JPH0121142Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is used as a boost pressure control device for a vehicle engine equipped with a turbocharger.

(Prior Art and its Problems) The torque characteristics of a turbocharged vehicle engine at full load generally tend to increase rapidly near the point where the turbocharger begins to work effectively, as shown by A in FIG. When the shift position of the vehicle is at a low speed shift position such as first gear, there is a problem in that the tires slip due to a sudden increase in torque, causing tire spin, which impairs steering stability.

In order to solve this problem,
Publication No. 167928 states that when the shift position is at the low speed shift position, the set supercharging pressure is set to a low value (see Figure 3).
(see B'), suppresses the torque generated by the engine, and
As shown by B in the figure, the tire spin generation torque T ₀
A prior art configured as follows is disclosed.

By the way, as shown in Fig. 2, the relationship between the generated torque of the engine and the engine speed reaches its maximum at around engine speed _N1 , maintains the maximum torque until around engine speed _N2 , and then decreases to the engine speed. _N2
After that, the torque suddenly decreases. Therefore, according to the above-mentioned prior art, there is a problem in that the generated torque in a range exceeding around the rotational speed _N2 is significantly lower than in the general case.

(Purpose of the invention) The purpose of the invention is to solve the problems of the prior art described above.

(Structure of the invention) In order to achieve the above object, the present invention provides a supercharging pressure control device for a vehicle engine that controls supercharging pressure by opening and closing a waste gate or an intake relief gate of a turbocharger. The gate opening/closing means adjusts the opening/closing of the gate, and when the shift position is at the low speed position, the gate opening/closing means adjusts the set supercharging pressure of the intake system to the standard set value until the vehicle speed or engine speed reaches a predetermined value. The boost pressure is controlled to be lower than the boost pressure, and when the vehicle speed or engine rotational speed exceeds a predetermined value, the set boost pressure is operated to substantially match the standard boost pressure setting. Boost pressure control device for vehicle engines.

(Example) The present invention will be specifically described below based on an example shown in the drawings.

FIG. 1 shows a system for controlling supercharging pressure by opening and closing a wastegate 2 in a vehicle engine equipped with a turbocharger 1. As shown in FIG. The intake system of the engine includes a supercharging blower 7, a surge tank 8, and a carburetor 9 of the turbocharger 1, and the exhaust system of the engine includes an exhaust turbine 10 of the turbocharger 1, and an exhaust turbine 10 of the turbocharger 1. An exhaust bypass passage 11 is provided to bypass the exhaust gas.

The waste gate 2 of the exhaust bypass passage 11 is
It is opened and closed by a wastegate valve 13 driven by a diaphragm actuator 12.
Supercharging pressure downstream of the supercharging blower 7 is introduced into the pressure chamber 14 of the actuator 12 through a supercharging pressure introduction passage 15 . When the pressure introduced into the pressure chamber 14 exceeds a predetermined pressure, the waste gate valve 13 is opened and a part of the exhaust gas is guided to the exhaust bypass passage 11 through the waste gate 2, and the exhaust gas is introduced into the exhaust turbine 10. By suppressing the output of the engine, the supercharging pressure of the intake system is prevented from rising above a predetermined set supercharging pressure.

A controller 6a is provided in the boost pressure introduction passage 15.
A leak valve 6b controlled by is provided. The leak valve 6b is composed of a solenoid valve connected to three points: an atmosphere release pipe 16, an upstream pipe 15a of the supercharging pressure introduction passage 15, and a downstream pipe 15b thereof, and is introduced through the upstream pipe 15a. The supercharged air is configured to be able to leak to the atmosphere through an atmosphere opening pipe 16. The amount of air leakage is determined by the controller 6a from the leak valve 6b.
It is adjusted by controlling the ON/OFF ratio (duty ratio). Therefore, since the reduction ratio f is determined by the amount of leakage, the pressure in the pressure chamber 14 is
P ₁ is expressed as the following equation in relation to the supercharging pressure P of the intake system.

P ₁ ≒ (1-f) P If the pressure in the pressure chamber 14 required for the waste gate valve 13 to open is P ₁₀ , then the intake system A
The set supercharging pressure P ₀ is expressed by the following formula.

P ₀ ≒ P ₁₀ /(1-f)...(1) Since the above P is a constant, the above f is the control means 6 composed of the controller 6a and the leak valve 6b.
The set supercharging pressure P ₀ can be arbitrarily adjusted by controlling it by .

