JP2007246056A - Drive controller of all-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively transfer torque to front and rear wheels by adding a motor generator for torque transfer to a center differential that is capable of freely setting reference torque distribution ratio to the front and rear wheels and to perform driving force control that makes effective use of the motor generator for torque transfer. <P>SOLUTION: This drive controller, which controls the driving force distribution ratio to the front and rear wheels by means of the added torque of a second motor generator 5 to a center differential 10 and to driving force distribution changing mechanisms 21-24, includes an electronic control unit 40 for controlling activation of drive sources 1 (engine 1A and first motor generator 1B) and the second motor generator 5 and for controlling a differential limiting clutch 4 to be either engaged or disengaged. With the drive source 1 stopped, the electronic control unit 40 engages the differential limiting clutch 4 and controls the additional driving force of the second motor generator 5, thereby setting drive from an idle stop as EV drive that uses only the second motor generator 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive control device for distributing driving force to front and rear wheels of an all-wheel drive (AWD) vehicle.

  In general, an all-wheel drive vehicle is provided with a center differential device at the rear stage of the transmission in order to provide a differential function for absorbing a difference in rotational speed generated between the front and rear wheels. This center differential device has been proposed to employ a compound planetary gear mechanism. According to this, the reference torque distribution distributed to the front and rear wheels can be arbitrarily changed by changing various specifications of the compound planetary gear mechanism. It becomes possible to set. In addition, a hydraulic multi-plate clutch is used as a differential limiting device for the center differential device, and the differential limiting torque of the hydraulic multi-plate clutch is variably controlled using a hydraulic control system for automatic transmission or a microcomputer, thereby limiting the differential. A drive control device that controls the torque distribution of the front and rear wheels by adjusting the degree of the above is also conventionally known.

  An example of this prior art (see Patent Document 1 below) will be described with reference to FIG. 1A. A center differential device 100 and a hydraulic multi-plate clutch 120 are provided at the rear stage of an automatic transmission (not shown). The center differential device 100 includes a first sun gear 102 formed on the transmission output shaft 101 and a second intermediate shaft 104 among the first intermediate shaft 103 and the second intermediate shaft 104 arranged coaxially with the transmission output shaft 101. The first and second pinions 107 and 108 supported by the carrier 106 are arranged around the first sun gear 102 and the second sun gear 105. The first intermediate shaft 103 is loosely fitted inside the second intermediate shaft 104 and is connected to the carrier 106 by a connecting member 109.

  As a result, the driving force input to the first sun gear 102 is transmitted to the carrier 106 and the second sun gear 105 at a reference torque distribution ratio according to the gear specifications of the compound planetary gear mechanism, and is not shown through the reduction gear 110 from the carrier 106. The driving force is transmitted from the second sun gear 104 to the rear drive shaft 111 via a hydraulic multi-plate clutch 120 described later. In addition, a differential mechanism is formed that absorbs the rotational speed difference between the carrier 106 and the second sun gear 105 caused by the differential rotation of the front and rear wheels by the planetary rotation of the first and second pinions 107 and 108.

  In the hydraulic multi-plate clutch 120, a first clutch portion 121 as a frictional engagement element for torque transmission is interposed between the second intermediate shaft 104 and the rear drive shaft 111, and the first intermediate shaft 103 And a rear drive shaft 111 are provided with a second clutch portion 122 as a friction engagement element for differential restriction and torque movement. Furthermore, the second intermediate shaft 104 is provided with an overdrive brake portion 123 as a friction engagement element that blocks the differential function of the center differential device 100 and rotates the carrier 106 at a higher speed.

The torque distribution function in the prior art will be described. The reference torque distribution by the center differential device 100 is that the input torque of the first sun gear 102 is Ti, the front side torque of the carrier 106 is Tf, and the rear side torque of the second sun gear 105. Tr, α = Z _s1 / Z _p1 (Z _s1 : number of teeth of first sun gear 102, Z _p1 : number of teeth of first pinion 107), β = Z _s2 / Z _p2 (Z _s2 : of second sun gear 105 Assuming that the number of teeth, Z _p2 : the number of teeth of the second pinion 108), the following equations (1-1) and (1-2) are obtained.

  That is, in this prior art, the reference torque distribution ratio Tf: Tr of the front side torque Tf and the rear side torque Tr is the number of gear teeth of the first and second sun gears 102 and 105 and the first and second pinions 107 and 108. Can be set freely by appropriately changing. Then, with respect to the set reference torque distribution ratio Tf: Tr, the second clutch portion 122 is variably engaged and controlled to generate a differential limiting torque. It is possible to arbitrarily change the torque distribution ratio in a range up to the torque distribution ratio (corresponding to load distribution of the front and rear wheels) in the differential lock state in which the second sun gear 104 and the carrier 106 are directly connected.

  In this prior art, the reference torque distribution ratio (for example, Tf: Tr = 45: 55) set by the compound planetary gear mechanism of the center differential device reaches the torque distribution ratio (for example, 50:50) of the directly connected four-wheel drive. It is possible to change the driving force distribution of the front and rear wheels within the range, but in the case of normal traveling straight ahead, it is said that the driving force distribution of the front wheel bias is more preferable for ensuring stable traveling, In order to enhance the driving performance of the vehicle in response to various conditions, as described above, it is said that the driving force distribution of the rear wheel bias is more preferable in securing the start / acceleration performance at the time of acceleration such as starting, etc. Therefore, the driving force distribution control of the front and rear wheels exceeding the range is required.

  Therefore, in order to cope with this, the prior art described in Patent Document 2 below is proposed. According to this, with respect to the center differential device described above, a motor torque adding mechanism is provided that makes the torque distribution ratio distributed from each output element to the front and rear wheels variable by adding an electric motor torque between the output elements. By variably controlling the addition of the motor torque, it is possible to change the torque distribution ratio in a wide range exceeding the change range in Patent Document 1 described above.

