JPS628341Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle drive mechanism for an exhaust turbine.

BACKGROUND ART Conventionally, some supercharged engines with exhaust turbines have a nozzle area that is variable depending on the rotation speed.

FIG. 1 shows the configuration of a conventional supercharged engine with a variable nozzle area exhaust turbine.

Exhaust gas exiting the cylinder 11 passes through an exhaust pipe 12 and drives a variable nozzle area exhaust turbine 13 .

The blower 14 driven by the exhaust turbine 13 is
Atmospheric air is compressed to obtain high-pressure supply air, which is then supplied to the air supply pipe 15.

The nozzle area of the exhaust turbine is changed during engine operation by the nozzle drive mechanism 18 using the force of compressed air supplied from the air cylinder 16 through the electromagnetic three-way valve 17.

At this time, the electromagnetic three-way valve 17 is switched by the output of the controller 21 which receives the engine rotation speed input signal 20 from the engine rotation speed detector 19.

FIG. 2 shows a cross section of the variable nozzle area exhaust turbine and details of the nozzle drive mechanism. Exhaust gas flowing from the exhaust pipe enters a scroll 31 provided in the turbine casing 30, passes through a nozzle 32, drives a rotor 33, and is discharged from an outlet 34. Nozzle 3
2 is attached to the shaft 35 and rotated by a lever 40.

A rotating ring 43 having an arm 44 holds a lever pin 41 attached to the lever 40 in a lever pin groove 42, and is rotated by the arm 44 to drive the lever 40. Arm 44 is driven by air piston 50. Details of the drive section of the lever 40 are shown in FIG.

The arm 44 has a fork portion 45 at its tip, and holds in a pin groove 46 a piston 53 provided at the tip of a piston rod 52 attached to a piston 51 of an air piston 50. As a result,
When the piston 51 is driven by the force of compressed air supplied through the electromagnetic three-way valve 17, the arm 44 is driven by the movement of the piston pin 53 through the piston rod 52, and the rotating ring 43 is rotated.
The angle θ changes.

Accordingly, the lever 40 shown in FIG. 2 rotates, and the shaft 35 rotates.

The movement of the nozzle 32 at this time is shown in FIG.

Since the nozzle 32 rotates around the shaft 35, its angle α changes, and the nozzle area F _N formed between it and the adjacent nozzle changes.

FIG. 5 shows the performance of a conventional supercharged engine with a variable nozzle area exhaust turbine. The horizontal axis is the engine rotational speed N
It is. When the engine is at maximum N=N5, the nozzle area of the exhaust turbine is _FN4 , _which is the maximum.

When the engine speed decreases, the exhaust flow rate per unit time decreases, causing the pressure inside the exhaust pipe to decrease.
Charge pressure P shown with reduced exhaust turbine output
_S goes down.

As a result, the amount of air in the cylinder decreases and the smoke density R increases.

When the engine speed N further decreases to N=N3, the smoke density R approaches the allowable limit R _M. At this time, a signal from the engine rotation speed detector 19 shown in FIG. 1 causes the electromagnetic three-way valve 17 to
is opened, and compressed air is supplied to the air piston 50 shown in FIG.

Accordingly, the nozzle 32 shown in FIG. 4 rotates through the arm 44 and the rotating ring 43 in a direction in which α increases, and the nozzle area F _N becomes F _N =F as shown in FIG.
It becomes small as _N2 .

As a result, the pressure inside the exhaust pipe increases, the exhaust turbine output increases, the supply air pressure P _S increases, and the smoke concentration decreases accordingly.

When the engine speed N is further lowered, the supply pressure P _S decreases again, and the smoke density R increases.

Then, when N=N6, R reaches the allowable limit R _M , and when the rotational speed continues to decrease to N1, the smoke density exceeds R _M and reaches R _X.

For this reason, in the conventional supercharged engine with a variable nozzle area exhaust turbine, the amount of fuel injected into the cylinder is reduced at low rotational speeds below the rotational speed N6 to suppress the smoke concentration R to below the limit value _RM .

As shown in Figure 5, when the engine speed N is below N6, the amount of fuel injected into the cylinder is reduced.
The engine torque T decreases to T ₁ at N=N1. This results in a lack of low-speed torque, making the engine difficult to use.

Furthermore, even in a high rotational speed range (medium speed range) near N=N3, the smoke density R is close to the allowable limit R _M. For this reason, if the condition of the engine changes slightly due to aging, etc., the smoke concentration will immediately exceed the permissible limit _RM , resulting in a highly polluting engine with high smoke concentration.

