Electric motor type four-wheel drive vehicle driving device

Abstract

The present invention relates to a driving device for an electric motor type four-wheel drive vehicle, and provides a driving device for an electric motor type four-wheel drive vehicle that can use a transmission shaft to achieve effective driving force transmission of an electric motor. The driving device for an electric motor type four-wheel drive vehicle on one aspect of the present invention comprises: a transmission shaft that transmits power between the front wheel side and the rear wheel side; a first differential mechanism that is arranged on the driving shaft on the front wheel side; a second differential mechanism that is arranged on the driving shaft on the rear wheel side; a first separation mechanism that separates the connection between the first differential mechanism and the transmission shaft; a second separation mechanism that separates the connection between the second differential mechanism and the transmission shaft; a first motor that is connected to one side of the transmission shaft that is closer to the front wheel side than the first separation mechanism and closer to the rear wheel side than the second separation mechanism; and a second motor that is connected between the first separation mechanism and the second separation mechanism.

Description

Technical Field

[0001] The present invention relates to a driving system technology of an electric vehicle driven by an electric motor, and more particularly to a driving device of an electric motor type four-wheel drive vehicle in which front wheels and rear wheels are driven by a plurality of electric motors. Background Art

[0002] In recent years, electric vehicles driven by electric motors have attracted attention again from the perspective of depletion of fossil fuels such as petroleum or energy saving. Among such electric vehicles, two-wheel drive systems with the front wheels or rear wheels as driving wheels, or four-wheel drive systems with all four wheels as driving wheels are known.

[0003] Among them, four-wheel drive systems of electric vehicles are roughly divided into a type in which electric motors are provided on wheels and a type in which power is transmitted from the electric motors to the drive wheels via a power transmission mechanism.

[0004] As an in-wheel motor type in which an electric motor is mounted on each of the four wheels, for example, Patent Document 1 can be cited. Also, as a dual-motor type in which two electric motors drive the front and rear wheels respectively, for example, Patent Document 2 can be cited. Furthermore, as a hybrid type in which one electric motor drives one of the front and rear wheels while the other wheel is provided with an in-wheel motor, for example, Patent Document 3 can be cited.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-92995

[0008] Patent Document 2: Japanese Patent Application Publication No. 2018-70076

[0009] Patent Document 3: Japanese Patent Application Publication No. 2014-87251 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, not limited to the above-mentioned patent documents, it cannot be said that the current technology has appropriately met the needs of the market, and the above-mentioned methods have the following problems.

[0012] First, all the drive systems exemplified in the above patent documents do not have a transmission shaft as a mechanical component. Although not having a transmission shaft is good from the perspective of weight reduction, it is difficult to achieve performance like the existing established internal combustion engine four-wheel drive vehicle.

[0013] That is, for example, when one of the left and right drive wheels slips on an uneven road, the drive force generated by the electric motor cannot be redistributed to the non-slipping drive wheel due to the structure. Furthermore, if only the non-slipping drive wheel is used to cope with such a slipping state, the torque capacity of the electric motor mounted on the vehicle must be increased, which leads to a significant increase in cost and volume, and is therefore unrealistic.

[0014] Thus, it is very difficult to ensure the same performance as that of an internal combustion engine four-wheel drive vehicle in the prior art, and there is still much room for improvement in the efficient transmission of driving force by the electric motor.

[0015] The present invention has been made in view of the above-mentioned problems as one example, and an object of the present invention is to provide a driving device for an electric motor type four-wheel drive vehicle that can realize efficient transmission of driving force of an electric motor using a propeller shaft.

[0016] Technical solutions to solve problems

[0017] In order to solve the above-mentioned problems, one embodiment of the present invention provides a driving device for an electric motor type four-wheel drive vehicle, (1) the driving device for an electric motor type four-wheel drive vehicle comprises: a transmission shaft, which transmits power between the front wheel side and the rear wheel side; a first differential mechanism, which is arranged on the driving shaft on the front wheel side; a second differential mechanism, which is arranged on the driving shaft on the rear wheel side; a first separation mechanism, which separates the connection between the first differential mechanism and the transmission shaft; a second separation mechanism, which separates the connection between the second differential mechanism and the transmission shaft; a first motor, which is connected to one side of the transmission shaft that is closer to the front wheel side than the first separation mechanism and to the rear wheel side than the second separation mechanism; and a second motor, which is connected between the first separation mechanism and the second separation mechanism.

