JPH0525010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a turbocharger for an automobile.

[Prior art] Automotive turbocharged engines generally use exhaust energy to supercharge intake air to improve engine torque. In this case, supercharging pressure (positive pressure) is specified to prevent engine damage. An exhaust bypass mechanism is provided to prevent the pressure from rising above the specified value, and the actuator to which the supercharging pressure is guided opens the bypass valve (swing type wastegate valve) to bypass the exhaust gas.

In addition to the exhaust bypass mechanism, some vehicles are equipped with a mechanism for temporarily increasing the maximum boost pressure during acceleration to improve acceleration performance. In this case, by operating a solenoid valve provided in a conduit through which supercharging pressure is guided to an actuator, the conduit is opened and intake air is released to the atmosphere, thereby increasing the supercharging pressure at which the bypass valve can be opened.

The solenoid valve receives a signal from the control unit.
It operates by so-called duty control based on the ON/OFF ratio, and this control is easily realized by feedback control using boost pressure detection means using a microcomputer for controlling the engine, as known from Japanese Patent Application Laid-open No. 156435/1983. can.

However, in such conventional turbocharger control devices, the acceleration determination means that sends a signal to the control unit to operate the solenoid valve and increase the boost pressure during acceleration uses a full accelerator signal. There was a problem in that the so-called overboost function, which increases the maximum boost pressure only during acceleration, was activated, and overboosting was not possible during partial acceleration, making it impossible to improve acceleration performance.
Furthermore, since it is necessary to provide a full-open switch to determine when full-open acceleration is occurring, there is a problem in that the number of parts increases accordingly, resulting in an increase in cost.

[Object of the Invention] The present invention was devised in view of the above conventional problems, and provides a turbocharger control that enables accurate overboost control even during partial acceleration without using special parts. The purpose is to provide equipment.

[Structure of the Invention] In order to achieve the above object, the present invention, as shown in FIG. means, an overboost mechanism for temporarily increasing a target maximum boost pressure of the boost pressure, and an overboost mechanism for temporarily increasing the target maximum boost pressure of the boost pressure, and an increase amount of the boost pressure for acceleration determination corresponding to the gear ratio detected by the gear ratio detection means. a first calculation means for determining the amount of increase in the actual supercharging pressure detected by the boost pressure detection means within a predetermined time; and a supercharging pressure determined by the second calculation means. When the amount of increase within a predetermined period of time exceeds the amount of increase in boost pressure for acceleration determination determined by the first calculation means, it is determined that the vehicle is in an accelerating state and the overboost mechanism is activated. The configuration includes boost control means.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an outline of a turbocharged engine. According to this, an intake pipe 3 and an exhaust pipe 5 are connected to the engine body 1. A throttle valve 7 is provided in the intake pipe 3 near the engine main body 1, and a relief valve 9 and an air flow meter 11 are further provided upstream thereof (on the opposite side from the engine main body 1). A compressor 13 is installed in the intake pipe 3 between the air flow meter 11 and the relief valve 9, and a turbine 15 is installed in the exhaust pipe 5.
3 and the turbine 15 are interlocked and connected by a connecting shaft 17 to constitute a turbocharger.

The exhaust pipe 5 between the engine body 1 and the turbine 15 is provided with an exhaust bypass passage 19 that bypasses the turbine 15. The exhaust pipe 5 is provided with an exhaust bypass passage 19 that bypasses the turbine 15. A bypass mechanism 21 is provided. In the exhaust bypass mechanism 21, one end of a rod 27 is connected via a link mechanism 25 to an exhaust bypass valve 23 that opens and closes the exhaust bypass passage 19. That is, when the rod 27 moves to the right in FIG.
It is a mechanism that moves in the direction of opening.

The other end of the rod 27 is connected to a diaphragm 31 of the actuator 29.
1, the inside of the actuator 29 is divided into an atmospheric pressure chamber 33 on the right side and a positive pressure chamber 35 on the left side. Inside this atmospheric pressure chamber 33 is a spring 3 that urges the diaphragm 31 toward the positive pressure chamber 35.
7 is loaded. Further, the positive pressure chamber 35 and the outlet portion 39 of the compressor 13 are connected to an orifice 41.
They are communicated through a conduit 43 in which is arranged. This conduit 43 has a control unit 45 configured with a microcomputer, for example, to turn it on and off.
A solenoid valve 47 is provided which can open and close the pipe line 43 by controlling the ratio of so-called duty control to release the intake air from the positive pressure chamber 35 to the atmosphere. When the electromagnetic valve 47 opens, the boost pressure supplied to the actuator 29 is released into the atmosphere, and the maximum boost pressure set by the exhaust bypass mechanism 21 increases. Therefore, this solenoid valve 47
and exhaust bypass mechanism 21 and actuator 2
9 constitutes an overboost mechanism that temporarily increases the target maximum boost pressure.

