JP2020192922A - vehicle - Google Patents

Abstract

To ensure torque of a motor while preventing overspeed at high-speed traveling.SOLUTION: An ECU executes processing including: a step of executing drive stop control (S112) if it is not during the execution of shut-off control (NO in S100), a vehicle is in a four-wheel drive state (YES in S108), and motor rotational frequency becomes a threshold value Nm(0) or more (YES in S110); a step of executing shut-off control (S114); a step of executing synchronization control (S104) if it is during the shut-off control (YES in S100), and vehicle speed is smaller than a threshold value V(0) (YES in S102); and a step of executing engagement control (S106).SELECTED DRAWING: Figure 4

Description

The present disclosure relates to the control of a vehicle capable of four-wheel drive in which the front wheels and the rear wheels are driven by using different drive sources.

Conventionally, a vehicle capable of four-wheel drive in which the front wheels and the rear wheels are driven by using different drive sources has been known. Specific examples of such a vehicle include a configuration in which the front wheels are driven by an engine and the rear wheels are driven by a motor generator.

For example, Japanese Patent Application Laid-Open No. 2013-153618 (Patent Document 1) describes a hybrid vehicle in which a pair of left and right front wheels are main drive wheels driven by an engine and a pair of left and right rear wheels are auxiliary drive wheels driven by a motor. Disclose.

Japanese Unexamined Patent Publication No. 2013-153618

However, when the rear wheels are driven by a motor, the torque and rotation speed of the motor may be restricted. For example, when the rear wheels are driven by a motor, the motors are arranged around the axles of the rear wheels of the vehicle, and if space is secured in the passenger compartment and luggage compartment, the mounting space of the motor is limited and can be mounted. Motor torque may be constrained. Therefore, for example, when the gear ratio of the speed reducer that can secure the torque at low speed is set, the rotation speed of the motor may be over-rotated at high speed. As a result, the number of revolutions of the motor is restricted, and the maximum speed of the vehicle may be restricted. Further, it is conceivable to change the gear ratio by using a transmission, but if the space in the passenger compartment or the luggage compartment is secured as described above, it may be difficult to mount the transmission.

The present disclosure has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a vehicle equipped with a drive electric motor capable of securing motor torque while preventing over-rotation during high-speed driving. Is to provide.

A vehicle according to a certain aspect of the present disclosure includes a pair of a drive source that generates a driving force in the vehicle, a first drive wheel that drives the vehicle by using the power generated in the drive source, and an electric motor provided separately from the drive source. The second drive wheel, which is composed of the first drive wheel and is provided at a position different from the first drive wheel in the front-rear direction of the vehicle and drives the vehicle using the power generated by the electric motor, and the power of the electric motor of the pair of wheels. A differential gear configured to be transmittable to each, a first state in which power can be transmitted between one of a pair of wheels and the differential gear, and between one wheel and the differential gear. It is provided with a switching device capable of switching to any one of the second states in which power transmission is cut off, and a control device for controlling the switching device. The control device controls the switching device so that the first state is switched to the second state when the rotation speed of the electric motor reaches the threshold value while the vehicle is running.

In this way, when the vehicle is switched to the second state, the relationship that the rotation speed of the electric motor increases in proportion to the increase in the rotation speed of the wheels is eliminated, so that the electric motor is in an over-rotation state when the vehicle is traveling at high speed. Can be suppressed. Therefore, it is possible to select a gear ratio that can secure torque at low speed.

According to the present disclosure, it is possible to provide a vehicle equipped with a drive electric motor capable of securing the torque of a motor while preventing over-rotation during high-speed running.

