JPH06200746A - Exhaust device for engine with pressure wave supercharger - Google Patents

Abstract

PURPOSE:To maintain the high supercharging efficiency of a supercharger so as to heighten responsiveness at the accelerating time of an engine and reduce a torque shock at the time of switching to steady operation from acceleration by switching gradually while raising the temperature or a catalyst by exhaust gas at the time or switching an exhaust gas passage to a catalyst passage from a by-pass passage. CONSTITUTION:Intake air in an intake passage 3 is supercharged in a pressure wave supercharger 6 by the pressure wave of exhaust gas in an exhaust passage 4. The exhaust passage 4 upstream of the pressure wave supercharger 6 is provided with a catalyst means 7 and a by-pass passage 10 by-passing the catalyst means 7, and the exhaust gas passage is switched by a passage switching means 25 provided with a catalyst side switching valve 11 and a by-pas side switching valve 12. When an engine is returned to steady operation after acceleration, the catalyst side switching valve 11 is gradually opened while the by-pass side switching valve 12 is gradually closed by the control of a control unit 31. In the accelerating state, the by-pass side switching valve 12 is fully opened while the catalyst side switching valve 11 is closed so as to supply the supercharger 6 with the exhaust gas not cooled by the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for a supercharged engine equipped with a pressure wave supercharger for supercharging intake air in an intake passage by pressure waves of exhaust gas.

[0002]

2. Description of the Related Art Generally, when an exhaust gas purifying catalyst device is arranged in an exhaust passage in order to meet the exhaust gas purifying requirements of an engine equipped with this type of pressure wave supercharger, the catalyst device is used. Purification performance depends on the exhaust gas temperature,
The higher the exhaust gas temperature, the higher the purification performance,
A catalyst device is arranged in the exhaust passage on the upstream side of the supercharger.

However, in that case, the heat of the exhaust gas is taken by the catalyst device, the temperature of the exhaust gas flowing to the supercharger is lowered, and the volume thereof is reduced, so that the efficiency of the supercharger is lowered, especially at the time of engine acceleration. There is a problem that the supercharging pressure by the supercharger is lowered and the acceleration response is deteriorated.

Therefore, in order to deal with such a problem, in the prior art, the one disclosed in Japanese Patent Laid-Open No. 4-140411 discloses an exhaust gas purification catalyst device arranged in an exhaust passage upstream of a pressure wave supercharger. The exhaust passage on the upstream and downstream sides is connected by a bypass passage, and a switching valve is provided to switch the passage so that the exhaust gas selectively flows to the catalyst device or the bypass passage, and the exhaust gas bypasses when the engine is accelerated. By switching the switching valve so as to flow into the passage, the response during acceleration is enhanced.

[0005]

However, even this conventional one is not completely free of problems. In other words, the responsiveness of the engine during acceleration can be maintained well, but in this accelerated state, exhaust gas flows through the bypass passage, so
During that time, the temperature of the catalyst device is lowered. Therefore, in order to return the engine to the steady operation state after the acceleration state, when the switching valve is switched so that the exhaust gas flows to the catalyst device, the low temperature exhaust gas passing through the catalyst device and cooled by For the same reason as above, the supercharging pressure of the supercharger drops and its performance deteriorates, and the output torque of the engine becomes insufficient, causing torque shock.

The present invention has been made in view of the above points, and an object of the present invention is to switch the exhaust gas flow path by changing the control mode when the engine returns from the acceleration state to the steady operation state. It is to eliminate the torque shortage that accompanies the output torque of the engine and suppress the torque shock.

[0007]

In order to achieve the above object, in the invention of claim 1, the exhaust gas flow path is switched from the bypass passage to the catalyst device by gradually switching the exhaust gas. It was decided to switch while raising the temperature of the catalyst.

That is, in the present invention, as shown in FIG. 1, as described above, the pressure wave supercharger 6 for supercharging the intake air in the intake passage 3 by the pressure wave of the exhaust gas in the exhaust passage 4.
An exhaust gas purifying catalyst means 7 disposed in the exhaust passage 4 on the upstream side of the pressure wave supercharger 6, a bypass passage 10 bypassing the catalyst means 7, and the exhaust gas being the catalyst means 7
Alternatively, it is premised on an exhaust device for an engine with a pressure wave supercharger, which is provided with a flow path switching means 25 for switching a flow path so as to selectively flow in the bypass passage 10.

