JP2008190463A - Soot removing device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soot removing device for a diesel engine which can reduce soot without performing any forced regeneration of a particulate filter in the area where self-regeneration of a DPF is difficult. <P>SOLUTION: The soot removing device for the diesel engine 20 has either an oxidation catalyst 32 or the particulate filter 1, or both of them inside, and is provided with a detection means, a control means 4, and a by-pass means. The detection means detects the operating condition of the engine 5, and the control means 4 controls the soot removing device based on the operating condition. The by-pass means makes the exhaust gas 10 bypass the particulate filter 1 when the operating condition of the engine deviates from the self-regeneration area of the particulate filter 1 and from a zone-control area of emission control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technology for a black smoke purification device for a diesel engine that reduces emission of black smoke.

  In recent years, environmental concerns and health effects are concerned, so black smoke (PM) and PM (Particulate Matter) in exhaust gas discharged from diesel engines such as automobiles, ships, and generators. Development of a device that removes water is in progress. In some areas, regulations are being reinforced more specifically, and it is urgently necessary to deal with them. As technical methods for dealing with these, there are a method for preventing black smoke emission by measures such as fuel injection timing and mixing ratio on the engine side, and a method for dealing with exhaust system post-treatment. As a method for dealing with exhaust system after-treatment, for example, a technology for attaching a black smoke removal device (DPF: Diesel Particulate Filter) to an exhaust device such as a diesel engine is already known, and a commercially available retrofit type black As a smoke removing device, a ceramic filter system in which a ceramic is formed into a honeycomb shape is the mainstream. Various methods for regenerating the clogging of black smoke have been studied for these devices, but they are not yet technically sufficient.

  As a conventional technique, Patent Document 1 proposes a method of forcibly regenerating in a non-reproducible region of DPF. Specifically, when the exhaust temperature is low and less than 250 ° C., it is difficult to raise the temperature of the catalyst, and in the region where DPF regeneration is not performed with priority on fuel consumption (non-renewable region), By combining the aperture, heat dissipation to the exhaust is suppressed and the temperature of the DPF is easily increased. By performing this and post-injection, the temperature of the DPF is raised and the regeneration is possible.

Patent Document 2 proposes a method in which when it is determined that filter regeneration is necessary, the load on the engine is increased, and as a result, the exhaust gas temperature rises and the exhaust gas purification filter is regenerated. Yes.
JP 2006-132458 A JP 2005-337062 A

  In industrial institutions, they are used in various ways depending on the application and operator. Diesel particulate filters have a region where self-regeneration is difficult. The definition of the self-regeneration region here refers to an operation region in which the amount of soot entering the particulate filter is lower than the amount of soot oxidized on the particulate filter. This state is a region where the soot amount accumulated at the balance point is well below the differential pressure and the limit reference value of the pooled soot, although it varies depending on other factors such as the pooled state of soot and the outside temperature.

In general, it is said that the oxidation reaction by oxygen is dominant on the particulate filter in the exhaust gas temperature range of 450 ° C. or higher. This oxidation rate is greatly influenced by temperature. Oxidation by oxygen is considered to be slow and slow to accumulate soot unless there is a temperature of 600 ° C. or higher. If the amount of oxygen suddenly becomes sufficient from a state where the temperature is 600 ° C. or more with a large amount of soot accumulated, for example, when idling is suddenly dropped, the oxidation rapidly proceeds to a temperature exceeding 1000 ° C. and the filter melts down. Oxygen oxidation is difficult to control because it causes so-called runaway regeneration. When the exhaust gas temperature is in the range of 250 ° C. to 350 ° C., NO 2 is generated on the preceding oxidation catalyst or particulate filter, and this NO 2 returns to NO and oxidizes soot on the catalyst on the particulate filter. This oxidation is governed not only by the temperature but also by the amount of NO 2, that is, the amount of the oxidation catalyst and the amount of catalyst on the particulate filter. There is no runaway for this. When the exhaust gas temperature is 250 ° C. or lower, self-regeneration is difficult. In a region where self-regeneration is difficult, it is necessary to perform so-called forced regeneration in which the exhaust gas temperature is forcibly increased.
The present invention has been made in view of the above circumstances, and its purpose is to reduce black smoke without forced regeneration of the particulate filter in an area where DPF self-regeneration is difficult. An object of the present invention is to provide a black smoke purification device for a diesel engine.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
Assuming an exhaust gas treatment device using a certain particulate filter, in a region where the exhaust temperature is high, the self-renewable region is determined by the exhaust gas temperature and the soot discharge amount. In the region where the temperature is relatively low, the reproducible region is determined by the exhaust gas temperature, the NOx amount, and the soot discharge amount. FIG. 1 shows an example in which a self-recoverable region is examined by plotting Sd, exhaust gas temperature, and NOx amount, which are representative characteristics of the soot amount, on a rotation-torque diagram of an industrial engine.
It goes without saying that the area can be changed to some extent by changing the size of the particulate filter and the catalyst amount density or by matching the engine.