It is a block diagram which shows an example of the whole structure of a vehicle. It is a figure which shows an example of the structure of the axle on the rear wheel side of a vehicle. It is a figure which shows an example of the structure of the differential gear 42. It is a flowchart which shows an example of the process executed by the ECU. It is a figure for demonstrating the change of the motor rotation speed with respect to a vehicle speed. It is a figure for demonstrating an example of operation of a differential gear. It is a collinear diagram which shows the relationship of the rotation speeds of various gears constituting a differential gear. It is a figure for demonstrating the change of the motor rotation speed with respect to the vehicle speed in the modification. It is a figure for demonstrating an example of the operation of the differential gear in the modification. It is a figure for demonstrating an example of the operation of the differential gear in another modification. It is a figure which shows the modification about the structure of the switching device. It is a figure which shows the other modification about the structure of the switching device.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a block diagram showing an example of the overall configuration of the vehicle 1. As shown in FIG. 1, the vehicle 1 includes an engine 2, a transmission 4, a pair of front wheels 6 and 7, a rear wheel drive device 8, and a pair of rear wheels 10 and 11. The vehicle 1 has four-wheel drive in which the engine 2 is used to drive the front wheels 6 and 7 and the rear wheel drive device 8 is used to drive the rear wheels 10 and 11, and the front wheels 6 and 7 are driven by the engine 2. It is a vehicle capable of driving or rear-wheel drive in which the rear wheels 10 and 11 are driven by using the rear wheel drive device 8.

The engine 2 is an internal combustion engine such as a gasoline engine or a diesel engine, and is a drive source for front wheels 6 and 7, which are drive wheels.

The transmission 4 includes, for example, a transmission and a differential gear (neither shown). The transmission shifts the power of the engine 2 and transmits it to the differential gear. The transmission may be a manual transmission, or may be a stepped or continuously variable automatic transmission. The differential gear in the transmission 4 transmits the power from the transmission to the front wheels 6 and 7 while absorbing the difference in the number of rotations between the front wheels 6 and 7 while the vehicle 1 is turning.

The rear wheel drive device 8 is a drive source for the rear wheels 10 and 11, which are drive wheels, which is composed of a motor generator and a differential gear. The differential gear in the rear wheel drive device 8 transmits the power from the motor generator to the rear wheels 10 and 11 while absorbing the difference in the rotation speeds of the rear wheels 10 and 11 while the vehicle 1 is turning.

FIG. 2 is a diagram showing an example of the configuration of the axle on the rear wheel side of the vehicle 1. That is, FIG. 2 shows the configuration of the axle on the rear wheel side when viewed from the rear side of the vehicle 1. As shown in FIG. 2, on the axle on the rear wheel side of the vehicle 1, a rear wheel drive device 8, a switching device 40, drive shafts 16 and 26, upper arms 12, 22 and lower arms 14, 24 are provided. Knuckles 32 and 34 are provided.

The rear wheel drive device 8 includes a differential gear 42, a reduction mechanism 44, and a motor generator 46. The speed reduction mechanism 44 reduces the rotation of the motor generator 46 by a predetermined gear ratio.

The motor generator 46 is a rotary electric machine driven by using electric power supplied from the battery 50 via the PCU (Power Control Unit) 52. The motor generator 46 is, for example, a three-phase AC rotary electric machine. The battery 50 includes, for example, a secondary battery such as a lithium ion secondary battery or a nickel hydrogen secondary battery, but for example, a power storage device such as a capacitor can also be applied. The PCU 52 includes an inverter that converts the DC power of the battery 50 into AC power. The PCU 52 may include a converter capable of adjusting the voltage in addition to the inverter. The PCU 52 operates in response to a control signal from the ECU (Electronic Control Unit) 100.

One end of the drive shaft 26 is connected to the differential gear 42 of the rear wheel drive device 8. The other end of the drive shaft 26 is rotatably supported by a bearing (not shown) provided on the knuckle 34 and is connected to the rear wheel 11. One end of the upper arm 22 is connected to the upper part of the knuckle 34. One end of the lower arm 24 is connected to the lower part of the knuckle 34. The other end of the upper arm 22 and the other end of the lower arm 24 are both connected to the vehicle body (not shown) of the vehicle 1.

Further, one end of the drive shaft 16 is connected to the differential gear of the rear wheel drive device 8 with a switching device 40 interposed therebetween. The other end of the drive shaft 16 is rotatably supported by a bearing (not shown) provided on the knuckle 32 and is connected to the rear wheel 10. One end of the upper arm 12 is connected to the upper part of the knuckle 32. One end of the lower arm 14 is connected to the lower part of the knuckle 32. The other end of the upper arm 12 and the other end of the lower arm 24 are both connected to the vehicle body of the vehicle 1.

