JP2007211606A - Engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasoline engine with a supercharger capable of surely increasing a low-speed torque. <P>SOLUTION: This engine with the supercharger comprises an engine body 2 having a first cylinder group 4b, 4c and a second cylinder group 4a, 4d the firing orders of which are discontinuous, a first exhaust passage 6 branched and connected to the cylinders of the first cylinder group, collected on the downstream side, and having a first volume, a second exhaust passage 8 branched and connected to the cylinders of the second cylinder group, collected on the downstream side, and having a second volume larger than the first volume, and the variable displacement supercharger 14. The variable displacement supercharger comprises an inner peripheral scroll chamber 20 and an outer peripheral scroll chamber 22 formed around a turbine and a control valve 30 controlling the flow of exhaust gases from the inner peripheral scroll chamber to the outer peripheral scroll chamber. The first exhaust passage is connected to the inner peripheral scroll chamber, and the second exhaust passage is connected to the outer peripheral scroll chamber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine with a supercharger, and more particularly to an engine with a variable displacement supercharger.

An engine equipped with a supercharger (so-called turbocharger) that uses exhaust pressure can obtain a high output, but has a characteristic that the low-speed torque is relatively small because the supercharging efficiency decreases at low engine speed with low exhaust energy. Have
In such a supercharger, a variable capacity supercharger in which a scroll chamber is defined in the radial direction of the turbine and an inner scroll chamber and an outer scroll chamber are provided is known (for example, Patent Document 1). An example of such a conventional variable capacity supercharger is shown in FIG. As shown in FIG. 7, in a conventional variable displacement supercharger, for example, in the case of a four-cylinder engine, the exhaust passages of these four cylinders are gathered into one exhaust passage 200 and flowed into the supercharger 202. The turbine 224 is rotated. At the time of low rotation, the control valve 204 is closed, and the exhaust pressure of all four cylinders is caused to flow into the inner scroll chamber 206 to increase the supercharging pressure. On the other hand, at the time of high rotation, the control valve 204 is opened, and the exhaust pressure flows into both the inner scroll chamber 206 and the outer scroll chamber 208 to adjust the supercharging pressure. In this way, the supercharging capability is increased in a wide rotation range from low speed to high speed.

  Further, a twin scroll supercharger is known in which a scroll is partitioned in the turbine axis direction and two scroll chambers having substantially the same capacity and flow velocity are provided (Patent Document 2). In the twin scroll turbocharger described in Patent Document 2, a group in which the ignition order is not continuous is provided in the exhaust passage of each cylinder (for example, the ignition order is 1st cylinder → 3rd cylinder → 4th cylinder → 2nd cylinder). If so, it is divided into a group of the second cylinder and the third cylinder and a group of the first cylinder and the fourth cylinder). The exhaust passages of these groups are connected to the respective scroll chambers to prevent exhaust interference.

JP 2001-263078 A Japanese Patent Laid-Open No. 2004-1224749

  Here, in recent years, there has been a strong demand for improvement in fuel consumption and response to environmental problems. In order to improve fuel efficiency and environmental issues, it is advantageous that the engine displacement be as small as possible. However, if the engine displacement is lowered, the engine output is lowered, and the running performance is sacrificed. As one of the solutions to such a problem, it is conceivable to improve the engine output by a supercharger and, as a result, achieve both fuel consumption and driving performance. For practical use of such an engine, it is required to improve the low-speed torque, particularly in the extremely low speed region, as compared with the above-described turbocharger according to the prior art.

The inventors of the present application have focused on the fact that the exhaust pressure is higher as the volume of the exhaust passage is smaller, and have attempted to solve the above-described problems of the prior art.
An object of this invention is to provide the gasoline engine with a supercharger which can improve a low speed torque reliably.

