JP6747235B2 - Hybrid vehicle drive control system - Google Patents

Description

The present invention relates to a drive control system for a hybrid vehicle, which relates to a drive control system for a hybrid vehicle including an engagement mechanism capable of suppressing rotation of a rotating element of a power split mechanism.

The hybrid vehicle described in Patent Document 1 is configured to appropriately transmit the power generated by each of the engine, the first electric motor, and the second electric motor to the drive wheels according to the running state of the vehicle, and the first planetary gear mechanism. And a power split mechanism having a second planetary gear mechanism. The first sun gear of the first planetary gear mechanism is connected to rotate integrally with the first electric motor, the first carrier is connected to rotate integrally with the crankshaft of the engine, and the first ring gear is connected to the first planetary gear mechanism of the second planetary gear mechanism. It is connected so as to rotate integrally with the two carriers. The second sun gear in the second planetary gear mechanism is connected to the hub of the dog clutch so as to rotate integrally therewith, and the second ring gear is connected to rotate integrally with the first carrier. The second electric motor is connected to the drive wheels via the second electric motor transmission unit. The dog clutch includes a hub and a fixing portion fixed to the vehicle body, and the rotation of the second sun gear can be fixed by engaging the hub and the fixing portion. By fixing the rotation of the second sun gear, it is possible to switch to an overdrive state in which the rotation speed of the engine becomes smaller than the rotation speed of the output shaft connected to the drive wheels.

JP2012-193851A

The hybrid vehicle described in Patent Document 1 described above can travel in the HV mode in which the vehicle travels at least by the power of the engine without engaging the dog clutch. When traveling on a low μ road or the like when traveling in the HV mode, the tires provided on the drive wheels may lose grip and slip to slip. In this case, the absolute value of the rotation speed of the drive wheels will increase. At this time, it is necessary to reduce the absolute value of the rotational speed of the drive wheels in order to restore the grip force of the tire again. In order to reduce the absolute value of the rotational speed of the drive wheel, the output of the engine is reduced to reduce the absolute value of the rotational speed of the engine, or the torque of the second electric motor is decreased to decrease the absolute value of the rotational speed of the drive wheel. Can be output. However, when the engine speed is reduced, it takes time until the engine speed is reduced due to inertia of the engine or the like. Therefore, it may take time to recover from the slip state.

In addition, the output torque may decrease due to the high temperature of the second electric motor due to the fact that the second electric motor is continuously driven. In this case, when the torque of the second electric motor is used to recover from the above-mentioned slip state, the torque actually output becomes smaller than the command torque, and therefore it may take time to recover from the slip state. Therefore, when returning from the slip state using the power source such as the engine or the second electric motor, it may take time to return from the slip state depending on the state of the power source.

The present invention has been made in view of the above technical problem, and is a case where the drive wheels slip while traveling by the power of the engine without engaging the engagement mechanism such as the dog clutch. Another object of the present invention is to provide a drive control system for a hybrid vehicle that can recover from a slip state regardless of the drive state of an engine or an electric motor.

To achieve the above object, the present invention provides an engine, an electric motor, drive wheels, a brake mechanism, a first rotating element connected to the engine, and a second rotating element connected to the electric motor. A first differential mechanism including a third rotating element connected to the drive wheel, and a second differential mechanism including at least a fourth rotating element connected to the brake mechanism, and a power split mechanism. The controller that controls the engine, the electric motor, and the brake mechanism, and the brake mechanism are capable of outputting a braking torque that suppresses rotation of the fourth rotating element, and When the rotation speed of the fourth rotation element is suppressed to 0 rotation by the brake mechanism rather than the rotation speed of the third rotation element when the second rotation element is fixed to 0 rotation, when the rotation speed is set to a predetermined value. In the drive control system for a hybrid vehicle, wherein the rotational speed of the third rotating element is increased, the controller causes the drive wheel to slip and the fourth rotating element to cause the first rotating element to rotate. When it is rotating in the opposite direction, the braking mechanism is configured to output a braking torque.

