JPS62121819A - Exhaust passage controller for engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of overcooling in exhaust gas and overheating in a catalyzer, by installing a low temperature service exhaust manifold and a high temperature service exhaust manifold provided with a liquid-cooled type cooling unit, and selecting the manifold that makes exhaust flow according to heating value of the exhaust gas. CONSTITUTION:An exhaust manifold is branched off to a low temperature service exhaust manifold 3a and a high temperature service exhaust manifold 3b, and a liquid-cooled type cooling unit 9 is installed in the high temperature service manifold 3b. IN addition, cutoff valves 4a and 4b are installed in these manifolds 3a and 3b, and a catalytic converter 8 is set up at the downstream side of these valves. And, and engine speed Ne and suction air quantity Q are detected, and the heating value is more than the specified value, the cutoff valve 4a is closed and the valve 4b is opened instead, making the exhaust flow into the high temperature service manifold 3b, cooling the cooling unit, thus overheating in the catalytic converter 8 is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exhaust gas flow path control device for an engine, and more particularly to an exhaust gas flow path control device suitable for an engine equipped with a catalytic converter in its exhaust system.

[Conventional technology]

The exhaust manifold that constitutes the exhaust system of an engine is affected by the heat of the exhaust gas, so sufficient consideration is given to its shape, material, etc. to prevent damage such as deformation and cracking due to heat. However, the amount of heat released from the outer surface of the exhaust manifold is quite high, and therefore it is necessary to take some measures to prevent this released heat from having an adverse effect on other parts. Conventionally, for this purpose, a heat shield plate has been passively provided around the exhaust manifold, and cooling fins have been proactively provided on the outer surface of the exhaust manifold (see Utility Model Application Publication No. 56-59920). reference). However, in the case of an air-cooled type such as the above-mentioned cooling fin, there is a problem in that a stable cooling effect cannot be obtained because the cooling performance depends on the running wind.

Therefore, the present applicant previously filed an application for an engine exhaust system cooling device that utilizes engine cooling water to obtain a stable cooling effect (Utility Model Application No. 106837/1983).

On the other hand, in order to make effective use of the advantages and disadvantages of the single exhaust system and dual exhaust system of the engine, a switching valve is provided near the inlet of two exhaust pipes installed in parallel, and the switching valve is adjusted according to the operating state of the engine. There is a known device in which the switch is switched (see Japanese Utility Model Application Publication No. 55-25602).

[Problem that the invention seeks to solve]

The above-mentioned water-cooled cooler opens the thermostatic valve when the cooling water temperature reaches a predetermined temperature and circulates the cooling water through the exhaust manifold. Constant cooling will be performed.

However, the exhaust temperature varies depending on the operating state of the engine. In other words, during idle operation or partial operation (low load operation), the amount of exhaust gas decreases and the exhaust temperature decreases, and conversely, during high load operation, the amount of exhaust gas increases and the exhaust temperature decreases. rises.

As a result, in the case of the above-mentioned water-cooled cooler, cooling is performed even though the exhaust temperature is low during engine idling operation and partial operation, and the catalytic converter has to perform proper purification performance. There is a risk that it will become inactive due to the temperature being out of range.

In this case, emissions will deteriorate due to an increase in GO-HC in the exhaust gas.

On the other hand, even if the engine operating conditions are the same (same - intake air amount), if you go to a high altitude, the air density is low, so the actual intake air amount decreases and the exhaust temperature decreases. Therefore, if the above-mentioned water cooling is performed under the same engine operating conditions (region) as on a flat ground, the exhaust temperature will drop too much, resulting in deterioration of emissions, as described above.

On the other hand, engine knocking generally occurs more often when the air-fuel ratio is lean or when the ignition timing is too advanced. Therefore, in order to prevent this, the air-fuel ratio is controlled to the rich side or the ignition timing is delayed.
If the cooling of the exhaust manifold is inappropriate, contrary to the above, the exhaust temperature will rise abnormally during high-load operation, causing the catalytic converter to heat up and lose reliability, which may result in insufficient purification performance. be.

