JP7768071B2 - Vehicle control device - Google Patents

Description

The present invention relates to a control device for a vehicle having a continuously variable transmission.

Patent Document 1 describes a method for suppressing longitudinal vibrations in a vehicle equipped with a continuously variable transmission by performing phase lead compensation on the longitudinal vibrations that occur when torque fluctuations occurring in a predetermined frequency band are coupled with the gear shifts of the continuously variable transmission.

JP 2019-52731 A

However, in Patent Document 1, the amount of compensation (gain) and the amount of phase lead during compensation depend on the designed compensator. As a result, if the characteristics shift, the amount of compensation is insufficient, or the amount of phase lead is too much or too little, it becomes necessary to redesign the compensator. This becomes particularly difficult in powertrains where the resonant frequency varies depending on the gear ratio, such as continuously variable transmissions.

The present invention was made against the backdrop of the above circumstances, and its purpose is to provide a control device for a vehicle with a continuously variable transmission that can easily suppress front-to-rear vibrations of the vehicle while it is running.

The gist of the present invention is (a) a control device for a vehicle having a continuously variable transmission capable of continuously changing a gear ratio, comprising: (b) a filter processing unit that filters a hydraulic control command value of the continuously variable transmission; (c) a vibration component extraction unit that extracts a vibration component by subtracting a calculated value after the filter processing from the hydraulic control command value; (d) a correction amount calculation unit that calculates a correction amount for the hydraulic control command value based on the vibration component so that the correction amount becomes larger the more insufficient the vibration damping effect of the vibration component is ; and (e) a command value correction unit that calculates a corrected hydraulic control command value by subtracting the correction amount from the hydraulic control command value.

According to the present invention, a hydraulic control command value is filtered, and a correction amount for the hydraulic control command value is calculated based on the vibration component extracted by subtracting the filtered calculated value from the hydraulic control command value, so that the correction amount is larger the more insufficient the vibration damping effect of the vibration component is. The corrected hydraulic control command value is calculated by subtracting the correction amount from the hydraulic control command value, thereby suppressing fluctuations in the hydraulic control command value. Furthermore, by providing a wide frequency band for filtering, it is possible to stably respond to variable frequencies based on the gear ratio of the continuously variable transmission. Furthermore, if a sufficient vibration damping effect cannot be obtained by directly extracting the vibration component, an appropriate vibration damping effect can be obtained by adjusting the correction amount to an appropriate value.

1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating control functions and main parts of a control system for various controls in the vehicle. 4 is a flowchart showing a flow from a hydraulic control command value to a corrected hydraulic control command value; FIG. 3 is a diagram showing a control state based on FIG. 2 .

Embodiments of the present invention will now be described in detail with reference to the drawings. Please note that the drawings in the following embodiments have been simplified or modified as appropriate, and the dimensional proportions and shapes of each part are not necessarily drawn accurately.

Figure 1 is a diagram illustrating the general configuration of a vehicle 10 to which the present invention is applied, as well as a diagram illustrating the control functions and main parts of the control system for various controls in the vehicle 10. In Figure 1, the vehicle 10 is equipped with an engine 12 as a power source for driving, a torque converter 14, a forward/reverse switching device 16, a belt-type continuously variable transmission 18 (hereinafter referred to as the continuously variable transmission 18), a reduction gear device 20, a differential gear device 22, and a pair of left and right front wheels 24L, 24R.

The forward/reverse switching device 16 is primarily composed of a forward clutch C1, a reverse brake B1, and a double-pinion planetary gear unit 16p. Because the forward/reverse switching device 16 is publicly known, a detailed description of its structure and operation will be omitted.

The continuously variable transmission 18 includes an input-side primary pulley 26, which serves as an input member and has a variable effective diameter; an output-side secondary pulley 28, which serves as an output member and has a variable effective diameter; and a transmission belt 30 wound between the primary pulley 26 and the secondary pulley 28. The continuously variable transmission 18 transmits power via frictional forces between the primary pulley 26, the secondary pulley 28, and the transmission belt 30.

