JP3802001B2 - Shift control device for hybrid vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a shift control device for a hybrid vehicle.
[0002]
[Prior art]
Conventionally, as a shift control device of this type of hybrid vehicle, a device disclosed in Patent Document 1 detects an excessive driving force acting on a wheel from an engine, and controls an output of a motor so as to suppress the excessive driving force. Control and avoid wheel slip.
[0003]
This hybrid vehicle is provided with a belt-type continuously variable transmission, and the engine clutch is not disengaged even during a shift operation, so that it is possible to avoid loss of driving force on the wheels.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-241624
[Problems to be solved by the invention]
By the way, in the case of a hybrid vehicle including a gear-type transmission that changes gear ratios by switching gears, it is necessary to disconnect engine power via an engine clutch during a shift operation.
[0006]
However, during slip traveling where the drive wheel slides on a low μ road such as a frozen road, if the engine clutch is disengaged when the transmission shift operation is performed, the driving force transmitted to the wheel during that time is lost. Since the slip is settled, after switching to the gear position on the high speed side once, the controller gives a command to switch to the gear position on the low speed side in response to the decrease in the wheel speed, so it is returned to the original gear position. There is a possibility that this shifting operation is repeated.
[0007]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a shift control device for a hybrid vehicle that can prevent repeated shift operation during slip traveling.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a transmission that changes a gear ratio between an input shaft and an output shaft by switching gears that transmit power to a wheel drive system, an engine clutch that connects and disconnects an engine output shaft and a transmission input shaft, The present invention is applied to a shift control device for a hybrid vehicle including a motor that transmits power to a drive system.
[0009]
A shift operation time determining means for determining a shift operation time in which a shift operation is performed in which the engine clutch is disengaged and the gear of the transmission is switched;
Output control means for maintaining the power transmitted to the drive system of the wheels by driving the motor during shifting operation ;
A slip travel time judging means for judging the slip travel time of the hybrid vehicle based on the speed difference between the drive wheel and the driven wheel,
The output control means is configured to control the output of the motor so as to maintain the target slip ratio during the slip traveling .
[0011]
Operation and effect of the invention
In the first aspect of the invention, the engine clutch is disconnected for several seconds, for example, when the transmission shift operation is performed during slip traveling. During this period, the driving force is transmitted from the motor to the rear wheels, so the engine clutch is disconnected. However, the loss of the driving force of the wheels can be avoided, and the repeated shifting operation can be prevented during slip traveling.
[0012]
By controlling the output of the motor so as to maintain the target slip ratio even while the engine clutch is disengaged , it is possible to perform a shift operation while maintaining the driving force of the wheels.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0014]
As shown in FIG. 1, the power train of the vehicle includes an engine 1, an engine clutch 3, and a transmission 4, and the output of the engine 1 is transmitted to the input shaft of the transmission 4 via the engine clutch 3. Is transmitted from the propeller shaft to the left and right rear wheels (drive wheels) 7 through the differential gear 5 and the drive shaft.
[0015]
The engine 1 combusts the supplied fuel in a cylinder, and rotates its output shaft through a piston that reciprocates in the cylinder. The engine control unit 10 controls the fuel supply amount in accordance with a detection signal from the engine rotation sensor 11 and a request information signal from the vehicle control unit 20 described later, and adjusts the generated output of the engine 1.
[0016]
The engine clutch 3 connects and disconnects the output shaft of the engine 1 and the input shaft of the transmission 4 via a clutch booster 8. The clutch booster 8 disconnects the engine clutch 3 by pressurized air guided from a pneumatic pressure source, and connects the engine clutch 3 by atmospheric pressure guided from a clutch valve 19 (see FIG. 2).
[0017]
Further, the vehicle power train includes a motor 2, a motor clutch 12, and a power transmission mechanism 13, and the rotation of the motor 2 is transmitted to the input shaft of the transmission 4 via the motor clutch 12 and the power transmission mechanism 13.
[0018]
The transmission 4 changes the gear ratio between the input shaft and the output shaft by switching the gear that transmits power to the wheel drive system. For this reason, it is necessary to disconnect the engine power via the engine clutch 3 at the time of shifting operation.
