JP2004316736A - Variable speed-controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable speed-controller of a vehicle capable of reducing speed change shock by eliminating a step in torque before and after speed change caused in gear shifting. <P>SOLUTION: In this variable speed-controller of the vehicle, the step in torque in gear shift is reduced by lowering the rotational speed of an engine before gear shifting, and the torque becoming insufficient by the lowering of the rotational speed of the engine is supplemented by a motor. By this, gear shift shock can be prevented and a driver does not almost cause uncomfortable feeling resulting from the gear shift shock. Also, before the gear shifting, the engine rotational speed is maintained at a specified rotational speed to operate the motor by a power generated by a generator while lowering the use amount of a high-voltage battery. By this, a drive torque becoming insufficient in shift-up operation is supplemented. Accordingly, the capacity of the high-voltage battery can be remarkably lowered while reducing consumed fuel. As a result, uncomfortable feeding given to the driver can be minimized by effectively lowering gear shift shock occurring in the shift-up operation in the same manner as indicated above. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a shift control device for a vehicle that reduces shift shock generated during shifting.
[0002]
[Prior art]
In a vehicle equipped with an electronic control type automatic transmission (ECT), it is known that the driving torque temporarily changes suddenly with a shift, for example, during a shift-up operation from a low gear to a high gear. (This is also called “torque step”). For this reason, in a vehicle equipped with ECT, there is a problem that a shift shock occurs due to the torque step at the time of a shift-up operation or the like, giving a feeling of strangeness to the driver.
[0003]
As a method for solving such a problem, there is known a vehicular drive device that reduces the shift shock generated at the time of a shift by applying an assist torque from a motor generator to the drive torque of the vehicle after the shift is completed, based on a determination of the shift end. (For example, see Patent Document 1).
[0004]
Also, there is known a shift control device for a hybrid vehicle that performs a regenerative operation by an electric motor or the like before shifting to reduce the input rotation speed of the transmission to prevent a shift shock occurring during shifting (for example, Patent Document 2). reference).
[0005]
There is known a four-wheel drive system in which a front wheel is driven by an engine and a rear wheel is driven by a motor (for example, see Patent Document 3).
[0006]
[Patent Document 1]
JP-A-10-243502
[Patent Document 2]
JP 2000-2327 A
[Patent Document 3]
JP-A-7-231508
[0007]
[Problems to be solved by the invention]
However, even if the shift shock generated at the time of shifting is reduced by applying the assist torque from the motor generator after the shift is completed, the shifting shock at the time of shifting cannot be reduced. For this reason, in order to perform a shift operation without giving the driver an uncomfortable feeling, it is necessary to effectively reduce the shift shock generated at the time of shifting.
[0008]
Further, even if the shift shock is prevented by lowering the input rotation speed to the transmission before shifting, the regenerative operation by the electric motor or the like is performed after the shift instruction is issued, and the input rotation speed is reduced to reduce the speed. If it takes a considerable amount of time to approximate the subsequent synchronous rotation speed, there is a problem that the timing of the shift execution is delayed.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to provide a vehicle shift control device that eliminates a torque step before and after a shift that occurs during a shift and reduces a shift shock.
[0010]
[Means for Solving the Problems]
According to one aspect of the present invention, a shift control device for a vehicle includes: a determination unit configured to determine whether a predetermined shift condition is satisfied; and reducing a rotation speed of the internal combustion engine when the shift condition is satisfied. A driving force adjusting unit that adjusts the driving force of the internal combustion engine by applying a driving force to an output shaft of the internal combustion engine; and a transmission unit that executes a shift after adjusting the driving force.
[0011]
According to the above-described vehicle shift control device, the shift is executed when a predetermined shift condition is satisfied. Here, the shift condition can be determined, for example, based on states such as an accelerator opening and a vehicle speed that are linked to the amount of depression of an accelerator pedal. Further, the shifting includes both upshifting and downshifting.
[0012]
When it is determined that the shift condition is satisfied, the shift control device of the vehicle first reduces the rotational speed of the internal combustion engine (engine), reduces the torque step at the time of shifting, and reduces shift shock. In addition, a driving force is applied to the output shaft of the engine as the engine speed decreases. The drive force (drive torque) acting on the output shaft of the engine is reduced by reducing the engine speed. For this reason, by providing a driving force to the output shaft of the engine, the insufficient driving torque for the decrease is supplemented. Thus, it is possible to effectively reduce a shift shock caused by a decrease in the driving torque during the shift (including before and after the shift). Therefore, a smooth shifting operation can be performed.
[0013]
In one aspect of the shift control device for a vehicle, the driving force adjusting unit increases the rotation speed of the internal combustion engine after the shift and decreases the driving force applied to an output shaft of the internal combustion engine.
[0014]
According to this aspect, it is possible to reduce the driving torque applied to the output shaft of the engine while increasing the rotation speed of the engine after the shift. This makes it possible to smoothly shift to the running state of the vehicle using only the driving torque applied from the engine. Therefore, it is possible to prevent the occurrence of a shift shock even after the shift, and the driver can travel comfortably without feeling uncomfortable.
[0015]
In another aspect of the vehicle shift control device, the vehicle further includes a generator, and the driving force adjusting unit controls the internal combustion engine to a predetermined rotation speed to generate power using the generator.
