JP3870943B2 - Vehicle driving force control device - Google Patents

Description

  The present invention relates to a vehicle driving force control apparatus in which a clutch is interposed between a motor and wheels.

Conventionally, as a driving force control device for a vehicle in which a front wheel is driven by an engine and a rear wheel can be driven by an electric motor and a clutch is interposed in a torque transmission path from the motor to the rear wheel, for example, Patent Document 1 Some are listed. During four-wheel drive, the clutch is controlled to be connected and the motor is controlled to a predetermined driving torque.
JP-A-11-243608

By the way, when the rear wheel suddenly decelerates due to sudden braking or the like when driving the four wheels with the clutch connected and the motor driving the rear wheel, torque transmitted from the motor to the clutch and transmitted from the rear wheel to the clutch. Torque becomes reverse torque, and excessive torque may be applied to the clutch due to inertia on the motor side. If an excessive torque is applied to the clutch, the life of the clutch may be reduced. In particular, in the case of a mechanical clutch such as a dog clutch or a one-way clutch, the life is shortened as compared with a friction clutch.
The present invention has been made paying attention to the above points, and provides a vehicle driving force control device capable of suppressing a reduction in the life of a clutch interposed between a motor and wheels.

In order to solve the above problems, the present invention includes a motor, wheels driven by the motor, and a clutch interposed in a power transmission path from the motor to the wheels, and the clutch is connected while the motor is driven. A driving force control device for a vehicle that controls to a state,
Clutch torque state determining means for detecting or estimating that the transmission torque of the clutch has approached a limit torque based on the specifications of the clutch;
Motor torque limiting means for limiting the driving torque of the motor when it is determined that the transmission torque of the clutch has approached the limit torque based on detection or estimation of the clutch torque state determination means ,
For example, if it is determined that the torque transmitted from the wheel to the clutch approaches the limit torque and the clutch transmission torque approaches the limit torque, the motor torque limiting means converts the motor drive torque to a torque in the reverse rotation direction. It is characterized by doing.

  According to the present invention, when the torque applied to the clutch is excessive, the motor drive torque is limited to be small or negative, so that the clutch transmission torque is suppressed. As a result, it is possible to prevent an excessive torque from being applied to the clutch, and to shorten the load time of the excessive torque, thereby suppressing a decrease in the life of the clutch.

Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a system configuration of a vehicle according to the present embodiment.
As shown in FIG. 1, in the vehicle of this embodiment, left and right front wheels 1L and 1R are main drive wheels driven by an engine 2 (main drive source) that is an internal combustion engine, and left and right rear wheels 3L and 3R are A driven wheel that can be driven by the motor 4.
That is, the output torque Te of the engine 2 is transmitted to the left and right front wheels 1L, 1R through the transmission 30 and the difference gear 31.
The transmission 30 is provided with shift position detecting means 32 for detecting the current shift range, and the shift position detecting means 32 outputs the detected shift position signal to the 4WD controller 8.

  A main throttle valve 15 and a sub-throttle valve 16 are interposed in the intake pipe line 14 (for example, an intake manifold) of the engine 2. The throttle opening of the main throttle valve 15 is adjusted and controlled in accordance with the amount of depression of an accelerator pedal 17 that is an accelerator opening instruction device (acceleration instruction operation unit). The main throttle valve 15 is mechanically linked to the amount of depression of the accelerator pedal 17 or the engine throttle valve 15 detects the amount of depression of the accelerator pedal 17 (accelerator opening). The controller 18 electrically adjusts and controls the throttle opening. The detected depression amount value of the accelerator sensor 40 is also output to the 4WD controller 8.

  The sub-throttle valve 16 is adjusted and controlled by a rotation angle corresponding to the number of steps using the step motor 19 as an actuator. The rotation angle of the step motor 19 is adjusted and controlled by a drive signal from the motor controller 20. The sub-throttle valve 16 is provided with a throttle sensor, and the number of steps of the step motor 19 is feedback-controlled based on the detected throttle opening value detected by the throttle sensor. Here, by adjusting the throttle opening of the sub-throttle valve 16 to be less than or equal to the opening of the main throttle valve 15, the output torque of the engine 2 is controlled independently of the driver's operation of the accelerator pedal. Can do.

Further, an engine speed detection sensor 21 that detects the speed of the engine 2 is provided, and the engine speed detection sensor 21 outputs the detected signal to the engine controller 18 and the 4WD controller 8.
Reference numeral 34 denotes a brake pedal that constitutes a braking instruction operation unit, and a stroke amount of the brake pedal 34 is detected by a brake stroke sensor 35. The brake stroke sensor 35 outputs the detected brake stroke amount to the braking controller 36 and the 4WD controller 8.

  The braking controller 36 controls the braking force acting on the vehicle through the braking devices 37FL, 37FR, 37RL, 37RR such as disc brakes equipped on the wheels 1L, 2R, 3L, 3R according to the input brake stroke amount. . Further, when a signal from an ABS device described later is input, the braking controller 36 controls the braking force regardless of the input brake stroke amount.

Reference numeral 42 denotes an ABS device that calculates anti-skit brake control, and outputs a command value to the brake controller 36. The ABS device is an example of an automatic braking control device, and examples of the automatic braking control device include a VDC device and a TCS device.
Further, a part of the rotational torque Te of the engine 2 is transmitted to the generator 7 through the endless belt 6, so that the generator 7 is obtained by multiplying the rotational speed Ne of the engine 2 by the pulley ratio. Rotate at Nh.