Further, the present invention is characterized in that the controller is capable of detecting a slip amount of the drive wheel, and the braking torque output by the brake mechanism is increased as the slip amount is increased. I am trying.

According to the present invention, when the drive wheel slips while the fourth rotating element is rotating in the direction opposite to the first rotating element, the brake mechanism causes the fourth rotating element to rotate without changing the rotation speed of the first rotating element. The rotation of the rotating element is suppressed. As a result, the reaction force of the braking torque of the brake mechanism applied to the fourth rotating element suppresses the rotation of the third rotating element, so that the slip can be recovered. Since the control can be performed regardless of the state of the power source such as the engine or the electric motor, it is possible to suppress the delay in the return from the slip depending on the state of the power source.

Further, according to the present invention, the braking torque output by the brake mechanism is increased as the slip amount increases, so that the rotation of the third rotating element can be suppressed even when the slip amount is large. Therefore, it is possible to recover from slip.

It is a skeleton figure of the hybrid vehicle concerning the embodiment of the present invention. It is a control conceptual diagram for describing the embodiment of the present invention. FIG. 6 is a collinear diagram for explaining an HV traveling mode according to the embodiment of the present invention. FIG. 6 is a nomographic chart for explaining a slip state according to the embodiment of the present invention. FIG. 6 is a collinear diagram for explaining a case where the brake mechanism according to the embodiment of the present invention is operated. FIG. 6 is a collinear diagram for explaining a case where the brake mechanism according to the embodiment of the present invention is released.

A hybrid vehicle according to an embodiment of the present invention will be specifically described with reference to FIG. The hybrid vehicle shown in FIG. 1 includes an engine 1, a first electric motor 5, and a second electric motor 6 as power sources, and an output shaft 2 of the engine 1 and a first electric motor 5 are connected to a power split mechanism 4. ing. The drive shaft 3 connected to the power split mechanism 4 is connected to the rotor 6 a of the second electric motor 6 via the speed change unit 8.

The power split mechanism 4 is a mechanism that distributes the torque of the engine 1 to the first electric motor 5 and the drive shaft 3, and is configured to generate a differential action. Specifically, the engine 1 is connected to the first rotating element and the first electric motor 5 is connected to the second rotating element of the four rotating elements that are provided with a plurality of sets of differential mechanisms and generate a differential action. The drive shaft 3 is connected to the third rotating element, and the brake mechanism 7 is connected to the fourth rotating element.

The power split mechanism 4 is configured by combining two planetary gear mechanisms. The first planetary gear mechanism is a single-pinion type planetary gear mechanism and includes a sun gear S1, a carrier C1, and a ring gear R1. The second planetary gear mechanism is a double pinion type planetary gear mechanism and includes a sun gear S2, a carrier C2, and a ring gear R2. The first planetary gear mechanism corresponds to the first differential mechanism in the embodiment of the present invention, and the second planetary gear mechanism corresponds to the second differential mechanism in the embodiment of the present invention.

The output shaft 2 of the engine 1 is connected to the carrier C1 of the first planetary gear mechanism, and the carrier C1 and the ring gear R2 of the second planetary gear mechanism are connected to each other and are configured as a first rotating element. The rotor 5a of the first electric motor 5 is connected to the sun gear S1 of the first planetary gear mechanism and is configured as a second rotating element. The drive shaft 3 is connected to the ring gear R1 of the first planetary gear mechanism, and the ring gear R1 and the carrier C2 of the second planetary gear mechanism are connected to each other and are configured as a third rotating element.

The brake mechanism 7 is connected to the sun gear S2 of the second planetary gear mechanism via the rotating shaft 7a, and is configured as a fourth rotating element. The brake mechanism 7 can suppress the rotation of the rotating shaft 7a. That is, the rotation of the fourth rotating element can be suppressed.

