JP2002010407A - Creep control device for vehicle provided with electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To property control creep torque with existing equipment, without having to newly add sensors. SOLUTION: The creep control device controls creep torque as follows: enable from the shift position set in the forward traveling enable range (D range, etc.), while stepping on the brake to stop the vehicle, the pedaling force is released to start the vehicle and calculates a speed of rotation Np of the primary pulley of CVT (S14), and controls a motor B command torque Tb to obtain the speed of rotation Np of the primary pulley so that it is in the range of 690 rpm<=700 rpm (3-8 km/h) (S19-S22). In this case, the speed of rotation Np of the primary pulley is calculated, based on a speed of rotation Nr of a ring gear interposed linked with the drive motor B of a planetary gear unit, which is interposed between an engine output shaft and the primary pulley, and a speed of rotation Ns of a sun gear which is connected to the engine output shaft. Since the speed of rotation Nr of the ring gear detects the speed of rotation of the motor B and the speed of rotation of the sun gear Ns detects the engine speed, the creep torque can be controlled with the existing equipment, as is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a creep control device for a vehicle equipped with an electric motor, wherein a creep torque is generated by an electric motor.

[0002]

2. Description of the Related Art Normal A using an engine as a power source for traveling
In a T-car (a vehicle in which a torque converter and an automatic transmission are combined), the accelerator pedal is depressed when the shift is set to a driving range such as the D range due to creep torque generated from the torque converter. At least, the vehicle is set to run at a very low speed, and the creep torque allows the vehicle speed to be controlled only by adjusting the brake depression when entering a garage or in a traffic jam.

On the other hand, even vehicles with an electric motor, such as electric vehicles and hybrid vehicles, which use an electric motor as a main drive source, generate a creep torque similar to that of a normal AT vehicle to convert the vehicle from an AT vehicle to a vehicle with an electric motor. If you transfer,
Various technologies have been proposed that enable operation without discomfort.

For example, Japanese Unexamined Patent Publication No. Hei 6-261416 discloses an output torque of an electric motor for generating a creep torque such that the actual vehicle speed becomes very slow when the vehicle is running close to a stop with a brake pedal depressed. There is disclosed a technique for increasing or decreasing the number.

That is, according to the technology disclosed in this publication, a tilt angle sensor for detecting a vehicle tilt angle in order to obtain an appropriate creep torque irrespective of a difference in driving conditions such as a road surface gradient and a vehicle weight, A weight sensor for detecting the vehicle weight is provided to read the basic creep control amount and the learning control amount according to the inclination angle and the vehicle weight, and to perform the creep torque control of the electric motor.

[0006]

However, according to the technology disclosed in the above publication, the creep torque can be properly controlled unless a special sensor such as an inclination sensor or a weight sensor which is not used in normal control is newly added. However, it is difficult to apply the method to an existing vehicle equipped with an electric motor, and therefore, there is a problem that the versatility is lacking.

In view of the above circumstances, the present invention can appropriately control the creep torque with existing equipment without newly adding sensors, suppress a rise in product cost, and have excellent versatility. It is another object of the present invention to provide a creep control device for a vehicle with an electric motor.

[0008]

In order to achieve the above object, the present invention relates to a creep control device for an electric motor-equipped vehicle having an electric motor for generating a creep torque at a low vehicle speed. The torque of the electric motor is controlled so that the output rotation speed of the motor is maintained at the set rotation speed.

With such a configuration, when traveling at a very low speed,
The torque of the electric motor is controlled so as to generate a constant creep torque so that the output rotation speed of the electric motor is maintained at the set rotation speed.

In this case, it is preferable that the movement in the descending direction is detected based on the output rotation speed of the electric motor and the type of the traveling range detected by the traveling range detecting means. It is characterized in that the torque of the motor is controlled.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration diagram of a drive system of a hybrid vehicle.

In this embodiment, a hybrid vehicle is shown as an example of a vehicle with an electric motor. This hybrid vehicle is a parallel hybrid vehicle that uses an engine and two electric motors A and B in combination. The hybrid vehicle is directly connected to an engine 1 and an output shaft 1a of the engine 1 to start the engine 1 and generate power and assist power. A power generating motor A, a single-pinion planetary gear unit 3 connected to an output shaft 1a of the engine 1 extending from the power generating motor A,
A single-pinion type planetary gear unit 3 controls the function of the driving motor B, which serves as a driving force source at the time of starting and reversing and collects deceleration energy, and a power conversion function at the time of traveling by performing speed change and torque amplification. The drive system is basically provided with a continuously variable transmission 5 which carries the drive system.