The operating state detecting means 35 for detecting the operating state of the engine 1 and the above-mentioned flow so that the exhaust gas flows through the bypass passage 10 when the operating state detecting means 35 detects the accelerating state of the engine 1. Road switching means 2
5 is controlled at the first switching speed, and when the engine 1 returns from the accelerating state to the steady operating state, the flow passage switching means 25 is set at the first switching speed so that the exhaust gas flows through the catalyst means 7. And a control means 36 for controlling at a slower second switching speed.

According to a second aspect of the invention, in the exhaust system for an engine with a pressure wave supercharger according to the first aspect, a fuel injection amount varying means 5 for varying the fuel injection amount to the engine 1 is provided, and the control means 36 is provided. The fuel injection amount varying means 5 is controlled so that the fuel injection amount to the engine 1 is increased by a predetermined amount when the engine 1 returns from the acceleration state to the steady operation state.

According to the third aspect of the invention, the fuel injection timing changing means 5 for changing the fuel injection timing to the engine 1 is provided,
The control means 36, when the engine 1 returns from the accelerating state to the steady operation state, advances the fuel injection timing to the engine 1 by a predetermined value.
Is controlled.

[0012]

With the above construction, in the invention of claim 1, the operating state of the engine 1 is detected by the operating state detecting means 35, and when the operating state of the engine 1 is detected as the accelerating state, the control means 36 The flow path switching means 25 is controlled at the first switching speed so that the exhaust gas flows through the bypass passage 10. Due to the flow of the exhaust gas into the bypass passage 10 at the time of acceleration of the engine 1, the exhaust gas flows to the supercharger 6 at a high temperature without being cooled by the catalyst means 7, so that the supercharge efficiency of the supercharger 6 is improved. It can be kept large and the responsiveness at the time of engine acceleration can be improved.

On the other hand, thereafter, when the engine 1 returns from the acceleration state to the steady operation state, the control means 36 causes
The flow passage switching means 25 is controlled at a second switching speed lower than the first switching speed so that the exhaust gas flows through the catalyst means 7. At this time, since the switching speed of the flow path switching means 25 is slower than that at the start of acceleration, the exhaust gas gradually flows through the catalyst means 7 to increase the temperature, and the switching is performed while maintaining that state. As a result, the temperature change of the exhaust gas flowing through the supercharger 6 becomes gradual, the fluctuation of the supercharging efficiency of the supercharger 6 is small, and the fluctuation of the output torque of the engine 1 is small. Torque shock associated with switching to the operating state can be reduced.

According to the second aspect of the present invention, when the engine 1 returns from the acceleration state to the steady operation state, the control means 36 controls the fuel injection amount varying means 5 simultaneously with the switching control of the flow passage switching means 25. , The fuel injection amount to the engine 1 is increased by a predetermined amount. Due to this increase correction of the fuel injection amount, the exhaust gas temperature rises and the heating effect on the catalyst means 7 becomes high, and the temperature drop of the exhaust gas passing through this catalyst means 7 is suppressed to improve the supercharging efficiency of the supercharger 6. It is possible to suppress the torque shock caused by the switching, and it is possible to shorten the time until the completion of the switching.

According to the third aspect of the present invention, when the engine 1 returns from the accelerating state to the steady operating state, the control means 36 controls the fuel injection timing varying means 5 simultaneously with the switching control of the flow passage switching means 25, The fuel injection timing to the engine 1 is advanced by a predetermined value. Since the output torque itself of the engine 1 is increased by the advance correction of the fuel injection timing, the torque reduction due to the decrease in the supercharging efficiency of the supercharger 6 can be compensated by the amount of the torque increase. It is possible to effectively suppress the torque shock caused by the switching and shorten the time until the switching is completed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

(Embodiment 1) FIG. 4 shows the overall construction of Embodiment 1 of the present invention, wherein 1 is a diesel engine having four cylinders 2, 2, ... And 3 supplies intake air (air) to each cylinder 2. The intake passage 3 is connected to each cylinder 2 with its downstream portion branched into four, and the upstream end of the intake passage 3 is connected to an air cleaner (not shown). Reference numeral 4 denotes an exhaust passage for discharging the exhaust gas in each cylinder 2. The exhaust passage 4 has its upstream portion branched into four and connected to each cylinder 2. Reference numeral 5 denotes a fuel injection pump which is driven by the engine 1 to inject fuel into the cylinder 2 at an injection timing while pressurizing the fuel through a fuel injection nozzle (not shown). A fuel injection amount varying means and a fuel injection timing varying means for varying the timing are configured.