The rear suspension is composed of upper arms 12, 22, lower arms 14, 24 and knuckles 32, 34.

The switching device 40 switches from one of a transmission state in which power can be transmitted between the differential gear 42 and the drive shaft 16 and a cutoff state in which power transmission is cut off to the other state. It is configured to be possible. The switching device 40 is composed of, for example, a dog clutch. The switching device 40 operates in response to a control signal from the ECU 100, for example.

The ECU 100 includes, for example, a CPU (Central Processing Unit), a memory, and an input / output buffer (none of which is shown). The memory includes ROM (Read Only Memory), RAM (Random Access Memory), and rewritable non-volatile memory. Various controls are executed by the CPU executing the program stored in the memory (for example, ROM). The ECU 100 sets each device (engine 2, rear wheel drive device 8 or PCU 52) so that the vehicle 1 is in a desired operating state based on, for example, a signal received from each sensor and a map and a program stored in a memory. Control. The various controls performed by the ECU 100 are not limited to processing by software, but can also be processed by dedicated hardware (electronic circuits).

Wheel rotation speed sensors 18 and 28 and motor rotation speed sensors 48 are connected to the ECU 100. The wheel rotation speed sensors 18 and 28 detect, for example, the rotation speeds of the timing rotors provided at one ends of the drive shafts 16 and 26 (hereinafter, referred to as wheel rotation speeds Na and Nb, respectively). The wheel rotation speed sensors 18 and 28 transmit signals indicating the detected wheel rotation speeds Na and Nb to the ECU 100. The ECU 100 calculates the vehicle speed V using, for example, the received wheel rotation speeds Na and Nb. The motor rotation speed sensor 48 is provided in the rear wheel drive device 8 and detects the rotation speed (hereinafter, referred to as the motor rotation speed) Nm of the motor generator 46. The motor rotation speed sensor 48 transmits a signal indicating the detected motor rotation speed Nm to the ECU 100. The motor rotation speed sensor 48 is composed of, for example, a resolver or the like.

FIG. 3 is a diagram showing an example of the configuration of the differential gear 42. As shown in FIG. 3, the differential gear 42 is composed of a ring gear 42a, pinion gears 42b and 42c, a right side gear 42d, a left side gear 42e, a right side shaft 42f, and a left side shaft 42g.

The ring gear 42a meshes with the gears constituting the reduction mechanism 44. Therefore, the ring gear 42a receives the power of the motor generator 46 and rotates on the same rotation shaft as the rotation shaft of the right side shaft 42f and the rotation shaft of the left side shaft 42g. The ring gear 42a has a U-shape, both ends of which are fixed to the ring gear 42a, and a holding member for holding the pinion gears 42b and 42c is provided at the center. The holding member is formed so as to pass through the center of the rotation shaft of the ring gear 42a. The pinion gears 42b and 42c are rotatably held at positions facing each other across the rotation shaft of the ring gear 42a.

The right side gear 42d is connected to one end of the right side shaft 42f and rotates about the same rotation axis as the rotation axis of the right side shaft 42f. The right side gear 42d is arranged so as to mesh with both the pinion gears 42b and 42c.

The left side gear 42e is connected to one end of the left side shaft 42g and rotates about the same rotation axis as the rotation axis of the left side shaft 42g. The left side gear 42e is arranged at a position where it meshes with both the pinion gears 42b and 42c and faces the right side gear 42d.

The other end of the right side shaft 42f is connected to the switching device 40. The other end of the left side shaft 42g is connected to the drive shaft 26.

In the vehicle 1 having the above configuration, when the rear wheels 10 and 11 are driven by the motor generator 46, the torque and the rotation speed of the motor generator 46 may be restricted. For example, when the rear wheels 10 and 11 are driven by the motor generator 46, the motor generator 46 is arranged around the axles of the rear wheels 10 and 11 of the vehicle 1, and if space is secured in the passenger compartment and luggage compartment, The mounting space of the motor generator 46 is limited, and the torque of the motor that can be mounted may be limited. Therefore, for example, when the gear ratio of the reduction mechanism 44 that can secure the torque at low speed is set, the rotation speed of the motor may be over-rotated during high-speed running. As a result, the rotation speed of the motor generator 46 is restricted, and the maximum speed of the vehicle 1 may be restricted. Further, it is conceivable to change the gear ratio by using a transmission, but if the space in the passenger compartment or the luggage compartment is secured as described above, it may be difficult to mount the transmission.