  As shown in FIG. 2, the generator 7 includes a voltage regulator 22 (regulator) for adjusting the output voltage V, and the generator control command value c <b> 1 (duty ratio) is controlled by the 4WD controller 8. Thus, the voltage V generated through the field current Ifh is controlled. That is, the voltage regulator 22 receives the generator control command c1 from the 4WD controller 8, adjusts the field current Ifh of the generator 7 to a value corresponding to the generator control command c1, and outputs the generator 7 The voltage V can be detected and output to the 4WD controller 8. The rotational speed Nh of the generator 7 can be calculated from the rotational speed Ne of the engine 2 based on the pulley ratio.

The electric power generated by the generator 7 can be supplied to the motor 4 via the electric wire 9. A junction box 10 is provided in the middle of the electric wire 9. The drive shaft of the motor 4 can be connected to the rear wheels 3L and 3R via the speed reducer 11 and the clutch 12. Reference numeral 13 represents a differential.
In addition, a current sensor 23 is provided in the junction box 10, and the current sensor 23 detects the current value Ia of the electric power supplied from the generator 7 to the motor 4, and outputs the detected armature current signal to 4WD. Output to the controller 8. In addition, a voltage value (voltage of the motor 4) flowing through the electric wire 9 is detected by the 4WD controller 8. Reference numeral 24 denotes a relay, and the cutoff and connection of the voltage (current) supplied to the motor 4 is controlled by a command from the 4WD controller 8.

  In addition, the field current Ifm of the motor 4 is controlled by a command from the 4WD controller 8, and the drive torque is adjusted to the target motor torque by adjusting the field current Ifm. Reference numeral 25 denotes a thermistor that measures the temperature of the motor 4. Furthermore, a motor rotation speed sensor 26 for detecting the rotation speed Nm of the drive shaft of the motor 4 is provided, and the motor rotation speed sensor 26 outputs the detected rotation speed signal of the motor 4 to the 4WD controller 8.

Further, the clutch 12 of the present embodiment is a clutch that is connected and disconnected by a mechanical mechanism as described below, and the electromagnetic clutch unit 106 is connected or disconnected according to a clutch control command from the 4WD controller 8. In this state, connection / disconnection control of the clutch 12 is performed.
Next, the mechanism and configuration of the clutch 12 will be described with reference to FIG. 3 and FIG. 4 which is a schematic diagram.

  The outer ring member 101 that is the first rotating member and the inner ring member 100 that is the second rotating member are arranged coaxially, and are related to the space between the outer diameter surface of the inner ring member 100 and the inner diameter surface of the outer ring member 101. A plurality of rollers 102, which are conjuncts, are inserted along the circumferential direction. The inner ring surface of the outer ring member 101 is a cylindrical surface. On the outer diameter surface of the inner ring member 100, cam surfaces 100a are formed at predetermined intervals along the circumferential direction. The cam surface 100a is, for example, a flat surface, so that an engagement space 103 is formed between the cam surface 100a and the inner diameter surface of the outer ring member 101 opposed in the radial direction. The wedge space 103a becomes narrower as it goes to both sides. If the engagement space 103 is formed with a wedge space 103a (a space where the facing distance between the inner ring member 100 and the outer ring member 102 is smaller than that of the roller 102) on both sides in the circumferential direction, the cam surface 100a has a concave shape or the like. Other contour-shaped surfaces may be used. Further, the adjacent cam surfaces 100a do not need to be continuous, and may be formed so as to be opened at a predetermined interval. The rollers 102 are disposed in the engagement spaces 103, and the plurality of rollers 102 are accommodated in the pockets of the cage 104 interposed between the inner ring member 100 and the outer ring member 101. Has been. That is, the distance between the rollers 102 is regulated by the cage 104, that is, the circumferential position is regulated. The cage 104 is connected to the inner ring member 100 via a switch spring 105. The switch spring 105 can exert a spring force in the circumferential direction with respect to the cage 104, and the position of each roller 102 accommodated in the pocket of the cage 104 corresponds to the corresponding engagement space 103. The retainer 104 is imparted and supported toward a neutral position arranged at a substantially central position.

  Further, the clutch 12 is provided with an electromagnetic clutch portion 106 that constitutes a clutch operating portion, and when the energization is turned on (clutch control current on), the retainer 104 is connected to the outer ring member 101 (the outer ring member 101). The retainer 104 is fixed to the outer ring member 101, and the energization is turned off (clutch control current is turned off), whereby the retainer 104 and the outer ring member 101 are disconnected (the retainer 104 is released from the outer ring member 101). . Reference numeral 107 represents an armature, reference numeral 108 represents a roller 102, and reference numeral 109 represents an electromagnetic coil.

The outer ring member 101 is connected to the drive shaft side of the motor 4, and the inner ring member 100 is connected to the rotating shaft on the wheel side.
In the clutch 12 of the above mechanism, when the retainer 104 is in the released state, the roller 102 is held at the neutral position of the engagement space 103 by the action of the switch spring 105, so that the inner ring member 100 and the outer ring Torque is not transmitted between the member 101 and the roller 102, and the inner ring member 100 and the outer ring member 101 are rotatable independently of each other.

