JP2003247636A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve vehicle performance such as fuel consumption and starting acceleration by controlling a capacity coefficient of a fluid coupling in response to a change of engine torque characteristic. <P>SOLUTION: When high-load starting an engine having high-torque characteristic TE2 at low-rotation, a lock-up clutch provided in parallel with the fluid coupling is controlled for slip engagement to obtain a high transmission torque capacity characteristic TF2, a balance point when fully opening a throttle becomes a point b and the engine speed NE is lowered, and even if the engine speed NE does not sufficiently rise when starting, the predetermined torque is obtained to be advantageous in inertia, and starting acceleration performance is improved, and a power transmission loss of the fluid when starting is reduced to improve fuel consumption. When low-load starting or stopping, the lock-up clutch is released to obtain a low transmission torque capacity characteristic TF1, and engine speed NE when idling is lowered to improve fuel consumption. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device, and more particularly to control of a capacity coefficient of a hydraulic power transmission device.

[0002]

2. Description of the Related Art (a) An engine that generates power by burning fuel, and (b) a fluid power that is arranged between the engine and driving wheels to transmit power and control the capacity coefficient. A vehicle having a transmission device is known. The vehicle described in Japanese Patent Laid-Open No. 58-142065 is, for example, equipped with a torque converter as a fluid power transmission device, and the capacity of the torque converter is increased by increasing the amount of oil supplied to the torque converter when the vehicle is stopped. The coefficient is reduced to reduce the engine load when the vehicle is stopped and improve fuel efficiency.

[0003]

By the way, in recent years, for example, an electric opening / closing valve that can be electrically opened / closed as an intake valve or an exhaust valve of the engine has been proposed. In such an engine, opening / closing of the electric opening / closing valve is proposed. The torque characteristics can be controlled by changing the timing, lift amount, etc.
In the conventional capacity coefficient control of the fluid type power transmission device, no consideration is given to such control of the torque characteristic of the engine, and there are cases where sufficient performance is not always obtained.

The present invention has been made in view of the above circumstances. An object of the present invention is to control the capacity coefficient of a fluid type power transmission device in accordance with a change in the torque characteristic of an engine to improve fuel economy. And to improve vehicle performance such as start acceleration.

[0005]

In order to achieve such an object, the first invention is (a) an engine which generates power by combustion of fuel and whose torque characteristic changes, and (b)
A control device for a vehicle having a fluid type power transmission device capable of controlling a capacity coefficient while transmitting power while being arranged between the engine and driving wheels, and (c) torque characteristics of the engine. It has a capacity coefficient changing means for changing the capacity coefficient of the fluid type power transmission device according to the change of.

According to a second aspect of the invention, in the vehicle control device according to the first aspect of the invention, the capacity coefficient changing means is characterized in that the torque on the low rotation side of the engine is low and the torque on the low rotation side is high and the torque is low. When the rotational high torque characteristic is changed, the capacity coefficient of the fluid type power transmission device is increased.

According to a third aspect of the present invention, in the vehicle control device of the second aspect, the capacity coefficient changing means sets the capacity coefficient of the fluid type power transmission device when the engine has the low rotation and high torque characteristics and a high load starts. It is characterized by making it larger.

A fourth invention is the vehicle control device according to any one of the first invention to the third invention, wherein the capacity coefficient changing means comprises:
When the vehicle is stopped with the engine stopped, the capacity coefficient of the hydraulic power transmission device is increased regardless of the torque characteristic of the engine.

A fifth invention is the vehicle control device according to any one of the first invention to the fourth invention, wherein the capacity coefficient changing means comprises:
When the vehicle is stopped with the power transmission cut off by the neutral control, the capacity coefficient of the fluid type power transmission device is increased irrespective of the torque characteristic of the engine. The neutral control is a control that automatically cuts off power transmission by setting the transmission to neutral under certain conditions when the vehicle is stopped.