[0018] Furthermore, in the electric motor type four-wheel drive vehicle driving device described in (1) above, (2) it is preferable that the output shaft of the first motor is arranged in parallel with the driving shaft on the front wheel side.

[0019] In the electric motor type four-wheel drive vehicle driving device described in (1) or (2) above, (3) it is preferred that the output shaft of the second motor is arranged in parallel with the propeller shaft.

[0020] In addition, in the electric motor four-wheel drive vehicle drive device described in any one of (1) to (3) above, (4) preferably, the maximum output of the second motor is higher than the maximum output of the first motor, and the second motor is connected to the drive shaft via a transmission or a reducer.

[0021] In addition, in the driving device of the electric motor type four-wheel drive vehicle described in any one of the above (1) to (4), (5) it is preferred that it also includes a control device, which controls the separation of the first separation mechanism and the second separation mechanism, and the control device controls the separation of the first separation mechanism and the second separation mechanism according to the output status of the first motor and the second motor.

[0022] In addition, in the drive device of the electric motor type four-wheel drive vehicle described in (5) above, (6) it is preferred that the control device controls the first separation mechanism and the second separation mechanism to maintain the connection between the first differential mechanism and the transmission shaft, and maintain the connection between the second differential mechanism and the transmission shaft, and does not output from the first motor, but transmits the output from the second motor to the drive shaft on the front wheel side and the drive shaft on the rear wheel side via the transmission shaft.

[0023] In addition, in the drive device of the electric motor type four-wheel drive vehicle described in (5) or (6) above, (7) it is preferred that the control device controls the first separation mechanism and the second separation mechanism to separate the connection between the first differential mechanism and the transmission shaft, and separate the connection between the second differential mechanism and the transmission shaft, and does not perform the output from the second motor, but transmits the output from the first motor to the drive shaft on the front wheel side.

[0024] In addition, in the drive device of the electric motor type four-wheel drive vehicle described in any one of the above (5) to (7), (8) it is preferred that the control device controls the first separation mechanism and the second separation mechanism to maintain the connection between the first differential mechanism and the transmission shaft, and maintain the connection between the second differential mechanism and the transmission shaft, and the output from the first motor and the output from the second motor are transmitted to the drive shaft on the front wheel side and the drive shaft on the rear wheel side via the transmission shaft.

[0025] In addition, in the drive device of the electric motor type four-wheel drive vehicle described in any one of the above (5) to (8), (9) it is preferred that the control device controls the first separation mechanism and the second separation mechanism to separate the connection between the first differential mechanism and the transmission shaft and maintain the connection between the second differential mechanism and the transmission shaft, transmits the output from the first motor to the drive shaft on the front wheel side, and transmits the output from the second motor to the drive shaft on the rear wheel side.

[0026] Effects of the Invention

[0027] According to the present invention, it is possible to realize efficient transmission of driving force while maintaining high passability and steering stability on various road conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a block diagram showing a driving force transmission system in an electric motor type four-wheel drive vehicle according to an embodiment.

[0029] Figure 2 It is a state comparison diagram showing the control states of each electric motor and the release mechanism by the control unit.

[0030] Figure 3 1 is a schematic diagram schematically showing a state in which the driving force of the electric motor is transmitted to the driving wheels in the first state.

[0031] Figure 4 1 is a schematic diagram schematically showing a state in which the driving force of the electric motor is transmitted to the driving wheels in the second state.

[0032] Figure 5 1 is a schematic diagram schematically showing a state in which the driving force of the electric motor is transmitted to the driving wheels in the third state.

[0033] Figure 6 1 is a schematic diagram schematically showing a state in which the driving force of the electric motor is transmitted to the driving wheels in the fourth state.

[0034] Figure 7 1 is a flowchart showing a drive control method in the electric motor type four-wheel drive vehicle according to the embodiment.

