JP2003129875A - Control system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve compatibility between the responsivity to acceleration and fuel consumption by controlling valve timing and the change gear ratio of a continuously variable transmission in cooperation with each other. SOLUTION: The system includes: output increasing means (steps S3, S4) which controls the operation state of an intake valve toward high output torque side, if it is determined by output requirement determining means (steps S1, S2) that the output requirement is not less than the predetermined value, and changes the change gear ratio of the continuously variable transmission to an increasing number of revolutions of an internal combustion engine as well; and resetting means (step S6) which controls the operating state of the intake valve to the predetermined operating state based on fuel-efficiency, after the operating state of the intake valve and the change gear ratio of the continuously variable transmission have been controlled by the output increasing step and the travelling state of the vehicle has come to a specified state, and controls the change gear ratio of the continuously variable transmission so that it becomes the change gear ratio at which the number of revolutions of the internal combustion engine comes to the predetermined number of revolutions taking fuel consumption into account.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle in which an internal combustion engine capable of changing at least an operation state such as an operation timing of an intake valve is connected to a continuously variable transmission capable of continuously changing a gear ratio. It is about.

[0002]

2. Description of the Related Art Conventionally, a hybrid vehicle has been known as a technique for improving the fuel efficiency of a vehicle. An example thereof is described in Japanese Patent Laid-Open No. 2000-170569. The device described in this publication is a control device for a hybrid vehicle having an internal combustion engine and a motor as power sources,
When traveling from the partial load range to the full load range of the engine, the assist amount by the motor is gradually increased.

Therefore, according to this type of device, the internal combustion engine can be operated in a state where the fuel consumption is optimized, and the energy can be regenerated at the time of deceleration to be used as the energy for driving the motor, so that the fuel consumption can be improved. Further, the torque can be supplemented by the motor at the time of acceleration, so that the acceleration performance can be maintained.

[0004]

However, the device described in the above publication is intended for a hybrid vehicle having a plurality of power sources, and is a general vehicle using only an internal combustion engine as a power source. Cannot be applied to. That is, since a hybrid vehicle is equipped with a plurality of power sources, not only the number of power sources increases, but also a mechanism for connecting those power sources to a drive mechanism such as a transmission and those power sources. A mechanism for selectively using, and a device for controlling each are required. As a result, the size of the entire apparatus becomes large and the in-vehicle performance deteriorates, and the number of constituent members increases and becomes complicated, resulting in higher manufacturing costs. Further, the weight increase may impair the effect of reducing fuel consumption.

The present invention has been made by paying attention to the above technical problems, and it is possible to reduce fuel consumption by cooperatively controlling at least an internal combustion engine in which the operating state of an intake valve is variable and a continuously variable transmission. An object of the present invention is to provide a control device that can achieve both acceleration and acceleration.

[0006]

In order to achieve the above-mentioned object, the invention according to claim 1 is such that when the operating state of the intake valve can be changed and the required output amount is relatively small, the fuel consumption is reduced. For an internal combustion engine whose intake valve is controlled to a predetermined operating state based on efficiency, a continuously variable transmission ratio is controlled so that the rotational speed of the internal combustion engine becomes a preset rotational speed in consideration of fuel consumption. In a control device for a vehicle to which a transmission is connected, an output request determination unit that determines whether an output request amount is a predetermined value or more, and the output request determination unit determines that the output request amount is a predetermined value or more Output control means for controlling the operating state of the intake valve to the high output torque side and changing the gear ratio of the continuously variable transmission in the direction in which the rotational speed of the internal combustion engine increases, Valve operation State and the gear ratio of the continuously variable transmission are controlled by the output increasing means so that the running state of the vehicle becomes a predetermined state, and then the operating state of the intake valve is predetermined based on the fuel efficiency. A reset means for controlling the operating state and controlling the speed ratio of the continuously variable transmission to a speed ratio at which the rotation speed of the internal combustion engine becomes a predetermined rotation speed in consideration of fuel consumption. It is a characteristic control device.