A pressure wave supercharger 6 for supercharging the intake air in the intake passage 3 by the pressure wave of the exhaust gas in the exhaust passage 4 is arranged between the respective collecting portions of the intake passage 3 and the exhaust passage 4. ing. As is well known, the supercharger 6 introduces a pressure wave of exhaust gas into the slit-shaped space from one end of the rotor, compresses the intake air in the space at the other end of the rotor, and continuously rotates the space to intake the intake air. It is supercharged.

An oxidation reaction catalyst device 7 for purifying exhaust gas is disposed in the exhaust passage 4 upstream of the pressure wave supercharger 6 and downstream of the branch portion. The catalyst device 7 has a housing 9 containing a carrier 8 made of a metal carrier carrying a catalyst.

Further, the exhaust passages 4, 4 on the upstream and downstream sides of the catalyst device 7 are connected by a bypass passage 10 bypassing the catalyst device 7. Further, the exhaust passage 4 on the upstream side of the catalyst device 7 downstream of the branch portion to the bypass passage 10
Is a butterfly-type catalyst-side on-off valve 11 for opening and closing the exhaust passage 4, and the bypass passage 10 is for the bypass passage 1
Similar bypass side opening / closing valves 12 for opening / closing 0 are provided respectively. The on-off valves 11 and 12 are connected by links 13 and 14 and a rod 15 so as to open and close in synchronization with each other in opposite directions. The end of the rod 15 is drivingly connected to a diaphragm type actuator 16. The actuator 16 is provided with a diaphragm 17 connected to the rod 15, a pressure chamber 18 defined by the diaphragm 17, and the pressure chamber 18, which is contracted, and the catalyst-side opening / closing valve 11 is provided via the diaphragm 17 and the rod 15. And a spring 19 for urging the bypass side opening / closing valve 12 in the valve closing direction. The pressure chamber 18 is connected to a three-way solenoid valve 21 via a pressure introducing passage 20.
1 is connected to a vacuum pump 23 via a negative pressure introduction passage 22 and is open to the atmosphere via an atmosphere opening passage 24. Then, the introduction of negative pressure or atmospheric pressure to the pressure chamber 18 of the actuator 16 is switched by the control of the three-way solenoid valve 21 so that the exhaust gas selectively flows through the catalyst device 7 or the bypass passage 10. A flow path switching device 25 for switching between the pressure chamber 1 of the actuator 16 and the three-way solenoid valve 21 is configured.
When 8 is switched to open to the atmosphere, atmospheric pressure is introduced into the pressure chamber 18 and the catalyst side opening / closing valve 11 is opened and the bypass side opening / closing valve 12 is closed by the atmospheric pressure and the biasing force of the spring 19. The bypass passage 10 is closed and exhaust gas is allowed to flow into the catalyst device 7. On the other hand, when the three-way solenoid valve 21 is switched so that the pressure chamber 18 communicates with the vacuum pump 23, a negative pressure is introduced into the pressure chamber 18 and the diaphragm 1
7 is biased against the urging force of the spring 19 to close the catalyst-side opening / closing valve 11 and open the bypass-side opening / closing valve 12 to fully open the bypass passage 10 to bypass exhaust gas to the catalyst device 7 to bypass the bypass passage 10 It is designed to be flushed to.

The operation of the fuel injection pump 5 and the three-way solenoid valve 21 is performed by receiving a control signal from the control unit 31. In the control unit 31, an output signal of an accelerator opening sensor 32 for detecting the opening of an accelerator pedal (not shown) and an exhaust passage 4 upstream of a branch portion to the bypass passage 10 are arranged and the catalyst device 7 is provided. An output signal of a catalyst upstream side exhaust temperature sensor 33 for detecting the exhaust gas temperature T1 on the upstream side and a catalyst for detecting the exhaust gas temperature T2 on the downstream side of the catalyst device 7 arranged in the exhaust passage 4 immediately downstream of the catalyst device 7. At least the output signal of the downstream side exhaust temperature sensor 34 is input.

