JPS6244097Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a turbocharged engine equipped with an exhaust turbocharger provided with a variable nozzle vane for adjusting the opening degree of a turbine nozzle.

Generally, an exhaust turbo supercharger consists of a turbine placed in the engine's exhaust passage and a compressor placed in the engine's intake passage. Therefore, the turbine is rotationally driven, and as the turbine rotates, a compressor mounted coaxially with the turbine is also rotationally driven, compressing the air flowing in the intake passage and supercharging it. By the way, a plurality of variable nozzle vanes are provided in the turbine nozzle of the turbine, and by opening and closing these variable nozzle vanes with an operating mechanism, the opening degree of the turbine nozzle can be set in three stages: a throttled state, an intermediate throttled state, and a fully open state. In addition, a rotation speed detector for detecting the engine rotation speed and a load detector for detecting the engine load are provided, and the engine rotation speed and engine speed detected by these rotation speed detectors and load detectors are installed. A configuration has been developed in which a variable nozzle vane is variably operated by an operating mechanism based on changes in load. In this case, in the low-speed rotation range until the engine speed reaches the first set value _N1 , the opening degree of the variable nozzle vane is held in the throttle state smaller than the intermediate throttle state, and the engine speed reaches the first set value N1. In the medium-speed rotation range between the set value _N1 and the second set value _N2 , which is higher than the first set value _N1 , the opening degree of the variable nozzle vane is maintained at an intermediate throttle state, and the engine speed is further increased. In the high-speed rotation range reaching the second set value _N2 or more, the opening degree of the variable nozzle vane is maintained at a fully open state, which is larger than the intermediate throttle state.

However, it is known that the boost pressure of the turbocharger discharged from the compressor of the exhaust turbosupercharger fluctuates significantly due to the influence of outside air temperature, and the boost pressure under the standard temperature state shown by the solid line in Figure 1 is Compared to this, as shown by the dashed line in the same figure, the boost pressure tends to increase during low temperature conditions such as winter, so there is a risk that the cylinder internal pressure will become excessive due to excessive boost pressure during low temperature conditions, causing engine damage. It was hot.

This idea was devised in consideration of the above circumstances, and its purpose is to provide turbo supercharging that reliably prevents damage to the engine body even when boost pressure fluctuates due to the influence of outside air temperature. The purpose is to provide engines.