In addition, the system disclosed in Japanese Utility Model Application Publication No. 55-25602 has both exhaust pipes depending on whether the exhaust pipe is simply one (single) or two (dual) depending on the operating condition of the engine. Although they are designed to compensate for each other's shortcomings, there is no mention of cooling at all, and no consideration is given to preventing deterioration of emissions due to a drop in exhaust temperature.

In light of the following, an object of the present invention is to provide an exhaust passage control device that can prevent overcooling of exhaust gas to prevent deterioration of emissions, as well as prevent heating of a catalytic converter and improve reliability. do.

[Means for solving problems]

In order to solve the above problems, the present invention provides an exhaust manifold that is branched into two systems, a high-temperature exhaust gas manifold and a low-temperature exhaust gas manifold, and is guided to a catalytic converter, and a high-temperature exhaust gas manifold. with a liquid-cooled gas cooler.

An exhaust gas control valve that selectively controls each passage of the high-temperature exhaust gas and low-temperature exhaust gas manifolds, and a valve control device that outputs a valve control signal that controls opening and closing of each of the control valves according to the amount of exhaust heat of exhaust gas. It is characterized by having the following.

[Effect]

According to the above configuration of the present invention, the control valves installed in each manifold are controlled to open and close depending on the operating state of the engine by the valve control signal from the valve control device depending on the amount of exhaust heat of the exhaust gas. Therefore, when the amount of exhaust heat is high, the control valve of one branched manifold for low-temperature exhaust gas is closed, and the control valve of the other manifold for high-temperature exhaust gas is opened, and the exhaust gas with high amount of exhaust heat is It will be led to the catalytic converter via the high temperature exhaust gas manifold. Therefore, since the high-temperature exhaust gas manifold is provided with a liquid-cooled exhaust gas cooling device, it can be appropriately cooled and prevent the catalytic converter from overheating.

In addition, when the exhaust heat value is low, contrary to the above, the control valve of the manifold for low-temperature exhaust gas is opened, and the control valve of the manifold for high-temperature exhaust gas is closed, and the exhaust gas with low exhaust heat value is transferred to the low-temperature exhaust gas. It will be led to the catalytic converter via the manifold. Therefore, since the low-temperature exhaust gas manifold is not cooled, it is directly guided to the catalytic converter, and it is possible to prevent deterioration of emissions due to deactivation of the catalyst without excessive cooling.

〔Example〕

Next, each embodiment according to the present invention will be described based on the drawings.

The first embodiment of Hoshigami Sueo M is shown in FIGS. 1 to 6. FIG. 1 shows an overall view of an engine including an exhaust passage control system according to the present invention. In FIG. 1, each exhaust port 2 of an engine 1 includes an exhaust manifold 3a for low-temperature exhaust gas (hereinafter referred to as a low-temperature exhaust manifold) and an exhaust manifold 3a for high-temperature exhaust gas (hereinafter referred to as a high-temperature exhaust manifold). ) 3b is connected, and consists of an exhaust manifold branched into two systems (see Figure 2). Each exhaust manifold 3a, 3b is provided with a low-temperature exhaust gas cutoff valve (hereinafter referred to as a low-temperature cutoff valve) 4a and a high-temperature exhaust gas cutoff valve (hereinafter referred to as a high-temperature cutoff valve) 4b as control valves. , these are opened and closed by a negative pressure valve 6 via a link 5.

Exhaust gas discharged via the low-temperature or high-temperature exhaust manifolds 3a, 3b is collected at a front pipe 7 and reaches a catalytic converter 8.

As shown in Figures 1 and 2, the exhaust manifold is divided into two systems directly from the exhaust port 2, but as shown in Figure 3, one manifold is connected to each exhaust port 2. 3c and may be divided into two at the middle.