In the control unit 31,
By controlling the three-way solenoid valve 21, both on-off valves 11,
A signal processing operation for controlling opening / closing of 12 will be described with reference to FIG. First, after initialization after the start, in step S1 the accelerator opening is detected based on the output signal of the accelerator opening sensor 32, and in step S2, the amount of change in the accelerator opening per constant time is set as a reference value. By comparing with, it is determined whether the engine 1 is in an accelerating state. When this determination is YES, in step S3, the three-way solenoid valve 21 of the flow path switching device 25 is switched in a short time (with the first switching time) so that the pressure chamber 18 of the actuator 16 communicates with the vacuum pump 23. Due to
The catalyst side opening / closing valve 11 is fully closed and the bypass side opening / closing valve 12
To open the bypass passage 10 immediately. afterwards,
In step S4, it is determined whether or not the engine 1 has returned to the steady operation state after acceleration. If this determination is NO, the process returns to step S3. When the engine 1 returns to the steady operation state and the determination in step S4 becomes YES, the three-way solenoid valve 21 is gradually opened in step S5 so that the pressure chamber 18 of the actuator 16 is opened to the atmosphere, that is, the first switching. By switching over the second switching time longer than the time, the catalyst side opening / closing valve 11 is gradually opened and the bypass side opening / closing valve 12 is gradually closed to close the bypass passage 10, and at the same time, in step S6, the fuel injection pump 5 From the fuel injection amount to each cylinder 2 for a predetermined time t
Only increase correction. Thereafter, in step S7, it is determined whether or not the absolute value | T1-T2 | of the difference between the exhaust gas temperatures T1 and T2 detected by the exhaust temperature sensors 33 and 34 has become equal to or less than the reference value T0. Is | T1-T2
When |> T0 is NO, the process returns to step S5. When the determination is YES in the case of | T1−T2 | ≦ T0, it is considered that the degree of decrease in the temperature of the exhaust gas passing through the catalyst device 7 has become equal to or less than the predetermined value, and the process proceeds to step S8 to set the three-way solenoid valve 21 to the actuator 16. By completely switching the pressure chamber 18 to the atmosphere, the catalyst-side opening / closing valve 11 is fully opened and the bypass-side opening / closing valve 12 is fully closed, so that the bypass passage 10 is closed.

When the determination in step S2 is NO (when it is determined that the engine 1 is in the steady operation state), the process directly proceeds to step S8, the catalyst side opening / closing valve 11 is fully opened and the bypass side is opened. The on-off valve 12 is fully closed and the bypass passage 10 is fully closed.

In this embodiment, step S of the above flow is performed.
1 and S2 form an operating state detecting means 35 for detecting the operating state of the engine 1.

Further, when the acceleration state of the engine 1 is detected by the operating state detecting means 35 in steps S3 to S7, the flow passage switching device 25 is immediately (first) so that the exhaust gas flows through the bypass passage 10. At a switching speed of 1)
On the other hand, when the engine 1 returns from the acceleration state to the steady operation state while controlling, the flow passage switching device 25 is gradually moved to the exhaust gas so that the exhaust gas flows through the catalyst device 7 (the second switching speed slower than the first switching speed). Control means 36 for controlling the fuel injection pump 5 as the fuel injection amount varying means so that the fuel injection amount to the engine 1 is increased by a predetermined amount.
Is configured.

Therefore, in the above-described embodiment, during the operation of the engine 1, the change amount of the accelerator opening detected by the accelerator opening sensor 32 in the control unit 31 per unit time is compared with the reference value, and the engine 1 is operated. When the presence or absence of the acceleration state is determined, and when it is determined that the engine 1 is in the steady operation state, the three-way solenoid valve 21 is switched so that the pressure chamber 18 of the actuator 16 is opened to the atmosphere, and the catalyst side opening / closing valve 11 Is in a fully open state, the bypass side on-off valve 12 is in a fully closed state, and the bypass passage 10 is closed. As a result, the exhaust gas flows through the catalyst device 7, where it is oxidized and purified.

On the other hand, as shown in FIG. 2, when it is determined that the engine 1 is in the accelerated state, at the same time, first, the pressure chamber 18 of the actuator 16 is moved to the vacuum pump 23.
The three-way solenoid valve 21 is switched so that the bypass side opening / closing valve 12 is fully opened and the catalyst side opening / closing valve 11 is fully closed to maximize the opening of the bypass passage 10 (see FIG. 2 ( See a)). As a result, the exhaust gas bypasses the catalyst device 7 and bypass passage 10
The exhaust gas of high temperature that is not cooled by the catalyst device 7 is directly supplied to the supercharger 6 via the bypass passage 10, whereby the supercharging efficiency of the supercharger 6 is kept large. The acceleration response of the engine 1 can be improved.