Japanese Patent No. 2603879 JP 2005-90648 A

  The prior art disclosed in Patent Document 2 will be described with reference to FIG. 1B. The center differential 10 has a compound planetary gear mechanism as a basic configuration, and includes a first sun gear 11, a first sun gear 11, A second sun gear 12 that is coaxially disposed, a first pinion 13 that is disposed around the first and second sun gears 11 and 12 and meshes with the first sun gear, and a second sun gear that is formed integrally with the first pinion 13. The first sun gear 11 is used as one input element that receives a driving force from a driving source of the vehicle, and the second sun gear 12 is provided on one of the front and rear wheels of the vehicle. The first output element that transmits the driving force is used, and the carrier 15 that supports the first and second pinions 13 and 14 is the second output element that transmits the driving force to the other of the front and rear wheels of the vehicle. , And it outputs the respective output elements described above with reference torque distribution ratio set the input driving force.

  On the other hand, the motor torque adding mechanism 20 is provided between the first output element and the second output element of the center differential 10 and is moved forward and backward from each output element of the center differential 10 by applying the electric motor torque. The torque distribution ratio distributed to the wheels is variable.

  The configuration will be specifically described. A pinion (first transmission element) 22 rotatably supported by a coupling element 24 coupled to the second sun gear 12 which is a first output element of the center differential 10, and the center differential The ring gear 23 (second transmission element) that is coupled to the carrier 15 as the second output element 10 and engages with the pinion 22 and the first and second sun gears 11 and 12 of the center differential 10 are arranged coaxially. A planetary gear mechanism including a sun gear 21 is provided. An electric motor 25 for adding electric motor torque to the sun gear 21 is connected. In the example of FIG. 1B, the rotor 25A of the electric motor 25 is provided coaxially with the sun gear 21, the rotor 25A is directly connected to the sun gear 21 via the connecting shaft 26, and the stator 25B is provided coaxially with the rotor 25A. is doing.

  According to this, when the driving force from the driving source of the vehicle is input to the first sun gear 11 which is one input element of the center differential 10 via the input shaft 30, it is the first output element of the center differential 10. A driving force is transmitted from the first output shaft 31 coupled to the pinion 22 of the motor torque adding mechanism 20 via the second sun gear 12 and the coupling member 24 to one of the front and rear wheels of the vehicle (at this time, the coupling shaft 26 Becomes a hollow shaft and is loosely fitted in the connecting shaft 26 to provide the first output shaft 31.) A reduction gear 33A coupled to the carrier 15 which is the second output element of the center differential 10. , 33B, the driving force is transmitted from the second output shaft 32 connected to the other of the front and rear wheels of the vehicle.

  The motor torque adding mechanism 20 has a function of taking the torque flowing from one output element in the center differential 10 to one of the front and rear wheels and flowing it to the other output element of the center differential 10 according to the amount of electric motor torque added. Thus, regardless of the differential function of the center differential 10, the torque distribution ratio of the front and rear wheels can be changed in a wide range according to the added amount of electric motor torque.

  However, in the prior art shown in FIG. 1B, an electric motor serving as a new drive source is provided in order to change the torque distribution ratio of the front and rear wheels. Although it contributes to changing the torque distribution ratio, it is difficult to say that it is effectively utilized as a new added drive source.

  Moreover, in this prior art, since the two output elements of the center differential 10 cannot be directly connected, the wheel driving force on the non-slip side is lost when the front wheel or the rear wheel slips, and the traction performance deteriorates. Problems arise.

  Furthermore, according to this prior art, when the electric motor torque is applied in the forward direction or the reverse direction with respect to the input torque in order to change the torque distribution ratio of the front and rear wheels, the total vehicle driving force is increased or decreased. Become. In addition to the change in the torque distribution ratio of the front and rear wheels, the total driving force may need to be increased, decreased, or constant. In addition to the simple request to change the torque distribution ratio of the front and rear wheels, There is a problem that it is not possible to cope with driving force control that requires high steering stability.

  In general, the driving force from the driving source is distributed to the front and rear wheels via a torque converter and a transmission, but when the torque converter is unlocked, the regenerative braking torque transmitted from the front and rear wheels is torque. There is a problem that the regenerative efficiency of the starter / generator connected to the drive source is reduced by being absorbed by the converter.

  The present invention has been proposed to cope with such a problem, and a motor generator for torque transfer is provided for a center differential capable of setting a free reference torque distribution ratio of front and rear wheels. By adding, it is possible to actively move the torque to the front and rear wheels beyond the range from the reference torque distribution ratio to zero differential rotation, and improve the traction performance when the front or rear wheel slips , Improve the running performance of all-wheel drive vehicles, further improve the running performance at start-up and adjustment, etc., by effectively using the motor generator for torque transfer as an additional drive source, torque transfer By controlling the increase / decrease in the total driving force of the vehicle against the addition of the driving force by the motor generator for the vehicle, it is possible to support the driving force control that requires high steering stability, In which performs driving force distribution to front and rear wheels via a converter, it is possible to obtain a high regeneration efficiency even when the lock-up opening, etc. It is an object of the present invention.

  In order to achieve such an object, one aspect of the present invention is a drive control device for controlling the driving force distributed to the front and rear wheels, wherein the first motor generator is connected to the engine output shaft. A power source, one input element to which the driving force from the driving source is input, and two output elements for transmitting the driving force to the front and rear wheels of the vehicle, respectively, and one of the input element and the output element is coaxially arranged. A center differential that outputs the input driving force to each of the output elements at a set reference torque distribution ratio, a differential limiting clutch that fastens and synchronizes the output elements, and each of the outputs A driving force distribution changing mechanism for changing a distribution ratio of the driving force transmitted from the output elements to the front and rear wheels by adding a driving force between the elements, and a second motor generator coupled to the driving force distribution changing mechanism And the drive source and the front Control means for controlling operation of the second motor generator and engagement / non-engagement of the differential limiting clutch, and the control means engages the differential limiting clutch with the drive source stopped. The additional driving force of the second motor generator is controlled.