The input-side primary pulley 26 is equipped with a fixed sheave 26a as the input-side fixed rotor, a movable sheave 26b as the input-side movable rotor, and a hydraulic actuator (hydraulic cylinder) 26c that applies an input-side thrust (primary thrust) Wpri (= primary pressure Ppri x pressure-receiving area) to change the V-groove width between the fixed sheave 26a and the movable sheave 26b.

The output-side secondary pulley 28 includes a fixed sheave 28a as the output-side fixed rotor, a movable sheave 28b as the output-side movable rotor, and a hydraulic actuator 28c that applies a thrust (secondary thrust) Wsec (= secondary pressure Psec x pressure-receiving area) to change the V-groove width between the fixed sheave 28a and the movable sheave 28b.

In the continuously variable transmission 18, the primary pressure Ppri, which is the hydraulic pressure supplied to the hydraulic actuator 26c of the primary pulley 26, and the secondary pressure Psec, which is the hydraulic pressure supplied to the hydraulic actuator 28c of the secondary pulley 28, are each regulated and controlled by the hydraulic control circuit 40, thereby controlling the primary thrust Wpri and secondary thrust Wsec. As a result, by changing the V-groove widths of the primary pulley 26 and the secondary pulley 28, the gear ratio γcvt of the continuously variable transmission 18 can be continuously changed.

The vehicle 10 is equipped with an electronic control unit 50 for performing various controls, including shift control of the continuously variable transmission 18.

Various input signals based on the detected values obtained by various sensors (52, 54, 56, 58, 60, 62, etc.) provided on the vehicle 10 are input to the electronic control unit 50. For example, various signals representing the engine rotation speed Ne (rpm), turbine rotation speed Nt (rpm), input rotation speed Nin (rpm), output rotation speed Nout (rpm) corresponding to vehicle speed V (km/h), accelerator opening θacc (°), throttle valve opening θth (°), etc. are input.

The electronic control unit 50 outputs, for example, a command signal Se for controlling the engine output of the engine 12, a CVT hydraulic control command signal Scvt for hydraulic control related to gear changes in the continuously variable transmission 18, and a hydraulic control command signal Sc for hydraulic control related to the engagement operation of the forward clutch C1 and reverse brake B1.

The electronic control unit 50 is functionally equipped with an engine control unit for controlling the engine 12, a continuously variable transmission control unit for controlling the continuously variable transmission 18, and other components.

In a vehicle 10 equipped with the above-described continuously variable transmission 18, when torque fluctuations occurring at the powertrain's resonant frequency and hydraulic vibrations caused by the primary pressure Ppri and secondary pressure Psec influence each other and overlap, resulting in coupled vibrations, vehicle longitudinal vibrations can occur. In response to this, the electronic control unit 50 has the function of appropriately adjusting the command pressure for the primary pressure Ppri and the command pressure for the secondary pressure Psec to suppress hydraulic vibrations and thereby suppress vehicle longitudinal vibrations. In the following, the command pressure for the primary pressure Ppri and the command pressure for the secondary pressure Psec of the continuously variable transmission 18 will be collectively referred to as the hydraulic control command value Pindi for the continuously variable transmission 18.

The electronic control unit 50 functionally comprises a filter processing unit 80, a vibration component extraction unit 82, a correction amount calculation unit 84, and a command value correction unit 86, which are executed to suppress vehicle longitudinal vibration.

The filter processing unit 80 filters the hydraulic control command value Pindi to remove vibration components in a predetermined frequency band. For example, a band elimination filter or low-pass filter is applied to the hydraulic control command value Pindi to remove vibration components in a predetermined frequency band, resulting in the hydraulic control command value Pindi being a smoothed filtered value Pfilt. Here, the predetermined frequency band is determined in advance experimentally or by design, and is set, for example, to a band in which hydraulic vibrations occur (i.e., a resonant frequency band). Furthermore, since the resonant frequency of the continuously variable transmission 18 changes depending on the gear ratio γcvt, a wide band is set taking into account the gear ratio γcvt of the continuously variable transmission 18.

The vibration component extraction unit 82 subtracts the filtered value Pfilt from the hydraulic control command value Pindi to extract the vibration component Pvib (= Pindi - Pfilt).