Then, when the engine 1 returns from the acceleration state to the steady operation state thereafter, the three-way solenoid valve 21 is gradually switched so that the pressure chamber 18 of the actuator 16 is opened to the atmosphere. As a result, the catalyst-side opening / closing valve 11 gradually opens and the bypass-side opening / closing valve 12 gradually closes, so that the bypass passage 10 closes at a slower speed than during acceleration (see FIG. 2A). Further, as shown in FIG. 2B, the fuel injection amount supplied from the fuel injection pump 5 to each cylinder 2 is increased and corrected for a predetermined time t.

At this time, the three-way solenoid valve 21
Since the switching speed is lower than that at the start of acceleration of the engine 1, the exhaust gas gradually flows to the catalyst device 7 to increase its temperature, and the switching is performed in that state. As a result, the temperature change of the exhaust gas flowing to the supercharger 6 becomes gentle, the fluctuation of the supercharging efficiency of the supercharger 6 is small, the fluctuation of the output torque of the engine 1 is small, and the steady state from the acceleration state of the engine 1 is maintained. Torque shock associated with switching to the operating state can be reduced.

Moreover, at the same time as the switching control of the three-way solenoid valve 21 of the flow path switching device 25, the fuel injection amount injected from the fuel injection pump 5 into each cylinder 2 of the engine 1 is also increased. The exhaust gas temperature rises and the heating effect on the catalyst device 7 increases due to the increase correction of the above, the temperature drop of the exhaust gas passing through the catalyst device 7 can be suppressed, and the supercharging efficiency of the supercharger 6 can be improved. . Therefore, the torque shock associated with the switching can be suppressed more effectively, and the time until the switching is completed can be shortened.

Thereafter, the absolute value of the difference between the exhaust gas temperatures T1 and T2 detected by the exhaust temperature sensors 33 and 34, respectively |
When T1−T2 | falls below the reference value T0, it is considered that the temperature drop of the exhaust gas due to the catalyst device 7 has subsided,
The switching of the three-way solenoid valve 21 is completed so that the pressure chamber 18 of the actuator 16 is opened to the atmosphere. As a result, the catalyst side opening / closing valve 11 is fully opened and the bypass side opening / closing valve 12 is fully closed, the bypass passage 10 is closed in the original fully closed state, and the exhaust gas flows through the catalyst device 7 and is purified. .

(Embodiment 2) FIG. 5 shows Embodiment 2 (note that
The same parts as those in FIG. 4 are designated by the same reference numerals and detailed description thereof will be omitted), and the structure of the catalyst device 7'is changed.

That is, in this embodiment, the catalyst device 7 '
The carrier 8'is a ceramic carrier 8a 'housed in most of the housing 9 from the upstream end to the downstream side in the housing 9 and a metal carrier arranged only in the downstream end in the housing 9. It has a two-layer structure composed of 8b '. The mesh roughness of the metal carrier 8b 'is finer than that of the ceramic carrier 8a'.

In the case of this embodiment, most of the carrier 8'of the catalyst device 7'is the ceramic carrier 8a 'having a large heat capacity, so that the catalyst temperature is maintained at a high temperature even if the operating condition of the engine 1 changes. As a result, the temperature change can be reduced, and even when the engine 1 returns from the accelerated state to the steady operation state, the catalyst temperature can be effectively prevented from lowering, and the torque shock can be further reduced.

Further, since the metal carrier 8b 'having a smaller mesh roughness than that of the ceramic carrier 8a' is arranged on the downstream side of the ceramic carrier 8a ', the ceramic carrier 8a' should be damaged by heat or impact. Even if it does, it is possible to prevent the broken pieces from being caught by the metal carrier 8b 'and to be scattered to the supercharger 6 on the downstream side, and to prevent damage to the supercharger 6 and the like.

In the above embodiment, when the engine 1 is returned from the acceleration state to the steady operation state, the fuel injection amount to the engine 1 is increased and corrected. The fuel injection pump 5 may be controlled so as to advance the timing by a predetermined value. In this case, since the output torque of the engine 1 itself increases due to the advance correction of the fuel injection timing, the torque reduction due to the decrease in the supercharging efficiency of the supercharger 6 can be compensated by the amount of the torque increase. It is possible to effectively suppress the torque shock caused by, and to shorten the time until the completion of switching. Further, such advance correction of the fuel injection timing can be combined with the increase correction of the fuel injection amount.

