JP2005265167A - Driving controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the occurrence of unnecessary driving force when an accelerator opening degree becomes nearly 0 in the condition that an electric motor is controlled and driven in the case that a wheel and a pump are driven by the same electric motor. <P>SOLUTION: A transmission mechanism 9 is installed between an electric motor 3 and rear wheels 1RL/1RR, and the transmission ratio is changed on a speed-up side by shifting the transmission mechanism 9 to a high gear from a low gear (step S4) if the requested drive torque TA becomes less than the predetermined value T1 (judgment of step S3 is "No") corresponding to the creep torque value, for example, 0.5 Nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle drive control device capable of driving wheels with an electric motor.

Conventionally, for example, there is a standby type four-wheel drive vehicle in which front wheels are driven by an engine and rear wheels can be driven by an electric motor via a power transmission mechanism such as a clutch (see Patent Document 1).
JP 2003-159953 A

By the way, in the conventional example described in the above Patent Document 1, it is conceivable to provide an oil pump for circulating oil in order to cool the electric motor or lubricate the power transmission mechanism. For driving the oil pump, it is desirable to also use an electric motor for driving wheels in order to suppress an increase in cost.
However, if the wheel drive and the pump drive are combined with a single electric motor, when the vehicle is traveling with a four-wheel drive, for example, even if the accelerator opening is reduced to approximately 0 on a downhill, the cooling of the electric motor and the power transmission mechanism If the pump drive is continued for the purpose of such lubrication, an unnecessary driving force is generated and the driver feels uncomfortable. Here, it is conceivable that the power transmission from the electric motor to the wheels is interrupted by a clutch. However, in a scene where auxiliary driving by the electric motor is required, such as when the friction coefficient of the road surface is low, the vehicle behavior is caused by a shock when the clutch is disconnected. Can disturb.
Therefore, the present invention has been made paying attention to the above problem, and when the wheel drive and the pump drive are combined with one electric motor, the accelerator opening becomes substantially zero in a state where the electric motor is driven and controlled. It is an object of the present invention to provide a vehicle drive control device that can suppress generation of unnecessary driving force when the vehicle is driven.

  In order to solve the above problems, the vehicle drive control device according to the present invention combines the wheel drive and the pump drive with a single electric motor to supply the required drive torque and oil according to the driver's accelerator operation. The motor is driven and controlled according to the required pump driving torque, and the required driving torque is less than or equal to a predetermined value in a state where a speed change mechanism is interposed between the motor and the wheel and the motor is driven and controlled. It is characterized by changing the speed ratio of the speed change mechanism to the speed increasing side.

  According to the present invention, when the required drive torque becomes a predetermined value or less in a state where the drive of the electric motor is being controlled, that is, when the accelerator opening is substantially zero, the speed change mechanism interposed between the electric motor and the wheel is By changing the gear ratio to the speed increasing side, it is possible to reduce the transmission torque from the electric motor to the wheels and suppress the generation of unnecessary driving force while continuing cooling and lubrication by driving the pump.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, in which front wheels 1FL and 1FR are main drive wheels that are driven by an engine 2, and rear wheels 1RL and 1RR are auxiliary drive wheels that can be driven by an electric motor 3. This is a standby type four-wheel drive vehicle.
The power of the engine 2 is transmitted to the front wheels 1FL and 1FR via an automatic transaxle 4 having a torque converter, and is also transmitted to a generator 6 via a V-belt 5. The generator 6 can generate electric power using the power from the engine 2, and the generated electric power is transmitted through a power cable 7. For example, a DC is converted into alternating current by a pulse width modulation (PWM) inverter 8 and then the electric power is generated. It is supplied to the motor 3. The power of the electric motor 3 is transmitted to the rear wheels 1RL and 1RR through the transmission mechanism 9, the electromagnetic clutch 10, and the differential gear 11 in this order, and is also transmitted to the coaxially driven oil pump 12.