Next, the exhaust gas regulation zone will be described. In recent general-purpose engine exhaust gas regulations, there are many examples in which transient regulations and zone regulations are provided in addition to mode regulations. An example of the NTE zone, which is the zone regulation in the next EPA regulation, is shown (see FIG. 2). Within the shaded range shown in FIG. 2, it is determined that it does not exceed 1.25 times the mode regulation value. Each symbol indicates the following value.
1) Region larger than the speed calculated by the following formula: Nlo + 0.15 × (Nhi−Nlo) (circled number 1)
Nhi: Maximum rotation speed at which the 70% iso-output line of the maximum output intersects with the torque curve Nlo: Minimum rotation speed at which the 50% iso-output line of the maximum output intersects with the torque curve 2) Area of 30% or more of the maximum torque (circle) Number 2)
3) Regardless of 1) and 2) above, the range within minimum fuel consumption + 5% (circled number 3)
4) Further, the area below the 30% equal output line of the maximum output is omitted regardless of 1), 2) and 3) above (circled number 4).
Further, FIG. 3 shows a superimposition of the reproducible area and the NTE zone. It is possible to make the self-reproducing area larger than the NTE zone. Further, as shown in FIG. 1, generally, soot is discharged at a low load because the amount of air is larger than that of fuel, and NOx is also low when the exhaust gas temperature is low in EGR.

Therefore, in the present invention, a bypass is provided in the particulate filter so that the filter is bypassed in the non-self regeneration region. An example is shown in FIG. Further, the bypass is closed during transient operation, start-up operation, and acceleration operation. As a result, the engine can always be operated in the self-regeneration area except during some transient operation. The bypass control valve may be a one-way valve. When the bypass control valve is opened, most of the exhaust gas is bypassed due to the ventilation resistance. In this plan, the bypass valve is opened and closed by a hydraulic cylinder. FIG. 5 shows an example in which the bypass is opened and closed by a bimetal valve that senses temperature without using a control means. Similarly, FIGS. 5 and 6 show examples of the outer periphery bypass route. FIG. 6 shows an example in which a DOC (oxidation catalyst) and a DPF are provided using an electrically driven control valve, and exhaust gas is bypassed after the DOC.
In addition, it is included in the technique of the present invention to provide an oxidation catalyst in order to reduce the non-renewable region, to use CSF which is an example of a continuous regeneration type DPF, or to provide an exhaust heating device for bypassing. Of course.

  That is, in claim 1, in a black smoke purification apparatus for a diesel engine having either one or both of an oxidation catalyst and a particulate filter, detection means for detecting an operating state of the engine, and based on the operating state Control means that controls the black smoke purification device, and bypass that exhaust gas bypasses the particulate filter when the engine operating state is outside the self-regeneration area of the particulate filter and outside the zone restriction area of the exhaust gas restriction Means.

  According to a second aspect of the present invention, when the control means determines that the engine operating state is the transient operation state, the start mode or the acceleration mode, the bypass means does not bypass the exhaust gas.

  According to a third aspect of the present invention, the bypass means includes a bypass passage and a bypass passage on / off valve, and the control means is electrically or hydraulically driven or pneumatically driven to open and close the bypass passage on / off valve. is there.

  According to a fourth aspect of the present invention, the bypass passage on-off valve is opened and closed by detecting the exhaust gas temperature.

  According to a fifth aspect of the present invention, the bypass passage opening / closing valve is a self-contained temperature sensitive valve.

  According to a sixth aspect of the present invention, the temperature sensitive member of the temperature sensitive valve is made of wax pellets, shape memory alloy or bimetal.

  According to a seventh aspect of the present invention, the bypass passage is formed in the outer peripheral portion of the particulate filter.

  According to an eighth aspect of the present invention, in the black smoke purification apparatus for a diesel engine in which the oxidation catalyst is disposed in the front stage and the particulate filter is disposed in the rear stage, the bypass passage bypasses the exhaust gas after the oxidation catalyst.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, the self-renewable region has a low load and a small fuel injection amount. In general, both PM and NOx have a low emission amount, and it is possible to enter the mode regulation without using a filter in this region. Therefore, when the particulate filter is in a region where self-regeneration is not possible, it is possible to operate by bypassing the filter. This eliminates the need for forced regeneration when the exhaust gas is at a low temperature. In addition, when using a particulate filter, it is always possible to operate in an area where self-regeneration is possible.

  According to claim 2, PM emission can be reduced by passing exhaust gas through a particulate filter without using a bypass during acceleration, start-up, or transient state during which PM is easily generated.

  According to the third aspect of the present invention, reliable opening / closing control of the bypass passage can be performed according to the engine operating condition.

