초록 ▼

Control device for a 4WD vehicle is provided. The 4WD vehicle includes a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism. The first disconnection mechanism and the second di

Control device for a 4WD vehicle is provided. The 4WD vehicle includes a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism. The first disconnection mechanism and the second disconnection mechanism are engaged during 4WD traveling. One of the first disconnection mechanism and the second disconnection mechanism is a clutch. The control device includes an electronic control unit. The electronic control unit is configured to execute engagement control for controlling the engagement force of the clutch so that the driving force transmission shaft is maintained in a state prior to the initiation of a continuous increase in the rotation speed of the driving force transmission shaft.

대표청구항 ▼

1. A control device for a 4WD vehicle, the 4WD vehicle including a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism, the driving force transmission shaft configured to transm

1. A control device for a 4WD vehicle, the 4WD vehicle including a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism, the driving force transmission shaft configured to transmit part of power of the driving force source transmitted to the main driving wheels to the auxiliary driving wheels during 4WD traveling, the first disconnection mechanism disposed on the driving force source side of the driving force transmission shaft, the second disconnection mechanism disposed on the auxiliary driving wheels side of the driving force transmission shaft, the first disconnection mechanism and the second disconnection mechanism being configured to disconnect a power transmission path between the driving force source and the auxiliary driving wheels, the 4WD traveling being traveling with the first disconnection mechanism and the second disconnection mechanism being engaged, one of the first disconnection mechanism and the second disconnection mechanism being a clutch, the clutch having a first rotating member and a second rotating member configured to rotate relative to the first rotating member, and the clutch being configured to control an engagement force while synchronizing a rotation speed of the first rotating member and a rotation speed of the second rotating member, the control device comprising: an electronic control unit configured to:execute engagement control for controlling the engagement force of the clutch such that the driving force transmission shaft is maintained in a state prior to an initiation of a continuous increase in the rotation speed of the driving force transmission shaft, andcontrol the engagement force of the clutch based on a temperature of a hydraulic oil at the initiation of the engagement control, the hydraulic oil lubricates at least the first rotating member or the second rotating member, and the clutch is configured to cause an increase of the rotation speed of the first rotating member or the rotation speed of the second rotating member as a result of the engagement of the clutch. 2. The control device according to claim 1, wherein the electronic control unit is configured to: increase the engagement force in executing the engagement control continuously or in stages; andhold the engagement force at a first value after the initiation of the increase in the rotation speed of the driving force transmission shaft, the first value is lower by a predetermined value than a value of the engagement force at the initiation of the increase in the rotation speed of the driving force transmission shaft. 3. The control device according to claim 2, wherein the electronic control unit is configured to control the engagement force at the first value at an initiation of a subsequent engagement control. 4. A control device for a 4WD vehicle, the 4WD vehicle including a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism, the driving force transmission shaft configured to transmit part of power of the driving force source transmitted to the main driving wheels to the auxiliary driving wheels during 4WD traveling, the first disconnection mechanism disposed on the driving force source side of the driving force transmission shaft, the second disconnection mechanism disposed on the auxiliary driving wheels side of the driving force transmission shaft, the first disconnection mechanism and the second disconnection mechanism being configured to disconnect a power transmission path between the driving force source and the auxiliary driving wheels, the 4WD traveling being traveling with the first disconnection mechanism and the second disconnection mechanism being engaged, one of the first disconnection mechanism and the second disconnection mechanism being a clutch, the clutch having a first rotating member and a second rotating member configured to rotate relative to the first rotating member, and the clutch being configured to control an engagement force while synchronizing a rotation speed of the first rotating member and a rotation speed of the second rotating member, the control device comprising: an electronic control unit configured to:determine whether or not to perform a transition to the 4WD traveling during 2WD traveling, the 2WD traveling being traveling with the first disconnection mechanism and the second disconnection mechanism being released,determine whether or not the 4WD vehicle is in a predetermined traveling state when the transition to the 4WD traveling is not determined,execute engagement control for controlling the engagement force of the clutch such that the driving force transmission shaft is maintained in a state prior to an initiation of a continuous increase in the rotation speed of the driving force transmission shaft in a case where the electronic control unit determines that the 4WD vehicle is in the predetermined traveling state,determine that the 4WD vehicle is in the predetermined traveling state (i) when the electronic control unit predicts that a predetermined vehicle wheel speed difference occurs between the main driving wheels and the auxiliary driving wheels or (ii) when the electronic control unit predicts that an understeer state or an oversteer state occurs during the 2WD traveling,increase the engagement force in executing the engagement control continuously or in stages; andhold the engagement force at a first value after the initiation of the increase in the rotation speed of the driving force transmission shaft, the first value is lower by a predetermined value than a value of the engagement force at the initiation of the increase in the rotation speed of the driving force transmission shaft. 