Therefore, according to the first aspect of the invention, when the required output amount exceeds a predetermined value, the operating state of the intake valve is changed so that the output torque of the internal combustion engine increases, and the rotational speed of the internal combustion engine changes. The gear ratio of the continuously variable transmission is changed so as to increase. As a result, the drive torque rapidly increases as the output torque of the internal combustion engine increases, and its output increases as the rotational speed of the internal combustion engine increases.
It is possible to obtain the acceleration performance according to the output demand. After the running state of the vehicle reaches a predetermined state by increasing the output of the internal combustion engine in this way, the operating state of the intake valve and the gear ratio of the continuously variable transmission are set in consideration of fuel consumption. Controlled by. Therefore, fuel efficiency is improved without impairing acceleration response.

According to the second aspect of the present invention, the output increasing means includes the intake valve when the output request determining means determines that the output request amount is equal to or more than a predetermined value. It may be a means for controlling the opening / closing timing of the advance angle.

Therefore, in the second aspect of the invention, the internal combustion engine is normally operated at a relatively high expansion ratio to improve fuel efficiency, and when the output demand is large, the expansion ratio is relatively lowered. As a result, the output torque is increased and the acceleration response of the vehicle is improved.

Further, the output increasing means in the present invention is, as described in claim 3, an operating state in which the operating state of the intake valve is increased to a state where the torque of the internal combustion engine becomes a full load torque generating state. It may be a means for controlling.

Therefore, in the third aspect of the present invention, when the output demand increases, the output torque of the internal combustion engine is increased to the limit, and as a result, the acceleration response is improved.

Further, according to the fourth aspect of the present invention, the return means is configured to output the required output amount after the output of the internal combustion engine reaches a predetermined output based on the required output amount. It may be a means for controlling the operating state of the intake valve and the gear ratio of the continuously variable transmission so as to satisfy the above condition.

Therefore, according to the fourth aspect of the present invention, the output torque of the internal combustion engine is increased by changing the operating state of the intake valve, and thereafter the operating state is made to satisfy the output demand with the optimum fuel consumption. Both fuel efficiency is improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described based on a specific example shown in the drawings. First, a vehicle to which the present invention is applied will be described. In FIG. 3, a continuously variable transmission (CVT) 2 is connected to an output side of an engine 1, and a differential is connected to an output side of the continuously variable transmission 2. The left and right drive wheels 4 are connected via 3.

The engine 1 is a reciprocating engine having an intake valve 6 and an exhaust valve 7 which are opened and closed in accordance with the reciprocating movement of a piston 5, and more specifically, a gasoline engine. The engine 1 is a high expansion ratio engine having an expansion ratio larger than the compression ratio, and the high expansion ratio cycle is achieved by delaying the closing timing of the intake valve 6.

An example thereof is also shown in FIG. 3, and the reference symbol A indicates the period during which the intake valve 6 is open, and the reference symbol B indicates the period during which the exhaust valve 7 is open. The timing at which the intake valve 6 closes is a point that exceeds the bottom dead center BDC of the piston 5 by a predetermined angle θa, whereas the timing at which the exhaust valve 7 opens is a predetermined angle θb from the bottom dead center BDC of the piston 5. (<Θa) This is the previous point.
Here, the closing timing θa of the intake valve 6 is 60
The angle is set to at least 65 degrees, and preferably at 65 degrees or more. By setting such an angle, the rate of increase of the expansion ratio with respect to the compression ratio becomes large, so that the effect of improving fuel efficiency is improved. The compression ratio is set to "11.5" or more, preferably "12" or more. By doing so, fuel efficiency is improved.

Further, the engine 1 is provided with a variable valve timing mechanism (VVT) 8 for changing the opening / closing timing of the intake valve 6 and the exhaust valve 7. Therefore, by changing the closing timing of the intake valve 6 by the variable valve timing mechanism 8, the expansion ratio changes.

In the engine 1 shown in FIG. 3, the closing timing of the intake valve 6 is controlled on the basis of the engine load (throttle opening degree). For example, as shown in FIG. Compared to this, the closing time is accelerated. That is, the opening / closing timing of the intake valve 6 is advanced. The degree of advancement is increased according to the engine load, and the higher the engine load, the earlier the closing timing. Or if the engine load exceeds a specified value,
Alternatively, in addition to this, when the rate of change is large, the valve timing is changed so that the full load torque is generated.

In short, the continuously variable transmission 2 is a transmission in which the input rotation speed (engine rotation speed) can be appropriately set by changing the gear ratio steplessly (continuously). Therefore, a belt type continuously variable transmission, a traction type (toroidal type) continuously variable transmission, or the like can be adopted.