[0037]

As described above, according to the invention of claim 1, an exhaust gas purification catalyst is provided in the exhaust passage upstream of the pressure wave supercharger for supercharging the intake air in the intake passage by the pressure wave of the exhaust gas. Means is provided and a bypass passage for bypassing the catalyst means is provided, and the engine is accelerated with respect to the exhaust device of the engine equipped with the pressure wave supercharger in which the exhaust gas passage is selectively switched to the catalyst means or the bypass passage. In the state, the exhaust gas is switched in a short time so as to flow through the bypass passage, while when the engine returns from the acceleration state to the steady operation state, the exhaust gas flows at a slower speed than the above switching speed so as to flow through the catalyst means. By gradually changing the engine, it is possible to ensure good responsiveness during engine acceleration, and when switching to steady operation, gradually discharge exhaust gas through the catalyst means. It performs a switching while reducing the temperature rise,
It is possible to reduce the temperature change of the exhaust gas flowing to the supercharger to reduce the fluctuation of the supercharging efficiency of the supercharger, and reduce the torque shock that accompanies the change from the engine acceleration state to the steady operation state.

According to the second aspect of the invention, when the engine returns from the acceleration state to the steady operation state, the fuel injection amount to the engine is increased by a predetermined amount at the same time as the switching control of the exhaust gas passage to the catalyst means side. By doing so, the exhaust gas temperature is positively increased to enhance the heating effect on the catalyst means, the temperature drop of the exhaust gas passing through this catalyst means is suppressed, and the supercharging efficiency of the supercharger is improved. It is possible,
It is possible to more effectively suppress the torque shock caused by the switching, and it is possible to shorten the time until the switching is completed.

According to the third aspect of the present invention, when the engine returns from the acceleration state to the steady operation state, the fuel injection timing to the engine is advanced, so that the output torque of the engine itself is increased. It is possible to compensate for torque down due to a decrease in supercharging efficiency of the feeder, and thus, similarly to the above, it is possible to effectively suppress the torque shock due to switching,
The time until the switching is completed can be shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a timing chart showing changes in various state quantities during engine acceleration according to the first embodiment of the present invention.

FIG. 3 is a flowchart schematically showing a signal processing operation performed by the control unit for controlling both open / close valves.

FIG. 4 is an explanatory diagram showing the overall configuration of the first embodiment.

FIG. 5 is a schematic sectional view of a catalyst device according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Cylinder 3 Intake passage 4 Exhaust passage 5 Fuel injection pump (fuel injection amount varying means, fuel injection timing varying means) 6 Pressure wave supercharger 7, 7'catalyst device (catalyst means) 10 Bypass passage 11 Catalyst side Open / close valve 12 Bypass side open / close valve 16 Actuator 21 Three-way solenoid valve 25 Flow path switching device (flow path switching means) 31 Control unit 35 Operating state detection means 36 Control means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display area F02D 41/04 335 F 8011-3G 43/00 301 T 7536-3G H 7536-3G J 7536-3G

Claims (3)

[Claims] 1. A pressure wave supercharger for supercharging intake air in an intake passage by a pressure wave of exhaust gas in an exhaust passage, and a catalyst means for exhaust purification arranged in an exhaust passage upstream of the supercharger. And an exhaust gas of a pressure wave supercharger engine including a bypass passage for bypassing the catalyst means and a flow passage switching means for switching a flow passage so that exhaust gas selectively flows through the catalyst means or the bypass passage. In the apparatus, an operating state detecting means for detecting an operating state of the engine, and the flow path switching means for allowing the exhaust gas to flow through the bypass passage when the operating state detecting means detects the acceleration state of the engine. While controlling at the switching speed, when the engine returns from the accelerating state to the steady operating state, the flow path switching means is switched to the second switching speed slower than the first switching speed so that the exhaust gas flows through the catalyst means. Exhaust system of the pressure wave supercharger with the engine, characterized in that a control means for controlling a speed. 2. The exhaust system for an engine with a pressure supercharger according to claim 1, further comprising a fuel injection amount varying means for varying a fuel injection amount to the engine, wherein the control means keeps the engine steady from an accelerating state. Exhaust of a pressure wave supercharged engine, characterized in that the fuel injection amount varying means is controlled so as to increase the fuel injection amount to the engine by a predetermined amount when returning to the operating state. apparatus. 3. The exhaust system for an engine with a pressure wave supercharger according to claim 1, further comprising a fuel injection timing changing means for changing a fuel injection timing to the engine, wherein the control means is an acceleration state of the engine. From the fuel injection timing varying means for advancing the fuel injection timing to the engine by a predetermined value when returning from the normal operation state to the pressure wave supercharger. Exhaust system of the engine.