JPS635117A - Turbine nozzle control method for supercharger - Google Patents

Abstract

PURPOSE:To prevent the reduction in the intake efficiency of an engine by bringing a turbine nozzle to the fully opened condition in a low load operating region so as to reduce the back pressure for the exhaust gases of the engine. CONSTITUTION:On the upstream side of a turbine part 14, a variable nozzle 3 consisting of a great number of vanes is provided, and the opening of the variable nozzle 3 is regulated by a regulating mechanism 4. The regulating mechanism 4 is controlled by an actuator 20, and the actuator 20 has a positive pressure chamber and a negative pressure chamber each of which is outlined by a diaphragm, and is connected to an intake passage 8 on the upstream side of a throttle valve 11 and to an intake passage 10 on the downstream side thereof via pipe lines 18, 19 having control valves 18a, 19a respectively. The variable nozzle 3 is freely controlled by using the control valves 18a, 19a in combination, thus the variable nozzle 3 is fully opened in a low load operating region, and the nozzle opening is reduced as the accelerator pedal is stepped-in.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a turbine nozzle control method for variable turbine nozzle type supercharging, and in particular to variable turbine nozzle control that can improve fuel efficiency in the partial load region of an engine. Regarding the method.

<Conventional technology> Conventionally, a type of pre-supercharging device called a turbocharger has been used for the purpose of increasing engine output, but this is especially true for vehicles where the operating load and operating speed range vary greatly, such as in vehicle engines. When supercharging the engine,
The problem was how to balance large supercharging capacity with quick response. Therefore, as disclosed in Japanese Patent Publication No. 39-7653 or Japanese Patent Application No. 60-111473, a variable nozzle having a movable vane is provided on the circumference of the upstream side of the exhaust turbine, and supercharging When it is desired to increase the effect, a technique has been proposed in which the flow velocity of the exhaust gas flowing into the exhaust turbine is increased by narrowing the nozzle to improve the supercharging effect as desired.

<Problems to be Solved by the Invention> In such a supercharger, the method of controlling the variable turbine nozzle poses a problem. Conventionally, supercharging is performed from a region where the engine speed is relatively low, and when the engine speed exceeds a predetermined value called the intercept point, the wastegate valve is opened and the boost pressure reaches a ceiling. The only way to do this was to avoid problems such as engine knocking.

Therefore, depending on the operating conditions, if supercharging is performed when the engine load is relatively low, fuel efficiency may actually be impaired.

In view of the problems of the prior art, the main object of the present invention is to provide a turbine nozzle control method for a variable turbine nozzle supercharger that can improve fuel efficiency.

<Means for Solving the Problems> According to the present invention, such an object is achieved by:
A method for controlling a turbine nozzle in a supercharger comprising a compressor driven by the exhaust turbine, and a variable turbine nozzle upstream of the exhaust turbine for controlling the inflow speed of exhaust gas into the exhaust turbine. The variable turbine nozzle opening degree is kept substantially fully open when the engine load is below a certain predetermined value, and when the engine load exceeds the predetermined value, the variable turbine nozzle opening degree is maintained substantially fully open. This is achieved by providing a method for controlling a turbine nozzle, which is characterized by appropriately adjusting the .

<Operation> As described above, by fully opening the turbine nozzle in the low-load operating range, the back pressure against the exhaust gas of the engine can be reduced, and a decrease in the intake efficiency of the engine can be prevented. Therefore, deterioration in fuel efficiency due to operation of the supercharger in a low speed range can be avoided.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 schematically shows a supercharging structure for an engine to which the present invention is applied. Intake air to be supplied to the engine 1 is sent from the air cleaner 5 through the intake passage 6 to the compressor section 7 of the supercharger 2 and is pressurized. It is supplied to the combustion chamber of the engine 1 via a passage 10.