  On the other hand, when the cage 104 is fixed, if the phase difference occurs between the inner ring member 100 and the cage 104 due to the relative rotational difference between the inner ring member 100 and the outer ring member 101, the switch The roller 102 moves to one of the left and right wedge spaces 103a against the elastic force of the spring 105 and engages with one of the wedge spaces 103a. That is, the roller 102 engages between the inner ring member 100 and the outer ring member 101. Thus, torque can be transmitted between the inner ring member 100 and the outer ring member 101. The torque transmission direction differs depending on whether the roller 102 is engaged with the left or right wedge space 103a.

That is, in the clutch 12 having the above-described configuration, connection / disconnection of the clutch 12 is controlled by turning on / off the energization of the electromagnetic clutch unit 106 (on / off of the clutch control current).
Each wheel 1L, 1R, 3L, 3R is provided with a wheel speed sensor 27FL, 27FR, 27RL, 27RR. Each wheel speed sensor 27FL, 27FR, 27RL, 27RR outputs a pulse signal corresponding to the rotation speed of the corresponding wheel 1L, 1R, 3L, 3R to the 4WD controller 8 as a wheel speed detection value.

  Reference numeral 41 denotes a drive mode switch that designates either the two-wheel drive mode or the four-wheel drive mode, and outputs the designated drive mode information to the 4WD controller 8. Here, the drive mode switch 41 is not limited to the case where it is selected by direct instruction from the driver. Depending on other four-wheel drive conditions, either the two-wheel drive mode or the four-wheel drive mode may be selected. For example, the front wheels 1L and 1R may be set so that an acceleration slip exceeding a predetermined value occurs or the four-wheel drive mode is automatically set for a predetermined time at the time of starting.

As shown in FIG. 5, the 4WD controller 8 includes a 4WD controller main body 8A, a target motor torque calculation unit 8B, a motor torque limiting unit 8C, a generator control unit 8D, a relay control unit 8E, a motor control unit 8F, and a clutch control unit. 8G is provided. In FIG. 5, a clutch protection check unit 8H, which is a processing unit used in an embodiment described later, is also shown.
The generator control unit 8D adjusts the field current Ifh by outputting the generator command value c1 of the generator 7 while monitoring the generated voltage V of the generator 7 through the voltage regulator 22.

The relay control unit 8E controls interruption / connection of power supply from the generator 7 to the motor 4.
The motor control unit 8F adjusts the torque of the motor 4 to a required value by adjusting the field current Ifm of the motor 4.
The clutch control unit 8G controls the state of the clutch 12 by turning on / off the energization of the electromagnetic clutch unit 106 of the clutch 12 and keeps the electromagnetic clutch unit 106 in an energized state while it is determined to be in the four-wheel drive state. .

Further, the 4WD controller main body 8A performs processing as shown in FIG. 6 at every predetermined sampling time.
First, in step S10, based on the drive mode switch 41, it is determined whether or not it is in the four-wheel drive mode, and if it is in the four-wheel drive mode, the process proceeds to step S20. On the other hand, in the case of transition to the two-wheel drive mode or the two-wheel drive mode, the process proceeds to step S120.

  In step S20, based on the signal from the shift position detection signal 31, it is determined whether or not the shift is in the drive range (D · R · 1 · 2), that is, a range other than parking or neutral. If it is determined that the front wheels 1L and 1R are transmitted with torque or the vehicle starts in the four-wheel drive mode at the next start, the process proceeds to step S30. Otherwise, the process proceeds to step S120 to shift to two-wheel drive. Migrate to

In step S30, it is determined whether or not the motor rotational speed is within the specification-permitted rotational speed. If it is within the allowable rotational speed range, the process proceeds to step S40. The process proceeds to S120.
In step S40, the motor torque limiter 8C is activated, and subsequently, in step S50, it is determined whether or not the motor torque is limited, that is, suppressed. If the suppression is performed, the process proceeds to step S70. If it is determined that the normal process is not performed, the process proceeds to step S60.

In step S60, the target motor torque calculation unit 8B is activated, and after obtaining the target motor torque Tm of the motor 4, the process proceeds to step S70.
Here, the target motor torque calculation unit 8B calculates the target motor torque Tm based on various conditions such as the vehicle speed and the accelerator opening. Further, when the vehicle is in a stopped state (the wheel speed is zero or substantially zero), the target motor torque Tm is not sufficient to drive the rear wheels 3L and 3R in preparation for the next start. The motor torque is set so that the play existing from the motor 4 to the rear wheels 3L and 3R can be reduced. Also, when the clutch is turned on while the vehicle is running, the motor torque is set so that the rotation speed on the clutch input side (motor rotation speed / reduction ratio) approaches the rotation speed on the clutch output side (average rotation speed of the rear left and right wheels). To do.

In step S70, the target motor field current Ifm corresponding to the rotation speed Nm of the motor 4 detected by the motor rotation speed sensor 21 is calculated, and the target motor field current Ifm is output to the motor controller 8C. The process proceeds to S75.
In step S75, using the target motor torque Tm and the target motor field current Ifm as variables, the corresponding target armature current Ia is obtained based on a map or the like, and the process proceeds to step S80. In step S80, based on the target armature current Ia, the duty ratio c1, which is a generator control command value, is calculated and output, and then the process proceeds to step S85.