An embodiment of this invention will be described below with reference to FIGS. 2 to 6. In FIG. 2, a represents the engine body, and b represents the exhaust turbo supercharger. This exhaust turbo supercharger b is formed of a turbine 1 disposed in an exhaust passage c of an engine body a, and a compressor e disposed in an air supply passage d. 1 is rotationally driven, and as the turbine 1 rotates, a compressor e mounted coaxially with the turbine 1 is rotationally driven, thereby increasing the filling efficiency of the air-fuel mixture supplied into the engine body a. Further, a variable nozzle vane 2 is disposed at a turbine nozzle (exhaust gas inlet) f of the turbine 1. As shown in FIG. 3, this variable nozzle vane 2 includes a movable ring 3,
It is formed by a plurality of movable vanes 4 and a plurality of connecting rods 5 that connect each movable vane 4 to the movable ring 3. Each of the movable vanes 4 is rotatably provided around a pin 6, and as the movable ring 3 rotates clockwise in FIG. 1, each movable vane 4 moves around a pin 6.
As the movable ring 3 rotates counterclockwise, each movable vane 4 is rotated counterclockwise around the pin 6. It's summery. Further, this variable nozzle vane 2 is adapted to be operated by an operating mechanism 7. The operating mechanism 7 is formed by a cylinder 8 as an actuator, first and second electromagnetic switching valves 9 and 10, and an air tank 11. Inside the cylinder 8, first and second pistons 12 and 13 are disposed, as well as first and second stoppers 14 and 15.
are provided for each. First stopper 14
is attached to an intermediate portion inside the cylinder 8, and first and second pressure chambers 16 and 17 are respectively formed inside the cylinder 8 by the first stopper 14. Further, the second stopper 15 is provided protrudingly from the end face on the second pressure chamber 17 side. Inside the first pressure chamber 16, a first piston 12,
A second piston 13 is located inside the second pressure chamber 17.
are placed respectively. Further, the piston rod 12a of the first piston 12 is inserted into the insertion hole 18 provided at the center of the first stopper 14.
The first piston 12 is guided by the first
The reciprocating motion is performed within the pressure chamber 17 of the cylinder. In addition, the piston rod 13a of the second piston 13 protrudes to the outside through an insertion hole 19 provided in the end face of the cylinder 8 on the second pressure chamber 17 side, and connects to the movable ring 3 through a connecting member 20.
is connected to. Also, this second piston 1
A coil spring 21 is wound around the piston rod 13a of No. 3. The second piston 13 is capable of reciprocating movement within the second pressure chamber 17 and is normally held pressed against the first stopper 14 by the biasing force of the coil spring 21. ing. Further, in the cylinder 8, a first vent hole 22 is formed in the end surface on the first pressure chamber 16 side, and a second vent hole 23 is formed in the peripheral wall surface on the second pressure chamber 17 side. And the first ventilation hole 22
has one end of the first air pipe 24 and a second ventilation hole 2.
3 are connected to one end of a second air pipe 25, respectively. Further, the other end of the first air supply pipe 24 is connected to a first electromagnetic switching valve 9, and the other end of the second air supply pipe 25 is connected to a second electromagnetic switching valve 10, respectively. Furthermore, the first electromagnetic switching valve 9 has an exhaust pipe 26.
and third air pipe 27, second electromagnetic switching valve 10
are connected to an exhaust pipe 28 and a fourth air supply pipe 29, respectively. Then, the first electromagnetic switching valve 9
, the first air pipe 24 and the exhaust pipe 26 are switched to a state in which they communicate with each other, or the first air pipe 24 and the third air pipe 27 are in communication with each other. The electromagnetic switching valve 10 switches between the second air pipe 25 and the exhaust pipe 28 and the second air pipe 25 and the fourth air pipe 29, respectively. It's getting old. Further, the third and fourth air supply pipes 27 and 29 are communicated with each other, and are supplied with air from the air tank 11, respectively. The first and second electromagnetic switching valves 9 and 10 are connected to each of the first and second air pipes 24,
25 and the exhaust pipes 26 and 28, respectively, the second piston 13 is moved to the reference position pressed against the first stopper 14 by the biasing force of the coil spring 21. It is starting to be retained. Further, the first solenoid valve 9 is switched to a state where the first air pipe 24 and the third air pipe 27 are in communication with each other, and the second electromagnetic switching valve 10 is switched between the second air pipe 25 and the exhaust pipe 27. When the switching operation is performed to communicate with the pipe 28, the air tank 11 is connected to the third and first air pipes 27, 24.
As shown in FIG. 4, the first piston 12 is pressed against the first stopper 14 by the air supplied into the first pressure chamber 16 through the
Piston rod 12a of this first piston 12
As a result, the second piston 13 is moved against the biasing force of the coil spring 21 and held at a first displacement position between the first and second stoppers 14 and 15. Further, each of the first and second electromagnetic switching valves 9 and 10 is connected to each of the first and second air pipes 24 and 25.
When the air tank 11 is switched to the state where the air supply pipes 27 and 29 are in communication with each other, the third and fourth air supply pipes 27 and 29 are connected to each other.
Since air is supplied into the first pressure chamber 16 via the fourth and second air supply pipes 29 and 25, air is also supplied into the second pressure chamber 17 via the fourth and second air supply pipes 29 and 25. As shown in FIG. 5, the second piston 13 is held at a second displacement position pressed against the second stopper 15. Therefore,
The second piston 13 can be moved to three stages: a reference position, a first displacement position, and a second displacement position based on switching operations of the first and second electromagnetic switching valves 9 and 10. When the second piston 13 is held at the reference position, the movable link 3 and each movable vane 4 are held in a fully open state in which the opening area of the turbine nozzle f of the turbine 1 is wide open, and the second piston 13 is held at the reference position. When the piston 13 is operated to move to the second displacement position, the second piston 1
3, the movable ring 3 is rotated clockwise in FIG. 1, and each movable vane 4 is
are rotated clockwise around pins 6, respectively, and held in a constricted state where the opening area of the turbine nozzle f of the turbine 1 is narrowed, and the second piston 13
is moved to the first displacement position, the second
As the piston 13 moves, the movable ring 3 and each movable vane 4 are moved to an intermediate state, and the opening area of the turbine nozzle of the turbine 1 is narrowed to an intermediate state between the fully open state and the throttle state. It is designed to be held in an apertured state.

