JPH0893458A - Exhaust emission control device - Google Patents

Abstract

PURPOSE: To provide a self-diagnostic function excellent in the failure of a device by providing a failure diagnosing device to make a judgement that the device is failured when the temperature rise speed of an adsorption device in the gas adsorption process is below the set value, and the temperature rise speed in the gas elimination process is above the upper limit value or below the lower limit value. CONSTITUTION: An exhaust emission control device is provided with a first main flow passage 31 provided with a catalytic device 21 to control the exhaust gas of an automobile, an adsorption flow passage 33 provided with an adsorbing device 22 to adsorb the harmful gas, and a second main flow passage 32 to form a flow passage parallel to this flow passage 33. A return flow passage 35 to form a flow passage leading to the upstream side of the catalytic device 21 is provided, and flow passage opening/closing means 23, 24 to open/close the respective flow passages 32, 33, 35 are provided. In a failure diagnosing device 10, the temperature of the adsorbing device 22 is measured, and a judgement of the failure is made when the temperature rise speed is below the set value in closing the return flow passage 35, and a judgement of the failure is made when the temperature rise speed is above the upper limit value or below the lower limit value in opening the return flow passage 35.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust emission control device for an engine.

[0002]

2. Description of the Related Art As one method for purifying exhaust gas from an automobile, there is an exhaust gas purifying method using a catalyst device carrying a precious metal (platinum, rhodium, etc.) as a catalyst. For purification of HC by this method, the catalyst activation temperature is generally 350 ° C.
You need more than that. However, immediately after the engine is started, the catalyst has not reached the catalyst activation temperature, so that there is a problem that HC purification is hardly performed.

In order to solve the above problems, a catalyst device is provided in the exhaust system of the engine, and HC discharged during cold engine (hereinafter referred to as cold HC) is adsorbed on the upstream side or the downstream side thereof. H containing the adsorbent
Purification devices equipped with a C trapper have been proposed (JP-A-4-17710, JP-A-4-311618, JP-A-5-149130, and JP-A-5-25).
6124, JP-A-6-101452, etc.).

Japanese Unexamined Patent Publication No. 4-17710 and Japanese Unexamined Patent Publication No. 4-17710
In the exhaust gas purification device according to Japanese Patent No. 311618, an HC trapper containing an adsorbent is arranged downstream of the catalyst device in parallel with the main flow passage, and an adsorption flow passage containing the HC trapper and a main flow passage are respectively provided. A switching valve is provided. Then, the flow passage switching valve is operated for a predetermined time immediately after the engine is started to flow the exhaust gas into the adsorption flow passage, during which cold HC is adsorbed by the HC trapper.

On the other hand, at the time of high temperature when cold HC is desorbed from the adsorbent, the flow path switching valve is operated so as to flow the exhaust gas into the main flow path, and at this time, the downstream side of the HC trapper and the engine intake pipe are connected. Negative pressure in the intake pipe of the engine is applied to the HC desorption pipe, and the desorbed HC is sucked into the intake pipe and burned again in the engine.

Further, Japanese Patent Application Laid-Open No. 4-31618 describes a method of forcibly returning the desorbed HC to the upstream side of the catalyst by using a suction pump. In addition, Japanese Patent Laid-Open No. 5-1
In the exhaust gas purifying apparatus of Japanese Patent No. 49130 and Japanese Unexamined Patent Publication No. 5-256124, an adsorbing device using a zeolite-based adsorbent is arranged on the upstream side of a catalytic device, and the adsorbing device and the catalytic device are used in combination to reduce the exhaust gas temperature. Sometimes, the adsorbent adsorbs cold HC, and when the exhaust gas temperature is high, the HC desorbed from the adsorbent and the exhaust HC from the engine are purified by a catalyst device.

In the exhaust gas purifying apparatus according to Japanese Patent Laid-Open No. 6-101452, a bypass passage having an adsorbing device and a main passage having no adsorbing device are provided downstream of the catalyst device, and the adsorbing device is further provided. An exhaust gas temperature sensor is provided at each of the inlet and the outlet. Then, when the exhaust gas is at a low temperature, the amount of heat of adsorption when the harmful components are adsorbed by the adsorber is obtained, and if the amount of heat of adsorption does not reach the target value, it is determined that the adsorber is out of order.

[0008]

However, the conventional exhaust emission control device has the following problems. That is, there is no means for detecting the deterioration of the adsorbent or the malfunction of the flow path switching. Therefore, even after the failure of the exhaust gas purifying apparatus as described above, the exhaust gas purifying apparatus continues to be used as it is, so that a problem occurs that harmful gas is discharged. In addition,
In the exhaust gas purification device disclosed in Japanese Patent Laid-Open No. 6-101452, unlike the above-mentioned conventional device, a failure diagnosis device is provided, so that a certain kind of failure can be detected. However,
In the exhaust gas purification device disclosed in Japanese Patent Laid-Open No. 6-101452, a valve or a valve for circulating adsorbed harmful components to the upstream side of the catalyst device can be used even if deterioration or malfunction of the adsorbent can be diagnosed. With regard to malfunctions of devices related to moving parts such as bypass passage switching valves, malfunction diagnosis is impossible at all, and the diagnosis function is insufficient. In view of such problems, the present invention is to provide an exhaust gas purification device having an excellent self-diagnosis function for device failure and having good exhaust gas purification characteristics.

[0009]

A first invention of the present application is an exhaust gas purification device provided in an exhaust passage of an engine, wherein the exhaust gas purification device is located upstream of the exhaust passage and purifies exhaust gas. A first main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful gas, and an adsorption flow path located downstream of the first main flow path. A second main channel forming a channel parallel to the channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a branch from the adsorption channel to the upstream side of the catalyst device. A return flow path forming a flow path, a flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a device malfunction A failure diagnosis device for diagnosing, and the adsorption flow in the return flow path. Is provided with a directional valve that allows only the flow of exhaust gas from the exhaust gas to the upstream of the catalyst device, and the controller operates the flow path opening / closing means to the first operation state when the exhaust gas is at a low temperature, thereby causing the return operation. Exhaust gas that has closed the flow path and passed through the adsorption flow path is circulated to the exhaust flow path, and blocks the flow of exhaust gas from the second main flow path to the exhaust flow path. The flow passage opening / closing means is operated to the second operation state, whereby exhaust gas is circulated from the second main flow passage to the discharge flow passage, and the return flow passage is opened to return the exhaust gas passing through the adsorption flow passage. Flow through the passage and block the flow of exhaust gas from the adsorption passage to the discharge passage, the failure diagnosis device measures the temperature of the adsorption device, and in the first operating state, the temperature rise rate is When the value is less than the set value It is determined that location failure,
In the second operating state, there is provided an exhaust gas purification device, characterized in that the exhaust gas purification device has a judging means for judging that the device has failed when the temperature rising rate is equal to or higher than a predetermined upper limit value or lower than a predetermined lower limit value. .

The first point that is most noticeable in the first aspect of the invention is that when the temperature of the exhaust gas is low, the return flow path is closed and the exhaust gas that has passed through the adsorption flow path is circulated to the exhaust flow path.
Blocks the flow of exhaust gas from the main flow path to the exhaust flow path,
Operating the passage opening / closing means in the so-called first operating state,
When the exhaust gas is at a high temperature, the exhaust gas is circulated from the second main flow channel to the exhaust flow channel, the return flow channel is opened, and the exhaust gas passing through the adsorption flow channel is circulated to the return flow channel. Cut off the flow of exhaust from the passage to the exhaust passage,
Operating the flow path opening / closing means in the so-called second operation state.

The second point that is most noticeable in the first invention is that it has a failure diagnosis device, which measures the temperature of the adsorption device and, in the first operating state, the above If the temperature rise rate is less than or equal to the set value, it is determined that the device is faulty, and in the second operating state, if the temperature rise rate is equal to or higher than a predetermined upper limit or lower than the lower limit, it is determined to be the device fault. Is.

Next, a second invention of the present application is an exhaust gas purification device provided in an exhaust passage of an engine, wherein the exhaust gas purification device is located upstream of the exhaust passage and purifies exhaust gas. A first main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and an adsorption flow path located downstream of the first main flow path. A second main channel forming a channel parallel to the channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a branch from the adsorption channel to the upstream side of the catalyst device. A return flow path forming a flow path, a flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a device malfunction A failure diagnosis device for diagnosing, and the adsorption flow in the return flow path. Is provided with a directional valve that allows only the flow of exhaust gas from the exhaust gas to the upstream of the catalyst device, and the controller operates the flow path opening / closing means to the first operation state when the exhaust gas is at a low temperature, thereby causing the return operation. Exhaust gas that has closed the flow path and passed through the adsorption flow path is circulated to the exhaust flow path, and blocks the flow of exhaust gas from the second main flow path to the exhaust flow path. The flow passage opening / closing means is operated to the second operation state, whereby exhaust gas is circulated from the second main flow passage to the discharge flow passage, and the return flow passage is opened to return the exhaust gas passing through the adsorption flow passage. The exhaust flow from the adsorption flow path to the discharge flow path is cut off, and the failure diagnosis device measures the flow rate of the exhaust gas passing through the adsorption device. When the value falls below the set value In the second operating state, there is a determining means for determining that the device is in failure when the passage flow rate is equal to or more than a predetermined upper limit value or less than a predetermined lower limit value. Exhaust gas purification device.

A second aspect of the present invention is an exhaust emission control device which is different from the exhaust emission control device of the first aspect of the present invention in a failure diagnosis device. That is, the failure diagnosis device in the second aspect of the invention measures the flow rate of the exhaust gas passing through the adsorption device, determines that the device failure has occurred in the first operating state when the above-mentioned flow rate is below a set value, and
In the operating state, it is determined that the device is faulty when the passing flow rate is equal to or higher than a predetermined upper limit value or lower than a predetermined lower limit value.