In order to achieve the above object, an engine with a supercharger according to the present invention includes a plurality of cylinders that are ignited in a predetermined ignition order, and includes a first cylinder group and a second cylinder group in which the ignition order is discontinuous. The engine main body is branched and connected to the cylinders of the first cylinder group and is gathered on the downstream side and has a first volume. The first exhaust passage is branched and connected to the cylinders of the second cylinder group and is downstream. A second exhaust passage having a second volume larger than the first volume, and a variable displacement type that is provided downstream of the first and second exhaust passages and operates by exhaust energy flowing through these exhaust passages The variable displacement supercharger includes a turbine housing, a turbine housed in the turbine housing and rotated by exhaust energy, an inner peripheral scroll chamber formed around the turbine, and a turbine. An outer peripheral scroll chamber, and a control valve for controlling the flow of exhaust gas from the inner peripheral scroll chamber to the outer peripheral scroll chamber. The first exhaust passage is connected to the inner peripheral scroll chamber, and the second exhaust passage is connected to the outer peripheral scroll chamber. It is characterized by being connected.
In the present invention configured as described above, since the first or second exhaust passage is connected to each of the cylinder groups in which the firing order is discontinuous, a reduction in exhaust energy due to exhaust interference is suppressed, Furthermore, since the first exhaust passage has a smaller exhaust volume than the second exhaust passage, the exhaust pressure is less reduced. And since this 1st exhaust passage is connected to the inner peripheral scroll chamber with high supercharging efficiency, the supercharging capability at the time of low speed can be improved. As a result, the low speed torque can be improved with certainty.

In the present invention, preferably, the engine is an in-line four-cylinder engine, the first cylinder group is a group of a second cylinder and a third cylinder, and the second cylinder group is a first cylinder and a fourth cylinder. It is a group of.
In the present invention configured as described above, since the first exhaust passage is connected to the second and third cylinders which are adjacent cylinders, the volume of the first exhaust passage can be easily reduced. Therefore, it is possible to reliably suppress the reduction of the exhaust pressure and improve the low-speed torque more reliably.

In the present invention, it is preferable that the turbine housing includes a first opening to which the downstream end of the first exhaust passage is connected, a second opening to which the downstream end of the second exhaust passage is connected, A partition wall that divides the peripheral scroll chamber and the outer scroll chamber, and the partition wall includes a third opening on the upstream side thereof that is opened and closed by a control valve and allows exhaust to flow from the inner scroll chamber to the outer scroll chamber. The second opening is formed at the outer edge of the turbine housing so as to face the third opening.
In the present invention configured as described above, since the second opening is formed at the outer edge of the turbine housing so as to face the third opening, the second opening is formed in the control valve in the turbine housing. Can be used also as a connection port for attaching the second exhaust passage.

In the present invention, it is preferable that the exhaust passage further includes an exhaust bypass passage that bypasses the turbine, and a supercharging pressure control valve that opens the bypass passage when the supercharging pressure reaches a predetermined value or more. The first exhaust passage is connected to the inner scroll chamber or the first exhaust passage so as to bypass the exhaust.
In the present invention configured as described above, since the exhaust gas in the first exhaust passage having a high exhaust pressure is bypassed, the ratio of the amount of exhaust gas flowing in from the second exhaust passage having a low exhaust pressure becomes larger. Further, the exhaust gas flowing from the second exhaust passage flows into the outer peripheral scroll chamber having a supercharging efficiency lower than that of the inner peripheral scroll chamber. Therefore, the exhaust pressure can be effectively reduced.

  According to the gasoline engine with a supercharger of the present invention, the low-speed torque can be reliably improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, the main configuration of an engine with a supercharger according to an embodiment of the present invention will be described with reference to FIGS. 1 is a top view showing a schematic configuration of an engine with a supercharger according to an embodiment of the present invention, and FIG. 2 shows a schematic configuration of the engine with a supercharger as seen from the direction of the arrow indicated by II in FIG. FIG.
As shown in FIG. 1, the engine 1 is an in-line four-cylinder gasoline engine in which first to fourth cylinders 4 a to 4 d are formed in an engine block 2. In the engine 1, ignition is performed in the order of the first cylinder 4a, the third cylinder 4c, the fourth cylinder 4d, and the second cylinder 4b. Therefore, the exhaust process is not continued in the second cylinder 4b and the third cylinder 4c (first cylinder group), and in the first cylinder 4a and the fourth cylinder 4d (second cylinder group). An intake passage (not shown) for introducing intake air to the cylinders 4a to 4d is connected to the cylinders 4a to 4d via an intake port (not shown).