Therefore, in the present embodiment, the ECU 100 starts from the transmission state when the motor rotation speed Nm reaches the threshold value Nm (0) while the vehicle 1 using the engine 2 and the motor generator 46 is traveling. It is assumed that the switching device 40 is controlled so that it can be switched to the cutoff state.

In this way, the relationship that the motor rotation speed Nm increases in proportion to the increase in the rotation speeds Na and Nb (that is, the vehicle speed V) of the rear wheels 10 and 11 when the switch to the cutoff state is eliminated is eliminated. It is possible to prevent the motor generator 46 from being over-rotated when the vehicle 1 is traveling at high speed. Therefore, it is possible to select a gear ratio that can secure torque at low speed.

Hereinafter, an example of the control process executed by the ECU 100 will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the control process executed by the ECU 100.

In step 100 (hereinafter, step is referred to as S) 100, the ECU 100 determines whether or not the shutoff control for putting the switching device 40 into the shutoff state is being executed. The ECU 100 determines that the cutoff control is being executed, for example, when the flag indicating that the cutoff control is being executed is on. When it is determined that the cutoff control is being executed (YES in S100), the process is transferred to S102.

In S102, the ECU 100 determines whether or not the vehicle speed V is smaller than the threshold value V (0). For example, the ECU 100 may calculate the vehicle speed V from any of the rotation speeds Na and Nb of the rear wheels 10 and 11, or may calculate the vehicle speed V from the average value of the rotation speeds Na and Nb. Good. The threshold value V (0) is, for example, the lower limit of the vehicle speed range in which the motor generator 46 is determined to be in the over-rotation state when the switching device 40 is in the transmission state. When it is determined that the vehicle speed V is smaller than the threshold value V (0) (YES in S102), the process is transferred to S104.

In S104, the ECU 100 executes synchronous control. The ECU 100 adjusts the rotation speed of the motor generator 46 so that the magnitude of the difference between the rotation speed on the drive shaft 16 side and the rotation speed on the differential gear 42 side of the dog clutch constituting the switching device 40 is equal to or less than the threshold value. Control.

In S106, the ECU 100 executes engagement control that brings the switching device 40 into the transmission state. For example, the ECU 100 controls the switching device 40 so that the switching device 40 is in the transmission state after being in the synchronous state by the synchronous control. At this time, the ECU 100 turns off, for example, the flag indicating that the cutoff control is being executed.

If it is determined in S100 that the cutoff control is not being executed (NO in S100), the process is transferred to S108.

In S108, the ECU 100 determines whether or not the vehicle 1 is in a four-wheel drive state using the engine 2 and the rear wheel drive device 8. The ECU 100 determines that the vehicle 1 is in the four-wheel drive state when, for example, the driving area of the vehicle 1 specified by the vehicle speed, the accelerator opening, or the like is within the driving area in which the driving state is the four-wheel drive state. Alternatively, it may be determined that the vehicle 1 is in a four-wheel drive state when the vehicle 1 is running and both the engine 2 and the motor generator 46 are controlled to be in the operating state. May be good. When it is determined that the vehicle 1 is in the four-wheel drive state (YES in S108), the process is transferred to S110.

In S110, the ECU 100 determines whether or not the motor rotation speed Nm is equal to or greater than the threshold value Nm (0). The threshold value Nm (0) is a lower limit value of the rotation speed range in which the motor rotation speed Nm is in an over-rotation state, and is, for example, a predetermined value set experimentally or designly. When it is determined that the motor rotation speed Nm is equal to or higher than the threshold value Nm (0) (YES in S110), the process is transferred to S112.

At S112, the ECU 100 executes drive stop control. The ECU 100 controls the PCU 52 so that the motor rotation speed Nm becomes zero.