According to a sixth aspect of the present invention, in the vehicle control device according to any of the first to fifth aspects, the engine is an electrically operated on-off valve in which at least one of an intake valve and an exhaust valve can be electrically controlled to open and close, It is characterized in that the torque characteristic is controlled by the electrically operated on-off valve.

A seventh aspect of the present invention is the vehicle control apparatus according to any one of the first to sixth aspects, wherein the fluid power transmission device is a fluid coupling in which friction clutches are provided in parallel. The capacity coefficient is controlled by slip engagement control.

[0012]

In such a vehicle control device,
Since the capacity coefficient of the fluid type power transmission device is changed according to the change of the torque characteristic of the engine, the capacity coefficient of the fluid type power transmission device is increased when the low rotation and high torque characteristics are changed as in the second aspect of the invention. If so, high torque can be used before the engine speed increases, which is advantageous for the inertia, and the power transmission loss of the fluid during start running is reduced to improve fuel efficiency. By controlling the capacity coefficient in response to changes in the torque characteristics of the engine, it is possible to improve vehicle performance such as fuel consumption and start acceleration.

According to the third aspect of the invention, since the engine has low rotation and high torque characteristics and the capacity coefficient of the fluid type power transmission device is increased when starting a high load, excellent starting acceleration performance is obtained when starting a high load, while At the time, the capacity coefficient is small and the idle rotation speed is reduced, so the fuel efficiency is improved.

According to the fourth aspect of the invention, when the engine is stopped and the vehicle is stopped, the capacity coefficient of the hydraulic power transmission device is increased irrespective of the torque characteristic of the engine, but since the engine is stopped, it does not affect the fuel consumption.

In the fifth aspect of the invention, when the vehicle is stopped with the power transmission cut off by the neutral control, the capacity coefficient of the fluid type power transmission device is increased regardless of the torque characteristic of the engine, but the power transmission is cut off. It does not affect fuel economy.

A seventh aspect of the invention is a case where a fluid coupling which cannot obtain a torque amplifying action is used as a fluid type power transmission device. The slip engagement of a friction clutch provided in parallel with the fluid coupling is used. In control,
By increasing the entire capacity coefficient including the friction clutch, for example, in combination with the change to the low rotation and high torque characteristics of the engine as in the second aspect of the invention, the inertia amount of the engine at the time of starting is advantageously used to achieve an excellent start. Acceleration performance can be obtained.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is applied to a vehicle having at least an engine as a driving force source for traveling, and to a hybrid vehicle having an electric motor or a motor generator as a driving force source in addition to the engine. Can also be applied.

An engine having a controllable torque characteristic is preferably used, and for example, the low-rotation high-torque characteristic and the low-rotation low-torque characteristic are switched by the torque characteristic changing means. For example, it may change naturally for some reason. In that case, the torque characteristic may be detected and the capacity coefficient of the fluid type power transmission device may be increased or decreased according to the change in the torque characteristic.

An engine whose torque characteristics can be controlled is, for example, an electric opening / closing valve whose intake valve and exhaust valve are both electrically controlled to be opened / closed. However, only one of the intake valve and the exhaust valve is electrically opened / closed. The valve may be a valve, and the other may be opened and closed by a cam shaft that is rotationally driven in conjunction with the crankshaft.

The electrically operated on-off valve opens and closes by linearly reciprocating the valve body by an electromagnetic actuator provided for each on-off valve, or the cam shaft provided for each on-off valve is rotationally driven by an electric motor to open the valve. Although it is desirable to configure so that each on-off valve can be opened and closed independently, such as opening and closing, the cam shaft that is installed across the on-off valves of multiple cylinders is driven to rotate by an electric motor. Then, various modes can be adopted, such as opening and closing continuously at a predetermined timing.