The gear ratio of the continuously variable transmission 2 is the same as that of a vehicle equipped with an ordinary continuously variable transmission in the steady running state.
The engine speed is controlled so that the fuel economy is the best. For example, the target driving force is obtained based on the required output amount represented by the accelerator pedal depression amount (accelerator opening) and the vehicle speed, and the target output for outputting the target driving force is the target driving force and the vehicle speed. Is calculated based on and. The target input speed (target engine speed) is obtained based on the map so as to obtain the target output in the most fuel-efficient state, and the gear ratio of the continuously variable transmission 2 is adjusted so as to achieve the target input speed. Is controlled. On the other hand, the target torque is calculated based on the target output and the engine speed, and the load of the engine 1 is controlled so as to achieve the obtained target torque.

An electronic control unit (E-ECU) 9 for controlling the throttle opening (load) and valve timing of the engine 1 described above is provided. Further, an electronic control unit (T-ECU) 10 for controlling the gear ratio and torque capacity (for example, belt clamping pressure) of the continuously variable transmission 2 is provided. The electronic control units 9 and 10 are mainly composed of a microcomputer as an example,
In addition, they are connected to each other so that data communication is possible.

Further, data such as vehicle speed, accelerator opening, engine speed, engine water temperature and the like are input to these electronic control units 9 and 10. Then, the electronic control units 9 and 10 perform calculations on the basis of the input data and the data such as the map stored in advance and the program stored in advance to determine the engine 1 and the continuously variable transmission 2. It is designed to carry out the above control.

As described above, in the steady running state, the engine speed is controlled along the so-called optimum fuel consumption line where the fuel consumption is the best. This is achieved by obtaining the target engine speed based on the target output based on the output demand and the map, and controlling the gear ratio of the continuously variable transmission 2 so as to be the target engine speed, as described above. To be done. However, such engine control is a control that prioritizes fuel consumption, and the output torque may not always be sufficiently large with respect to the required output amount. Therefore, the control device according to the present invention executes a control different from usual when the output required amount becomes larger than a predetermined value, such as when the accelerator pedal is depressed for acceleration.

FIG. 1 is a flow chart for explaining the control example. First, it is judged whether or not there is an acceleration request (step S1). This can be determined, for example, by whether or not the accelerator opening has increased. If the determination in step S1 is negative because there is no acceleration request, the process returns without performing any particular control. On the contrary, if an affirmative determination is made in step S1 due to the acceleration request, it is determined whether or not the output request amount is equal to or greater than a predetermined value, that is, whether or not the accelerator depression speed is high ( Step S2). In particular,
It is possible to detect the depression angle of the accelerator pedal with a sensor (not shown) and obtain the amount of change of the angle per time for determination.

If the determination in step S2 is affirmative, the variable valve timing mechanism (VVT) 8 controls the advance of the intake valve 6 (step S2).
3). This is a control for changing the state shown on the left side of FIG. 4 to the state shown on the right side. Therefore, the degree of pushing back the air sucked into the cylinder is reduced, so that the substantial intake amount is increased and the output torque of the engine 1 is increased.

Further, the gear ratio γ by the continuously variable transmission 2 is increased (step S4). That is, it is downshifted. As a result, the rotation speed of the engine 1 increases, and the engine output increases accordingly.

It is determined whether the engine output thus increased has reached the required output value (step S5).
When a negative determination is made in step S5, the process returns to step S4 to further increase the gear ratio γ and increase the engine speed (engine output). When the engine output is increased in this way to reach the required output value, an affirmative decision is made in step S5, in which case the operating state of the engine 1 is controlled so as to achieve the required output with optimum fuel economy ( Step S6). Specifically, the valve timing of the intake valve 6 is retarded, set to the timing shown on the left side of FIG. 4, and continuously variable so that the target engine speed can be obtained from the target output and the optimum fuel consumption map. The gear ratio γ of the machine 2 is controlled.

If the determination in step S2 is negative, that is, if there is an acceleration request but the rate of change of the accelerator opening is small and the output request amount is small,
In step S4, the increase control of the gear ratio γ is executed so as to downshift according to the required output amount. That is, when the output request amount is small, it is sufficient to maintain the optimum fuel consumption state and perform the gear shift, so that the advance control of the valve timing is not executed.

