JPH0117616Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a variable displacement turbocharger.

The operating characteristics of a conventional turbocharger are as shown in FIG. 1, and it operates at the midpoint in FIG. 1 in a high engine speed range. In this respect, as can be seen from the figure, the turbine expansion ratio π _T is large. The theoretical gas velocity C ₀ can be calculated by the following equation.

where g: gravitational acceleration, K _T : gas specific heat ratio R: gas constant, T _iT : turbine inlet temperature, π _T : expansion ratio. That is, C ₀ becomes large, so the turbine rotational speed N _T becomes large, and therefore the rotational speed N _c of the compressor coaxial with the turbine becomes large.
Boost pressure increases. When the engine is in a low rotational speed range, the mass flow rate per unit time is small, so the operating point is a point in FIG. Comparing this with the point of high engine speed, the expansion ratio π _T is small, and therefore, based on the same theory as above, the theoretical gas speed is small, and the boost pressure is low. This is shown on the characteristic line of the compressor as shown in Fig. 2. Since the boost pressure is low, the amount of intake air is small, and the fuel injection amount is controlled by the exhaust gas concentration limit, which has the disadvantage of reducing torque.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and increase the turbine rotor rotational speed by increasing the exhaust gas velocity in the low engine rotational speed range.
To provide a variable displacement turbocharger that increases boost pressure, increases fuel injection amount, and increases engine torque at low engine speeds.

The variable displacement turbocharger of the present invention divides the exhaust passage of the turbine housing into a plurality of parts using a partition wall, and the partition plates provided at the exhaust inlet of the divided turbine housing are sequentially closed off in the middle, low speed and high load range of the engine. It is designed to achieve the following.

The following is an example of the present invention shown in Figures 3 to 8.
This will be explained in detail with reference to the drawings.

In Fig. 3a, 1 is a turbine rotor, 2 is a turbine housing, 3 and 3' are partition walls in the turbine housing, 4 is a partition plate, 5 is an air cylinder that moves the partition plate 4, 6 is an exhaust manifold, 7 is a load sensor,
8 is an engine rotation speed sensor, and 9 is a controller which receives signals from the load sensor 7 and the engine rotation sensor 8 and controls the solenoid valve. 10,11
1 is a solenoid valve operated by a signal from the controller 9, 12 is an air tank, 13, 1
4 and 15 indicate the positions of the partition plates 4. 16 is a piston, 16' is a stopper, 17 is a piston, and 18 is a spring. Note that FIG. 3b is a sectional view taken along line E-E in FIG. 3a.

Next, the operation of the above embodiment will be explained.

Position 13,1 of the partition plate 4 as shown in Figure 3a
4 and 15, the nozzle blowout area of the exhaust passage is divided into three in the circumferential direction, so there are also three turbine flow characteristics, A, B, and C in FIG.

As shown in the shaded areas in Figures 6a and 6c, the engine speed is greater than N ₂ and less than the maximum engine load L _nax , and the engine speed is less than or equal to N ₂ and the maximum load L In a predetermined engine load A' region below engine load L ₀ , which is a value smaller than _nax , the controller 9 operates the solenoid valve 1 as shown in FIG.
0 and 11 are both turned off, and the air cylinder 5 is opened to the atmosphere.

Therefore, the piston 17 is pushed to the right by the biasing force of the spring, the partition plate 4 is at the position 13, and the divided passage of the turbine housing is fully opened. At this time, the characteristics of the turbine are shown by line A in FIG. 4, and the operating point shown by a in FIG. 6 is shown by a mark on line A.
The operating point of the blower at this time is shown in FIG.

It should be noted that the specific values for the engine speeds N ₁ , N ₂ and engine load L ₀ shown in Fig. 6 a, b, and c differ depending on the total displacement of the applied engine. Although they cannot be uniformly specified, an example of N ₁ , N ₂ and L ₀ used in FIGS. 6a, b, and c above is as follows.

N ₁ = (0.45 to 0.6) N _nax N ₁ = (0.75 to 0.8) N _nax L ₀ = (0.5 to 0.8) L _nax where N _nax is the maximum engine speed,
L _nax represents the maximum engine load, respectively.

In this way, when the sunken passage is fully opened in the A' region where the load L is less than ₀ , which is the partial load region,
Since engine exhaust resistance is reduced, pumping loss during engine intake and exhaust can be reduced.
Furthermore, it has the effect of reducing fuel consumption.

In region B' where the engine speed is greater than N ₁ and less than N ₂ and the engine load is greater than L ₀ , the controller 9 turns on only the solenoid valve 11 as shown in FIG. 6b, so the high pressure air in the air tank 12 is It enters the right side of the air cylinder 5, that is, the side without the piston rod, and pushes the piston 16 to the left, so that the piston 16 hits the stopper 16'. The partition plate is at position 14 and closes off one of the divided passages.
As the exhaust passage becomes narrower, the flow rate changes, and the line representing the turbine characteristics shifts to line B in Figure 4, and the operating point shown in a in Figure 6 is on line B. At this time, the operating point of the blower is This becomes the point in Figure 5.