A liquid-cooled exhaust gas cooling section 9 is provided in the high-temperature exhaust manifold 3b. In this embodiment, engine cooling water is used as the cooling fluid, and the cooling water sent out from the water pump 10 flows through the inside of the engine 1 and the cooling section 9. The cooling water that has exited the cooling unit 9 returns to the front of the thermostat 12 via the water bypass passage 11, and circulates through either the water pump 10 side or the radiator 13 side depending on the warm-up state of the engine 1.

The low-temperature cutoff valve 4a and the high-temperature cutoff valve 4b have a relationship such that when one is open, the other is closed, and their opening/closing operation is based on the engine rotation speed Ne and the engine rotation per engine load corresponding to the engine load. It is controlled based on the relationship with the intake air amount Q/N e (Fig. 6). That is, as shown in FIGS. 1 and 4, the engine speed Ne given by a pulse signal from the distributor 18 and the intake air amount Q given by an analog signal from the air flow meter 19 are input to the computer 20, and the Inside the computer 20, Q/N for the current Ne
The relationship between e is calculated. Then, the VSV 14 is controlled by the algorithm shown in FIG.

Now, referring to FIG. 5, assuming that the computer 20 has started, the computer 20 calculates Q for Ne.
/ Ne satisfies the condition for turning off the VSV 14 or not is determined in <Step 100>. At step 100>, the determination as to whether or not the condition for turning off the VSV 14 exists is made based on the map shown in FIG. The boundary between whether the VSV 14 is OFF or ON is determined empirically and experimentally based mainly on whether the catalytic converter 8 exhibits a predetermined purification performance and overheat prevention.

Now, in step 100>, if the OFF condition of ■sv is not satisfied (ON condition satisfied) (NO), the process proceeds to the next step 1o1>, and an ON control signal is sent to the VSV 14. The establishment of the VSV14 (7) ON condition means that the exhaust gas temperature is in a relatively low temperature range (idle operation, partial operation), so VSV14
Input negative pressure is introduced into the negative pressure valve 6 from the intake manifold 15 via the vacuum hose 17 and the vacuum surge tank 16 to open the low temperature cutoff valve 4a, while closing the high temperature cutoff valve 4b. As a result, exhaust gas from the exhaust port 2 is guided to the catalytic converter 8 via the low temperature exhaust manifold 3a. Therefore, the exhaust gas is not actively cooled and is maintained at a temperature appropriate for the activation of the catalytic converter 8, so that emissions do not deteriorate.

On the other hand, in <Step 100>, the OF of VSV14
If the F condition is satisfied (YES), proceed to step 102.
> and sends an OFF control signal to the VSV14. VSV
14 is satisfied, which means that the exhaust gas temperature is in a high temperature range (high load operation), therefore, vSv14 opens the negative pressure valve 6 to the atmosphere. Then, the low-temperature cutoff valve 4a is closed, while the high-temperature cutoff valve 4b is opened. As a result, the high temperature exhaust gas from the exhaust port 2 is guided to the catalytic converter 8 via the high temperature A exhaust manifold 36.

At this time, since the high-temperature exhaust manifold 3b is provided with the cooling section 9, the exhaust gas is guided to the catalytic converter 8 in a cooled state to an appropriate temperature. The catalytic converter 8 is thus prevented from overheating. Regarding emissions, since the exhaust gas is inherently high temperature, it is in the active region, so there is no problem.

The above control operations are summarized in Table 1 below.

Table 1 As mentioned above, according to this example, Ne and Q/
By predicting the engine exhaust temperature (calorific value) from the relationship of N e and controlling the shutoff valves 4a and 4b of each exhaust manifold 3a and 3b according to the temperature, the catalytic converter 8 can be overheated or deactivated. This can prevent deterioration of emissions.