Next, a third invention of the present application is an exhaust gas purification device provided in an exhaust passage of an engine, wherein the exhaust gas purification device is located upstream of the exhaust passage and purifies exhaust gas. A first main flow path, a suction flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and a suction flow path located downstream of the main flow path. A second main flow path forming a parallel flow path, and an exhaust flow path located downstream of the adsorption flow path and the second main flow path,
A return flow channel that branches from the adsorption flow channel and forms a flow channel that reaches the upstream side of the catalyst device, a flow channel opening / closing unit that opens and closes the adsorption flow channel, the second main flow channel, and the return flow channel, and the flow channel. It has a controller for controlling the passage opening / closing means and a failure diagnosis device for self-diagnosing malfunctions of the device, and allows only the exhaust flow from the adsorption flow path to the upstream of the catalyst device in the return flow path. A directional valve is provided, and the controller operates the flow passage opening / closing means to a first operating state when the exhaust gas has a low temperature, whereby the return flow passage is closed and the exhaust gas that has passed through the adsorption flow passage. To the exhaust flow path and block the flow of exhaust gas from the second main flow path to the exhaust flow path, while the exhaust gas is at a high temperature, the flow path opening / closing means is operated to the second operating state. As a result, the second main channel is drained. Exhaust gas is allowed to flow through the flow path, and the return flow path is opened to allow the exhaust gas that has passed through the adsorption flow path to flow through the return flow path to block the flow of exhaust gas from the adsorption flow path to the exhaust flow path. The device measures the concentration of a predetermined exhaust gas in the exhaust flow passage, and the exhaust gas concentration becomes a value equal to or higher than a set value set to a different value in the first operating state and the second operating state. In this case, there is provided an exhaust emission control device having a determination means for determining that the device has failed.

A third invention is an exhaust emission control device having a failure diagnosis device different from the failure diagnosis devices of the first and second inventions.
That is, the failure diagnosis device according to the third aspect of the present invention measures a predetermined exhaust gas concentration in the exhaust flow passage, and determines that the device is in failure when the exhaust gas concentration becomes equal to or higher than a set value. The set value is different in the first operating state and the second operating state.

A fourth invention of the present application is an exhaust gas purification device provided in an exhaust passage of an engine, wherein the exhaust gas purification device is a catalyst device located upstream of the exhaust passage for purifying exhaust gas. A first main flow path provided, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and an adsorption flow path located downstream of the first main flow path A second main flow path forming a parallel flow path, an exhaust flow path located downstream of the adsorption flow path and the second main flow path, and a branch from the adsorption flow path to reach the upstream side of the catalyst device. A return flow path forming a flow path, a flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a self-diagnosis of a device failure And a suction diagnostic flow path in the return flow path. A directional valve that allows only the flow of exhaust gas from the upstream side of the catalyst device to the catalytic device is provided, and the controller operates the flow path opening / closing means to the first operation state when the exhaust gas is at a low temperature, thereby causing the return operation. Exhaust gas that has closed the flow path and passed through the adsorption flow path is circulated to the exhaust flow path, and blocks the flow of exhaust gas from the second main flow path to the exhaust flow path. The flow passage opening / closing means is operated to the second operation state, whereby exhaust gas is circulated from the second main flow passage to the discharge flow passage, and the return flow passage is opened to return the exhaust gas passing through the adsorption flow passage. And a return flow rate calculating means for calculating the exhaust flow rate of the return flow path from the operating state of the engine, and the return flow path. The above discharge gas in Means for measuring the concentration of the exhaust gas and integrating the total amount of exhaust gas that has passed through the return flow path in the second operation state, and determining means for determining the device failure when the total integrated amount of exhaust gas is less than or equal to a set value. And an exhaust emission control device.

A fourth invention is an exhaust emission control device having a failure diagnosis device different from the failure diagnosis devices of the first to third inventions.
That is, the failure diagnosing device of the fourth aspect of the invention includes a return flow rate calculating means for calculating the exhaust flow rate Q _r of the return flow path from the operating state of the engine, and a concentration of the exhaust gas in the return flow path to measure the second operating state. In the above, there is provided an integrating means for integrating the total amount W of exhaust gas that has passed through the return flow path, and a determining means for comparing the integrated total amount W of exhaust gas with a set value W _o to judge a malfunction of the apparatus.

The return flow rate Q _r can be calculated from, for example, a parameter indicating the flow rate of engine exhaust and the operating state of the engine.
It can be calculated according to a certain formula. The integrating means includes, for example, an integrator that integrates the product of the output C _{r of the} exhaust gas sensor and the return flow rate Q _r during the second operation state (W _r = ∫C _r Q _r dt). .

In the third and fourth aspects of the invention, the failure diagnosis device further measures the temperature of the adsorption device, and determines whether the rate of temperature rise is above a set value in the first operating state, and whether or not the temperature rises. It is preferable to provide second determining means for determining whether or not the speed is equal to or lower than a predetermined upper limit value or a predetermined lower limit value in the second operating state.

By providing such a second judging means, as will be described later in the next section, it becomes possible to know whether or not there is a leakage of a predetermined value or more in the flow path, and thereby the failure diagnosis device (main This is because it is possible to elucidate whether the cause of the failure determined by the determination means) is due to the leakage of the flow path opening / closing means. As a result, the repair work for the failure can be made easier.

Further, in the third and fourth inventions, the failure diagnosis device further measures an exhaust flow rate passing through the adsorption device, and determines whether the passage flow rate is less than or equal to a set value in the first operating state. Further, it is preferable to provide a third determination means for determining whether or not the flow rate of flow is equal to or more than a predetermined upper limit value or less than a predetermined lower limit value.

By providing such a third judging means, it is possible to know whether or not there is a leakage of a predetermined value or more in the exhaust passage or whether the return passage is blocked, as will be described later in detail. This is because it becomes possible and the cause of the failure judged by the failure diagnosis device can be clarified in the same manner as above. As a result, the repair work of the failure becomes easy.

Next, a fifth invention of the present application is an exhaust gas purification device provided in an exhaust passage of an engine, wherein the exhaust gas purification device is located upstream of the exhaust passage and purifies exhaust gas. A first main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful gas, and an adsorption flow path located downstream of the first main flow path. A second main channel forming a channel parallel to the channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a branch from the adsorption channel to the upstream side of the catalyst device. A return flow path forming a flow path, a flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a device malfunction A failure diagnosis device for diagnosing, and the adsorption flow in the return flow path. Is provided with a directional valve that allows only the flow of exhaust gas from the exhaust gas to the upstream of the catalyst device, and the controller operates the flow path opening / closing means to the first operation state when the exhaust gas is at a low temperature, thereby causing the return operation. The flow path is closed and the exhaust gas passing through the adsorption flow path is circulated to the exhaust flow path and the flow of the exhaust gas from the second main flow path to the exhaust flow path is blocked, while at the time of high temperature of the exhaust gas, The flow path opening / closing means is operated to the second operating state, whereby exhaust gas is circulated from the second main flow path to the exhaust flow path, and the return flow path is opened to return the exhaust gas that has passed through the adsorption flow path. The exhaust flow from the adsorption channel to the exhaust channel is blocked, and the failure diagnosis device measures the exhaust temperature of each of the downstream side of the adsorption device and the return channel. In the second operating state above, Exhaust gas purification characterized by having a determination means for calculating the degree of correlation between two exhaust temperatures and determining that the device failure has occurred when the degree of correlation does not reach a certain level On the device.

The fifth invention is another exhaust gas purification apparatus having a failure diagnosis apparatus different from the first to fourth inventions. That is, the fifth
The failure diagnosis device according to the invention measures the exhaust temperature of each of the downstream side of the attachment device and the return flow path, and calculates the degree of the correlation between the two exhaust temperatures in the second operating state. A device is provided for judging that the device is faulty when the degree of this correlation does not reach a certain level. In the above, the index for calculating the degree of correlation includes, for example, a correlation ratio and a correlation coefficient. As will be described later in detail, the failure diagnosis device according to the fifth aspect of the present invention is particularly excellent in the function of detecting the failure of the directional valve in the return passage.

In the fifth aspect of the invention, the failure diagnosis device further measures the temperature of the adsorption device and determines whether or not the rate of temperature rise is above a set value in the first operating state, and whether or not the temperature rises. It is preferable to provide fourth determining means for determining whether or not the speed is equal to or higher than a set value in the second operating state. By providing such a fourth determining means, it becomes possible to determine whether or not there is a leakage of a predetermined value or more in the opening / closing means of the main flow passage, and the cause of the failure is clarified, as will be described later in detail. Because it will be ready. Therefore, the repair work of the failure becomes easy.

Further, in the fifth aspect of the invention, the determination means calculates the degree of correlation between the two exhaust temperatures and determines that the device is in failure, when the second operation state is set. It is preferable that the condition is that the engine is idling or the vehicle is decelerating. By adding the condition that the vehicle is idling to the condition, the judgment time can be shortened, and by adding the condition that the vehicle is in the decelerating condition, the correlation value can be more clearly separated depending on the presence or absence of a failure. .

[0027]

[Operation and effect] First, the operation and effect of the first invention will be described. When the exhaust gas is at a low temperature, the flow path is in the first operating state, and all the exhaust gas flows from the adsorption flow path to the exhaust flow path. Therefore, toxic exhaust gas such as HC that is not purified by the catalyst device because the exhaust gas is low in temperature is adsorbed by the adsorption device (toxic gas adsorption step). Therefore, harmful exhaust gas is not emitted to the outside.

On the other hand, when the temperature of the exhaust gas becomes high, the flow path is switched to the second operation state, the exhaust gas forms two flows, and one of the exhaust flow flows from the second main flow path to the exhaust flow path to the outside. Is discharged to (dangerous gas desorption process). Since the exhaust gas is hot, harmful exhaust gas is purified by the catalyst device.