[0035] Explanation of symbols

[0036] 100 Electric motor 4x4

[0037] 10 Drive shaft

[0038] 20 First differential mechanism

[0039] 30 Second differential mechanism

[0040] 40 First separation mechanism

[0041] 50 Second separation mechanism

[0042] MG1 First Motor

[0043] MG2 Second Motor

[0044] ECU control unit DETAILED DESCRIPTION

[0045] Next, a preferred embodiment for implementing the present invention is described. In addition, in the following description, for the convenience of description, the vehicle height direction of the electric motor four-wheel drive vehicle 100 is defined as the Z direction, the vehicle length direction is defined as the Y direction, and the vehicle width direction orthogonal to these Z direction and Y direction is defined as the X direction for description. However, it goes without saying that the present invention does not depend on the provisions of the above directions and does not inappropriately narrow the scope of the claims. In addition, for structures other than those described in detail below, the known technologies including the above patent documents can also be appropriately supplemented.

[0046] <Electric Motor Type Four-wheel Drive Vehicle 100>

[0047] First, refer to Figure 1 The structure of an electric motor type four-wheel drive vehicle 100 according to a preferred embodiment of the present invention will be described.

[0048] As shown in the figure, the electric motor four-wheel drive vehicle 100 of this embodiment is an electric vehicle that uses an electric motor to drive a drive wheel 1, and includes a transmission shaft 10, a first differential mechanism 20, a second differential mechanism 30, a first separation mechanism 40, a second separation mechanism 50, a first motor MG1, a second motor MG2 and a control unit ECU.

[0049] The driving wheels 1 in this embodiment include a right front wheel 1RF and a left front wheel 1LF constituting the front wheel side, and a right rear wheel 1RR and a left rear wheel 1LR constituting the rear wheel side. Figure 1 As shown, the right front wheel 1RF and the left front wheel 1LF are connected via a front wheel drive shaft 11F and a first differential mechanism 20 as a differential mechanism. In addition, the right rear wheel 1RR and the left rear wheel 1LR are connected via a rear wheel drive shaft 11R and a second differential mechanism 30 as a differential mechanism.

[0050] The transmission shaft 10 has a function of transmitting driving force (rotation) between the front wheel side and the rear wheel side. More specifically, a driving pinion gear as a fifth gear g5 is provided at the end of the front wheel side of the transmission shaft 10. The fifth gear g5 can mesh with the fourth gear g4 linked to the first separation mechanism 40 described later. On the other hand, a driving pinion gear as a sixth gear g6 is provided at the end of the rear wheel side of the transmission shaft 10. The sixth gear g6 can mesh with the rear driving pinion gear 32 linked to the second separation mechanism 50 described later.

[0051] In the present embodiment, the first differential mechanism 20 is provided on the drive shaft 11F on the front wheel side. The first differential mechanism 20 functions as the above-mentioned differential mechanism, thereby being able to provide a difference in rotation speed between the right front wheel 1RF and the left front wheel 1LF when turning, etc. More specifically, the first differential mechanism 20 includes a ring gear 22 meshing with the third gear g3 described later and a differential case 21 rotatably engaged with the ring gear 22. In the differential case 21, similar to other known differential device structures, a side gear (not shown) connected to the drive shaft 11F of the right front wheel 1RF and the left front wheel 1LF is arranged on the left and right, and two pinions (not shown) are arranged in a form meshing with the gears of both parties.

[0052] In the present embodiment, the second differential mechanism 30 is provided on the drive shaft 11R on the rear wheel side. The second differential mechanism 30, like the first differential mechanism 20, can provide a difference in rotation speed between the right rear wheel 1RR and the left rear wheel 1LR when turning. More specifically, the second differential mechanism 30 includes an orthogonal gear 32 meshing with the sixth gear g6 described above and a differential case 31 rotatably engaged with the orthogonal gear 32. In the differential case 31, in addition to the side gears and pinions not shown above, a second separation mechanism 50 described later is also provided.

[0053] The first separation mechanism 40 is configured to have a function of separating the connection between the first differential mechanism 20 and the transmission shaft 10. More specifically, the first separation mechanism 40 of the present embodiment, under the control of the control unit ECU described later, can achieve two states: a state in which the first differential mechanism 20 is connected to the transmission shaft 10 and can transmit the driving force, and a state in which these connections are cut off and the driving force cannot be transmitted. As a specific structure of such a first separation mechanism 40, for example, a well-known clutch mechanism such as a dog clutch and a disconnection mechanism exemplified in Japanese Patent Application Laid-Open No. 2018-17354 can be adopted.