Furthermore, exhaust gas with large pressure fluctuations flows into an exhaust turbine attached to the engine. That is, in FIG. 1, since the exhaust gas coming out of the cylinder 11 is in a pulsed form, the pressure inside the exhaust pipe 12 varies greatly periodically. As a result, periodically varying forces act on the nozzle 32 of the variable nozzle area exhaust turbine shown in FIGS. As shown in Figures 2 and 3, the force is applied to the lever 40 and the lever pin 4.
1 is further transmitted to the drive system such as the arm 44. For this reason, with a conventional continuous position control mechanism such as that shown in Japanese Patent Publication No. 53-35209, periodic forces cause periodic sliding, even if only slightly, resulting in the problem of wear and tear on various parts. occurs.

The present invention solves the above-mentioned conventional drawbacks, and aims to increase the low-speed torque of a supercharged engine with a variable nozzle area exhaust turbine, and to improve the smoke density in the middle speed range.

The above purpose is to provide a controller to which an engine rotational speed signal is input, two electromagnetic three-way valves to which an output signal of the controller is input, and a first and a first electromagnetic valve driven by fluid supplied by each electromagnetic three-way valve. a two-position hydraulic cylinder having an intermediate portion pivoted to the piston rod of the first fluid pressure cylinder, one end engaged with the piston rod of the second fluid pressure cylinder, and the other end linked to the variable nozzle; a lever engaged with the arm, the respective engagements between the one end and the piston rod of the second fluid pressure cylinder and the other end and the arm are formed by displacement absorbing means; The variable nozzle is actuated via the lever, which can be statically fixed in four positions by both fluid pressure cylinders, to narrow the nozzle area at the low speed side of the engine rotation speed, and to widen the nozzle area at the high speed side of the same engine rotation speed. This is achieved by configuring the device to be controlled in the direction.

The present invention can be applied to a supercharged engine with a variable nozzle area exhaust turbine.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 6 and 7. In FIGS. 1 to 5, the same reference numerals are given to the parts that have already been explained, and the explanation thereof will be omitted.

In the nozzle drive mechanism of the variable nozzle area exhaust turbine of the present invention shown in FIG. 6, in addition to the air piston 50 which is the first fluid pressure cylinder, there is another
Air pistons 55 are provided. The air piston 55 is supplied with compressed air from the air cylinder 16 through an electromagnetic three-way valve 70 which is operated in response to an output from the controller 21 .

Furthermore, the piston 5 in the air piston 50
One piston rod 52 has a fulcrum 54 at its tip, and a pin 61 at one end is inserted into a pin groove 46 which is a displacement absorbing means of a fork portion 45 at the tip of an arm 44 of a rotating ring 43, and a fork is attached to the other end. 62, and a pin groove 63 which is a displacement absorbing means.
An air piston 55, which is a second fluid pressure cylinder,
A lever 60 is provided to hold the pin 58 at the tip of the piston rod 57 of the piston 56. This displacement absorbing means in the link prevents the rod from becoming stiff and improves the wear resistance of the cylinder.

Next, the operation of the embodiment of the present invention will be explained.

In Figure 6, the maximum rotational speed of the engine is N=N5
At this time, the two air pistons 50, 55 are in the positions shown. At this time, the fulcrum 54 of the lever 60 is at the illustrated position X1, and the fork portion 62 is at the Y1 position.

As a result, the pin 61 of the lever 60 is moved to the Z4 position shown in the figure.
Since the rotation angle of the rotating ring 43 becomes θ, the nozzle area becomes the maximum, F _N =F _N4 , as shown in the upper part of FIG.

Note that the horizontal axis in FIG. 7 is the engine rotation speed N.

Next, when the engine speed decreases to N=N4,
In the controller 21 shown in FIG. 6, an electromagnetic three-way valve opens in response to an engine rotational speed input signal 20. As a result, the piston 56 of the air piston 55 moves, and the lever 6
The fork part 62 of 0 is in the Y2 position, and the pin 6
1 will be in position Z3. Accordingly, the rotation angle of the rotary ring 43 changes, and the nozzle area becomes F _N =F _N3 as shown in FIG. When the engine rotational speed further decreases to N=N3, the electromagnetic three-way valve 70 closes according to a command from the controller 21, the piston 56 of the air piston 55 returns to its original position, and the fork portion 62 of the lever 60 returns to the Y1 position. At the same time, the electromagnetic three-way valve 17 opens according to a command from the controller 21, and the movement of the piston 51 of the air piston 50 causes the fulcrum 54 of the lever 60 to move to
position.