The other exhaust flow flows from the adsorption flow path to the return flow path. With this high temperature exhaust flow,
The exhaust gas adsorbed by the adsorption device is desorbed and introduced into the upstream of the catalyst device through the return passage. Then, the exhaust gas is purified by the catalyst device. As described above, by switching the flow path opening / closing means to the first and second operating states in accordance with the temperature of the exhaust gas, it is possible to suppress the external discharge of the exhaust gas of the engine, and the exhaust gas having a good exhaust gas purification characteristic. A purification device can be obtained.

On the other hand, the failure diagnosis device measures the temperature in the adsorption device and calculates the rising speed V _t thereof. The velocity V _t can be easily calculated by a method such as performing a differential operation on the measured temperature value. Then, the rising rate V _t in the first operation state, as shown in FIG. 5, to be gradually reduced by leakage that does not pass through the suction passage flow rate Q _a (FIG. 4) is known.

Therefore, the magnitude of the leakage flow rate Q _a can be known by knowing the V _t . That is, as shown in FIG. 5, when V _t is equal to or less than the predetermined value V _t0 , the leak flow rate Q _a from the flow path opening / closing means is at least the set value Q _a0.
It can be determined that the above.

A large leakage flow rate Q _a means that a large amount of exhaust gas is discharged without being adsorbed by the adsorption device, as indicated by the broken line in FIG. 4, so that the leakage flow rate Q _a becomes a predetermined value Q _a0 . Exceeding this can be determined to be a failure state of the exhaust purification device.

On the other hand, in the second operating state, the temperature rising rate V _td is the leakage flow rate Q _d leaking from the adsorption flow path to the discharge flow path.
(FIG. 4) changes as shown in FIG. Therefore,
Since it is possible heating rate V _td is determined that the flow rate Q _d leakage have to be the upper limit value V _t1 more exceeds the upper limit leakage flow Q _d0, thereby determining a failure of the device in the harmful gas desorption step You can This is because there is a large amount of the leakage flow rate Q _d because the exhaust gas desorbed from the adsorption device is discharged to the outside through the discharge flow path.

Further, in the harmful gas desorption process, the return flow passage Q _r (FIG. 4) is reduced due to the occurrence of problems such as blockage in the return flow passage from the adsorption flow passage to the upstream of the catalyst device via the return flow passage. There is. When the reflux flow rate Q _r decreases, the temperature rising rate V _td decreases as shown in FIG. Therefore, since the rate of temperature increase V _td is equal to or lower than the lower limit value V _t2 , it can be considered that the reflux flow rate Q _r is too small (Q _r ≤Q _r0 ), that is, the device is out of order.

This is because if the return flow rate Q _r is insufficient, the exhaust gas desorbed by the adsorption device cannot be purified by the catalyst device and leaks to the outside together with the exhaust gas. As described above, the failure diagnosis device of the present invention can self-diagnose the device failure due to the leakage or blockage of the exhaust passage by monitoring the temperature rising rates V _t and V _td as described above. Exhaust gas purification characteristics can always be kept good. As described above, according to the first aspect of the present invention, it is possible to provide an exhaust gas purification device having a self-diagnosis function and excellent exhaust gas purification characteristics.

Next, the function and effect of the second invention will be described. In the exhaust gas purifying apparatus according to the second invention fault diagnosis apparatus for measuring the flow rate Q _t of exhaust gas passing through the adsorption apparatus.
Then, the flow rate through Q _t in the first operation state (hazardous gas adsorption step), as shown in FIG. 10, it changes according to the magnitude of the leakage flow rate Q _a leaking from the second main flow passage (Fig. 4). That is, with the flow rate Q _t is equal to or smaller than the set value Q _0, it is possible to know the leakage flow rate Q _a is the predetermined value Q _a0 above, (emission of polluting emissions) failure of the exhaust gas purifier as Can be detected.

On the other hand, the second operating state (toxic gas desorption process)
In the above, the passing flow rate Q _td changes as shown in FIG. 11 depending on the leak flow rate Q _d (FIG. 4) leaking from the adsorption flow path to the discharge flow path. That is, since the exhaust flow rate _Qtd in the second operating state is the upper limit value Q ₁ or more, the leakage flow rate Q _d is the upper limit value Q _d0 or more, and as described above, the device malfunctions (leakage of polluted exhaust gas). Can be detected.

Further, as described above, when the return flow rate Q _r in the second operating state is equal to or lower than the lower limit value Q _r0, it is possible to know the malfunction (blockage, etc.) of the return passage. Then, in the second operating state, the passing flow rate Q _td and the return flow rate Q _r
12 has a relationship as shown in FIG. 12, it is possible to detect whether the passing flow rate Q _td is equal to or less than the lower limit value Q ₂ and determine the device failure. As described above, according to the failure diagnosis apparatus of the second invention, it is possible to detect the apparatus failure due to the leakage or blockage of the exhaust passage. For others, first
It is similar to the invention.

Next, the function and effect of the third invention will be described.
In the exhaust emission control device according to the third aspect of the present invention, the concentration C of a predetermined exhaust gas such as HC in the exhaust passage is measured. On the other hand, the concentration C of the exhaust gas increases due to a decrease in the adsorption capacity of the adsorption device or a malfunction of the exhaust gas purification device due to leakage of exhaust gas that does not pass through the adsorption device.

That is, in the first operating state (adsorption step) when the exhaust emission control device is normal, as shown in FIG. 15, the exhaust gas concentration (HC in FIG. 15) at the outlet of the engine shown by the broken line is As shown by the solid curve, the discharge flow path has a large decrease. Therefore, when the average value of the exhaust gas concentration C in the exhaust passage is smaller than the set value C _a , it can be determined that the exhaust purification device is out of order.

Similarly, in the second operating state (desorption process), as shown in FIG. 16, the concentration C of the exhaust gas (HC in FIG. 16) becomes an extremely small value as shown by the solid curve. From the above, it can be determined that the exhaust purification device has a failure when the average value of the concentration C is larger than the set value C _d . Further, in the failure diagnosis device of the present invention, the exhaust gas concentration C in the first operating state and the second operating state is the set value C.
_a, it determines the failure of the exhaust gas purification apparatus to monitor whether a C _d or more.

In the present invention, since the concentration C of the exhaust gas in the exhaust passage is directly measured, it is possible to detect a failure due to a failure such as a leak in the exhaust passage as in the first and second inventions, and to detect the adsorption device. It is also possible to detect a failure in the case of a failure due to a decrease in adsorption capacity. Others are the same as the first invention.

Next, the function and effect of the fourth invention will be described.
In the exhaust emission control device according to the present invention, the return flow rate Q _r in the return flow path is calculated, and the concentration C _{r of the} exhaust gas in the return flow path is measured to measure the total amount W (return amount) of the exhaust gas in the second operating state. ), And a determining means for comparing the return amount W with a set value W _o and determining a failure of the exhaust gas purification device.

If the exhaust gas purifying device is normal, FIG.
As shown in 0, the return amount W exceeds the set value W _o , but if the exhaust purification device fails for some reason,
The return amount W becomes the set value W _o or less. Therefore, both W and W ₀
The difference or ratio is calculated, and when this difference or ratio reaches a predetermined value (W−W ₀ ≧ 0, or W ₀ / W ≧ 1), the determination means determines that the exhaust gas purification device has a failure. be able to.

As described above, in the case of the fourth aspect of the invention, the return amount W is calculated and the quality of the exhaust gas purification device is judged when one cycle consisting of the first operating state and the second operating state is completed. Others are the same as the third invention.

The exhaust emission control device according to the third and fourth inventions, as described in claim 4 or 5, is the same as the second or the same second one used in the failure diagnosis device of the first invention or the second invention. It is preferable to use the determination conditions of 3 together. As a result, it is possible to more reliably determine the failure, and it is also possible to determine whether the cause of the failure is due to a defect in the exhaust passage or a characteristic failure of the adsorption device. Then, by determining the cause of the failure in this way, the failure can be easily repaired.

Next, the function and effect of the fifth invention will be described.
In the exhaust emission control device according to the fifth aspect of the present invention, the temperatures Tri and Tre of the exhaust gas flowing respectively on the downstream side of the adsorption device and the return passage are measured in the second operating state. The temperatures Tri and Tre of the exhaust gas have a strong correlation with each other when the directional valve of the return passage and the operating means for operating the directional valve (for example, the opening / closing means and the solenoid valve) are operating normally. It is known to have (see FIG.
3). On the other hand, it is known that when a failure occurs in the directional valve of the return flow path, the operating means for operating the directional valve, or the like, the correlation between the temperatures Tri and Tre is largely lost (described later). (See FIG. 25).

Therefore, the failure diagnosing device has the temperatures Tri and Tre.
The device failure can be determined based on the correlation between the two. Further, in the present invention, since the temperature of the exhaust gas flowing on the downstream side of the adsorption device is measured, as described in the description of the first invention, the flow passage for opening and closing the adsorption flow passage and the second main flow passage. The failure of the opening / closing means can also be determined.
The failure of the flow path opening / closing means is possible in both the first operating state and the second operating state.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 An exhaust gas purification apparatus according to an embodiment of the first invention is shown in FIGS.
This will be described with reference to FIG. As shown in FIG. 1, this example is an automobile exhaust emission control device 1 provided in an exhaust passage of an engine 51. The exhaust gas purification device 1 is provided with a first main flow passage 31 located upstream of the exhaust passage and provided with a catalyst device 21 for purifying exhaust gas, and an adsorption device located downstream of the first main flow passage 31 for adsorbing harmful gas. Adsorption channel 33 with device 22;
A second main channel 32 that is located downstream of the first main channel 31 and forms a channel parallel to the adsorption channel 33, and an adsorption channel 33.
And a discharge flow path 34 located downstream of the second main flow path 32
And a return channel 35 that branches from the adsorption channel 33 and forms a channel that reaches the upstream side of the catalyst device 21, and the channels 32 and 3
It has flow path opening / closing means 23, 24 for opening / closing 3, 35, a controller 41 for controlling the flow path opening / closing means 23, 24, and a failure diagnosis device 10 for self-diagnosing malfunctions of the device.