  According to the fourth aspect of the present invention, whether or not the filter can be regenerated depends greatly on the exhaust gas temperature, so that the opening and closing of the bypass can be controlled by the exhaust gas temperature. Further, since the exhaust gas temperature range to be opened and closed can be set to be outside the zone regulation, the zone regulation can be dealt with.

  According to the fifth aspect of the present invention, the bypass can be opened and closed according to the exhaust gas temperature condition without using a control means, a temperature sensor, or the like.

  According to the sixth aspect of the present invention, the bypass can be opened and closed according to the exhaust gas temperature condition without using a control means, a temperature sensor, or the like.

  According to the seventh aspect of the present invention, when the exhaust gas flows through the bypass, the filter is prevented from being cooled because the exhaust gas flows around the particulate filter, and the filter itself can be brought close to the gas temperature. When the bypass is closed Can be less susceptible to thermal shock.

  According to an eighth aspect of the present invention, the non-renewable region of the particulate filter has a low exhaust gas temperature and a relatively large amount of HC components. In this region, it is difficult to activate the oxidation catalyst, but at least the HC component can be removed by passing the oxidation catalyst 32, and PM can be reduced.

Next, embodiments of the invention will be described.
4 is a schematic diagram showing a black smoke purification device for a diesel engine according to the present invention, FIG. 5 is a schematic diagram showing a black smoke purification device for a diesel engine in Example 2, and FIG. 6 is a black smoke for diesel engine in Example 3. FIG. 7 is a schematic diagram showing the purification device, FIG. 7 is a diagram showing a control flow for opening and closing the bypass passage, FIG. 8 is a block diagram showing the control means, and FIG. 9 is a diagram showing a control flow with hysteresis for opening and closing the bypass passage.

The whole structure of the black smoke purification apparatus for diesel engines which concerns on this invention using FIG. 4 is demonstrated.
As shown in FIG. 4, the diesel engine 5 (hereinafter referred to as the engine) is provided with an intake manifold 5a on one side of the engine body and an exhaust manifold 5b on the other side. A diesel engine black smoke purification device 20 (hereinafter referred to as a black smoke purification device) is connected to the exhaust manifold 5b through an exhaust pipe 9.
As shown in FIG. 4, the black smoke purification device 20 includes an inlet portion 2, a particulate filter 1, an outlet portion 3, and bypass means. The inlet portion 2 and the outlet portion 3 are formed in the housings 7a and 7b, respectively. The particulate filter 1 is disposed in the installation portion 1a between the housings 7a and 7b. The particulate filter 1 is kept airtight with both the housings 7a and 7b and the gasket 15, and is integrated with the V-shaped band 12. It is fixed to. A heat insulating sound absorbing material 8 is disposed in the inlet portion 2, and the heat insulating sound absorbing material 8 is pressed against the inner wall of the inlet portion 2 by heat insulating sound absorbing material pressing plates 13 and 16.
The bypass means includes a bypass pipe 6 serving as a bypass passage for bypassing the particulate filter 1 and a bypass control valve 11 serving as a bypass passage opening / closing valve capable of opening and closing the bypass passage.
The particulate filter 1 can be attached to and detached from the installation portion 1a.

The inlet pipe 2 is provided with the bypass pipe 6 for bypassing the exhaust gas 10 introduced through the exhaust pipe 9. The bypass pipe 6 is substantially U-shaped in a plan view, and the bypass pipe front part 6a is inserted through the inlet part 2 in a substantially vertical direction, is bent at a substantially right angle, and extends rearward. The bypass pipe 6 extending rearward is bent at a substantially right angle in the middle, and forms a bypass pipe middle part 6b between the bent parts. One side of the housing 7b is inserted from the rear bent portion through the bypass control valve 11 to form the bypass pipe rear part 6c, and the bypass pipe rear part 6c is connected to the outlet pipe 14 disposed in the outlet part 3. is doing. A large number of small holes 6d are provided in the cylindrical side wall of the bypass pipe front portion 6a through which the inlet pipe 2 is inserted. When the bypass control valve 11 is closed, the exhaust gas 10 enters the inlet portion 2 from the bypass pipe front portion 6a through the small hole 6d. The outlet portion 3 is provided with an outlet pipe 14 that discharges the exhaust gas 10 and a resonance pipe 25 that is parallel to the outlet pipe 14 and that reduces noise during exhaust gas discharge.
The bypass control valve 11 includes a butterfly valve 11a and an arm 17 having one end fixed below the rotation shaft of the butterfly valve 11a. The other end of the arm 17 is connected to a hydraulic cylinder 18 which is an example of an actuator, and the hydraulic cylinder 18 is connected to the controller 4 which is a control means. The butterfly valve 11a is rotated by driving the hydraulic cylinder 18 so that the flow passage area of the bypass pipe rear portion 6c can be changed. That is, when the bypass control valve 11 is closed, the bypass pipe 6 introduces the exhaust gas 10 to the inlet portion 2 through the small hole 6d, and then passes through the particulate filter 1 to the outlet pipe 14. Enters and exits from the outlet tube 14. On the other hand, when the bypass control valve 11 is open, the exhaust gas 10 hardly enters the small hole 6d due to ventilation resistance, and mainly passes through the bypass pipe 6 to the outlet pipe 14 in the outlet portion 2. It is introduced and discharged from the outlet pipe 14. Thus, the controller 4 controls the opening and closing of the bypass control valve 11 so that the exhaust gas 10 bypasses the particulate filter 1.
The controller 4 includes a central processing unit (CPU), a storage device (RAM or ROM), an interface, and the like, and a map for determining whether or not a self-regenerating area of the particulate filter 1 described later is stored in the storage device. Yes.
As shown in FIG. 8, the controller 4 is connected to a hydraulic cylinder 18, an exhaust gas temperature sensor 19, an engine speed sensor 21, a differential pressure sensor 33, and a position sensor 24 serving as a throttle position detecting means. .
In the present embodiment, only the particulate filter 1 is arranged inside the black smoke purification device 20, but as described later, a combination of an oxidation catalyst and a particulate filter, or only the oxidation catalyst is used as a black smoke purification device. It does not matter even if it is arranged inside.
In the present embodiment, the bypass control valve 11 is opened and closed by a hydraulic drive system that drives the hydraulic cylinder 18 based on an instruction from the controller 4. However, the present invention is not limited to this, and other drive systems are described later. Alternatively, a pneumatic driving method may be used.
Further, the valve mechanism of the bypass control valve 11 is not particularly limited to the butterfly valve, and various types such as a shutter valve can be applied.