[0054] The second separation mechanism 50 is configured to have a function of separating the connection between the second differential mechanism 30 and the transmission shaft 10. More specifically, the second separation mechanism 50 of the present embodiment can realize two states, a state in which the second differential mechanism 20 is connected to the transmission shaft 10 and the driving force can be transmitted, and a state in which the connection is cut off and the driving force cannot be transmitted, under the control of the control unit ECU described later. As a specific structure of such a second separation mechanism 50, the same structure as the first separation mechanism 40 can also be adopted.

[0055] The first motor MG1 is connected to one of the following sides: the front wheel side of the first release mechanism 40 and the rear wheel side of the second release mechanism 50 relative to the above-mentioned propeller shaft 10. That is, the first motor MG1 can be arranged on the front wheel side or the rear wheel side. Figure 1 As shown, the first motor MG1 is connected to the front wheel side of the first disconnect mechanism 40. Thus, the driving force from the first motor MG1 is transmitted to the fifth gear g5 of the propeller shaft 10 via the front wheel side drive shaft 11F and the first disconnect mechanism 40.

[0056] As a specific example of such a first motor MG1, a well-known synchronous motor or the like controlled via an inverter or the like (not shown) may be applied.

[0057] In addition, in this embodiment, if Figure 1 As can be seen, the output shaft OS1 of the first motor MG1 can also be arranged in parallel with the drive shaft 11F on the front wheel side (this arrangement of the motor is also called "transverse arrangement"). As a result, the driving force generated by the first motor MG1 can be efficiently transmitted (to the drive shaft 11F on the front wheel side in this example) by using spur gears instead of orthogonal gears.

[0058] In addition, since there is no orthogonal gear involved when regenerative charging is performed on the battery (not shown), the transmission efficiency from the drive wheel to the first motor MG1 can be suppressed from decreasing. Thus, in the present embodiment, since regenerative charging is performed using the first motor MG1 mechanically connected to the front wheel side instead of the second motor MG2 mechanically connected to the propeller shaft 10, regenerative charging of the battery can be performed with higher efficiency.

[0059] The second motor MG2 is connected between the first release mechanism 40 and the second release mechanism 50. More specifically, in the present embodiment, the first release mechanism 40 and the second release mechanism 50 are connected to the transmission shaft 10 via a known speed reducer 60. In addition, the second motor MG2 of the present embodiment is connected to the transmission shaft 10 via the above-mentioned speed reducer 60, but is not limited to this mode, and may be connected via a known transmission instead of the speed reducer 60.

[0060] In addition, in the present embodiment, the output shaft OS2 of the second motor MG2 may also be Figure 1 The arrangement shown is parallel to the transmission shaft 10. In other words, in this embodiment, it is preferred that the output shaft OS1 of the first motor MG1 and the output shaft OS2 of the second motor MG2 are arranged orthogonally to each other. Thus, the second motor MG2 can also transmit driving force to the transmission shaft 10 without intervening orthogonal gears.

[0061] The maximum output (rated output) of the second motor MG2 is preferably higher than the maximum output (rated output) of the first motor MG1. This allows more appropriate torque distribution to be achieved in accordance with the running state in torque distribution control by the control unit ECU described later.

[0062] <Detailed Structure of Driving Force Transmission System>

[0063] like Figure 1 As shown, in this embodiment, a first gear g1 composed of a spur gear is provided on the output shaft OS1 of the first motor MG1. In addition, an intermediate shaft Ts capable of relaying the driving force from the first motor MG1 and the regenerative force from the driving wheel is provided between the output shaft OS1 of the first motor MG1 and the driving shaft 11F on the front wheel side.

[0064] In the present embodiment, the intermediate shaft Ts is arranged parallel to the output shaft OS1 of the first motor MG1 and the drive shaft 11F on the front wheel side. In addition, the second gear g2 meshing with the first gear g1, the third gear g3 meshing with the ring gear 22, the fourth gear g4 composed of orthogonal gears, and the first release mechanism 40 are respectively engaged with the intermediate shaft Ts.