[0019]
The motor 2 is an AC machine such as a three-phase synchronous motor or a three-phase induction motor, and is driven by an inverter 15. The inverter 15 is connected to an electric double layer capacitor (storage element) 16, converts the DC charging power of the capacitor 16 into AC power and supplies it to the motor 2, and converts the AC generated power of the motor 2 into DC power to convert the capacitor 16 is charged.
[0020]
The storage element is not limited to the capacitor 16, and various storage batteries using chemical reactions may be used. Further, the motor 2 is not limited to an AC machine and may be driven by a DC / DC converter using a DC motor.
[0021]
The vehicle control unit 20 includes information from the engine control unit 10 and the inverter 15, an accelerator opening sensor 22, a stroke sensor 24 of the engine clutch 3, a gear position sensor 23 of the transmission 4, a rear wheel speed sensor 25, a front wheel speed sensor. 26, and the like, and according to the driving conditions based on these signals, the connection / disconnection of the engine clutch 3, the connection / disconnection of the motor clutch 12, the output of the engine 1 and the output of the motor 2 are controlled in a coordinated manner. .
[0022]
The vehicle control unit 20 determines when the rear wheel 7 slips when traveling on a low μ road such as a frozen road, for example, and outputs the output of the engine 1 so that the actual slip ratio approaches the target slip ratio. The operation of the engine clutch 3 and the transmission 4 and the output of the motor 2 are controlled in a coordinated manner.
[0023]
FIG. 2 is a control block diagram showing the configuration of the vehicle control unit 20. The detection signals of the rear wheel speed sensor 25 and the front wheel speed sensor 26 are input after being processed through the detection means 31 and 32.
[0024]
The slip determination means 33 determines the slip traveling time when the rear wheel 7 slips based on the speed difference between the rear wheel 7 and the front wheel 6. Then, the output of the engine 1 is calculated so that the detected slip ratio approaches the target value, and information is transmitted / received from the engine output control means 35 to the engine control unit (engine control means) 10 via the communication line. The output of the engine 1 is controlled by the control unit 10.
[0025]
The timing chart of FIG. 3 shows an example of output control of the engine 1 performed by the engine control unit 10 during slip traveling. During slip traveling, the wheel speed of the rear wheel 7 is higher than the speed of the front wheel 6, but the engine required torque value is set according to the actual slip ratio regardless of the accelerator opening so as to keep this wheel speed difference constant. Control.
[0026]
The vehicle control unit 20 performs the shift control of the transmission 4 so that the detected slip ratio approaches the target value as the vehicle speed increases or decreases. For this reason, the vehicle control unit 20 sends a control signal from the gear shift control means 36 to the transmission control means 37 based on a command from the slip determination means 33. The transmission control means 37 controls the speed change operation of the transmission 4.
[0027]
The vehicle control unit 20 performs control to connect and disconnect the engine clutch 3 in response to the transmission operation of the transmission 4 being performed. For this reason, the vehicle control unit 20 sends a control signal to the clutch valve 19 by the engine clutch control means 41 and the engine clutch closing means 42 based on a command from the slip determination means 33, and the engine before the transmission operation of the transmission 4 is performed. The clutch 3 is disconnected and the clutch control for connecting the engine clutch 3 is performed after the shift operation is performed.
[0028]
However, if the engine clutch 3 is disengaged for several seconds, for example, when the speed change operation of the transmission 4 is performed during slip traveling, the driving force transmitted to the rear wheel 7 is lost during that time, so the wheel speed of the rear wheel 7 decreases. And slip fits. For this reason, after the gear position is once switched to the high-speed side gear position, the gear shift control means 36 issues a command to switch to the low-speed side gear position in response to the reduction of the wheel speed of the rear wheel 7 to return to the original gear position. There is a possibility that hunting may be caused by repeating this shifting operation.