The torque characteristics include, for example, intake / exhaust timing, lift amount (movement amount) of intake / exhaust valve, operating angle (opening / closing speed).
The torque characteristics can be changed by controlling, for example, and at least two types of torque characteristics can be switched, but it is also possible to be able to switch to three or more kinds of torque characteristics. Further, the switching of the torque characteristics may be arbitrarily switched by the driver's selection operation, but depending on the driving state such as the accelerator operation amount indicating the driver's output request amount and its changing speed. Various modes are possible, such as automatic switching.

The fluid type power transmission device capable of controlling the capacity coefficient is, for example, a fluid coupling or a torque converter in which friction clutches are provided in parallel, and the capacity coefficient can be changed by slip engagement control of the friction clutch. However, the capacity coefficient can be controlled by the pressure and flow rate of the fluid. In the case of the torque converter, the capacity coefficient can be changed by changing the angle of the stator.

The capacity coefficient can be changed in various modes such as switching in two stages or multiple stages or continuously in accordance with changes in torque characteristics. Further, the capacity coefficient may be changed as long as it can substantially change the characteristic of the transmission torque with respect to the input / output rotational speed difference.

The high load starting of the third aspect of the invention is, for example, a case where the accelerator operation amount indicating the output demand of the driver is equal to or greater than a predetermined value, or the rate of change of the accelerator operation amount is equal to or greater than a predetermined value. In the third aspect of the invention, the capacity coefficient of the fluid type power transmission device is reduced during normal times such as low load starting other than high load starting or when the vehicle is stopped. In the case of characteristics, it is possible to increase the capacity coefficient even when the vehicle is starting at a high load such as when the vehicle is stopped.

When the engine of the fourth invention is stopped and the vehicle is stopped,
For example, when the eco-run control is performed in which the engine is automatically stopped under a certain condition (the engine temperature is equal to or higher than a predetermined temperature) when the vehicle is stopped.

[0026]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a skeleton diagram illustrating the configuration of a power transmission device 8 of a hybrid vehicle to which the present invention is applied. In FIG. 1, an output of an engine 10 as a driving force source for traveling configured by an internal combustion engine is input to an automatic transmission 16 via an input clutch 12 and a fluid coupling 14 as a fluid power transmission device. It is adapted to be transmitted to the drive wheels via a differential gear unit and an axle not shown. A first motor generator MG1 that functions as an electric motor and a generator is arranged between the input clutch 12 and the fluid coupling 14. The fluid coupling 14 is the input clutch 1
2 is connected to the pump impeller 20, a turbine impeller 24 is connected to the input shaft 22 of the automatic transmission 16, and a lockup clutch 26 for directly connecting the pump impeller 20 and the turbine impeller 24. And are equipped with. The lockup clutch 26 is a hydraulic friction clutch that is frictionally engaged by hydraulic pressure.

The automatic transmission 16 is provided with a first transmission section 32 for switching between high and low gears, and a second transmission section 34 for switching between reverse gear and four forward gears. The first transmission unit 32 includes an HL planetary gear device 36 including a sun gear S0, a ring gear R0, and a planet gear P0 rotatably supported by the carrier K0 and meshed with the sun gear S0 and the ring gear R0.
A clutch C0 and a one-way clutch F0 provided between the sun gear S0 and the carrier K0, and a brake B0 provided between the sun gear S0 and the housing 38 are provided.

The second speed change portion 34 comprises a sun gear S1, a ring gear R1, and a planet gear P1 rotatably supported by the carrier K1 and meshed with the sun gear S1 and the ring gear R1.
, Sun gear S2, ring gear R2, and carrier K
2 and a second planetary gear device 42 that is rotatably supported by the sun gear S2 and a ring gear R2 and is meshed with the sun gear S2 and the ring gear R2; S3 and a third planetary gear set 44 including a planetary gear P3 meshed with the ring gear R3.