[0016]
According to this aspect, the engine speed can be controlled to a predetermined speed by performing duty control on a lock-up clutch and the like provided inside the shift control device. By controlling the engine rotation speed to a predetermined rotation speed, for example, 800 to 900 (rpm), it is possible to generate power up to the maximum power amount of the generator in terms of good engine efficiency.
[0017]
In another aspect of the shift control device for a vehicle, the driving force adjusting unit applies a driving force to an output shaft of the internal combustion engine by an electric motor, and drives the electric motor by electric power obtained by the generator.
[0018]
According to this aspect, power supply to the electric motor can be performed through the generator. Therefore, the electric motor can be driven only by the electric power supply from the generator without requiring a power supply device or the like for supplying the electric power to the electric motor. Further, a driving torque obtained by driving the electric motor can be applied to an output shaft of the engine. For this reason, the decrease in the drive torque that occurs during the shift (including before and after the shift) can be supplemented by the drive torque from the electric motor. Therefore, the shift shock generated during the shift can be effectively reduced, and the driver can travel comfortably without feeling uncomfortable.
[0019]
In another aspect of the vehicle shift control device, the predetermined rotation speed may be a rotation speed at which the power generation efficiency of the generator is maximum and the fuel consumption rate of the internal combustion engine is minimum. . This makes it possible to drive the motor using the power generated efficiently by the generator, and it is not necessary to use the power stored in a battery or the like for driving the motor.
[0020]
In another aspect of the shift control device for a vehicle, the shift means is started after a predetermined time estimated based on an accelerator pedal depression amount and a vehicle acceleration. According to this aspect, the shift start time can be estimated based on the values of the vehicle acceleration and the accelerator pedal operation amount. Thus, the shifting means can start shifting after a predetermined time that is the estimated value of the calculated shift start time.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0022]
[Vehicle configuration]
First, a schematic configuration of a vehicle including a shift control device according to the present invention will be described. The vehicle 100 described below is one in which the shift control device according to the present invention is applied to a 4WD (four-wheel drive) FR vehicle (front-wheel drive system with an engine installed). However, the application of the present invention is not limited to this, and is also applicable to general FR vehicles and FF vehicles (engine front-wheel drive system). Further, since the present vehicle is based on a known 4WD specification FR vehicle, description of 4WD is omitted.
[0023]
FIG. 1 shows a system configuration of a vehicle 100 including a shift control device according to the present invention.
[0024]
As shown in FIG. 1, the vehicle 100 includes an engine 1, a generator 2, a belt 3, an inverter 4, a high-voltage battery 5, a 12V battery 16, a DC / DC converter 17, a front-wheel drive unit 6, , An automatic transmission 7, a hydraulic control device 8, a propeller shaft 9, a rear wheel drive unit 10, and an ECU 15. Hereinafter, each component will be described with reference to FIG.
[0025]
The engine 1 is an internal combustion engine that generates power by exploding an air-fuel mixture in a combustion chamber. The reciprocating motion of the piston due to the combustion of the air-fuel mixture in the combustion chamber is converted into a rotational motion of a crankshaft (not shown) via a connecting rod (not shown). The crankshaft transmits power to the rear wheel drive unit 10 via the automatic transmission 7.
[0026]
Apart from such a power transmission system, one end of the crankshaft is connected to a crankshaft pulley (not shown). The power of the crankshaft pulley can be transmitted to and from the pulley provided on the generator 2 by the belt 3.
[0027]
The generator 2 includes a permanent magnet type synchronous motor or the like, and is provided in an engine room. The generator 2 generates power based on the power generated by the engine 1. The generator 2 is connected to the inverter 4 through a power cable (not shown). Therefore, the electric power generated by the generator 2 is supplied to the inverter 4 through the power cable.
[0028]
The inverter 4 is a device that mainly controls the amount of generated power, and is connected to the generator 2, the motors 6a and 6b, the high-voltage battery 5, and the 12V battery 16 via a power cable (not shown). When receiving the power supply from the generator 2, the inverter 4 converts the power to a predetermined voltage based on a command signal from the ECU 15. The inverter 4 supplies electric power (dashed arrow 30) to the electric motors 6a and 6b provided on the left and right sides of the front wheel, and controls the driving or stopping of the electric motors. Therefore, the inverter 4 can transmit or cut off power to the front wheel drive unit 6 by controlling the electric motors 6a and 6b based on the command signal from the ECU 15. The operation of the electric motors 6a and 6b to drive the front wheel drive unit 6 is referred to as "assist" by the electric motors 6a and 6b. In addition, when receiving the power generated by the generator 2, the inverter 4 converts the power into a DC voltage suitable for charging the high-voltage battery 5 and the 12-V battery 16, and The 12V battery 16 can be charged (hereinafter, also referred to as “regeneration”). The electric motors 6a and 6b may have an electromagnetic clutch. In this case, the clutch control is performed by the ECU 15, and the load can be reduced when assisting by the electric motors 6a and 6b is not performed during acceleration.