FIG. 2 shows changes in the operating point when the control shown in FIG. 1 is executed. FIG. 2 is a diagram showing operating points by the engine speed NE (horizontal axis) and engine torque (vertical axis). In a steady state where there is no acceleration request or a quasi-steady state where an acceleration request is small, The engine torque (engine load) and the rotation speed (gear ratio) are controlled so that the operating point is located on the optimum fuel consumption line (thick line in FIG. 2). The optimum fuel consumption line and the line showing the torque during the retard control of the valve timing (the line shown as the torque during the VVT retard in FIG. 2) substantially coincide with each other.

The state before the output demand increases, that is, the initial state before the acceleration demand, is shown by point P1 in FIG. 2. If the output demand exceeds a predetermined value in this state, first, the valve of the intake valve 6 is The timing is advanced, and as a result, the engine torque increases before the engine speed NE changes. The engine torque set in this way is shown in FIG.
In the example shown in, the torque is in the full load torque generation state (WOT). That is, in the example shown in FIG. 2, the line indicating the torque during the advance control of the valve timing (torque during the VVT advance in FIG. 2) coincides with the WOT line.

The operating point thus achieved is the point P2 in FIG. 2, and the engine torque does not increase any more unless the rotational speed changes, so the gear ratio γ of the continuously variable transmission 2 is increased.
The engine speed NE and the engine torque increase as the engine speed increases. The change in the operating point in this case is a change substantially along the line indicating the WOT state.

When the engine output increases due to the increase of the throttle opening and the change of the valve timing due to the increase of the required output amount and the increase of the gear ratio γ, the output finally becomes equal to the required output amount. This is indicated by point P3 in FIG. After that, the operating state of the engine 1 is changed toward the target operating point (point P4 in FIG. 2) on the optimum fuel consumption line. Specifically, this control is a control that changes the operating point along an equal output line showing the output that matches the output required amount, and the valve timing is retarded to the state shown on the left side of FIG. The gear ratio γ of the continuously variable transmission 2 is controlled so that the engine speed NE becomes a speed determined by the intersection of the equal output line and the optimum fuel consumption line.

Therefore, in the above-described control, when a large acceleration request (increase in the output request amount) is made, first, the valve timing is changed to the high output torque side to increase the engine torque, so that there is no control responsiveness. By being faster than the speed change response of the stepped transmission 2, the driving torque can be rapidly increased and an acceleration feeling can be obtained without causing a delay. Then, after the engine output is increased to the output based on the output required amount, the engine speed control by the continuously variable transmission 2 achieves the driving state in which the fuel consumption is improved, so that the fuel consumption can be improved. Alternatively, deterioration of fuel efficiency can be avoided or suppressed.

The relationship between the above-described specific example and the present invention will be briefly described. The functional means of steps S1 and S2 shown in FIG. 1 correspond to the output request determining means of the present invention.
The functional means of steps S3 and S4 correspond to the output increasing means of the present invention, and the functional means of step S6 correspond to the returning means of the present invention.

The present invention is not limited to the above specific examples. For example, in the above-described specific example, the valve timing is fully advanced in the range where knocking does not occur at full load, but similar valve timing control may be executed in a so-called medium / light load state. Further, although an example of advancing / retarding the opening / closing timing of the intake valve has been shown as the control for changing the operating state of the valve, the control for changing the operating state of the valve in the present invention is essentially a matter of substantially reducing the intake air amount. It suffices that the control can be changed. Therefore, control that changes the opening / closing timing with an electromagnetically driven valve that can individually control each valve or control that changes the intake air amount by changing the valve lift amount may be used.

Further, in the above-mentioned specific example, an example is shown in which the engine output is increased to the target output and then the engine output is controlled so as to shift to the target operating point on the optimum fuel consumption line. It may be controlled so as to shift from a state that does not completely match the target output to a target operating point on the optimum fuel consumption line, and the statement that "the running state of the vehicle has reached a predetermined state" in claim 1. And claim 4
The description of "the predetermined output has been reached based on the output request amount" in 1 is meant to include such control. Further, in the above specific example, a vehicle equipped with a so-called high expansion ratio engine has been described as an example, but in the present invention, the point is that an internal combustion engine capable of changing the operating state of the valve is required. The internal combustion engine is not limited to a high expansion ratio engine.

