JP2004036710A - Driving system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the driveability by preventing a busy shift in a vehicle where rotational speed-torque characteristics of a vehicle drive source can be variably set. <P>SOLUTION: It is judged whether the torque characteristics of the vehicle drive source is in a first torque mode proper to an engine (S10). In the first torque mode, a gear ratio pattern A or a gear change step pattern A is selected (S12). When judged as not the first torque mode, a change gear ratio pattern B or a change gear step pattern B is selected (S14). When in not the first torque mode, the torque is enough even at a low rotational speed in comparison with the torque characteristics proper to the engine by the control of an electro-magnetically actuated valve and the torque assist of an electric motor. The change gear ratio B or the change gear step pattern B, which is greater in a change gear step in comparison with the change gear ratio pattern A or the change gear step pattern A, is selected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle drive system, and more particularly, to a vehicle drive system capable of changing a rotation speed-torque characteristic of a vehicle drive source.
[0002]
[Prior art]
In a vehicle, a transmission is provided between the engine and the driving wheels, and the speed ratio and the torque of the drive shaft are changed by selecting a gear ratio according to the traveling conditions of the vehicle, so that the engine performance is sufficiently exhibited. It is planned as follows. Examples of this transmission include a continuously variable transmission that can continuously change the gear ratio, and a stepped transmission that has a plurality of gears and selects a gear that matches the driving conditions of the vehicle from among them. Have been. As is well known, the change of the speed ratio in these transmissions is performed according to a so-called shift line (shift characteristic) set in accordance with the vehicle speed and the accelerator opening.
[0003]
[Problems to be solved by the invention]
In order to select a gear ratio according to the running conditions of the vehicle, the transmission is provided with a gear ratio pattern in which the gear ratio is changed stepwise from a gear with a large gear ratio to a gear with a small gear ratio. Then, even when the engine has a low low-speed torque, the starting is facilitated by using a gear having a large gear ratio.
[0004]
However, when a conventional gear ratio pattern is used for a vehicle drive source having a low-speed torque, a change in the gear ratio can be achieved even though there is not much need to use a gear having a sufficient torque and a large gear ratio. Is frequently performed step by step, resulting in a so-called busy shift, and the drivability is reduced.
[0005]
For example, in the case of a so-called hybrid vehicle in which an electric motor for torque assist is further provided in addition to the engine as a driving source of the vehicle, or in an engine including an electromagnetically driven valve that has recently been attracting attention, an engine in which the torque is relatively reduced. For example, when the electromagnetically driven valve is controlled so as to increase the torque even in the low-speed rotation region, a margin can be given to the low-speed torque.
[0006]
As described above, by controlling the electric motor, the electromagnetically driven valve, and the like, the torque characteristic of the entire drive source of the vehicle, that is, the rotation speed-torque characteristic can be variably set, and the torque can have a margin in a low speed rotation region. In this case, if a conventional speed ratio pattern is used, a so-called busy shift remains, and drivability may be reduced.
[0007]
An object of the present invention is to solve the problems of the prior art and to provide a vehicle drive system capable of preventing a busy shift and improving drivability in a vehicle in which a rotation speed-torque characteristic of a vehicle drive source can be variably set. is there.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a vehicle drive system according to the present invention includes: a torque characteristic setting unit configured to variably set a rotational speed-torque characteristic of a vehicle drive source; And a plurality of speed ratio patterns having different ratio steps, wherein the speed ratio pattern is selected according to a change in the torque characteristic by the torque characteristic setting means.
[0009]
With this configuration, it is possible to select a gear ratio pattern by changing gear ratio steps according to the degree of margin of torque due to a change in the rotation speed-torque characteristic of the vehicle drive source. Therefore, when there is enough torque, a busy shift can be prevented by using a gear ratio step different from the conventional one.
[0010]
In addition, in the selection of the gear ratio pattern, it is preferable to select a gear ratio pattern having a larger step ratio of the gear ratio as the torque characteristic is changed to a higher torque side. With this configuration, when high torque is output, the step of the gear ratio can be made larger, the frequency of gear ratio changes can be reduced, and a busy shift can be prevented.
[0011]
Further, the vehicle drive system according to the present invention includes a torque characteristic setting unit that variably sets a rotation speed-torque characteristic of a vehicle drive source, and a plurality of shift speed patterns having different numbers of shift speeds. The shift speed pattern is selected according to a change in the torque characteristic by a setting unit.