The generator 6 incorporates a transistor type regulator, and the regulator adjusts the field current Ig according to the power generation control command from the 4WD controller 13, thereby controlling the power generation voltage of the generator 6.
The inverter 8 controls the drive of the electric motor 3 by controlling the duty ratio of the switching element in accordance with a motor control command from the 4WD controller 13.
The transmission mechanism 9 includes a gear-type transmission mechanism that can be switched to a low gear (for example, a gear ratio of 2.0) and a high gear (for example, a gear ratio of 0.3), and the low gear according to a transmission control command from the 4WD controller 13. Alternatively, switching control is performed to a high gear.
The electromagnetic clutch 10 is composed of an excitation operation type clutch that is engaged when an excitation current is applied, and is engaged when the electric motor 3 is driven and controlled.

  As shown in FIG. 2, the oil pump 12 sucks the oil stored in the oil pan 14 through the oil strainer 15 and discharges it through the oil filter 16. When the hydraulic pressure on the discharge side of the oil pump 11 exceeds a predetermined pressure, the regulator valve 17 bypasses part or all of the oil to the suction side, and the relief valve 18 is upstream due to clogging of the oil filter 16 or the like. When the oil pressure exceeds a predetermined pressure, part or all of the oil is bypassed downstream. In order to maintain a stable oil temperature, for example, a cooling type or air cooling type oil cooler for forcibly cooling the oil may be interposed between the oil pump 12 and the oil filter 16.

  The discharged oil passes through the motor cooling unit 19 and the transmission mechanism lubrication unit 21 via the feeder 20 in order, and then returns to the oil pan 12 again. Here, the motor cooling unit 19 is configured by an oil passage formed near the switching element of the inverter 8 or between the stator of the electric motor 3 and the motor housing, for example. The feeder 20 is configured by a pipe that drops oil on a transmission mechanism lubrication portion 21 that includes various friction surfaces of the transmission mechanism 9, the electromagnetic clutch 10, and the differential gear 11, or a nozzle that injects or sprays oil. .

The 4DW controller 13 includes an accelerator opening Acc detected by the accelerator sensor 22, ON / OFF of the 4WD switch 23 operated by the driver, an engine rotation speed Ne detected by the engine rotation sensor 24, and a wheel rotation sensor 25FL. The wheel speeds Vw _{FL to} Vw _RR detected at ˜25RR, the rotation speed Nm of the electric motor 3 detected by the motor rotation sensor 26, the current Im of the electric motor 3 detected by the current sensor 27, and the temperature sensor 28 The motor temperature Tm and the oil temperature T detected by the oil temperature sensor 29 attached to the oil supply path are input.

Next, the 4WD control process of the first embodiment executed by the 4WD controller 13 will be described with reference to the flowchart of FIG.
This 4WD control process is processed by a timer interrupt every predetermined time (for example, 10 msec) when the 4WD switch 23 is turned on, and first, various data are read in step S1. Specifically, the accelerator opening degree Acc, the engine speed Ne, the wheel speeds Vw _{FL to} Vw _RR , the motor speed Nm, the motor current Im, the motor temperature Tm, and the oil temperature T are included.

In the subsequent step S2, the driver's requested drive torque TA is calculated from the accelerator opening Acc with reference to the control map of FIG.
In the subsequent step S3, it is determined whether or not the required drive torque TA is greater than a predetermined value T1 of, for example, about 0.5 [N · m] corresponding to the creep torque value. Here, when the required drive torque TA is equal to or less than the predetermined value T1, the process proceeds to step S4, a shift control command for shifting from the low gear to the high gear is output to the transmission mechanism 9, and the process proceeds to step S7 described later. On the other hand, when the required drive torque TA is larger than the predetermined value T1, the process proceeds to step S5.

  In step S5, it is determined whether or not the transmission mechanism 9 is shifted to the low gear. Here, when the transmission mechanism 9 is shifted to the high gear, the process proceeds to step S6, and a shift control command for shifting from the high gear to the low gear is output to the transmission mechanism 9, and the process proceeds to step S7. On the other hand, when the transmission mechanism 9 is shifted to the low gear, the process proceeds to step S7 as it is.

