JPS61187532A - Supercharge pressure controller - Google Patents

Abstract

PURPOSE:To always sufficiently increase the supercharge pressure during the sharp acceleration of a car by increasing the set supercharge pressure than the ordinary set value when each of the increasing speed and the magnitude of the accelerator opening-degree is over each set value. CONSTITUTION:A waist gate valve 20 restricts the number of revolution of a turbocharger 3 and suppresses the supercharge pressure to a certain value, and opens and closes a bypass passage 21 for connecting the upper and lower parts of a turbine wheel 4 in an exhaust passage 7. For instances, when the bypass passage 21 is opened, the amount of exhaust gas supplied into the turbine wheel 4 is reduced, and the supercharge pressure of the turbocharger 3 is restricted. In this case, a negative-pressure selector valve 29 which communicates to a diaphragm apparatus 22 for driving the above-described valve 20 is controlled by an electronic control part 40. When each value of the speed and the magnitude of the increase of the accelerator opening-degree which are detected by the sensors 50 and 51 is over each set value, the bypass passage 21 is closed to increase the set supercharge pressure over the ordinary set pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to a device for controlling boost pressure characteristics during acceleration in a diesel engine equipped with a turbocharger.

[Conventional technology]

2. Description of the Related Art Conventionally, engines equipped with a supercharger such as a turbocharger have been known in order to improve the output performance of the engine. However, in this type of engine, from the viewpoint of engine durability, a bypass passage that bypasses the exhaust turbine is formed in the exhaust system, and a waste gate valve is provided that opens this passage depending on the intake pressure. That is, it attempts to protect the engine by determining the upper limit value of boost pressure.

However, if the upper limit value of the boost pressure is fixed even when the engine is accelerating, which temporarily requires high output, a problem arises in that sufficient acceleration performance cannot be obtained. For this reason, in Japanese Patent Application Laid-Open No. 57-146023, when the engine accelerates,
A boost pressure control device has been proposed that is configured to make the maximum boost pressure higher than a normal set value for a predetermined period of time.

[Problem that the invention seeks to solve]

If the period during which the maximum boost pressure is increased above the normal set value is set constant as in the proposed device, a problem arises in that even if higher output is required, it cannot be obtained.

[Means for solving problems]

In order to solve the second problem, the supercharging pressure control device according to the present invention provides a supercharging pressure control device in which the accelerator opening increases at a rate equal to or higher than a set value,
The present invention is also characterized in that the set supercharging pressure is set higher than the normal set value when the accelerator opening is equal to or greater than the set opening.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an internal combustion engine to which a boost pressure control device according to an embodiment of the present invention is applied. In this figure, a turbocharger 3 that supercharges high-pressure air into a combustion chamber 2 formed in a cylinder 1 has a turbine wheel 4, a compressor wheel 5, and a shaft 6 connecting the centers of these wheels 4.5. and has. The turbine wheel 4 and the compressor wheel 5 are connected to an exhaust passage 7 and an intake passage 8 that communicate with the combustion chamber 2.
The shafts 6 and 6 rotate around the axis of the shaft 6, respectively. That is, the compressor wheel 5 rotates as the turbine wheel 4 is rotationally driven by the exhaust gas passing through the exhaust passage 7, and as a result, the air taken into the intake passage 8 from the atmosphere port 9 is made high pressure and flows into the combustion chamber. It is fed to the second side.

A throttle valve IO is provided in the middle of the intake passage 8,
Further, a fuel injection valve 11 is disposed downstream of the throttle valve 10 and near the combustion chamber 2.

The waste gate valve 20 limits the rotational speed of the turbocharger 3 and suppresses the boost pressure to a constant value.
A bypass passage 21 connecting the Il/A side of the turbine wheel 4 and the downstream side of the exhaust passage 7 is opened and closed. A diaphragm device 22 that opens and closes the waste gate valve 20 includes a shell 23, a pressure change chamber 24, a spring chamber 25, and a shell 23.
A diaphragm 26 partitioning the spring chamber 25 into a spring chamber 25 and a spring 27 provided within the spring chamber 25 are provided. The variable pressure chamber 24 is always in communication with the intake passage 8 via a passage 28, while the spring chamber 25 is connected to a negative pressure source 30 or the atmosphere via a negative pressure switching valve 29.

The rod 31 fixed to the diaphragm 26 is connected to the spring chamber 25
It projects to the outside of the shell 23 and is connected to a link 32 provided on the pipe wall forming the bypass passage 21 . This link 32 is coupled to the wastegate valve 20. When the pressure difference between the variable pressure chamber 24 and the spring chamber 25 overcomes the elastic force of the spring 27, the waste gate valve 20 opens the bypass passage 21, thereby causing the turbine wheel 4
The amount of exhaust gas supplied to the turbine wheel 4 is reduced, the rotation of the turbine wheel 4 is suppressed, and the supercharging pressure of the turbocharger is limited.

The f1 pressure switching valve 29 and the fuel injection valve 11 are controlled by an electronic control section 40 consisting of a microcomputer.

The electronic control unit 40 includes a central processing unit (CPIJ) 41,
Random access memory (RAM) 42, read only memory (ROM) 43, input/output port (I10 port) 44, and a path line 45 that interconnects these
Equipped with. The I10 port 44 is connected not only to the negative pressure switching valve 29 and the fuel injection valve 11 but also to an accelerator sensor 50 and a rotation speed sensor 51.

The accelerator sensor 50 has a potentiometer (not shown) that detects the rotation angle of the support shaft of the accelerator pedal, and its output signal is A/D converted and input to the I10 boat 44. The rotational speed sensor 51 is connected to a crankshaft (not shown) and measures the rotational speed of the crankshaft, that is, the engine rotational speed, and its output pulse signal is shaped into a waveform and input manually to the I10 port 44. .