Further, due to the cooling effect during high-load operation, it is no longer necessary to lower the exhaust temperature with the heat of vaporization of the fuel at an air-fuel ratio richer than the output air-fuel ratio, as in the conventional case, and fuel efficiency and output can be improved.

A second embodiment is shown in FIG. 7. In this embodiment, even if the operating state of the engine 1 is such that exhaust gas flows to the high temperature exhaust manifold 3b side, the shutoff valves 4a and 4b are immediately shut off. A predetermined delay time is set to prevent opening and closing of the gate. By doing so, each shutoff valve 4a,
It is possible to prevent harmful effects caused by repeated opening and closing of 4b. For example, as for this adverse effect, each cutoff valve 4a, 4
Examples include a decrease in reliability due to mechanical wear due to chattering, and a decrease in output due to disturbance of the flow of exhaust gas when instantaneous output is required during acceleration.

Next, a specific example will be described, and the same reference numerals will be given to the parts that overlap with those in the first embodiment, and the explanation thereof will be omitted, and the explanation will be made using the drawings.

This embodiment has basically the same configuration as the first embodiment, and similarly performs control based on the relationship between the engine speed Ne and the load Q/Ne. The difference is that, as shown in FIG. 7, when the VSV14 (7) OFF condition is satisfied (YES) in <Step 1oO>, an OFF control signal is given to the VSV14 to open the high temperature cutoff valve 4b and open the low temperature cutoff valve. Close 4a.

At that time, start the timer set in the computer 20 in step 1o3>, and then in step 104
>, it is determined whether t seconds have elapsed. That is, for example, if the delay time required during acceleration is set to seconds (e.g.
5 seconds), and after this delay time has elapsed, the process proceeds to <Step 101> and VsV14 is turned OFF. Note that the reason why the delay time is not set when the ON condition of the VSV 14 is established is that there is no need to perform the above-mentioned control from the viewpoint of transient phenomena. The other operations are the same as those in the first embodiment, so the explanation will be omitted.

However, a third embodiment is shown in FIGS. 8 to 11. This embodiment focuses on the fact that even if the engine operating conditions are the same (same Q/Ne), the actual amount of intake air differs between flatlands and highlands due to changes in air density. That is,
At high altitudes, the actual amount of intake air decreases, resulting in a drop in exhaust temperature. If the same engine operating conditions as in flatlands are used and the same cooling effect as in each of the above embodiments is performed, emissions will deteriorate due to supercooling of the exhaust gas temperature. This is because there is a risk of inviting

This embodiment compensates for the above-mentioned problem, and is used at high altitudes (low atmospheric pressure) where the exhaust temperature is difficult to rise due to a decrease in the amount of intake air even during high-speed, high-load operation.

The shutoff valves 4a and 4b are controlled so as to narrow the operating range (OFF range of the VSV 14) in which exhaust gas is routed to the high temperature exhaust manifold 3b side.

Next, this third embodiment will be explained in detail, but the basic configuration and control operation are the same as those of the first embodiment, and only specific points will be explained below.

The difference between FIG. 8 and FIG. 1 is that the computer 20
The point is that the output signal from the atmospheric pressure sensor 21 is used as an input signal to the atmospheric pressure sensor 21. This atmospheric pressure sensor 21 is used to determine whether the engine is operating in a flatland or a highland. Therefore, as shown in FIG.
An analog signal from the computer 20 is converted into a digital signal by an A/D converter and then input.

In this embodiment, the switching criteria for each of the shutoff valves 4a and 4b, and therefore the switching criteria for the VSV 14, are roughly divided into two criteria: level ground standard A and high ground standard B (FIG. 11). In other words, Q/Ne is higher in highlands than in flatlands.
This is because unless the engine is operated in this region, the necessary exhaust temperature cannot be obtained, leading to overcooling and worsening emissions. The standard atmospheric pressure is, for example, 620 mmHg. Control operations according to these two criteria are as follows.

In FIG. 10, the operating environment conditions of the engine are determined based on the detection signal from the atmospheric pressure sensor 21 (step 200).
It is judged by.

