JP3393665B2 - Vehicle drive system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a vehicle which is driven by using a motor in addition to an engine. 2. Description of the Related Art In recent vehicles, four-wheel drive vehicles tend to increase, but one of right and left front wheels and right and left rear wheels is driven by an engine to reduce weight and the like. In some cases, the main drive wheel is used, and the other wheel is used as an auxiliary drive wheel driven by a motor. Japanese Patent Application Laid-Open No. 2-120136 discloses two different driving forces.
There has been proposed a motor that uses one motor to change the type and number of motors to be operated in accordance with the gear position of the transmission, that is, a motor that changes the auxiliary driving force of the motor. Japanese Patent Laying-Open No. 57-74222 discloses that the distribution of hydraulic pressure to two right and left hydraulic motors (hydraulic cylinders) is automatically performed according to the road load applied to the left and right auxiliary drive wheels. In addition, a device having a function of a differential device has been proposed. Japanese Unexamined Patent Publication (Kokai) No. 63-38031 discloses the use of two electric motors on the left and right sides. The higher the vehicle speed, the larger the generated voltage and the constant the generated torque of the motor. With the manual switch,
There has been proposed an apparatus which can switch between driving execution and driving stop by a motor. [0005] Incidentally, the driving of the auxiliary driving wheels using the motor is merely auxiliary, and furthermore, the state of the four-wheel drive for driving the motor and the motor.
Since there is a difference in vehicle characteristics from a two-wheel drive state in which the motor is not driven, the drive assist by the motor should be in a limited area where it is strongly desired to effectively transmit the driving force to the road surface. What is desired. In addition to this,
Since the driving energy of the motor ultimately depends on the engine, it is desirable to minimize the auxiliary driving by the motor from the viewpoint of improving fuel efficiency. SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle drive device in which the setting of a region for driving an auxiliary drive wheel by a motor can be more appropriately set. To achieve the above object, the present invention has the following configuration. That is, as described in claim 1 of the claims, one of the left and right front wheels and the left and right rear wheels is a main drive wheel driven by an engine via a transmission and a differential device. In a vehicle in which the other wheel is an auxiliary drive wheel driven by a motor, the motor is provided as a pair of left and right wheels so that the left and right auxiliary drive wheels can be driven independently of each other. Motor control means for causing the motor to generate a positive driving force, which is a driving force in the same direction as the traveling direction of the vehicle, provided that the vehicle is traveling straight and accelerating;
The motor control means integrally controls the left and right motors under common driving conditions so that the left and right auxiliary drive wheels have the same rotational speed when the vehicle is slowly accelerated, and when the vehicle is rapidly accelerated. The motors are set so as to be independently controlled under independent driving conditions so that the target rotational speeds are set independently on the left and right sides. According to the present invention, basically, it is assumed that the vehicle is stable and that the driving force is required to be effectively transmitted to the road surface, such as during straight-ahead acceleration. Since a positive driving force is generated to assist the vehicle in traveling by the motor, good acceleration can be obtained while ensuring the stability of the vehicle. In particular, it is possible to obtain a sufficient acceleration performance by effectively transmitting the driving force to the road surface at the time of rapid acceleration, while preventing a large disturbance of the vehicle attitude at the time of gentle acceleration, that is, securing the straight running stability. be able to. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hydraulic system, etc. (FIG. 1) In FIG. 1, 1FL is a front left wheel, 1FR is a front right wheel, 1R
L is a left rear wheel, and 1RR is a right rear wheel. An engine 2 is disposed in front of the vehicle body, and a driving force of the engine 2, that is, a generated torque is transmitted to a differential device 5 via a clutch 3, a manual transmission 4 having five forward speeds and one reverse speed. Then, the left front wheel 1FL is output from the differential device 5 via the left drive shaft 6L.