  In step S85, it is determined whether or not the clutch differential rotation, that is, the difference between the clutch input side (motor drive side) rotational speed and the clutch output side (rear wheel side) rotational speed is less than a predetermined value. If the value is equal to or greater than the predetermined value, the process returns. The predetermined value here is a value such that the vehicle acceleration changes when the clutch is on and the driver does not feel a shock, and is obtained by experiment or calculation.

In step S90, a clutch-on command is output to the clutch control unit 8G, and subsequently, in step S95, “1” indicating the four-wheel drive state is substituted into the clutch state flag CLSFLG to return.
On the other hand, when it is determined that the two-wheel drive state or the transition from the four-wheel drive state to the two-wheel drive state and the process proceeds to step S120, it is determined whether or not the clutch state flag CLSFLG is “0”. Is already in the two-wheel drive state, the process is terminated without performing motor drive control. On the other hand, if the clutch state flag CLSFLG is other than “0”, the process proceeds to step S130. Here, the initial value of the clutch state flag CLSFLG is set to “0”.

In step S130, a clutch-off command is output to the clutch control unit 8G, the control state of the clutch 12 is changed to a disconnected state, and the process proceeds to step S160. When the process proceeds to step S160, the clutch state flag CLSFLG is set to “0” indicating the two-wheel drive state, and the process proceeds to step S180.
In step S180, after the process of turning off the motor, such as turning off the motor field current, is performed, the generator control command value c1 is set to zero in step S190, and then the process returns.

Next, the processing of the motor torque limiting unit 8C will be described based on FIG.
First, in step S300, the current motor torque Tma is calculated, and the process proceeds to step S310.
Although the target motor torque Tm may be used as the motor torque Tma, in consideration of a response delay such as a motor electric current, in this embodiment, the actual motor torque is calculated by the following formula to be Tma. .
Tma = Ka × Φ × Ifm × Ia
here,
Ka: Constant determined by motor specifications
Φ: Magnetic flux, a constant determined by the specifications of the motor.

The motor armature current Ia uses the previous value and is positive in the direction flowing from the generator 7 to the motor 4. The motor field current Ifm uses the previous value, and when the armature current Ia is positive, the direction in which the motor 4 outputs torque in the vehicle forward direction is positive.
In step S310, the clutch acceleration, that is, the acceleration α of the rear wheels 3L and 3R is obtained, and the process proceeds to step S320. The acceleration α may be obtained from the wheel speed difference between the rear wheels 3L and 3R per unit time (for example, sampling time).

Here, the clutch transmission torque TC is expressed by the following equation.
TC = r * Tma-sign (VWr) * Tf-Ic * [alpha] / R (1)
r: Reduction gear reduction ratio
sign (VWr): sign () is a sign function,
If VWr is a positive value, “+1” is returned, “0” is returned if VWr is zero, and “−1” is returned if VWr is a negative value.
Tf: Friction from the clutch to the motor side, a constant that can be obtained by actual measurement
Ic: Moment of inertia on the motor side of the clutch, constant obtained by actual measurement and calculation
R: Rear wheel tire radius

Therefore, when VWr> 0, that is, when the vehicle is moving forward,
TC = r × Tma−Tf−Ic × α / R (2)
When VWr <0, that is, when the vehicle is moving backward,
TC = r × Tma + Tf−Ic × α / R (3)
It is expressed.

For this reason, in the following process, it is divided into the process of step S330-S380 and the process of step S400-450 by whether the vehicle is moving forward. Note that the wheel stop state is set when the vehicle is moving backward for convenience.
That is, in step S320, it is determined whether or not the vehicle is moving forward. If it is determined that the vehicle is moving forward, the process proceeds to step S330; otherwise, the process proceeds to step S400.

In step S330, the current clutch transmission torque TC is calculated based on the above equation (2), and the process proceeds to step S340.
In step S340, it is determined whether the clutch transmission torque TC is smaller than the allowable lower limit torque TCdrg. If it is determined that the clutch transmission torque TC is smaller, the process proceeds to step S350, and if not, the process proceeds to step S360.

The allowable lower limit torque TCdrg is a value that is assumed that the clutch transmission torque TC does not become a negative value due to an undershoot due to a control delay of the motor torque.
In step S350, based on the following equation, the target motor torque Tm is set to the motor torque at which the clutch transmission torque TC becomes the allowable lower limit torque TCdrg, and the process proceeds to step S380. Since the clutch transmission torque TC only needs to be equal to or greater than the allowable lower limit torque TCdrg, the motor torque value may be calculated to be larger than the value obtained by the following equation.
Tm = (TCdgr + Tf + Ic × α / R) / r

In step S380, “1” is assigned to the motor torque limit flag TmFLG, and the process ends.
On the other hand, in step S360, it is determined whether or not the clutch transmission torque TC is larger than the allowable upper limit torque TCdmg. If it is determined that the clutch transmission torque TC is larger, the process proceeds to step S370. .
The allowable upper limit torque TCdmg is a value that has a margin (small) by the control margin of the motor torque with respect to the limit torque of the clutch transmission torque TC, which is determined by the specifications of the clutch 12, and is an overshoot due to a control delay of the motor torque. It is a value that does not exceed the limit torque.