  Further, in the drive control device described above, the center differential includes a first sun gear, a second sun gear arranged coaxially with the first sun gear, and the first and second sun gears. A first pinion that meshes with the first sun gear; and a second pinion that is integrally formed with the first pinion and meshes with the second sun gear, wherein the first sun gear is the input element, and the second sun gear is A first output element that transmits driving force to either one of the front and rear wheels is used, and a support member that supports the first and second pinions is a second output element that transmits driving force to the other front or rear wheel of the vehicle. The driving force distribution changing mechanism is coaxial with the first transmission element coupled to the first output element, the second transmission element coupled to the second output element, and the first and second sun gears. Placed on Comprising a planetary gear mechanism comprising a sun gear, the said sun gear second motor generator, characterized in that it is connected.

  Alternatively, in the drive control device described above, the control means detects that the brake has been released from a state where the brake is operated and the vehicle is stopped and the drive source is stopped. When the state of charge of the battery that supplies power to the motor generator is good, the vehicle is driven by the additional driving force of the second motor generator, and when the state of charge of the battery is poor, the drive source It is characterized by performing normal running by restarting.

  Alternatively, in the drive control device described above, the control means obtains an estimated output driving force and a target front-rear driving force distribution ratio of the drive source in a current traveling state, and calculates a front-rear wheel driving force distribution ratio of the vehicle. In the process of obtaining the additional driving force of the second motor generator necessary to achieve the target longitudinal driving force distribution ratio, the power generation drive according to the increase in the total driving force due to the additional driving force of the second motor generator The first motor generator is regeneratively operated so as to apply a force.

  Alternatively, in the drive control device described above, the control means obtains an estimated output driving force and a target front-rear driving force distribution ratio of the drive source in a current traveling state, and calculates a front-rear wheel driving force distribution ratio of the vehicle. In the process of obtaining the additional driving force of the second motor generator necessary for obtaining the target longitudinal driving force distribution ratio, the power generation driving force by the first motor generator is reduced, and the target longitudinal driving force distribution ratio is obtained. In this case, the additional driving force of the second motor generator necessary for achieving the above is obtained again.

  Moreover, in the drive control device described above, the control unit changes the target front / rear driving force distribution ratio and the front / rear wheel driving force distribution ratio of the vehicle according to the selected travel mode. It is characterized in that an additional driving force of the second motor generator necessary for obtaining a target longitudinal driving force distribution ratio is obtained.

  Further, in the drive control device described above, the driving force from the drive source is output via a torque converter with a lock-up clutch, and the control means is configured to perform the lock-up clutch during regenerative braking. When is opened, the differential limiting clutch is engaged to regenerate the second motor generator.

  In the present invention having such characteristics, the torque distribution ratio of the front and rear wheels can be changed in a wide range by controlling the additional driving force of the second motor generator with respect to the reference torque distribution ratio of the center differential. become. Further, by controlling the additional driving force of the second motor generator by engaging the differential limiting clutch while the drive source is stopped by the control means described above, for example, the second motor generator during idle stop It is possible to perform electric driving that drives only the vehicle, and fuel efficiency can be improved by combining with various energy management controls. Furthermore, since the second motor generator can be electrically driven with the driving force transmitted from the driving source blocked by the main clutch, a shock due to the engine driving force at the time of engine restart in the idle stop control is directly applied to the output shaft. There is no transmission and smooth engine restart can be performed. Furthermore, if necessary, the differential limiting clutch can be engaged to establish a direct connection AWD, so that the traction performance during front wheel or rear wheel slip is improved.

  A first sun gear; a second sun gear disposed coaxially with the first sun gear; a first pinion meshing with the first sun gear around the first and second sun gears; and the first pinion; A second pinion that is integrally formed and meshes with the second sun gear, wherein the first sun gear is one input element that receives a driving force from a driving source of the vehicle, and the second sun gear is one of the front and rear wheels of the vehicle. With respect to a center differential provided with a first output element that transmits driving force to one of them and a second output element that supports the first and second pinions and transmits driving force to the other of the front and rear wheels of the vehicle. Since a driving force distribution mechanism for applying torque is provided between the output elements, the reference number can be set by appropriately setting the number of gear teeth of the first and second sun gears and the first and second pinions. Torque distribution ratio It can be set to reason. When torque addition by the second motor generator is not performed, the reference torque distribution ratio set by the center differential is obtained, so that all-wheel drive with low power consumption and full time without always driving the second motor generator. Can be realized. Further, since pure electric front and rear wheel torque distribution control is possible, a system with high applicability to a hybrid vehicle or an electric vehicle can be constructed.

  Further, as the driving force distribution changing mechanism, the first transmission element coupled to the first output element in the center differential, the second transmission element coupled to the second output element, and coaxial with the first and second sun gears. The planetary gear mechanism consisting of the sun gear arranged on the planetary gear mechanism is used to add torque to the sun gear of this planetary gear mechanism, so the torque added by the amplifying action of the planetary gear mechanism is amplified to assist the output of the center differential. can do. As a result, the torque distribution ratio of the front and rear wheels can be effectively changed with a small torque addition, and the second motor generator can be downsized. In addition, since the sun gear of the driving force distribution changing mechanism that rotates constantly is not exposed on the surface of the mechanism, an apparatus that can be easily installed in the vehicle can be obtained even in consideration of interference with peripheral equipment.

  In addition, the control by the control means described above is performed by detecting that the brake is released from the state where the vehicle brake is operated and the drive source is stopped, and the state of charge of the battery that supplies power to the second motor generator is detected. If the battery is in good condition, the vehicle is driven by the additional driving force of the second motor-generator, and if the battery is not fully charged, normal driving is performed by restarting the drive source. Accordingly, it is possible to select electric traveling or engine restart traveling. As a result, fuel efficiency can be improved by electric travel, and battery depletion can be prevented.