Further, the engine body 1 includes a rotation speed detection means 49 for detecting the engine rotation speed.
A supercharging pressure detection means 51 is provided in each of the intake pipes 3 on the side of the outlet portion 39 of the intake pipe 3 . Signals from these detection means 49, 51, air flow meter 11, and vehicle speed detection means 46 are input to a control unit 45. Note that the rotational speed detection means 49 and the vehicle speed detection means 46 constitute a gear ratio detection means. As gear ratio detection means,
It may be a device that directly detects the gear engagement position or shift lever position in the transmission.

As shown in FIG. 2, the control unit 45 receives input signals of the engine rotation speed N detected by the rotation speed detection means 49 and the vehicle speed V detected by the vehicle speed detection means 46, and calculates the engine rotation speed N and the vehicle speed V detected by the vehicle speed detection means 46. Each gear ratio is 1st speed (low gear) based on the ratio with vehicle speed V.
-Discrimination unit 101 that discriminates 5th gear (top gear)
and a measuring section 103 that receives a signal input of the supercharging pressure P detected by the supercharging pressure detection means 51 and measures the increase amount ΔP of the supercharging pressure P after a predetermined time from the time when the supercharging pressure exceeds the predetermined supercharging pressure. , an arithmetic unit 105 that calculates the amount of increase ΔPk in the boost pressure for acceleration determination corresponding to the gear ratio determined by the discrimination unit 101, and an increase amount ΔP in the actual boost pressure P determined by the measurement unit 103; and the arithmetic unit 10
The comparison unit 107 compares the increase amount ΔPk of the boost pressure for acceleration determination obtained in step 5 and outputs an acceleration determination signal based on the difference as an acceleration determination signal.

The determination unit 101 and the calculation unit 105 determine the increase amount ΔPk of the boost pressure for acceleration determination corresponding to the gear ratio.
The measuring unit 103 constitutes a second calculating means for calculating the increase amount ΔP of the supercharging pressure P within a predetermined time, and the comparing unit 107
compares the amount of increase in supercharging pressure △Pk for acceleration determination with the amount of increase in actual supercharging pressure △P, and when △P exceeds △Pk (△P≧△Pk), the vehicle is in an accelerating state. This constitutes an overboost control means that determines that the overboost is present and activates the overboost mechanism.

Next, the effect will be explained.

First, when the engine starts operating, the engine body 1
The exhaust gas discharged from the engine reaches the turbine 15 through the exhaust pipe 5, and the turbocharger is activated. When the turbocharger operates, the pressure at the outlet 39 of the compressor 13, that is, the supercharging pressure increases, so that the pressure in the positive pressure chamber 35 of the actuator 29 also increases via the conduit 43. When the pressure in the positive pressure chamber 35 that has increased in this manner reaches a predetermined pressure, the exhaust bypass valve 23 opens due to the balance with the spring 37 loaded in the actuator 29, and the exhaust gas is bypassed. (The supercharging pressure at this time is the target maximum supercharging pressure.) Next, the action during acceleration will be explained based on FIG. If acceleration is started at a point in the diagram, the supercharging pressure will instantly rise to the atmospheric pressure at the point. The supercharging pressure that has reached atmospheric pressure in this way increases in accordance with each gear ratio. In FIG. 3, a solid line representing an increase in supercharging pressure at the third gear and the same solid line at the top gear show an increase in supercharging pressure during full throttle acceleration. Then, the supercharging pressure Pb at the point and the supercharging pressure Pc at the point after a predetermined time T ₁ have passed from this point are detected by the supercharging pressure detection means 51, respectively.
Each detected signal is sent to the control unit 45.
The measuring unit 103 shown in FIG. 2 measures the amount of increase in supercharging pressure ΔP (ΔP ₃ for third gear 3 and ΔP 5 for top gear ₅ ) after a predetermined time T ₁ has elapsed from the point.

On the other hand, the engine rotation speed N and vehicle speed V signals detected by the rotation speed detection means 49 and vehicle speed detection means 46 shown in FIG. be done. Once the gear ratio is determined, the calculation unit 105
Then, the increase amount ΔPk of the boost pressure for acceleration determination corresponding to this gear ratio is looked up. This △Pk is
A predetermined value is determined by experiment for each gear ratio.

The comparator 107 compares this boost pressure increase amount ΔPk for acceleration determination with the boost pressure increase amount ΔP, determines the acceleration state, and outputs an acceleration determination signal J. control the duty. In the acceleration state, the pipe line 43 is opened as appropriate by this duty control, and the intake air guided to the positive pressure chamber 35 side is released to the atmosphere, thereby increasing the supercharging pressure that can open the exhaust bypass valve 23. Since boost control is possible, acceleration performance is good. In this case, a full-open switch for the throttle valve 7 for detecting the full-open acceleration state is not required, so the number of parts can be reduced accordingly, and costs can be reduced. In addition, Pset in FIG. 3 indicates the target maximum boost pressure, and Psetθ indicates the maximum boost pressure when overboost control is performed.