In step S7, the oil viscosity μ is calculated from the oil temperature T. This calculation is performed with reference to a control map in which the oil viscosity μ increases as the oil temperature T decreases. The oil temperature T is directly detected by the oil temperature sensor 29 attached to the oil supply path, but may be estimated from the temperatures of the electric motor 3 and the inverter 8.
In the subsequent step S8, the cooling pump rotational speed NC required for supplying a predetermined amount of oil to the motor cooling unit 19 is calculated according to the motor temperature Tm. This calculation is performed with reference to a control map in which the cooling pump rotational speed NC increases as the motor temperature Tm increases.

In step S9, the lubrication pump speed NL necessary to supply a predetermined amount of oil to the transmission mechanism lubrication unit 21, the friction speed of the power transmitting mechanism lubricating unit 21 (e.g., the rear wheel speed Vw _RL · Vw _RR It is calculated according to the average value and vehicle speed. This calculation is performed with reference to a control map in which the lubrication pump rotational speed NL increases as the friction speed of the transmission mechanism lubrication unit 21 increases. If the oil viscosity μ decreases as the oil temperature T rises, a normal oil film cannot be formed on the transmission mechanism lubrication part 21 and the lubrication effect decreases. Therefore, the lubrication pump rotational speed NL depends on the oil temperature T or the oil viscosity. It is desirable to correct by μ.

In the subsequent step S10, as shown in the following equation (1), the larger one of the cooling pump rotational speed Nc and the lubricating pump rotational speed NL is calculated as the required pump rotational speed NP.
NP = max [NC, NL] (1)
In the subsequent step S11, the pump driving torque TP is calculated. First, assuming that the torque required to generate the required hydraulic pressure is the hydraulic torque Tp and the resistance due to the oil viscosity is the sliding torque Ts, the pump driving torque TP is expressed by the following (2).
TP = Tp + Ts (2)

When the oil flow rate is Q, the theoretical discharge amount is q, and the volumetric efficiency is η, the hydraulic torque Tp is expressed by the following equation (3), and the sliding torque Ts is expressed by the following equation (4).
Tp = μ × Q
= Μ × q × η × NP (3)
Ts = μ × NP (4)
From the above equations (2) to (4), the pump driving torque TP is expressed by the following equation (5).
TP = μ × NP × (q × η + 1) (5)

Since the theoretical discharge amount q and the volumetric efficiency η are determined by the mechanical specifications of the oil pump 12, the pump drive torque TP is calculated according to the oil viscosity μ and the required pump speed NP from the above equation (5). To do.
In subsequent step S12, a target motor torque Tm ^* is calculated. Since the wheel drive and the pump drive are shared by the single electric motor 3, the target motor torque Tm ^* is calculated according to the following equation (6). Here, Rt is the speed ratio of the speed change mechanism 9, and Rd is the speed reduction ratio of the differential gear 11.
Tm ^* = TA / (Rt × Rd) + TP (6)

In the subsequent step S13, a target motor current Im ^* to be supplied to the electric motor 3 is calculated based on the target motor torque Tm ^* , the motor rotation speed Nm, and the current value Im, and the generator is generated based on the target motor current Im ^*. The target power P ^* to be generated at 6 is calculated.
In the subsequent step S14, the generator 6 and the electric motor 3 are driven and controlled, and then the process returns to a predetermined main program. That is, the target field current Ig ^* is calculated such that the power generated by the generator 6 matches the target power P ^*, and the generator 6 is driven and controlled by outputting a power generation control command corresponding to the target field current Ig ^*. To do. Further, the duty ratio of the switching element of the inverter 8 is calculated based on the target motor current Im ^* , and a motor control command corresponding to the duty ratio is output to the inverter 8 to drive control the electric motor 3.