  Further, in the control by the control means described above, in order to obtain the estimated output driving force of the driving source and the target front / rear driving force distribution ratio in the current traveling state, and to set the front / rear wheel driving force distribution ratio of the vehicle to the target front / rear driving force distribution ratio. In the process of obtaining the additional driving force of the second motor generator necessary for the first motor generator, the first motor generator is added so that the power generation driving force corresponding to the increase in the total driving force by the additional driving force of the second motor generator is added. By using the regenerative operation of the front and rear wheels, the increase in the total driving force of the vehicle due to the driving force distribution control is utilized for the regenerative torque of the first motor generator, preventing the increase in the total driving force of the vehicle, and without energy loss. Wheel driving force distribution control can be performed. This makes it possible to perform control to keep the total driving force constant while performing driving force distribution control of the front and rear wheels.

  Further, in the control by the control means described above, in order to obtain the estimated output driving force of the driving source and the target front / rear driving force distribution ratio in the current traveling state, and to set the front / rear wheel driving force distribution ratio of the vehicle to the target front / rear driving force distribution ratio. In the process of obtaining the additional driving force of the second motor generator required for the second motor generator, the second motor generator is added to reduce the power generation driving force by the first motor generator and achieve the target longitudinal driving force distribution ratio. By obtaining the driving force again, for example, it becomes possible to amplify the total vehicle driving force in response to an acceleration request.

  Further, in the control by the control means described above, the target front / rear driving force distribution ratio is changed according to the selected travel mode, so that the front / rear wheel driving force distribution ratio of the vehicle is changed to the changed target front / rear driving force distribution ratio. By calculating the additional driving force of the second motor generator required for driving, for example, when driving in the city, select a mode that emphasizes fuel consumption and set the target driving force distribution ratio to improve fuel consumption, and drive on mountain roads with many corners In the middle, it is possible to select a mode emphasizing athletic performance and achieve a target driving force distribution ratio aiming at improving athletic performance. As a result, vehicle characteristics that meet the driver's requirements can be provided.

  Further, in the control by the control means described above, when the driving force from the drive source is output via a torque converter with a lockup clutch, the control means is in the case where the lockup clutch is released during regenerative braking. In this case, by engaging the differential limiting clutch and regenerating the second motor generator, high regeneration efficiency is realized by regeneration by the second motor generator without using the torque converter when the lockup clutch is released. be able to.

  According to the present invention having such a feature, a reference torque distribution ratio can be obtained by adding a motor generator for torque movement to a center differential capable of setting a free reference torque distribution ratio for front and rear wheels. This enables aggressive torque transfer to the front and rear wheels beyond the range from zero to zero differential rotation, and improves traction performance during front or rear wheel slip, improving the driving performance of all-wheel drive vehicles can do.

  Further, by effectively utilizing the motor generator for moving the torque as an addition of the drive source, it is possible to further improve the running performance at the time of starting and adjusting. Further, by controlling the increase / decrease of the total vehicle driving force with respect to the addition of the driving force by the motor generator for torque movement, it is possible to cope with driving force control that requires high steering stability. Further, in the case where the driving force is distributed from the driving source to the front and rear wheels via the torque converter, high regeneration efficiency can be obtained even when the lockup is released.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is an explanatory diagram showing the overall configuration of the drive control apparatus for an all-wheel drive vehicle according to the embodiment of the present invention. A drive source 1 is constituted by the engine 1A and the first motor generator 1B connected to the output shaft. The first motor generator 1B includes a starter / generator or a motor / generator for performing torque assist and EV travel (electric travel) during travel.

  A transmission system is configured to transmit driving force from the driving source 1 to the center differential 10 via the torque converter 2 and the transmission 3. Here, the combination of the torque converter 2 and the transmission 3 is illustrated, but instead of this, a transmission mechanism including, for example, an electromagnetic clutch and a CVT mechanism may be provided. In the illustrated example, the torque converter 2 includes a lock-up clutch 2A. The differential limiting clutch 4 is provided in the subsequent stage of the center differential 10, and the motor torque adding mechanism 20 is further provided in the subsequent stage.

  The center differential 10 is the same as that shown in FIG. 1 (a), and the same reference numerals are given and repeated description is omitted. However, the center differential 10 is connected to the input shaft 30 from the vehicle drive source 1 via the torque converter 2 and the transmission 3. The input driving force is output to two output elements (second sun gear 12, carrier 15) with a set reference torque distribution ratio. The second sun gear 12, which is the first output element, is supplied to the vehicle. A first output shaft 31 to which driving force is transmitted is directly connected to one of the front and rear wheels, and the driving force is transmitted to the other front and rear wheels of the vehicle via the reduction gears 33A and 33B to the carrier 15 as the second output element. A second output shaft 32 to be transmitted is coupled.

  The differential limiting clutch 4 can be engaged and rotationally synchronized between the output elements (second sun gear 12 and carrier 15) of the center differential 10. Here, the second sun gear 12 and carrier 15 are engaged when engaged. The first output shaft 31 is integrated and rotated synchronously.

  The motor torque adding mechanism 20 is the same as that shown in FIG. 1B, and the overlapping portions are denoted by the same reference numerals and a part of the description is omitted, but the sun gear 21, pinion (first transmission element) is omitted. ) 22, a ring gear 23 (second transmission element), a driving force distribution changing mechanism 20A that forms a planetary gear mechanism by the coupling member 24, and a second motor generator 5 connected to the sun gear 21 via a connecting shaft 26. It is equipped with.

  As the power transmission system of the first motor generator 1B and the second motor generator 5, the first motor generator 1B is connected to the first battery 9A having a DC voltage of 12V, for example, via the first inverter 6 and the DC / DC converter 8. The second motor generator 5 is connected to the second battery 9 </ b> B via the second inverter 7. Further, the second battery 9B and the first battery 9A are connected via the DC / DC converter 8 to form the battery 9, and a 12V system vehicle harness is connected to the first battery 9A.