[0029]
The inverter 4 can drive the left and right front wheels independently by controlling the electric motors 6a and 6b. For example, the inverter 4 controls the electric motors 6a and 6b according to the running state of the vehicle 100 to apply a rotational driving force to only one of the left and right front wheels, and to rotationally drive the other one of the wheels. It is possible to block the force. Thereby, the vehicle 100 can obtain power performance according to a traveling state (for example, traveling on an uneven road surface, traveling up a hill, or the like).
[0030]
The high-voltage battery 5 is a secondary battery such as a lead storage battery or a nickel hydride battery. The high-voltage battery 5 supplies power to electric motors 6a and 6b, which will be described later, and operates them. For example, the high-voltage battery 5 can use a high voltage (42 V or more) as a rated voltage in order to smoothly operate two electric motors 6a and 6b described later. On the other hand, the 12V battery 16 can operate auxiliary equipment such as an air conditioner, or supply electric power to electric motors 6a and 6b, which will be described later, and operate them.
[0031]
The DC / DC converter 17 is disposed between the inverter 4 and the 12V battery 16 and charges the 12V battery 16 by transforming the voltage from the inverter 4.
[0032]
The front wheel drive unit 6 includes a speed reducer (not shown), a drive shaft, left and right front wheels, and electric motors 6a and 6b. The speed reducer is a mechanism that mainly adjusts the rotational speed of the left and right front wheels. Specifically, when the vehicle 100 travels on a straight road, the speed reducer rotates the left and right front wheels at the same speed. On the other hand, when the vehicle 100 performs a turning motion, a difference in rotation speed between the left and right front wheels occurs. Therefore, the speed reducer adjusts those rotation speeds to enable a smooth turning motion.
[0033]
The electric motors 6a and 6b are preferably permanent magnet type synchronous motors for converting electric energy into mechanical energy, and are provided at positions for driving the left and right front wheels, respectively. Each of the electric motors 6a and 6b has a rotor (not shown) serving as a rotating shaft and a stator (not shown) for rotating the rotor by a change in a magnetic field. When the electric motors 6a and 6b receive the electric power supply (dashed arrow 30) from the inverter 4, the magnetic field of the stator changes every moment inside the electric motors 6a and 6b, whereby the rotor rotates. For this reason, the electric motors 6a and 6b can perform a rotating operation.
[0034]
A pinion gear provided at one end of each rotor of the electric motors 6a and 6b meshes with an external gear of the speed reducer. Therefore, when the electric motors 6a and 6b are rotationally driven, the drive shaft can be rotated left and right independently, and the left and right front wheels can be driven respectively. Further, the speed reducer has an electromagnetic clutch. For this reason, when the rotational driving force from the electric motors 6a and 6b is unnecessary, the ECU 15 can operate the electromagnetic clutch to cut off the power transmission from the electric motors 6a and 6b to the front wheel drive unit 6. Therefore, the assist by the electric motors 6a and 6b can be appropriately performed according to the state of the vehicle 100.
[0035]
The automatic transmission 7 includes a torque converter 72 and a multi-stage transmission mechanism 71 having a plurality of planetary gears. The torque converter 72 and the multi-stage transmission mechanism 71 are arranged in series.
[0036]
The torque converter 72 is provided between the engine 1 and the multi-stage transmission mechanism 71. The torque converter 72 uses a fluid such as oil to function as a clutch that intermittently transmits the rotational torque output from the engine 1 to the multi-stage transmission mechanism 71, and increases the rotation torque to increase the multi-stage transmission mechanism. 71 to transmit the data to
[0037]
The torque converter 72 according to the present example is a known one, and includes a pump impeller connected to the crankshaft of the engine 1, a turbine impeller connected to the input shaft of the multi-stage transmission mechanism 71, and a one-way clutch. And a lock-up clutch 72a for mechanically connecting the pump impeller side and the turbine impeller side. In the thus configured torque converter 72, the operating oil circulates and flows in the order of pump impeller → turbine impeller → stator → pump impeller by the driving force of the engine 1. Accordingly, the rotation of the turbine impeller can be promoted, and the rotational torque of the input shaft of the multi-stage transmission mechanism 71 can be increased.
[0038]
The lock-up clutch 72a is provided inside the torque converter 72. The lock-up clutch 72a is a clutch that mechanically engages or disengages the pump impeller side and the input shaft of the multi-stage transmission mechanism 71 by the hydraulic control device 8 based on a command signal from the ECU 15. Therefore, by engaging the lock-up clutch 72 a, that is, mechanically engaging the pump impeller with the input shaft of the multi-stage transmission mechanism 71, the rotational torque obtained from the engine 1 is directly used as the input shaft of the multi-stage transmission mechanism 71. Can be transmitted to.
[0039]
That is, even if the above-described torque converter 72 acts as a fluid clutch, power is transmitted through a fluid such as oil, so that an energy loss occurs due to the fluid friction. Therefore, in order to reduce the energy loss, when the rotation speeds of the pump impeller and the turbine impeller become substantially equal to each other, the ECU 15 controls the hydraulic control device 8 to bypass the torque converter 72. , The mechanical engagement between the pump impeller and the input shaft of the multi-stage transmission mechanism 71 is performed. Thereby, the energy loss can be reduced. On the other hand, when the lock-up clutch 72a is released, transmission of the rotational torque obtained from the engine 1 to the input shaft of the multi-stage transmission mechanism 71 can be cut off.