The electronic control unit 40 calculates the fuel injection amount and the upper limit value of the supercharging pressure according to the flowchart shown in FIG. 2, and controls the fuel injection valve 11 and the negative pressure switching valve 29. Step 10
At 0, the ROM is calculated from the engine speed and accelerator opening.
Using, for example, a map stored in 43, the fuel injection amount and boost pressure under normal conditions are calculated. The normal value calculated in this case is the valve opening time of the fuel injection valve 11 and the pressure in the spring chamber 25 of the diaphragm device 22, that is, the valve opening of the negative pressure switching valve 29, except when the engine is suddenly accelerated. The negative pressure switching valve 29 corresponds to the spring chamber 25.
is controlled so as to communicate only with the negative pressure source 30. Next, in step 101, the acceleration state is calculated from the change in accelerator opening, that is, the speed of increase. In other words, in step 101, it is detected whether the driver is trying to rapidly accelerate the vehicle by pressing down on the accelerator pedal. If you are trying to accelerate suddenly, step 1
11 is determined in step 02 and the next step 103.1
04.105 is executed, and if rapid acceleration is not intended, a negative determination is made in step 102, and step 106 is then executed.

When the process moves from step 102 to step 106, for example, the vehicle is traveling steadily, and in step 106, the fuel injection amount and boost pressure are set to steady values. That is, the start time of the fuel injection valve 11 is set based on the normal value determined in step lOO, and the negative pressure switching valve 29 conducts only the negative pressure a30 to the spring chamber 25 of the diaphragm device 22.

When the process moves from step 102 to step 103, the vehicle is about to suddenly accelerate, and in step 103, the time at that time, that is, the acceleration start time t.

is loaded. Next, in step 104, a set value of the boost pressure corresponding to the elapsed time from the acceleration start time to is calculated. As shown in FIG. 3, this calculated value of supercharging pressure increases as the accelerator opening increases, and is equal to the supercharging pressure (indicated by the broken line) when step 104 is not executed. It's big in comparison. At this time, the negative pressure switching valve 29 becomes partially connected to the atmosphere, and as a result, the spring chamber 2
The pressure inside 5 has become high, making it difficult to open the waste gate valve 20.

In step 105, it is determined whether the accelerator opening degree is greater than a set value. The set value here is a value close to fully open. If the accelerator opening is larger than the set value, step 104 is executed again, and the set value of the supercharging pressure corresponding to the elapsed time from the acceleration start time to is calculated. When steps 105 and 104 are repeatedly executed, the supercharging pressure gradually increases until it reaches a predetermined value (indicated by 8 in the figure). Thereafter, when the accelerator opening becomes smaller than the set value, the process moves from step 105 to step 106, and the set value of the boost pressure is set to a steady value. In this case, the negative pressure switching valve 29 does not immediately shut off the atmosphere, but gradually shuts off the atmosphere. Therefore, the set value of the supercharging pressure gradually decreases as shown by B in the figure, so that the operating condition of the engine does not change rapidly, and deterioration of the engine durability is prevented.

FIG. 4 shows another embodiment of control by the electronic control section 40. In this flowchart, steps corresponding to those in FIG. 2 are indicated by adding 100 to the reference number of each step in FIG. The difference between the control shown in FIG. 4 and the control shown in FIG. 2 is step 207. In other words, in this embodiment, during sudden acceleration, in addition to increasing the set value of the supercharging pressure, the amount of fuel injection is also increased. Figure 5 shows the changes in boost pressure and fuel injection amount as the accelerator opening changes.As can be seen from this figure, during sudden acceleration, the fuel injection amount changes in the same way as the boost pressure. do.

Note that the present invention can also be applied to a supercharger other than a turbocharger, such as a roots pump.

〔Effect of the invention〕

As described above, the present invention is configured to change the upper limit value of the boost pressure depending on the state of the accelerator opening. Therefore, during rapid acceleration of the vehicle, the supercharging pressure can always be sufficiently increased, and sufficient output performance can be obtained.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an internal combustion engine to which an embodiment of the present invention is applied, Fig. 2 is a flowchart showing an example of control by an electronic control section, and Fig. 3 is a control based on the flowchart in Fig. 2. Figure 4 is a flowchart showing another example of control by the electronic control unit, and Figure 5 is based on the flowchart in Figure 4 (control is performed). It is a graph showing temporal changes in accelerator opening degree, boost pressure, and fuel injection amount when the above steps are carried out. 20... Waste gate valve, 29... Negative pressure switching valve, 50... Accelerator sensor.

Claims (1)

[Claims] 1. A supercharging pressure setting mechanism that controls a set supercharging pressure of a supercharger;
The supercharging pressure setting mechanism is equipped with an accelerator sensor that detects the magnitude and increasing speed of the accelerator opening from the position of the accelerator pedal, and the boost pressure setting mechanism is configured such that the increasing speed of the accelerator opening is equal to or higher than a set value, and the accelerator opening is higher than the accelerator opening. A supercharging pressure control device characterized in that when the magnitude of the opening is greater than or equal to the set opening degree, the set supercharging pressure is made higher than the normal set value. 2. The supercharging pressure setting mechanism increases the set supercharging pressure based on the accelerator opening, and then gradually returns the set supercharging pressure to the normal setting when the accelerator opening becomes smaller than the set opening. 2. The supercharging pressure control device according to claim 1, wherein the supercharging pressure control device returns the supercharging pressure to the normal value.