  Further, the electronic control system will be described. The electronic control unit (control means) 40 operates the drive source 1 (engine 1A, first motor generator 1B) and second motor generator 5, and the differential limiting clutch 4. This is for controlling the engagement / non-engagement, and further, the engagement / non-engagement of the lock-up clutch 2A as required, and also sends control signals to the first inverter 6 and the second inverter 7.

  The electronic control unit 40 outputs a control signal in accordance with a detection signal from the detection unit 41 made up of various sensors or a selection signal from the travel mode switch 42, and executes various controls described below. The detection unit 41 detects a vehicle running state and the like. For example, as illustrated, a wheel speed sensor 41A for detecting a wheel speed, an accelerator opening sensor 41B, and a brake sensor for detecting operation / release of a brake. 41C, front / rear G sensor 41D for detecting front / rear G, lateral G sensor 41E for detecting lateral G, yaw rate sensor 41F, battery sensor 41G for detecting battery SOC value or battery voltage.

In the drive control apparatus having such a system configuration, first, a basic driving force distribution function will be described. Here, the first output shaft 31 is a rear drive shaft that transmits driving force to the rear wheel side, and the second output shaft 32 is a front drive shaft that transmits power to the front wheel side. The input torque T _i is the input torque, the rear drive torque T _R is the torque output from the first output shaft 31, and the front drive torque T _F is the torque output from the second output shaft 32. illustrating the torque inputted to the sun gear 21 of the drive force distribution changing mechanism 20A from the generator 5 as an additional torque T _m.

FIG. 3 is an explanatory diagram for explaining a driving force distribution function using an additional torque. In the same figure, (a) is a figure which shows the balance state of the torque in the center differential 10, (b) is a figure which shows the balance state of the torque in the motor torque addition mechanism 20. According to this, first, in the center differential 10, the input torque T _i is taken out from the second sun gear 12 that is the first output element according to the equations (1-1) and (1-2) described in the prior art. The rear wheel side reference torque Tr and the front wheel side reference torque Tf taken out from the carrier 15 as the second output element are distributed. Here, as explained in the prior art, α = Z _s1 / Z _p1 (Z _s1 : number of teeth of the first sun gear 11, Z _p1 : number of teeth of the first pinion 13), β = Z _s2 / Z _p2 ( If Z _{s2 is} the number of teeth of the second sun gear 12 and Z _{p2 is the} number of teeth of the second pinion 14), the reference torque Tf on the front wheel side and the reference torque Tr on the rear wheel side are directly expressed by the equations (1-1) and ( 1-2).

Then, the reference torque Tf, relative Tr, the additional torque T _m acts, assist torque Tmf shown in (b) by the action of the drive force distribution changing mechanism 20A (planetary gear mechanism) in the motor torque application mechanism 20 , will be Tmr is synthesized in reference torque Tf, Tr respectively, the synthesized torque will be output as the front drive torque T _F and the rear drive torque T _R. Therefore, the front drive torque T _F and the rear drive torque T _R distributed and output to the front and rear wheels by the additional torque T _m are γ = Z _SUNm / Z _RINGm (Z _SUNm : number of teeth of the sun gear 21, Z _RINGm : ring gear 23), the following expressions (2-1) and (2-2) are obtained.

That is, in the drive force distribution function of the drive control apparatus according to the embodiment of the present invention, the input torque T _i is a reference set by the number of gear teeth in the compound planetary gear mechanism of the center differential 10 in the absence of the additional torque T _m. The torque is divided into torques Tf and Tr and transmitted to the front and rear wheels. Therefore, the reference torque distribution ratio Tf: Tr can be freely set by appropriately setting the number of gear teeth in the compound planetary gear mechanism of the center differential 10.

When the additional torque T _m is added, a torque of (1 / γ) · T _m is deprived from the reference torque Tf on the front wheel side, and (1 + 1 / γ) with respect to the reference torque Tr on the rear wheel side. ) since T _m torque so that the flows of, by varying the electric motor torque T _m to be added, it is possible to adjust the torque distribution ratio between the front and rear wheels variable.

Here, since the second motor generator 5 is coupled to the sun gear 21, the assist amount added to the reference torques Tf and Tr is (1 / γ) · T _m and (1 + 1) as described above. / Γ) · T _m . Since γ = Z _SUN / Z _RING <1, (1 / γ) · T _m > T _m , (1 + 1 / γ) · T _m > T _m , and the actual additional torque T _m is amplified. It becomes possible to assist the reference torques Tf and Tr of the front and rear wheels, the torque distribution ratio can be effectively made variable, and the second motor generator 5 can be downsized.

Figure 4 is an explanatory view showing a graph of the torque distribution characteristic due to such additional torque T _m. Here, the torque distribution ratio (front torque distribution ratio) on the front wheel side is τ _F = T _F / (T _F + T _R ), and the torque distribution ratio (rear torque distribution ratio) on the rear wheel side is τ _R = T _R / ( T _F + T _R ), each τ _F , τ _R is expressed by the following formulas (3-1) and (3-2) by the aforementioned α, β, γ and t = T _m / T _i . The

FIG. 4 is a graph of this relational expression with t as the horizontal axis and τ _F , τ _R as the vertical axis. As is apparent from FIG. 4, the additional torque T _m is expressed as a function of the input torque T _i . Τ _F and τ _R can be changed from 0 to 1, respectively, by making the addition amount variable by adding to both the positive and negative sides. That is, in the drive control device according to an embodiment of the present invention, basically, the addition in accordance with the addition amount of the torque T _m, 100 of the front wheel unbalance torque distribution ratio between the front and rear wheels: 0 to 0 of the rear wheel unbalance: It is possible to change freely up to 100. Further, such a change in the torque distribution ratio can be performed only by controlling the additional torque T _m , so that the torque distribution ratio can be actively and freely changed regardless of the differential function of the center differential 10. It becomes possible.

  Hereinafter, various controls based on such a driving force distribution function will be described.