Next, means for detecting the operating state of the engine will be described.
An exhaust gas temperature sensor 19 is attached to the exhaust pipe 9 as an operating state detection means, and the exhaust gas temperature is detected by the sensor 19.
Further, an engine speed sensor 21 as an operating state detecting means is attached to the crankshaft or flywheel of the engine 5 or a shaft linked to the crankshaft. The exhaust gas temperature sensor 19 and the engine speed sensor 21 are each connected to the controller 4.

  Further, the black smoke purification device 20 is provided with a differential pressure sensor 33 for measuring the differential pressure across the particulate filter 1. The differential pressure sensor 33 is connected to the controller 4. A differential pressure before and after the particulate filter 1 is detected by the differential pressure sensor 33 and sent to the controller 4.

  Further, as shown in FIG. 4, the adjustment of the driving force (the number of revolutions) of the engine 5 is performed by operating the operation lever 23 disposed in the driving operation unit or the like. The operation lever 23 is provided with a position sensor 24 for detecting the lever position of the operation lever 23, and this position sensor 24 is connected to the controller 4.

  When the operation lever 23 is operated, the lever position of the operation lever 23 is detected by the position sensor 24, and a signal corresponding to the lever position is input to the controller 4. Then, the controller 4 operates a throttle actuator (not shown) based on the input signal. The throttle actuator is connected to the engine 5, and the throttle position (throttle opening) is changed by the operation of the throttle actuator. The fuel injection amount in the engine 5 is adjusted by the change in the throttle position so that the driving force (rotation speed) of the engine 5 can be adjusted.

In this embodiment, detection signals corresponding to the exhaust gas temperature and the engine speed are sent to the controller 4 by the above-described sensors to detect the operating state of the engine. The rotational speed output is estimated from the operating state. Referring to the zone restriction area shown in FIG. 3, which is stored in advance according to the rotational speed output, the zone that is outside the zone restriction, the self-renewable area, and the self-renewable area, and in which area the current operating state is The controller 4 determines whether this is the case.
In addition to the method described above, a method of combining the engine exhaust temperature, the coolant temperature, the intake air amount and the like based on the rotation speed and the fuel injection amount may be used as the operating state detection means. The fuel injection amount can be estimated from the injection period in the case of the electronic injection type, and from the rack position and the engine speed in the case of the mechanical pump.

  In such a configuration, as shown in FIG. 4, the engine speed sensor 21 and the exhaust gas temperature sensor 19, which are operating state detection means, detect the engine speed and the exhaust gas temperature, and send them to the controller 4. Then, the controller 4 estimates the rotation speed output from the current operation state, and determines whether or not the particulate filter 1 is in the self-regeneration region based on a map (FIG. 3) stored in advance. When it is determined by the controller 4 that the current operation state is out of the self-regeneration region and out of the exhaust gas restriction zone restriction region, that is, when it is determined that it is outside the self-regeneration region (see FIG. 3). The controller 4 shortens the hydraulic cylinder 18 to open the bypass control valve 11, and the exhaust gas 10 bypasses the particulate filter 1. Most of the exhaust gas 10 is sent to the outlet portion 3 and exhausted through the outlet pipe 14 due to ventilation resistance. If it is determined that the region is a self-renewable region, the controller 4 extends the hydraulic cylinder 18 and the bypass control valve 11 is closed, and the exhaust gas 10 is introduced into the particulate filter 1 through the inlet 2. The