The first electric motor 5 mainly generates electric power by rotating by receiving torque from the engine 1, and a reaction force of the torque due to the electric power acts on the drive wheels. By controlling the rotation speed of the first electric motor 5, the rotation speed of the engine 1 continuously changes. Further, the first electric motor 5 can exchange electric power with an inverter (not shown).

The second electric motor 6 is a device that assists the driving force or the braking force. When assisting the driving force, the second electric motor 6 receives power supply and functions as an electric motor. On the other hand, when assisting the braking force, the second electric motor 6 functions as a generator that is rotated by the torque transmitted from the drive wheels (not shown) to generate electric power. Further, the second electric motor 6 can exchange electric power with an inverter (not shown).

The brake mechanism 7 is composed of a friction clutch or the like capable of frictionally engaging the rotating shaft 7a with a fixed member such as a case (not shown). Moreover, the brake mechanism 7 is configured so that the engagement pressure can be adjusted by a hydraulic actuator. By frictionally engaging the rotating shaft 7a and a fixing member such as a case (not shown), it is possible to output a braking torque that suppresses the rotation of the second rotating element.

In the state where the rotation of the fourth rotating element is not suppressed by disengaging the brake mechanism 7, the HV traveling mode in which the vehicle travels at least by the power of the engine 1 is realized. The definition of the HV traveling mode will be described later. On the other hand, in the state where the rotation of the fourth rotating element is suppressed to 0 rotation by putting the brake mechanism 7 in the engaged state, the gear ratio determined by the power split mechanism 4 is overdrive (hereinafter, abbreviated as OD). ) State, and the OD mode is realized.

An ECU (Electronic Control Unit) 9 can control each by transmitting and receiving control signals to and from the engine 1, the first electric motor 5, the second electric motor 6, and the brake mechanism 7. For example, the ECU 9 detects the accelerator opening and obtains the required driving force based on a control signal from an accelerator pedal (not shown), and controls the output torque of the engine 1, the first electric motor 5, and the second electric motor 6. Further, by transmitting a control signal to the brake mechanism 7 based on the required driving force and the vehicle speed, it is possible to switch between the HV traveling mode and the OD mode described above.

The ECU 9 can further calculate the current drive wheel speed, that is, the rotation speed of the drive shaft 3 based on a signal from a drive wheel speed sensor (not shown). Further, the longitudinal acceleration G of the hybrid vehicle can be calculated from the signal from the longitudinal acceleration sensor (not shown). Based on these driving wheel speeds and longitudinal acceleration G, it is possible to determine whether or not the hybrid vehicle is in a slip state.

Next, the concept and collinear diagram of the control according to the embodiment of the present invention will be described with reference to FIGS. 2 and 3 to 6. FIG. 2 is executed in a state in which the hybrid vehicle according to the embodiment of the present invention is running or in a ready-on state in which the control system is activated.

First, the ECU 9 determines whether the hybrid vehicle is traveling in the HV traveling mode in which the brake mechanism 7 is disengaged (Step 1). When the vehicle is traveling in the HV traveling mode, that is, when the determination in Step 1 is affirmative, the process proceeds to Step 2. On the other hand, if the determination is negative in Step 1, the process proceeds to return, and then returns to the start again.

FIG. 3 shows the number of rotations in the vertical direction and the sun gear S1 of the first planetary gear mechanism, the sun gear S2 of the second planetary gear mechanism, the carrier C1 of the first planetary gear mechanism, and the second planetary gear in order from the left. FIG. 8 is a collinear diagram showing four rotating elements of a ring gear R2 of the mechanism, a ring gear R1 of the first planetary gear mechanism, and a carrier C2 of the second planetary gear mechanism. Specifically, the upper side of the straight line O indicating that the rotation speed is 0 corresponds to the rotation direction of the engine 1, that is, the positive rotation, and the lower side corresponds to the negative rotation. Note that the definition of the alignment chart as described above is the same for the other alignment charts (FIGS. 4 to 6), and therefore the description thereof will be omitted below.