Then, in the return flow path 35, the adsorption flow path 33
A directional valve 25 is provided that allows only the flow of exhaust gas from the upstream side to the upstream side of the catalyst device 21 to pass therethrough. When the temperature of the exhaust gas is low, the controller 41 operates the flow path opening / closing means 23, 24 to the first operation state, thereby closing the return flow path 35 and the exhaust gas passing through the adsorption flow path 33 to the exhaust flow path 34. The flow of the exhaust gas from the second main flow path 32 to the exhaust flow path 34 is cut off while being circulated. Further, when the temperature of the exhaust gas is high, the controller 41 operates the flow path opening / closing means 23, 24 to the second operation state, whereby the exhaust gas is circulated from the second main flow path 32 to the exhaust flow path 34 and returned. The flow path 35 is opened, the exhaust gas passing through the adsorption flow path 33 is circulated to the return flow path 35, and the flow of exhaust gas from the adsorption flow path 33 to the discharge flow path 34 is blocked.

On the other hand, the failure diagnosing device 10 includes the suction device 22.
The temperature was measured, in the first operating state, it is determined to be a device failure if the rising speed V _t of the temperature is equal to or smaller than the set value V _t0, in the above-described second operating state, the Atsushi Nobori It has a determination means for determining that the device is in failure when the speed V _t is equal to or higher than a predetermined upper limit value V _t1 or lower than a predetermined lower limit value V _t2 .

A supplementary explanation will be given below for each of these. As shown in FIG. 1, the catalyst device 21 is arranged in the exhaust pipe of the engine 51 immediately after the exhaust manifold 52. Further, a large diameter portion is provided in the exhaust pipe downstream of the catalyst device 21, and an adsorption flow path 33 accommodating the adsorption device 22 and a second main flow path 32 are formed therein. The adsorption device 22 is made of a ceramic such as stainless steel or cordierite, has a semi-cylindrical shape that matches the diameter of the large diameter portion, and has a large number of parallel through holes 221 as shown in FIG. A zeolite-based adsorbent is carried on the carrying layer 222.

The suction device 22 may have an elliptical shape or a rectangular shape according to the shape of the large diameter portion. Then, as shown in FIG. 1, a first flow path opening / closing means 23 is arranged immediately after the rear end of the adsorbent carrying layer 222 of the adsorption device 22. The distance between the catalyst device 21 and the adsorption device 22 depends on the timing at which the catalyst device 21 is heated by the exhaust gas to reach the activation temperature and the timing at which the adsorbent carried by the adsorption device 22 is heated and loses the adsorption function. The distances are set so that they almost match.

The adsorption device 22 is separated and held between the second main flow path 32 and the partition wall 223. Partition 2
As shown in FIG. 2, the hole 23 is provided in the hole 23. Further, as shown in FIG. 2, a flow straightening plate 225 is provided on the upstream side of the adsorption device 22 to make the flow velocity distribution of the exhaust gas flowing through the adsorption device 22 uniform and enhance the adsorption efficiency.

The partition wall 223 and the flow regulating plate 225 may have an integral structure as shown in FIG. 2 or may be separated. Further, as shown in FIG. 1, a temperature sensor 15 constituting the failure diagnosis device 10 is provided inside the adsorption device 22 to monitor the temperature of the adsorption device 22. The temperature sensor 15 may be provided anywhere inside the adsorption device 22, or may be behind the adsorption device 22 and in front of the flow path opening / closing means 23.

Then, the return flow path 35 branches from a position near the rear end of the adsorption flow path 33, and the return flow path 35 controls the flow of exhaust gas in the pipe in one direction and the second flow path opening / closing means. It has a reed valve 26 in which 24 is integrated and communicates with the exhaust manifold 52. The first flow path opening / closing means 23 is provided with an actuator 231.
1 is connected to the blade 230 of the first flow path opening / closing means 23 by the shaft 232.

The actuator 231 passes through intake pipes 361 and 362 for supplying a negative pressure for operating it,
It communicates with a surge tank 53 located upstream of the engine 51. The first solenoid valve 27 is arranged between the intake pipes 361 and 362. The directional valve 25 allows only the flow of exhaust gas from the return passage 35 toward the upstream side of the catalyst device 21.

The second flow path opening / closing means 24 is operated by a diaphragm or the like which operates with negative pressure. The flow path opening / closing means 24 communicates with the intake pipe 362 that connects the first electromagnetic valve 27 and the surge tank 53 by the intake pipes 371 and 372 that supply a negative pressure to the intake pipe 371, and between the intake pipes 371 and 372. Is provided with a second solenoid valve 28.

The controller 41 is composed of the microcomputer 40 and the control program shown in FIG. 3, receives signals from the engine 51 and the temperature sensor 15, and controls the opening and closing of the solenoid valves 27 and 28 according to the operating state. The flow path opening / closing means 23, 24 are controlled. In addition, the failure diagnosis device 1
0 consists of the microcomputer 40 and the failure diagnosis program shown in FIG.

Next, referring to FIG.
And will be described with reference to the flowchart of FIG. In step 601, the engine is started (IG = ignition).
When it is confirmed to be ON, the process proceeds to step 602. In step 602, the signal from the temperature sensor 15 is received, the value of the temperature T thereof is checked, and it is determined whether or not the adsorption by the adsorption device 22 is possible.

When the engine is cold started, the adsorption device 22 is cold, and the temperature T (° C.) is the adsorbable temperature T.
_{If it is a} (° C.) or less, the adsorption process proceeds to step 603 and subsequent steps, and the first solenoid valve 27 is opened in step 603,
The intake pipes 361 and 362 communicate with each other. As a result, the negative pressure of the surge tank 53 acts on the actuator 231 via the intake pipes 362 and 361 to pull the shaft 232, and the first flow path opening / closing means 23 moves to the position shown by the broken line in FIG. ).

Immediately after the cold start of the engine 51, the exhaust gas temperature is low, and the engine 51 discharges the exhaust gas containing a large amount of cold HC. While the exhaust gas temperature is low, the catalyst device 21 does not reach the activation temperature, so that the cold HC flows through the first main flow path 31 without being purified by the catalyst device 21.

This exhaust gas flow flows from the adsorbent-free layer 229 (FIG. 2) that does not support zeolite in the adsorption device 22 to the adsorbent-supporting layer 220 that supports zeolite, and cold HC is adsorbed by the adsorbent. It And cold HC
The exhaust gas from which is removed is discharged into the atmosphere through the exhaust passage 34. At this time, since the straightening plate 225 straightens the flow of the exhaust gas, the exhaust gas has a uniform flow velocity distribution,
It flows in the adsorption device 22.

While adsorbing the cold HC as described above, the adsorbing device 22 is heated by the exhaust gas. At this time, the leakage flow rate Q _a of the flow path opening and closing means 23 as shown in FIG. 4 is increased, the amount of exhaust gas flowing through the adsorbing device 22 is reduced, the heating rate V _t is delayed. as a result,
As shown in FIG. 5, the temperature rising rate V _t of the adsorption device 22 becomes smaller than that when there is no leakage flow rate Q _a .

The temperature rising rate V _t can be calculated from the signal from the temperature sensor 15. The above leakage flow rate Q _a is the actuator 2
31, the shaft 232 will be increased when such blade 230 is damaged, the leakage flow rate Q _a may exceed the allowable value Q _a0, heating rate V _t of the adsorber 22 becomes less than the allowable value V _t0.

Then, the amount of cold HC adsorbed is reduced, and the overall purification capacity is reduced. This defect is shown in Figure 5.
It can be determined by the fact that V _t becomes smaller than V _t0 as shown in FIG. That is, in step 604, if the temperature increase rate V _t is equal to or lower than V _t0, it is determined that the exhaust purification device 1 is out of order, and in step 605, the first solenoid valve 2 is operated.
7 is closed to enter the second operation state (steady operation state). Then, in step 606, the failure information is output. Through the series of processes described above, it is possible to diagnose the presence or absence of a device failure in the harmful gas adsorption process.

On the other hand, when the engine 51 warms up and the temperature T exceeds the HC adsorbable temperature T _a of the adsorption device 22 in step 602, the process proceeds to step 610 and the first
The solenoid valve 27 is closed. This allows the actuator 2
The supply of the negative pressure to 31 is cut off, and the actuator 231
Pushes the shaft 232 by the elastic force of the built-in spring.

Therefore, the first flow path opening / closing means 23 is in the solid line position (flow path opening / closing means 23 open position), the flow path of the exhaust gas is switched, and flows through the second main flow path 32 where the adsorption device 22 does not exist. At this time, the catalyst device 21 has already reached the activation temperature, and the HC in the exhaust gas remains in the catalyst device 2.
The exhaust gas which is purified by 1 and contains almost no HC is discharged from the second main flow path 32 to the atmosphere through the discharge flow path 34.

Then, in steps 611 to 613, the next operation is continued until the temperature T of the adsorption device 22 reaches a value exceeding the desorption purification finishing temperature T _d . That is, immediately after the first electromagnetic valve 27 is closed, the value of the temperature sensor 15 is read, the temperature T of the adsorption device 22 is monitored, and step 6
If the value T is less than or equal to the above T _{d in} 11, the second solenoid valve 28 is opened in step 612. As a result, the suction pipe 272 and the suction pipe 271 communicate with each other, negative pressure is supplied from the surge tank 53 to the second passage opening / closing means 24, and the passage opening / closing means 24 opens.