  In this way, in the diesel engine black smoke purification apparatus 20 having either one or both of the oxidation catalyst and the particulate filter 1 inside, the detection means for detecting the operating state of the engine, and the black smoke based on the operating state When the engine 4 is out of the self-regeneration area of the particulate filter 1 and out of the exhaust gas restriction zone restriction area, the exhaust gas 10 is particulate when the engine 4 is a control means for controlling the purification device 20. By providing the bypass means for bypassing the filter 1, when the particulate filter 1 is in a region where self-regeneration is not possible, the filter 1 can be bypassed for operation. This eliminates the need for forced regeneration when the exhaust gas is at a low temperature. In addition, when using the particulate filter 1, it is possible to always operate in an area where self-regeneration is possible. Specifically, in the area where self-regeneration is not possible, the load is low and the fuel injection amount is small, and in general, both PM and NOx emissions are low, and it is possible to enter the mode regulation without using the particulate filter 1 in this area. Therefore, the particulate filter 1 can be bypassed.

Next, a method for determining the engine acceleration mode, the start mode, and the transient operation state will be described.
In general, PM is easily generated in the acceleration mode or at the start, and PM can be reduced by passing through the particulate filter 1 during this period.
There are several methods for determining the acceleration mode. In this embodiment, when the difference between the throttle position and the actual engine operating state is large, it is assumed that the acceleration mode is entered, and the actual engine speed is the target rotation of the throttle (throttle throttle). It is determined that the time point at which the position (position) has been reached is out of the acceleration mode.
Specifically, as described above, the lever position of the operation lever 23 is detected by the position sensor 24, and a signal corresponding to the lever position is input to the controller 4. At this time, the controller 4 recognizes the throttle position to be changed by the input signal. Further, a detection signal of the actual engine speed is input to the controller 4 by the engine speed sensor 21. If the controller 4 determines that the throttle position and the engine speed at this time have a predetermined difference or more, it is assumed that the acceleration mode has been entered. Similarly, it is assumed that the controller 4 leaves the acceleration mode when the actual engine speed reaches the target rotation with respect to the throttle position (target rotation).
In addition, as a method for determining an acceleration mode different from the above, there is an acceleration mode when the rotation differential value is a certain numerical value or more, and each determination method for the acceleration mode can be used as appropriate.

  As a method for determining the start mode, it is determined that the engine reaches a certain target rotational speed (70% of the rated speed, etc.) from the start and shifts to the normal operation mode. In the transient state, the vehicle frequently goes back and forth between the reproducible region and the impossible region, and the bypass control valve 11 repeatedly closes and opens, and the operating state may become unstable due to the difference in exhaust back pressure. In this case, the controller 4 controls the bypass so as not to emit PM.

As a method of determining the transient operation state, the method is determined to be a transient state when the absolute value of the differential value, which has been rotated as in the acceleration mode, is greater than a certain value, or the load / rotation speed is below a certain reference There is a determination method or the like in which the case of being within the width is a transient state, and the determination method can be appropriately selected.
The determination method as described above is stored in the controller 4 in advance, and in this embodiment, the controller 4 controls the bypass control valve 11 according to whether it is in the start mode, the acceleration mode, or the transient operation state, as will be described later. It is determined whether to operate and bypass the exhaust gas 10.

Next, a control method related to opening and closing of the bypass pipe 6 will be described with reference to FIG.
First, the engine speed and the exhaust gas temperature are detected by the engine speed sensor 21 and the exhaust gas temperature sensor 19, respectively, and a signal is output to the controller 4. First, the operation state of the engine 5 is grasped by the controller 4 (step S10). Whether or not it is a bypass open region based on a map (see FIG. 3) showing the zone restriction region / recoverable region and non-renewable region shown on the relationship diagram between the rotational speed and torque stored in advance from the operating state in step S10 Is judged. If it is not the bypass open region, the bypass control valve 11 is closed (step 60). If it is determined that the bypass is open, it is determined in step 30 whether the acceleration mode or the start mode described above. If it is determined that the acceleration mode or the start mode is selected, the bypass control valve 11 is closed (step 60). If it is determined that the engine is not in the acceleration mode or the start mode, it is determined in step 40 whether or not the engine 5 is in a transient operation state. When it is determined that the engine 5 is in the transient operation state, the bypass control valve 11 is closed (step 60). If it is determined that the engine 5 is not in a transient operation state, the bypass control valve 11 is opened (step 50). In addition, as shown in FIG. 3, the operating state of the valve open (bypass open) and the operating state of the valve closed (bypass closed) are widened within the reproducible range to stabilize the operating state. The flow in that case is as shown in FIG.
In step 10 (understanding the operating state) described above, the engine speed and the exhaust gas temperature are monitored and the operating state is ascertained, but there is no particular limitation, and only the exhaust gas temperature is used. It does not matter if you know the driving condition. This will be described in detail below.