[0065] Therefore, for example, the driving force generated by the first motor MG1 is sequentially transmitted to the first gear g1, the second gear g2, the third gear g3, and the ring gear 22 to reach the driving wheel of the drive shaft 11F on the front wheel side. In addition, when the first release mechanism 40 is in the maintained state, the driving force generated by the first motor MG1 is sequentially transmitted to the first gear g1, the second gear g2, and the fourth gear g4 to reach the fifth gear g5 of the propeller shaft 10. In other words, at least a part of the rotation of the first motor MG1 can be transmitted to the propeller shaft 10 or the drive shaft 11R on the rear wheel side via the first release mechanism 40.

[0066] <Torque distribution control by control unit ECU>

[0067] Next, use Figure 2 The torque distribution control performed by the control unit ECU in this embodiment will be described in detail.

[0068] The control unit ECU of this embodiment is constructed with a well-known microcomputer as the center, controls the first motor MG1 and the second motor MG2 via an inverter (not shown), and includes a well-known vehicle dynamics control (VDC) unit for controlling vehicle behavior, etc. Various control units exchange control information such as various calculation values ​​or control parameter information detected by various sensors such as a vehicle speed sensor, via an in-vehicle network (CAN, etc.) formed by a communication bus, and execute motor driving force control and vehicle behavior control, etc.

[0069] The control unit ECU has a function of performing optimal torque distribution to the front and rear drive wheels by controlling the above-mentioned driving force transmission system. More specifically, the control unit ECU in this embodiment has a function of controlling the disengagement of the above-mentioned first disengagement mechanism 40 and the second disengagement mechanism 50 .

[0070] Figure 2An example of the front-rear torque distribution control performed by such a control unit ECU is shown in FIG.

[0071] As shown in the figure, the control unit ECU is configured to control the disengagement of the first disengagement mechanism 40 and the second disengagement mechanism 50 according to the output states of the first motor MG1 and the second motor MG2.

[0072] Below, use Figure 3 to Figure 6 An example of unlimited torque distribution control under a specific operating condition or driving state is described.

[0073] [First state]

[0074] As Figure 2 The first state shown can be exemplified when the electric motor type four-wheel drive vehicle 100 is starting or traveling on a low μ road. Figure 3 The state of transmission of driving force from the electric motor and torque distribution in the first state is shown.

[0075] As shown in these figures, the control device ECU controls the first disconnecting mechanism 40 and the second disconnecting mechanism 50 to maintain the connection between the first differential mechanism 20 and the propeller shaft 10, and to maintain the connection between the second differential mechanism 30 and the propeller shaft 10. At the same time, the control device ECU controls to stop driving the first motor MG1 and transmit driving force from the second motor MG2 to the propeller shaft 10 via the inverter (not shown).

[0076] Thus, the output from the second motor MG2 is transmitted to the front wheel drive shaft 11F and the rear wheel drive shaft 11R via the propeller shaft 10 without the output from the first motor MG1.

[0077] Here, in the present embodiment, as the first state, it is assumed that the vehicle is starting when a corresponding torque is required, or the road surface is slippery due to snow, ice, rain, etc. In such a state, the second motor MG2 with a higher output than the first motor MG1 is used and the above-mentioned maintenance state is set, thereby enabling the driving force to be stably transmitted from the second motor MG2 with a higher output to all the driving wheels via the propeller shaft 10.

[0078] [Second state]

[0079] As Figure 2 The second state shown can be exemplified by the case where the electric motor type four-wheel drive vehicle 100 is running at a substantially constant speed, or when the running state is not bad and a high torque is not required for normal running. Figure 4 The state of transmission of driving force from the electric motor and torque distribution in the second state is shown.

[0080] As shown in these figures, the control unit ECU controls the first disconnection mechanism 40 and the second disconnection mechanism 50 to disconnect the first differential mechanism 20 and the propeller shaft 10, and disconnect the second differential mechanism 30 and the propeller shaft 10. At the same time, the control unit ECU controls to stop driving the second motor MG2 and transmit the driving force from the first motor MG1 to the intermediate shaft Ts via the inverter (not shown).

[0081] As a result, the output from the second motor MG2 is not provided, and the output from the first motor MG1 is transmitted to the drive shaft 11F on the front wheel side.

