JPS62182438A - Supercharger with variable nozzle - Google Patents

Abstract

PURPOSE:To enable reduction of a maximum value of a nozzle opening, by a method wherein a nozzle opening is controlled according to an engine back pressure on the turbine side and a boost pressure on the compressor side, and a turbine bypass passage is opened and closed by means of a boost pressure. CONSTITUTION:Since, in a partial load, there is no need to especially increase a boost pressure P3 by means of a controller 12, the opening of a nozzle 2 is set to a high value. During rapid acceleration and deceleration of all loads, not through control of the boost pressure, the opening of the nozzle is decided as the function of the number of revolutions of en engine, and except during rapid acceleration, the boost pressure is set to a high value according to the number of revolutions of an engine. In this case, when the boost pressure P3 exceeds a set value and the opening of the nozzle is below a set value, the nozzle 2 is opened by an actuator 6, and a control valve 37 is opened by an actuator 38 to open a bypass passage 36. Meanwhile, when the boost pressure P3 is below the set value, and by means of a difference or a ratio between a back pressure P4 and the boost pressure P3, the opening of the nozzle is controlled. This constitution enables prevention of reduction of the efficiency of a turbine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a variable nozzle supercharger that maintains the boost pressure (compressor outlet side pressure) of the variable nozzle supercharger at a constant value.

[Conventional technology]

Conventionally, devices for controlling the opening degree of the nozzle of a supercharger with a variable nozzle have been known (for example, Utility Model Application No. 58-111
Publication No. 324, Publication of Utility Model Application No. 5947229, Publication of Utility Model Application No. 5947229, Publication No. 1987
9-19928). In these variable nozzle superchargers, the opening degree of the nozzle is adjusted depending on the engine speed, and the area of the nozzle is accordingly varied.

Although not yet published, the applicant has also reported that the boost pressure of the compressor is directly controlled, and the nozzle opening is controlled to obtain the set boost pressure using parameters such as engine speed. A control method for a supercharger with a variable nozzle that is less susceptible to environmental changes in atmospheric pressure and atmospheric temperature has been proposed (Japanese Patent Application No. 15219/1983).
No. 2).

[Problem that the invention seeks to solve]

In a turbocharger with a variable nozzle, it is possible to obtain a specified boost pressure from a low speed range by narrowing the nozzle area, but if the nozzle area is narrowed too much, the efficiency of the supercharger decreases and engine back pressure increases significantly. There is a problem. Therefore, by controlling the movable range of the variable nozzle based on the relationship between boost pressure and engine back pressure, a sufficient supercharging effect can be obtained in the low speed range and engine performance can be improved.

In the high engine speed range, the nozzle of a supercharger with a variable nozzle opens wide, but if the nozzle opens too much, the efficiency of the turbine decreases, and the engine back pressure to obtain the specified boost pressure increases, resulting in engine performance. The problem is that it worsens the

The present invention improves turbine efficiency by minimizing the nozzle opening in the high-speed engine rotation range in a supercharger with a variable nozzle that controls the opening of the nozzle using engine back pressure and boost pressure. The purpose is to further improve engine performance.

[Means for solving problems]

A supercharger with a variable nozzle according to the present invention that meets this purpose detects engine back pressure on the turbine side and boost pressure on the compressor side, and controls the opening degree of the nozzle according to the engine back pressure and boost pressure. A supercharger with a variable nozzle according to the present invention, wherein the supercharger is provided with a bypass passage that bypasses the turbine, and the bypass passage is provided with a control valve that opens and closes the bypass passage depending on the boost pressure. consists of things.

(Function) In the variable nozzle supercharger configured in this way,
The boost pressure opens and closes the control valve in the bypass passage, thereby bypassing the exhaust gas.

As the engine speeds up, the nozzle opening increases, but if the nozzle opens too much, turbine efficiency decreases.
By restricting the opening degree of the nozzle to a certain upper limit and bypassing the exhaust gas by that amount, a decrease in turbine efficiency is prevented. Therefore, the boost pressure is always maintained at a predetermined value, improving engine performance.

〔Example〕

Preferred embodiments of the variable nozzle supercharger according to the present invention will be described below with reference to the drawings.

FIG. 2 shows a control system for a supercharger with a variable nozzle for a vehicle. Exhaust gas from the engine is throttled by the nozzle 2 to increase its flow velocity, flows into the turbine wheel 1, applies rotational force to the turbine wheel 1, and is discharged. The turbine wheel l drives a compressor impeller (not shown) fixed on the opposite side on the same axis. The impeller rotates to compress the air (boost pressure), and the pressurized air is supplied to the engine.

Since the amount of air changes with engine rotation, the throat width d of the nozzle 2 is changed in order to obtain a predetermined boost pressure or compressor outlet pressure.