Detection data from an engine rotational speed sensor 4 that detects the engine rotational speed and a vehicle speed sensor 3a that detects the vehicle speed are input to the controller 6a. Based on these data, the leak valve 6
A control signal is output to the electromagnetic valve 6b to adjust the leakage amount and thus the pressure reduction ratio f by changing the ON/OFF ratio of the solenoid valve 6b.

Based on the vehicle speed data from the vehicle speed sensor 3a and the engine speed data from the engine speed sensor 4, the shift position is determined by the controller 6a, as is well known. That is, in this embodiment, the shift position detection means 3 for detecting the shift position is composed of a vehicle speed sensor 3a and an engine rotation speed sensor 4. Incidentally, as the shift position detecting means 3, it is also possible to employ a shift position detecting switch disposed in the transmission as in the above-mentioned prior art. Further, in this embodiment, an engine rotation speed sensor is used as the speed detection means 4, and the set supercharging pressure is controlled in relation to the engine rotation speed. It is also possible to configure the set supercharging pressure to be controlled in relation to the vehicle speed.

The control means 6 controls the pressure of the intake system when the gate opening/closing means 5 is opened, that is, the set supercharging pressure of the intake system, at the low speed shift position (for example, the first speed shift position) and at other shift positions. It is controlled differently in different cases. That is, when the shift position detection means 3 detects that the shift position is at the low speed shift position, the control means 6 controls the third shift position.
As shown by C' in the figure, the set boost pressure is changed to the standard set boost pressure (corresponding to A' in Figure 3) until the engine speed (vehicle speed data) reaches the predetermined rotation speed _N2 . When the engine rotational speed reaches a predetermined rotational speed _N2 or higher, the set supercharging pressure is controlled to substantially match the standard set supercharging pressure. Therefore, compared to the boost pressure control in the prior art shown by B' in _FIG . The boost pressure is increased, resulting in a higher pressure condition than in the prior art. Thereby, the output torque of the engine can be adjusted so as to gradually decrease even if the engine speed exceeds a predetermined speed _N2 , as shown by C in FIG.

In order to control the set supercharging pressure as shown in C' in FIG. 3, a map showing the relationship between the engine speed and the set supercharging pressure at the low speed shift position is stored in the memory section of the controller 6a. This can be done by outputting a signal to the leak valve 6b to control the reduction ratio f (which can be determined by the above equation (1)) based on this. However, in addition to this, as shown by the imaginary line in FIG. The configuration may be such that feedback control is performed by comparing the boost pressure with a target set supercharging pressure stored as . In this case, the leak valve 6
b and its control signal can be simplified.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, turbocharger 1
It is also possible to apply the present invention to a system in which boost pressure is controlled by opening and closing an intake relief gate instead of the waste gate 2 shown in FIG. Further, the gate opening/closing means 5 is not limited to one driven by the diaphragm actuator 12, and the gate valve itself can be directly driven by a solenoid. Furthermore, the present invention can also be applied to electronically controlled fuel injection vehicle engines.

(Effects of the invention) Since the present invention has the above configuration, it suppresses the increase in supercharging pressure and suppresses the engine output in the vehicle speed range (engine speed range) where tire spin is likely to occur at the low speed shift position. Then,
To improve steering stability by preventing tire spin, and to solve the problem of causing a sudden drop in torque when the vehicle speed (engine speed) exceeds a predetermined value, which is seen in the prior art. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the present invention, Fig. 2 is a graph showing the relationship between engine speed and torque, and Fig. 3 is a graph showing the relationship between engine speed and set boost pressure. . DESCRIPTION OF SYMBOLS 1... Turbocharger, 2... Waste gate, 3... Shift position detection means, 4... Speed detection means, 5... Gate opening/closing means, 6... Control means.

Claims (1)

[Scope of utility model registration request] A supercharging pressure control device for a vehicle engine that controls supercharging pressure by opening and closing a waste gate or an intake relief gate of a turbocharger, which comprises a gate opening/closing means for adjusting the opening/closing of the waste gate or intake relief gate. When the shift position of the opening/closing means is at the low speed position, the set boost pressure of the intake system is controlled to be lower than the standard set boost pressure until the vehicle speed or engine speed reaches a predetermined value, and the vehicle speed or engine speed reaches the predetermined value. A supercharging pressure control device for a vehicle engine, characterized in that the supercharging pressure control device for a vehicle engine operates to substantially match the set supercharging pressure with a standard set supercharging pressure when the supercharging pressure exceeds a predetermined value.