If it is a highland (YES), it is determined in step 2o1 whether or not the relationship between Ne and Q/Ne is in accordance with the highland reference date shown in FIG. If it is within the high altitude standard B (YES), the exhaust temperature is high enough because it is a high load operation, and therefore the VSV1 is determined by step 202).
An OFF control signal is output to turn 4 OFF. As a result, the high-temperature shutoff valve 4b opens, and the exhaust gas cooled by the cooling unit 9 via the high-temperature exhaust manifold 3b is guided to the catalyst converters 1-8, and the catalytic converter 8 is not overheated. Moreover, there is no deterioration in emissions. On the other hand, if it is not in the B region (NO) as determined in step 201, the exhaust temperature is low because it is low load operation, and therefore the 4JV is determined in step 203.
An ON control signal is output to turn on the S V 14. As a result, the low-temperature cutoff valve 4a opens, and the exhaust gas that has passed through the low-temperature exhaust manifold 3a is guided to the catalyst inverter 8. At this time, the exhaust gas is guided to the catalytic converter 8 without being cooled, so that the temperature necessary for purification is not lost, and sufficient purification performance can be ensured.

On the other hand, if the determination in step 200 is (No), it means that the land is flat;
> and judged according to standard A for level ground. If it is within the A region as determined in <Step 204>, the VSV 14 is turned off and cooled in Step 202>, and if it is not within the A region, the VSV 14 is
Sv14 is turned ON and cooling is not performed. Note that the control operation on this level ground is the same as in the first embodiment, so please refer to Table 1.

As described above, since the discrimination criteria are switched according to the operating environment of the engine (highlands, flatlands), it is possible to appropriately prevent overheating and prevent deterioration of emissions.

A fourth embodiment is shown in FIGS. 12 and 13. In this embodiment, the exhaust temperature of a supercharged engine is predicted based on whether or not it is in a supercharged state.

The VSV 14 is controlled to switch between the exhaust manifolds 3a and 3b.

In FIG. 12, a mechanical supercharger 25 is connected to the crank pulley 24 of the engine 1 via a belt 31, and is rotated as the engine 1 operates. engine 1
Whether the operating state of the mechanical supercharger 25 is a supercharging state or a non-supercharging state can be known from the signal (for example, positive pressure or negative pressure) of the intake pressure sensor 22 attached to the intake manifold 15. It can also be known from the operating conditions of the electromagnetic clutch 23 when the operation is performed by turning the electromagnetic clutch 23 ON-OFF using signals and outputs obtained from the distributor 18 and the aerometer 19. The rest of the configuration is the same as that in FIG. 1, so the explanation will be omitted.

Next, the control operation will be explained. In FIG. 13, whether or not the operating state of the engine is a supercharging state is determined based on the detection signal of the intake pressure sensor 22 in step 300>.

In the case of supercharging (positive pressure) (YES), turn off 5V14 in step 301 as the exhaust temperature will rise.
Then, the high-temperature exhaust valve 4b is opened to guide the exhaust gas to the high-temperature exhaust manifold 3b, where it is cooled by the cooling section 9.

On the other hand, if it is determined in step 300 that there is no supercharging (negative pressure) (No), the exhaust temperature will drop, so in step 302 the VSV14 will be changed to O1'I, low m e gas. Open the valve 4a and open the low temperature exhaust manifold 3a.
Do not conduct cooling by directing exhaust gas to the side.

In this way, protection of the catalytic converter 8 and normal purification function can be ensured even in an engine equipped with a supercharger. Although the supercharger has been described as a mechanical type, it goes without saying that a supercharger such as a turbocharger that uses exhaust gas can also be applied.

腅m舅- A fifth embodiment is shown in FIGS. 14 and 15.

In general, engines equipped with superchargers are prone to knocking. Also, when non-king occurs,
Ignition timing is often too advanced. Therefore, knock control is used to automatically control the delay of the ignition timing. However.