[0037]

As described above, according to the first aspect of the present invention, the drive torque rapidly increases as the output torque of the internal combustion engine increases, and the driving torque increases as the rotational speed of the internal combustion engine increases. Since the output increases, it is possible to obtain the acceleration performance according to the output demand, and, after the running state of the vehicle reaches a predetermined state by increasing the output of the internal combustion engine,
Since the operating state of the intake valve and the gear ratio of the continuously variable transmission are controlled in a state set in consideration of fuel consumption, both acceleration responsiveness and fuel consumption can be improved.

Further, according to the second aspect of the present invention, in normal times, the internal combustion engine is operated at a relatively high expansion ratio to improve fuel efficiency, and when the output demand is large, the expansion ratio is relatively high. Since the output torque is increased as well as the output torque is reduced, both the acceleration response and the fuel consumption can be improved, as in the first aspect of the invention.

Further, according to the third aspect of the present invention, when the required output amount is increased, the output torque of the internal combustion engine is increased to the limit, so that the acceleration response can be improved.

Further, according to the invention of claim 4, the output torque of the internal combustion engine is increased by changing the operating state of the intake valve, and then the operating state is satisfied so that the output demand is satisfied with the optimum fuel consumption. As in the invention described above, both acceleration response and fuel economy can be made favorable.

[Brief description of drawings]

FIG. 1 is a flowchart showing a control example executed by a control device according to the present invention.

FIG. 2 is a diagram showing a change in an operating point when the control shown in FIG. 1 is executed.

FIG. 3 is a schematic diagram of a drive system including an engine and a continuously variable transmission of a vehicle targeted by the present invention.

FIG. 4 is a diagram showing the relationship between the closing timing of the intake valve and the engine load.

[Explanation of Codes] 1 ... Engine, 2 ... Continuously Variable Transmission, 6 ... Intake Valve,
7 ... Exhaust valve, 8 ... Variable valve timing mechanism,
9, 10 ... Electronic control device.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 13/02 F02D 13/02 J 41/10 320 41/10 320 F term (reference) 3D041 AA26 AA32 AB01 AC01 AC15 AC19 AD02 AD10 AD14 AD51 AE02 AE03 AE31 AF01 3G092 AA01 AA11 DA01 DA03 DA07 EC10 HA06Z HE01Z HE08Z HF08Z HF12X HF21Z 3G093 AA06 BA19 CA07 DA01 DA05 DA06 DB05 EB03 FA10 3G301 HA01 HA19 JA01 JA02 JA03 KA12 LA03 LA07 NA07 NC02 ND03 ND04 NE01 NE11 PA11Z PE01Z PE08Z PF01Z PF08Z

Claims (4)

[Claims] 1. An internal combustion engine in which the intake valve is controlled to a predetermined operating state based on fuel efficiency when the operating state of the intake valve can be changed and the required output amount is relatively small. In a control device for a vehicle to which a continuously variable transmission whose gear ratio is controlled so that the number of revolutions of the vehicle is a number of revolutions set in advance in consideration of fuel economy, the required output amount is not less than a predetermined value. Output request determining means for determining, and when the output request determining means determines that the output request amount is equal to or greater than a predetermined value, the operating state of the intake valve is controlled to a high output torque side, and Output increasing means for changing the gear ratio of the continuously variable transmission in a direction in which the rotational speed of the internal combustion engine increases, and the operating state of the intake valve and the gear ratio of the continuously variable transmission are controlled by the output increasing means, Vehicle running status After a predetermined state is reached, the operating state of the intake valve is controlled to a predetermined operating state based on the fuel efficiency, and the speed ratio of the continuously variable transmission is set to the fuel consumption rate of the internal combustion engine. A control device for a vehicle, comprising: return means for controlling to a speed ratio having a predetermined rotational speed in consideration of the above. 2. The output increasing means includes means for advancing the opening / closing timing of the intake valve when the output request determining means determines that the output request amount is greater than or equal to a predetermined value. The control device for a vehicle according to claim 1, wherein: 3. The output increasing means includes means for controlling an operating state of the intake valve to an operating state in which the torque of the internal combustion engine is increased to a full load torque generation state. Alternatively, the vehicle control device described in 2. 4. The return means, after the output of the internal combustion engine reaches a predetermined output based on the output required amount, sets the operating state of the intake valve to a state in which the output required amount is satisfied with optimum fuel consumption. 4. The vehicle control device according to claim 1, further comprising means for controlling a gear ratio of the continuously variable transmission.