  Next, as shown in FIGS. 1 and 2, in the cylinders 4a to 4d, the first exhaust passage 6 and the second exhaust passage 8 for leading the exhaust from the cylinders 4a to 4d are provided with exhaust ports (not shown). Connected through. The exhaust passages 6 and 8 are a group of a plurality of exhaust passages, and the first exhaust passage 6 includes branch exhaust passages 10b and 10c for the second and third cylinders 4b and 4c, and branches of these. The exhaust passages 10b and 10c are combined to form a collective exhaust passage 12a. The second exhaust passage 8 includes branch exhaust passages 10a and 10d for the first and fourth cylinders 4a and 4d, and a collective exhaust passage 12b formed by collecting these branch exhaust passages 10a and 10d. Yes.

In this way, the exhaust passages 10b, 10c, 12a for deriving the exhaust of the second cylinder 4b and the third cylinder 4c are grouped to form a first exhaust passage group (first exhaust passage 6), and the first The exhaust passages 10a, 10d, and 12b for deriving exhaust from the cylinder 4a and the fourth cylinder 4d are grouped to form a second exhaust passage group (second exhaust passage 8).
Here, in this embodiment, as shown in FIG. 1, the first exhaust passage 6 is an exhaust passage for the adjacent cylinders 4b and 4c, so that it is more than the exhaust passages 10b and 10c for the separated cylinders 4a and 4d. The length of the tube is shortened. Therefore, in the present embodiment, the exhaust volume of the first exhaust passage 6 (volume of the exhaust passages 10b, 10c, 12a) is smaller than the exhaust volume of the second exhaust passage 8 (volume of the exhaust passages 10a, 10d, 12b). It has become.

The downstream ends of the collective exhaust passages 12 a and 12 b are connected to the turbine section 16 of the variable capacity turbocharger 14. Next, the structure of the turbine section 16 of the variable capacity turbocharger 14 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the turbine section of the variable capacity turbocharger as seen along line III-III in FIG.
A turbine 24 is provided in the turbine housing 18 of the turbine unit 16, and an inner peripheral scroll chamber 20 and an outer peripheral scroll chamber 22 are formed around the turbine 24. The inner peripheral scroll chamber 20 and the outer peripheral scroll chamber 22 are partitioned by a partition wall 26. A common exhaust passage 25 (see FIG. 1) through which the exhaust gas that has passed through the turbine 24 flows is provided on the downstream side of the turbine unit 16.
The turbine 24 is rotated by the exhaust energy flowing into the turbine housing 18, and this rotational force rotates a compressor (not shown) provided in the intake passage (not shown). The intake air inside is compressed.

  A first opening 27 is formed in the turbine housing 18 on the upstream side of the inner scroll chamber 20, and a second opening 28 is formed on the upstream side of the outer scroll chamber 22. The first opening 27 is connected to the collective exhaust passage 12 a of the first exhaust passage 6, and the second opening 28 is connected to the collective exhaust passage 12 b of the second exhaust passage 8. As described above, in the present embodiment, the exhaust from the second and third cylinders 4b and 4c flows into the inner scroll chamber 20, and the first and fourth cylinders 4a and 4d enter the outer scroll chamber 22. Exhaust gas flows in.

  In the partition wall 26, a communication opening 29 for allowing exhaust gas flowing in from the second and third cylinders 4 b and 4 c to flow into the outer scroll chamber 22 is formed in the upstream portion. The communication opening 29 is opened and closed by a control valve 30 that is operated by a control valve actuator 32 (see FIG. 1). The partition wall 26 is formed with a plurality of communication holes 34 for allowing the exhaust from the outer scroll chamber 22 to flow into the inner scroll chamber 20 at a portion downstream of the communication opening 29.