At S114, the ECU 100 executes cutoff control. The ECU 100 controls the switching device 40 so that the switching device 40 is shut off at the timing when the motor rotation speed Nm becomes zero, for example. At this time, the ECU 100 turns on the flag indicating that the cutoff control is being executed.

When it is determined in S102 that the vehicle speed is equal to or higher than the threshold value V (0) (NO in S102), when it is determined in S108 that the vehicle 1 is not in the four-wheel drive state (NO in S108). ), And when it is determined in S110 that the motor rotation speed Nm is smaller than the threshold value Nm (0) (NO in S110), the process is terminated.

The operation of the vehicle 1 according to the present embodiment based on the above structure and the flowchart will be described with reference to FIGS. 5, 6 and 7.

FIG. 5 is a diagram for explaining a change in the motor rotation speed with respect to the vehicle speed. The vertical axis of FIG. 5 indicates the motor rotation speed. The horizontal axis in FIG. 5 indicates the vehicle speed. It is assumed that the vehicle 1 is, for example, traveling straight, is in a four-wheel drive state using the engine 2 and the motor generator 46, and is in a transmission state of the switching device 40. Further, Vmax indicates the maximum vehicle speed of the vehicle 1.

LN1 (thick solid line) in FIG. 5 shows the change in the motor rotation speed Nm. LN2 (double line) in FIG. 5 shows changes in the rotation speeds of the drive shafts 16 and 26. LN3 (dashed line) in FIG. 5 shows the change in the rotation speed of the right side gear 42d (see FIG. 5) of the differential gear 42.

Whether or not the motor rotation speed Nm is equal to or higher than the threshold value Nm (0) because the cutoff control is not being executed (NO in S100) and the vehicle 1 is in a four-wheel drive state (NO in S108). It is determined (S110).

As shown in LN1 of FIG. 5, when the motor rotation speed Nm is smaller than the threshold value Nm (0) (NO in S110), the transmission state of the switching device 40 is maintained, so that the four-wheel drive state is maintained. Is continued. For example, when the accelerator opening is a constant opening, the vehicle speed V increases and the motor rotation speed Nm also increases until the vehicle speed reaches the accelerator opening.

Then, when the motor rotation speed Nm reaches the threshold value Nm (0) (YES in S110), the drive stop control is executed (S112), and the PCU 52 controls the motor rotation speed Nm to become zero. Will be done. Then, the cutoff control is executed (S114), and the switching device 40 is controlled to be in the cutoff state.

On the other hand, as shown in LN2 of FIG. 5, the rotation speeds of the drive shafts 16 and 26 increase in proportion to the increase in the rotation speeds of the rear wheels 10 and 11. Further, as shown in LN3 of FIG. 5, the rotation direction of the right side gear 42d of the differential gear 42 is opposite to the rotation direction of the rear wheel 10 due to the switching device 40 being shut off, and the rear wheel 10 is rotated. The magnitude of the rotation speed increases in proportion to the increase in the rotation speed.

FIG. 6 is a diagram for explaining an example of the operation of the differential gear 42. For example, when the vehicle 1 is traveling forward and the switching device 40 is controlled to be in a cutoff state, the differential gear 42 operates as follows. That is, the left side shaft 42g rotates as the rear wheels 11 drive the vehicle 1. At this time, the switching device 40 is shut off and the ring gear 42a is stopped. Therefore, the rotational force of the left side shaft 42g is transmitted to the right side shaft 42f by reversing the rotational direction by the pinion gears 42b and 42c. Therefore, the rotation direction of the right side shaft 42f is opposite to the rotation direction of the left side shaft 42g.

When the ring gear 42a is in the stopped state, the rotation speed of the right side shaft 42f is about the same as the rotation speed of the left side shaft 42g. Therefore, as the rotation speed of the rear wheel 10 further increases, the rotation speed of the right side gear 42d increases in proportion to the increase in the rotation speed of the left side gear 42e.

