of the motor generator 30, and control of the automatic transmission.
The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110 and a memory 120 in which control programs and data are stored. The CPU 110 executes the programs stored in the memory 120 to perform various controls. Although not shown, the control device 100 is composed of a plurality of control units, such as a control unit for the internal combustion engine and a control unit for the PCU. In addition to the various sensors described above, the control device 100 also receives signals from various sensors that detect the state of the internal combustion engine 10 and the state of the vehicle.

However, if the engine speed when a misfire occurs in the internal combustion engine 10 is within a predetermined speed range, resonance may occur in the vehicle drive system to which the internal combustion engine 10 is connected. If such resonance occurs, the torsional torque generated by the torsional elements described above increases, and there is a risk that excessive torque will be applied to the components of the vehicle drive system. Therefore, the control device 100 calculates the torsional torque for each torsional element. If the calculated torque is greater than a predetermined judgment value, a fail-safe is implemented to reduce the torque applied from the internal combustion engine 10 to the vehicle drive system.

Various processes related to the execution of such fail-safe measures will be described below.
The control device 100 calculates, for each predetermined period, a first torque T1, which is a torsional torque generated in the first damper 20. The first torque T1 is calculated, for example, based on the following formula (1).

T1 = K1 × θdamp1 (1)
The first spring constant K1 is a value that is obtained in advance through testing, etc. The first torsion angle θdamp1 is a torsion angle of the first damper 20, and is a value obtained by integrating a value obtained by subtracting the motor rotation speed NM from the engine rotation speed NE (θdamp1=Σ(NE-NM)). This first torque T1 is a torque applied to a member to which the first damper 20 is connected, that is, the output shaft of the internal combustion engine 10 and the rotating shaft of the motor generator 30.

Furthermore, the control device 100 calculates, for each predetermined period, a second torque T2, which is a torsional torque generated in the second damper 50. The second torque T2 is calculated, for example, based on the following equation (2).
T2=K2×θdamp2 (2)
The second spring constant K2 is a value that is obtained in advance through testing or the like. The second torsion angle θdamp2 is the torsion angle of the second damper 50, and is a value obtained by integrating the value obtained by subtracting the input shaft rotation speed Nin from the motor rotation speed NM (θdamp2=Σ(NM-Nin)). This second torque T2 is a torque that is applied to the member to which the second damper 50 is connected, that is, the input shaft of the transmission 44 and the lock-up clutch mechanism 42. Note that the torque that is applied to the lock-up clutch mechanism 42 when the lock-up clutch mechanism 42 is engaged is also a torque that is applied to the rotating shaft of the motor generator 30.

The control device 100 also calculates a third torque T3, which is a torsional torque generated in the drive shaft 60, at each predetermined period. The third torque T3 is calculated, for example, based on the following formula (3).

T3=K3×θdamp3 (3)
The third spring constant K3 is a value that is obtained in advance through testing, etc. The third torsion angle θdamp3 is a torsion angle of the drive shaft 60, and is a value obtained by integrating the value obtained by subtracting the drive wheel rotation speed Nti from the output shaft rotation speed Nout (θdamp3=Σ(Nout-Nti)). This third torque T3 is a torque applied to the member to which the drive shaft 60 is connected, that is, the output shaft of the transmission 44 and the drive wheels 70.

The control device 100 executes the process shown in Fig. 2 at predetermined intervals. In the following description, step numbers are represented by numbers preceded by the letter "S."
2 starts, the control device 100 executes a process of acquiring the first torque T1, the second torque T2, and the third torque T3 calculated through the above-mentioned process (S100). Next, the control device 100 executes a determination process of determining whether or not any of the first torque T1, the second torque T2, and the third torque T3 is greater than a predetermined determination value (S110). In the process of S110, the control device 100 executes the following determination process.

First, a first judgment value T1ref is preset as a default judgment value to be compared with the first torque T1. The first judgment value T1ref is set to, for example, the smaller of the maximum allowable torque that can be applied to the output shaft of the internal combustion engine 10 and the maximum allowable torque that can be applied to the rotating shaft of the motor generator 30.

A second judgment value T2ref is preset as a default judgment value to be compared with the second torque T2. The second judgment value T2ref is set to, for example, the smaller of the maximum allowable torque that can be applied to the rotating shaft of the motor generator 30 and the maximum allowable torque that can be applied to the input shaft of the transmission 44.

A third judgment value T3ref is preset as a default judgment value to be compared with the third torque T3. The third judgment value T3ref is set to, for example, the smaller of the maximum allowable torque that can be applied to the output shaft of the transmission unit 44 and the maximum allowable torque that can be applied to the drive wheels 70.

Then, the control device 100 makes a positive determination in the processing of S110 when the first torque T1 is greater than the first judgment value T1ref, when the second torque T2 is greater than the second judgment value T2ref, or when the third torque T3 is greater than the third judgment value T3ref.

If the control device 100 makes a positive determination in the process of S110, the control device 100 performs a fail-safe process to implement the fail-safe described above (S120). Specific examples of the fail-safe that the control device 100 implements include, for example, the following:

- If the second torque T2 is greater than the second judgment value T2ref, or if the third torque T3 is greater than the third judgment value T3ref, the lock-up clutch mechanism 42 is released.