Delaying the ignition timing causes an increase in exhaust gas temperature, so if the engine is operated in this state, high-temperature exhaust gas will be sent to the catalytic converter 8.

As a result, problems may arise in terms of reliability, such as shortening of the life of the catalytic converter 8 due to overheating.

For this reason, in this embodiment, the amount of retardation of the ignition timing is used as a substitute for detecting the exhaust temperature, and the opening and closing of each of the shutoff valves 4a, 4b is controlled according to the detected amount, thereby opening and closing each of the exhaust manifolds 3a, 3b. The switch is configured to guide exhaust gas at an appropriate temperature to the catalytic converter 8.

Fig. 14 is a diagram showing an outline of an engine equipped with a mechanical supercharger, and the basic elements are the same as Fig. 12 (fourth embodiment) except for the following points, so the overlapping parts are the same. The following description will be given with reference numeral .

The difference between FIG. 14 and FIG. 12 is that knocking occurring in the engine 1 is detected by a knock sensor 29;
The computer 20 calculates the amount of retardation of the ignition timing based on the magnitude of the generated amount and supplies it to the distributor 18 via the igniter 26 and ignition coil 27. The point is that the VSV 14 is controlled by an algorithm. 28 is a spark plug.

FIG. 15 shows the number of each sensor and the relationship between the control equipment and the computer 20 for performing the above operations.

Next, the control operation will be explained based on FIG. 16.

The amount of retardation is calculated by the computer 20 based on the amount of knocking detected by the knock sensor 29.
A) It is determined whether or not it is greater than or equal to A).

If the retard amount is larger than the reference value A (YES), the exhaust gas temperature will increase, so the process goes to step 404 and the VSV
An OFF control signal is output to 14.

As a result, the high-temperature shutoff valve 4b side is opened, and the high-temperature exhaust gas is guided to the catalytic converter 8 via the high-temperature exhaust manifold 3b. At this time, since the cooling unit 9 is provided in the high temperature exhaust manifold 3b, the exhaust gas temperature is lowered, the catalytic converter 8 is not overheated, and the emissions are also good.

On the other hand, if the determination in <Step 400> is (NO), the VSV 14 is turned off in <Step 401>.
It is determined whether it is N or not, and if it is ON, it is left as is.

Therefore, the exhaust gas passes through the low temperature exhaust manifold 3a and reaches the catalytic converter 8. If the VSV 14 is 0FF (7) as determined in step 401>, the process proceeds to step 402>.

In step 402>, if the retard amount is equal to or greater than the second reference value B (for example, 3"CA) (YES) 1', <step 40
4>, VSV14 remains at 0FF (7). Second
If it is lower than the reference value B (No), the VSV 14 is turned on and the exhaust gas is guided to the catalytic converter 8 through the low temperature exhaust manifold 3a.

Note that the first reference value A and the second reference value B are used to determine the amount of retardation.
The reason for providing these two standards is to provide a hysteresis characteristic to prevent chattering caused by the ON-OFF operation of the VSV 14.

As described above, according to this embodiment, even if the amount of retardation associated with ignition timing control increases, the exhaust temperature can be appropriately cooled, and overheating of the catalytic converter can be prevented.

Kodan cusine five ■ A sixth embodiment is shown in FIGS. 17 and 18.

In this embodiment, the vSV 14 is controlled based on the exhaust temperature detected by the exhaust temperature sensor 30 provided in the catalytic converter 8 to control the opening and closing of the shutoff valves 4a and 4b, thereby switching the exhaust manifolds 3a and 3b. This is what I did.

The difference in FIG. 17 is that an exhaust gas temperature sensor 30 is provided in the catalytic converter 8, and the rest is the same as in FIG. 1 (first embodiment), so the same reference numerals are given and the explanation will be omitted.