-i, the throat width d is made smaller when the engine rotation is smaller, and the throat width d is made larger when the engine rotation is larger. All the nozzles 2 are connected via levers 3 to a nozzle drive ring 4 that rotates concentrically with the turbine shaft, and by moving the ring 4, the nozzle throat width d can be controlled. The ring 4 is connected via a rod 5 to a rod 6 of the actuator tough. The actuator 6 is supplied with oil from an oil supply a (engine oil pressure or power steering oil pressure in the case of a vehicle) and operates. When increasing the nozzle throat d, open valve 8 to supply oil into actuator chamber 9, open valve C to return the oil in actuator chamber 8, and move actuator piston 1o to the left in the figure. The ring 4 is rotated counterclockwise in the figure via the rod 6. To make the nozzle throat d smaller, open valves B and D, and open valve A.
, C and rotate ring 4 clockwise. The nozzle opening degree is detected by a detector 11 that detects the position of the rod 6.

The opening degree of the nozzle 2 is controlled based on the relationship between the boost pressure and the engine back pressure on the turbine side in order to improve the effect of the supercharger.

FIG. 1 shows a schematic diagram of an engine and a supercharger with a variable nozzle. In the figure, 1 indicates a turbine wheel, and a nozzle 2 is disposed on the outer periphery of the turbine wheel 1. The turbine housing 3o that houses the turbine wheel 1 has a hole 30a for detecting engine back pressure P4.
is provided, and the engine back pressure P4 is configured to be detected by a sensor (as shown).

Further, in the combination nose housing 34 in which the impeller 33 is housed, there is a hole 33a for detecting the boost pressure P3.
is provided, and the boost pressure P3 is determined by a sensor (path shown)
is configured to be detected by In addition, in the figure, 32 indicates an exhaust manifold, and 31 indicates an intake manifold. Further, 35 indicates the combustion chamber of the engine.

A bypass passage 36 that bypasses the turbine wheel is provided on the turbine side. That is, one side of the bypass passage 36 is connected to the upstream side of the turbine wheel 1, and the other side is connected to the downstream side of the turbine wheel I. The bypass passage 36 is provided with a control valve 37 that maintains the boost pressure P3 on the compressor side at a constant pressure. The control valve 37 includes a valve body 39 provided in the bypass passage 36 and an actuator 3 that drives the valve body 39.
It consists of 8. Boost pressure P3 is guided to the actuator 38, and the valve body 37 receives the boost pressure P3.
It opens and closes depending on the height of 3.

In Fig. 2, 12 indicates an electronic controller for the variable nozzle control '<W, and the electronic controller 12 has a boost pressure JP3 (or compressor outlet pressure)
, engine back pressure P4, engine rotation N, accelerator opening A
Electrical signals such as , nozzle opening degree etc. are input. These electrical signals open and close valves A, B, C, and D, and the boost pressure or compressor outlet pressure is controlled via the nozzle position of the variable nozzle.

In the low speed region of the engine, the nozzle throat width d is set to the minimum position, so if the engine speed increases while the throat width d remains at the minimum, it will enter the compressor surge region and the operation will become unstable.

Therefore, control is performed such that the nozzle throat d is increased to obtain the set boost pressure in the medium speed region. In other words, by selecting an operating line as close to the surge region as possible, maximum engine performance can be extracted. The high-speed rotation range is a region where engine output is suppressed due to engine durability, and the nozzle opening degree is controlled to maintain the set boost pressure or compressor outlet pressure.

When the engine suddenly accelerates or decelerates, the feedback control method controls the boost pressure or compressor outlet pressure to the set value, but the response of pressure control is slow, resulting in unstable operation and far from optimal control. Become. Therefore, when the engine suddenly accelerates or decelerates, which is determined based on the accelerator opening degree, the engine speed, and the derivative thereof, the actuator is controlled so that the nozzle position is set based on the engine speed.

Further, the opening degree control of the nozzle 2 is performed based on the relationship between the boost pressure P3 and the engine back pressure P4. That is, boost pressure P3 and engine back pressure P4 are
It is a parameter (variable) for opening degree control, and the boost pressure P3 and engine back pressure P4 are controlled by the electronic controller 12.
or boost pressure P3 and engine back pressure P4
The pressure ratio is calculated, and the opening degree of the nozzle 2 is controlled based on this calculated value.

If the above explanation is shown in a block diagram, it will be as follows.

FIG. 3 shows a block diagram of control by the electronic controller 12 described above. As shown in the figure, the controller 12 first stores an accelerator opening setting value AS, an engine rotational acceleration setting value NS, which are stored in advance in a block 13.
Call the nozzle opening setting value VS and differential pressure (P4-P3) S. Next, in block 14, the current accelerator opening A, engine rotation 9N, nozzle opening ■
, boost pressure or compressor outlet pressure P3, and engine back pressure P4. Then, in block 15, A≧A
S is calculated, and if A is greater than or equal to A3, that is, if the load is full, the process proceeds to block 16, and if AS is less than 8, that is, if the load is partial, the process proceeds to block 17.

At partial load, there is no need to particularly increase the boost pressure, so the nozzle opening (■) may be wide open.

Therefore, the process proceeds to block 17, where it is determined whether or not the nozzle opening degree ■ is equal to the relatively large nozzle opening setting value VS. If they are equal, the process returns to block 14; if they are not equal, the process proceeds to block 18. A,
B, C, and D are activated so that v=vS, that is, the nozzle opening degree ■ is widened, and the process returns to block 14.