As a result, the pin 61 is at position Z2 and the nozzle area becomes F _N =F _N2 .

Finally, when the engine speed decreases to N=N2, the controller 21 commands the solenoid three-way valve 7
0 opens, the piston 56 of the air piston 55 moves, and the fork portion 62 of the lever 60 moves to the Y2 position. As a result, the pin 61 of the lever 60 is Z1
, and the nozzle area becomes F _N =F _N1 .

As described above, when the engine speed is N4<NN5, the nozzle area of the exhaust turbine is the same as the conventional one shown in Fig. 5, as shown in Fig. 7, and the engine performance is also the same, but N3<NN5. When it decreases to NN4, the nozzle area is reduced to F _N =F _N3 .

As a result, the pressure inside the exhaust pipe increases and the exhaust turbine output increases, so the supply pressure P _S increases as shown in Figure 7, and the smoke concentration R also exceeds the allowable limit R _M at medium speeds near N≒N3. improved considerably.

Next, when N2<NN3, the nozzle area is the same as the conventional one, F _N =F _N2 , and the engine performance is also the same, but when N1<NN2, the nozzle area becomes F _N
=F Reduce to _N1 .

As a result, the supply air pressure P _S increases and the smoke concentration R
decreases, there is no need to reduce the amount of fuel injected into the cylinder even at rotational speed N=N1, and sufficient torque _Tx can be obtained. Therefore, it becomes an easy-to-use engine with low-speed torque.

Also, according to the present invention, the nozzle drive mechanism is divided into two
By statically fixing it using a position type fluid pressure cylinder, no sliding occurs even when periodic fluctuating force due to exhaust from the engine acts, and wear on the drive system can be prevented.

Furthermore, it has the advantage of adding one piston to the conventional system and being able to use the air cylinder as is, making it cheaper to construct than using other systems (servo mechanism, 3-position cylinder). It has remarkable effects such as

The first embodiment shown in FIG. 6 uses two air pistons that use compressed air, but other embodiments may use two hydraulic pistons instead of the air pistons. The device of the present invention is feasible.

All of these are piston mechanisms that can take two positions based on a command signal, and can be collectively referred to as two-position fluid pressure cylinders.

It goes without saying that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the gist of the present invention.

[Brief explanation of the drawing]

Figures 1 to 5 show the whole, parts, and performance of a conventional supercharged engine with a variable nozzle area exhaust turbine. The figure is a detailed diagram of the lever drive part, Figure 4 is a schematic diagram showing the movement of the nozzle, Figure 5 is a performance diagram against engine rotation speed, Figures 6 and 7 are
The figures show the nozzle moving mechanism of the variable nozzle area exhaust turbine of the present invention and its performance, FIG. 6 is a schematic diagram thereof, and FIG. 7 is a performance diagram with respect to engine rotation speed. 16...Air cylinder, 17,70...Solenoid three-way valve,
20... Engine rotation speed detector, 21... Controller, 43... Rotating ring, 44... Arm, 45... Fork portion, 46, 63... Pin groove, 50, 55... Air piston, 51, 56... Piston, 52, 5
7... Piston rod, 54... Fulcrum, 58, 61...
Pin, 60... lever, 45, 62... fork part.

Claims (1)

[Scope of utility model registration request] In a nozzle drive mechanism of a variable nozzle area exhaust turbine, a controller to which an engine rotational speed signal is input, two electromagnetic three-way valves to which an output signal of the controller is input, and fluid supplied by each electromagnetic three-way valve. first and second two-position hydraulic cylinders to be driven; an intermediate portion pivotally supported by the piston rod of the first hydraulic cylinder, and one end engaged with the piston rod of the second hydraulic cylinder; a lever engaged with an arm associated with the variable nozzle, and each engagement between the one end and the piston rod of the second fluid pressure cylinder and the other end and the arm is formed by displacement absorbing means. Further, the variable nozzle is moved in the direction of narrowing the nozzle area at the low speed side of the engine rotation speed through the lever which can be statically fixed at four positions by the first and second fluid pressure cylinders. A nozzle drive mechanism for an exhaust turbine, characterized in that the nozzle drive mechanism is configured to be controlled in a direction that increases the nozzle area on the high speed side.