The control operation will be explained with reference to FIG. Exhaust temperature sensor 30
The detected value from
An OFF control signal is output from VSV14. As a result, the high temperature cutoff valve 4b is opened, the exhaust gas is cooled by the cooling unit 9, and overheating of the catalytic converter 8 is prevented. When the temperature of the catalytic converter 8 decreases, an ON control signal is sent from the computer 2o to the VSV 14, but it does not turn ON immediately even if the temperature drops below the allowable temperature U.
The ON control signal is issued after the temperature reaches a predetermined temperature L (for example, 700° C.). The reason for providing such a hysteresis characteristic is to prevent chattering from occurring near the allowable temperature U.

In this way, according to this embodiment, the temperature of the catalytic converter 8 is directly detected to control the exhaust temperature.
The catalytic converter can be appropriately protected from overheating, and deterioration of emissions can also be effectively prevented.

In the first to sixth embodiments described above, the cooling section 9
Although the configuration uses the cooling water system of the engine, the application of the present invention is not limited to this, and the cooling section 9 can be configured with a separate independent cooling circuit. For example, a water-cooled intercooler is sometimes used in an engine equipped with a supercharger, and the cooling circuit of this intercooler can be used. Alternatively, a completely independent circuit may be used, and in that case, it can be realized by appropriately combining a subradiator of an appropriate size, a water pump, and the cooling section 9. Also, cooling water is not water;
Any suitable cooling liquid may be used.

Furthermore, in the first to seventh embodiments described above, both the low-temperature manifold 3a and the high-temperature manifold 3b were provided with cutoff valves 4a and 4b, respectively, but instead of this, one cutoff valve was provided at the junction of both exhaust manifolds. A switching valve may be provided to perform exhaust switching operation.

〔Effect of the invention〕

As explained above, according to the present invention, the exhaust manifold is branched into two systems, one for high temperature and one for low temperature, and a liquid cooling type cooling section is provided in the exhaust manifold for high temperature, so that the temperature of the exhaust gas itself or that corresponding to the exhaust temperature is By controlling the opening and closing of the shutoff valve provided in each exhaust manifold based on physical quantities, the exhaust manifold is switched to cool the exhaust gas, or to direct the exhaust gas to the catalytic converter without cooling it. In addition to preventing overheating of the engine, it is also possible to prevent deterioration of emissions due to a decrease in exhaust gas temperature due to overcooling.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an overview of the first embodiment of the present invention, FIG. 2 is a partially enlarged view showing the structure of the exhaust manifold in the first embodiment, and FIG. 3 is a branching mode of another exhaust manifold. FIG. 4 is a block diagram showing the configuration of the computer and its peripheral equipment in the first embodiment, FIG. 5 is a flowchart showing the control algorithm of the first embodiment, and FIG. 6 is a diagram showing the control algorithm of ■S■. It is an explanatory diagram showing operation judgment criteria. FIG. 7 is a flowchart showing a control algorithm showing a second embodiment. FIG. 8 is a schematic block diagram showing the third embodiment, FIG. 9 is a block diagram showing the relationship between the computer and its peripheral devices in the third embodiment, and FIG. 10 is a flowchart showing the control algorithm of the third embodiment. FIG. 11 is an explanatory diagram showing the vSv operation judgment criteria in the third embodiment. FIG. 12 is a schematic block diagram showing a fourth embodiment. FIG. 13 is a flowchart showing the control algorithm in the fourth embodiment. FIG. 14 is a schematic block diagram showing the fifth embodiment, FIG. 15 is a block diagram showing the relationship between the computer and its peripheral devices in the fifth embodiment, and FIG. 16 is a flowchart showing the control algorithm in the fifth embodiment. It is. FIG. 17 is a schematic block diagram showing the sixth embodiment, and FIG. 18 is an explanatory diagram showing the vSv control operation according to the sixth embodiment. 1...Engine, 2...Exhaust hoard, 3a...Exhaust manifold for low temperature. 3b...Exhaust manifold for high temperature, 4a...Shutoff valve for low temperature, 4b...Shutoff valve for high temperature. 5...Link, 6...Negative pressure valve, 7...Front pipe. 8... Catalytic converter, 9... Cooling section, 10...
Water pump, 11... water bypass path. 12...Thermostat, 13...Radiator, 1
4...Vacuum switching valve (VSV)
, 15...Intake manifold, 16...Vacuum surge tank. 17...Vacuum hose. 18...Distributor, 19...Affrometer, 20...Computer, 21...Atmospheric pressure sensor. 22... Intake pressure sensor, 23... Electromagnetic clutch, 2
4...Crank pulley, 25...Mechanical supercharger. 26...Ignaida. 27... Ignition coil, 28... Spark plug, 29... Knock sensor, 30
...Exhaust temperature sensor, Neo...Engine speed, Q...
...Amount of intake air.