  As described above, the inverter 8 and the electric motor 3 correspond to the “motor”, the motor cooling unit 19 corresponds to the “predetermined cooling unit”, the transmission mechanism lubrication unit 21 corresponds to the “predetermined lubrication unit”, and the process of step S2 Corresponds to “required drive torque calculation means”, the processing in steps S7 to S11 corresponds to “pump drive torque calculation means”, the processing in steps S12 to S14 corresponds to “drive control means”, and steps S3 to S6. This process corresponds to “shift control means”. Further, the process of step S7 corresponds to “viscosity detection means”, and the process of steps S8 to S10 corresponds to “required rotational speed calculation means”.

Next, operations and effects of the above embodiment will be described.
Assuming that the vehicle is traveling in a four-wheel drive state, the electric motor 3 is driven and controlled according to a target motor torque Tm ^* that covers both the required drive torque TA and the pump drive torque TP. The rear wheel drive by the electric motor 3 exhibits smooth and stable start performance and running performance. In addition, the pump drive by the electric motor 3 causes overheating of the inverter 8 and the electric motor 3 by heat exchange between the oil and the motor cooling unit 19 by forcibly circulating oil through the motor cooling unit 19 and the transmission mechanism lubrication unit 21. In addition to preventing, an oil film can be formed on various friction surfaces of the transmission mechanism 9, the electromagnetic clutch 10, and the differential gear 11 to perform appropriate lubrication.

  Here, the pump drive torque TP is calculated according to the required pump speed NP and the oil viscosity μ necessary for supplying oil to the motor cooling unit 19 and the transmission mechanism lubrication unit 21 (steps S7 to S7). S11), an appropriate pump drive torque TP can be calculated according to fluid parameters such as the overheating state of the motor cooling unit 19, the lubrication state of the transmission mechanism lubrication unit 21, and the oil viscosity μ.

  In addition, when the oil supply path from the oil pump 12 to the motor cooling unit 19 and the transmission mechanism lubrication unit 21 is arranged in series, the required pump speed NP is necessary to supply oil to the motor cooling unit 19. Since the larger value of the cooling pump rotational speed NC and the lubricating pump rotational speed NL necessary for supplying oil to the transmission mechanism lubrication unit 21 is selected (step S10), The necessary pump rotation speed NP can be calculated without any shortage.

Further, since the cooling pump rotational speed NC is calculated according to the motor temperature Tm detected by the motor temperature sensor 28 (step S8), the cooling pump rotational speed NC can be easily calculated.
Additionally, lubricating pump rotational speed NL, the friction speed of the power transmitting mechanism lubrication unit 21, i.e. because it is calculated in accordance with the average value of the wheel speed Vw _RL · Vw _RR after detecting the wheel speed sensor 25RL · 25RR (step S9), the lubrication pump rotational speed NL can be easily calculated.

Further, since the oil viscosity μ is calculated according to the oil temperature T detected by the oil temperature sensor 29 (step S7), the oil viscosity μ can be easily calculated.
By the way, when the wheel drive and the pump drive are combined with one electric motor 3 as described above, the required drive torque TA is not more than a predetermined value T1 close to 0 on a downhill, for example, when traveling by four-wheel drive. However, if the pump drive is continued for the purpose of cooling or lubrication, an unnecessary driving force is generated.

  Therefore, in the present invention, when the required drive torque TA becomes equal to or less than the predetermined value T1 (determination in step S3 is “No”), the transmission mechanism 9 interposed between the electric motor 3 and the rear wheels 1RL and 1RR is used. The gear ratio is changed to the speed increasing side, that is, the low gear is shifted to the high gear (step S4). Thereby, even if the pump drive by the electric motor 3 is continued, the transmission torque to the rear wheels 1RL and 1RR can be reduced, and generation of unnecessary driving force can be suppressed. In addition, since the transmission torque to the rear wheels 1RL and 1RR is not cut off, it is necessary to sufficiently increase the speed ratio to such an extent that the driver does not feel uncomfortable and to suppress the generation of driving force.