The engine driving force is transmitted to the right front wheel 1FR via the right drive shaft 6R. The left and right front wheels 1FL and 1FR to be steered are linked by a steering link 7 such as a tie rod, and the steering link 7 and the handle 8 are linked via a rack and pinion mechanism 9. The left and right rear wheels 1RL, 1RR are
Separately and independently, a pair of left and right hydraulic motors ML, MR
It is adapted to be driven by. That is, the left rear wheel 1RL is connected to the left motor M via the left drive shaft 11L.
L, and the right rear wheel 1RR is driven by the right drive shaft 11
Driven by the right motor MR via R. This motor ML, that is, the left drive shaft 11L
And the motor MR, that is, the right drive shaft 11R, are separated from each other so that the left and right can be driven independently. The left and right drive shafts 11L and 11R are
The hydraulic clutch 12 is capable of intermittent operation. The motor ML (MR) is of a turbine type (impeller type) and has a first connection port La (Ra) and a second connection port Lb (Rb), and La (Ra). ) To Lb (Rb)
When the high-pressure oil liquid flows to the
When the high-pressure oil liquid flows in a direction opposite to this, the rotation is made in the backward direction. The motors ML and MR have the same specifications, and the total value of the maximum generated torque is about 1/3 to 1/2 of the maximum generated torque of the engine 2. In the embodiment, the rear wheel drive by the motors ML and MR is executed only under predetermined conditions described later. That is, the left and right front wheels 1FL,
Even when 1FR is driven, the left and right rear wheels 1RL, 1RL
RR may not be driven by the motors ML and MR. P is a pump as a hydraulic pressure generating source. The pump P is of a variable displacement type, and has an output shaft 2 of the engine 2.
The drive pulley 13, the belt 14, and the driven pulley 15 drive the drive pulley 13a. The high-pressure oil pumped by the pump P from the reservoir tank 16 is discharged to a high-pressure line 18 to which a check valve 17 is connected. From this high-pressure line 18, first and second hydraulic pressure supply lines 31A and 31B connected to the check valve 10 or 32 are connected in parallel. Further, a release line 23 extends from the reservoir tank 16.
Furthermore, each connection port La, Lb (R) of the motor ML (MR)
a, Rb), the parallel lines 20L, 21L
(20R, 21R) are derived. Lines 20L and 21L of the left motor ML are provided with a switching valve VVA, mutually parallel lines 19 and 19L and lines 22 and 22L, and switching valves VVB · L and VVE ·.
L, the first supply line 31A and the release line 23
Can be selectively connected to. Similarly, lines 20R and 21R of the right motor MR are connected to the switching valves VVA,
Lines 19, 19R and lines 22, 22 parallel to each other
R, and switching valves VVB • R, VVE • R,
The first supply line 31A and the release line 23 can be selectively connected. A switching valve VVI is connected to the second common supply line 31B on the downstream side of the check valve 32, and a flow dividing valve 34 is connected on the downstream side. One branch supply line 33L branched into two by the branch valve VVI is connected to the line 19L, and the other branch supply line 33R is connected to the line 19R. An accumulator 41 for storing high-pressure oil pressure is connected to the high-pressure line 18. For this high pressure line 18, a line 20L (20R)
Are connected by a passage 42L (42R). This passage 42L (42R) has a check valve 43L (43
R) and the switching valve VVF · L (VVF · R) are connected. The passages 43L and 43R are parallel to each other, and each of the valves VVA, VVB · L (VVB · R), VVE · L (V
VE · R), VVI, the flow dividing valve 34 and the like are bypassed. The line 20L (20R) and the line 21
L (21R) is communicated with a communication path 51L (51R), and a variable orifice VVC · L (VVC · R) is connected to the communication path 51L (51R). An actuator for connecting and disconnecting the clutch 12 is indicated by reference numeral 61. This actuator 61
Supply line 62 for high pressure line 18 and discharge line 63 for release line 23, switching valve VVJ
And the two lines 62 and 63 can be shut off by the switching valve VVJ. The left and right motors ML and MR are connected to each other by a communication passage 71.