Next, the opening / closing control of the bypass passage by the exhaust gas temperature will be described.
The control method related to the opening and closing of the bypass pipe 6 described above is performed based on the engine operating state. For example, whether or not the particulate filter 1 can be self-regenerated depends greatly on the exhaust gas temperature, so that the operating state detecting means for the engine 5 is Even when the opening and closing of the bypass pipe 6 that is a bypass passage is controlled according to only the exhaust gas temperature among the engine speed and the exhaust gas temperature, as shown in FIG. The exhaust gas 10 can bypass the filter 1 when out of the zone regulation region. Of course, it is possible to use a smaller exhaust gas purifier with a wider reproducible range by grasping the operating condition including the engine speed and controlling the opening and closing, but it is possible to use a smaller exhaust gas purification device, but the opening and closing control is performed only by detecting the exhaust gas temperature. For example, there is an advantage that the configuration of the map and the detection device that are determined in advance is simplified.
Further, when opening / closing control is performed based on detection of exhaust gas temperature, as shown in FIG. 3, there is a slight history in the opening start temperature (temperature at which the bypass control valve is opened) and closing end temperature (temperature at which the bypass control valve is closed). However, if both are set in the reproducible area outside the zone regulation, it is possible to take a countermeasure in consideration of the regulation margin.

As described above, when the controller 4 as the control means determines that the engine operating state is the transient operation state, the start mode or the acceleration mode, the bypass means does not bypass the exhaust gas 10, thereby During start-up or during a transient state, PM emission can be reduced by passing the exhaust gas 10 through the particulate filter 1 without using a bypass while PM is easily generated.
The bypass means includes a bypass pipe 6 serving as a bypass passage and a bypass control valve 11 serving as a bypass passage opening / closing valve. The opening / closing of the bypass control valve 11 is performed electrically, hydraulically or pneumatically. By using the controller 4, it is possible to perform reliable opening / closing control of the bypass passage in accordance with the engine operating condition.
Further, by opening / closing the bypass control valve 11 by detecting the exhaust gas temperature, it is possible to control the opening / closing of the bypass by the exhaust gas temperature. Further, the exhaust gas temperature range to be opened and closed is outside the zone regulation, and the zone regulation can be dealt with.

Next, another embodiment of the black smoke purification device provided with the bypass means will be described with reference to FIG.
As shown in FIG. 5, the black smoke purification device 40 includes an inlet portion 22 and a particulate filter storage portion 26 that stores the particulate filter 1. The bypass means 27 includes a bypass passage 28 for bypassing the exhaust gas 10 and a bimetal valve 29 serving as a bypass passage opening / closing valve capable of opening and closing the bypass passage.
The inlet 22 and the particulate filter storage 26 are formed in the housings 30a and 30b, respectively. The particulate filter 1 has a gap of a predetermined interval between the outer periphery of the particulate filter 1 and the inside of the housing 30b, and the gap forms a bypass passage 28 that bypasses the particulate filter 1. is doing. Further, an outlet pipe 34 for discharging the exhaust gas 10 is communicated with the rear portion of the particulate filter 1. A bimetal valve 29 serving as a bypass passage opening / closing valve is disposed in the middle of the outlet pipe 34. The front end of the housing 30 b is kept airtight by the rear end of the housing 30 a of the inlet portion 22 and the gasket 15, and is integrally fixed by the V-shaped band 12. Further, the front end of the bypass passage 28 is always open, and even when the front end of the housing 30b is connected to the rear end of the housing 30a, the exhaust gas 10 passes through the bypass passage 28 along the inner walls of the housings 30a and 30b from the inlet portion 22. It is possible to pass. The heat insulating sound absorbing material 8 is disposed in the inlet portion 22, and the heat insulating sound absorbing material 8 is pressed against the inner wall of the inlet portion 2 by the heat insulating sound absorbing material pressing plates 13 and 16.
The particulate filter 1 is detachably attached to the particulate filter storage unit 26.

  An inlet pipe 36 that guides the exhaust gas 10 introduced through the exhaust pipe 9 is disposed in the inlet portion 22. The inlet pipe 36 is inserted through the inlet portion 2 in a substantially vertical direction, has an opening for connecting to the exhaust pipe 9 at one end, and is sealed at the other end. A number of small holes 36 a are provided in the cylindrical side wall of the inlet pipe 36. The exhaust gas 10 enters the inlet portion 22 through the small hole 36a.