[Direct AWD travel]
Based on the detection result of the wheel speed sensor 41A, the slip of the front wheel or the rear wheel is detected, and the differential limiting clutch 4 is controlled to be engaged when the slip is detected. According this, at the time of opening of the differential limiting clutch 4, it is possible to perform torque distribution ratio control of the front and rear wheels based on the additional torque T _m of a second motor-generator 5 and, if necessary, the differential limiting clutch Since the direct connection AWD in which the 4 is in the fastening state can be realized, the traction performance at the time of slipping described above is improved.

[EV travel control]
In order to use the driving force of the second motor generator 5 more effectively, the differential limiting clutch 4 is engaged with the drive source 1 stopped, and the additional torque T _m of the second motor generator 5 is increased. By performing the control, the EV traveling of the second motor generator 5 alone becomes possible. According to this, fuel efficiency can be improved by combining with the energy management control, and EV driving by the second motor generator 5 is possible with the driving force transmission from the driving source 1 to the center differential 10 cut off. Thus, the shock due to the engine driving force when the engine is restarted is not transmitted to the output shaft, and the engine can be restarted smoothly.

  In particular, the EV traveling of the second motor generator 5 alone is suitable for traveling from an idle stop. This control will be described with reference to FIG. After the start of control (S1-1), when a vehicle stop is detected based on the detection result of the wheel speed sensor 41A (S1-2), it is determined whether or not idle stop control is selected (S1-3). When the idle stop control is not selected, the engine 1A is kept in the idle state (S1-4). And when idle stop control is selected, after vehicle stop (S1-1) detection, engine 1A is stopped and idle stop is performed (S1-5).

  Based on the detection result of the battery sensor 41G, the currently detected SOC value is compared with the reference value (S1-6). If (SOC value−reference value) ≧ 0 is NO, the engine is started. In the standby state (S1-10), it waits for the release of the idle stop (brake release detection by the brake sensor 41C). When (SOC value−reference value) ≧ 0 is YES, the second motor generator 5 is ready for operation (S1-7), and the differential limiting clutch 4 is brought into the engaged state (S1-8). Then, the vehicle waits for the release of the idle stop in the EV running standby state.

  That is, when the vehicle is stopped by operating the brake and the engine 1A is stopped by the idle stop control and the brake is released and the vehicle is started again, the reference value defined by the SOC value of the battery 9 by the battery sensor 41G When it is larger and sufficiently charged, the EV 1 is driven by engaging only the second motor generator 5 by engaging the differential limiting clutch 4 while the engine 1A is stopped, and the detected SOC value is When the battery is not in a proper charged state lower than the prescribed reference value, the engine 1A is restarted at the same time as the brake is released, and normal running is performed.

  According to this, depending on the state of charge of the battery 9, it is determined whether to shift to EV traveling using only the second motor generator 5 or to normal traveling using the driving force of the engine 1A. The battery 9 can be prevented from being depleted at the same time as energy efficiency is improved.

[Total driving force adjustment control]
As described above, although would gross vehicle driving force by adding the torque T _m of the second motor-generator 5 is increased or decreased, the to add a power driving force in accordance with the increase of the gross vehicle driving force 1 The regenerative operation of the motor generator 1B can absorb the increase in the total vehicle driving force.

According to this, while control of the front and rear wheel torque distribution ratio according to the additional torque T _m, the total drive force during normal running can be controlled to be kept constant. That is, for example, by using the wheel speed information detected by the wheel speed sensor 41A and the accelerator opening information detected by the accelerator opening sensor 41B, the engine torque map for the wheel speed information and the accelerator opening information can be used in the traveling state. The engine torque is estimated, and at the same time, based on the detected wheel speed information, the longitudinal G information detected by the longitudinal G sensor 41D, the lateral G information detected by the lateral G sensor 41E, and the yaw rate information detected by the yaw rate sensor 41F. the target longitudinal driving force distribution ratio calculated Te calculated, the driving force distribution ratio of the vehicle to this target longitudinal driving force distribution ratio, the process of calculating additional torque T _m required constant by another determination means When it is determined that the vehicle is traveling at a normal speed (not including acceleration), the calculated additional torque _Tm is used as the first electric power. It converts into the power generation torque on the shaft which is driving the dynamic generator 1B, and the 1st motor generator 1B is regeneratively operated with the converted torque amount.

  In contrast to this control, torque assist control for increasing the total vehicle driving force can also be performed.

This control uses, for example, the wheel speed information detected by the wheel speed sensor 41A and the accelerator opening information detected by the accelerator opening sensor 41B, and is based on the engine torque map for the wheel speed information and the accelerator opening information. At the same time, the detected wheel speed information, the longitudinal G information detected by the longitudinal G sensor 41D, the lateral G information detected by the lateral G sensor 41E, and the yaw rate information detected by the yaw rate sensor 41F It obtains a target front-rear driving force distribution ratio calculated based on the drive force distribution ratio of the vehicle to this target longitudinal driving force distribution ratio, in the process of calculating the required additional torque T _m, another determination means If it is determined that the vehicle is in a state where acceleration or driving force is required, the first motor generator 1B Lower the torque, and by recalculating the additional torque T _m to the target driving force distribution ratio, to increase the total drive force of the vehicle.

These control examples will be described with reference to FIG. 6. As shown in FIG. 6A, after the start of control (S 2-1), as described above, the wheel speed information and the accelerator opening information are used to The engine torque in the running state is estimated from the engine torque map with respect to the accelerator opening information, and at the same time, the target longitudinal driving force distribution ratio is calculated based on the wheel speed information, the longitudinal G information, the lateral G information, and the yaw rate information (S2). -2). Then, the initial additional torque T _m0 is calculated by the following equation (4-1) so that the vehicle driving force distribution becomes the target longitudinal driving force distribution ratio (S2-3).