[0040]
Therefore, by engaging or disengaging the lock-up clutch 72a as necessary, the rotational torque of the engine 1 can be transmitted or interrupted to the input shaft of the multi-stage transmission mechanism 71.
[0041]
The multi-stage transmission mechanism 71 is provided between the torque converter 72 and the propeller shaft 9 and has a plurality of gears (planetary gears) corresponding to the five forward speeds (first to fifth speeds) and one reverse speed. ). The multi-stage transmission mechanism 71 operates the hydraulic control device 8 based on a command signal from the ECU 15 to perform a shift operation from a low gear to a high gear (shift up) or a shift operation from a high gear to a low gear (shift). Down).
[0042]
The hydraulic control device 8 is provided near the multi-stage transmission mechanism 71 and mainly includes a solenoid valve and the like. The hydraulic control device 8 controls a multi-stage transmission mechanism 71 by controlling a solenoid valve and the like based on a command signal from the ECU 15. When performing control, the hydraulic control device 8 controls engagement of a lock-up clutch 72a or releases the lock-up clutch 72a by controlling, for example, a solenoid valve operated by hydraulic pressure based on a command signal from the ECU 15. Further, when controlling the multi-stage transmission mechanism 71, the hydraulic control device 8 controls a solenoid valve or the like operated by hydraulic pressure based on a command signal from the ECU 15, for example, to perform a shift operation such as a shift change.
[0043]
The propeller shaft 9 is provided between the automatic transmission 7 and the rear wheel drive unit 10 and the differential, and is a propulsion shaft that transmits drive torque obtained from the engine 1 and the like to the rear wheel drive unit 10.
[0044]
The rear wheel drive unit 10 includes a speed reducer (not shown), a drive shaft, left and right rear wheels, and the like. The speed reducer is a mechanism that adjusts the rotation speed of the left and right rear wheels according to the traveling state of the vehicle 100.
[0045]
The ECU 15 (Engine Control Unit) mainly includes microcomputers such as an input / output device, a storage device, and a central processing unit, and controls the system of the vehicle 100 as a whole. The ECU 15 controls the vehicle 100 in an optimal state based on input information from sensors mounted on the vehicle 100 and the like. Specifically, the ECU 15 calculates the rotation speed of the crankshaft (engine speed 20) from the engine speed sensor, the vehicle speed 21 from the vehicle speed sensor, the depression amount of the accelerator pedal (accelerator opening 22) from the accelerator opening sensor, the acceleration sensor , An acceleration 23 and other signals 24 from the respective sensors are detected.
[0046]
In particular, in the present embodiment, the ECU 15 controls the shift operation of the automatic transmission 7 in accordance with the traveling state of the vehicle 100 (the vehicle speed 21 and the accelerator opening 22), and generates the shift operation when the automatic transmission 7 performs a shift-up operation. In order to prevent a gear shift shock, control such as control of the engine speed 20, assist by the electric motors 6a and 6b, and engagement and release of the lock-up clutch 72a are performed. Here, although the details will be described later, when engaging or disengaging the lock-up clutch 72a, the ECU 15 performs control by appropriately changing the ratio between the ON period and the OFF period (hereinafter referred to as “duty control”). Call).
[0047]
[Shift control]
Next, the shift control according to the present embodiment will be described. In brief, as described above, it is known that a shift shock occurs due to a step in drive torque in a shift operation from a low gear to a high gear (shift up operation) or the like. As a result, the driver feels strange. Therefore, in the present embodiment, two examples will be described in order as a method of preventing the shift shock.
[0048]
Note that the upshift operation refers to a shift operation in which the automatic transmission 7 automatically switches from a low gear to a high gear based on a command signal from the ECU 15. Specifically, the automatic transmission 7 changes the first speed (1st) → the second speed (2nd), the second speed → the third speed (3rd), and the like based on the accelerator opening 22 and the vehicle speed 21. This means shifting from the third speed to the fourth speed (4th) and from the fourth speed to the fifth speed (5th).
[0049]
It should be noted that the step in the drive torque during the upshift operation is basically due to the fact that the drive torque is different for each shift speed (first speed, second speed, etc.). For example, in the case of the shift-up operation from the first speed to the second speed, the drive torque is smaller in the second speed than in the first speed even if the engine speed is almost the same. Will fall sharply. As a result, a step occurs in the driving torque, and a shift shock occurs.
[0050]
(First embodiment)
In the first embodiment, the engine rotational speed is reduced to a predetermined rotational speed (NE3) from the time before the shift to reduce the shift shock, and the output shaft torque of the automatic transmission 7 (hereinafter, simply referred to as “drive torque”). ), The assist torque from the electric motors 6a and 6b is applied, and the insufficient driving torque due to the decrease in the number of revolutions is supplemented.
[0051]
First, a first embodiment will be described with reference to FIGS. 2 (a), (b), (c), (e) and FIG. 2 (c) and 2 (e) show, for convenience of explanation, only the graphs in FIGS. 2 (a) and 2 (b) when performing the shift-up operation from the first speed to the third speed. FIG. 2D is a graph showing the duty (DUTY) control of the lock-up clutch 72a in the second embodiment, and is not used in the first embodiment. In the first embodiment, it is assumed that the lockup clutch 72a is always in the engaged state (the signal is ON).