[0029]
Therefore, as the gist of the present invention, the vehicle control unit 20 drives the motor 2 to maintain the target slip ratio while the engine clutch 3 is disengaged and the transmission operation of the transmission 4 is performed. 2 and the rotational speed of the input shaft of the transmission 4 are controlled so that the operation of switching the gears of the transmission 4 is performed smoothly. That is, the rotational speed control is performed during the shifting operation (until the gear is determined), and the torque control is performed after the gear is determined.
[0030]
Therefore, the vehicle control unit 20 transmits / receives information to / from the inverter (motor control means) 15 via the communication line from the motor output control means 38 based on a command from the slip determination means 33, and the inverter 15 Output control is performed.
[0031]
As a result, when the shift operation of the transmission 4 is performed during slip traveling, the engine clutch 3 is disconnected, for example, for several seconds. During this time, the driving force of the rear wheels 7 is not lost, and it is possible to prevent hunting that repeats shifting operation during slip traveling. At this time, by controlling the output of the motor 2 so as to maintain the target slip ratio even while the engine clutch 3 is disconnected, the shift operation can be performed while maintaining the driving force of the wheels.
[0032]
The flowchart of FIG. 4 shows a routine for performing a shift process during slip traveling, and is executed in the vehicle control unit 20 at regular intervals.
[0033]
Explaining this, it is determined in step 1 whether or not a shift operation has been performed. When the shift operation has been performed, the routine proceeds to step 2 where the engine clutch 3 is disconnected. The processing performed in step 1 corresponds to a shift operation time determination means.
[0034]
Subsequently, the process proceeds to steps 3 and 4 to read the wheel speeds detected by the front wheel speed sensor 26 and the rear wheel speed sensor 25, and the wheel speed of the rear wheel 7 is higher than the speed of the front wheel 6 in step 5. It is determined whether or not it is during slip traveling. The processing performed in step 1 corresponds to the slip travel time determination means.
[0035]
If it is determined that the vehicle is in the normal travel mode instead of the slip travel mode, the process proceeds to Steps 6 to 7 to perform the shift control process, determine the transmission gear, and perform the engine clutch 3 connection process.
[0036]
On the other hand, if it is determined that the vehicle is in slip traveling, the process proceeds to step 9 to start control during slip traveling, and a shift control process is performed in step 10.
[0037]
In the following step 11, the engine torque request value from the engine output control means (ASR) 35 is read.
[0038]
In the following step 12, the motor torque value output to the motor 2 from the engine torque request value is calculated as motor torque value = engine torque request value / gear ratio × correction coefficient. The processing performed in steps 11 and 12 corresponds to output control means.
[0039]
In subsequent steps 13 to 14, the transmission gear is determined, the motor torque value is output to the motor 2, and the engine clutch 3 is connected. Then, at step 16, the control at the time of slip traveling is terminated.
[0040]
The rotation of the motor may be transmitted to the output shaft of the transmission. In this case, part of the driving force of the motor is transmitted to the gear of the transmission during the operation of switching the gear of the transmission, but the operation of switching the gear can be performed more smoothly.
[0041]
The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of the control device.
FIG. 3 is a timing chart showing engine control details.
FIG. 4 is a flowchart showing the contents of control during gear shifting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Motor 3 Engine clutch 4 Transmission 6 Front wheel 7 Rear wheel 13 Power transmission mechanism 15 Inverter 16 Capacitor 20 Vehicle control unit 25 Rear wheel speed sensor 26 Front wheel speed sensor

Claims (1)

A transmission that changes the gear ratio between the input shaft and the output shaft by switching the gear that transmits power to the drive system of the wheels;
An engine clutch that connects and disconnects the engine output shaft and the transmission input shaft;
In a shift control device for a hybrid vehicle comprising a motor that transmits power to a wheel drive system,
A shift operation time determination means for determining a shift operation time in which a shift operation is performed in which the engine clutch is disengaged and the gear of the transmission is switched;
Output control means for maintaining the power transmitted to the drive system of the wheels by driving the motor during the shift operation ;
A slip travel time judging means for judging the slip travel time of the hybrid vehicle based on the speed difference between the drive wheel and the driven wheel,
The shift control apparatus for a hybrid vehicle, wherein the output control means controls the output of the motor so as to maintain the target slip ratio during the slip traveling .

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