The sun gear S1 and the sun gear S2 are integrally connected to each other, the ring gear R1, the carrier K2 and the carrier K3 are integrally connected, and the carrier K3 is connected to the output shaft 46. The ring gear R2 is integrally connected to the sun gear S3 and the intermediate shaft 48. A clutch C1 is provided between the ring gear R0 and the intermediate shaft 48, and the sun gear S1 and the sun gear S2 are provided.
And a ring gear R0, a clutch C2 is provided. Further, a band-type brake B1 for stopping the rotation of the sun gear S1 and the sun gear S2 is provided in the housing 38.
It is provided in. A one-way clutch F1 is provided between the sun gear S1 and the sun gear S2 and the housing 38.
And the brake B2 are provided in series. The one-way clutch F1 is configured to be engaged when the sun gear S1 and the sun gear S2 try to rotate in the opposite direction to the input shaft 22.

A brake B3 is provided between the carrier K1 and the housing 38, and a brake B4 and a one-way clutch F2 are provided in parallel between the ring gear R3 and the housing 38. This one-way clutch F
2 is configured to be engaged when the ring gear R3 tries to rotate in the reverse direction.

In the automatic transmission 16 configured as described above, for example, one reverse speed and a gear ratio (rotational speed Nin of the input shaft 22 / rotational speed Nout of the output shaft 46) sequentially differ according to the operation table shown in FIG. It is switched to any of the five forward speeds (1st to 5th). In Figure 2, "○"
Indicates engagement, blank indicates release, “⊚” indicates engagement at the time of driving force source braking by engine braking or regenerative braking of the first motor generator MG1, and “Δ” indicates engagement not involved in power transmission. It represents. The fourth gear "4t
In "h" and the fifth speed "5th", the engine brake is always applied. The clutches C0 to C2 and the brakes B0 to B4 are all hydraulic friction engagement devices that are engaged by hydraulic actuators.

As shown in FIG. 3, an exhaust turbine supercharger 54 is provided in the intake pipe 50 and the exhaust pipe 52 of the engine 10, and the exhaust pipe 52 has a bypass having a waste gate valve 56. The passages 58 are provided in parallel, and by controlling the flow rate of the exhaust gas flowing through the bypass passages 58, it is possible to change the turbine rotation and adjust the supercharging pressure in the intake pipe 50. The intake pipe 50 is provided with an electronic throttle valve 62 whose opening and closing is controlled by a throttle actuator 60. The electronic throttle valve 62 is basically controlled so as to have an opening degree θ _TH corresponding to the accelerator operation amount A _CC that represents the driver's output request amount, but the output of the engine 10 is appropriately adjusted according to the driving state. Therefore, the opening / closing control is performed independently of the accelerator operation amount A _CC at the time of transition of gear shift.

As shown in FIG. 4, the engine 10 includes a variable valve mechanism 78 including electromagnetic actuators 76 and 77 for opening and closing the intake valve 74 and the exhaust valve 75 of each cylinder, and a rotation angle of a crankshaft 79. The intake valve 74 according to a signal from the crankshaft rotation angle sensor 80 for detecting
And a valve drive control device 81 for controlling the operation timing (timing) of the exhaust valve 75. The valve drive control device 81 not only changes the operation timing to the optimum timing according to the engine load, but also becomes the timing for operating the engine 10 for 4 cycles and the timing for operating the engine 10 in accordance with the operation cycle switching command. To control. The electromagnetic actuators 76 and 77 have an intake valve 74 or an exhaust valve 75, for example, as shown in FIG.
And a disk-shaped movable member 82 made of a magnetic material, which is movably supported in the axial direction of the intake valve 74 or the exhaust valve 75 and is selectively attracted to the movable member 82. A pair of electromagnets 84, 85 provided at the sandwiching position,
A pair of springs 86, 87 for urging the movable member 82 toward its neutral position are provided. The intake valve 74 and the exhaust valve 75 correspond to electrically-operated opening / closing valves whose opening / closing can be electrically controlled.

