JP2000257513A - Recirculation exhaust gas cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower as a cooling air source in an EGR cooler that cools an EGR gas with cooling air by arranging and rotating a heat exchange core member over a cooling air passage and an EGR passage. And the electric motor for rotating the core member is eliminated to improve the mountability. SOLUTION: A blower pulley 10 is provided on a first drive shaft 102 of a blower 62 for supplying cooling air to a heat exchange core member 52.
4, a first drive shaft is rotated by a belt 150 wound around a pulley 22 'for driving an auxiliary machine that is linked to the crank pulley 18 or the crank pulley, and a second drive shaft connected to the first drive shaft is rotated. The heat exchange core member is rotated via the drive shaft 124. A first clutch device 106 for power connection / disconnection is provided on the first drive shaft so that the operation of the blower can be stopped as necessary, and the second clutch device 12 is provided on the second drive shaft.
8 is provided to stop or decelerate the heat exchange core member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recirculation exhaust gas cooling system for a diesel engine mounted on an engine, particularly a truck or the like.

[0002]

2. Description of the Related Art Conventionally, in order to reduce nitrogen oxide (NO _x ), which is a harmful component in exhaust gas discharged from a diesel engine for vehicles such as trucks, a part of the exhaust gas of the engine is taken into the intake air of the engine. There is known an exhaust gas recirculation device which is mixed into a cylinder and recirculated into a cylinder to suppress a combustion temperature and a pressure. (Hereinafter, in some cases, this device is referred to as an EGR device, and recirculating exhaust gas is referred to as EGR, and recirculated exhaust gas is referred to as EGR gas.)

[0003] In the engine with the EGR device, if high-temperature exhaust gas is directly mixed into the intake air, the intake air temperature rises and the volume efficiency decreases, so that the performance of the engine such as output and fuel efficiency deteriorates. There is a problem that combustion deteriorates and other harmful components in exhaust gas such as an increase in black smoke increase. Therefore, various recirculation exhaust gas cooling devices (which reduce the intake air temperature by cooling the EGR gas, thereby relatively improving the volumetric efficiency, and improving the engine output, fuel consumption and exhaust gas performance) Less than,
In some cases, referred to as an EGR cooler) has already been proposed and put into practical use.

In the conventional EGR coolers, plate fin type and multi-tube type cooling devices having a structure essentially similar to a radiator for cooling engine cooling water are widely used. Pressure loss at the time of passing through the engine, and the volume and weight of the EGR cooler required to supply a required amount of cooled EGR gas to the engine become relatively large.

In order to improve the disadvantages of the plate fin type and the multi-tube type EGR cooler, the heat exchange element is provided with a short columnar or disk-shaped outer shape, and a plurality of heat exchangers inside thereof are substantially parallel to the center line. The ceramic heat exchange core member of the honeycomb structure, which has a small cross-sectional area inside the core, penetrates the exhaust air recirculation passage and the cooling air passage, which recirculates a part of the engine exhaust gas together with the intake air into the engine cylinder. Interposed, rotate the center line as a rotation axis,
An EG that is cooled by flowing recirculated exhaust gas through a passage in the core cooled by the cooling air.
An R cooler has already been proposed by the applicant. (1997 Patent Application No. 334742 and 1997 Patent Application No. 3
46986)

An EGR cooler provided with the above-mentioned ceramic heat exchange core member having a honeycomb structure (hereinafter sometimes referred to as an already proposed EGR cooler) has a unit volume smaller than that of a conventional plate-fin type and multi-tube type EGR cooler. More heat exchange surface area per
There is an advantage that it is possible to provide an EGR cooler that has a small pressure loss during the flow of the R gas and the cooling air, and thus is small and lightweight and has excellent mountability to a vehicle diesel engine.

An outline of the structure of the above-mentioned proposed EGR cooler will be described with reference to FIGS. First, in the schematic side view of the entire engine of FIG. 4, reference numeral 10 denotes a diesel engine for vehicles such as trucks, and 12 denotes the engine 10
, A cylinder head 14 mounted on the crankcase 12, and 16 a cylinder head 14
The EGR cooler mounted above is shown generally, and its detailed structure will be described later. Reference numeral 18 denotes a crank pulley mounted on the front end of a crankshaft 20 of the engine 10, 22 an alternator, and 24 a cooling fan. The alternator 22 and the cooling fan 24 are connected to the crankshaft 20 by a common belt 26 wound around the respective drive pulleys 22 ′, 24 ′ and the crank pulley 18.
It is driven in conjunction with.