[0052]
FIG. 2A is a graph showing a relationship between drive torque and time during an upshift operation of the automatic transmission 7. FIG. 2B is a graph corresponding to FIG. 2A and illustrating the relationship between the accelerator opening 22 and time and the relationship between the acceleration 23 of the vehicle 100 and time. FIG. 2C is a graph showing the relationship between the engine speed 20 and time, corresponding to FIGS. 2A and 2B, respectively. FIG. 2E shows the relationship between the drive torque (hereinafter referred to as “assist torque”) of the electric motors 6a and 6b and time corresponding to FIGS. 2A, 2B, and 2C, respectively. It is a graph.
[0053]
In FIG. 2A, the vertical axis represents drive torque, and the horizontal axis represents vehicle speed 21 and time. Here, the driving torque is the output shaft torque of the automatic transmission 7 as described above. In FIG. 2B, the vertical axis indicates the accelerator opening 22 and the acceleration 23, and the horizontal axis indicates time. FIG. 2B shows three types of waveforms W102, W103, and W104, respectively. W102 is a waveform showing the relationship between the accelerator opening 22 and time, W103 is a waveform showing the relationship between the acceleration 23 and time common to the first and second embodiments of the present invention, and W104 is an electric motor. 7 is a waveform showing a relationship between acceleration 23 and time when assist is not performed by the following method.
[0054]
Hereinafter, the shift control according to the present invention will be described. A waveform W102 in FIG. 2B shows a state in which the accelerator pedal opening degree 22 increases with time as a result of the driver continuously depressing the accelerator pedal. When the driver depresses the accelerator pedal, the accelerator opening 22, the vehicle speed 21, and the like increase, and a shift (shift-up) operation is performed when predetermined shift conditions are satisfied.
[0055]
When the upshift from the first speed to the second speed is performed, first, as shown by a waveform W106 in FIG. 2C, the ECU 15 changes the engine speed 20 to the predetermined engine speed when a predetermined condition is satisfied. Lower to several NE3. As described above, by lowering the engine speed prior to the upshifting operation, it is possible to reduce the step of the driving torque during the upshifting operation and reduce the shift shock. However, lowering the engine speed 20 means lowering the driving torque. Accordingly, in conjunction with the engine speed 20 dropping below NE1, the drive torque drops as shown in FIG. 2A (see each hatched portion E1 to E4). Further, due to the drop in the driving torque, the acceleration of the vehicle also drops as shown by a waveform W104 in FIG.
[0056]
Therefore, the ECU 15 operates the electric motors 6a and 6b at the time of the shift-up operation to apply the assist torque from the electric motors 6a and 6b to the driving torque. Thus, the driving torque that is insufficient due to the decrease in the engine speed 20 is supplemented.
[0057]
The state is shown in the graph of FIG. In the graph of FIG. 2E, the vertical axis shows the assist torque by the electric motors 6a and 6b as a waveform W108, and the horizontal axis shows time. As can be seen from this graph, the times when the electric motors 6a and 6b are assisting are approximately from immediately before time t1 to immediately after t3, and from immediately before time t4 to immediately after t6. That is, when a shift operation is expected, the ECU 15 reduces the engine speed to the predetermined speed NE3 and performs assist by the electric motor prior to the shift operation. Thus, the insufficient driving torque is compensated by the electric motor.
[0058]
A change in drive torque when the above-described shift control is performed is shown by a waveform W100 in FIG. In the waveform W100, as compared with the waveform W101 in the case where the assist by the electric motor is not performed, the drive torque gradually decreases during the shift-up operation from the first speed to the second speed and from the second speed to the third speed. Has become. As for the acceleration, as shown by the waveform W103 in FIG. 2B, the drive torque does not drop during the shift-up operation, so that the acceleration 23 is constantly and smoothly changed. Therefore, the driver does not feel a shift shock during the upshift operation.
[0059]
Next, a flowchart of the first embodiment will be described with reference to FIG. This flowchart is executed by the ECU 15 based on signals from various sensors. First, the ECU 15 determines whether a shift condition is satisfied based on output signals from sensors that detect the accelerator opening 22 and the vehicle speed 21 (step S1). When the shift condition is satisfied, the process proceeds to step S2 (step S1; Yes). Here, the provision of the shift condition means that the accelerator opening 22 and the vehicle speed 21 satisfy predetermined conditions.
[0060]
In step S2, prior to the gear shifting operation, the ECU 15 reduces the engine speed 20 to a predetermined speed. That is, the ECU 15 reduces the engine speed 20 from NE1 to NE3 (see the waveform W106 shown in FIG. 2C). Thus, by lowering the engine speed before the gear shifting operation, the step of the driving torque during the gear shifting operation can be reduced, and the gear shift shock can be reduced.
[0061]
Further, the ECU 15 starts assisting by the electric motors 6a and 6b at the same time as lowering the engine speed 20. Thereby, the insufficient driving torque (see E1 to E4 in FIG. 2A) can be supplemented. Therefore, the relationship between the driving torque and the time is W100 shown in FIG. The waveform W100 is a waveform that changes gently with almost no drop in drive torque immediately before the shift-up operation.
[0062]
Next, the ECU 15 performs an upshift operation (step S3). At this time, since the engine speed is reduced immediately before the upshift operation in step S2, there is almost no shift shock during the upshift operation.