On the other hand, 30 is a rotation speed detector that detects the rotation speed of the engine body a, and 31 is a boost pressure detector that detects the boost pressure Pb of supercharging air supplied into the engine body a from the compressor e of the exhaust turbo supercharger b. It is a detector. Output signals from the rotation speed detector 30 and boost pressure detector 31 are input to the controller 32 together with output signals from various detectors such as a load detector. This controller 32 controls the operating mechanism 7 according to the engine speed N and boost pressure Pb. That is, as shown in FIG. 6, the controller 32 has a first set value N ₁ that divides the engine speed N into a low speed rotation range and a medium speed rotation range, and a first set value N 1 that divides the engine speed N into a medium speed rotation range and a high speed rotation range. Second set value N ₂
The upper limit value Pb ₀ of the boost pressure Pb of the supercharging air discharged from the compressor e is set, and the engine speed N is maintained in the low speed rotation range as shown by the dashed line in Fig. 6. When the boost pressure Pb is maintained below the upper limit value Pb ₀ , the first and second electromagnetic switching valves 9 and 10 are switched between the first and second air supply pipes 24 and 25 and the third , the fourth air supply pipes 27 and 29 are switched to a state in which they are in communication with each other, and the second piston 13 is moved to the second displacement position shown in FIG. The engine speed N is maintained in the medium speed range and the boost pressure Pb is maintained at the upper limit.
If Pb is maintained below ₀ , the first
Switching the electromagnetic switching valve 9 to a state where the first air pipe 24 and the third air pipe 27 are in communication with each other,
The second electromagnetic switching valve 10 is switched to a state where the second air supply pipe 25 and the exhaust pipe 28 are communicated with each other, and each movable vane 4 is held in an intermediate throttle state. Further, when the engine speed N is maintained in a high speed range and the boost pressure Pb is maintained below the upper limit value Pb ₀ , the first and second electromagnetic switching valves 9 and 10 are 1. Each second air pipe 2
4, 25 and the respective exhaust pipes 26, 28 are switched to communicate with each other, and the second piston 13 is switched to the third
Move each movable vane 4 to the reference position shown in the figure.
It is designed to maintain the... in a fully open state. Furthermore, when the boost pressure Pb reaches the upper limit value Pb ₀ when the engine speed N is in the low-speed rotation range or the medium-speed rotation range, the first and second electromagnetic switching valves 9 .

Therefore, in the case of the above configuration, the boost pressure detector 3 detects the boost pressure Pb of the supercharging air discharged from the compressor e of the exhaust turbo supercharger b.
1 is provided, and the output signal from this boost pressure detector 31 is inputted to the controller 32 together with the output signal from the rotation speed detector 30, and this controller 3
2 by engine speed N and boost pressure
Since the opening degree of the variable nozzle vane 2 is switched and controlled based on Pb, even when the outside temperature is low and the boost pressure Pb tends to increase, such as in winter, the engine speed N is low or medium. Boost pressure Pb is maintained in each rotation range of
When reaches the upper limit value _Pb0 , the opening degree of the variable nozzle vane 2 is sequentially switched from the throttled state to the intermediate throttled state or from the intermediate throttled state to the fully open state, as shown by the solid line in FIG. Therefore, there is no risk that the boost pressure Pb will become excessive as in the conventional case, so that it is possible to prevent the cylinder internal pressure from becoming excessive, and it is possible to reliably prevent damage to the engine body a. Also, when the outside temperature is high, such as in the summer, the boost pressure
If Pb is difficult to rise, the opening degree of the variable nozzle vane 2 is changed when the engine speed N reaches the first and second set values N ₁ and N ₂ as shown by the dashed line in Fig. 6. Since the throttle valve is sequentially switched from a throttled state to an intermediate throttled state or from an intermediate throttled state to a fully open state, deterioration of the fuel consumption rate can be prevented.

It should be noted that this invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of this invention.

As explained above, according to this invention, a boost pressure detector is provided to detect the boost pressure of supercharging air supplied into the engine body from the compressor of the exhaust turbo supercharger, and the output from this boost pressure detector is The signal is input to the controller along with the output signal from the engine speed detector, and this controller controls the opening degree of the variable nozzle vane according to changes in engine speed and boost pressure, and controls either the engine speed or boost pressure. Since the opening degree of the variable nozzle vane is switched when one side reaches the set value, damage to the engine body can be reliably prevented even if the boost pressure changes due to the influence of outside temperature. can be used to improve safety.

[Brief explanation of the drawing]

Figure 1 is a relationship diagram showing the relationship between engine speed and boost pressure of a conventional turbocharged engine;
6 to 6 show an embodiment of this invention, FIG. 2 is a schematic diagram of the entire configuration, FIG. 3 is a schematic diagram of the entire configuration showing the operating mechanism of the variable nozzle vane,
4 and 5 are longitudinal cross-sectional views for explaining the operation of the operating mechanism, and FIG. 6 is a relationship diagram showing the relationship between engine speed and boost pressure. a...Engine body, b...Exhaust turbo supercharger, 1...Turbine, 2...Variable nozzle vane,
7... Operating mechanism, 30... Rotation speed detector, 31...
...boost pressure detector, 32...controller.

Claims (1)

[Scope of utility model registration request] An engine body including an exhaust turbo supercharger, a rotation speed detector for detecting the engine speed of the engine body, and a boost of supercharging air supplied into the engine main body from a compressor of the exhaust turbo supercharger. a boost pressure detector for detecting the pressure; a variable nozzle vane provided in the turbine nozzle of the turbine of the exhaust turbo supercharger for varying the opening degree of the turbine nozzle; an operating mechanism for opening and closing the variable nozzle vane; The operation of the operating mechanism is controlled according to changes in engine speed and boost pressure by inputting output signals from a speed detector and a boost pressure detector, and either the engine speed or boost pressure reaches a set value. A turbocharged engine comprising: a controller that switches the opening degree of the variable nozzle vane when the variable nozzle vane is opened.