Next, the calculated initial additional torque T _m0 is converted into the power generation torque on the shaft driving the first motor generator 1B, and the additional power generation torque ΔT _g to the first motor generator 1B is expressed by the formula (4 -2) (S2-4). As shown in FIG. 6B, the additional power generation torque gain K at this time is set to 1 when the torque opening is determined based on, for example, the accelerator opening, and the accelerator opening is equal to or less than a predetermined value x. Then, it is determined whether or not the normal traveling for controlling the vehicle total driving force to be constant is performed (S2-5). When the normal traveling is performed, the additional torque _Tm is calculated by the equation (4-3). (S2-6), power to drive the first motor generator 1B in addition generation torque [Delta] T _g causes motor driven by the second motor-generator 5 additional torque T _m (S2-7). On the other hand, when the above-described normal running is not performed, the torque assist additional torque T _m1 is calculated by Equation (4-4) (S2-8), and the additional torque T _m is recalculated by Equation (4-5). (S2-9).

In such control, even when the additional torque _Tm is output in order to change the driving force distribution ratio of the front and rear wheels, the vehicle can travel while keeping the vehicle total driving force constant. Can be amplified by torque assist control.

  In addition, in a state in which the differential limiting clutch 4 is engaged, the driving force of the driving source 1 (the engine 1A and the first motor generator 1B) and the second motor generator 5 is output, thereby satisfying the maximum driving force request. Can also be done.

The control at the time of this maximum driving force request (kick down) will be described with reference to FIG. After the start of control (S3-1), when the maximum driving force is requested by sudden depression of the accelerator (S3-2), the state of charge of the battery 9 is confirmed, and the SOC value of the second battery 9B is equal to or higher than the reference value. in (S3-3), in the case of the first battery 9A battery voltage is above the reference value (S3-4) calculates the center differential input torque T _i from the engine torque estimated value of the running state (S3-5 ). Then, the possible front / rear driving force distribution ratio τ _tmax at the time of the maximum driving force output is calculated by the equation (5-1) (S3-6). Here, the maximum additional torque T _mmax is the maximum motor torque that can be output by the second motor generator. Next, the front / rear driving force distribution ratio difference Δτf is obtained by Equation (5-2) (S3-7), and Δτf is converted to the clutch engagement torque Tc of the differential limiting clutch 4 by Equation (5-3) ( S3-8). Then, the differential limiting clutch 4 is engaged by this clutch engagement torque Tc (S3-9), and after the clutch engagement, the driving force of the drive source 1 (the engine 1A and the first motor generator 1B) and the second motor generator 5 are engaged. The additional torque _Tm is output (S3-10). Further, when the SOC value of the second battery 9B is less than the reference value (S3-3) or the battery voltage of the first battery 9A is less than the reference value (S3-4), the normal driving force distribution control is executed ( S3-11).

  According to this, for example, when the driver demands the maximum driving force and the battery charge is sufficient, such as kickdown, the first motor generator 1B is driven with the differential limiting clutch 4 engaged. By performing driving force assist as a motor and performing torque assist by the second motor generator 5, it is possible to output a driving force that meets the maximum driving force requirement. The clutch engagement torque of the differential limiting clutch 4 at this time is calculated from the sum of the driving force of the engine 1A and the driving force of the first motor generator 1B and the magnitude of the additional torque of the second motor generator 5, thereby The differential limiting clutch 4 is engaged.

[Control during regeneration]
In the case where the driving force output from the driving source 1 is transmitted to the transmission 3 and the center differential 10 via the torque converter 2, in the regeneration using only the first motor generator 1B, the regenerative braking is performed when the lockup clutch 2A is released. Torque is absorbed by the torque converter 2 and high regeneration efficiency cannot be obtained.

  Therefore, during regenerative braking, control is performed to switch between regeneration by the first motor generator 1B and regeneration by the second motor generator 5 depending on whether the lockup clutch 2A is engaged or released.

  Specifically, during regeneration at the time of braking or engine braking, when the lockup clutch 2A is engaged, regeneration is performed by the first motor generator 1B, and when the lockup clutch 2A is released, the second electric motor Regeneration is selected with the generator 5.

  In addition, when regeneration at the second motor generator 5 is selected by releasing the lock-up clutch 2A, the clutch of the differential limiting clutch 4 according to the regeneration torque of the second motor generator 5 as necessary. After the engagement torque is generated and the differential limiting clutch 4 is engaged, regeneration by the second motor generator 5 is performed.

  The flow of selection control during regeneration will be described with reference to FIG. When control is started by brake operation or engine brake operation (S4-1), regenerative torque Tb on the propeller shaft is calculated (S4-2), and it is determined whether or not the lockup clutch 2A is engaged (S4-2). S4-3) When the lockup clutch 2A is engaged, the regenerative torque Tbg on the output shaft of the first motor generator 1B is calculated by Tbg = Tb / Gr (Gr is the current gear ratio) (S4-). 4). Then, the first motor generator 1B is regeneratively operated to generate regenerative torque (S4-5). On the other hand, when the lock-up clutch 2A is released, the clutch engagement torque of the differential limiting clutch 4 is calculated (S4-6), and the second motor generator 5 is regenerated after the clutch engagement (S4-7). Thus, regenerative torque is generated (S4-8).

  According to this, it is possible to improve the regeneration efficiency by regeneration by selecting the first motor generator 1B and the second motor generator 5 in accordance with the engagement and disengagement state of the lockup clutch 2A of the torque converter 2. That is, when the lock-up clutch 2A is released, the regenerative efficiency in the first motor generator 1B is reduced due to slipping of the torque converter. Therefore, by regenerating in the second motor generator 5, slipping of the torque converter 2 occurs. Energy regeneration can be performed without loss.

Also, when generating the regeneration torque by the second motor-generator 5, it becomes the braking force distribution of the rear unbalance for driving force distribution changing function (the change before and after the torque distribution ratio by negative additional torque T _m) Therefore, if necessary, the differential limiting clutch 4 is engaged to cancel the driving force distribution changing function, and the second motor generator 5 can output the target regenerative torque without being affected by this.