[0012]
Here, the number of gear stages refers to the number of gear stages that can be set from the maximum gear ratio to the minimum gear ratio. With this configuration, it is possible to select a shift speed pattern by changing the number of shift speeds in accordance with the degree of torque margin due to the change in the rotation speed-torque characteristic of the vehicle drive source. Therefore, when there is a margin for the torque, it is possible to prevent the busy shift by using a different number of gears than the conventional one.
[0013]
In addition, it is preferable that, in the selection of the shift speed pattern, a shift speed pattern having a smaller number of shift speeds is selected as the torque characteristic is changed to a higher torque side. With this configuration, when high torque is being output, the number of gear positions can be further reduced, and the frequency of changing gear positions can be reduced to prevent a busy shift.
[0014]
Preferably, the vehicle drive source includes a vehicle engine, and the torque characteristic setting means is an electric opening / closing intake valve or an electric opening / closing exhaust valve provided on the vehicle engine and capable of controlling opening and closing electrically. Preferably, the vehicle drive source includes a vehicle engine, and the torque characteristic setting means is an electric motor.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a vehicle drive system 10. The vehicle drive system 10 includes an engine 13 having an electromagnetic drive valve, an electric motor 14 for assisting torque of the engine 13, a torque converter 16 having a lock-up clutch 36, and a transmission 18 connected to an output shaft 20 on the drive wheel side. A power transmission device for supplying a driving force is provided. Further, the vehicle drive system 10 controls an electromagnetic valve control unit 22 that controls the torque characteristics of the engine 13, an electric motor control unit 24 that controls the torque characteristics of the electric motor 14, and controls the engagement operation of the lock-up clutch of the torque converter 16. A lock-up clutch control unit 26 and a shift control unit 28 that controls the transmission 18 are provided. Control of the entire vehicle drive system is performed by a vehicle electronic control unit (ECU) (not shown).
[0016]
Here, the engine 13 having the electromagnetically driven valve and the electric motor 14 correspond to the vehicle drive source 12, and the electromagnetic valve control unit 22 and the electric motor control unit 24 determine the rotation speed of the vehicle drive source − This corresponds to torque characteristic setting means 25 for variably setting the torque characteristic.
[0017]
The engine 13 is an internal combustion engine for running a vehicle. Each cylinder of the engine 13 is provided with an intake valve and an exhaust valve that are opened and closed by an electromagnetic actuator that is electrically controlled, that is, an electromagnetically driven valve.
[0018]
FIG. 2 shows the state of the electromagnetically driven valves 74 and 75 attached to the cylinder of the engine 13. The electromagnetically driven valves 74 and 75 correspond to electrically controlled intake and exhaust valves, respectively. As shown in FIG. 2, the engine 13 is provided with electromagnetic actuators 76 and 77 that open and close electromagnetically driven valves 74 and 75 of each cylinder, and the electromagnetic valve control unit 81 detects the rotation angle of the crankshaft 79. It has a function of controlling the operation timing of the electromagnetically driven valves 74 and 75 according to a signal from the crankshaft rotation angle sensor 80.
[0019]
The electromagnetic valve control unit 81 not only changes the operation timing to the optimal timing according to the engine load, but also provides a timing for operating the engine 13 for four cycles and a timing for operating the engine 13 in two cycles in accordance with the operation cycle switching command. Control. In addition, the engine speed can be controlled by the engine itself by changing the operation timing of the electromagnetically driven valves 74 and 75 or changing the number of working cylinders. For example, by opening and closing the exhaust valve according to normal control while closing the intake valve, the rotational energy can be consumed by the compression work of the piston, and the engine rotational speed can be forcibly reduced quickly. The degree of change in the engine speed can be adjusted by controlling the opening of the engine. Also, for example, even in the low-speed rotation region of the engine where the torque decreases, the electromagnetic drive valves 74 and 75 can be controlled to increase the torque.
[0020]
By controlling the electromagnetically driven valves 74 and 75 in this manner, the rotation speed-torque characteristics of the engine 13 can be variably set.
[0021]
FIG. 3 is a cross-sectional view of the electromagnetic actuators 76 and 77. The electromagnetic actuators 76 and 77 are connected to the electromagnetically driven valves 74 and 75 and are supported by the electromagnetically driven valves 74 and 75 so as to be movable in the axial direction thereof. A pair of electromagnets 84 and 85 are provided at positions sandwiching the electromagnet 82 in order to selectively attract the magnet 82, and a pair of springs 86 and 87 for urging the movable member 82 toward the neutral position. .
[0022]
The electric motor 14 is a motor that generates a vehicle driving force, and is connected to an output shaft of the engine 13. And it has a function of a torque assist that operates at a low rotational speed of the engine 13 to compensate for the insufficient torque, for example. When the output of the engine 13 is sufficient, the motor 14 can be used as a generator to provide a function of recovering excess energy. The sum of the torque of the engine 13 and the torque supplied by the electric motor 14 is transmitted to the torque converter 16 as the torque of the vehicle drive source. Control such as torque assist of the electric motor 14 is performed by the electric motor control unit 24 controlling an inverter control circuit (not shown).
[0023]
As described above, by controlling the torque characteristics of the electric motor 14, the rotation speed-torque characteristics of the entire vehicle drive source including the engine 13 and the electric motor 14 can be variably set.
[0024]
The torque converter 16 is a torque transmission unit that transmits the torque of the vehicle drive source side member to the transmission side member which is a driven side member by fluid. The torque converter 16 includes a pump wheel 32 connected to the output shaft 15 of the vehicle drive source, a turbine wheel 34 connected to the input shaft 17 to the transmission 18, and the pump wheel 32 and the turbine wheel 34. And a lock-up clutch 36 for directly connecting between the two. The lock-up clutch 36 performs torque amplification between the pump impeller 32 and the turbine impeller 34 via a fluid without engaging at the time when the torque of the vehicle drive source rises, and the torque of the vehicle drive source is sufficient. After standing up, it has a function of engaging and transmitting the torque of the vehicle drive source directly to the transmission. Further, in an intermediate state between the disengagement and the engagement, a slip control for transmitting a torque by sliding at a predetermined engagement pressure can be performed. The engagement of the lock-up clutch 36 is controlled by the lock-up clutch control unit 26 controlling an engagement hydraulic actuator (not shown).
[0025]
The transmission 18 is provided between the vehicle drive source and the drive wheels, and has a function of sufficiently exhibiting the performance of the vehicle drive source by selecting a gear ratio according to the traveling conditions of the vehicle. As is well known, the inside of the transmission 18 includes a plurality of planetary gears, and a plurality of brakes and the like for fixing movement of sun gears, ring gears and the like, which are components of the planetary gears. The gear ratio between the input shaft 17 of the transmission 18 and the output shaft 20 to the drive wheels is defined by a combination of the number of teeth of the sun gear and the ring gear of each planetary gear. The change of the gear ratio is performed according to a fixed gear ratio pattern. The transmission 18 has a plurality of speed ratio patterns, and the speed change control unit 28 controls the selection of the speed ratio patterns and the change of the speed ratio in the selected speed ratio patterns.
[0026]
FIG. 4 is a diagram showing an input / output relationship of an electronic control unit (ECU) 50 that controls the entire vehicle drive system. The electronic control unit 50 receives signals representing engine speed, vehicle speed, accelerator opening, and the like, determines running conditions of the vehicle, operating conditions of the engine, and the like, and sends an electromagnetic drive valve signal to the electromagnetic valve control unit 22. Output, and a motor controller signal is output to the motor control unit 24. Further, a reduction gear signal is output to the shift control unit 28, and an AT lock-up control solenoid signal is output to the lock-up clutch control unit 26.
[0027]
The operation of the vehicle drive system according to this embodiment will be described using the torque characteristics of the vehicle drive source shown in FIG. 5, that is, the rotation speed-torque characteristics. When neither the electromagnetically driven valve nor the electric motor operates, the torque characteristics of the vehicle drive source are torque characteristics specific to the engine. That is, as is generally known, the torque is low in a low rotation speed region, the torque increases as the rotation speed increases, and after reaching the maximum torque, the torque gradually increases as the rotation speed further increases. It becomes a torque characteristic curve that goes down. The torque characteristic curve peculiar to the engine, which becomes a mountain with respect to the change in the rotational speed, is referred to as a first torque mode 60.
[0028]
Next, the electromagnetic valve control unit 22 is controlled by the electromagnetic valve signal of the electronic control unit 50 to control the electromagnetic valve provided in the engine, so that the torque characteristics of the vehicle drive source can be set variably. For example, when it is detected from the engine speed signal that the engine speed has decreased, an electromagnetic valve signal for changing the opening / closing timing of the electromagnetic drive valve can be output to the electromagnetic valve control unit 22. Thus, for example, a torque characteristic curve can be obtained in which the torque does not decrease and is maintained as it is even when the rotational speed decreases from the rotational speed of the maximum torque. Now, a torque characteristic curve in which the electromagnetically driven valve is controlled and the torque is substantially constant at a low rotational speed will be referred to as a second torque mode 62.
[0029]
Further, by controlling the motor control unit 24 based on the motor controller signal of the electronic control device 50 to control the operation of the motor, the torque characteristics of the vehicle drive source can be variably set. For example, the output of the engine is estimated from the vehicle speed signal and the accelerator opening signal, and when it is detected that the estimated torque is low, a motor controller signal for instructing the motor control unit 24 to operate the motor can be output. Thus, for example, torque assist can be performed in a low rotational speed region to further increase the torque, thereby obtaining a torque characteristic curve that is larger than the engine-specific maximum torque. Now, the electric motor is controlled, and a torque characteristic curve falling rightward with respect to a change in the number of rotations is referred to as a third torque mode.
[0030]
As described above, when the torque characteristics of the vehicle drive source are changed by electrically controlling the electromagnetically driven valve or the electric motor, the electronic control unit 50 sends a signal to the transmission control unit 28 in accordance with the changed torque characteristics. A speed reducer signal is output. For example, different reduction gear signals are output depending on whether the torque mode is the first torque mode, the second torque mode, or the third torque mode, or among them, depending on the difference in torque characteristics. The speed reducer signal includes a control instruction relating to selection of a speed ratio pattern according to the changed torque characteristic and change of a speed ratio in the selected speed ratio pattern.
[0031]
FIGS. 6A and 6B show examples of the gear ratio pattern and the gear position pattern, respectively. The speed ratio pattern A and the speed step pattern A have a minimum speed (deceleration) ratio of 0.591, a maximum speed (deceleration) ratio of 3.721, eight speed stages, and a speed ratio between adjacent speed stages. The speed ratio step, which is the ratio, is 1.3, and the range of the speed ratio, which is the ratio between the maximum speed ratio and the minimum speed ratio, is 3.721 / 0.591.
[0032]
In the gear ratio pattern B and the gear ratio pattern B, the minimum gear ratio is the same as the gear ratio pattern A, the gear ratio step is set to 1.5 which is larger than the gear ratio pattern A, and the maximum gear ratio is the gear ratio pattern A 6 gears that can be brought closest to the maximum speed ratio of The range of the gear ratio at this time is 3.375 / 0.591, which is different from the gear ratio pattern A.
[0033]
The speed ratio pattern C and the speed ratio pattern C are the same as the speed ratio pattern A and the range of the speed ratio, and the speed ratio step is 1.3 * 1.3 = 1.69. That is, the gear ratio pattern C is obtained by increasing the gear ratio step by thinning out the gears of the gear ratio pattern A.
[0034]
FIG. 7 is a flowchart illustrating a procedure for selecting a gear ratio pattern or a gear step pattern according to the torque characteristics of the vehicle drive source. S10 is a torque mode determining step of determining whether the torque characteristic is in the first torque mode. The electronic control unit can determine the torque mode from the contents of the electromagnetic drive valve signal and the motor controller signal. For example, when the content of the electromagnetically driven valve signal is a normal valve opening / closing control instruction and the motor controller signal is a control instruction without torque assist, it can be determined that the first torque mode is set.
[0035]
S12 is a step of selecting the gear ratio pattern A or the gear position pattern A in the first torque mode. The electronic control unit selects a gear ratio pattern A or a gear step pattern A and outputs a speed reducer signal for performing a gear ratio change control in the selected gear ratio pattern. As described above, in the first torque mode specific to the engine, the shift is performed at a fine gear ratio.
[0036]
S14 is a step of proceeding when it is determined that the current mode is not the first torque mode, and is a step of selecting a gear ratio pattern B or a gear step pattern B. The electronic control unit outputs a reduction gear signal for selecting the gear ratio pattern B or the gear step pattern B to the shift control unit. When the mode is not the first torque mode, the mode is the second torque mode or the third torque mode, and the torque is sufficient even at a low rotational speed compared to the torque characteristics specific to the engine. Therefore, the vehicle can travel sufficiently at the current gear position, and there is little problem even if the gear ratio step is increased when gear shifting is required. Therefore, by selecting the gear ratio pattern B or the gear stage pattern B in which the gear ratio step is set larger than the gear ratio pattern A, the number of changes of the gear ratio can be reduced, and the busy shift can be prevented. Drivability can be improved.
[0037]
The electronic control unit can determine whether the mode is the second torque mode or the third torque mode based on the content of the motor controller signal. Therefore, when determining the third torque mode, the gear ratio pattern C or the gear position pattern C can be selected. Thereby, the change of the gear ratio can be further reduced as compared with the gear ratio pattern B and the like, and the drivability is further improved.
[0038]
Further, the magnitude of the torque characteristic can be determined in more detail from the contents of the electromagnetic drive valve signal and the contents of the electric motor controller signal, so that the gear ratio pattern A, the gear ratio pattern B, the gear ratio pattern C, etc. can be determined according to the magnitude of the torque characteristic. Selection criteria can be defined between.
[0039]
The change of the gear ratio in the selected gear ratio pattern can be performed so as to be compatible with the torque mode of the torque characteristic and the running conditions of the vehicle. That is, a suitable gear ratio is selected from a vehicle speed signal, an accelerator opening, an engine rotation speed signal, an electromagnetic drive valve signal, a motor controller signal, and the like.
[0040]
The change of the gear ratio can be performed by sequentially switching the gear position of the vehicle from the low gear position to the high gear position or from the high gear position to the low gear position at the shift position "D", that is, the forward change position by the automatic shift. Further, when a predetermined gear position is selected by + or-as in a so-called shift steermatic gear position hold type, a single + or-can be used to change to a different speed ratio.
[0041]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the vehicle drive system which concerns on this invention, in the vehicle which can set the rotation speed-torque characteristic of a vehicle drive source variably, a busy shift can be prevented and drivability can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a vehicle drive system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an electromagnetically driven valve provided in an engine.
FIG. 3 is a sectional view of an electromagnetic actuator.
FIG. 4 is a diagram showing an input / output relationship of the electronic control unit.
FIG. 5 is a diagram illustrating torque characteristics of a vehicle drive source.
FIG. 6 is a diagram showing an example of a gear ratio pattern and a gear position pattern in the embodiment according to the present invention.
FIG. 7 is a flowchart showing a procedure for selecting a gear ratio pattern or a gear step pattern in the embodiment according to the present invention.
[Explanation of symbols]
Reference Signs List 10 vehicle drive system, 12 vehicle drive source, 13 engine, 14 electric motor, 16 torque converter, 18 transmission, 22 solenoid valve control unit, 24 electric motor control unit, 28 shift control unit, 50 electronic control unit (ECU), 60 First torque mode, 62 Second torque mode, 64 Third torque mode, 74, 75 Electromagnetically driven valve, 76, 77 Electromagnetic actuator.

Claims (6)

Torque characteristic setting means for variably setting the rotational speed-torque characteristic of the vehicle drive source,
A plurality of speed ratio patterns having different speed ratio steps, which is a ratio between the speed ratio and the speed ratio,
And wherein the speed ratio pattern is selected in accordance with a change in the torque characteristic by the torque characteristic setting means. 2. The vehicle drive system according to claim 1, wherein the selection of the gear ratio pattern includes selecting a gear ratio pattern having a larger step ratio of the gear ratio as the torque characteristic is changed to a high torque side. 3. Characteristic vehicle drive system. Torque characteristic setting means for variably setting the rotational speed-torque characteristic of the vehicle drive source,
A plurality of shift speed patterns having different shift speeds;
A drive system for a vehicle, wherein the shift speed pattern is selected according to a change in the torque characteristic by the torque characteristic setting means. 4. The vehicle drive system according to claim 3, wherein the selection of the shift speed pattern includes selecting a shift speed pattern having a smaller number of shift speeds as the torque characteristic is changed to a high torque side. 5. Vehicle drive system. 5. The vehicle drive system according to claim 1, wherein the vehicle drive source includes a vehicle engine, and the torque characteristic setting unit is configured to electrically control opening and closing of the vehicle engine. 6. A drive system for a vehicle, wherein the drive system is a possible electric opening / closing intake valve or an electric opening / closing exhaust valve. The vehicle drive system according to any one of claims 1 to 4, wherein the vehicle drive source includes a vehicle engine, and the torque characteristic setting unit is an electric motor. .

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