On the other hand, on the side surface of the adsorption device 22, the exhaust gas which has already become hot flows through the second main flow path 32. Exhaust gas of this temperature is used for the holes 2 of the partition wall 223 shown in FIG.
It is in contact with the adsorbent support layer 220 of the adsorption device 22 via 24. Therefore, the heat of the exhaust gas is absorbed by the adsorbent support layer 220.
The temperature of the adsorbent rises and the desorption of HC is promoted.

At this time, as described above, the flow path opening / closing means 24
Since the valve is open, the exhaust pulsation generated in the exhaust manifold 52 causes the directional valve 25 to be intermittently opened via the return passage 35. As a result, the HC desorbed from the adsorbent of the adsorbent carrier layer 220 of the adsorbing device 22 flows into the exhaust manifold 52 via the return flow path 35. And engine 51
It is purified by the catalyst device 21 together with HC in the exhaust gas from.

Then, as shown in FIG. 6, the flow path opening / closing means 2
If the leakage flow rate Q _d from FIG. 3 (FIG. 4) is the allowable value Q _d0 or more, the temperature rising rate V _td of the adsorption device 22 becomes the allowable value V _t1 or more. That is, when the actuator 231, the shaft 232, the blade 230, etc. are damaged, the leakage flow rate Q _{d
Exceeds the} allowable value _Qd0 , and exhaust gas flows through the discharge passage 34 at a flow rate higher than the normal flow rate.

Further, the amount of HC returned to the catalyst device 21 is reduced, and the overall purification capacity is reduced. This is Figure 6
It can be judged by the fact that V _td becomes V _t1 or more as shown in FIG. That is, since the result of step 613 is NO (no), it can be determined that the device is in failure.

Even if the actuator 231, the shaft 232, and the blade 230 of the flow path opening / closing means 23 are operating normally, if the reed valve 26 fails, the catalyst device 2
The exhaust gas flow rate Q _r (FIG. 4) recirculated to 1 decreases.
Then, the heat transfer to the adsorption device 22 becomes poor, and the V
_td becomes low. That is, the return flow Q _r becomes equal to or less than the allowable value Q _r0, as shown in FIG. 7, heating rate V _td allowable value V
It becomes less than _t2 . Therefore, even if the reed valve 26 fails, V
It can be detected when _td becomes V _t2 or less.

That is, when it is determined NO in step 613, the second solenoid valve 2 is operated in step 614.
8 is closed to bring it to a steady state, and device failure information is output in step 606. After the flow path opening / closing means 23 is switched to the open position (shown by the solid line) to enter the HC desorption purification step,
When the condition of step 613 is normally satisfied,
Eventually, in step 611, the temperature reaches the temperature T _{d at} which the desorption and purification of HC is completed (T> T _d ), and the routine proceeds to step 615, where the second electromagnetic valve 28 and the flow passage opening / closing means 24 are closed to enter a steady operating state.

As described above, in the exhaust emission control device 1 of this example,
Release of cold HC is prevented even when the engine is cold until the catalyst reaches the activation temperature. And in this device 1,
Even when adsorbing cold HC adsorbent, even when for desorption purifying HC, can be failure diagnosis device 10 is self-diagnosis device failure by monitoring the heating temperature V _t of the adsorption device 22. As described above, according to this example, it is possible to provide the exhaust gas purification device 1 having a self-diagnosis function of the device and having excellent exhaust gas purification characteristics.

Example 2 In this example, as shown in FIG. 8 and FIG.
It is the Example of the 2nd invention which changed the failure diagnostic apparatus 11.
That is, as shown in FIG. 8, the failure diagnosis device 11 of this example is
A differential pressure gauge 16 for measuring the differential pressure across the adsorption device 22 is provided to measure the flow rate Q _t through the adsorption device 22 and to diagnose the failure of the exhaust gas purification device 1 according to the failure diagnosis flowchart shown in FIG. .

Differences between the first embodiment and the present embodiment will be mainly described with reference to the system configuration diagram of FIG. 8 and the flowchart of FIG. A manometer (differential pressure gauge) 16 is provided inside the adsorption device 22, and a through hole 221 of the adsorption device 22 is provided.
The differential pressure of the exhaust gas flowing through (Fig. 2) is monitored.

First, when the engine 51 is started (IG.ON) in step 601, the controller 41 receives signals from an engine water temperature sensor and an exhaust temperature sensor (not shown), and determines whether or not adsorption by the adsorption device 22 is possible. That is, in step 621, for example, if the value T _w (° C.) of the water temperature sensor is equal to or lower than the adsorbable temperature T _wa (° C.),
The process proceeds to the steps following step 603. In step 603, the first electromagnetic valve 27 is opened, the exhaust gas flows through the adsorption device 22, and the cold HC in the exhaust gas is adsorbed.

In the following step 623, the time t after the engine is started is checked, and when the predetermined time (ta) has elapsed, the adsorption process is completed, the process proceeds to step 610, and the first signal is sent from the controller 41. The solenoid valve 27 is closed, and the flow path opening / closing means 23 is switched to the steady position indicated by the solid line. Then, the catalyst device 21 that has already become hot and activated
The exhaust gas from which the HC has been purified flows through the second main flow path 32.

On the other hand, at step 623, the predetermined time t
If it is determined that the value has not reached a, the adsorption process is continued. Since the exhaust gas is flowing through the adsorption device 22 while adsorbing the cold HC, the manometer 16
A differential pressure is generated at. This pressure difference is because having a constant relationship between the exhaust gas flow rate Q _t flowing through the suction device 22, whereby it is possible to know the flow rate Q _t.

When the leakage flow rate Q _a (FIG. 4) from the flow path opening / closing means 23 increases, the Q _t decreases as shown in FIG. 10 (the total amount Q _{E of} exhaust gas discharged from the engine is (Because it is Q _t + Q _a ). If the actuator 231, shaft 232, if such blade 230 is damaged, the Q _a is equal to or greater than the allowable value Q _a0. Then, as shown in FIG. 10, Q _t becomes Q ₀ or less, the amount of cold HC adsorbed decreases, and the overall purification capacity decreases. That is, if the conditions are satisfied in step 624, it can be determined that the exhaust emission control device 1 has failed.

When the condition of step 624 is satisfied, the routine proceeds to step 605, where the first electromagnetic valve 27 is closed to bring it to a steady state, and then, at step 606, the information of the device failure is output. On the other hand, in step 623, when the predetermined time ta has elapsed after the engine has been started as described above, the engine is in a warmed-up state, and thus the process proceeds to step 610 as described above to close the first solenoid valve 27. Valve to enter the desorption process.

Then, in the following step 612, the controller 41 opens the second electromagnetic valve 28. As a result, like the first embodiment, the second flow path opening / closing means 24 is opened,
The directional valve 25 is opened intermittently, and the HC desorbed from the adsorbent flows into the exhaust manifold 52 and is purified by the catalyst device 21 together with the HC in the exhaust gas from the engine 51.

Next, at step 632, the time t after the start of operation is checked again. Then, after the opening of the second solenoid valve 28, the time until the HC is completely desorbed and purified (ta
+ Td), the process proceeds to step 615, where the second
The electromagnetic valve 28 is closed by a control signal from the controller 41, whereby the first flow path opening / closing means 24 is closed, and a series of purification steps are completed and a steady operating state is achieved.

On the other hand, during the HC desorption / purification process (hence, t ≦ ta + td), since the recirculated exhaust gas is flowing through the adsorption device 22, a differential pressure is generated in the manometer 16. This differential pressure has a value proportional to the exhaust gas flow rate Q _td flowing in the adsorption device 22 as described above. Then, as shown in FIG. 11, when the leakage flow rate Q _d from the flow path opening / closing means 23 (FIG. 4) increases, the flow rate Q _td increases.

If actuator 231, shaft 2
If the 32 or the blade 230 is damaged,
_d becomes the allowable value Q _d0 or more, so the flow rate Q _td is as shown in FIG.
It becomes Q ₁ or more as shown in. Therefore, the return channel 35
The amount of HC that is returned from the tank decreases, and the overall purification capacity decreases.

Therefore, by monitoring the pressure difference in the adsorption device 22, it is possible to diagnose the malfunction of the device. That is, in step 633, if the passing flow rate Q _td in the desorption process is equal to or more than Q ₁ , step 61
After closing the second solenoid valve (flow path opening / closing means 24) in 4, the device failure information is output in step 606.

On the other hand, even if the actuator 231, the shaft 232, and the blade 230 are operating normally, if the reed valve 26 fails, the return passage 35 causes the catalyst device 21 to move.
The flow rate Q _r (Fig. 4) of the exhaust gas recirculated to is reduced. On the other hand, the exhaust gas flow rate Q _td flowing in the adsorption device 22 and the return flow rate Q _r are substantially equal to each other, and when Q _td becomes equal to or less than the allowable value Q ₂ shown in FIG. 12, the temperature rise of the adsorption device 22 is delayed. Then, set time ( _ta + _td ) for _removing and purifying HC
Even after passing, the problem that desorption / purification is not completed occurs.

Therefore, the failure of the reed valve 26 can also be judged by the passage flow rate Q _td being equal to or less than the set value Q ₂ . That is, in step 633, if the passing flow rate Q _td is equal to or less than Q ₂ , step 614,
Proceeding to 606, the information about the device failure is output.

In this embodiment, since the flow rate in the adsorption device 22 is measured, the leakage from the flow path opening / closing means 23 can be detected with high accuracy in both cases of adsorbing HC and desorbing / purifying it. Moreover, since the abnormality of the reed valve 26 can be detected, there is an advantage that the failure diagnosis is more accurate than that of the first embodiment. Others are the same as those in the first embodiment.