VD is connected. The release line 23 is connected to the high pressure line 18 on the upstream side (pump P side) of the check valve 17 via a load / unload valve VVH and on the downstream side of the check valve 17. Are connected via a safety valve VVG. Description of Control Modes (Table 1) This embodiment has a total of eight types of control modes, as will be described later, and controls each of the above-described valves when each mode is executed. The operating conditions are summarized in Table 1 below. In this table, symbols “L” and “R” for identifying left and right are omitted. The load / unload valve VVH not shown in Table 1 is controlled to open and close so that the pressure in the high pressure line 18 falls within a predetermined pressure range between a lower limit and an upper limit. [Table 1] In each control mode shown in Table 1, the operating state of the valve which performs the main function will be specifically described.
It is as follows. (1) Integrated mode In the integrated mode, the drive control of the motors ML and MR is performed so that the left and right rear wheels 1RL and 1RR have the same rotational speed, as will be described in detail later. There are two types, drive (drive assist) and reverse drive (braking). In this integration mode,
The clutch 12 is engaged (the switching valve VVJ opens the line 62 and closes the line 63), and the switching valve VVB · L (V
VB · R), VVE · L (VVE · R) and VVI are in the state shown in FIG. In this state, the switching valve VVA is controlled to switch the hydraulic pressure supply direction according to the forward drive or the reverse drive (setting the forward and reverse directions of the motors ML and MR) and to control the motors ML and MR. The supply flow rate is controlled (hydraulic supply using the first supply line 31A).
In the reverse drive, a larger deceleration is obtained than in the hydraulic lock mode described later. However, it is natural that the rear wheels 1RL and 1RR rotate in a direction opposite to the traveling direction of the vehicle. It does not provide any driving force. (2) Independent mode The independent mode is such that the motor ML is such that the left and right rear wheels 1RL and 1RR have the target rotational speeds set independently of each other, as will be described in detail later. , MR drive control, and there are two types of forward drive and reverse drive as in the case of the integrated mode. In this independent mode, the clutch 12 is released (the switching valve VVJ closes the line 62 and opens the line 63). Switching valve VVE-L (VVE-R)
Is operated as shown in FIG. 1, but the switching valve VVA
Is set to the center switching position and the first supply line 31A is shut off. The switching valve VVI is set to the open position, and the hydraulic pressure is supplied using the second supply line 31B. In this state,
By controlling the switching valve VVB · L (VVB · R), switching of the hydraulic pressure supply direction according to forward drive or reverse drive (motor M
L, MR forward and reverse directions) and motors ML, M
The supply flow rate for R is controlled. (3) LSD Mode In the LSD mode, a differential limiting function is obtained on the premise that the vehicle turns, and the switching valves VVB · L and VVB · R are connected to the lines 20L, 21L (20R, 21R). ) Are closed to completely shut off the supply and discharge of hydraulic pressure to the motors ML and MR. Then, the on-off valve VVD is opened,
The closed left and right hydraulic paths of both motors ML and MR communicate with each other to prevent a large rotation difference between left and right motors ML and MR. This LSD mode
In this mode, the variable orifice VVC · L (VVC · R) is fully closed. Since the LSD mode has no direct relation to the present invention, further detailed description will be omitted. (4) Hydraulic Lock Mode In the hydraulic lock mode, the passage resistance, that is, the variable orifice VVC · L (VV
(C · R) to obtain a deceleration force using the throttle resistance. In this hydraulic lock mode, the switching valves VVB · L, V
When VB / R is in the center switching position, lines 20L, 21
L, 20R, and 21R are shut off, and the on-off valve VVD is closed. And the variable orifices VVC · L, V
VC-R is opened. In this state, the oil liquid
Variable orifice VVC · L according to rotation of L (MR)
(VVC · R), the closed orifice circuit is closed. The orifice resistance of the variable orifice VVC · L (VVC · R) through which the oil liquid passes during circulation is limited by the vehicle. Will give a deceleration force to the vehicle. Then, the opening degrees of the variable orifices VVC · L and VVC · R are controlled to decrease as the deceleration of the vehicle increases. Note that the clutch 12 may be in either the engaged state or the released state. (5) Accumulation mode In the accumulation mode, the vehicle, that is, the rear wheels 1RL, 1R
The motors ML and MR driven by R function as pumps to accumulate pressure in the accumulator 41. In this pressure accumulation mode, the line 21L (21R) communicates with the reservoir tank 16 while the on-off valve VVF · L
When (VVF.R) is opened, the oil liquid in the reservoir tank 16 is pumped up by the motor ML (MR) and accumulated in the accumulator 41. This pressure accumulation mode is preferably executed at the time of deceleration of the vehicle, but may be executed at the time of high-speed steady running. (6) Stop mode The stop mode is a mode in which the motors ML and MR stop the vehicle when the parking brake is not operating.