Next, in the conceptual configuration diagram of FIG. 5, the diesel engine 10 for a vehicle is an exhaust manifold 2.
8 and an intake passage 34 including an intake manifold 32. In addition, an exhaust gas recirculation passage 36 (hereinafter, sometimes referred to as an EGR passage) having an upstream end communicating with a proper position of the exhaust passage 30 and a downstream end communicating with a proper position of the intake passage 34 is provided. The EGR passage 36 is provided with an EGR cooler generally designated by reference numeral 16 and a variable opening EGR valve 38 for controlling the flow rate of recirculated exhaust gas downstream of the EGR cooler 16 in the EGR passage 36. Is interposed.

[0009] The EGR valve 38, the load sensor of the temperature signal _{T w,} the engine 10 of the temperature sensor 42 for detecting the cooling water temperature of the speed signal _{N e,} the engine 10 of the rotational speed sensor 40 for detecting the rotational speed of the engine 10 load signal L _e which is detected by _44, the intake pressure signal P _b of the intake pressure sensor 46 for detecting the intake pressure in the intake passage _34, other engine 1
The control unit 48 receives a signal indicating the operating state of 0, sets an appropriate amount of EGR gas supplied to the engine 10, and sets a valve opening according to the EGR gas amount.

The EGR cooler 16 includes a heat exchange core member 52 (hereinafter simply referred to as a core member) which is driven to rotate at a slow speed around a rotation axis OO by an electric motor 50 having a variable speed. A housing 54 is housed therein, and the EGR passage 36 and the cooling air passage 56 communicate with the housing 54. The general structure of the core member 52 is mainly composed of a large number of passages 58 in the core having a square cross section and divided by vertical and horizontal partition walls and formed in parallel to the rotation axis OO, mainly for convenience in ceramics molding technology. FIG. 7).
As an example, the thickness of the vertical and horizontal partition walls is 0.1 mm, and one side of the square cross section is about 0.8 to 1.2 mm.

A controlled amount of cooling air is supplied to the cooling air passage 56 by a blower 62 composed of a fan or a blower driven by a variable speed electric motor 60, and the cooling air passing through the EGR cooler 16 is supplied to the cooling air passage 56. It is discharged to the exhaust passage 30 or discharged to the outside air as shown by a dashed line in the figure. Note that, as indicated by arrows in the figure, the EGR gas and the cooling air
It is preferable to flow in the R cooler 16 in the opposite direction, that is, in the countercurrent.

In the cooling air passage 56 on the upstream side of the EGR cooler 16, there is provided a pressure detecting device 64 constituting clogging detecting means for detecting the clogging of the core member 52. When the clogging of the core member 52 exceeds a set state (for example, a state in which the total cross-sectional area of the exhaust gas and the cooling air passage in the core member 52, that is, the passage 52 in the core is closed by 20%), An increase in the inlet-side cooling air pressure resulting from the increase in the resistance is detected, and a clogging signal or information is supplied to the control unit 48.

According to the map built in the control unit 48, the variable speed electric motors 50 and 6 are excluded except for the operating state of the engine 10 in which EGR is not performed.
0, in the normal state where the eye of the core member 52 clogging does not reach the set state, the rotational speed signal N _e of the rotational speed sensor 40 of the engine _10, the engine load detected by the load sensor 44 L _e, EGR valve 38 The motor is driven by the control unit 48 at a rotational speed controlled in accordance with the operating conditions of the engine such as the opening degree of the engine. At this time, the rotation speed of the core member 52 around the rotation axis OO is a normal rotation speed, for example, 3
It is around 0 rpm.

The detailed structure of the EGR cooler 16 is shown in a plan view in which essential parts in FIG. 6 are cut away and a cross-sectional view in FIG. As best shown in FIG.
The housing 54 of the cooler 16 has a first housing member 5 having an open end for receiving the core member 52 therein.
4a, and a second housing member 54b forming a lid member fastened by a V-shaped annular clamp 66 to the open end of the first housing member 54a, the opposite side of the open end of the first housing member 54a. Is formed integrally with an inlet end member 36a of the EGR passage 36 and an outlet end member 56b of the cooling air passage 56. Similarly, the EGR passage 36 is formed in the second housing member 54b. The outlet side end member 36b and the inlet side end member 56a of the cooling air passage 56 are integrally formed.