The first motor generator MG1 is arranged between the engine 10 and the automatic transmission 16, and the input clutch 12 is the engine 10 and the first motor generator MG.
It is arranged between 1 and 1. Each hydraulic friction engagement device and lock-up clutch 26 of the automatic transmission 16 are
The hydraulic pressure control circuit 66 controls the hydraulic pressure generated from the electric hydraulic pump 64 as the original pressure. A second motor generator MG2 is operatively connected to the engine 10. Then, the fuel cell 70 and the secondary battery 71 functioning as the power source of the first motor generator MG1 and the second motor generator MG2, and the currents supplied from them to the first motor generator MG1 and the second motor generator MG2 are controlled. Alternatively, power supply changeover switches 72 and 73 for controlling the current supplied to the secondary battery 71 for charging are provided. The power source changeover switches 72 and 73 indicate devices having a switch function, and may be constituted by, for example, a semiconductor switching element having an inverter function or the like.

FIG. 6 is a block diagram for explaining a control system provided in the power transmission device 8 of this embodiment, and shows a signal input to the electronic control device 90 and a signal output from the electronic control device 90. The engine speed (NE) sensor 92, turbine speed (NT) sensor 94, vehicle speed (V) sensor 96, throttle valve opening (θ _TH ) sensor 97, accelerator operation amount (A _CC ) sensor are shown as examples. 9
8, the foot brake switch 100, the shift position sensor 102, the secondary battery fuel gauge 108, etc., the engine rotation speed NE, the turbine rotation speed NT (the same as the rotation speed Nin of the input shaft 22), the vehicle speed V (of the output shaft 46 (Corresponding to the rotation speed Nout), the throttle valve opening θ _TH of the electronic throttle valve 62, the accelerator pedal operation amount A _CC , the foot brake ON / OFF, the shift position P _SH which is the operation position of the shift lever (not shown), the secondary Remaining capacity S of battery 71
A signal representing OC, etc. is supplied.

The electronic control unit 90 includes a CPU, RO
It is configured to include a so-called microcomputer including M, RAM, an input / output interface, etc.
By performing signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the engine 1, the engine 1 is operated by the throttle actuator 60, the valve drive control device 81, the ignition device 112, the fuel injection device 114, and the like.
0 output control, MG1 controller 116,
Motor generator M by MG2 controller 118
The automatic transmission 16 is performed by performing power running control and regenerative control of G1 and MG2, and switching the hydraulic circuit by exciting or non-exciting the AT shift solenoid 120 of the hydraulic control circuit 66.
Of the lock-up control solenoid 122, the lock-up control solenoid 122 switches engagement (including slip engagement) and disengagement of the lock-up clutch 26, and various other controls are executed. AT shift solenoid 1
Reference numeral 20 changes the operating state of a switching valve or the like to switch the hydraulic circuit, thereby switching the engagement and release states of the clutches C0 to C2 and the brakes B0 to B4, and the plurality of shift speeds and the neutral "N". It is for the purpose of establishing the above, and a plurality is provided.

As shown in FIG. 7, the electronic control unit 90 also executes each function of the engine torque characteristic changing means 130, the eco-run control means 132, the neutral control means 134, and the capacity coefficient changing means 136 by signal processing. It has become. Engine torque characteristic changing means 1
Reference numeral 30 is for changing the torque characteristic of the engine 10 by controlling the opening / closing timing, the lift amount, and the operating angle (opening / closing speed) of the intake valve 74 and the exhaust valve 75 via the valve drive control device 81. 9 includes two types, a low rotation low torque characteristic TE1 where the torque on the low rotation side of the engine 10 is low as shown by the solid line in FIG. 9 and a low rotation high torque characteristic TE2 where the torque on the low rotation side is high as shown by the dotted line. Torque characteristics are predetermined and are switched according to a driving mode such as a sports driving mode arbitrarily selected by the driver, or automatically switched according to driving conditions such as the accelerator operation amount A _CC and its change speed. It is supposed to be. The low-rotation low-torque characteristic TE1 and the low-rotation high-torque characteristic TE2 are torque change characteristics with respect to the engine rotation speed NE, and the electronic throttle valve 62 is in the fully open state (θ _TH = 100%).