(The driving of the motors ML and MR is controlled so that the vehicle speed becomes the target vehicle speed 0). In this case, the hydraulic pressure supply line uses the second supply line 31B, and the supply / discharge control of the hydraulic pressure is performed by the switching valve VVB · L (VVB · L).
R). (7) Parking Mode The parking mode enhances the action of maintaining the parking state when the parking brake is activated. That is, in the parking mode, the switching valve VVB · L
(VVB · R) is set to the closed position of the center switching position, the hydraulic supply / discharge line is cut off, and the clutch 12 is engaged. (8) F / S mode The F / S mode is a fail-safe mode. When there is any abnormality, for example, when the high-pressure line becomes abnormally high, the mode is changed. -When the valves ML and MR are not driven normally, when a certain valve is stuck, or when the oil temperature becomes higher than a predetermined temperature, and the like, the safety valve VVG is opened, The oil pressure in the high pressure line 18 is released. Description of Control System (FIG. 2) FIG. 2 shows a control system in the present invention. In the figure, U1, U2 and U3 are control units each constructed using a microcomputer.
Is a main control unit that controls the above-described valves VVA and the like. The control unit U2 is for ABS control (anti-lock brake control), and the control unit U3
Is for traction control. Also, S1 to S12 are:
Each is a sensor or a switch. The sensors S1 to S4 are provided for each wheel 1FL to 1R.
The rotation speed of R, that is, the wheel speed is detected independently, and the wheel speed detected by each of the sensors S1 to S4 is transmitted from the control unit U2 to the control units U1 and U3. The sensor S5 detects the vehicle speed. In the embodiment, the sensor S5 detects the ground vehicle speed (detection of the absolute vehicle speed). The sensor S6 detects a shift position of the transmission 4, that is, a gear position. The sensor S7 detects the engine speed. The sensor S8 detects the steering angle of the steering wheel. The sensor S9 detects the accelerator opening. The sensor S10 detects the depression amount of the brake pedal. The switch S11 is an ignition switch. The switch S12 detects whether the parking brake has been activated. The signals from the sensors or the switches S5 to S12 are input to the control unit U1, and the control unit U1 controls the above-described valves VVA to VVJ. Of course, the control unit U2 is for preventing the wheels from locking during braking, and the control unit U2 provides a brake hydraulic pressure for independently adjusting the braking of each wheel. The adjusting unit 81 is controlled. Further, the control unit U3 includes left and right front wheels 1F which are always driven when acceleration or the like.
When the slip on the road surface of L, 1FR becomes excessive, at least the engine output (torque generated by the engine 2) is reduced. For example, the opening degree of the throttle valve of the engine 2, the ignition timing, the fuel injection amount, etc. The adjusting torque adjusting means 82 is controlled. From the control unit U2 to the control unit U1, in addition to the wheel speed signals detected by the sensors S1 to S4, A
An ABS signal indicating that the BS control is being executed and a μ signal indicating the road μ (friction coefficient) are transmitted. Further, a wheel speed signal is transmitted from the control unit U2 to the control unit U3. Further, the control unit U3 sends to the control unit U1 a T indicating that the traction control is being executed.