[Driving mode change control]
The travel mode switch 42 of the manual or automatic switch is provided, depending on the selected driving mode, to change the target longitudinal driving force distribution ratio, and outputs the additional torque T _m calculated accordingly.

  According to this, for example, when driving in the city, select a driving mode with emphasis on fuel efficiency to achieve a target driving force distribution ratio aiming at improving fuel efficiency, and select driving mode with emphasis on mobility while driving on mountain roads with many corners. By setting the target driving force distribution ratio to improve performance, vehicle characteristics that meet the driver's requirements can be provided.

  Each control explained above can be used alone or in combination.

Explanatory drawing of a prior art. The system block diagram of the drive control apparatus of the all-wheel drive vehicle which concerns on embodiment of this invention. Explanatory drawing explaining the basic driving force distribution function in embodiment of this invention. Explanatory drawing explaining the basic driving force distribution function in embodiment of this invention. It is control flow explanatory drawing explaining the control (EV driving control) which the drive control apparatus of the all-wheel drive vehicle which concerns on embodiment of this invention performs. It is control flow explanatory drawing explaining the control (total driving force adjustment control) which the drive control apparatus of the all-wheel drive vehicle which concerns on embodiment of this invention performs. It is control flow explanatory drawing explaining the control (control at the time of the largest driving force request | requirement) which the drive control apparatus of the all-wheel drive vehicle which concerns on embodiment of this invention performs. It is control flow explanatory drawing explaining the control (control at the time of regeneration) which the drive control apparatus of the all-wheel drive vehicle which concerns on embodiment of this invention performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive source 1A Engine 1B 1st motor generator 2 Torque converter 2A Lock-up clutch 3 Transmission 4 Differential limiting clutch 5 2nd motor generator 6 1st inverter 7 2nd inverter 8 DC / DC converter 9 Battery 9A 1st Battery (12V)
9B Second battery 10 Center differential 20 Motor torque adding mechanism 20A Driving force distribution changing mechanism 40 Electronic control unit (control means)
41 detector (wheel speed sensor 41A, accelerator opening sensor 41B, brake sensor 41C, front and rear G sensor 41D, lateral G sensor 41E, yaw rate sensor 41F, battery sensor 41G)
42 Travel mode switch

Claims (7)

A drive control device for an all-wheel drive vehicle that controls the drive force distributed to the front and rear wheels,
A drive source having a first motor generator coupled to the engine output shaft;
One input element to which the driving force from the driving source is input and two output elements for transmitting the driving force to the front and rear wheels of the vehicle, respectively, and one of the input element and the output element is arranged coaxially. A center differential that outputs the input driving force to each output element at a set reference torque distribution ratio;
A differential limiting clutch that engages and synchronizes rotation between the output elements;
A driving force distribution change mechanism that changes a distribution ratio of the driving force transmitted from the output elements to the front and rear wheels by adding a driving force between the output elements;
A second motor generator coupled to the driving force distribution changing mechanism;
Control means for controlling operation of the drive source and the second motor generator and engagement / non-engagement of the differential limiting clutch;
The control means controls the additional driving force of the second motor generator by engaging the differential limiting clutch with the drive source stopped. apparatus. The center differential is
A first sun gear; a second sun gear arranged coaxially with the first sun gear; a first pinion meshing with the first sun gear around the first and second sun gears; and the first pinion integrally A second pinion that is formed and meshes with the second sun gear, wherein the first sun gear is the input element, and the second sun gear is a first output element that transmits driving force to one of the front and rear wheels of the vehicle. The support member that supports the first and second pinions is a second output element that transmits a driving force to the other of the front and rear wheels of the vehicle,
The driving force distribution changing mechanism is
A first transmission element coupled to the first output element; a second transmission element coupled to the second output element; and a sun gear disposed coaxially with the first and second sun gears. 2. The drive control apparatus for an all-wheel drive vehicle according to claim 1, further comprising a planetary gear mechanism, wherein the second motor generator is connected to the sun gear.   The control means detects that the brake is released from a state in which the vehicle brake is operated and the drive source is stopped, and the state of charge of the battery that supplies power to the second motor generator is good. In such a case, electric running is performed by the additional driving force of the second motor generator, and normal running is performed by restarting the driving source when the state of charge of the battery is poor. Item 3. The drive control device for an all-wheel drive vehicle according to Item 1 or 2. The control means obtains an estimated output driving force and a target front / rear driving force distribution ratio of the drive source in the current traveling state, and is necessary for making the front / rear wheel driving force distribution ratio of the vehicle the target front / rear driving force distribution ratio. In the process of obtaining the additional driving force of the second motor generator,
4. The regenerative operation of the first motor generator according to claim 1, wherein the first motor generator is regenerated so as to add a power generation driving force corresponding to an increase in the total driving force due to the additional driving force of the second motor generator. The drive control apparatus of the all-wheel drive vehicle described in any one. The control means obtains an estimated output driving force and a target front / rear driving force distribution ratio of the drive source in the current traveling state, and is necessary for making the front / rear wheel driving force distribution ratio of the vehicle the target front / rear driving force distribution ratio. In the process of obtaining the additional driving force of the second motor generator,
The additional driving force of the second motor generator required to reduce the power generation driving force by the first motor generator and to achieve the target front-rear driving force distribution ratio is obtained again. 4. A drive control device for an all-wheel drive vehicle according to any one of 4).   The control means changes the target front / rear driving force distribution ratio according to the selected travel mode, and the vehicle front / rear wheel driving force distribution ratio is changed to the changed target front / rear driving force distribution ratio. 6. The drive control apparatus for an all-wheel drive vehicle according to claim 4, wherein an additional driving force of the second motor generator is obtained. In the drive power from the drive source is output via a torque converter with a lock-up clutch,
2. The control unit according to claim 1, wherein, when the lockup clutch is opened during regenerative braking, the differential limiting clutch is engaged and the second motor generator is regeneratively operated. The drive control apparatus of the all-wheel drive vehicle described in any one of -6.

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