If the vehicle speed V is lower than the threshold value V (0) during execution of the cutoff control (YES in S100) (S102YES), the motor generator 46 is operated and synchronous control is executed. (S104). Then, the switching device 40 is controlled so as to be in the transmission state by executing the engagement control at the timing when the rotation speed on the drive shaft 16 side and the rotation speed on the right side shaft 42f are synchronized in the switching device 40. , The vehicle 1 is in a four-wheel drive state (S106).

FIG. 7 is a collinear diagram showing the relationship between the rotation speeds of the various gears constituting the differential gear 42. The collinear diagram on the left side of FIG. 7 is a collinear diagram showing the relationship between the rotation speed of the left side gear 42e, the rotation speed of the ring gear 42a, and the rotation speed of the right side gear 42d during the cutoff control. The collinear diagram on the right side of FIG. 7 is a collinear diagram showing the relationship between the rotation speed of the left side gear 42e, the rotation speed of the ring gear 42a, and the rotation speed of the right side gear 42d during engagement control. It is assumed that the vehicle 1 is traveling forward.

As shown by the broken line in the collinear diagram on the left side of FIG. 7, when the switching device 40 is in the transmission state, the ring gear 42a, the left side gear 42e, and the right side gear 42d rotate at the same rotation speed. When the motor rotation speed Nm becomes the threshold value Nm (0) or more, the motor generator 46 is stopped and the switching device 40 is shut off, as shown by the solid line in the collinear diagram on the left side of FIG. In addition, the rotation speed of the ring gear 42a becomes zero. Further, the rotation direction of the right side gear 42d is opposite. At this time, the magnitude of the rotation speed of the left side gear 42e and the magnitude of the rotation speed of the right side gear 42d are about the same.

On the other hand, as shown by the solid line in the collinear diagram on the right side of FIG. 7, when the vehicle speed V is lower than the threshold value V (0), the rotation speed of the ring gear 42a is increased by operating the motor generator 46. At the same time, the rotation speed of the right side gear 42d increases. Then, as shown by the broken line in the collinear diagram on the right side of FIG. 6, when the rotation speed of the right side gear 42d reaches the same rotation speed as the rotation speed of the left side gear 42e (= rotation speed of the rear wheel 10), the switching device 40 changes from the cutoff state to the transmission state. As a result, the vehicle 1 is in a four-wheel drive state.

As described above, according to the vehicle 1 according to the present embodiment, when the switching device 40 is switched to the cutoff state, the relationship that the motor rotation speed Nm increases in proportion to the increase in the vehicle speed V is eliminated. It is possible to prevent the motor generator 46 from being over-rotated when the vehicle 1 is traveling at high speed. Therefore, it is possible to select a gear ratio that can secure torque at low speed. Therefore, it is possible to provide a vehicle equipped with a drive electric motor capable of securing the torque of the motor while preventing over-rotation during high-speed running.

Hereinafter, modification examples will be described.
In the above-described embodiment, the switching device 40 is put into a cut-off state, and the PCU 52 is controlled so that the motor rotation speed Nm becomes zero by the drive stop control. The PCU 52 may be controlled so that the motor rotation speed Nm becomes a target rotation speed set according to the vehicle speed.

For example, in the ECU 100, when the vehicle 1 is in a four-wheel drive state and the motor rotation speed Nm exceeds the threshold value Nm (0), the switching device 40 is controlled so as to be in a cutoff state, and the motor rotation speed is controlled. The PCU 52 may be controlled so that Nm becomes a target rotation speed equal to or less than the threshold value Nm (0). For example, the ECU 100 sets a target rotation speed at which the energy loss in the motor generator 46 is small and the lubricating oil in the motor generator 46 is agitated by the rotation of the motor generator 46 to maintain an appropriate lubrication function. Set. The ECU 100 sets, for example, a target rotation speed according to the vehicle speed. More specifically, the ECU 100 sets the target rotation speed so that the value increases as the vehicle speed V increases, for example, using a map or the like. The ECU 100 controls the PCU 52 so as to reach the set target rotation speed. The process of the ECU 100 in the modified example differs from the process shown in FIG. 4 in that the drive control of the motor generator 46 is executed instead of the drive stop control, and the other processes are shown in FIG. Same as processing. Therefore, the detailed explanation will not be repeated.