The eco-run control means 132 executes eco-run control for automatically stopping the engine 10 by stopping fuel injection control, ignition control, etc. under a certain condition when the vehicle speed is V = 0. . Further, the neutral control means 134 releases the clutch C1 under a certain condition to set the automatic transmission 16 to the neutral "N" when the vehicle speed V = 0 is stopped (see FIG. 2), whereby the engine 10 is operated.
Also, the neutral control is executed to automatically cut off the power transmission between the driving force source including the first motor generator MG1 and the driving wheels.

The capacity coefficient changing means 136 is used for the engine 10
The overall capacity coefficient of the fluid coupling 14 including the lock-up clutch 26 is controlled according to the torque characteristics of the engine, the presence or absence of eco-run control, the presence or absence of neutral control, and the like. The total torque is controlled, and signal processing is performed according to the flowchart of FIG. In step S1 of FIG. 8, whether or not the vehicle is substantially stopped, specifically, the vehicle speed V is 5 to 10 km /
It is determined whether or not the vehicle is starting at a speed equal to or less than a predetermined vehicle speed or completely stopped. If the vehicle is substantially stopped, steps S2 and thereafter are executed. The present control relates to control when the vehicle is stopped or started, and engagement and disengagement control of the lockup clutch 26 during traveling is appropriately determined separately.

In step S2, it is determined whether or not the neutral control means 134 is performing the neutral control. If the neutral control is being performed, step S6 is immediately executed to lock the lock-up clutch 26 with a predetermined engagement torque. The capacitance coefficient of the fluid coupling 14 is increased by controlling the engagement. During the neutral control, the fluid coupling 14 rotates integrally with the engine 10 and almost no load is applied to the engine 10.
Even if the lockup clutch 26 is controlled to be engaged, there is no fear that fuel efficiency will deteriorate.

When the neutral control is not being executed,
In step S3, it is determined whether or not the eco-run control means 132 is performing the eco-run control. If the eco-run control is being executed, step S6 is immediately executed to control the lock-up clutch 26 with a predetermined engagement torque. By doing so, the capacitance coefficient of the fluid coupling 14 is increased. Since the engine 10 is stopped during the eco-run control, the rotation of the fluid coupling 14 is also stopped, and even if the lockup clutch 26 is engagement-controlled, there is no fear that fuel consumption will deteriorate.

If neither the neutral control nor the eco-run control is being performed, in step S4, it is determined whether or not the accelerator operation amount A _CC is a high load starting above a predetermined value, and if it is a high load starting, step S5 is executed. When the vehicle is not in the high load starting state, that is, when the accelerator operation amount A _CC is a predetermined value or less and the low load starting or the vehicle is stopped, step S7 is executed. In step S7, the lock-up clutch 26 is released to reduce the capacity coefficient of the entire fluid coupling 14 including the lock-up clutch 26 to obtain the low transfer torque capacity characteristic TF1. An alternate long and short dash line in FIG. 9 is an example of the low transmission torque capacity characteristic TF1 at this time. The output side, that is, the rotational speed of the turbine impeller 24 is 0 and the engine rotational speed NE is the same as the input / output rotational speed difference of the fluid coupling 14. When the throttle is fully opened, the torque characteristic of the engine 10 is low rotation low torque characteristic TE1,
In any case of the low rotation and high torque characteristics TE2, the points a are balanced.