  Here, the second opening 28 described above is formed in the outer peripheral wall 36 of the turbine housing 18 so as to face the communication opening 29. In the present embodiment, the second opening portion 28 serves to introduce exhaust gas from the second exhaust passage 8 and also serves as a so-called service hole for mounting the control valve 30 in the turbine housing 18. In other words, after the control valve 30 is attached via the service hole 28, the collective exhaust passage 12b is connected to the second opening 28 to obtain the configuration shown in FIG.

In this embodiment, the control valve 30 is closed as shown by a solid line in FIG. Therefore, at the time of low rotation, all the exhaust from the second and third cylinders 4b, 4c flows into the inner scroll chamber 20, and all the exhaust from the first and fourth cylinders 4a, 4d all flows into the outer scroll chamber. 22 flows in.
On the other hand, at the time of high engine rotation, the control valve 30 is opened as shown by a broken line in FIG. Therefore, at the time of high rotation, a part of the exhaust from the second and third cylinders 4b and 4c flows into the outer scroll chamber 22, and the supercharging pressure is adjusted.

  Here, the exhaust gas flowing into the inner scroll chamber 20 hits the turbine 24 at an angle close to the tangential direction of the turbine 24 (circumferential direction with respect to the axis of the turbine 24), while the exhaust gas flowing into the outer scroll chamber 22 is After passing through the communication hole 34, the turbine 24 hits the turbine 24 at an angle inclined in the radial direction with respect to the tangential direction of the turbine 24. Therefore, in this embodiment, the supercharging efficiency by the exhaust gas flowing into the inner peripheral scroll chamber 20 becomes higher.

Next, the turbine section 16 is provided with a bypass passage that bypasses the turbine 24 and flows exhaust gas when the turbocharger is in a supercharged state. The configuration related to the exhaust bypass passage will be described with reference to FIGS. FIG. 4 is a cross-sectional view of a turbine portion for explaining an exhaust bypass passage and a waste gate valve, and FIG. 5 is a cross-sectional view of a W / G actuator for opening and closing the waste gate valve.
As shown in FIG. 4, a bypass passage 40 that bypasses the exhaust gas flowing into the inner scroll chamber 20 is formed in the turbine housing 18. The inlet opening 42 of the bypass passage 40 is formed in the upstream portion of the inner scroll chamber 20 (see FIG. 3), and the outlet opening 44 is formed in the common exhaust passage 25. The inlet opening of the bypass passage 40 may be formed in the collective exhaust passage 12 a of the first exhaust passage 6.

The inlet opening 42 is opened and closed by a waste gate valve 46. As shown in FIGS. 1 and 2, the waste gate valve 46 is connected to a W / G (waste gate valve) actuator 50 via a link mechanism 48. 1 and 2, the illustration of the bypass passage 40 is omitted.
As shown in FIG. 5, the W / G actuator 50 is provided with a compartment 51 and a spring 52. The compartment 51 is connected to an intake passage (not shown). In this W / G actuator 50, when the supercharging pressure in the intake passage exceeds a predetermined pressure value at which supercharging occurs, the supercharging pressure overcomes the force of the spring 51, and the link mechanism 48 in the direction indicated by the arrow in FIG. Is to be activated. By such an operation of the link mechanism 48, the waste gate valve 46 is opened as shown by a broken line in FIG.

Next, the effect of this embodiment is demonstrated.
In the present embodiment, the first exhaust passage 6 is an exhaust passage for the second cylinder 4b and the third cylinder 4c where the exhaust process is not continuous, and the second exhaust passage 8 is a first where the exhaust process is not continuous. Since the exhaust passages are for the first cylinder 4a and the fourth cylinder 4d, exhaust interference is less likely to occur. Accordingly, it is possible to suppress a decrease in exhaust energy due to exhaust interference, and as a result, it is possible to increase supercharging efficiency.