A fuel injection valve 12 is provided in the intake passage 10 downstream of the throttle valve 11 . Exhaust gas from the engine 1 is supplied to the turbine section 11!1 of the supercharger 2 through the exhaust passage 13, and after releasing power for driving the compressor section 7, it passes through the exhaust passage 15 and the muffler 16. released into the atmosphere. A variable nozzle 3 consisting of a large number of annularly arranged vanes is provided on the upstream side of the turbine section 14. By adjusting the opening degree of the variable nozzle 3 with an adjustment mechanism 4, the turbine section The flow rate of exhaust gas flowing into 14 can be controlled.

The adjustment mechanism 4 is controlled by an actuator 20,
As will be described later, this actuator 20 has a positive pressure chamber and a negative pressure chamber defined by two diaphragms. It is connected to an intake passage 8 on the upstream side of the valve 11 and an intake passage 10 on the downstream side of the throttle valve 11. Furthermore, these control valves 18a and 19a are
The opening/closing is controlled by a control device 7 whose parameters are the engine rotational speed Ne and the throttle opening θth.

FIG. 2 shows an embodiment of the actuator for driving the vanes described above. In FIG. 2, the actuator 20 has a first tube shaped like a bottomed cylinder having a relatively large diameter opening.
An annular intermediate member 22 communicating with the casing 21 through openings with different diameters at both ends, and a bottomed cylindrical second casing 23 having openings with a relatively small diameter are connected to a negative pressure diaphragm 24 with a large diameter and a negative pressure diaphragm 24 with a small diameter. A positive pressure diaphragm 25 is sandwiched therebetween and superposed on each other, and each is integrally connected using screws 26.

Note that the reference numeral 22a is a breather hole for the inside of the intermediate member 22.

A guide boss 26 is fixedly installed on the inner surface of the bottom wall of the first casing 21, and guide holes that align with each other are bored in the center and bottom wall of the guide boss 26.
The rod 28 is slidably inserted and supported through the . The negative pressure diaphragm 24 is fixed to the end of the rod 28 inside the casing 21 via a retainer 29 arranged on both sides of the rod 28, and a rod extends through the negative pressure diaphragm 24 and protrudes toward the intermediate member. A connecting rod 30 is screwed into the threaded portion 28a at the tip.

A positive pressure diaphragm 25 is fixed to the free end of the connecting rod 30 using a nut 32 via retainers 31 arranged on both sides thereof. Further, a coil spring 33 is interposed between the negative pressure diaphragm 24 and the bottom wall of the first casing 21 so as to surround the guide boss 26, and constantly biases the rod 28 in the retracting direction.

Furthermore, a negative pressure introduction port 34 is provided at a proper location in the first casing 21, and a positive pressure introduction port 35 is provided at a proper location in the second casing 23.
are fitted respectively, and the negative pressure inlet 34 is connected to the control valve 19a.
The positive pressure introduction port 35 is connected to the intake passage 8 on the upstream side of the throttle valve 11 via a control valve 18a.

Next, the operation of this embodiment will be explained.

First, the variable nozzle 3 of the supercharger is opened with no pressure acting on the actuator 20, that is, with the rod 28 retracted.
The rod 28 and the adjustment mechanism 4 described above are adjusted so that the
Connect them. When the engine is operating at low load, the intake pressure on the downstream side of the throttle valve 11 is in the negative pressure region.
The inside of the negative pressure to 36 defined by the first casing 21 and the negative pressure diaphragm 24 becomes negative pressure, and the negative pressure diaphragm 24
As a result of the suction, the rod 28 is pushed out in a direction that opens the variable nozzle 3. When the throttle valve 11 is opened to accelerate from this state, the negative pressure decreases, and the rod 28 moves in a direction to close the variable nozzle 3.

Therefore, the exhaust flow rate is increased and suitable supercharging is performed. Next, when the vehicle shifts to constant speed running, the negative pressure increases again as the load decreases, and the variable nozzle 3 is opened.