[0082] As described above, since high torque is not required in the second state, a two-wheel drive structure is formed in which the driving force (torque) is distributed only to the front wheel side from the first motor MG1 with a lower output than the second motor MG2, and energy saving is emphasized. In addition, in the present embodiment, a structure is set to distribute torque only to the front wheel side from the first motor MG1, but it is not limited to this. For example, as a structure in which the first motor MG1 is provided on the rear wheel side, a structure in which the driving force (torque) is distributed only to the rear wheel side may also be set.

[0083] The second disconnecting mechanism 50 is controlled to disconnect the second differential mechanism 30 and the propeller shaft 10, but the connection between the second differential mechanism 30 and the propeller shaft 10 may be maintained as long as the connection between the first differential mechanism 20 and the propeller shaft 10 is disconnected and the output from the second motor MG2 is stopped.

[0084] [Third state]

[0085] As Figure 2 The third state shown can be used as an example when driving on an uneven road with poor road conditions or when climbing a slope that requires high torque. Figure 5 The states of transmission of driving force from the electric motor and torque distribution in the third state are shown.

[0086] As shown in these figures, the control unit ECU controls the first release mechanism 40 and the second release mechanism 50 to maintain the connection between the first differential mechanism 20 and the propeller shaft 10, and to maintain the connection between the second differential mechanism 30 and the propeller shaft 10. At the same time, the control unit ECU controls the transmission of driving force from both the first motor MG1 and the second motor MG2 to the intermediate shaft Ts and the propeller shaft 10, respectively, via the inverter (not shown).

[0087] Thus, the output from the first motor MG1 and the output from the second motor MG2 are transmitted to the drive shaft 11F on the front wheel side and the drive shaft 11R on the rear wheel side via the propeller shaft 10 and the intermediate shaft Ts.

[0088] As described above, since high torque is required in the third state, the first motor MG1 and the second motor MG2 are fully driven to distribute the maximum driving force to all front and rear drive wheels, thereby emphasizing high power. Thus, for example, a vehicle of the SUV type can achieve particularly suitable high passability through two electric motors and the propeller shaft 10.

[0089] [Fourth State]

[0090] As Figure 2 The fourth state shown can be exemplified by manually operating a small movement when driving. Figure 6 The state of transmission of driving force from the electric motor and torque distribution in the fourth state is shown.

[0091] As shown in these figures, the control unit ECU controls the first disconnection mechanism 40 and the second disconnection mechanism 50 to disconnect the first differential mechanism 20 and the propeller shaft 10, and maintain the connection between the second differential mechanism 30 and the propeller shaft 10. At the same time, the control unit ECU controls the transmission of driving force from both the first motor MG1 and the second motor MG2 to the intermediate shaft Ts and the propeller shaft 10 respectively via the inverter not shown.

[0092] Thus, the output from the first motor MG1 is transmitted to the drive shaft 11F on the front wheel side, and the output from the second motor MG2 is transmitted to the drive shaft 11R on the rear wheel side.

[0093] As described above, in the fourth state, since the vehicle has high mobility and torque is also required, such as when traveling on a loop, the first motor MG1 and the second motor MG2 are configured to distribute the driving force independently of each other in a manner that the front wheel side and the rear wheel side are shared by each other. Thus, torque vectoring can be achieved on the front wheel side and the rear wheel side, and the vehicle can travel while controlling the front and rear torque distribution via the two electric motors and the propeller shaft 10.

[0094] <Drive Control Method in Electric Motor Four-wheel Drive Vehicle 100>

[0095] Next, refer to Figure 7 , the drive control method of the electric motor type four-wheel drive vehicle 100 of the control unit ECU of this embodiment is described. In addition, in the following description, as an example of torque distribution control performed by the control unit ECU, an example of appropriately selecting the above-mentioned first state to fourth state is described. However, the first state to fourth state are exemplary, and other states may also be used.

[0096] After the driver of the electric motor type four-wheel drive vehicle 100 starts the electric motor, the control unit ECU first determines whether the automatic mode is set in step 1. Then, if the automatic mode is set in step 1, the process proceeds to step 2-1, and if the automatic mode is not set, the process proceeds to step 2-2.