The core member 52 is a ceramic mat 7 which functions as a cylindrical heat insulating and sealing member formed by compacting heat insulating refractory fibers made of silica, alumina or the like.
0 through an outer cylinder 7 made of a metal material, for example, a stainless steel plate.
2, the outer cylinder 72 is provided on the inner surface of the first housing member 54a at equal intervals in the circumferential direction in two planes perpendicular to the rotation axis OO. Each of the three supporting rollers or wheels 74 is supported so as to be freely rotatable around the rotation axis OO.

An annular sprocket wheel 76 is fixed to the outer surface of the outer cylinder 72 by appropriate means such as welding press fitting, and the sprocket wheel 76 is operatively connected to a sprocket pinion 80 via a chain 78. . The sprocket pinion 80 is fixed to the output shaft 82 of the variable-speed electric motor 50. Therefore, by controlling the rotation speed of the electric motor 50 by the control unit 48, the outer cylinder 72 containing the core member 52 is desired. Can be rotated at a speed of The sprocket pinion 80 is a pin pinion provided with a pin that meshes with a sprocket tooth.
0 can be changed so that the sprocket wheel 76 is rotated by directly meshing the sprocket wheel 76 with the sprocket wheel 76.

A first seal member 84 is pressed against the end face of the core member 52 facing the cooling air inlet end member 56a and the exhaust gas outlet end member 36b by a leaf spring 86. Similarly, the cooling of the core member 52 is performed. Air outlet side end member 56b
And on the end face opposing the exhaust gas inlet side end member 36a,
The second seal member 88 is pressed by a leaf spring 90.

The first and second seal members 84 and 88
Have substantially the same shape and are each made of a copper-based, carbon-based, fluoride-based or oxide-based solid lubricant, particularly preferably aluminum bronze. The first and second seal members 84 and 88 made of aluminum bronze have a sufficiently low coefficient of friction at a high temperature, do not damage the end surface of the core member 52 to be slid, and can be cast. Molding of various shapes is easy.

FIG. 7 shows the front shape of the first seal member 84. The seal member 84 has a Θ-shaped front shape including an annular outer frame portion 84a abutting on the outer peripheral edge of the end surface of the core member 52 and a diametrical bridge portion 84b.
A substantially semicircular through hole above 4b is the exhaust gas outlet side end member 3.
6b communicates with the substantially semicircular opening end and a number of in-core passages 58 in opposing substantially semicircular portions of the core member 52, and the substantially semicircular through-hole below the bridging portion 84b provides cooling. The substantially semicircular opening end of the air inlet side end member 56a communicates with a large number of core passages 58 in the opposing substantially semicircular portions of the core member 52. As described above, the second seal member 88 also has a similar Θ-shaped front shape, and its bridging portion 88b
Exhaust gas inlet side end member 3 through a substantially semicircular through hole above
A substantially semicircular opening end of the core member 52 communicates with a number of in-core passages 58 in opposing substantially semicircular portions of the core member 52, and a substantially semicircular through hole below the bridging portion 88b provides cooling. The substantially semicircular opening end of the air outlet side end member 56b communicates with a number of in-core passages 58 in opposing substantially semicircular portions of the core member 52. Although not shown in the drawings, the rotation of the core member 52 about the rotation axis O-O causes the first member to rotate.
The first and second seal members 84 and 88 are fixed to the second housing member 5 by a detent pin or other appropriate means so that the second seal members 84 and 88 do not rotate.
4b and the first housing member 54a are respectively locked in the rotation direction.

In the above configuration, during operation of the engine 10, part of the exhaust gas discharged into the exhaust passage is controlled by the control unit 48 according to the operation state of the engine 10.
The flow rate is controlled by an EGR valve 38 whose opening degree is controlled by the EGR valve 38 and flows through the EGR passage 36. On the other hand, the core member 5
While the clogging of the second core passage 58 does not reach the set state, the variable-speed electric motors 50 and 60 are driven at the rotation speed controlled by the control unit 48, respectively, according to the operating state of the engine. The electric motor 50
Causes the core member 52 to rotate around the axis of rotation O-O at a controlled speed, for example, around 30 rpm, via the sprocket pinion 80, the cooperating chain 78, and the sprocket wheel 76. A fan or blower 62 is driven by the electric motor 60, and a cooling air having a flow rate necessary for cooling the EGR gas flowing in the EGR passage 36 to a desired temperature is supplied to the core member 52.
Supplied to