[0063]
Next, when the shift-up operation is completed, the ECU 15 gradually increases the engine speed 20 to NE1 and gradually reduces the assist torque by the electric motors 6a and 6b by that amount (step S4). Thus, the vehicle 100 is finally driven only by the driving torque of the engine 1. Here, the reason why the assist torque by the electric motors 6a and 6b is decreased is that the drive torque increases with an increase in the engine speed 20. Therefore, if the assist by the electric motors 6a and 6b is still performed at this time, the drive This is because the torque becomes excessive, causing a shift shock.
[0064]
(Second embodiment)
Next, a second embodiment will be described. In the second embodiment, the engine speed 20 before and after the gear shifting operation is maintained at a predetermined speed by engaging or disengaging (duty control) the lock-up clutch 72a based on the main parts of the first embodiment. The driving torque that is insufficient during the shifting operation is supplemented by the assist torque from the electric motors 6a and 6b.
[0065]
In the first embodiment, the motors 6a and 6b are operated by the power supply from the high-voltage battery 5 at the time of the shift-up operation to supplement the insufficient driving torque. On the other hand, the second embodiment is based on the first embodiment, but uses the electric motors 6a and 6b by supplying power from the generator 2 while reducing the amount of power used in the high-voltage battery 5 during the shift-up operation. To replenish the insufficient drive torque. This point is different from the first embodiment. Therefore, in the case of the second embodiment, by reducing the amount of power used from the high-voltage battery 5, the capacity of the high-voltage battery 5 can be significantly reduced as compared with the first embodiment. There are advantages.
[0066]
A second embodiment will be described with reference to FIGS. 2 (a), (b), (c), (d), (e), FIGS. 4 and 5. The basic contents of the graphs shown in FIGS. 2A, 2B, 2C, and 2E are as described in the first embodiment. FIG. 2D is a graph showing a waveform W107 obtained by duty control on the lock-up clutch 72a. FIG. 4A is a graph showing the power generation characteristics of the generator 2. FIG. 4B is a graph showing the relationship between the engine torque and the engine speed 20.
FIG. 4C is a graph for estimating a shift start time ta at which a first-speed → second-speed shift-up operation starts. FIG. 5 is a flowchart of the shift control according to the second embodiment. In FIG. 2C, a change in the engine speed according to the second embodiment is indicated by a waveform W105.
[0067]
First, when the shift conditions are satisfied, as shown in FIG. 2 (c), at time ta (shift start time) immediately before time t1, the ECU 15 performs a shift-up operation from the first speed to the second speed. The engine speed 20 is maintained at a predetermined engine speed NE2.
[0068]
Here, a method of calculating the shift time estimated value ta will be described with reference to FIG. FIG. 4C is a three-dimensional graph, in which the X-axis shows the vehicle acceleration, the Y-axis shows the accelerator pedal operation amount, and the Z-axis shows the estimated shift time ta. The vehicle acceleration (acceleration 23) on the X axis can be acquired in the ECU 15 by the acceleration sensor. The accelerator pedal operation amount (accelerator opening 22) on the Y axis can be acquired in the ECU 15 by the accelerator opening sensor. Then, the ECU 15 estimates the shift time ta at which the shift-up operation from the first speed to the second speed starts based on the values of the vehicle acceleration and the accelerator pedal operation amount acquired by the acceleration sensor and the accelerator opening sensor.
[0069]
In this embodiment, the shift time ta at which the shift-up operation from the first speed to the second speed starts is estimated based on the values of the vehicle acceleration and the accelerator pedal operation amount. Alternatively, the method of estimating the shift start time ta may be used even in a shift operation other than the first speed to the second speed.
[0070]
A specific example will be described with reference to FIG. 4C. FIG. 4C shows shift time estimated values ta1 to ta4 calculated based on the vehicle acceleration and the accelerator pedal operation amount. When the vehicle acceleration is G1 and the accelerator pedal operation amount is Ac1, the shift time estimated value is calculated as time ta1. When the vehicle acceleration G2 is greater than the vehicle acceleration G1 and the accelerator pedal operation amount is Ac1, the shift time estimated value is calculated as time ta2. When the vehicle acceleration is G1 and the accelerator pedal operation amount Ac2 is larger than the accelerator pedal operation amount Ac1, the shift time estimated value is calculated as time ta3. When the vehicle acceleration is G2 and the accelerator pedal operation amount is Ac2, the shift time estimated value is calculated as time ta4.
[0071]
As can be seen from this graph, the magnitude of the estimated shift time until the start of the first-speed → second-speed shift-up operation is ta3>ta1>ta4> ta2. That is, as the vehicle acceleration increases, the time from the start of the first-speed to the second-speed shift-up operation tends to become shorter. This is due to the fact that the engine speed 20 increases as the vehicle acceleration increases, so that the time until the start of upshifting becomes shorter.
[0072]
Next, after time ta, the ECU 15 performs duty control of ON / OFF of the lock-up clutch 72a. When reaching the time ta, the assist by the electric motors 6a and 6b is started as shown in FIG. As a result, the drive torque that is insufficient due to maintaining the engine speed at NE2 is supplemented. In this way, the insufficient driving torque E1 can be supplemented by the assist torque TR10 from the electric motors 6a and 6b, so that the shift shock generated in the shift-up operation (first speed → second speed) can be reduced. . Thereby, the sense of discomfort given to the driver can be eliminated.