[0097] In step 2-1 in which the automatic mode is set, under the control of the control unit ECU, information from various sensors such as information related to speed, acceleration, and angular velocity from the speed / acceleration sensor and gyro sensor of the electric motor four-wheel drive vehicle 100, information related to the driver's operation such as the opening of the accelerator pedal and the steering angle of the steering wheel, or various information from vehicle-mounted devices such as a vehicle-mounted camera or a navigation system are obtained. In addition, as an example of the information obtained in this step 2-2, for example, speed, acceleration, angular acceleration, vehicle speed pulse, image information, position information, or map information can be exemplified.

[0098] Next, in step 3-1, under the control of the control unit ECU, the optimal state is determined based on the various information obtained above. More specifically, the control unit ECU, for example, controls each electric motor and each separation mechanism to form the above-mentioned first state when it is determined based on the acquired vehicle speed information that the electric motor type four-wheel drive vehicle 100 is starting. In addition, for example, when it is determined based on the acceleration information and the above-mentioned map information that the electric motor type four-wheel drive vehicle 100 is climbing a slope, each electric motor and each separation mechanism are controlled to form the above-mentioned third state.

[0099] Thus, in this embodiment, the driving condition of the electric motor type four-wheel drive vehicle 100 is determined by information from various sensors and vehicle-mounted equipment, and each electric motor and each separation mechanism are controlled based on the determination result to form an optimal torque distribution. As a result, the driver can omit particularly cumbersome operations and simultaneously obtain high passability and handling stability for various road conditions. In addition, because the driving condition of the electric motor type four-wheel drive vehicle 100 is determined by information from various sensors and vehicle-mounted equipment to perform the optimal torque distribution, the two electric motors are used to achieve effective transmission of driving force to the drive wheels.

[0100] In the next step 4-1, the driver or other passengers determine whether there is a mode change. More specifically, under the control of the control unit ECU, it is determined whether there is a switch from the automatic mode to the manual mode. If there is a switch to the manual mode, the process moves to step 2-2. On the other hand, if there is no mode change, it is determined in the next step 5-1 whether the power of the electric motor is turned off. And, if the power of the electric motor is not turned off in step 5-1, the control returns to step 2-1 and continues the subsequent processing again.

[0101] Next, an example of starting in manual mode is described.

[0102] That is, if it is determined in step 1 that the mode is the manual mode, control is started in the current state in step 2-2. Usually, since the start of the electric motor is when the power supply of the electric motor is turned on, each electric motor and each separation mechanism are controlled so as to be in the first state when transferring from step 1. On the other hand, when transferring from step 4-1, the current state is maintained and control is continued.

[0103] Then, in the next step 3 - 2 , it is determined whether or not there is a change in mode. If there is a change, the control is transferred to the above-mentioned step 2 - 1 , and if there is no change, the control is transferred to step 4 - 2 .

[0104] If there is no mode change, in the next step 4-2, it is determined whether there is a state change by the driver or other passengers. If there is a state change, each electric motor or each separation mechanism is controlled to achieve the state reselected in step 5-2. On the other hand, if there is no state change in step 4-2, the control returns to step 2-2 and the subsequent control is continued.

[0105] After starting control in the state newly selected in step 5-2, it is determined whether the electric motor is stopped (powered off) in step 6. If the power of the electric motor is not turned off in step 6, control is returned to step 2-2 to continue the subsequent processing.

[0106] In this way, according to the drive device in the electric motor four-wheel drive vehicle 100 of this embodiment, a structure is adopted in which the four wheels are mechanically directly connected through two electric motors and a transmission shaft, and the torque / driving force is distributed to the drive wheels through the above-mentioned two separation mechanisms. Therefore, the rotation of these electric motors can be efficiently transmitted to the drive wheels.

[0107] In addition, according to the drive control method in the electric motor four-wheel drive vehicle 100 of this embodiment, when the automatic mode is selected, the optimal state is set based on various information obtained from vehicle-mounted sensors or equipment. Therefore, while maintaining high passability and handling stability on various road conditions, efficient transmission of driving force to the drive wheels can be achieved.

[0108] The above-described embodiment is a preferred example of the present invention, and each element of the embodiment may be appropriately combined to realize a new structure and control without departing from the spirit of the present invention.