Hereinafter, the operation of the vehicle 1 in the modified example will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram for explaining a change in the motor rotation speed Nm with respect to the vehicle speed V in the modified example. The vertical axis of FIG. 8 indicates the motor rotation speed Nm. The horizontal axis of FIG. 8 indicates the vehicle speed V. LN4 (solid line) in FIG. 8 shows the change in the motor rotation speed Nm. LN5 (double line) in FIG. 8 shows the change in the rotation speed of the drive shafts 16 and 26. LN6 (dashed line) in FIG. 8 indicates the rotation speed of the right side gear 42d. LN7 (broken line) in FIG. 8 indicates the rotation speed of the pinion gears 42b and 42c.

As shown in LN4 of FIG. 8, when the motor rotation speed Nm becomes the threshold value Nm (0) or more, the cutoff control is executed and the rotation speed of the motor generator 46 is controlled to reach the target rotation speed. .. As the target rotation speed after executing the cutoff control, for example, a value lower than the threshold value Nm (0) by a predetermined value is set, and a higher value is set in proportion to the subsequent increase in vehicle speed. ..

As shown in LN5 of FIG. 8, the rotation speeds of the drive shafts 16 and 26 increase in proportion to the increase in the rotation speeds of the rear wheels 10 and 11.

As shown in LN6 and LN7 of FIG. 8, the magnitude of the rotation speed of the right side gear 42d and the magnitude of the rotation speed of the pinion gears 42b and 42c are the difference between the rotation speed of the ring gear 42a and the rotation speed of the drive shaft 26, respectively. The number of revolutions corresponds to the gear ratio. Therefore, the magnitude of the rotation speed of the right side gear 42d and the magnitude of the rotation speed of the pinion gears 42b and 42c both increase in proportion to the increase in the rotation speed of the rear wheel 10.

FIG. 9 is a diagram for explaining an example of the operation of the differential gear 42 in the modified example. The configuration of the differential gear 42 shown in FIG. 9 is the same as the configuration of the differential gear 42 shown in FIG. Therefore, the detailed explanation will not be repeated.

For example, when the vehicle 1 is traveling forward and the switching device 40 is controlled to be in a cutoff state, the differential gear 42 operates as follows. That is, the left side shaft 42g rotates as the rear wheels 11 drive the vehicle 1. At this time, the switching device 40 is shut off, and the PCU 52 is controlled so that the motor rotation speed Nm becomes the target rotation speed. Therefore, the rotation speeds of the pinion gears 42b and 42c and the rotation speeds of the right side gear 42d are the rotation speeds corresponding to the difference between the rotation speeds of the left side shaft 42g and the rotation speeds of the ring gear 42a, respectively. FIG. 9 shows, as an example, a case where the rotation direction of the right side gear 42d is the same as the rotation direction of the left side gear 42e.

In this way, during execution of the cutoff control, the motor rotation speed Nm is controlled to reach the target rotation speed, so that the energy loss in the motor generator 46 is suppressed and the lubrication function in the differential gear 42 is maintained. can do.

Further, in the above-described embodiment, the switching device 40 is put into a cut-off state, and the PCU 52 is controlled so that the motor rotation speed Nm becomes zero by the drive stop control. However, the switching device 40 is put into a cut-off state. At the same time, the motor generator 46 may be operated according to the acceleration / deceleration of the vehicle 1.

FIG. 10 is a diagram for explaining an example of the operation of the differential gear 42 in another modified example. The configuration of the differential gear 42 shown in FIG. 10 is the same as the configuration of the differential gear 42 shown in FIG. Therefore, the detailed explanation will not be repeated.

For example, when the vehicle 1 is traveling forward and the switching device 40 is controlled to be in a cutoff state, when the vehicle 1 is suddenly accelerated or decelerated, the rotation speed of the left side gear is changed to the vehicle. It fluctuates according to the sudden acceleration or deceleration of 1. At this time, as shown in FIG. 10, the rotation shafts of the pinion gears 42b and 42c are caused by the rotational inertia forces of the pinion gears 42b and 42c, the right side gears 42d, and the parts connected to the right side shaft 42f of the switching device 40. A reaction force is generated in the engine, and the generated reaction force may act in a direction of suppressing the rotation of the left side shaft 42g.