The correction amount calculation unit 84 calculates the correction amount Pcrt based on PI control by applying a PI controller 88 to the vibration component Pvib. In PI control, FB control is performed to appropriately adjust the correction amount Pcrt based on the vibration component Pvib. Therefore, if, for example, the vibration damping effect is insufficient, the correction amount Pcrt is increased by PI control via the PI controller 88. In this way, the correction amount Pcrt is appropriately adjusted, thereby improving the vibration damping effect.

The command value correction unit 86 calculates the corrected hydraulic control command value Pindic by subtracting the correction amount Pcrt from the hydraulic control command value Pindi. This corrected hydraulic control command value Pindic is set as the new hydraulic control command value Pindi. By correcting the hydraulic control command value Pindi in this manner, hydraulic vibrations in the primary pressure Ppri and secondary pressure Psec are suppressed, and fluctuations in the command values of the primary pressure Ppri and secondary pressure Psec are suppressed. As a result, vehicle longitudinal vibrations caused by hydraulic vibrations are suppressed. Furthermore, in the continuously variable transmission 18, the resonance frequency changes depending on the gear ratio γcvt, but by setting a wide frequency band for filtering, it is possible to stably respond to variable resonance frequencies.

Figure 2 is a flowchart showing the process for calculating the corrected hydraulic control command value Pindic from the hydraulic control command value Pindi. Figure 3 is a diagram showing the control state based on Figure 2.

In FIG. 2, first, when the hydraulic control command value Pindi is given, filtering is performed. For example, as shown in FIG. 2, filtering is performed, such as reducing the gain G in a predetermined frequency band, thereby removing vibration components in the predetermined frequency band and calculating the filtered value Pfilt. This state corresponds to the states in FIGS. 3(a) to 3(c). Next, the filtered value Pfilt is subtracted from the hydraulic control command value Pindi to extract the vibration component Pvib, and PI control is performed on the vibration component Pvib by the PI controller 88 to calculate the post-PI control correction amount Pcrt. Next, the correction amount Pcrt is subtracted from the hydraulic control command value Pindi to calculate the corrected hydraulic control command value Pindic. This state corresponds to the states in FIGS. 3(d) to 3(f). In FIG. 3(f), the dashed line corresponds to the corrected hydraulic control command value Pindic. As shown by the dashed line in Figure 3(f), for example, by providing a command value in the opposite phase to the hydraulic control command value Pindi in Figure 3(a), hydraulic vibrations in the primary pressure Ppri and secondary pressure Psec are suppressed. As a result, vehicle fore-and-aft vibrations are suppressed.

As described above, according to this embodiment, the hydraulic control command value Pindi is filtered, and the correction amount Pcrt is calculated based on the vibration component Pvib extracted by subtracting the filtered value Pfilt (calculated value) from the hydraulic control command value Pindi. The corrected hydraulic control command value Pindic is calculated by subtracting the correction amount Pcrt from the hydraulic control command value Pindi, thereby suppressing fluctuations in the hydraulic control command value Pindi. Furthermore, by using a wide frequency band for filtering, it is possible to stably respond to variable frequencies based on the gear ratio γcvt of the continuously variable transmission 18. Furthermore, if extracting the direct vibration component Pvib does not provide a sufficient vibration damping effect, the PI controller 88 appropriately adjusts the correction amount Pcrt, thereby improving the vibration damping effect.

Please note that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

18: Continuously variable transmission 50: Electronic control unit (controller) 80: Filter processing unit 82: Vibration component extraction unit 84: Correction amount calculation unit 86: Command value correction unit

Claims (1)

A control device for a vehicle having a continuously variable transmission capable of continuously changing a gear ratio,
a filter processing unit that filters a hydraulic control command value of the continuously variable transmission;
a vibration component extraction unit that extracts a vibration component by subtracting the calculated value after the filter processing from the hydraulic control command value;
a correction amount calculation unit that calculates a correction amount of the hydraulic control command value based on the vibration component so that the correction amount becomes larger as the vibration damping effect of the vibration component becomes insufficient ;
a command value correcting unit that calculates a corrected hydraulic control command value by subtracting the correction amount from the hydraulic control command value.