  Here, conventionally, as shown in FIG. 7, for example, in a four-cylinder engine, exhaust passages (not shown) of four cylinders are connected to a single collective exhaust passage 200, and this collective exhaust passage is connected to a variable displacement type excess passage. It was connected to the feeder 202. In such a format, since all the exhaust passages for the four cylinders are gathered, the volume of the exhaust passage becomes large, and the reduction amount of the exhaust pressure is large. On the other hand, in the present embodiment, since the exhaust passage is divided into two groups of the first exhaust passage 6 and the second exhaust passage 8, the respective volumes of the exhaust passages 6 and 8 are larger than the volume of the conventional exhaust passage. Becomes smaller. Therefore, the reduction amount of the exhaust pressure can be reduced.

Further, as described above, the exhaust volume of the first exhaust passage 6 (volume of the exhaust passages 10b, 10c, 12a) is smaller than the exhaust volume of the second exhaust passage 8 (volume of the exhaust passages 10a, 10d, 12b). It has become. Accordingly, the exhaust pressure is higher in the first exhaust passage 6 than in the second exhaust passage 8. That is, the supercharging capability is also increased. As described above, the first exhaust passage 6 is connected to the inner peripheral scroll chamber 20 in which the supercharging efficiency is increased by the exhaust gas flowing in the tangential direction of the turbine 24. Is closed. Therefore, at the time of low rotation, the supercharging efficiency can be reliably and greatly increased as compared with the conventional one, and as a result, the low speed torque is also improved.
On the other hand, as the engine speed increases, the exhaust pressure in the inner scroll chamber 20 also increases. However, as described above, the control valve 30 is opened during high rotation, and the exhaust gas flowing into the inner scroll chamber 20 is sent to the outer scroll chamber 22. The supercharging pressure can be adjusted by letting it escape.

  Next, in the present embodiment, the bypass passage 40 and the waste gate valve (supercharging pressure control valve) 46 for relief of exhaust gas to the common exhaust passage 25 are provided, so that the exhaust pressure is reduced during supercharging. I can do it. In particular, since the inlet opening 42 of the bypass passage 40 is formed in the upstream portion of the inner scroll chamber 20, the exhaust of the first exhaust passage 6 having a high exhaust pressure is relieved during supercharging, and the exhaust pressure is reduced. The ratio of the amount of exhaust gas flowing in from the second exhaust passage 8 having a lower value becomes larger. Therefore, the exhaust pressure can be effectively reduced. Here, the exhaust gas flowing in from the second exhaust passage 8 flows into the outer scroll chamber 22, and the supercharging efficiency by the exhaust gas flowing into the outer scroll chamber 22 is the excess efficiency due to the exhaust gas flowing into the inner scroll 20 as described above. Lower than feed efficiency. Therefore, the amount of supercharging that has become supercharging can be effectively reduced.

  Next, in the present embodiment, the collective exhaust passage 12 b of the second exhaust passage 6 is connected to the second opening 28. The second opening 28 also serves as a so-called service hole for mounting the control valve 30 in the turbine housing 18. As shown in FIG. 7, such a service hole 228 is conventionally covered with a lid member 210 after the control valve 204 is attached. In the present embodiment, by using such a service hole as an exhaust inflow port, the conventionally used variable capacity supercharger as shown in FIG. 7 can be used without changing the shape.

  The turbine unit 16 may be configured as a turbine unit 116 according to the modification shown in FIG. In this modification, the second opening 128 connecting the collective exhaust passage 112b of the second exhaust passage 8 is not the first opening connecting the collective exhaust passage 112a of the first exhaust passage 6 instead of the turbine housing outer peripheral wall 136. It is arranged side by side on the same side as 127. Other basic configurations are the same as those in the above-described embodiment, and are denoted by the same reference numerals. Even when the turbine section 116 according to this modification is used, the same operational effects as those described above can be obtained.

