JPS61207826A - Engine equipped with exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To improve the output in high-speed region without incurring the reduction of the output in low speed region by installing the second bypass passage separately from a bypass passage into an exhaust passage and reducing the dimension of a waiste gate valve. CONSTITUTION:The first valve 9a opens at the number N1 of engine revolution, and the opening degree gradually increases with the increase of the number of engine revolution, and the valve 9a is perfectly opened at the number N2 of engine revolution. The second valve 9b is switched from the perfect opening to the perfect closing when the number of revolution of the engine 9b reaches N2. A waiste gate valve 5 gradually increases its opening degree with the increase of the number of engine revolution after the number N2 of engine revolution is reached.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an exhaust turbo supercharger that is driven by exhaust gas for supercharging, and a bypass that bypasses the turbine of the exhaust turbo supercharger in the exhaust passage. The present invention relates to an engine with an exhaust turbo supercharger, which is provided with a wastegate valve that connects the bypass passage and opens and closes the bypass passage according to boost pressure.

(Prior Art) In a conventional engine with an exhaust turbo supercharger of this kind, the supercharging pressure was controlled only by opening and closing the waste gate valve (for example,
Utility Model Application Publication No. 58-20335).

However, in the conventional exhaust turbocharged engine, when the supercharging pressure reaches the set value and the wastegate valve opens and exhaust gas escapes from the bypass path, the wastegate valve acts as a throttle resistance for the exhaust gas. act. Therefore, as the exhaust volume increases in the high-speed range, the exhaust pressure acting on the engine increases, and as shown in Figure 6, the exhaust pressure (PTO) becomes higher than the boost pressure (Pg). This resulted in an increase in pumping loss, an increase in the amount of residual gas, and a significant drop in output at high speeds.

However, if the increase in exhaust pressure in the high speed range is suppressed by increasing the size of the wastegate valve to prevent a drop in output, the control of boost pressure in the low speed range by the wastegate valve must be accurate and accurate. It becomes difficult to do so, and the output at low speeds decreases.

(Problems to be Solved by the Invention) The present invention was developed in view of the above circumstances, and its purpose is to increase the exhaust pressure in the high speed range without causing a decrease in output in the low speed range. The purpose of this is to improve output in the high-speed range by suppressing the

(Means for Solving the Problems) A characteristic configuration of the exhaust turbo supercharged engine according to the present invention taken to achieve the above object is that the exhaust passage has a second bypass passage that bypasses the turbine and the bypass passage. The second bypass passage is connected to the second bypass passage and is provided with a valve mechanism for controlling the amount of exhaust gas discharged from the second bypass passage, and the effects thereof are as follows.

(Function) By controlling the valve mechanism and opening the second bypass path, exhaust gas can be released not only from the bypass path but also from the second bypass path, which will affect the characteristics of the supercharger and engine body. and controlling the valve mechanism appropriately based on the second
By appropriately setting the amount of exhaust gas released from the bypass path, the wastegate valve can be made smaller, and the boost pressure can be controlled accurately in the low speed range by this wastegate valve. However, in the high speed range, the exhaust gas can be released from the second bypass path to reduce the exhaust resistance and suppress or prevent an increase in the exhaust pressure.

(Effects of the Invention) Therefore, according to the present invention, the output in the high speed range can be improved without causing a decrease in output in the eccentric speed range, and as a whole, the exhaust gas can exhibit good output characteristics over the entire range. Now we can offer turbocharged engines.

(Example) Embodiments of the present invention will be described below based on the drawings.

[First Embodiment] In FIG. 1, (1) is an intake passage, (2) is an exhaust passage, and (3) is a turbine driven by exhaust gas for supercharging, that is, a turbine ( 3a) and a compressor (3b) directly connected to the compressor (3b) for pressurizing intake air;
3a), and (5) is a bypass passage that connects to the exhaust passage (2) while bypassing the This is a wastegate valve that opens and closes the bypass passage (4) in response to a supply pressure control signal to control the amount of exhaust gas supplied to the turbine (3a). Further, (7) is the turbine (3).
a) and the bypass passage (4) are both connected to the exhaust passage (2) in a detour manner, and the exhaust gas of the third cylinder (8) among the four cylinders (8) is routed to the turbine (3a) and the bypass passage (4). This is a second bypass path that allows exhaust to be discharged without passing through the bypass path (4), and (9) is a second bypass path that allows exhaust from the second bypass path (7) to be discharged by the boost pressure control signal from the controller (6). It is a valve mechanism that controls the amount of discharge. (10) is an air cleaner, (11) is an air flow sensor, (12) is a throttle valve linked to an accelerator pedal, and (13) is a silencer.

The amount of exhaust gas (Q) required by the exhaust turbo supercharger (3) in order to control the supercharging pressure (P,) to the set supercharging pressure (p,.) is shown by the solid line in FIG. As shown in (a), it changes depending on the engine speed (N). In other words, until the engine speed (N) rises to the intercept point (N1) that makes the boost pressure (Pa) reach the set boost pressure (pm), there is no way to increase the boost pressure (pH) faster. , exhaust gas for four cylinders is required, but as the engine speed (N) increases thereafter, exhaust gas for three cylinders or two cylinders becomes sufficient. In FIG. 2, (N, ) and (N,
) are the engine rotational speeds at which the turbine (3a) can be driven so as to obtain the set supercharging pressure (pso) with exhaust gas from three cylinders and two cylinders, respectively.

The valve mechanism (9) includes a first valve (9a) that opens and closes the second bypass passage (7), and a valve mechanism that prevents exhaust gas from the third cylinder (8) from going to the turbine (3a) and the bypass passage (4). A second valve (9b) capable of closing the exhaust passage (2) is provided. This valve (9a).