- The output torque of the internal combustion engine 10 is reduced compared to before the positive determination was made in the processing of S110. Note that when the output torque of the internal combustion engine 10 is reduced, it is preferable to compensate for the reduced torque with the output torque of the motor generator 30.

If a negative determination is made in the process of S110, or after the process of S120 is executed, the control device 100 ends this process.
The operation and effects of this embodiment will be described.

(1) A judgment value for whether or not to execute a fail-safe is set for each of the torsion elements, the first damper 20, the second damper 50, and the drive shaft 60. This prevents the damper tolerances of the torsion elements from accumulating. This prevents the fail-safe from being executed in a torque region where no vibration occurs in any of the torsion elements, thereby preventing unnecessary execution of the fail-safe.

(2) The feasibility of implementing a fail-safe is determined for each torsion element. Therefore, the accuracy of determining whether or not a fail-safe can be implemented is improved compared to, for example, determining whether or not a fail-safe can be implemented based on the engine speed or the rotational fluctuation of the transmission 44.

The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.
As a fail-safe, the following process may be performed. That is, the slip ratio of the lock-up clutch mechanism 42 may be adjusted so that the second torque T2 is equal to or less than the second reference value T2ref. Similarly, the slip ratio of the lock-up clutch mechanism 42 may be adjusted so that the third torque T3 is equal to or less than the third reference value T3ref.

The first torque T1, the second torque T2, and the third torque T3 may be calculated using other calculation formulas.
The calculation process of each torque, such as the first torque T1, the second torque T2, and the third torque T3, and the series of processes shown in FIG. 2 may be performed on the condition that a misfire is detected in the internal combustion engine 10.

The calculation of the third torque T3 and the comparison with the third reference value T3ref may be omitted.
The torque applied to each of the multiple shafts included in the transmission 44 is calculated. Then, if the calculated torque is greater than a predetermined determination value, the fuel safe may be performed.

Figure 3 shows the configuration of the transmission unit 44 in this modified example. As shown in Figure 3, the transmission unit 44 has three shafts, for example. The first shaft 44a is the input shaft of the transmission unit 44. The third shaft 44c is the output shaft of the transmission unit 44. The second shaft 44b is an intermediate shaft that has a gear that meshes with the gear provided on the first shaft 44a and a gear that meshes with the gear provided on the third shaft 44c.

The fourth torque T4 applied to the first shaft 44a is the same as the second torque T2. The fifth torque T5 applied to the second shaft 44b is calculated by "T5 = (fourth torque T4 - inertia of the second shaft 44b x angular acceleration of the second shaft 44b) x gear ratio between the first shaft 44a and the second shaft 44b." The sixth torque T6 applied to the third shaft 44c is calculated by "T6 = (fifth torque T5 - inertia of the third shaft 44c x angular acceleration of the third shaft 44c) x gear ratio between the second shaft 44b and the third shaft 44c."

The maximum allowable torque that can be applied to the first shaft 44a is the fourth judgment value T4ref, the maximum allowable torque that can be applied to the second shaft 44b is the fifth judgment value T5ref, and the maximum allowable torque that can be applied to the third shaft 44c is the sixth judgment value T6ref. The control device 100 may then execute the above-mentioned fail-safe when the fourth torque T4 is greater than the fourth judgment value T4ref, or when the fifth torque T5 is greater than the fifth judgment value T5ref, or when the sixth torque T6 is greater than the sixth judgment value T6ref. In this case, the fail-safe can be appropriately executed for each shaft included in the transmission 44.

- The hybrid system of the vehicle 500 is not limited to the one shown in FIG. 1, but may be another hybrid system. For example, it may be a so-called series-parallel hybrid system in which the output shaft of the internal combustion engine 10 and the motor generator 30 are connected via a power split mechanism. In this case, as a fail-safe, a process for reducing the output torque of the internal combustion engine 10 may be performed. The number of motor generators provided in the vehicle 500 may be changed as appropriate. Furthermore, the vehicle 500 is not limited to a hybrid vehicle, but may be a vehicle provided with only the internal combustion engine 10 as a prime mover.

10...internal combustion engine, 100...control device, 500...vehicle.

Claims (1)

A control device for a vehicle, wherein an output shaft of an internal combustion engine is connected to a rear shaft via a first torsion element and a second torsion element, a first sensor is disposed between the output shaft and the first torsion element, a second sensor is disposed between the first torsion element and the second torsion element, and a third sensor is disposed between the second torsion element and the rear shaft,
a determination process for determining whether the calculated torque is greater than a predetermined determination value;
a fail-safe process for performing a fail-safe operation to reduce a torque applied from the internal combustion engine to a vehicle driveline when it is determined that the calculated torque is greater than the determination value;
The determination process includes a process of determining whether a first torque, which is a value calculated based on the detection value of the first sensor and the detection value of the second sensor and is a torsion torque generated in the first torsion element, is greater than a predetermined first determination value, and a process of determining whether a second torque, which is a value calculated based on the detection value of the second sensor and the detection value of the third sensor and is a torsion torque generated in the second torsion element, is greater than a predetermined second determination value,
The fail-safe process executes the fail-safe when the first torque is greater than the first determination value or when the second torque is greater than the second determination value.

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