Claims (10)

[Claims] (1) an exhaust manifold that is branched into two systems, a high-temperature exhaust gas manifold and a low-temperature exhaust gas manifold, and guided to a catalytic converter; and a liquid-cooled exhaust gas cooling device provided in the high-temperature exhaust gas manifold; an exhaust gas control valve that selectively controls each passage of the high-temperature exhaust gas manifold and the low-temperature exhaust gas manifold; and a valve control device that outputs a valve control signal that controls opening and closing of the control valve according to the amount of exhaust heat of exhaust gas. An engine exhaust passage control device comprising: (2) An engine exhaust passage control device according to claim 1, wherein the exhaust heat amount of the exhaust gas is determined by the intake air flow rate per engine revolution. (3) In the device according to claim 2, the valve control signal when opening the control valve of the high-temperature exhaust gas manifold and closing the control valve of the low-temperature exhaust gas manifold is generated after a predetermined delay time has elapsed. An engine exhaust passage control device characterized by transmitting information to each shutoff valve. (4) An engine exhaust passage control device according to claim 2 or 3, characterized in that the opening/closing control timing of each of the control valves is variably controlled based on atmospheric pressure. (5) In the device according to claim 1, when the engine is equipped with a supercharger, the exhaust heat amount of the exhaust gas is determined depending on whether it is in a supercharged state, and when the engine is in a supercharged state, An engine exhaust passage control device characterized by outputting a control signal that opens a control valve of a high-temperature exhaust gas manifold and, in a non-supercharging state, opens a control valve of a low-temperature exhaust gas manifold. (6) In the device according to claim 1, the exhaust heat amount of the exhaust gas is determined by a detected value of a temperature detector that detects the temperature of the catalytic converter, and when the detected value is high temperature, the high temperature exhaust gas Open the control valve of the manifold for
An engine exhaust passage control device characterized by outputting a control signal that opens a control valve of a low-temperature exhaust gas manifold when the temperature is low. (7) In the device according to claim 1, the exhaust heat amount of the exhaust gas is determined based on the magnitude of the ignition timing retardation amount in the knocking state of the engine, and when the retardation amount is large and when knocking is not occurring. Engine exhaust characterized by outputting a control signal that opens a control valve of a manifold for high-temperature exhaust gas when knocking occurs, and opens a control valve of a manifold for low-temperature exhaust gas when knocking does not occur and a retard amount is small. Aisle control device. (8) The device according to claims 1 to 7, characterized in that the exhaust gas cooling device is interposed in the cooling water system of the engine, so that the exhaust gas cooling device is cooled by the cooling water of the engine. Engine exhaust passage control device. (9) An engine exhaust passage control device according to claims 1 to 7, characterized in that the exhaust gas cooling device is constituted by a coolant circuit independent of the engine. (10) In the device according to claim 9, when the engine is equipped with a supercharger, the exhaust gas cooling device is configured to be interposed in the coolant circuit of the liquid-cooled intercooler. An engine exhaust passage control device characterized by: