JP2010168972A - Exhaust emission control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system capable of raising exhaust gas temperature of an engine without wastefully consuming the power of the engine. <P>SOLUTION: The system includes an exhaust emission control device 70 including an oxidation catalyst 73 and a particulate filter 74 and purifying the exhaust gas of the engine 20, a first alternator 26 generating electric power by being driven by the power of the engine 20 and supplying the electric power to electric equipment, and a second alternator 27 generating electric power by being driven by the power of the engine 20 and applying a load on the engine 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technology of an exhaust purification system that removes particulate matter contained in exhaust gas of a diesel engine.

  Conventionally, in an engine exhaust gas flow path, an oxidation catalyst is disposed upstream of a DPF (Diesel Particulate Filter), and the collected particulate matter is continuously oxidized and removed to regenerate the DPF. A regenerative DPF is known (see Patent Document 1).

  Further, in the self-regenerating DPF, in order to keep the temperature of the DPF and the oxidation catalyst at an appropriate temperature (for example, about 300 ° C.), an exhaust throttle is provided in the exhaust passage of the engine, and a load is applied to the engine. A technique for increasing the exhaust temperature is also known.

  However, the configuration in which the engine is loaded with the exhaust throttle as described above is disadvantageous in that the power of the engine is wasted.

Japanese Patent No. 3012249

  The present invention has been made in view of the above situation, and provides an exhaust purification system capable of raising the exhaust temperature of the engine without wasting power of the engine unnecessarily.

In claim 1,
An exhaust purification device that has an oxidation catalyst and a particulate filter and purifies the exhaust of the engine;
A first alternator that generates electric power by being driven by the power of the engine and supplies electric power to the electrical device;
A second alternator that generates power by being driven by the power of the engine and applies a load to the engine;
It comprises.

In claim 2,
The second alternator is
A clutch for connecting and disconnecting transmission of power from the engine to the second alternator is provided.

In claim 3,
The clutch is constituted by an electromagnetic clutch,
Temperature detection means for detecting the temperature of the exhaust of the engine, the oxidation catalyst, or the particulate filter;
Control means for interrupting transmission of power by the clutch when the temperature detected by the temperature detection means is equal to or higher than a set temperature;
It comprises.

  The present invention has an effect that the exhaust temperature of the engine can be raised without wasting power of the engine.

The side view which shows the whole structure of the power shovel which comprises an exhaust gas purification system. The plane schematic diagram which shows the structure inside a bonnet. The rear schematic diagram which shows the structure inside a bonnet. The side view which shows the structure of an engine. Schematic which shows the structure of an exhaust gas purification apparatus. The figure which shows the outline | summary of an exhaust gas purification system.

  Hereinafter, an exhaust purification system 100 according to an embodiment of an exhaust purification system according to the present invention will be described with reference to the drawings.

  First, the overall configuration of the power shovel 1 including the exhaust purification system 100 will be described with reference to FIG. The exhaust purification system 100 according to the present embodiment is not limited to that provided in the power shovel 1, and may be provided in other agricultural work vehicles, civil engineering work vehicles, or the like. .

  As shown in FIG. 1, the power shovel 1 mainly includes a crawler type traveling device 2, a main body frame 3, an operation unit 4, a bonnet 5, a work machine 6, and a blade 7.

  The crawler type traveling device 2 is a traveling device for traveling the power shovel 1. The main body frame 3 is a member constituting the main structure of the power shovel 1. The main body frame 3 is mounted on the crawler type traveling device 2 so as to be able to turn left and right.

  The operation unit 4 is disposed on the upper part of the main body frame 3 and includes various operation levers, foot pedals, and the like. The bonnet 5 is provided in a circular arc shape at the rear part of the main body frame 3 and mainly houses and covers an engine 20, a hydraulic pump 30, a hydraulic oil tank 40, a radiator 50, and an exhaust purification device 70, which will be described later. To do. A seat 5 a is attached to the top of the bonnet 5. A step portion 3 a is formed on the upper surface of the main body frame 3 and in the vicinity of the operation portion 4.

  The work implement 6 is provided at the front end portion of the main body frame 3, and mainly includes a boom 6a, an arm 6b, a bucket 6c, a boom cylinder 6d, an arm cylinder 6e, and a bucket cylinder 6f. A boom bracket 6g is pivotally supported at the front end portion of the main body frame 3 so as to be turnable left and right. One end of the boom 6a is pivotally supported by the front end of the boom bracket 6g. One end of the arm 6b is pivotally supported by the other end of the boom 6a. One end of the bucket 6c is pivotally supported by the other end of the arm 6b. The work implement 6 is configured such that the boom 6a can be turned up and down by the boom cylinder 6d, the arm 6b can be turned up and down by the arm cylinder 6e, and the bucket 11 can be turned up and down by the bucket cylinder 6f. The blade 7 protrudes from the rear end portion of the crawler traveling device 2 and is supported by a lift cylinder (not shown) so as to be vertically rotatable.

Next, the internal configuration of the bonnet 5 will be described with reference to FIGS.
As described above, the bonnet 5 mainly houses and covers the engine 20, the hydraulic pump 30, the hydraulic oil tank 40, the radiator 50, and the exhaust purification device 70.

  As shown in FIGS. 2 and 3, the engine 20 is provided at the center of the rear end of the main body frame 3 via an engine support member 21. The engine 20 is provided with a flywheel (not shown) on the left side in the figure. The flywheel is housed in a flywheel case 22. The engine 20 includes an exhaust pipe 23 for exhausting combustion gas (exhaust gas) at the top. The engine 20 is provided with a cooling fan 24 on the right side of the figure.

  As shown in FIG. 4, one end of the crankshaft (output shaft) of the engine 20 protrudes from the right side surface of the engine 20, and a crank pulley 25a is fixed to the one end. A cooling fan 24 is disposed above the crank pulley 25a, and the fan pulley 24a is connected to the cooling fan 24.

  A first alternator 26 is disposed on the side of the cooling fan 24 (on the right side of the drawing), and a first pulley 26 a is connected to the first alternator 26. The first alternator 26 is connected to a display device such as a lamp provided in the power shovel 1 and various electric devices such as a control device and a light, and generates electric power to be supplied to them.

A second alternator 27 is disposed below the first alternator 26 and on the side of the crank pulley 25a (on the right side in the drawing). The second alternator 27 is connected to the second pulley 27a. The second alternator 27 applies a load to the engine 20 and generates power using the power of the engine 20. The second alternator 27 is connected to a heater 76 for increasing the temperature of the exhaust gas of the engine 20 when an oxidation catalyst 73 or the like described later is at a low temperature, or an electric device that consumes electric power instead of the heater 76.
The arrangement position of the second alternator 27 is not limited, and is arranged in an empty space such as above the first alternator 26 or below the crank pulley 25a and within a range where the belt 28 can be wound. It is also possible.

  One belt 28 is wound around the crank pulley 25a, the fan pulley 24a, the first pulley 26a, and the second pulley 27a. The power of the engine 20 is transmitted through the crankshaft and the belt 28, and the cooling fan 24, the first alternator 26, and the second alternator 27 are driven.

  As shown in FIGS. 2 and 3, the hydraulic pump 30 is provided on the flywheel case 22 side of the engine 20 (the left side in the figure of the engine 20). The hydraulic pump 30 is connected to and driven by the crankshaft of the engine 20.

  The hydraulic oil tank 40 is a tank that stores hydraulic oil for hydraulic equipment, and is provided at the left end of the main body frame 3 in the drawing (the left side of the engine 20 in the drawing). The hydraulic oil tank 40 has a hydraulic hose 40a connected to the lower side surface. The hydraulic oil in the hydraulic oil tank 40 is supplied to the hydraulic pump 30 through the hydraulic hose 40a.

  The radiator 50 is a device for dissipating (cooling) excessive heat generated in the engine 20. The radiator 50 is connected to the right side of the cooling fan 24 (the right side of the engine 20 in the drawing) and is disposed at a predetermined interval from the side wall of the bonnet 5. A duct 50a is provided between the radiator 50 and the side wall of the bonnet 5 so that the cooling air from the cooling fan 24 can be discharged to the outside from the duct 50a. A louver 50b is provided in the duct 50a, and the direction of the cooling air from the cooling fan 24 can be changed.

  The exhaust purification device 70 is a device that removes particulate matter contained in the exhaust gas of the engine 20. The exhaust purification device 70 is accommodated in an exhaust purification device cover 60 that is formed of a hexagonal cylindrical member in cross-section. The exhaust purification device 70 is disposed above the hydraulic pump 30 and between the engine 20 and the hydraulic oil tank 40, and is provided so that the longitudinal direction thereof substantially coincides with the front-rear direction of the power shovel 1. The exhaust purification device 70 has an exhaust pipe 23 of the engine 20 connected to the upper outer peripheral surface thereof. Exhaust gas exhausted from the engine 20 is introduced into the exhaust purification device 70 via the exhaust pipe 23.

  Here, each structure of the exhaust emission control device 70 will be described with reference to FIG. The exhaust purification device 70 mainly includes a casing 71, an inlet portion 72, an oxidation catalyst 73, a particulate filter 74, an outlet portion 75, a heater 76, and a temperature detection means 77.

  The casing 71 is a member that forms a main structure of the exhaust purification device 70. Other members constituting the exhaust purification device 70 are attached to the casing 71. The housing 71 includes a first housing portion 71a, a second housing portion 71b, and a third housing portion 71c.

The first housing 71a is a cylindrical member that is open at the right side in the figure and closed at the left side in the figure.
The second casing 71b is a cylindrical member that is open at both ends. The illustrated left end of the second casing 71b is connected to the illustrated right end of the first casing 71a.
The third casing 71c is a cylindrical member that is open at the left side in the figure and closed at the right side in the figure. The illustrated left end of the third casing 71c is connected to the illustrated right end of the second casing 71b.

The inlet portion 72 is a portion that guides exhaust gas exhausted from the engine 20 into the housing 71. The inlet 72 is provided in the left end of the exhaust purification device 70 in the first casing 71a. The inlet portion 72 includes an inlet pipe 72a.
The inlet pipe 72 a is an inlet portion for exhaust gas exhausted from the engine 20. As shown in FIG. 2, the inlet pipe 72a is provided on the engine 20 side of the exhaust purification device 70 and protrudes from the outer peripheral surface of the first housing portion 71a. One end of the exhaust pipe 23 connected to the exhaust manifold of the engine 20 is connected to one end of the inlet pipe 72a.

  The oxidation catalyst 73 is a substantially cylindrical member, and is provided in the first housing portion 71a. The oxidation catalyst 73 has a monolith carrier (not shown) in which grid-like (honeycomb-like) passages are formed in the flow direction of the exhaust gas. A catalytic metal such as platinum, rhodium or palladium is supported on the monolith support. By supporting such a catalytic metal, the oxidation catalyst 73 is given an oxidizing power for oxidizing NO, CO, HC, and the like. The NO oxidized in the oxidation catalyst 73 becomes NO 2 and is supplied to the particulate filter 74.

  The particulate filter 74 is a substantially cylindrical honeycomb filter, and is provided in one end of the first casing 71a and in the second casing 71b. The particulate filter 74 has a polygonal cross section partitioned by porous partition walls made of ceramics such as cordierite. The particulate filter 74 is configured by substantially sealing alternately adjacent inlet portions and outlet portions of a large number of through holes formed in parallel with each other by these partition walls. The partition walls are coated with a catalytic metal such as Pt to carry a catalytic function. By adopting such a configuration, in the particulate filter 74, when the exhaust gas of the engine introduced from the inlet side of the particulate filter 74 passes through the porous partition wall, PM composed of particulates contained in the exhaust gas. The exhaust gas from which PM has been removed is discharged from the outlet portion 75.

  Further, the PM filtered by the particulate filter 74 and deposited on the particulate filter 74 is oxidized by NO 2 supplied from the oxidation catalyst 73 and removed from the particulate filter 74. Hereinafter, removing PM deposited on the particulate filter 74 by this chemical reaction is simply referred to as “regeneration”.

  In order to actively cause regeneration in the particulate filter 74, it is desirable to keep the temperatures of the oxidation catalyst 73 and the particulate filter 74 at about 300 ° C. or higher. For this reason, it is necessary to keep the exhaust temperature T of the engine 20 at a high temperature.

  The outlet portion 75 discharges the exhaust gas to the outside of the casing 71, and is provided in the third casing portion 71c and at the right end of the exhaust purification device 70 in the figure. The outlet part 75 includes an outlet pipe 75a and a resonance pipe 75b.

  The outlet pipe 75 a is an exhaust gas outlet portion in the housing 71. The outlet pipe 75a passes through the outlet portion 75 in a substantially horizontal direction. The outlet pipe 75a is formed in a cylindrical shape, and the left end portion in the drawing is opened to introduce exhaust gas that has passed through the particulate filter 74, and the right end portion in the drawing is opened to discharge the exhaust gas to the outside of the casing 71. Is done. The right end portion of the outlet pipe 75a shown in the figure is inserted through the bonnet 5 and protrudes outside the bonnet 5.

  The resonance tube 75b is a member that reduces noise when exhaust gas is discharged. The resonance tube 75b is a substantially cylindrical member arranged in parallel with the outlet tube 75a. Both ends of the resonance tube 75b are open. The axis of the resonance tube 75b is provided in the third casing 71c in a state parallel to the axis of the outlet tube 75a.

  The heater 76 raises the temperature of surrounding air by generating heat, and is disposed in the inlet portion 72. By operating the heater 76, the temperature of the exhaust of the engine 20 introduced into the inlet 72 can be raised.

  The temperature detecting means 77 is for detecting the temperature of the surrounding air, and is arranged in the inlet pipe 72a. The temperature detection means 77 can detect the temperature T (hereinafter simply referred to as “exhaust temperature”) T of the engine 20 introduced into the exhaust purification device 70 via the inlet pipe 72a.

  As described above, the exhaust purification device 70 is disposed so that the longitudinal direction thereof substantially coincides with the front-rear direction of the power shovel 1. Specifically, the inlet portion 72 is disposed on the front side of the excavator 1 and the outlet portion 75 is disposed on the rear side of the excavator 1. In this embodiment, the oxidation catalyst 73 and the particulate filter 74 are arranged in the exhaust purification device 70. However, only the oxidation catalyst 73 or only the particulate filter 74 is arranged in the exhaust purification device 70. It does not matter as a configuration.

  Hereinafter, the exhaust purification system 100 will be described with reference to FIG. The exhaust purification system 100 purifies the exhaust while adjusting the exhaust temperature T of the engine 20 by applying an appropriate load to the engine 20. The exhaust purification system 100 mainly includes an engine 20, a first alternator 26, a second alternator 27, an exhaust purification device 70, and a control means 80.

  The second pulley 27a is connected to the second alternator 27 via the clutch 27b. The clutch 27b is configured by an electromagnetic clutch.

  The control means 80 switches connection / disconnection of the clutch 27b based on the detection result by the temperature detection means 77. The control means 80 is connected to the temperature detection means 77 and the clutch 27b. The control unit 80 can receive the detection result by the temperature detection unit 77. Moreover, the control means 80 can switch the presence or absence of power transmission between the 2nd alternator 27 and the 2nd pulley 27a by switching connection / disconnection of the clutch 27b.

  Further, the second alternator 27 is connected to the heater 76, and the heater 76 is activated by the electric power generated when the second alternator 27 is driven, so that the exhaust temperature T of the engine 20 can be raised.

  Below, the operation | movement aspect of the exhaust gas purification system 100 comprised as mentioned above is demonstrated.

  The control means 80 stores a reference temperature (hereinafter simply referred to as “set temperature”) Te for switching the connection / disconnection of the clutch 27b. The set temperature Te is determined based on experiments, numerical calculations, and the like. The set temperature Te can be stored in advance, or can be changed to a desired value using an input unit.

  When the exhaust temperature T of the engine 20 detected by the temperature detection means 77 is equal to or higher than the set temperature Te, the control means 80 disconnects the clutch 27b, so that the gap between the second alternator 27 and the second pulley 27a is reached. Shut off power transmission. In this case, since the power of the engine 20 is not transmitted to the second alternator 27, the second alternator 27 does not operate. Therefore, there is no power loss of the engine 20 for rotating the second alternator 27. Moreover, since the 2nd alternator 27 does not operate | move, electric power is not supplied to the heater 76 and the heater 76 does not operate | move.

  When the exhaust temperature T of the engine 20 detected by the temperature detecting means 77 is lower than the set temperature Te, the control means 80 connects the second alternator 27 and the second pulley 27a by connecting the clutch 27b. Enables transmission of power. In this case, the power of the engine 20 is transmitted to the second alternator 27, and the second alternator 27 operates. Further, the electric power generated by the second alternator 27 is supplied to the heater 76, and the heater 76 is activated.

  Note that, in any case where the exhaust temperature T is equal to or higher than the set temperature Te or lower than the set temperature Te, the first alternator 26 is operated by the power of the engine 20. The electric power generated by the first alternator 26 is supplied to various electric devices included in the power shovel 1.

  As described above, when the exhaust temperature T is lower than the set temperature Te, a load can be applied to the engine 20 by operating the second alternator 27 with the power of the engine 20. As a result, the fuel injection amount is increased and the exhaust temperature T of the engine 20 can be raised. Further, by raising the exhaust temperature T of the engine 20, the temperatures of the oxidation catalyst 73 and the particulate filter 74 can be raised, and regeneration in the particulate filter 74 can be actively performed.

  In addition, since the second alternator 27 is used to apply a load to the engine 20, power can be generated by the second alternator 27. Therefore, the engine 20 can be loaded without wasting power. Can be added.

  Further, by providing the second alternator 27 with the clutch 27b, it is possible to switch whether the second alternator 27 has a load on the engine 20 or not. By switching the clutch 27b, a load is applied to the engine 20 only when desired, and the exhaust temperature T can be raised.

  In addition, the exhaust temperature T of the engine 20 can be automatically controlled by switching the connection / disconnection of the clutch 27b based on the exhaust temperature T by the control means 80. Further, as in the present embodiment, the exhaust temperature T can be kept at the set temperature Te or higher by applying a load to the engine 20 only when the exhaust temperature T is lower than the set temperature Te. For example, the PM accumulated on the particulate filter 74 can be efficiently removed by setting the set temperature Te to a value at which regeneration in the particulate filter 74 occurs actively.

  Further, by operating the heater 76 with the electric power generated by the second alternator 27, the exhaust temperature T can be further increased, and as a result, regeneration in the particulate filter 74 can be actively caused.

  In the present embodiment, the clutch 27b is configured by an electromagnetic clutch, but the present invention is not limited to this. That is, the clutch 27b can be constituted by a wet clutch, a dry clutch, a powder clutch, a one-way clutch, or the like. In the present embodiment, the connection / disconnection of the clutch 27b is controlled by the control means 80. However, the present invention is not limited to this. In other words, the clutch 27b can be switched between connection and disconnection by an operator's manual operation.

  In the present embodiment, the temperature detection means 77 is arranged in the inlet pipe 72a and detects the exhaust temperature T of the engine 20, but the present invention is not limited to this. That is, the temperature detection unit 77 can be configured to detect the temperature of the oxidation catalyst 73 or the particulate filter 74. In this case, the control unit 80 switches the connection / disconnection of the clutch 27 b based on the temperature of the oxidation catalyst 73 or the particulate filter 74 detected by the temperature detection unit 77.

  In the present embodiment, the power generated by the second alternator 27 is supplied to the heater 76, but the present invention is not limited to this. That is, a configuration in which the electric power generated by the second alternator 27 is supplied to the storage battery and charged, or a configuration in which the electric power is supplied to other electrical devices may be possible. In the present embodiment, the heater 76 is provided only in the exhaust purification device 70, but the present invention is not limited to this. That is, a heater is also provided in the intake manifold, the oil pan, etc., and the heater is connected to the second alternator 27 through the control means 80, and the clutch 27b is connected at the time of starting or when the outside air temperature is low to connect the intake manifold, etc. It is also possible to use a configuration in which the is heated. With this configuration, the electric power generated by the second alternator 27 can be used effectively, and the time until the engine 20 reaches stable rotation can be reduced.

DESCRIPTION OF SYMBOLS 1 Excavator 20 Engine 26 1st alternator 27 2nd alternator 27b Clutch 70 Exhaust purification device 73 Oxidation catalyst 74 Particulate filter 76 Heater 77 Temperature detection means 80 Control means 100 Exhaust purification system

Claims (3)

An exhaust purification device that has an oxidation catalyst and a particulate filter and purifies the exhaust of the engine;
A first alternator that generates electric power by being driven by the power of the engine and supplies electric power to the electrical device;
A second alternator that generates power by being driven by the power of the engine and applies a load to the engine;
An exhaust purification system comprising: The second alternator is
The exhaust purification system according to claim 1, further comprising a clutch that connects and disconnects transmission of power from the engine to the second alternator. The clutch is constituted by an electromagnetic clutch,
Temperature detection means for detecting the temperature of the exhaust of the engine, the oxidation catalyst, or the particulate filter;
Control means for interrupting transmission of power by the clutch when the temperature detected by the temperature detection means is equal to or higher than a set temperature;
The exhaust purification system according to claim 2, comprising:

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