The predetermined value T1 for the required drive torque TA is set to, for example, about 0.5 [N · m] corresponding to the creep torque value of the automatic transaxle 4. As a result, it is possible to omit strict torque control in an extremely low torque region where the required drive torque TA is smaller than 0.5 [N · m], for example.
In the first embodiment, the oil is supplied to the transmission mechanism lubrication unit 21 via the feeder 20, but the present invention is not limited to this, and the transmission mechanism lubrication unit 21 is stored inside the casing. Any other lubrication method may be employed, such as an oil bath type immersed in the oil or a total loss type in which the oil supplied to the transmission mechanism lubrication unit 21 is not recovered.

In the first embodiment, a gear-type transmission mechanism is employed as the transmission mechanism 9 interposed between the electric motor 3 and the rear wheels 1RL and 1RR. However, the present invention is not limited to this. . In short, any transmission mechanism such as a planetary gear type transmission mechanism or a continuously variable transmission (CVT) may be employed as long as the transmission power from the electric motor 3 to the rear wheels 1RL and 1RR can be changed.
Moreover, although said 1st Embodiment has demonstrated the case where oil is supplied to both the motor cooling part 19 and the transmission mechanism lubrication part 21, it is not limited to this, It supplies to either one Even in this case, the present invention can be applied.

In the first embodiment, the timing for increasing the speed ratio of the speed change mechanism 9 is determined according to the required drive torque TA, but the present invention is not limited to this. Since the required drive torque TA is calculated according to the accelerator opening Acc, the speed increase timing of the gear ratio may be determined according to the accelerator opening Acc.
Furthermore, in the first embodiment, the case where the 4WD control is executed when the 4WD switch 23 is turned on has been described, but the present invention is not limited to this. For example, when the vehicle starts with the 4WD switch 23 ON and reaches a predetermined vehicle speed (for example, 30 km / h), or when a slip of the front wheels 1FL and 1FR driven by the engine 2 is detected, 4WD control is performed. May be executed.

Furthermore, in the first embodiment described above, the electric power generated by the generator 6 is supplied only to the electric motor 3. However, the present invention is not limited to this, and the battery, ignition device, starting device, air conditioner, etc. You may supply to an electrical component.
Furthermore, in the first embodiment described above, the front wheels 1FL and 1FR are the main drive wheels that are driven by the engine 2, and the rear wheels 1RL and 1RR are the auxiliary drive wheels that can be driven by the electric motor 3, but this is not limitative. Instead of this, the rear wheels 1RL and 1RR may be the main drive wheels, and the front wheels 1FL and 1FR may be the auxiliary drive wheels.
Furthermore, in the first embodiment, the present invention is applied to a four-wheeled vehicle, but may be applied to a two-wheeled vehicle, a three-wheeled vehicle, or a vehicle having five or more wheels.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, as shown in FIG. 5, oil supply paths from the oil pump 12 to the motor cooling unit 19 and the transmission mechanism lubrication unit 21 are arranged in parallel. In this case, in order to supply a predetermined amount of oil to each of the motor cooling unit 19 and the transmission mechanism lubrication unit 21, the calculation of the pump required rotational speed is different from that in the first embodiment described above.
That is, the turning control process of the second embodiment is the same as the 4WD control process of FIG. 3 except that the process of step S10 of FIG. 3 is changed to a new step S20 as shown in FIG. Execute the process. 3 corresponding to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

In step S20, as shown in the following equation (7), the sum of the cooling pump rotational speed NC and the lubricating pump rotational speed NL is calculated as the pump required rotational speed NP.
NP = NC + NL (7)
Thus, when the oil pump supply path from the oil pump 12 to the motor cooling unit 19 and the transmission mechanism lubricating unit 21 is arranged in parallel, the required pump speed NP supplies oil to the motor cooling unit 19. Is calculated by adding the cooling pump rotational speed NC necessary for the operation and the lubricating pump rotational speed NL necessary for supplying the oil to the transmission mechanism lubrication unit 21 (step S20). Necessary rotational speed NP can be calculated. Here, the processing of steps S8, S9, and S20 corresponds to “necessary rotational speed calculation means”.
Other functions and effects are the same as those of the first embodiment described above.