Step S5 executed in the case of starting a high load
Then, whether or not the low rotation torque up control is being performed, that is, the engine torque characteristic changing means 130 causes the engine 1
It is determined whether or not 0 is the low rotation / high torque characteristic TE2. If it is not the low rotation / high torque characteristic TE2, that is, if it is the low rotation / low torque characteristic TE1, the step S7 is executed, but the low rotation / high torque characteristic TE2 is executed. If so, step S6 is executed and the lockup clutch 26 is engagement-controlled with a predetermined engagement torque to increase the overall capacity coefficient of the fluid coupling 14 to obtain the high transmission torque capacity characteristic TF2. At the time of executing step S6 at this time,
While the engine 10 is operated in the predetermined throttle state of the low rotation / high torque characteristic TE2, the input shaft 22 or the turbine impeller 24 stops rotating when stopped and is in the low rotation state when starting. The lockup clutch 26 is in a predetermined slip state. The chain double-dashed line in FIG. 9 is an example of the above-mentioned high transmission torque capacity characteristic TF2, and is a case where the rotational speed of the turbine impeller 24 is 0 and the engine rotational speed NE is the input / output rotational speed difference of the fluid coupling 14 as it is. When the vehicle is stopped immediately after depressing the accelerator pedal, the engine speed N is balanced at a point b which is an intersection with the low rotation / high torque characteristic TE2, and compared with the point a.
E decreases. Low rotation and high torque characteristics TE2 of this embodiment
Is set so that the torque on the lower rotation side than the point a becomes substantially the same torque as the point a, but it can be changed as appropriate.

In the power transmission device 8 of the present embodiment as described above, step S6 is executed and the lockup clutch 26 is set to a predetermined value when the engine 10 has the low rotation and high torque characteristics TE2 at the time of starting the high load. By performing slip engagement control with the engagement torque of, the capacity coefficient of the fluid coupling 14 is increased to increase the high transmission torque capacity characteristic TF.
Therefore, the balance point when the throttle is fully opened becomes point b, the engine speed NE becomes low, and a predetermined torque can be extracted even when the engine speed NE does not increase at the time of starting. The performance is improved, and the power transmission loss of the fluid at the time of starting traveling is reduced to improve the fuel efficiency.

On the other hand, in the present embodiment, step S7 is executed when the vehicle starts at a low load or when the vehicle is stopped, and the lockup clutch 26
Is released to reduce the capacity coefficient of the fluid coupling 14 to achieve the low transmission torque capacity characteristic TF1, so that the engine speed NE is reduced to improve fuel efficiency, and the fluid coupling 14 enables smooth starting performance. can get.

Further, in this embodiment, the fluid coupling 14 is used as the fluid type power transmission device in which the torque amplifying action is not obtained. However, the slip engagement control of the lockup clutch 26 causes a high transmission torque having a large capacity coefficient. Capacity characteristic TF2 and engine torque characteristic changing means 1
By setting the low rotation / high torque characteristic TE2 by 30, the engine rotation speed NE at the time of starting is reduced to the state of the approximate point b. Therefore, even if the engine rotation speed NE at the time of starting does not increase, a predetermined torque is obtained. Since it can be pulled out, it is advantageous in terms of inertia and excellent starting acceleration performance can be obtained.

In the above example, when the torque characteristic of the engine 10 is changed by the engine torque characteristic changing means 130 and the low rotation / high torque characteristic TE2 is selected, the fluid coupling 14 has the high transmission torque capacity characteristic T.
F2 is set, but when the torque characteristic of the engine 10 is monitored and the torque characteristic of the engine 10 changes due to some reason such as a change over time, the capacity coefficient (transmission) of the fluid coupling 14 is changed according to the change mode. The torque capacity characteristic) may be changed continuously or stepwise.

The embodiments of the present invention have been described in detail above with reference to the drawings. However, these are merely embodiments, and the present invention includes various modifications and improvements based on the knowledge of those skilled in the art. Can be implemented in.

[Brief description of drawings]

FIG. 1 is a skeleton diagram illustrating a vehicle power transmission device to which the present invention is applied.