In such a configuration, when the exhaust gas 10 is led from the inlet portion 22 through the bypass passage 28 to the vicinity of the bimetal valve 29, which is a self-contained temperature sensitive valve, the exhaust gas 10 is a temperature sensitive member of the bimetal valve 29. The bimetal portion is configured to sense the temperature, and the bimetal valve 29 is opened and closed according to the reached temperature level. That is, when the exhaust gas 10 having a temperature equal to or higher than the predetermined temperature is introduced in the vicinity of the bimetal valve 29, the bimetal portion is heated and curved, and the exhaust gas 10 can enter the outlet pipe 34. When the bimetal valve 29 is thus opened, most of the exhaust gas 10 is led to the bypass passage 28 due to the ventilation resistance of the particulate filter 1 and is exhausted through the outlet pipe 34. On the other hand, when the exhaust gas 10 is lower than the predetermined temperature, the bimetal portion becomes flat, the bimetal valve 29 is closed, and the bypass passage 28 is blocked.
Further, the exhaust gas 10 flows through the bypass passage 28 facing the outer peripheral portion of the particulate filter 1, so that the periphery of the particulate filter 1 can be always warmed regardless of whether the bimetal valve 29 is opened or closed.
Regarding the temperature condition for opening and closing the bimetal valve 29, the specification of the bimetal that is a temperature sensitive member, that is, the temperature sensitive condition range may be selected as appropriate in consideration of the torque map shown in FIG.
In this embodiment, a bimetal valve is used as a self-contained temperature-sensitive valve. However, there is no particular limitation, and a valve made of wax pellets, shape memory alloy, or the like is used as a temperature-sensitive member of the temperature-sensitive valve. It doesn't matter.

In this way, the bypass passage opening / closing valve is constituted by the bimetal valve 29 which is a self-contained temperature sensitive valve, so that the bypass can be opened / closed according to the exhaust gas temperature condition without using a control means or a temperature sensor. It can be carried out. Moreover, the temperature of gas can always be detected by providing a temperature sensing part after joining.
Further, since the bypass passage 28 is formed in the outer peripheral portion of the particulate filter 1, the exhaust gas 10 flows around the particulate filter 1 even when the exhaust gas 10 flows through the bypass passage 28. Cooling can be prevented, the filter 1 itself can be brought close to the gas temperature, the bypass passage on-off valve can be closed, and even if exhaust gas is suddenly introduced into the filter 1, it can be made less susceptible to thermal shock.

Next, another embodiment of the black smoke purification apparatus provided with a bypass passage will be described with reference to FIG.
As shown in FIG. 6, the black smoke purification device 60 includes an inlet portion 42, an oxidation catalyst (DOC) 32, and a particulate filter storage portion 46 that stores the particulate filter 1. The bypass means 47 includes a bypass passage 48 that bypasses the exhaust gas 10 and a bypass control valve 59 that serves as a bypass passage on-off valve that can open and close the bypass passage 48.
The inlet 42 and the oxidation catalyst (DOC) 32 are disposed in the housing 50a. The particulate filter storage 46 is formed in the housing 50b. The particulate filter 1 has a gap of a predetermined interval between the outer periphery of the particulate filter 1 and the inside of the housing 50b, and the gap forms a bypass passage 48 that bypasses the particulate filter 1. is doing. In addition, an outlet pipe 54 for discharging the exhaust gas 10 communicates with the rear part of the particulate filter 1. A bypass control valve 59 is disposed in the middle of the outlet pipe 54. The front end of the housing 50 b is kept airtight with the rear end of the housing 50 a and the gasket 15, and is fixed integrally with the V-shaped band 12. Further, the front end of the bypass passage 48 is always open, and even when the front end of the housing 50b is connected to the rear end of the housing 50a, the exhaust gas 10 passes through the bypass passage 48 along the inner wall of the housing 50a, 50b from the inlet portion 42. It is possible to pass. The heat insulating sound absorbing material 8 is disposed in the inlet portion 42, and the heat insulating sound absorbing material 8 is pressed against the inner wall of the inlet portion 42 by the heat insulating sound absorbing material pressing plates 13 and 16. An oxidation catalyst 32 is disposed downstream of the inlet portion 42 and is housed in the housing 50a in the same manner as the inlet portion 42.
The particulate filter 1 and the oxidation catalyst 32 are detachable from the particulate filter storage 46 and the inlet 42, respectively.
Although omitted in the present embodiment, the configuration other than the main body of the black smoke purification device 60, that is, the engine 5, the controller 4, the operation lever 23, and various sensors are the same as those in the first embodiment. Further, the controller 4 is configured to be able to perform opening / closing control of the bypass control valve in the same manner as in the first embodiment.

  An inlet pipe 56 that guides the exhaust gas 10 introduced through the exhaust pipe 9 is disposed at the inlet portion 42. The inlet pipe 56 is inserted through the inlet portion 42 in a substantially vertical direction, and an opening for connecting to the exhaust pipe 9 is provided at one end, and the other end is sealed. A number of small holes 56 a are provided in the cylindrical side wall of the inlet pipe 56. The exhaust gas 10 enters the inlet portion 42 through the small hole 56a.