(9b) is to suppress the increase in exhaust pressure as much as possible, and is controlled to be fully open or fully closed by an external signal.

As shown in FIG. 3 (A), (C), and (D), the first valve (9a)
N1) The opening degree is gradually increased as the engine speed increases thereafter, and when the engine speed (N) reaches the above-mentioned point (N1), the second
The valve (9b) is controlled to switch from fully open to fully open when the engine speed (N) reaches the aforementioned point (N,), and the wastegate valve (5) is controlled to switch from fully open to fully open when the engine speed (N) reaches the aforementioned point (N,). , ) The opening degree is controlled to gradually increase as the engine speed (N) increases thereafter.

Therefore, when the engine speed (N) is between the intercept point (N1) and the point (N, ), the supercharging pressure (Pl) can be adjusted to exceed the set value by adjusting the opening degree of the first valve (9a). The supply pressure (pmo) is maintained at the engine speed (N
) is above the point (N, ), the set boost pressure (P
IIO). In a high-speed region where the engine speed (N) is above the point (N, ), the first valve (9a) is fully opened and the second valve (9b) is fully opened.
is fully closed, and the exhaust from the third cylinder (8) flows through the second bypass path (
7), and only the exhaust gas for three cylinders is supplied to the turbine (3a). As a result, the third cylinder (8)
Of course, the exhaust pressure caused by the drive of the turbine (3a) does not act, and the exhaust gas supplied to the turbine (3a) side is for three cylinders, and the boost pressure (pm) is set to the boost pressure (pm).

) while driving the turbine (3a) to maintain the cylinder (8), the exhaust pressure acting on the remaining cylinder (8) is reduced.
Overall, pumping loss and residual gas can be reduced.

[Second Embodiment] As shown in FIG. 4, the valve mechanism (9) includes a second embodiment.
A first valve (9a) that opens and closes the bypass passage (7), and a first valve that can close the exhaust passage (2) so that the exhaust gas from the fourth cylinder (8) does not go to the turbine (3a) and the bypass passage (4). 2 valves (9b') and a third valve (9c) capable of closing the exhaust passage (2) so that the exhaust gas of the third cylinder (8) does not go to the turbine (3a) and the bypass passage (4). . When using this valve mechanism (9), each valve (9a
).

By controlling the opening and closing of (9b') and (9c) as appropriate, the first state in which the amount of exhaust gas supplied to the turbine (3a) side is equal to that of four cylinders, and the second state in which the exhaust gas from the fourth cylinder (8) is A second state in which the amount of exhaust gas supplied to the turbine (3a) side is equal to that of three cylinders by discharging through the bypass passage (7), and a second state in which the exhaust gas from the third and fourth cylinders (8) is discharged through the second bypass passage (7). It is possible to switch to the third state in which the amount of exhaust gas supplied to the turbine (3a) is equal to that of two cylinders by discharging the exhaust gas through the engine, and when the engine speed (N) reaches the above-mentioned point (N, When it switches to the second state, the engine rotation (N) reaches the above-mentioned point (
It is common to switch to the third state when N, ) is reached. Then, when switching to the third state, the exhaust pressure (P) of the first and second cylinders (8) is lower than the supercharging pressure (P), as in the conventional case, as shown in Fig. 6. However, the exhaust pressure (Pt+) of the third and fourth cylinders (8) becomes lower than the supercharging pressure (pm) as shown in FIG. 5, and the pumping loss becomes smaller as a whole.

In addition, in the example, the first valve (9a) and the second valve (
9b) shall be controlled to open and close by an external signal, but
This may be an existing wastegate valve type whose opening and closing are controlled by boost pressure. Further, in the embodiment, an example of application to a four-cylinder engine is shown, but the present invention can also be applied to engines with various numbers of cylinders, such as a single cylinder and six cylinders, and can also be used to distinguish between gasoline engines and diesel engines. It can be applied to both piston and rotary engines.

[Brief explanation of the drawing]

Figures 1 to 3 show embodiments of the present invention, with Figure 1 being a schematic diagram, Figure 2 being a graph showing the relationship between engine speed and exhaust volume, and Figure 3 (A) being a graph showing the relationship between engine speed and exhaust volume. Graphs showing changes in supply pressure, Figures 3 (II) and (C). (D) is a graph showing the opening/closing operation of each valve. FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention, and FIG. 5 is a p-type diagram of the third and fourth cylinders in the second embodiment.
FIG. 6 is a v diagram, and FIG. 6 shows the first and second
It is a P-v diagram of a cylinder and a conventional engine. (3)... Exhaust turbo supercharger, (2)...
...Exhaust passage, (3a)...Turbine, (4)
...Bypass path, (5) ... Waste gate valve, (7) ... Second bypass path, (
9)...Valve mechanism, (9a)...First pulse 7', (9b)...Second valve.

Claims (2)

[Claims] (1) An exhaust turbo supercharger that is driven by exhaust gas for supercharging is provided, a bypass passage that bypasses the turbine of the exhaust turbo supercharger is connected to the exhaust passage, and this bypass passage is set to supercharging pressure. In an engine with an exhaust turbo supercharger that is equipped with a wastegate valve that opens and closes accordingly,
An engine with an exhaust turbo supercharger, wherein a second bypass passage that detours around the turbine and the bypass passage is connected to the exhaust passage, and a valve mechanism is provided for controlling the amount of exhaust gas discharged from the second bypass passage. (2) The number of cylinders is complicated, and the valve mechanism is capable of closing the first valve that opens and closes the second bypass passage and the exhaust passage so that the exhaust gas of a specific cylinder does not go to the turbine and the bypass passage. The engine with an exhaust turbo supercharger according to claim 1, further comprising a second valve.