A straight line 101 in FIG. 3 shows an example of an alignment chart in the case of traveling in the HV traveling mode. The HV traveling mode is specifically a case where the brake mechanism 7 is disengaged as described above, and represents a state in which the sun gear S2 of the second planetary gear mechanism is negatively rotating.

Next, in Step 2, the ECU 9 calculates the slip speed based on the current drive wheel speed and the longitudinal acceleration G in order to determine whether or not the drive wheels are slipping due to the hybrid vehicle traveling on a low μ road or the like. .. After calculating the slip speed, the process proceeds to Step 3. The slip speed can be calculated by subtracting the estimated vehicle speed B obtained by integrating the longitudinal acceleration G from the estimated vehicle speed A calculated from the driving wheel speed. As long as the drive wheels are not slipping, the estimated vehicle speeds are substantially the same. On the other hand, if the drive wheels are slipping, the rotational speed of the drive wheels will be high, and there will be a gap in each estimated vehicle speed. That is, it can be determined that when the slip speed is substantially 0, the slipping state is not present, while when the slip speed is a positive value, the slipping state is present.

Next, in Step 3, it is determined whether or not the hybrid vehicle is in a slip state based on the slip speed obtained in Step 2. As described above, when the slip speed is a positive value, the slip state is positively determined in Step 3, and the process proceeds to Step 4. On the other hand, when the slip speed is a value of substantially 0, the negative determination is made in Step 3 that the vehicle is not in the slip state, and the process proceeds to Step 5.

Here, an example of a state in which the hybrid vehicle is slipping will be described with reference to FIG. The straight line 202 in FIG. 4 indicates the state of the straight line 101 in FIG. When the hybrid vehicle is traveling on the straight line 202 when the vehicle slips, the rotational speeds of the drive wheels rapidly increase, so that the rotational speeds of the ring gear R1 and the carrier C2, which are the third rotating elements, rapidly increase. The straight line 201 shows the state at this time. The rotation speed of the third rotating element increases, and the rotation speeds of the carrier C1 and the ring gear R2 to which the engine 1 is coupled do not change because the output torque of the engine 1 is constant. Therefore, the rotation speeds of the sun gear S1 and the sun gear S2 increase in the negative rotation direction.

Next, in Step 4, since it is determined in Step 3 that the hybrid vehicle is in the slipping state, the braking mechanism 7 is instructed to return from the slipping state, and the engaging pressure of the braking mechanism 7 is gradually increased. The rotation of the fourth rotating element is suppressed.

Here, an example of the case where the brake mechanism 7 is engaged in Step 4 will be described with reference to FIG. A straight line 301 in FIG. 5 shows the state of the straight line 201 in FIG. By engaging the brake mechanism 7 from the state of the straight line 301, a braking torque is applied to the sun gear S2 that is the fourth rotating element, so that the rotation is suppressed. Further, the rotation speeds of the carrier C1 and the ring gear R2 to which the engine 1 is connected do not change because the output torque of the engine 1 is constant. Therefore, the absolute value of the rotation speed of the ring gear R1 and the carrier C2 decreases due to the rotation of the sun gear S2 being suppressed and approaching 0 rotation. By doing so, the state of the straight line 302 is obtained. After increasing the engagement pressure of the brake mechanism 7, the process returns to Step 2.

As described above, the absolute value of the rotation speed of the ring gear R1 and the carrier C2 is reduced by engaging the brake mechanism 7 with the rotation speed of the engine 1 unchanged. Along with this, it is possible to secure the blip force of the tire provided on the drive wheels connected to the ring gear R1 and the carrier C2. Therefore, it is possible to recover from the slip state. Further, by performing the control in this way, the control can be executed regardless of the state of the power source such as the engine or the electric motor. Therefore, it is possible to suppress the delay in the return from the slip due to the fact that the control for returning from the slip cannot be appropriately performed depending on the state of the power source.