Next, in region C' where the engine speed is less than N ₁ and the engine load is greater than load L ₀ , the controller 9 uses the signals from the load sensor 10 and rotation sensor 11 to control both solenoid valves 1 as shown in FIG.
Set both 0 and 11 to ON or only 10 to ON.
The air pressure enters the left side of the stopper 16' of the air cylinder 5 and presses the piston 17 further to the left, the partition plate 4 takes the position 15, and one more divided passage of the turbine housing 2 is closed off. Since the passage changes, the flow path changes, and the line indicating the turbine characteristics changes to the fourth line.
This becomes line C in the figure, and the operating point shown by a in FIG. 6 is a point on line C. Therefore, the expansion ratio π _T becomes even larger than following the line B in FIG. 4, the operating point of the blower is shown by the point in FIG. 5, and although the flow rate decreases, the pressure ratio π _c becomes relatively large.

As it operates as described above, the boost pressure will be as shown in Figure 7 with respect to the engine rotational speed, and the boost pressure will be high even when the engine is at low speed, and the amount of intake air at low speed will increase, so the amount of fuel injection will be reduced. Therefore, the low-speed torque of the engine can be increased. The characteristics of the conventional structure are as follows:
As shown by the broken line in the figure, it is clear that the present invention shown by the solid line improves the boost pressure. Note that A″, B″, and C″ in FIG. 7 are curves corresponding to the full load in each partition plate situation in FIG. 6.

Next, a second embodiment showing another structure of the partition plate 4 is shown in FIG. Note that 3 and 3' are partition walls inside the turbine housing.

FIG. 9 shows that the annular flow passages of the turbine rotor 20 and the turbine housing 21 are provided with nozzle rings 22 and nozzle vanes 23 of equal or unequal pitch in order to increase the turbine efficiency. The exhaust gas angle and even the desired throttling are obtained.

As mentioned above, the variable displacement turbocharger according to the present invention has a turbine housing in which the nozzle blowout area of the exhaust flow is divided into three passages in the circumferential direction by a partition wall, and a partition plate is provided between the housing inlet and the exhaust manifold. The above-mentioned divided passages are closed sequentially depending on the engine rotation speed and engine load, so even when the engine speed is low, the exhaust gas velocity is increased, the turbine rotation speed is increased, the boost pressure is increased, and the fuel injection amount is increased. However, the engine torque can be increased.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the turbine characteristics of a conventional device.
FIG. 2 is a diagram showing the blower characteristics of the device, FIG. 3 a is an explanatory diagram showing the structure of the first embodiment of the present invention, FIG. Fig. 4 is a turbine characteristic diagram of the same embodiment, Fig. 5 is a diagram showing the blower characteristics of the same embodiment, Fig. 6 a and c are graphs showing the control region of the same embodiment, and Fig. 6 b is a graph showing the control region of the same embodiment. Figure 7 is a diagram showing the operation of the solenoid valve in the same example, Figure 7 is a relationship diagram showing the engine speed, boost pressure, and torque in the same example, and Figure 8 is a second diagram showing another structural example of the partition plate. A sectional view of the embodiment, FIG. 9 is a structural diagram in the case where a nozzle vane and a nozzle ring are provided in an annular flow path between a turbine rotor and a turbine housing. 2... Turbine housing, 3, 3'... Partition wall,
4... Partition plate, 6... Manifold.

Claims (1)

[Scope of utility model registration request] a turbine housing in which an exhaust passage has a nozzle blowing area divided into three in the circumferential direction by a partition; a partition plate provided between an inlet of the turbine housing and an exhaust manifold to sequentially close off the divided exhaust passages; and control means for operating the partition plate based on output signals from the load sensor and the engine rotational speed sensor,
N ₁ = (0.45 to 0.6) N _nax , N ₂ = (0.75 to 0.8) N _nax ,
When N _nax is the maximum engine speed, the engine speed is greater than N ₂ and the maximum engine load is
The operating situation in region A' and the control means at an engine load smaller than L _nax and an engine speed of _N2 or less, and a predetermined engine load _L0 or less between no-load and maximum engine load _Nnax . When it is determined that, the partition plate fully opens the divided passage, and the operating conditions in region B' where the engine speed is greater than N ₁ and less than N ₂ and the engine load is greater than the engine load L ₀ and the above control are determined. When the means determines that one of the divided passages is closed, the operating condition in a region C' where the engine speed is N1 _or less and the engine load is greater than the predetermined engine load _L0 and the control means is A variable displacement turbocharger characterized in that, when determined, two of the divided passages are closed off by the partition plate.