In addition to the RC signal, a torque reduction signal indicating the amount of reduction in engine torque performed by the traction control and a road surface μ signal are transmitted. The detection of the road surface μ can also be performed by the control unit U1, and the sensors S1 to S1
Each wheel speed detected in S4 may be directly input to the control unit U1. Explanation of the flowchart (FIG. 3) Next, the control contents of the control unit U1 will be described with reference to the flowchart of FIG. 3, but FIG. Only the running state of a certain integrated mode, the positive drive in the independent mode and the LSD mode are shown, and the other control modes are not directly related to the present invention. Omitted. In the following description, E, Z
Indicates a step. After the signals from the sensors and the like are read in E1 in FIG. 3, it is determined in E2 whether the vehicle speed is higher than a predetermined vehicle speed. If the determination in E2 is NO, it is determined in E3 whether the vehicle is traveling straight. If the determination in E3 is YES,
At E4, it is determined whether or not the vehicle is accelerating. If the determination in E4 is YES, it is determined in E5 whether rapid acceleration is being performed. If the determination in E5 is YES, in E6, the normal driving is executed in the independent mode, that is, the motor driving force is generated in the direction to assist the vehicle traveling. When the determination in E5 is NO, that is, at the time of slow acceleration, the normal drive in the integrated mode is executed in E7. The degree of acceleration can be detected by various known techniques. For example, the degree of acceleration can be known from any one of the magnitude of the accelerator pedal depression speed, the amount of increase in the accelerator pedal depression amount, the vehicle body acceleration obtained by differentiating the vehicle speed, or any combination of a plurality of these. If the determination in E2 is YES,
At E8, the normal drive execution is prohibited. If the determination in E4 is NO, the control is returned to E1 as it is,
At this time, the execution of the forward drive is not performed. When the determination in E3 is NO, that is, when the vehicle is turning, it is determined in E9 whether the lateral G (lateral acceleration) acting on the vehicle body is a predetermined high G or more. If the determination in E9 is NO, the control is returned as it is. If the determination in E9 is YES, the LSD mode is executed in E10. Description of the flowchart (FIG. 4) FIG. 4 shows details of the positive drive control in the independent mode. The positive drive control in the integrated mode differs from the positive drive control in the independent mode only in that the same target vehicle speed is provided for the left and right rear wheels and in that control using the switching valve VVA is performed. The same is done. First, after data is input at Z1, a target vehicle speed VTR is set at Z2 using the accelerator opening and the shift position of the transmission 4 as parameters. Next, at Z3, it is determined whether or not a value obtained by subtracting the actual wheel speed VBL of the left rear wheel 1RL from the target vehicle speed VTR is higher than a predetermined speed V1. When the determination in Z3 is NO, it is determined that the drive assist by the forward drive is not necessary, and the forward drive of the left rear wheel is stopped in Z13. The processing of Z3 and Z13 is performed for the right rear wheel 1RR independently of the left rear wheel 1RL. The predetermined speed V1 is set to a speed indicating a slip amount sufficient for acceleration, but may be a constant value or a variable value that increases as the vehicle speed VA increases. If the determination in Z3 is YES, it is determined whether or not the accelerator is fully closed in Z4. If the determination in Z4 is YES, the motor M
It is determined that driving assistance using L and MR is not necessary, and the process proceeds to Z13 (in this case, the left and right rear wheels 1R
L and 1RR are stopped at the same time. If the determination in Z4 is NO, in Z5, the lateral G acting on the vehicle body is calculated based on the vehicle speed VA and the steering angle. Thereafter, in Z6, the correction coefficients k1 and k2 are set. Then, in Z7, it is determined whether or not the vehicle is turning right. If the determination in Z7 is YES, in Z9, the left rear wheel 1RL
Is the target vehicle speed VTR determined by Z2.
TR is calculated by multiplying TR by a correction coefficient k1, and similarly, target wheel speed VTRR of right rear wheel 1RR is calculated by multiplying target vehicle speed VTR by correction coefficient k2. If NO in Z7, the target wheel speeds of the left and right rear wheels 1RL, 1RR are calculated in Z8. In short, the processing of Z6 to Z9 corresponds to processing of increasing the target wheel speed on the turning outer wheel side and decreasing the target wheel speed on the turning inner wheel side. However, when the vehicle is going straight, the determination of Z7 is NO and the process proceeds to Z8. At this time, since the correction coefficient is 1, the horizontal G is 0 or almost 0.