In step S370, based on the following formula, the target motor torque Tm is set to the motor torque at which the clutch transmission torque TC becomes the allowable upper limit torque TCdmg, and the process proceeds to step S380. Since the clutch transmission torque TC only needs to be equal to or less than the allowable lower limit torque TCdmg, the clutch transmission torque TC may be calculated to be a motor torque value smaller than a value obtained by the following equation.
Tm = (TCdmg + Tf + Ic × α / R) / r

In step S390, “0” is substituted for the motor torque limit flag TmFLG, and the process ends.
On the other hand, when it is determined in step S320 that the vehicle is traveling backward and the process proceeds to step S400, the current clutch transmission torque TC is calculated based on the above equation (3), and the process proceeds to step S410.
In step S410, it is determined whether or not the clutch transmission torque TC is greater than the allowable lower limit torque −TCdrg on the negative side (small in absolute value). If it is determined that the clutch transmission torque TC is larger, the process proceeds to step S420. Proceeds to step S430.

In step S420, based on the following formula, the target motor torque Tm is set to the motor torque at which the clutch transmission torque TC becomes the above-described allowable lower limit torque TCdrg, and the process proceeds to step S450. Since the clutch transmission torque TC only needs to be equal to or less than the allowable lower limit torque TCdrg, it may be calculated so that the motor torque value is smaller than the value obtained by the following equation.
Tm = (− TCdgr−Tf + Ic × α / R) / r
In step S450, “1” is assigned to the motor torque limit flag TmFLG, and the process ends.

On the other hand, in step S430, it is determined whether or not the clutch transmission torque TC is smaller than the negative allowable upper limit torque −TCdmg. If it is determined that the clutch transmission torque TC is smaller, the process proceeds to step S440. The process proceeds to S390.
In step S440, based on the following equation, the target motor torque Tm is set to a motor torque at which the clutch transmission torque TC becomes the allowable upper limit torque −TCdmg on the negative side, and the process proceeds to step S450. Since the clutch transmission torque TC only needs to be equal to or greater than the allowable lower limit torque TCdmg, the motor torque value may be calculated to be larger than the value obtained by the following equation.
Tm = (− TCdmg−Tf + Ic × α / R) / r

In step S390, “0” is substituted for the motor torque limit flag TmFLG, and the process ends.
Here, steps S340 and S410 constitute clutch torque state determination means, and steps S350 and S420 constitute motor torque suppression means.
The engine controller 18 calculates a control amount (throttle opening, etc.) based on the accelerator opening, the vehicle speed, etc., and controls the engine to the target output torque. Further, even if the vehicle is in a stopped state, if the duty ratio c1 that is the generator control command value is larger than zero, the engine 2 is operated by calculating a control amount that can output torque enough to operate the generator 7. Make it work.

Next, the operation of the apparatus having the above configuration will be described.
When the driver selects the four-wheel drive mode or automatically determines that the four-wheel drive conditions are met, the motor torque is set according to the vehicle speed, accelerator opening, acceleration slip amount of the front wheels 1L, 1R, etc. When 4 is driven, a four-wheel drive state is achieved and the acceleration of the vehicle is improved.
Further, when the drive mode switch 41 is switched to the two-wheel drive mode from the four-wheel drive state, the clutch 12 is controlled to be disconnected and the motor 4 is stopped as the transition process to the two-wheel drive state. .

  Here, the operation of the clutch 12 employed in the present embodiment will be described. When the electromagnetic clutch portion 106 is energized, the circumferential position of each roller 102 is restrained (fixed) to the outer ring via the cage 104. It becomes a state. When the driving torque from the motor 4 is transmitted to the outer ring member 101 in this state, a phase difference is generated between the outer ring member 101 and the roller 102 and the inner ring member 100, and relatively in the central portion of the engagement space 103. Each of the rollers 102 that have been positioned engages with the left wedge space 103a, so that torque can be transmitted from the outer ring member 101 to the inner ring member 100 via the roller 102, as shown in FIG. As a result, the rear wheels 3L and 3R, which are driven wheels, are driven by the torque of the motor 4.

  Further, when the energization of the electromagnetic clutch unit 106 is stopped in the torque transmission state from the motor 4, that is, when the cage 104 is released with the clutch control current turned off, the torque transmission torque from the motor 4 is normally gradually reduced. When the spring force of the switch spring 105 wins, the roller 102 returns to the center position of the engagement space 103, and the clutch 12 is actually disengaged.

  Therefore, when the clutch 12 having the above-described mechanism is employed, the actual disconnection of the clutch 12 is not performed even if the clutch 12 is controlled to be turned off (the energization of the electromagnetic clutch unit 106 is stopped) while the motor torque is large during normal traveling. As a result of always being executed when the motor torque is small (when the acceleration α on the motor 4 side and the acceleration α on the wheel side at the clutch position approach the same value), the shock generated when the actual clutch 12 is disengaged In addition, the clutch 12 can be easily turned off. The clutch 12 is inexpensive.