5. The control device according to claim 4, wherein the electronic control unit is configured to predict whether or not the predetermined vehicle wheel speed difference occurs or predict whether or not any one of the understeer state and the oversteer state occurs based on at least one of states of a low μ road, an uphill road, or steering. 6. The control device according to claim 4, wherein the electronic control unit is configured to: determine, during the 2WD traveling, whether or not to perform the transition to the 4WD traveling by (i) the electronic control unit determining whether or not a predetermined vehicle wheel speed difference occurs between the main driving wheels and the auxiliary driving wheels or (ii) the electronic control unit determining whether or not any one of an understeer state and an oversteer state occurs, andincrease the engagement force in executing the engagement control such that the clutch is engaged in a case where the electronic control unit determines the transition to the 4WD traveling. 7. The control device according to claim 4, wherein the electronic control unit is configured to control the engagement force at the first value at an initiation of a subsequent engagement control. 8. A control device for a 4WD vehicle, the 4WD vehicle including a driving force source, main driving wheels, auxiliary driving wheels, an automatic transmission, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism, the automatic transmission disposed in a power transmission path between the driving force source and the main driving wheels, the driving force transmission shaft configured to transmit part of power of the driving force source transmitted to the main driving wheels to the auxiliary driving wheels during 4WD traveling, the first disconnection mechanism disposed on the driving force source side of the driving force transmission shaft, the second disconnection mechanism disposed on the auxiliary driving wheels side of the driving force transmission shaft, the first disconnection mechanism and the second disconnection mechanism being configured to disconnect a power transmission path between the driving force source and the auxiliary driving wheels, the 4WD traveling being traveling with the first disconnection mechanism and the second disconnection mechanism being engaged, one of the first disconnection mechanism and the second disconnection mechanism being a clutch, the clutch having a first rotating member and a second rotating member configured to rotate relative to the first rotating member, and the clutch being configured to control an engagement force while synchronizing a rotation speed of the first rotating member and a rotation speed of the second rotating member, the control device comprising: an electronic control unit configured to:execute engagement control for controlling the engagement force of the clutch such that the driving force transmission shaft is maintained in a state prior to an initiation of a continuous increase in the rotation speed of the driving force transmission shaft,determine whether or not to perform a transition to the 4WD traveling during 2WD traveling, the 2WD traveling being traveling with the first disconnection mechanism and the second disconnection mechanism being released,determine whether or not the 4WD vehicle is in a predetermined traveling state when the transition to the 4WD traveling is not determined, andexecute the engagement control in a case where the electronic control unit determines that the 4WD vehicle is in the predetermined traveling state,wherein the electronic control unit is configured to determine, during the 2WD traveling, that the 4WD vehicle is in the predetermined traveling state when a manual transmission device is operated by a driver or when a snow mode is selected by a mode selection device being operated by the driver, the manual transmission device being configured to manually shift the automatic transmission, and the mode selection device having a predetermined normal mode and a predetermined snow mode in which a gear ratio on a high vehicle speed side of the automatic transmission is likely to be selected compared to the predetermined normal mode. 9. The control device according to claim 8, wherein the electronic control unit is configured to: determine, during the 2WD traveling, whether or not to perform the transition to the 4WD traveling by determining whether or not the shift of the automatic transmission is initiated in a case where the electronic control unit determines that the 4WD vehicle is in the predetermined traveling state by the operation being performed by the driver, andincrease the engagement force in executing the engagement control such that the clutch is engaged in a case where the electronic control unit determines the transition to the 4WD traveling by determining that the shift of the automatic transmission is initiated. 10. The control device according to claim 8, wherein the electronic control unit is configured to control the engagement force of the clutch based on a temperature of a hydraulic oil at the initiation of the engagement control, the hydraulic oil lubricates at least the first rotating member or the second rotating member, and the clutch is configured to cause an increase of the rotation speed of the first rotating member or the rotation speed of the second rotating member as a result of the engagement of the clutch. 11. The control device according to claim 8, wherein the electronic control unit is configured to: increase the engagement force in executing the engagement control continuously or in stages; andhold the engagement force at a first value after the initiation of the increase in the rotation speed of the driving force transmission shaft, the first value is lower by a predetermined value than a value of the engagement force at the initiation of the increase in the rotation speed of the driving force transmission shaft. 12. The control device according to claim 11, wherein the electronic control unit is configured to control the engagement force at the first value at an initiation of a subsequent engagement control.