It is a schematic block diagram of this invention. It is an oil system diagram of a 1st embodiment. It is a flowchart which shows 4WD control processing of 1st Embodiment. It is a control map for request | requirement drive torque calculation. It is an oil system diagram of a 2nd embodiment. It is a flowchart which shows 4WD control processing of 2nd Embodiment.

Explanation of symbols

1FL, 1FR Front wheel 1RL, 1RR Rear wheel 2 Engine 3 Electric motor 6 Generator 8 Inverter 9 Transmission mechanism 10 Electromagnetic clutch 11 Differential gear 12 Oil pump 13 4WD controller 19 Electric motor cooling section 21 Transmission mechanism lubrication section 22 Acceleration sensor 23 4WD switch 25FL ~ 25RR Wheel rotation sensor 28 Motor temperature sensor 29 Oil temperature sensor

Claims (8)

An electric motor that can drive the wheel, an oil pump that is connected to the electric motor and supplies oil to at least one of the predetermined cooling unit and the predetermined lubricating unit while the vehicle is running, and calculates the required driving torque according to the driver's accelerator operation Required drive torque calculating means, pump drive torque calculating means for calculating pump drive torque required to supply the oil by the oil pump, required drive torque calculated by the required drive torque calculating means, and pump drive In a vehicle drive control device comprising: drive control means for driving and controlling the electric motor according to the pump drive torque calculated by the torque calculation means;
A speed change mechanism interposed between the motor and the wheel, and a speed change of the speed change mechanism when the required drive torque becomes a predetermined value or less in a state where the drive control means drives and controls the motor. Shift control means for changing the ratio to the speed increasing side, and a vehicle drive control device.   The pump driving torque calculation means detects a necessary rotation speed calculation means for calculating a pump required rotation speed required to supply the oil to at least one of the predetermined cooling section and the predetermined lubrication section, and detects the viscosity of the oil. The pump drive torque is calculated according to a required pump speed calculated by the required speed calculating means and a viscosity of the oil detected by the viscosity detecting means. The vehicle drive control device according to claim 1.   The required rotational speed calculation means is a cooling pump required to supply the oil to the predetermined cooling section when an oil supply path from the oil pump to the predetermined cooling section and the predetermined lubricating section is arranged in series. The rotational speed and the lubrication pump rotational speed required to supply the oil to the predetermined lubrication unit are calculated, and the larger one of the cooling pump rotational speed and the lubricating pump rotational speed is the pump required rotational speed. The vehicle drive control device according to claim 2, wherein   The required rotational speed calculating means is a cooling pump required for supplying the oil to the predetermined cooling section when oil supply paths from the oil pump to the predetermined cooling section and the predetermined lubricating section are arranged in parallel. Calculate the number of rotations and the number of rotations of the lubrication pump required to supply the oil to the predetermined lubrication unit, and set the sum of the number of rotations of the cooling pump and the number of rotations of the lubrication pump as the number of rotations required for the pump. The vehicle drive control device according to claim 2.   5. The vehicle drive control device according to claim 3, wherein the required rotational speed calculation unit calculates the cooling pump rotational speed in accordance with a temperature of the predetermined cooling unit.   The vehicle drive control device according to any one of claims 3 to 5, wherein the necessary rotation speed calculation means calculates the lubrication pump rotation speed in accordance with a friction speed of the predetermined lubrication portion. .   The vehicular drive control device according to any one of claims 2 to 6, wherein the viscosity detection means detects the viscosity according to the temperature of the oil.   The vehicle drive control apparatus according to any one of claims 1 to 7, wherein the predetermined value for the required drive torque is set to a creep torque value.

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