[0109] For example, in the above embodiment, a mode in which no speed reducer or transmission is interposed in the first motor MG1 is described, but the present invention is not limited thereto and the first motor MG1 may have the same specifications as the second motor MG2, or a speed reducer or transmission may be provided on the first motor MG1 side.

[0110] In view of the efficiency of regenerative charging, an example in which regenerative charging is performed by the first motor MG1 has been described, but the present invention is not limited thereto, and regenerative charging may be performed by the second motor MG2, or by both motors.

[0111] Furthermore, in the above-described embodiment, a dual motor structure of the first motor MG1 and the second motor MG2 is used, but the present invention is not limited thereto, and a structure in which three or more electric motors are mounted in total may be used.

[0112] As described above, the driving device and control method thereof in the electric motor type four-wheel-drive vehicle of the present invention are suitable for realizing a four-wheel-drive vehicle capable of maintaining high passability and steering stability through efficient torque distribution.

Claims

1. A driving device for an electric motor type four-wheel drive vehicle, comprising: a propeller shaft that transmits power between the front wheel side and the rear wheel side; A first differential mechanism, which is provided on the drive shaft on the front wheel side; A second differential mechanism, which is provided on the drive shaft on the rear wheel side; a first disconnecting mechanism, which disconnects the first differential mechanism from the transmission shaft; a second disconnecting mechanism, which disconnects the second differential mechanism from the transmission shaft; a first motor connected to one side of the transmission shaft closer to the front wheel than the first release mechanism and closer to the rear wheel than the second release mechanism; as well as The second motor is connected between the first separation mechanism and the second separation mechanism.

2. The driving device for an electric motor type four-wheel drive vehicle according to claim 1, wherein: The output shaft of the first motor is arranged in parallel with the drive shaft on the front wheel side.

3. The driving device for an electric motor type four-wheel drive vehicle according to claim 1, wherein: An output shaft of the second motor is arranged to be parallel to the transmission shaft.

4. The driving device for an electric motor type four-wheel drive vehicle according to claim 2, wherein: An output shaft of the second motor is arranged to be parallel to the transmission shaft.

5. The driving device for an electric motor type four-wheel drive vehicle according to any one of claims 1 to 4, wherein: the maximum output of the second motor is higher than the maximum output of the first motor, The second motor is connected to the transmission shaft via a transmission or a speed reducer.

6. The driving device for an electric motor type four-wheel drive vehicle according to any one of claims 1 to 4, wherein: The device further comprises a control device, which controls the separation of the first separation mechanism and the second separation mechanism, The control device controls separation in the first separation mechanism and the second separation mechanism according to output states of the first motor and the second motor.

7. The driving device for an electric motor type four-wheel drive vehicle according to claim 6, wherein: The control device controls the first separation mechanism and the second separation mechanism to maintain the connection between the first differential mechanism and the transmission shaft, and to maintain the connection between the second differential mechanism and the transmission shaft, The output from the first motor is not transmitted, but the output from the second motor is transmitted to the drive shaft on the front wheel side and the drive shaft on the rear wheel side via the propeller shaft.

8. The driving device for an electric motor type four-wheel drive vehicle according to claim 6, wherein: The control device controls the first separation mechanism and the second separation mechanism to separate the connection between the first differential mechanism and the transmission shaft, and separate the connection between the second differential mechanism and the transmission shaft. The output from the second motor is not transmitted, and the output from the first motor is transmitted to the drive shaft on the front wheel side.

9. The driving device for an electric motor type four-wheel drive vehicle according to claim 6, wherein: The control device controls the first separation mechanism and the second separation mechanism to maintain the connection between the first differential mechanism and the transmission shaft, and to maintain the connection between the second differential mechanism and the transmission shaft, An output from the first motor and an output from the second motor are transmitted to a drive shaft on the front wheel side and a drive shaft on the rear wheel side via the propeller shaft.

10. The driving device for an electric motor type four-wheel drive vehicle according to claim 6, wherein: The control device controls the first separation mechanism and the second separation mechanism to separate the connection between the first differential mechanism and the transmission shaft and maintain the connection between the second differential mechanism and the transmission shaft. The output from the first motor is transmitted to the drive shaft on the front wheel side, and, The output from the second motor is transmitted to the drive shaft on the rear wheel side.

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