Next, in Step 5, it is determined whether or not the brake mechanism 7 is in the engaged state. Here, the case where the brake mechanism 7 is in the engaged state is the case where the determination is negative in Step 3 after returning to Step 2 via Step 4. If the determination in step 5 is affirmative, it is determined in step 3 that the brake mechanism 7 is not in the slip state, and the brake mechanism 7 does not need to be in the engaged state. To do. After that, it becomes a return. On the other hand, if the determination in Step 5 is negative, the process returns.

Here, an example of the case where the brake mechanism 7 is brought into the non-engaged state after returning from the slip state will be described with reference to FIG. A straight line 401 in FIG. 6 indicates the state of the straight line 302 in FIG. When the brake mechanism 7 is disengaged from the state of the straight line 401, the torque of the first electric motor 5 and the torque of the second electric motor 6 are accelerated again to return to the HV traveling mode. It becomes a state.

In the above-described embodiment, the engagement pressure of the brake mechanism 7 is increased regardless of the magnitude of the slip speed value. However, when the slip speed value is large, the torque that suppresses the rotation of the third rotating element is set to If it is not made large, problems such as long recovery time will occur. Therefore, the larger the value of the slip speed, the larger the engagement pressure of the brake mechanism 7 and the larger the braking torque. By doing so, it is possible to recover from the slip state.

In the above-described embodiment, the longitudinal acceleration sensor is used to determine whether or not the vehicle is in the slip state, but the present invention is not limited to this. For example, the wheel speeds before and after the slip may be measured, and the determination may be made based on the abrupt change in the value.

In the above-described embodiment, the carrier C1 of the first planetary gear mechanism has the output shaft 2 of the engine 1, the sun gear S1 has the rotor 5a of the first electric motor 5, the ring gear R1 has the drive shaft 3, and the sun gear S2 of the second planetary gear mechanism. The brake mechanism 7 is connected to the rotary shaft 7a via the rotary shaft 7a, but is not limited to this. For example, the carrier C1 of the first planetary gear mechanism and the carrier C2 of the second planetary gear mechanism are used as the output shaft 2 of the engine 1, the sun gear S1 and the sun gear S2 as the first electric motor 5, the ring gear R1 as the drive shaft 3, and the ring gear R2. The brake mechanism 7 may be connected via the rotating shaft 7a.

In the above-described embodiment, the hydraulic actuator is used to engage the brake mechanism 7, but an electric actuator may be used.

DESCRIPTION OF SYMBOLS 1... Engine, 2... Output shaft, 3... Drive shaft, 4... Power split mechanism, 5... 1st electric motor, 5a... Rotor, 6... 2nd electric motor, 6a... Rotor, 7... Brake mechanism, 7a... Rotation shaft, 8... Transmission unit, 9... ECU.

Claims (2)

Engine, electric motor, drive wheels, brake mechanism,
A first differential mechanism including a first rotating element connected to the engine, a second rotating element connected to the electric motor, and a third rotating element connected to the drive wheel;
A second differential mechanism having at least a fourth rotating element to which the brake mechanism is coupled;
A controller that controls the engine, the electric motor, and the brake mechanism;
The brake mechanism can output a braking torque that suppresses the rotation of the fourth rotating element, and fixes the second rotating element at 0 rotation when the rotation speed of the first rotating element is set to a predetermined value. The rotation speed of the third rotating element when the rotation of the fourth rotating element is suppressed to 0 rotation by the brake mechanism rather than the rotation speed of the third rotating element at that time, is configured to be accelerated. In a hybrid vehicle drive control system,
The controller is
A hybrid vehicle configured to output a braking torque by the brake mechanism when the drive wheel slips and the fourth rotating element rotates in a direction opposite to the first rotating element. Drive control system.
The drive control system for a hybrid vehicle according to claim 1,
The controller is
The slip amount of the drive wheel can be detected,
A drive control system for a hybrid vehicle, wherein the braking torque output from the brake mechanism is increased as the slip amount increases.

Images