[0073]
After the shift operation is completed, the engine speed 20 is increased again to NE1 from time tc to time t3, as shown in FIG. 2 (c). Immediately after the time tc, the assist torque from the electric motors 6a and 6b is reduced as shown in FIG.
[0074]
Thereafter, from time t3 to time t4, the engine speed 20 is maintained at NE1 as shown in FIG. 2 (c). In addition, from time t3 to time t4, as shown in FIG. 2A, the vehicle 100 is in a state after the upshift operation, that is, a state in which the vehicle 100 is running at the second speed. Further, from time t3 to time t4, as shown in FIG. 2D, the output signal of the lock-up clutch 72a is ON, that is, the engaged state is maintained.
[0075]
Thereafter, every time the shift condition is satisfied, the same shift control is performed as shown in FIG. Also in such a case, the assist torque from the electric motors 6a and 6b is applied, so that the insufficient drive torque generated due to the shift-up operation can be replenished, and the occurrence of the shift shock due to the drop in drive torque can be reduced. Can be prevented. Therefore, the uncomfortable feeling given to the driver can be eliminated.
[0076]
Next, the reason why the engine speed 20 is maintained at NE2 at a higher speed without lowering to NE3 of the conventional example will be described with reference to FIGS. 4 (a) and 4 (b).
[0077]
First, in FIG. 4A, the vertical axis indicates the amount of power generated by the generator 2, and the horizontal axis indicates the engine speed 20. In the figure, a generated power amount of the generator 2 that changes with an increase in the engine speed 20 is shown as a waveform W200. As described above, since the generator 2 is rotatably connected to the crankshaft pulley of the engine 1 via the belt 3, the generator 2 can generate electric power by rotating the engine 1. FIG. 4A is a graph showing the relationship between the engine speed 20 and the amount of power generated by the generator 2 at this time as a waveform W200.
[0078]
In the waveform W200, as the engine speed 20 increases from 0 to NE2, the amount of power generated by the generator 2 also tends to increase. Here, the region where the engine speed 20 is NE0 to NE2 is an idling speed region (reference numeral 200). That is, in this region, the magnitude of the generated power amount of the generator 2 varies depending on the magnitude of the idling rotation speed.
[0079]
Further, in the waveform W200, when the engine speed 20 reaches NE2, the generator 2 has a substantially maximum generated power amount Pmax. That is, if the engine speed 20 is maintained at NE2 or more, the generator 2 has the maximum generated power amount Pmax, and the power is generated most efficiently.
[0080]
On the other hand, setting the engine speed 20 to NE2 has the advantage that the generator 2 can generate up to the maximum generated power amount Pmax with the optimal fuel consumption. This will be described with reference to FIG.
[0081]
FIG. 4B is a graph showing a relationship between the engine speed 20 and the engine torque. As shown in FIG. 4B, the vertical axis indicates the engine torque, and the horizontal axis indicates the engine speed 20. In the figure, a plurality of optimum fuel efficiency lines E100 to E103 are shown. In this example, the engine speed 20 is controlled to change the state from E103 to E102 to E101 to E100. That is, in this example, in particular, by maintaining the engine speed 20 at NE2, the generator 2 can generate power up to the maximum generated power amount Pmax with minimum fuel consumption.
[0082]
As described above, in the second embodiment, as shown in FIG. 2C, during the upshift operation, the engine speed 20 is not reduced to the engine speed NE3 of the first embodiment, but is reduced to the engine speed NE2 higher than that of the first embodiment. To be maintained. This allows the generator 2 to generate power up to the maximum generated power amount Pmax with minimum fuel consumption. That is, power can be generated most efficiently by the generator 2. Thus, in the second embodiment, the electric motors 6a and 6b are operated by the electric power generated by the generator 2 while reducing the amount of electric power used in the high-voltage battery 5 to reduce the driving torque that is insufficient during the upshift operation. Can be replenished. Thus, similarly to the first embodiment, the shift shock generated at the time of the up-shift operation can be effectively reduced, and the uncomfortable feeling given to the driver can be eliminated as much as possible. The amount can be reduced, and the capacity of the high-voltage battery 5 can be reduced.
[0083]
Next, a flowchart of the second embodiment will be described with reference to FIG. This flowchart is executed by the ECU 15 based on signals from various sensors. First, the ECU 15 determines whether a shift condition is satisfied based on output signals from sensors that detect the accelerator opening 22 and the vehicle speed 21 (step S11). When the shift condition is satisfied, the process proceeds to step S12 (step S11; Yes).
[0084]
In step S12, prior to the upshift operation, the ECU 15 maintains the engine speed 20 at a predetermined speed. That is, the ECU 15 reduces the engine speed 20 from NE1 to NE2 and maintains the engine speed 20 at the predetermined speed NE2 (see a waveform W105 shown in FIG. 2C). In addition, the ECU 15 starts assisting by the electric motors 6a and 6b while maintaining the engine speed 20 at the predetermined speed. Further, the ECU 15 starts the duty control of the lock-up clutch 72a.
[0085]
Next, the ECU 15 determines whether the engine speed 20 has reached NE2 by the duty control of the lock-up clutch 72a (step S13). Here, the engine speed 20 (NE2) is, as described above, a speed at which the fuel consumption of the engine 1 can be minimized and the generator 2 can generate power up to the maximum generated power amount Pmax. It is.
[0086]
When the engine speed reaches NE2, the generated power amount of the generator 2 becomes the maximum generated power amount Pmax, and the generator 2 supplies the power to the electric motors 6a and 6b (step S14). This makes it possible to replenish the insufficient driving torque during the upshift operation. When the electric motors 6a and 6b are driven, the amount of power used by the high-voltage battery 5 can be reduced, so that the capacity of the high-voltage battery 5 can be reduced.
[0087]
Further, the relationship between the driving torque and the time at this time is W100 as shown in FIG. As shown in FIG. 2A, the waveform W100 is a waveform that changes gently with almost no drop in drive torque from immediately before to immediately after the upshift operation. The relationship between the acceleration of the vehicle 100 and the time at this time is a waveform W103 as shown in FIG. As shown in FIG. 2B, the waveform W103 is a waveform that changes gradually from immediately before to immediately after the shift-up operation with almost no drop in acceleration. Therefore, the shift shock that occurs with the shift-up operation hardly occurs, so that a sense of discomfort given to the driver can be eliminated.
[0088]
Next, the ECU 15 performs an upshift operation (step S15). At this time, in step S12, immediately before the shift-up operation, the lock-up clutch is duty-controlled to maintain the engine speed at a predetermined speed, and assist the electric motors 6a and 6b to replenish the insufficient torque. Therefore, the shift shock hardly occurs after the upshift operation. Therefore, the driver can drive comfortably with almost no shift shock.
[0089]
Next, the ECU 15 gradually increases the engine speed 20 and gradually decreases the assist torque by the electric motors 6a and 6b (step S16). Thus, after the upshift operation, the vehicle 100 is caused to run only by the driving torque from the engine 1.
[0090]
In the above embodiment, the shift operation is described as upshifting. However, the present invention is not limited to this, and the shift control of the present invention can be applied to downshifting.
[0091]
【The invention's effect】
As described above, according to the shift control device for a vehicle according to the present invention, the engine speed is reduced prior to shifting to reduce the torque step during shifting, and the motor lacks torque due to the reduced engine speed. To make up. Thus, the shift shock can be prevented, and the driver hardly feels a sense of discomfort caused by the shift shock.
[0092]
Further, prior to shifting, the motor is operated by the power generated by the generator while maintaining the engine speed at a predetermined speed and reducing the amount of use of the high-voltage battery. This replenishes the insufficient driving torque during the upshift operation. Therefore, it is possible to significantly reduce the capacity of the high-voltage battery while reducing the consumed fuel. Therefore, similarly to the above, it is possible to effectively reduce the shift shock generated at the time of the shift-up operation, and to remove the uncomfortable feeling given to the driver without limit.
[Brief description of the drawings]
FIG. 1 shows a system configuration of a vehicle that performs shift control according to the present invention.
FIG. 2 is a graph showing waveforms of respective characteristics in the shift control according to the present invention.
FIG. 3 shows a flowchart of shift control according to the first embodiment.
FIG. 4 is a graph showing a power generation characteristic of a generator, a fuel consumption characteristic, and an estimated value of a shift start time. 4 shows a relationship between an engine speed, a generator characteristic, and a fuel consumption characteristic.
FIG. 5 shows a flowchart of a shift control according to a second embodiment.
[Explanation of symbols]
1 engine
2 generator
3 belt
4 Inverter
5 High voltage battery
6 Front wheel drive
7 Automatic transmission
8 Hydraulic control device
9 Propeller shaft
10 Rear wheel drive
15 ECU
16 12V battery
17 DC / DC converter
100 vehicles

Claims (6)

Determining means for determining whether a predetermined shift condition has been satisfied;
When the shift condition is satisfied, while reducing the rotation speed of the internal combustion engine, a driving force adjusting unit that adjusts the driving force of the internal combustion engine by applying a driving force to an output shaft of the internal combustion engine,
A shift unit that executes a shift after adjusting the driving force. 2. The vehicle transmission according to claim 1, wherein the driving force adjusting unit increases the rotation speed of the internal combustion engine after the shift and decreases the driving force applied to an output shaft of the internal combustion engine. 3. Control device. 3. The vehicle according to claim 1, wherein the vehicle includes a generator, and the driving force adjusting unit controls the internal combustion engine to a predetermined rotation speed to generate power using the generator. 4. Control device. 4. The vehicle shift according to claim 3, wherein the driving force adjusting unit applies a driving force to an output shaft of the internal combustion engine by an electric motor and drives the electric motor by electric power obtained by the generator. 5. Control device. 5. The vehicle shift according to claim 3, wherein the predetermined rotation speed is a rotation speed at which the power generation efficiency of the generator becomes maximum and the fuel consumption rate of the internal combustion engine becomes minimum. 6. Control device. The shift control device for a vehicle according to any one of claims 1 to 5, wherein the shift means is started after a predetermined time estimated based on an accelerator pedal depression amount and a vehicle acceleration.

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