When operating at a certain high speed, the intake pressure may become positive due to boost pressure, but by providing the control valve 19a in the negative pressure introduction path 19, when the intake pressure is in the positive pressure region, The operation of the negative pressure actuator can be canceled by introducing atmospheric pressure into the negative pressure to 36. Therefore,
In this case, the vane is closed by the biasing force of the coil spring 33, and the exhaust flow velocity to the turbine increases. However, if the boost pressure increases beyond a certain level, the positive pressure diaphragm 2
5 and the second casing 23, supercharging pressure is introduced into the positive pressure chamber 38, which pushes out the rod 28 and can open the variable nozzle 3. By coaxially connecting the positive and load diaphragms in this way, regardless of whether the intake pressure is positive or negative, by using the control valves 18a and 19a together,
The variable nozzle 3 is freely controlled to open and close).

Fig. 3 shows a control schedule for the nozzle opening of the tanibine section 14 of the supercharger 2 in response to the engine rotational speed and engine load. 71, and in a region where the engine load exceeds a predetermined value, that is, outside the shaded area, the nozzle opening degree is adjusted according to the target boost pressure according to the size of the load. ing. In the case of this example,
In the partial load range, the variable nozzle 3 remains fully open, but when the engine speed is relatively high, the nozzle begins to close when the engine load is relatively small. . Such control of the nozzle opening degree is preferably performed by map control using engine load and engine rotational speed as parameters.

Figure 4 shows the opening degree of the nozzle as the load increases and decreases in the low engine speed range. In the low engine load range, the variable nozzle 3 is fully opened, and as the accelerator pedal is depressed, The nozzle opening degree is made small to increase the supercharging effect in the initial stage of acceleration.

In this way, by opening the nozzle almost fully in the operating range where the load is below a predetermined value, the back pressure of exhaust gas is kept low, improving engine filling efficiency and resulting in lower fuel consumption. improves.

If you press the accelerator pedal to accelerate, the nozzle opening will be adjusted according to the load situation, increasing the back pressure against the exhaust gas and increasing the supercharging effect, increasing the engine output. .

Note that during steady running, the opening degree of the variable nozzle 3 is adjusted as appropriate depending on the load at that time.

<Effects of the Invention> As described above, according to the present invention, it is possible to obtain a supercharging effect as needed, and also to effectively avoid deterioration of fuel efficiency. The effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a supercharging structure to which a turbine nozzle control method according to the present invention is applied. FIG. 2 is a longitudinal sectional view showing details of the actuator not shown in FIG. 1. FIG. 3 is a graph showing the opening degree of the variable turbine nozzle of the supercharger with respect to engine rotational speed and engine load. FIG. 4 is a graph showing the responsiveness of the turbine nozzle to the engine load at a certain engine speed. 1... Engine 2... Supercharger 3... Variable nozzle 4... Adjustment mechanism 5... Air cleaner
6...Intake passage 7...Compressor 8...
Intake passage 9...Intercooler 10...Intake passage 11...Throttle valve 12...Injection valve 13...
Exhaust passage 14...Turbine section 15...Exhaust passage 16...Muffler 17...Control device 1
8.19... Pipe lines 18a, 19a... Control valve 20... Actuator 21... First casing 2
2... Intermediate member, 22a... Breath handling hole 23...
・Second casing 24...Negative pressure diaphragm 25...
・Positive pressure diaphragm 26...Guide boss 27...Seal material 28...
・Rod 28a... Threaded part 29... Retainer 30... Connection rod 31... Retainer
32... Nut 33... Coil spring 34...
・Negative pressure inlet 35...Positive pressure inlet 36...Negative pressure chamber 38...Positive pressure chamber Patent applicant: Honda Motor Co., Ltd. Representative: Patent attorney Yo Oshima - Figure 1, Q. Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] A supercharger comprising an exhaust turbine, a compressor driven by the exhaust turbine, and a variable turbine nozzle located upstream of the exhaust turbine and controlling the inflow speed of exhaust gas into the exhaust turbine. A method for controlling a turbine nozzle in an aircraft, wherein the variable turbine nozzle opening degree is kept substantially fully open when the engine load is below a certain predetermined value, and when the engine load exceeds the predetermined value. A method for controlling a turbine nozzle, characterized in that the opening degree of the variable turbine nozzle is adjusted as appropriate when the variable turbine nozzle is opened.