The bypass control valve 59 has a valve 59a, and one end of the valve 59a is fixed to one end of a cylinder lot of an electric actuator 58 which is an example of an actuator, and the electric actuator 58 is a control means. It is connected to the controller 4. By driving the electric actuator 58 with the valve 59a, the flow passage area from the bypass passage 48 to the outlet pipe 54 can be changed. The electric actuator 58 can be constituted by a motor or a solenoid.
Further, as in the second embodiment, the exhaust gas 10 flows through the bypass passage 48 facing the outer periphery of the particulate filter 1 so that the surroundings of the particulate filter 1 can be always warmed regardless of whether the bypass control valve 59 is opened or closed. It has become.

In such a configuration, when the bypass control valve 59 is closed, the exhaust gas 10 is introduced from the inlet pipe 56 into the inlet portion 42 through the small hole 56a, and passes through the oxidation catalyst 32 from the inlet portion 42. Subsequently, it passes through the particulate filter 1 at the rear stage of the oxidation catalyst 32, enters the outlet pipe 54, and is discharged from the outlet pipe 54. On the other hand, when the bypass control valve 59 is opened, the exhaust gas 10 is introduced from the inlet pipe 56 into the inlet portion 42 through the small hole 56 a and passes through the oxidation catalyst 32 from the inlet portion 42. Subsequently, the exhaust gas 10 hardly flows into the filter 1 due to the ventilation resistance of the particulate filter 1 at the rear stage of the oxidation catalyst 32 and flows from the rear portion of the oxidation catalyst 32 to the bypass passage 48 to be mainly Then, the gas is introduced into the outlet pipe 54 in the particulate filter storage 46 through the bypass passage 48 and discharged from the outlet pipe 54.
The opening / closing control of the bypass control valve 59 by the controller 4 can be performed in the same manner according to the control flow for opening and closing the bypass passage shown in FIG. Thus, the controller 4 controls the opening / closing of the bypass control valve 59 so that the exhaust gas 10 bypasses the particulate filter 1.

  In this way, in the black smoke purification device for a diesel engine in which the oxidation catalyst 32 is arranged at the front stage and the particulate filter 1 is arranged at the rear stage, the bypass passage 48 bypasses the exhaust gas 10 after the oxidation catalyst 32. By passing at least the oxidation catalyst 32, it becomes possible to remove even a little HC component, and PM can be reduced.

The figure which shows the example which examined the self-regenerative area on the rotation-torque diagram of an industrial engine. The figure which shows the example of a zone regulation. The figure which shows a zone control area | region / reproducible area | region and a nonreproducible area | region. Schematic which shows the black smoke purification apparatus for diesel engines which concerns on this invention. Schematic which shows the black smoke purification apparatus for diesel engines in Example 2. FIG. Schematic which shows the black smoke purification apparatus for diesel engines in Example 3. FIG. The figure which shows the control flow of opening and closing of a bypass passage. The block diagram which shows a control means. The figure which shows the control flow with hysteresis of opening and closing of a bypass channel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Particulate filter 4 Controller 5 Engine 6 Bypass pipe 10 Exhaust gas 11.59 Bypass control valve 18 Hydraulic cylinder 19. Exhaust gas temperature sensor 20.40.60 Black smoke purification device 21 Engine speed sensor 28.48 Bypass passage 29 Bimetal valve 32 Oxidation catalyst 58 Electric actuator

Claims (8)

  In a black smoke purification apparatus for a diesel engine that includes either or both of an oxidation catalyst and a particulate filter, a detection unit that detects an operation state of the engine, and controls the black smoke purification apparatus based on the operation state And a bypass means for bypassing the particulate filter when the engine operating state is outside the self-regeneration area of the particulate filter and outside the zone restriction area of the exhaust gas restriction. Black smoke purification device for diesel engines.   2. The diesel engine according to claim 1, wherein when the control unit determines that the engine operation state is a transient operation state, a start mode, or an acceleration mode, the bypass unit does not bypass the exhaust gas. Black smoke purification device.   2. The bypass means includes a bypass passage and a bypass passage opening / closing valve, and the bypass passage opening / closing valve is opened / closed by the control means by electric drive, hydraulic drive, or pneumatic drive. Or the black smoke purification apparatus for diesel engines of Claim 2.   4. The black smoke purification apparatus for a diesel engine according to claim 3, wherein the bypass passage on-off valve is opened and closed by detecting an exhaust gas temperature.   The diesel engine black smoke purification device according to claim 4, wherein the bypass passage opening / closing valve is a self-contained temperature-sensitive valve.   6. The diesel engine black smoke purification device according to claim 5, wherein the temperature sensitive member of the temperature sensitive valve is made of wax pellets, shape memory alloy or bimetal.   The black smoke purification device for a diesel engine according to claim 3, wherein the bypass passage is formed in an outer peripheral portion of the particulate filter.   2. The diesel engine black smoke purification apparatus in which the oxidation catalyst is disposed in the front stage and the particulate filter is disposed in the rear stage, wherein the bypass passage bypasses the exhaust gas after the oxidation catalyst. Black smoke purification device for diesel engines.