  Here, if the rear wheel is suddenly braked by a sudden brake or the like while driving in the four-wheel drive state, that is, the state where the clutch 12 is connected and the rear wheel is driven by the motor 4, the above-described (1) to (1) to As can be seen from the equation (3), the clutch transmission torque TC acting on the clutch 12 is a combination of the torque from the motor side and the torque from the rear wheel side, so that the clutch transmission torque TC approaches the limit torque, that is, with respect to the clutch life. There is a risk that the torque will be greatly affected. On the other hand, in the present embodiment, when the clutch transmission torque TC exceeds the upper limit allowable torque TCdmg before the excessive torque is reached, the target motor torque Tm is reduced to the motor torque that can suppress the clutch transmission torque TC to the upper limit allowable torque TCdmg. By limiting the clutch torque, the clutch transmission torque TC is prevented from exceeding the limit torque, and the life of the clutch 12 is prevented from decreasing.

If the allowable torque TCdmg is exceeded only by the torque transmitted from the rear wheel to the clutch 12 by braking, the target motor torque Tm is limited to a negative value. Since the target motor torque Tm becomes a negative value in this way, the braking force applied to the rear wheel can be set to be large accordingly.
On the other hand, when the electromagnetic clutch unit 106 is energized, that is, when traveling with clutch control on, for example, assuming a traveling state such as traveling on a steep downhill, the wheel speeds of the rear wheels 3L and 3R are large. Thus, when the acceleration of the inner ring member 100 becomes larger than that of the outer ring member 101, that is, when the torque from the wheel side exceeds the torque from the motor 4 side, the outer ring member 101, the roller 102, and the inner ring member 100 As a result of the elimination of the phase difference between them and the occurrence of a phase difference in the opposite direction, the roller 102 is disengaged, and the right wedge space 103a located on the opposite side as shown in FIG. The roller 102 bites. That is, a so-called reverse biting state is established, and the torque is transmitted from the rear wheel side toward the motor 4 side. In this state, when the energization of the electromagnetic clutch unit 106 is stopped and the cage 104 is released, normally, unless the torque of the motor 4 is increased (or the torque from the wheels is not decreased), the reverse biting is performed. The congested state does not disappear.

  On the other hand, in the present embodiment, when the clutch transmission torque TC becomes so small that the clutch transmission torque TC becomes a dragging direction torque (a negative value during forward traveling), that is, when the clutch transmission torque TC becomes smaller than the lower limit allowable torque TCdrg, In steps S320 and S330 (steps S410 and S420 at the time of reverse), the absolute value of the clutch transmission torque TC is limited to the lower limit allowable torque TCdrg or more to prevent the reverse engagement.

The above description is made on the assumption that the vehicle is traveling forward. However, the same operation and effect can be obtained even when the vehicle is moving backward.
Here, in the above embodiment, when the clutch transmission torque TC exceeds the upper limit allowable torque and approaches the limit torque, the motor torque is limited so that the clutch transmission torque TC becomes the upper limit allowable torque. Instead of applying a limit, the motor 4 is turned off, or a clutch that can be turned off even when the transmission torque TC is applied, such as a friction clutch, is used, and the clutch 12 is controlled to be disconnected, so that the clutch 12 is engaged. The clutch transmission torque TC may be prevented from becoming an excessive torque that is greater than or equal to the limit torque.

  In the above embodiment, the torque transmitted from the rear wheel to the clutch 12 is obtained from the acceleration α of the rear wheel to determine whether or not the clutch transmission torque TC has approached the limit torque. However, the present invention is not limited to this. The torque transmitted from the rear wheel side to the clutch 12 may be calculated by predicting the braking operation amount, that is, the depression amount of the brake pedal, or the deceleration of the rear wheel from the master cylinder pressure. In this case, it is possible to determine whether or not the clutch transmission torque TC has approached the limit torque by feedforward. Further, whether or not the clutch transmission torque TC approaches the limit torque may be determined from both the calculation from the actual rear wheel acceleration α and the estimated value based on the braking operation amount. Alternatively, when an automatic braking device such as an ABS device is operating, it is determined that the clutch transmission torque TC has approached the limit torque unconditionally, and the motor torque is reduced by half, or the motor is turned off. Or you can do it.

  Moreover, although the said embodiment demonstrated in the case of the structure which drives the motor 4 with the voltage which the generator 7 generated, and implements four-wheel drive, it is not limited to this. You may employ | adopt for a drive system provided with the battery which can supply electric power to the motor 4. FIG. In this case, power may be supplied from the battery, and power supply from the generator 7 may be performed concurrently with the supply from the battery.

Moreover, in the said embodiment, although the internal combustion engine was illustrated as a main drive source, you may comprise a main drive source from a motor etc. In the above embodiment, a four-wheeled vehicle is described as an example. However, the present invention may be applied to a two-wheeled vehicle using a motor as a drive source.
Further, in the description of the clutch 12, the engagement space 103 is formed in a portion where the inner ring member 100 and the outer ring member 101 are opposed to each other in the radial direction. 103 may be formed. Further, the cam surface 100a may be provided on the outer ring member 101 side, and the inner ring member 100 and the cage 104 may be fixed and released by the clutch operating portion. Further, a clutch mechanism other than the electromagnetic clutch may be employed as the clutch operation unit.

The clutch 12 is not limited to the clutch as described above, and may be a dog clutch or a friction clutch. The mechanical clutch as described above has a larger transmission torque capacity and is easier to cost than a friction clutch. However, when an excessive torque is applied, the torque life is greatly reduced compared to the friction clutch.
Next, a second embodiment will be described with reference to the drawings. The same devices as those in the first embodiment will be described with the same reference numerals.