  Here, in general, in an in-line four-cylinder engine, considering the ignition sequence, the exhaust passage group in which exhaust interference hardly occurs is as described above (see FIG. 1). That is, the first exhaust passage (6) connected to the second and third cylinders (4b, 4c) and the second exhaust passage (8) connected to the first and fourth cylinders (4a, 4d). Grouped into In such a case, since the second and third cylinders are adjacent to each other and the first and fourth cylinders are separated from each other, a difference in volume tends to occur in each exhaust passage in terms of layout. In other words, the volume of the first exhaust passage (6) can be very small. Further, in an in-line four-cylinder engine, exhaust interference becomes very small due to grouping. Therefore, an in-line four-cylinder engine is considered to be an engine type particularly suitable for applying the present invention. On the other hand, in addition to the in-line four-cylinder type, taking into account the ignition order, exhaust pipe grouping and exhaust pipe routing that are less likely to cause exhaust interference, for example, other types of engines such as a V-type six-cylinder type It can also be applied to.

1 is a top view showing a schematic configuration of a supercharged engine according to an embodiment of the present invention. FIG. 2 is a side view showing a schematic configuration of the engine with a supercharger as seen from the direction of the arrow indicated by II in FIG. It is sectional drawing of the turbine part of the variable capacity | capacitance type turbocharger seen along the III-III line of FIG. It is sectional drawing of the turbine part for demonstrating the bypass passage and waste gate valve of exhaust. It is sectional drawing of the W / G actuator which opens and closes a waste gate valve. It is sectional drawing of the turbine part by the modification of a variable capacity type turbocharger. It is sectional drawing of the turbine part of the variable capacity type turbocharger by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 4a-4d 1st-4th cylinder 6 1st exhaust passage 8 2nd exhaust passage 10a-10d Branch exhaust passage 12a, 12b, 112a, 112b Collective exhaust passage 14 Variable capacity type turbocharger 16, 116 Turbine part 18 turbine housing 20 inner scroll chamber 22 outer scroll chamber 24 turbine 25 common exhaust passage 26 partition wall 27, 127 first opening 28, 128 second opening 29 communication opening 30 control valve 34 communication holes 36, 136 turbine housing Outer peripheral wall 40 Bypass passage 42 Inlet opening 46 Wastegate valve

Claims (4)

An engine body having a plurality of cylinders that are ignited in a predetermined ignition order, and having a first cylinder group and a second cylinder group in which the ignition order is discontinuous;
A first exhaust passage branched and connected to the cylinders of the first cylinder group and having a first volume gathered downstream;
A second exhaust passage that is branched and connected to the cylinders of the second cylinder group and is gathered downstream and has a second volume larger than the first volume;
A variable displacement supercharger that is provided downstream of the first and second exhaust passages and operates by exhaust energy flowing through the exhaust passages;
The variable capacity supercharger includes a turbine housing, a turbine housed in the turbine housing and rotated by exhaust energy, an inner scroll chamber and an outer scroll chamber formed around the turbine, and the inner scroll. A control valve for controlling the flow of exhaust gas from the chamber to the outer scroll chamber,
The supercharged engine, wherein the first exhaust passage is connected to the inner scroll chamber, and the second exhaust passage is connected to the outer scroll chamber. The engine is an inline 4-cylinder engine,
The supercharged engine according to claim 1, wherein the first cylinder group is a group of a second cylinder and a third cylinder, and the second cylinder group is a group of a first cylinder and a fourth cylinder. The turbine housing includes a first opening to which the downstream end of the first exhaust passage is connected, a second opening to which the downstream end of the second exhaust passage is connected, the inner peripheral scroll chamber, and the A partition wall that partitions the outer scroll chamber,
The partition wall includes, on the upstream side, a third opening that is opened and closed by the control valve and allows exhaust to flow from the inner scroll chamber to the outer scroll chamber.
2. The engine with a supercharger according to claim 1, wherein the second opening is formed at an outer edge of the turbine housing so as to face the third opening. 3. And an exhaust bypass passage that bypasses the turbine, and a supercharging pressure control valve that opens the bypass passage when the supercharging pressure becomes a predetermined value or more,
The engine with a supercharger according to claim 1, wherein the bypass passage is connected to the inner scroll chamber or the first exhaust passage so as to bypass the exhaust of the first exhaust passage.

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