FIG. 4 is a flowchart for performing the above operation processing. That is, in step 201, the gear ratio is determined directly from the engine speed and vehicle speed or from the gear position, and this is defined as POSG. In step 203, the increase amount △Pk of the boost pressure for acceleration determination is determined using this POSG. next step
In step 205, the increase amount △Pk of the boost pressure for acceleration determination obtained in step 203 is compared with the increase amount △P of the boost pressure in a predetermined time during acceleration, and △P≧△ is determined.
If it is Pk, that is, the acceleration state, the process advances to step 207 where KFLAG=1 is defined, and if ΔP<ΔPk, that is, it is not the acceleration state, the process advances to step 209 where KFLAG=0 is defined. Then, in the next step 211, either KFLAG=1 or KFLAG=
It is determined whether or not KFLAG is 0. If KFLAG=1, the process proceeds to step 213 and overboost control is performed to improve acceleration performance, and if KFLAG=0, overboost control is not performed.

Although the acceleration state cannot be determined at the start of acceleration, it can be sufficiently determined by the time the actual boost pressure reaches the target boost pressure Pset set by the exhaust bypass mechanism 21. After this determination, the solenoid valve 47 is operated by duty control to delay the opening timing of the exhaust bypass valve 23, and as a result, the supercharging pressure Pset rises, and for a certain period of time.
Overboost control that maintains the supercharging pressure Psetθ during T ₂ can be easily realized.

Further, during partial acceleration in the top gear, that is, during slow acceleration, the boost pressure rises more slowly, as shown by the broken line in FIG. 3, than in the solid line during full-throttle acceleration. During this partial acceleration, the acceleration state can be determined in the same manner as during full-throttle acceleration by using the amount of increase ΔP ₅₀ in the supercharging pressure P during the predetermined time T ₁ . Therefore, even during this partial acceleration, the amount of increase in the actual boost pressure △P is not set unambiguously, but is changed appropriately according to the operating condition, even in the top gear and other gear ratios. Control becomes possible and acceleration performance can be improved.

Note that this invention is not limited to the above-described embodiments. For example, in the above embodiment, an exhaust bypass mechanism was used as a mechanism to control the exhaust capacity to the turbine, but instead of this exhaust bypass mechanism, the area of the exhaust inflow passage to the turbine is changed by a variable nozzle to control the exhaust capacity. A variable displacement mechanism may be used, or a turbocharger may be provided with both this variable displacement mechanism and an exhaust bypass mechanism.

[Effects of the Invention] As described above, according to the present invention, acceleration is achieved by comparing the amount of increase in boost pressure for acceleration determination corresponding to the gear ratio with the amount of increase in boost pressure within a predetermined time. Since the overboost function can be activated accurately by determining the state, it is possible to determine whether the vehicle is accelerating not only during full-throttle acceleration but also during partial acceleration, so no matter what the acceleration state is. Acceleration performance can be improved. Further, conventionally, a full-open switch was required to determine when full-open acceleration was occurring, but this invention eliminates the need for a full-open switch, so the number of separate parts can be reduced and costs can be lowered.

[Brief explanation of drawings]

The attached drawings show one embodiment of the present invention, and FIG. 1 is an overall configuration diagram of a turbocharged engine, FIG. 2 is a block diagram showing the internal configuration of the control unit shown in FIG. 1, and FIG. 3 is a diagram showing the operation during acceleration. 4 is a flowchart, and FIG. 5 is a complaint correspondence diagram. (Explanation of symbols representing main parts of drawings), 21...
…Exhaust bypass mechanism (overboost mechanism),
29...actuator (overboost mechanism), 46...vehicle speed detection means (gear ratio detection means),
47... Solenoid valve (overboost mechanism), 49
...Rotational speed detection means (gear ratio detection means), 51...
...Supercharging pressure detection means, 101...Discrimination section (first calculation means), 103...Measurement section (second calculation means), 10
5... Calculating section (first calculating means), 107... Comparing section (overboost control means).

Claims (1)

[Claims] 1 supercharging pressure detection means for detecting the supercharging pressure due to turbocharging, gear ratio detection means for detecting the gear ratio of the transmission, and overboost for temporarily increasing the target maximum supercharging pressure of the supercharging pressure. a mechanism, a first calculation means for determining an amount of increase in boost pressure for acceleration determination corresponding to the gear ratio detected by the gear ratio detection means, and a first calculation means for calculating an increase in boost pressure for acceleration determination corresponding to the gear ratio detected by the gear ratio detection means; a second calculating means for calculating the amount of increase in the boost pressure within the predetermined time;
An automobile characterized in that it has overboost control means that determines that the vehicle is in an accelerating state and operates the overboost mechanism when the amount of increase in supercharging pressure for acceleration determination determined by the calculation means is exceeded. Turbocharger control device.