The basic configuration of the second embodiment is the same as that of the first embodiment, but part of the processing of the 4WD controller main body 8A is different, and the processing of the clutch protection check unit 8H is incorporated instead of the motor torque limiting unit 8B. Is different.
That is, in the 4WD controller main body of the present embodiment, as shown in FIG. 10, the processes of steps S33 and S34 are inserted between steps S30 and S60, and the processes of steps S40 and S50 in FIG. 6 are deleted. is there. Other configurations and processes are the same as those in the first embodiment.

  That is, before performing normal motor torque control (steps S60 to S80), in step S33, the clutch protection check unit 8H is activated to estimate the state of the clutch transmission torque TC, and then the process proceeds to step S34. If it is determined that CP = 1, that is, the clutch transmission torque TC may exceed the limit torque, the process proceeds to step S120, transitions to the two-wheel drive state, the motor 4 is turned off, and CP is 0, that is, clutch transmission. When it is determined that there is no possibility that the torque TC exceeds the limit torque, the process proceeds to step S60, and normal four-wheel drive processing is performed.

Next, the processing of the clutch protection check unit 8H will be described with reference to FIGS.
In the present embodiment, as shown in FIG. 12, the region (the hatched portion in FIG. 12) where the clutch transmission torque TC may exceed the limit torque in advance is calculated through experiments and calculations using the driven wheel speed and the motor torque as variables. I will ask for it.
In step S600 in FIG. 11, the wheel speed VR of the driven wheel (rear wheel) is detected. Subsequently, in step S610, the motor torque Tma is obtained, and the process proceeds to step S620. As the motor torque Tma, the actual motor torque may be calculated as described above, or the target motor torque Tm may be used.

In step S630, it is determined whether or not a braking operation has been performed. If it is determined that the braking operation has been performed, the process proceeds to step S640. If the braking operation has not been performed, the process proceeds to step S650 to protect the clutch. “0” is assigned to the area flag CP, and the process is terminated.
The braking operation may be determined by the operation amount of the brake pedal. It is also determined that the brake operation has been performed when the parking brake is operated.
In step S640, based on the map as shown in FIG. 12 or the like, it is determined whether or not the relationship between the current motor torque and the driven wheel speed is a protection area (shaded area). If 1 is determined to be an unprotected area, 0 is assigned to CP and the process is terminated.

Here, steps S630 and S640 constitute clutch torque state determination means, and step S34 constitutes motor torque limiting means.
Next, functions and effects of this embodiment will be described.
Usually, a large sudden deceleration is applied to the rear wheel when the rear wheel is braked. Therefore, in this embodiment, when a braking operation is performed, the motor torque obtained in advance and the wheel speed of the driven wheel are From the relationship, when it is determined that the clutch transmission torque TC may exceed the limit torque, the clutch is disconnected to protect the clutch.

Other configurations and operational effects are the same as those in the first embodiment.
Here, in the above embodiment, when it is determined that the clutch transmission torque TC may exceed the limit torque, the clutch is set to the disconnected state and the motor is controlled to the disconnected state. However, the clutch is only controlled to the disconnected state. Thus, it is not necessary to turn off the motor (transition to the two-wheel drive state). That is, if it is determined in step S34 of the 4WD controller main body (FIG. 10) that CP = 1, a clutch-off command may be output to end the process.
In the above embodiment, the above-described processing is performed when a braking operation by the driver is detected. However, when an automatic braking device such as an ABS device is activated, the process proceeds to step S630 in the clutch protection check unit 8H (FIG. 11). Then, the process may proceed to step S640.

It is a schematic device block diagram concerning the embodiment based on the present invention. It is a system configuration figure concerning an embodiment based on the present invention. It is sectional drawing which shows the structure of the clutch which concerns on this embodiment. It is a schematic diagram which shows the mechanism of the clutch which concerns on this embodiment. It is a block diagram which shows the 4WD controller which concerns on 1st Embodiment based on this invention. It is a figure which shows the process of the 4WD controller main body which concerns on this embodiment. It is a figure which shows the process of the motor torque limiting part which concerns on 1st Embodiment based on this invention. It is a figure which shows the state which has torque transmission from a motor to a wheel. It is a figure which shows the state which has torque transmission from a wheel to a motor. It is a figure which shows the process of the 4WD controller main body which concerns on this embodiment. It is a figure which shows the process of the clutch protection check part which concerns on 2nd Embodiment based on this invention. It is a figure which shows the example of the protection area which concerns on 2nd Embodiment based on this invention.