When the process proceeds to block 16 with full load, the accelerator opening acceleration DA and the engine rotation speed acceleration DN are calculated. Next, the process proceeds to block 19, where it is determined whether or not sudden acceleration/deceleration is occurring. That is, the actual accelerator opening acceleration DA and the preset accelerator opening acceleration DAS are compared, and the DA
≧DAS or DN≧DNS is determined, and if YES, that is, when the acceleration speed is reached, proceed to block 20 and set the desired nozzle opening setting value SS to the engine rotation speed N.
, and switches to nozzle position control instead of boost pressure control. In other words, the nozzle opening degree ■ is ■SS
It is determined in block 21 whether or not it is equal to v.

When there is no rapid acceleration or deceleration, that is, when the condition is steady or close to steady, the process proceeds to block 23, where the boost pressure P3S or compressor outlet pressure that should be as a function of the engine speed N is calculated. This P3S is set to as high a boost pressure as possible from the perspective of not entering the compressor surge region when the engine speed is in the low to medium speed range.
In a region where the engine speed N is large, the set pressure is set to increase with the engine speed so that the boost pressure as large as possible can be obtained based on the conditions on the engine side.

That is, f (N) is a set pressure that is made as large as possible from the viewpoints of both the supercharger and the engine, and is the optimal set pressure. Next, proceed to block 24, and boost pressure P3
It is determined whether or not P3 is equal to a preset boost pressure P3S, that is, P3=P3S. If P3 is equal to P3S, the process proceeds to block 14, and if not, the process proceeds to block 26.

Boost pressure P3 is determined in block 24, and if boost pressure P3 is not equal to set value P3S, it is determined in block 26 whether boost pressure P3 is smaller than set value P3S.

If the boost pressure P3 is larger than the set value in block 26, the process proceeds to block 40, where the current opening degree of the nozzle 2 is compared with the set value vsss. Then, if the opening degree ■ of nozzle 2 has not reached the set value vsss, P3=P3
Block 2 to open nozzle 2 so that it becomes S.
Proceed to step 5 and actuate the actuator 6. When the current nozzle opening degree V is greater than or equal to the set value VSSS, the nozzle 2 is stopped and a decrease in turbine efficiency is prevented. The boost pressure P3 at this time is P3>P3S, and the control valve 37 operates at a pressure slightly higher than the boost pressure set value P3S.
The valve body 39 provided therein is brought into an open state by P3 guided by the actuator 38. That is, the control valve 37 is not opened within the variable range of the nozzle 2. Therefore, when P3>P3S, the exhaust gas discharged from the engine bypasses the turbine, and the boost pressure P3 is maintained at a predetermined value.

In block 26, if P3<P3S, P3 is compared with engine back pressure P4 in block 27. In the figure, P4
-P3, that is, the difference in pressure between the two is the set value (P4-P3
) compared with S. The quantity to be compared is the pressure ratio P
4/P3 may be compared to its set value. In block 27, (P4-P3)< (P4-P3)S
In this case, the engine back pressure P4 will not become too large and the engine performance will not deteriorate, so the process proceeds to block 25 and the actuator 6 is operated so that P3=P3S, that is, the nozzle 2 is closed.

Block 28 further compares P4-P3 and (
If P4-P3)-(P4-P3)S, the nozzle 2 is no longer closed and the process proceeds to the next step 14. (P
4-P3)# If (P4-P3)S, that is, if (P4-P3)> (P4-P3)S, engine back pressure P4 is too high and is reducing engine performance, so block At 29, the actuator 6 is actuated to open the nozzle 2, thereby reducing the engine back pressure P4.

〔Effect of the invention〕

As explained above, when using the variable nozzle supercharger of the present invention, the engine back pressure on the turbine side and the boost pressure on the compressor side are detected respectively, and the nozzle opening is adjusted according to the engine back pressure and boost pressure. The controlled supercharger with variable nozzle has a bypass passage that bypasses the turbine, and a control valve is installed in this bypass passage to bypass the exhaust gas, making it possible to reduce the maximum nozzle opening. This prevents the turbine efficiency from decreasing due to the nozzle opening too much. Therefore, the boost pressure is maintained at a constant value, resulting in the effect that engine performance in the high speed range can be improved.

Furthermore, since the variable range of the nozzle is reduced, the reliability of the nozzle movement under high temperatures can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a supercharger with a variable nozzle according to an embodiment of the present invention, Fig. 2 is a control system diagram of Fig. 1, and Fig. 3 is a control system diagram of the control system of the present invention. 1n block diagram.

Claims (1)

[Claims] (1) A supercharger with a variable nozzle that detects engine back pressure on the turbine side and boost pressure on the compressor side, and controls the opening degree of the nozzle according to the engine back pressure and boost pressure. The turbocharger is provided with a bypass passage that bypasses the turbine, and the bypass passage includes:
A supercharger with a variable nozzle, comprising a control valve that opens and closes a bypass passage according to the boost pressure.