Embodiment 3 This embodiment is an embodiment of the third invention in which the failure diagnosis device 12 in Embodiment 1 is changed as shown in FIGS. 13 and 14. That is, as shown in FIG. 13, the failure diagnosis device 1 of this example
2 is H in the discharge flow path 34 by the HC sensor 17.
The C concentration is detected, and the failure of the exhaust emission control device 1 is diagnosed according to the flowchart of the failure diagnosis shown in FIG.

At step 601, when the engine 51 is started (= IG.ON), the routine proceeds to step 621. Then, in step 621, the controller 41 determines whether or not the adsorption of the adsorption device 22 is possible by receiving signals from an engine water temperature sensor and an exhaust temperature sensor (not shown). For example, when the value T _w (° C.) of the water temperature sensor is equal to or lower than the adsorbable temperature and T _wa (° C.), it is determined that the HC adsorbing process is being performed, the process proceeds to the next step 603, and the first solenoid valve 27 is opened. The exhaust gas flows through the adsorption device 22, and the cold HC in the exhaust gas is adsorbed.

While adsorbing the cold HC,
In step 641, the HC concentration C of the exhaust gas is detected by the HC sensor 17 and monitored by the failure diagnosis device 12. An example of this change in the density C is shown in FIG.
The HC concentration C is measured by the adsorption device 22 immediately after the engine 51 is started.
It becomes smaller due to the adsorption of No., and the value does not exceed the allowable value C _{a in the} normal case.

However, the leakage flow rate from the first flow path opening / closing means 23 is increased, the adsorption device 22 is damaged, etc.
If the exhaust gas leaks from the hole 224 shown in (4), the amount of cold HC adsorbed decreases and C exceeds the allowable value C _a . Therefore, in step 641,
Check the concentration C of the HC sensor 17, and check the above HC concentration C
Is smaller than the set value C _a .

If the HC concentration C is equal to or higher than C _a , the process proceeds to steps 605 and 606 as in the first and second embodiments, and device failure information is output. That is, when the flow path opening / closing means 23 becomes defective as described above, step 64
By monitoring the HC concentration C in No. 1, the device failure can be detected.

On the other hand, if the HC concentration is the normal value (C <C _a ) in step 641, the process proceeds to step 623, and in step 623, the time t after the start is checked, and within a predetermined time ta (t ≦ ta If it is), the routine for checking the HC concentration C (step 641) is continued through step 603. The predetermined time ta is the time for which HC adsorption should be continued as described above.

On the other hand, when a predetermined time (ta) elapses after the engine is started in step 623, step 6
10, the first electromagnetic valve 27 is closed by the signal from the controller 41, and the flow path opening / closing means 23 is switched to the position shown by the solid line in FIG. As a result, the exhaust gas has its HC purified by the catalyst device 21, which has already become hot and has been activated, and flows through the second main flow path 32.

Then, in step 612, the second flow path opening / closing means 24 is opened. As a result, the directional valve 25
HC which is intermittently opened and desorbed from the adsorption device 22
Enters the exhaust manifold 52 and is purified by the catalyst device 21 together with HC in the exhaust gas from the engine 51.

Then, in step 645, the HC concentration C in the HC desorption process is checked. As shown in FIG. 16, the HC concentration C in the HC desorption step shows an extremely small value under normal conditions. Therefore, if the HC concentration C is greater than or equal to the set value C _d , it is abnormal and step 61
4, 606, the second flow path opening / closing means 24 is closed to be in a steady state, and device failure information is output. The set value C _d is smaller than the set value C _a .

The causes of the HC concentration C exceeding the set value C _d include the increase of the leakage flow rate Q _d from the flow path opening / closing means 23, the leakage of the exhaust gas from the hole 224 (FIG. 2) due to the damage of the adsorption device 22, There is a problem such as leakage of HC from the upstream side of the adsorption device 22 to the second main flow path 32 due to blockage of the return flow path 35.

As described above, according to the failure diagnosis device 12 of the present embodiment, it is possible to detect a device failure due to a failure of the flow path opening / closing means 23, a failure of the adsorption device 22, a blockage of the return flow path 35, or the like. On the other hand, if the HC concentration continues to be normal in step 645 and the desorption process time (ta + td) has elapsed in step 646, the process proceeds to step 615, and the flow path opening / closing means 24 is opened as in the steady operation. The failure diagnosis routine is terminated without closing and outputting failure information (no failure).

Compared to the first embodiment, this embodiment directly measures the HC concentration behind the adsorption device 22, so that the HC leakage can be detected with high accuracy during both adsorption and desorption / purification. There is an advantage that the fault diagnosis is more accurate than that of the first embodiment. Others are the same as those in the first embodiment.

Embodiment 4 As shown in FIGS. 17 and 18, this embodiment is an embodiment of the fourth invention in which the failure diagnosis device 13 in Embodiment 1 is changed. That is, as shown in FIG. 17, the failure diagnosis device 13 of the present example is provided with the HC sensor 18 for detecting the HC concentration in the return flow path 35, and the exhaust gas purification device 1 fails according to the failure diagnosis flow shown in FIG. Make a self-judgment.

In FIG. 17, the HC sensor 18
Is disposed near the adsorption device 22 in the return flow passage 35, but may be disposed near the engine 51 in the return flow passage 35. When the engine 51 is started in step 601, signals from an engine water temperature sensor and an exhaust temperature sensor (not shown) are received, and the controller 41 causes the adsorption device 22 to operate.
Whether or not adsorption is possible is determined.

That is, in step 621, the value T _w
If (° C.) is equal to or lower than the adsorbable temperature T _wa (° C.), the first electromagnetic valve is opened in step 603, the exhaust gas flows through the adsorption device 22, and the cold HC in the exhaust gas is adsorbed.
Subsequently, when a predetermined time (ta) has elapsed after the engine was started in step 623, the first electromagnetic valve 27 is closed by a signal from the controller 41 in step 610, and the flow path opening / closing means 23 is indicated by the solid line in FIG. Switched to position.

As a result, the exhaust gas has its HC purified by the catalyst device 21 that has already become hot and activated, and flows through the second main flow path 32. After the engine 51 has warmed up and the first solenoid valve 27 has closed as described above, the controller 41 opens the solenoid valve 28 in step 612.

Then, as in the first embodiment, the flow path opening / closing means 24 is opened, the directional valve 25 is opened intermittently, and the HC desorbed from the adsorption device 22 flows into the exhaust manifold 52. Then, it is purified by the catalyst device 21 together with HC in the exhaust gas from the engine 51. And step 64
In step 6, after the time until HC is completely desorbed and purified [t> (ta + td)], in step 615, the second solenoid valve 28 is closed by a signal from the controller 41, which causes the flow. The road opening / closing means 24 is closed, and a series of purification work is completed.

While desorbing and purifying the HC, the exhaust gas to be recirculated flows through the return passage 35 in which the HC sensor 18 is provided. Then, HC is desorbed from the adsorption device 22. As shown in FIG. 19, the HC concentration C increases as the adsorption device 22 is heated with time during the beginning. Then, when all the adsorbed HC have been desorbed, the value becomes very small like the HC flowing in the second main flow path 32. If the device is normal, HC
Within the desorption / purification time [ta <t <(ta + t
In d)], the value obtained by multiplying the HC concentration C by the return flow rate Q _r and time integration, that is, the total reflux HC amount W becomes equal to or greater than the allowable value W ₀ (FIG. 20).

In the failure diagnosis device 13, a calculation program which can calculate the recirculation flow rate Q _r flowing through the return flow path 35 from the operating state of the engine 51 is set in advance (flow rate calculation means). Then, the integrating means calculates the total HC amount W from the above Q _r and C. And the flow path opening / closing means 2
If the amount of leaked gas from No. 3 increases or the exhaust gas leaks from the hole 224 in FIG. 2 due to damage to the adsorption device 22, the amount of HC that is recirculated decreases, and W is W ₀
Will not exceed.

Further, even if the reed valve 26 fails and HC is no longer recirculated, the amount of HC decreases, and the above W becomes W ₀
Will not exceed. Therefore, if the actuator 231, the shaft 232, the blade 230, the suction device 2
2. Further, when the reed valve 26 is damaged, in step 650, the malfunction of the device can be diagnosed by monitoring the refluxed HC concentration C as described above.

Then, in step 650, the reflux H
If the C amount is less than or equal to W ₀ , the process proceeds to step 606, and failure information is output. Others are the same as those in the first embodiment.

Embodiment 5 This is an embodiment of the fifth invention, and is another embodiment in which the failure diagnosis device 14 is modified in Embodiment 1 as shown in FIGS. 21 and 22. That is, as shown in FIG. 21, the failure diagnosis device 14 of the present example is provided with temperature sensors 190 and 191 respectively on the downstream side of the adsorption device 22 and the return flow path 35, whereby the adsorption device 22 and the return flow path 35 are connected. The temperatures Tri and Tre of the exhaust gas passing therethrough are measured, and the failure of the exhaust gas purification device 1 is diagnosed according to the flowchart shown in FIG.

First, when the start of the engine 51 is detected in step 601, the process proceeds to step 652. In step 652, the signal from the temperature sensor 190 is received,
The value of the temperature Tri is checked to determine whether or not the adsorption device 22 has an adsorption ability. That is, in step 652, the value of the temperature Tri is equal to the temperature Tri that the adsorption device can adsorb.
If it is a or less, in step 603, the first electromagnetic valve 27 is opened, the flow path opening / closing means 23 is switched to the position of the broken line in FIG. 21, the exhaust gas flows through the adsorption device, and the cold in the exhaust gas is reached. HC is adsorbed.