The planetary gear unit 3 has a sun gear 3a, a carrier 3b rotatably supporting a pinion meshing with the sun gear 3a, and a ring gear 3c meshing with the pinion. The sun gear 3a and the ring gear 3c
And a lock-up clutch 6 for engaging and releasing the lock.

The continuously variable transmission 5 has an input shaft 5a.
The drive belt 5e is wound around a primary pulley 5b supported on the output shaft 5c and a primary pulley 5b supported on the output shaft 5c.
Description will be given as T5.

That is, in the drive system of the hybrid vehicle according to the present embodiment, the planetary gear unit 3 having the lock-up clutch 6 interposed between the sun gear 3a and the ring gear 3c includes the output shaft 1a of the engine 1 and the input shaft 5a of the CVT 5. The sun gear 3a of the planetary gear unit 3 is connected to the output shaft 1a of the engine 1 via the motor A for power generation, the carrier 3b is connected to the input shaft 5a of the CVT 5, and the ring gear 3c The driving motor B is connected. A differential mechanism 8 is connected to an output shaft 5c of the CVT 5 via a reduction gear train 7, and a drive shaft 9 is connected to the differential mechanism 8.
The drive wheels 10 of the front wheels or the rear wheels are connected to each other through the wheels.

In this case, as described above, the engine 1 and the power generation motor A are coupled to the sun gear 3a of the planetary gear unit 3 and the driving motor B is connected to the ring gear 3c.
Are combined to obtain an output from the carrier 3b, and the output from the carrier 3b is transmitted to the drive wheels 10 by shifting and amplifying the torque by the CVT 5 so that the two electric motors A and B generate electric power. And drive power supply.

Further, the sun gear 3a of the planetary gear unit 3 is
And the ring gear 3c, a drive system directly connected to the engine from the engine 1 to the CVT 5 in which the two electric motors A and B are arranged can be formed.

This drive system is basically centrally controlled by a hybrid system control ECU (HEV_ECU) 15. The HEV_ECU 15 includes a microcomputer and a functional circuit controlled by the microcomputer.

The HEV_ECU 15 includes sensors and switches for detecting a driver's driving operation status, for example, an accelerator pedal sensor (APS) 22 for detecting an amount of depression of an accelerator pedal (not shown), and a brake which is turned on by depressing a brake pedal (not shown). Switch 23,
A shift range switch 24, which is an example of running range detecting means for detecting whether or not the shift position is set to a running range such as D, Ds (sport mode), and R range, and an engine speed sensor 25 are connected. Have been.

The HEV_ECU 15 controls the engine 1 and shifts the CVT 5 based on signals from the sensors and switches, controls the driving of the electric motors A and B, and further locks up the clutch. 6
Control intermittent interruptions.

The HEV_ECU 15 controls the torque of the driving motor B to generate a creep torque that keeps the vehicle speed constant when the vehicle is in a running condition close to a stopped state.

This creep torque control is, specifically,
The processing is performed according to the flowcharts shown in FIGS.
These are set at predetermined intervals (for example, 10 m
s).

In the normal creep torque control determination routine shown in FIG. 2, in steps S1 to S4, it is checked whether or not the vehicle is in a normal creep torque control region.

First, in step S1, it is determined whether or not the shift position has been set to the travelable range (D, Ds, R range) based on the output signal of the shift range switch 24, and is set to the travelable range. If so, the process proceeds to step S2. If the range is set to a range (P, N range, etc.) other than the range in which the vehicle can travel, the process jumps to step S6.

At step S2, it is determined whether or not the accelerator pedal is open based on the output signal of the APS 22. When the accelerator pedal is open, the process proceeds to step S3.
If the accelerator pedal is depressed, step S
Jump to 6.

In step S3, the rotational speed (primary pulley rotational speed) Np of the primary pulley 5b is calculated based on the following equation. Np = (Gr · Nr + Gs · N
s) / (Gr + Gs) (1) where Gs is the number of teeth of the ring gear 3c, Nr is the number of revolutions of the ring gear, Gs is the number of teeth of the sun gear 3a, and Ns is the number of revolutions of the sun gear 3a.

Here, the ring gear 3c is connected to the driving motor B
Since the ring gear 3c and the driving motor B rotate integrally, the rotation number Nr of the ring gear 3c is determined by detecting the motor B rotation number Nb fed back from the driving motor B. (Nb = Nr). In this case, since the resolver that detects the motor B rotation speed Nb can detect positive rotation and negative rotation, the ring gear rotation speed Nr has positive and negative signs, and therefore, the primary pulley rotation speed Np is positive or negative. It has a sign.

Since the sun gear 3a is directly connected to the engine 1, and the engine 1 and the sun gear 3a rotate integrally, the rotation of the sun gear 3a is detected by detecting the engine speed Ne detected by the engine speed sensor 25. The number Ns can be obtained (Ne = Ns). Since the power generation motor A is also directly connected to the engine 1, the sun gear rotation speed Ns can be obtained from the motor A rotation speed Na.

The engine speed sensor 25 is usually provided in parallel with the engine 1 as typified by a crank angle sensor. Therefore, the primary pulley speed Np is calculated from the existing sensors. It can be obtained using detection data, and there is no need to provide special sensors.

Next, the routine proceeds to step S4, where it is checked whether or not the primary pulley rotation speed Np falls within a range of ± 1400 rpm.
Np ≦ 1400), it is determined that the vehicle is traveling at a very low speed, and step S5 is performed.
Proceed to. If it is off (Np <-1400 or 1400 <Np), the process branches to step S6.

The CVT 5 gradually changes the gear ratio as the vehicle speed decreases, and becomes maximum at a vehicle speed close to zero. The speed ratio of the CVT 5 during the slow running is fixed at the maximum value, and therefore, the vehicle speed during the slow running and the primary pulley rotation speed Np are in a proportional relationship. In the present embodiment, the maximum value of the creep traveling vehicle speed is set to 1400 rpm in terms of the primary pulley rotation speed Np, but this is a value corresponding to a vehicle speed of about 10 km / h including backward traveling.

Then, when it is determined that the vehicle is traveling at a very low speed,
In step S5, a creeping flag X_CLP is set (X_CLP = 1), and the routine exits.

On the other hand, when the flow branches to step S6, that is, a running state other than creep running, for example, 10 km / m
h and the shift position is set to a forward drive range such as the D range, and the vehicle is coasted downhill or the shift position is set to the reverse drive range (R
Range), when the vehicle is coasting downhill (the vehicle is backing) or when the shift position is set to a stop range such as the N or P range. Clear X_CLP (X
_CLP = 0), exits the routine.

In the normal creep torque control, the primary pulley rotation speed Np is set to ± 1400 rpm even when the shift position is set in the travelable range (D, Ds, R range) and the accelerator pedal is released.
If it is not within the range, it is determined that the vehicle is coasting in the descending direction, and the vehicle is distinguished from creep traveling.In the subsequent control, unnecessary creep torque control is performed. Therefore, good creep torque controllability can be obtained.

The value of the in-creep flag X_CLP set in step S5 or S6 is read in the creep torque control routine shown in FIGS.

In this routine, first, at step S11
Then, the running state is checked with reference to the value of the in-creep flag X_CLP, and the brake flag X_
The operation state of the foot brake is checked by referring to the value of BRK.

The brake flag X_BRK is set based on the output signal of the brake switch 23. The brake flag X_BRK is set when the brake switch 23 is turned on.
Cleared when FF.

Then, X_CLP = 0 or X_BR
If the brake is depressed with K = 1, step S13
Then, the motor B instruction torque initialization flag X_Tb, which will be described later, is cleared (X_Tb = 0), and the routine exits. On the other hand, in the normal creep torque control state of X_CLP = 1, and when the brake is not depressed in the state of X_BRK = 0, the process proceeds to step S14.

In step S14, it is determined whether or not the shift position is in the forward travelable range (D or Ds range) based on the output signal of the shift range switch 24. Is set to, the process branches to step S23. On the other hand, when it is set to the forward traveling range, the process proceeds to step S15.

Then, in step S15 and subsequent steps, the forward running creep torque control is executed. First, step S1
In step 5, the primary pulley rotation speed Np is calculated by the same calculation method as in step S3 described above.

Thereafter, the process proceeds to step S16, where the motor B
Referring to the value of the instruction torque initial setting flag X_Tb,
Tb = 0, that is, after shifting to the forward running creep torque control, the first routine is executed.
Then, referring to the table with supplementary calculation based on the primary pulley rotation speed Np, the initial value of the motor B instruction torque Tb is set, and in step S18, the motor B instruction torque initial setting flag X_Tb is set (X_Tb =
1) Exit the routine.

As shown in FIG. 6, the table has a forward rotation,
The motor B command torque Tb corresponding to the primary pulley rotation speed Np for both negative rotations is stored. In the forward rotation direction, the motor B instruction torque Tb that decreases as the primary pulley rotation speed Np increases is stored.
In the negative rotation direction, a motor B command torque Tb that decreases as the primary pulley rotation speed Np decreases is stored.

For example, when the foot brake is released to start from a state where the vehicle is stopped on an uphill road, when the foot brake is released, the vehicle retreats for a moment. At this time, in step S15, the vehicle rotates in the negative direction opposite to the forward direction. The primary pulley rotation speed Np is calculated, the initial value of the motor B instruction torque Tb is calculated by referring to the table based on the primary pulley rotation speed Np, and a torque command corresponding to the motor B instruction torque Tb is output to the driving motor B. Therefore, the rotation of the driving motor B generates a creep torque, and the vehicle is prevented from moving backward.

On the other hand, after that, when the routine is executed again and reaches step S16, since the motor B command torque initial setting flag X_Tb is set, the process proceeds to step S19. Control of the driving motor B is performed.

First, in steps S19 and S20, the rotational speed Np of the primary pulley is set to 690 rpm ≦ Np ≦ 700.
Check whether it is in the range of rpm. As mentioned above,
The primary pulley rotation speed Np is proportional to the vehicle speed,
In the present embodiment, the vehicle speed at the time of traveling at a low speed is 3 to 8 km / h.
And the primary pulley rotation speed Np corresponding to this vehicle speed
Is set to 690 to 700 rpm.

If Np <690 rpm, the process proceeds to step S21, in which the creep increment adjusting torque Tca is added to the previously set motor B command torque Tbold.
Calculate the current motor B torque command and exit the routine. Tb = Tbold + Tca In this case, the added value of the motor B instruction torque Tb is 20
A limiter is provided so as to be Nm or less.

On the other hand, if Np> 700 rpm, the routine proceeds to step S22, where the previously set motor B instruction torque T
The current motor B torque command is calculated by subtracting the creep decrement adjustment torque Tcd from bold, and the routine exits. Tb = Tbold−Tcd The subtraction value of the motor B instruction torque Tb at this time is 3N
A limiter is provided so as to be not less than m.

As a result, when the foot brake is released in order to start from a state where the vehicle is stopped on a steep ascending road, as described above, the driving motor B returns to the initial value of the motor B instruction torque Tb set by searching the table. Generate a corresponding creep torque to prevent the vehicle from moving backwards,
The motor B command torque Tb is increased until the vehicle speed (3 to 8 km / h) at which the vehicle can travel at a low speed is maintained, and this vehicle speed is maintained. Therefore, the driver does not need to continuously perform the opening operation of the foot brake and the operation of depressing the accelerator pedal even when starting operation on a steep uphill road, and can perform each operation with a margin. .

In step S14, it is determined that the shift position is set to a range other than the forward traveling range (D or Ds range), and step S2 is performed.
When the routine proceeds to 3, it is checked whether or not the shift position is set in the reverse traveling range (R range). If the shift position is not set in the reverse traveling range (R range), the routine exits.

On the other hand, when the shift position has been set to the R range, the process proceeds to step S24, and after step S24, the creep torque control during reverse running is performed. First, at step S24, at step S3
The primary pulley rotation speed Np is calculated by the same calculation method as that described above.

Next, the routine proceeds to step S25, where the motor B
Referring to the value of the instruction torque initial setting flag X_Tb,
Tb = 0, that is, in the case of executing the first routine after shifting to the reverse running creep torque control, the process returns to step S17 to set the initial value of the motor B instruction torque Tb.

As a result, for example, when the foot brake is released in order to go backward on an uphill from a state where the vehicle is stopped on a downhill road, the vehicle moves forward for a moment. Number Np
Is calculated, the initial value of the motor B command torque Tb is calculated by referring to the table based on the primary pulley rotation speed Np, and a torque command corresponding to the motor B command torque Tb is output to the driving motor B. Creep torque is generated by the rotation of the driving motor B, and the vehicle is prevented from moving forward.

On the other hand, after that, when the routine is executed again and the process proceeds to step S25, since the motor B instruction torque initial setting flag X_Tb is set, the process proceeds to step S28. The torque of the drive motor B is controlled so as to travel.

First, in steps S28 and S29, the primary pulley rotation speed Np is set to -690 rpm ≧ Np ≧ −7.
Check whether it is in the range of 00 rpm. As described above, the primary pulley rotation speed Np is proportional to the vehicle speed, and in the present embodiment, the vehicle speed during slow reverse traveling is 3 to 8
Km / h, and the primary pulley rotation speed Np corresponding to this vehicle speed is set to -690 to -700 rpm.

When Np> -690 rpm,
Proceeding to step S30, the creep increment adjustment torque Tcra is added to the previously set motor B instruction torque Tbold to calculate the current motor B torque command, and the routine exits. Tb = Tbold + Tcra In this case, the added value of the motor B instruction torque Tb is −2.
A limiter is provided so as to be 0 Nm or less.

On the other hand, if Np <-700 rpm, the routine proceeds to step S31, in which the creep decrement adjustment torque Tcrd is subtracted from the previously set motor B command torque Tbold, and the current motor B torque command is calculated. Exit. Tb = Tbold−Tcrd The subtraction value of the motor B instruction torque Tb at this time is −3.
A limiter is provided so as to be Nm or more.

As a result, when the foot brake is released in order to make the vehicle travel backward in the uphill direction from a state where the vehicle is stopped on a steep downhill road, as described above, the driving motor B causes the motor B instruction torque Tb set by the table search as described above. A creep torque corresponding to the initial value is generated to prevent the vehicle from moving in the descending direction, and then the motor B command torque Tb is increased until the vehicle speed (3 to 8 km / h) at which the vehicle can travel at a very low speed is possible. This vehicle speed is maintained. Therefore, the driver does not need to continuously perform the operation of releasing the foot brake and the operation of depressing the accelerator pedal even in the case of a reverse operation on a steep downhill, and can perform each operation with a margin. .

As described above, according to the present embodiment, for example, when starting operation in the forward direction on an uphill road and starting operation in the reverse direction on a downhill road, the shift position and the rotation direction of the primary pulley 5b are used. , Primary pulley 5b
It is determined whether or not the vehicle is rotating in the opposite direction to the original rotation direction, so that the movement of the vehicle in the descending direction can be accurately detected with existing equipment without adding sensors. Can be.

The creep against movement in the descending direction on an uphill road is performed by using the rotation speed Nb (= ring gear rotation speed Nr) of the driving motor B and the engine rotation speed (= sun gear rotation speed Ns). The shortage of the torque is adjusted by increasing or decreasing the torque of the drive motor B so that the vehicle is prevented from moving in the descending direction and the rotational speed of the drive motor B can be increased at a low speed in the uphill direction. Therefore, the driver can perform the starting operation with a margin without panic.

The present invention is not limited to the above-described embodiment. For example, a vehicle provided with an electric motor for generating creep torque is not limited to a hybrid vehicle but may be an electric vehicle.

[0061]

As described above, according to the present invention,
The creep torque can be appropriately controlled with the existing equipment without newly adding sensors, so that an increase in product cost can be suppressed and excellent versatility can be obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a drive system of a hybrid vehicle.

FIG. 2 is a flowchart showing a normal creep torque control determination routine;

FIG. 3 is a flowchart showing a creep torque control routine (part 1);

FIG. 4 is a flowchart showing a creep torque control routine (part 2);

FIG. 5 is an explanatory diagram of a table for setting a motor B instruction torque.

[Explanation of symbols]

24 Shift range switch (running range detecting means) B Drive motor (electric motor) Np Primary pulley rotation speed (output rotation speed of electric motor) Tb Motor B instruction torque

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Claims (2)

[Claims] In a creep control device for an electric motor-equipped vehicle having an electric motor for generating a creep torque at a low vehicle speed, an output rotational speed of the electric motor is maintained at a set rotational speed during a low-speed running. And controlling the torque of the electric motor. 2. A movement in a descending direction is detected based on an output rotation speed of the electric motor and a type of traveling range detected by a traveling range detecting means. When the movement in the descending direction is detected, the torque of the electric motor is detected. The creep control device for a vehicle with an electric motor according to claim 1, wherein the creep control device performs the control.