Explanation of symbols

1L, 1R Front wheel 2 Engine 3L, 3R Rear wheel 4 Motor 6 Belt 7 Generator 8 4WD controller 8A 4WD controller body 8B Target motor torque calculator 8C Torque calculator before stop 8D Generator controller 8E Relay controller 8F Motor controller 8G Clutch control unit 8H Clutch protection check unit 9 Electric wire 10 Junction box 11 Reducer 12 Clutch 14 Intake pipe 15 Main throttle valve 16 Sub throttle valve 18 Engine controller 19 Step motor 20 Motor controller 21 Engine speed sensor 22 Voltage regulator 23 Current sensor 26 Motor rotation speed sensor 27FL, 27FR, 27RL, 27RR
Wheel speed sensor 30 Transmission 31 Differential gear 32 Shift position detecting means 34 Brake pedal 35 Brake stroke sensor 36 Brake controller 37FL, 37FR, 37RL, 37RR
Braking device 40 Accelerator sensor 41 Drive mode switch 42 ABS device (automatic deceleration device)
100 Inner ring member 101 Outer ring member 102 Roller (engagement element)
103 engagement space 103a wedge space 104 cage 105 switch spring 106 electromagnetic clutch portion Ifh generator field current V generator voltage Nh generator speed Ia target armature current Ifm target motor field current E induction of motor Voltage Nm Motor rotation speed (rotation speed)
Th Target generator load torque Tm Current target torque Tma Current motor torque Te Engine output torque α Rear wheel acceleration TC Clutch transmission torque TCdmg Upper limit allowable torque TCdrg Lower limit allowable torque

Claims (8)

A vehicle driving force control device includes a motor, wheels driven by the motor, and a clutch interposed in a power transmission path from the motor to the wheels, and controls the clutch to a connected state during motor driving. And
Clutch torque state determining means for detecting or estimating that the transmission torque of the clutch has approached a limit torque based on the specifications of the clutch;
Motor torque limiting means for limiting the driving torque of the motor when it is determined that the transmission torque of the clutch has approached the limit torque based on detection or estimation of the clutch torque state determination means ,
When it is determined that the torque transmitted from the wheel to the clutch approaches the limit torque, and the clutch transmission torque approaches the limit torque, the motor torque limiting means sets the drive torque of the motor as a torque in the reverse rotation direction. A driving force control device for a vehicle. A vehicle driving force control device includes a motor, wheels driven by the motor, and a clutch interposed in a power transmission path from the motor to the wheels, and controls the clutch to a connected state during motor driving. And
Clutch torque state determining means for detecting or estimating that the transmission torque of the clutch has approached a limit torque based on the specifications of the clutch;
Motor torque limiting means for limiting the driving torque of the motor when it is determined that the transmission torque of the clutch has approached the limit torque based on detection or estimation of the clutch torque state determination means,
The clutch torque state determination means obtains the clutch transmission torque from the wheel deceleration and the motor torque, and detects or estimates that the clutch transmission torque has approached the limit torque. Control device. A vehicle driving force control device includes a motor, wheels driven by the motor, and a clutch interposed in a power transmission path from the motor to the wheels, and controls the clutch to a connected state during motor driving. And
Clutch torque state determining means for detecting or estimating that the transmission torque of the clutch has approached a limit torque based on the specifications of the clutch;
Motor torque limiting means for limiting the drive torque of the motor when it is determined that the clutch transmission torque has approached the limit torque based on detection or estimation of the clutch torque state determination means, and a braking device for braking the wheel. ,
When the clutch torque state determining means determines that the braking command is output to the braking device and the speed of the wheel relative to the motor torque is a speed at which the clutch transmission torque may approach the limit torque, It is estimated that the transmission torque of the vehicle approaches the limit torque. A motor, a wheel driven by the motor, and a clutch interposed in a power transmission path from the motor to the wheel, and controlling the clutch to a connected state while the motor is driven; Is a driving force control device for a vehicle including an automatic braking device that applies a braking force to the vehicle regardless of the running state of the vehicle,
Clutch torque state determining means for detecting or estimating that the transmission torque of the clutch has approached a limit torque based on the specifications of the clutch;
Motor torque limiting means for limiting the driving torque of the motor when it is determined that the transmission torque of the clutch has approached the limit torque based on detection or estimation of the clutch torque state determination means,
When the clutch torque state determining means detects that the automatic braking device is operating, the clutch torque state determining means estimates that the clutch transmission torque has approached a limit torque based on the specifications of the clutch. apparatus. 3. The vehicle driving force control according to claim 2 , further comprising: a braking device that brakes the wheel, wherein the clutch torque state determination means estimates a deceleration of the wheel based on a braking command to the braking device. apparatus. When the motor torque limiting means determines that the clutch transmission torque has approached the limit torque, the motor torque limiting means may set the clutch in a disconnected state together with the motor driving torque limitation or instead of limiting the motor driving torque. The vehicle driving force control apparatus according to any one of claims 2 to 4, wherein the driving force control apparatus for a vehicle is characterized by the following.   The vehicle driving force according to any one of claims 1 to 6, further comprising a main driving source for driving the main driving wheel, and the wheel driven by the motor as a driven wheel. Control device. The clutch includes a first rotating member that is connected to the rotating shaft on the motor side, a second rotating member that is connected to the rotating shaft on the wheel side, and an engagement formed between the first and second rotating members. An engagement member inserted in the joint space, a retainer that regulates the circumferential position of the engagement member, and the engagement of the clutch by fixing and releasing the retainer with respect to one of the first and second rotating members. A clutch operating unit that controls disengagement, and the phase between the other of the first and second rotating members and the cage changes when the cage is fixed by the clutch operating unit. 8. The clutch according to claim 1, wherein the coupling is a clutch of a mechanism that is engaged between the first and second rotating members so that torque can be transmitted between the first and second rotating members. The vehicle driving force control apparatus according to claim 1.

Images