Next, while the cold HC is being adsorbed as described above, in step 654, the magnitude of the leak flow rate Qa of the exhaust gas from the flow path opening / closing means 23 is judged.
The determination of the leak flow rate Qa is performed in step 604 of the first embodiment.
Similarly to the above, it is performed depending on the magnitude of the temperature rising rate. However, in the first embodiment, the determination is made using the temperature rising rate Vt of the adsorption device 22, but in the present example, the temperature rising rate Vt ′ of the temperature of the exhaust gas flowing downstream of the adsorption device 22 is used. judge. The temperature increase rate Vt ′ is set to a predetermined time (4 to 5) after closing the flow path opening / closing means 23 in step 603.
After waiting for 2 seconds), it is measured and used for judgment.

As a result, the temperature rising rate Vt 'is equal to the allowable value Vto'.
If it is smaller than the above, it is determined that the flow path opening / closing means 23 has a failure, that is, the exhaust gas purifying apparatus 1 has a failure, the first electromagnetic valve 27 is closed in step 605, and the failure information is output in step 606. On the other hand, in step 652 above,
When the temperature Tri exceeds the adsorbable temperature Tria due to engine warm-up, the routine proceeds to step 610, where the first electromagnetic valve 27 is closed, and the flow path opening / closing means 23 is set to the position shown in FIG.
1 is switched to the position indicated by the solid line. Then, the exhaust gas becomes H in the catalytic device 21 which has already become hot and has been activated.
After C is removed and purified, it flows through the second main flow path 32.

Then, in the subsequent steps 656 to 659, the following operation is continued until the temperature Tri becomes a value exceeding the temperature Trid at the end of desorption purification from the adsorption device 22. That is, immediately after the first solenoid valve 27 is closed, the value of the temperature sensor 190 is read and this value Tri is monitored,
If the temperature Tri is equal to or lower than the temperature Trid at the end of purification in step 656, the process proceeds to step 612 and the second solenoid valve 28 is opened. Then, as in the case of the first embodiment, the flow path opening / closing means 23 is opened, the directional valve 25 is opened intermittently, and the HC desorbed from the adsorption device 22 flows into the exhaust manifold 52 and the engine 51. H in the exhaust gas from
Purified in the catalyst device 21 together with C.

At this time, in the following step 657, the magnitude of the leakage flow rate Qd from the flow path opening / closing means 23 is determined.
This determination is also made in the same manner as in the first embodiment, the heating rate Vtd '.
(However, the temperature of the exhaust gas downstream of the adsorption device 22). Here, if the temperature increase rate Vtd 'is larger than the allowable value Vt1', it is determined that the flow path opening / closing means 23 (exhaust gas purification device 1) has failed, and in step 614, the second electromagnetic valve 2
8 is closed, and failure information is output in step 606.

On the other hand, if it is determined in step 657 that the temperature increase rate Vtd 'is less than or equal to the allowable value Vt1' and the flow path opening / closing means 23 is normal, the process proceeds to step 658. Then, the temperature Tre of the exhaust gas flowing through the return passage 35 is measured by the temperature sensor 191 and the temperature Tri is measured by the temperature sensor 190 at the same time.

The microcomputer 40 incorporates means (program) for calculating the correlation coefficient D between the temperature Tri and the temperature Tre. That is, the correlation coefficient D is obtained as follows by collecting n values of temperature Tri and temperature Tre at every sampling time ts and calculating the average value, standard deviation K, and covariance C thereof. D = C (Tri, Tre) / {K (Tri) * K (Tre)} where C (Tri, Tre) = [Σ {Tri (i) -Tri (av)}
* {Tre (i) -Tre (av)}] / n {K (Tri)} ² = [Σ {Tri (i) -Tri (av)}
² ] / n {K (Tre)} ² = [Σ {Tre (i) -Tre (av)}
² ] / n, and Tri (i) = i-th data of Tri Tre (i) = i-th data of Tre Tri (av) = average value of n Tris Tre (av) = n Tres Is the average value of. Then, more specifically, the sampling time ts in this example is 0.5 seconds, and n is 100.

If the directional valve 25 fails, the second opening / closing means 24 does not open, or if the reed valve 26 deteriorates in sealing performance and a back flow of exhaust gas occurs, the gas is recirculated. The exhaust gas flow rate Qr is reduced (FIG. 4). When the second opening / closing means 24 cannot open the valve,
Since the flow rate Qr of the recirculated exhaust gas becomes zero, even if the temperature Tri corresponding to the temperature of the inlet portion of the recirculated exhaust gas is affected by the temperature of the exhaust gas flowing through the second main flow path 32 and fluctuates,
Since there is no flow of exhaust gas in the return passage 35, the temperature Tre in the middle of the return passage 35 does not change (or is extremely small). Therefore, the correlation between the temperature Tri and the temperature Tre becomes very small, and the correlation coefficient D does not exceed the set value.

Therefore, as shown in step 659,
The failure of the second solenoid valve 24 can be determined by the magnitude of the correlation coefficient. If it is determined that a failure occurs, the process proceeds to step 614, the second solenoid valve 28 is closed, and failure information is output at step 606. Also, the directional valve 26
When the sealing performance of No. 2 deteriorates and causes backflow of the exhaust gas, the flow rate Qr of the recirculated exhaust gas decreases. And
Exhaust gas flows back from the exhaust manifold 52 to the adsorption device 22 through the return flow path 35. Therefore, the temperature Tre, which corresponds to the temperature in the middle of the return flow path 35, is affected not only by the temperature variation at the inlet of the recirculated exhaust gas but also by the above-mentioned backflow exhaust gas. Since the temperature fluctuation of the backflow exhaust gas is not synchronized with the temperature fluctuation of the exhaust gas flowing in the second main flow path 32, the temperature Tre corresponding to the midway temperature in the return flow path 35 is equal to the temperature Tri. The correlation becomes very small, and the correlation coefficient D does not exceed the set value.

Therefore, in step 659, the failure of the reed valve 26 can be determined by the magnitude of the correlation coefficient. Then, when it is determined that there is a failure, the second solenoid valve 28 is closed in step 614, and step 60
At 6, the failure information is output.

After the flow path opening / closing means 23 is switched to the open position shown by the solid line in the figure to enter the HC desorption step,
When the route of steps 612 to 659 is normally followed, in step 656, the temperature Trid at which the desorption purification of HC is completed is eventually reached, and the process proceeds to step 615.
Then, the second electromagnetic valve 28 and the flow path opening / closing means 24 are closed to enter a normal operating state. As mentioned above, according to this example,
It is possible to provide the exhaust gas purification device 1 having a self-diagnosis function of the device and having excellent exhaust gas purification characteristics.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an exhaust emission control device according to a first embodiment.

FIG. 2 is an exploded perspective view of the adsorption device according to the first embodiment.

FIG. 3 is a flowchart of control and failure diagnosis of the exhaust emission control device of the first embodiment.

FIG. 4 is a flow of exhaust gas around an adsorption device in the exhaust emission control device of the first embodiment.

FIG. 5 is a graph showing the relationship between the temperature rise rate and the leakage flow rate Q _a in the adsorption process of the exhaust gas purification device of the first embodiment.

FIG. 6 is a graph showing the relationship between the temperature rising rate and the leakage flow rate Q _d in the desorption process of Example 1.

FIG. 7 is a graph _showing the relationship between the temperature rising rate and the return flow rate Q _r in the desorption process of Example 1.

FIG. 8 is a system configuration diagram of an exhaust emission control device according to a second embodiment.

FIG. 9 is a flowchart of control and failure diagnosis of the exhaust emission control device of the second embodiment.

FIG. 10 is a graph showing the relationship between the flow rate passing through the adsorption device and the leakage flow rate Q _a in the adsorption process of Example 2.

FIG. 11 is a graph showing the relationship between the passing flow rate and the leak flow rate Q _d of the adsorption device in the desorption process of Example 2.

FIG. 12 is a graph _showing the relationship between the passing flow rate and the returning flow rate Q _r of the adsorption device in the desorption process of Example 2.

FIG. 13 is a system configuration diagram of an exhaust emission control device according to a third embodiment.

FIG. 14 is a flowchart of control and failure diagnosis of the exhaust emission control device of the third embodiment.

FIG. 15 is a transition graph of HC concentration in the adsorption process of Example 3.

16 is a transition graph of HC concentration in the desorption process of Example 3. FIG.

FIG. 17 is a system configuration diagram of an exhaust emission control device according to a fourth embodiment.

FIG. 18 is a flowchart of control and failure diagnosis of the exhaust emission control device of the fourth embodiment.

FIG. 19 is a transition graph of HC concentration in the desorption process of Example 4.

FIG. 20 is a transition graph of the integrated value of the amount of refluxed HC in the desorption process of Example 4.

FIG. 21 is a system configuration diagram of an exhaust emission control device according to a fifth embodiment.

FIG. 22 is a flowchart of control and failure diagnosis of the exhaust emission control device of the fifth embodiment.

FIG. 23 is a diagram showing a relationship between a downstream exhaust gas temperature Tri of the adsorption device and an exhaust gas temperature Tre in the return passage in a normal state in the exhaust emission control device of the fifth embodiment.

FIG. 24 is a diagram showing the relationship between the exhaust gas temperature Tri of the downstream side of the adsorption device and the exhaust gas temperature Tre in the return passage at the time of failure in the exhaust emission control device of the fifth embodiment.

FIG. 25 is a diagram showing changes in the correlation coefficient D between the temperature Tri and the temperature Tre during normal operation and during failure in the exhaust emission control device according to the fifth embodiment.