Therefore, the motor generator 46 may be operated so that the braking force does not act on the left side shaft 42g. The ECU 100 calculates, for example, the acceleration of the vehicle 1, sets the rotation direction and torque magnitude of the motor generator 46 from the calculated sign and magnitude of the acceleration, and sets the magnitude for the set rotation direction. The PCU 52 is controlled so that the torque is output from the motor generator 46. For example, the ECU 100 controls the PCU 52 so that the motor generator 46 outputs a torque corresponding to the above-mentioned rotational inertial force in the same direction as the increase direction of the rotation speed of the left side shaft 42g when the vehicle 1 is accelerated.

By doing so, it is possible to suppress the action of a braking force that suppresses rotation on the rear wheels 11 connected to the left side shaft 42g during acceleration / deceleration of the vehicle 1, so that the straightness of the vehicle 1 deteriorates. Can be suppressed.

Further, in the above-described embodiment, the switching device 40 has been described as being provided between the right side shaft 42f and one end of the drive shaft 16 and outside the rear wheel drive device 8. It is not limited to the position.

FIG. 11 is a diagram showing a modified example of the configuration of the switching device 40. As shown in FIG. 11, the switching device 40 may be provided, for example, between the right side shaft 42f and one end of the drive shaft 16 and inside the rear wheel drive device 8. In FIG. 11, the same reference numerals are given to the same configurations other than the above-described configurations, and the functions thereof are also the same. Therefore, the detailed explanation will not be repeated.

FIG. 12 is a diagram showing another modification of the configuration of the switching device 40. As shown in FIG. 12, the switching device 40 may be provided inside the knuckle 34 and between the other end of the drive shaft 16 and the wheel hub 36. The wheel hub 36 is connected to the rear wheel 10 and is rotatably supported by a bearing provided in the knuckle 34. In FIG. 12, the same reference numerals are given to the same configurations other than the above-described configurations, and the functions thereof are also the same. Therefore, the detailed explanation will not be repeated.

Further, in the above-described embodiment, when the vehicle 1 is in the four-wheel drive state, the switching device 40 is shut off when the motor rotation speed Nm becomes the threshold value Nm (0) or more. The vehicle 1 is not particularly limited to the case where the vehicle 1 is in a four-wheel drive state. For example, the vehicle 1 is traveling using, for example, at least one of the engine 2 and the motor generator 46, and When the motor rotation speed Nm becomes the threshold value Nm (0) or more, the switching device 40 may be shut off.

In addition, the above-mentioned modification may be carried out by appropriately combining all or a part thereof.
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 vehicle, 2 engine, 4 transmission, 6,7 front wheel, 8 rear wheel drive, 10,11 rear wheel, 12,22 upper arm, 14,24 lower arm, 16,26 drive shaft, 18,28 wheel speed sensor , 32, 34 knuckle, 36 wheel hub, 40 switching device, 42 differential gear, 42a ring gear, 42b, 42c pinion gear, 42d right side gear, 42e left side gear, 42f right side shaft, 42g left side shaft, 44 reduction mechanism, 46 motor Generator, 48 motor speed sensor, 50 battery, 52 PCU, 100 ECU.

Claims (1)

A drive source that generates driving force in the vehicle,
A first drive wheel that drives the vehicle using the power generated by the drive source,
An electric motor provided separately from the drive source and
A second drive wheel composed of a pair of wheels, provided at a position different from that of the first drive wheel in the front-rear direction of the vehicle, and driving the vehicle using the power generated by the electric motor.
A differential gear configured to transmit the power of the electric motor to each of the pair of wheels.
The first state in which power can be transmitted between one of the pair of wheels and the differential gear and the transmission of power between the one wheel and the differential gear are cut off. A switching device that can switch to either of the second states and
A control device for controlling the switching device is provided.
The control device controls the switching device so that when the rotation speed of the electric motor reaches a threshold value while the vehicle is traveling, the switching device is switched from the first state to the second state.

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