), The target wheel speeds of the left and right rear wheels 1RL, 1RR are equal to each other). After Z8 or Z9, at Z10, the target wheel speed VTRL (VTRR) is changed from the rear wheel 1RL.
(1RR) The amount of oil liquid Q supplied to the motor ML (MR) according to the value obtained by subtracting the actual wheel speed VBL (VBR).
Is determined. This oil liquid amount Q is determined by the left and right motors ML, M
R is determined independently of each other. Then, in Z11, the switching valves VVB · L and VVB · R are individually controlled so as to realize the determined oil liquid amount Q. At Z12, it is determined whether or not a value obtained by subtracting the actual wheel speed VBL of the left rear wheel 1RL from the vehicle speed VA is smaller than a predetermined speed "-V2". This Z
In the end, the determination of 12 is to determine whether or not the actual wheel speed VBL of the left rear wheel 1RL is too high compared to the vehicle speed VA. If the determination of Z12 is YES, Z1
In 3, so that the rear wheel maintains a predetermined slip value,
Correction for reducing the supply flow rate Q is performed. Note that Z1
2, the processing of Z13 is similarly performed for the right rear wheel 1RR. If the determination in Z12 is NO, Z13
Is returned without going through. In the positive drive control in the integrated mode, Z
5 to Z9 become unnecessary, and the target vehicle speed VTR determined in Z2 becomes the target wheel speed VT of the left and right rear wheels 1RL, 1RR.
RL and VTRR. In addition, a switching valve VVA is used to realize the flow rate Q at Z11. Although the embodiment has been described above, the present invention is not limited to this, and includes, for example, the following case. (1) The left and right rear wheels 1RL and 1RR may be driven by the engine 2, and the left and right front wheels 1FL and 1FR may be driven by the motors ML and MR. (2) The motors ML and MR may be electrically driven. In this case, in order to obtain an action corresponding to the hydraulic lock mode,
What is necessary is just to perform the opening control of the motor. (3) When it is not necessary to independently control the driving of the left and right auxiliary driving wheels, the motors are not provided independently of the left and right.
Only one may be used for both the left and right sides (a differential device is provided when performing auxiliary driving by the motor during turning). (4) In FIG. 3, when the vehicle is going straight forward at low speed, the forward drive may be executed in either the independent mode or the integrated mode, regardless of the sudden acceleration or the slow acceleration. Good. Also, when the determination in E5 of FIG. 3 is NO,
The positive drive may not be performed. Further, when the determination in E9 of FIG. 3 is NO, the positive drive may be performed on the assumption that rapid acceleration is performed.

[Brief description of the drawings] FIG. 1 is a diagram showing an example of a hydraulic system used in the present invention. FIG. 2 is a diagram illustrating an example of a control system. FIG. 3 is a flowchart showing a control example of the present invention. FIG. 4 is a flowchart showing a control example of the present invention. [Explanation of symbols] U1: Control unit (for motor control) P: Pump ML, MR: Motor 1FL, 1FR: Front wheel 1RL, 1RR: rear wheel 2: Engine 4: Transmission 5: Differential device 71: Connecting passage VVD: On-off valve

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Claims (1)

(57) [Claim 1] One of the left and right front wheels and the left and right rear wheels is a main drive wheel driven by an engine via a transmission and a differential, and the other is A pair of left and right motors are provided so that the left and right auxiliary drive wheels can be driven independently of each other; On condition that the vehicle is accelerating, a positive driving force, which is a driving force in the same direction as the traveling direction of the vehicle, is applied to the motor.
Motor control means for causing the left and right motors to drive in common so that the left and right auxiliary drive wheels have the same rotational speed when the vehicle is slowly accelerating. The motors are independently controlled under independent driving conditions so that the left and right motors have target rotational speeds set independently of each other during rapid acceleration of the vehicle. A vehicle drive device characterized by the above-mentioned.