[Explanation of symbols]

 1. ． ． Exhaust gas purification device, 10. ． ． Failure diagnosis device, 21. ． ． Catalyst device, 22. ． ． Adsorption device, 23, 24. ． ． Flow path opening / closing means, 31. ． ． First main flow path, 32. ． ． Second main flow path, 33. ． ． Adsorption channel, 35. ． ． Return channel,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G01M 15/00 Z (72) Inventor Hiroyuki Usami 1-1, Showa-cho, Kariya city, Aichi prefecture Nidec Co., Ltd. (72) Inventor Kinji Hohei 1-1, Showa-cho, Kariya city, Aichi prefecture Nihondenso Co., Ltd.

Claims (10)

[Claims] 1. An exhaust purification device provided in an exhaust passage of an engine, wherein the exhaust purification device comprises a catalyst device located upstream of the exhaust passage for purifying exhaust gas.
A main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful gas, and a flow path located downstream of the first main flow path and parallel to the adsorption flow path. A second main channel forming a channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a channel branched from the adsorption channel to reach the upstream side of the catalyst device. Return flow path, flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a failure diagnostic device for self-diagnosing malfunctions of the device. The return flow passage is provided with a directional valve that allows only the flow of exhaust gas from the adsorption flow passage to the upstream side of the catalyst device. Operating the flow path opening / closing means to the first operating state,
As a result, the return flow path is closed, the exhaust gas that has passed through the adsorption flow path is circulated to the exhaust flow path, and the flow of exhaust gas from the second main flow path to the exhaust flow path is blocked.
When the temperature of the exhaust gas is high, the flow path opening / closing means is operated to the second operation state, whereby the exhaust gas is circulated from the second main flow path to the discharge flow path and the return flow path is opened to cause the adsorption flow. The exhaust gas that has passed through the passage is circulated to the return flow passage, and the flow of the exhaust gas from the adsorption flow passage to the discharge flow passage is blocked, and the failure diagnosis device measures the temperature of the adsorption device, and the first operating state. When the temperature rise rate is equal to or lower than a set value, it is determined that the device has failed. In the second operation state, when the temperature rise rate is equal to or higher than a predetermined upper limit value or equal to or lower than a predetermined lower limit value, An exhaust emission control device having a determination means for determining a failure. 2. An exhaust purification device provided in an exhaust passage of an engine, wherein the exhaust purification device comprises a catalyst device located upstream of the exhaust passage for purifying exhaust gas.
A main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and a flow path located downstream of the first main flow path in parallel with the adsorption flow path. A second main channel forming a channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a channel branched from the adsorption channel to reach the upstream side of the catalyst device. Return flow path, flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a failure diagnostic device for self-diagnosing malfunctions of the device. The return flow passage is provided with a directional valve that allows only the flow of exhaust gas from the adsorption flow passage to the upstream side of the catalyst device. Operating the flow path opening / closing means to the first operating state,
As a result, the return flow path is closed and the exhaust gas that has passed through the adsorption flow path is circulated to the exhaust flow path, and the flow of exhaust gas from the second main flow path to the exhaust flow path is blocked, while the exhaust gas temperature is high. In the above, the flow passage opening / closing means is operated to the second operation state, whereby exhaust gas is circulated from the second main flow passage to the discharge flow passage, and the return flow passage is opened to pass through the adsorption flow passage. Exhaust gas is circulated to the return flow path, and the flow of exhaust gas from the adsorption flow path to the exhaust flow path is cut off, and the failure diagnosis device measures the flow rate of exhaust gas passing through the adsorption device, and the first operating state. When the passing flow rate is below a set value, it is determined that the device is faulty. With a judgment means to judge Exhaust purifying apparatus according to claim Rukoto. 3. An exhaust gas purification device provided in an exhaust passage of an engine, the exhaust gas purification device comprising a catalyst device located upstream of the exhaust passage for purifying exhaust gas.
A main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and a flow path located downstream of the main flow path and parallel to the adsorption flow path. A second main flow path to be formed, a discharge flow path located downstream of the adsorption flow path and the second main flow path, and a return path that branches from the adsorption flow path to reach the upstream side of the catalyst device. A flow path, a flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path, and a return flow path, a controller for controlling the flow path opening / closing means, and a failure diagnostic device for self-diagnosing a malfunction of the device. The return flow passage is provided with a directional valve that allows only the flow of exhaust gas from the adsorption flow passage to the upstream side of the catalyst device. The road opening / closing means is operated to the first operating state, whereby the return The exhaust passage that closes the passage and flows through the adsorption passage is circulated to the exhaust passage, and the flow of the exhaust from the second main passage to the exhaust passage is blocked, while the exhaust gas flows at high temperature. The passage opening / closing means is operated to the second operation state, whereby the exhaust gas is circulated from the second main flow passage to the exhaust flow passage, and the return flow passage is opened to return the exhaust gas passing through the adsorption flow passage. The exhaust flow from the adsorption flow path to the exhaust flow path, and the failure diagnosis device measures the concentration of a predetermined exhaust gas in the exhaust flow path, and the exhaust gas concentration is An exhaust emission control device, comprising: a determination unit that determines a device failure when a value that is equal to or greater than a set value that is set to a different value between the first operating state and the second operating state. 4. An exhaust purification device provided in an exhaust passage of an engine, wherein the exhaust purification device comprises a catalyst device located upstream of the exhaust passage for purifying exhaust gas.
A main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful substances, and a flow path located downstream of the first main flow path in parallel with the adsorption flow path. A second main channel forming a channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a channel branched from the adsorption channel to reach the upstream side of the catalyst device. Return flow path, flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a failure diagnostic device for self-diagnosing malfunctions of the device. The return flow passage is provided with a directional valve that allows only the flow of exhaust gas from the adsorption flow passage to the upstream side of the catalyst device. Operating the flow path opening / closing means to the first operating state,
As a result, the return flow path is closed, the exhaust gas that has passed through the adsorption flow path is circulated to the exhaust flow path, and the exhaust flow from the second main flow path to the exhaust flow path is shut off. The flow passage opening / closing means is operated, while at the time of high temperature of the exhaust gas, the flow passage opening / closing means is operated to the second operation state, whereby the exhaust gas is circulated from the second main flow passage to the exhaust flow passage and the return is performed. The flow path is opened, the exhaust gas that has passed through the adsorption flow path is circulated to the return flow path, and the flow of exhaust gas from the adsorption flow path to the exhaust path is blocked. Return flow rate calculating means for calculating the exhaust flow rate of the return flow path, and integrating means for measuring the concentration of the exhaust gas in the return flow path and integrating the total amount of the exhaust gas passing through the return flow path in the second operating state. And the above exhaust gas Exhaust gas purification apparatus, characterized in that a determining means and device failure if the accumulated amount is equal to or less than the set value. 5. The failure diagnosis device according to claim 3 or 4, further measuring the temperature of the adsorption device, and whether or not the temperature rising rate is equal to or higher than a set value in the first operating state, And an exhaust emission control device having second determination means for determining whether or not the rising speed is equal to or higher than a predetermined upper limit value or lower than a predetermined lower limit value in the second operating state. 6. The failure diagnosis device according to claim 3 or 4, further measuring the flow rate of the exhaust gas passing through the adsorption device, and determining whether the flow rate is equal to or less than a set value in the first operating state. And an exhaust gas purification device comprising third determination means for determining whether or not the passage flow rate is equal to or more than a predetermined upper limit value or less than a predetermined lower limit value in the second operation state. 7. An exhaust gas purification device provided in an exhaust passage of an engine, the exhaust gas purification device comprising a catalyst device located upstream of the exhaust passage for purifying exhaust gas.
A main flow path, an adsorption flow path located downstream of the first main flow path and having an adsorption device for adsorbing harmful gas, and a flow path located downstream of the first main flow path and parallel to the adsorption flow path. A second main channel forming a channel, an exhaust channel located downstream of the adsorption channel and the second main channel, and a channel branched from the adsorption channel to reach the upstream side of the catalyst device. Return flow path, flow path opening / closing means for opening / closing the adsorption flow path, the second main flow path and the return flow path, a controller for controlling the flow path opening / closing means, and a failure diagnostic device for self-diagnosing malfunctions of the device. The return flow passage is provided with a directional valve that allows only the flow of exhaust gas from the adsorption flow passage to the upstream side of the catalyst device. Operating the flow path opening / closing means to the first operating state,
As a result, the return flow path is closed, the exhaust gas that has passed through the adsorption flow path is circulated to the exhaust flow path, and the flow of exhaust gas from the second main flow path to the exhaust flow path is blocked.
When the temperature of the exhaust gas is high, the flow path opening / closing means is operated to the second operation state, whereby the exhaust gas is circulated from the second main flow path to the discharge flow path and the return flow path is opened to cause the adsorption flow. The exhaust gas that has passed through the passage is circulated to the return flow passage, and the flow of the exhaust gas from the adsorption flow passage to the discharge flow passage is cut off. The failure diagnosis device includes the downstream side of the adsorption device and the return flow passage. Exhaust temperature is measured, the degree of correlation between the two exhaust temperatures is calculated in the second operating state, and if the degree of this correlation does not reach a certain level, it is determined that the device is faulty. An exhaust emission control device comprising: 8. The apparatus according to claim 7, wherein the determination means calculates the degree of correlation between the two exhaust temperatures, and when the degree of the correlation does not reach a certain level, it means that the device has failed. An exhaust emission control device, characterized in that the determination time is in the second operation state and the engine is in an idling state. 9. The apparatus according to claim 7, wherein the determination means calculates the degree of correlation between the two exhaust temperatures, and if the degree of the correlation does not reach a certain level, it means that the device has failed. An exhaust emission control device, characterized in that the determination time is in the second operation state and the vehicle is in a deceleration state. 10. The fault diagnosis device according to claim 7, further comprising measuring the temperature of the adsorption device, and the rate of temperature rise is equal to or higher than a set value in the first operating state. Whether or not, and this rising speed is the second
An exhaust emission control device having a fourth determination means for determining whether or not the value is equal to or more than a set value in an operating state.