2 is a diagram showing a relationship between a combination of operations of a plurality of hydraulic friction engagement devices in the automatic transmission of FIG. 1 and a shift speed established thereby.

FIG. 3 is a schematic configuration diagram of the vehicle power transmission device of FIG. 1.

FIG. 4 is a diagram illustrating a variable valve mechanism provided in each cylinder of the engine of FIG.

5 is a diagram illustrating a configuration of an electromagnetic actuator that is provided in the variable valve mechanism of FIG. 4 and that opens and closes an intake valve or an exhaust valve.

FIG. 6 is a block diagram illustrating a main part of a control system included in the vehicle power transmission device of FIG. 1.

7 is a block diagram illustrating a part of the functions executed by the electronic control unit (ECU) of FIG.

8 is a flowchart illustrating specific processing contents of a capacity coefficient changing unit in FIG. 7. FIG.

9 is a diagram illustrating an example of an engine torque characteristic switched by the engine torque characteristic changing means of FIG. 7 and an example of a transmission torque capacity characteristic of a fluid coupling changed by a capacity coefficient changing means.

[Explanation of symbols]

10: Engine 14: Fluid Coupling (Fluid Power Transmission Device) 26: Lockup Clutch (Friction Clutch) 7
4: Intake valve (electric on-off valve) 75: Exhaust valve (electric on-off valve) 90: Electronic control unit
136: Capacity coefficient changing means TE1: Low rotation and low torque characteristics TE2: Low rotation and high torque characteristics

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 13/02 F02D 13/02 HF term (reference) 3D041 AA21 AA30 AA32 AB01 AC01 AC08 AD02 AD04 AD10 AD14 AD22 AD31 AD41 AD51 AE23 AF01 3G018 AB09 BA38 CA12 EA26 GA06 GA07 3G092 AA01 AA11 AA14 AC03 BA02 DA07 DA11 DG09 EA01 EA02 EA03 EA04 EA11 FA02 GA05 GA10 GA17 HA06Z HE01Z HE01Z HE08Z HF12Z HF15Z DH21Z05 CA14Z3

Claims (7)

[Claims] 1. A fluid type engine, which generates power by combustion of fuel and has torque characteristics that change, and which is arranged between the engine and driving wheels to transmit power and whose capacity coefficient can be controlled. A vehicle control device including a power transmission device, comprising: a capacity coefficient changing unit that changes a capacity coefficient of the fluid type power transmission device according to a change in torque characteristics of the engine. Control device. 2. The capacity coefficient changing means, when the low rotation low torque characteristic of the low rotation side of the engine is changed from the low rotation low torque characteristic to the low rotation high torque characteristic of which the low rotation side torque is high, the fluid type The vehicle control device according to claim 1, wherein a capacity coefficient of the power transmission device is increased. 3. The capacity coefficient changing means increases the capacity coefficient of the fluid type power transmission device when the engine has the low rotation and high torque characteristics and a high load is started. Vehicle control device. 4. The capacity coefficient changing means increases the capacity coefficient of the fluid type power transmission device irrespective of the torque characteristic of the engine when the vehicle is stopped with the engine stopped. The vehicle control device according to any one of 3 above. 5. The capacity coefficient changing means increases the capacity coefficient of the fluid type power transmission device irrespective of the torque characteristic of the engine when the vehicle is stopped with power transmission cut off by neutral control. Claim 1
The vehicle control device according to any one of 4 above. 6. The engine according to claim 1, wherein at least one of an intake valve and an exhaust valve is an electrically-operated opening / closing valve whose opening / closing can be electrically controlled, and a torque characteristic is controlled by the electrically-operating opening / closing valve. The vehicle control device according to any one of 5 above. 7. The fluid power transmission device is a fluid coupling in which friction clutches are provided in parallel, and the capacity coefficient is controlled by slip engagement control of the friction clutches. The vehicle control device according to any one of 1 to 6.