By the rotation of the core member 52, cooling air flows through almost half of the passages 58 having a small cross section to cool the partition walls of the passages 58 in the core. On the other hand, the remaining approximately half of the core passages 58 are provided with EGR from the EGR passage 36.
Since the gas flows, the high-temperature EGR gas is cooled in contact with the partition wall, and then supplied to the intake passage 34 of the engine 10, mixed with the intake air and supplied to the combustion chamber of each cylinder of the engine 10. Since the cooled EGR gas is supplied to the combustion chamber of the engine together with the intake air, improved volumetric efficiency, improved output and fuel consumption of the engine 10, also improves exhaust emissions such as NO _x.

In the above proposed EGR cooler 16, it is necessary to provide a variable speed electric motor 50 in order to rotate the core member 52 at a slow speed around the rotation axis OO. Fan or blower 62
Requires a variable speed electric motor 60 for driving the motor. Therefore, the manufacturing cost is considerably high, and since these electric motors 50 and 60 are driven as an electric load of the alternator 22 driven by the engine 10, a large-capacity alternator 22 is required.
Since a considerable portion of the output of 0 is consumed by the electric motors 50 and 60, there is a problem that fuel efficiency is deteriorated.

In addition, as is apparent from the side view showing the mounted state of the EGR cooler 16 in FIG.
Since the 0 and 60 protrude largely to the side of the cylinder head 14, the electric motor 50 and the other motor parts, which are not shown, avoid interference with other engine parts, auxiliary machines, and vehicle parts around the engine. There is a problem that it is not easy to secure a space for disposing the 60, and the mountability is poor.

[0024]

SUMMARY OF THE INVENTION The present invention relates to an EGR cooler, that is, a passage having a small cross-sectional area formed in a plurality of core members having a honeycomb structure while rotating the core member having a honeycomb structure at a slow speed. In order to improve the above-described various problems in the EGR cooler in which the exhaust gas is cooled and supplied to each cylinder of the engine together with the intake air by alternately circulating the exhaust gas and the cooling air, Eliminate the electric motor for driving the fan such as a fan or blower as an air supply source, and if necessary, eliminate the electric motor for driving the core member, thereby reducing the electric load on the engine and improving fuel efficiency, At least, by eliminating the electric motor for driving the blower which requires a considerable arrangement space, the mountability of the EGR cooler to the engine can be improved. To provide an inexpensive exhaust gas recirculation cooler which can, mainly aims.

[0025]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a rotatable exhaust passage and a cooling air passage for recirculating a part of exhaust gas of an engine together with intake air into a cylinder of the engine. A heat-exchange core member having a small-diameter cross-sectional area inside the core and having a small cross-sectional area for allowing the recirculated exhaust gas and the cooling air to flow therethrough; A core member driving device that rotates around the rotation axis, a rotary blower such as a fan or a blower that supplies cooling air to the cooling air passage, and the blower includes a pulley mounted on a drive shaft thereof and the engine. It is configured to be driven by a belt wound around a crank pulley mounted on a crankshaft or a driving pulley of another accessory linked to the crankshaft. It proposes a recirculated exhaust gas cooler, characterized and.

According to the configuration of the present invention, a relatively large electric motor for driving a rotary type blower such as a fan or a blower which operates as a cooling air source for cooling EGR gas is not required, so that the electric load of the engine can be reduced. As a result, the output and the fuel efficiency are improved, the capacity of the alternator can be reduced, and the mountability of the EGR cooler on the engine is improved.

In the present invention, it is preferable that a first clutch device for power connection / disconnection is provided on the drive shaft of the blower. By providing the first clutch device, E
Since the operation of the blower can be temporarily stopped when the engine is not operated in the GR and the clogging of the core member described later is performed, the waste of the engine output can be prevented, and the fuel efficiency of the engine can be improved. As will be described in detail later, it is possible to smoothly eliminate clogging of the core member.

In the present invention, the core member driving device may further include a transmission means operatively connected to a drive shaft portion between the blower pulley fixed to the blower drive shaft and the first clutch device. It is preferable to be configured to be decelerated and driven. With this configuration, the electric motor conventionally used as a drive device for rotating the core member around its rotation axis can be omitted, so that the electric load of the engine can be further reduced, and the EG can be further reduced.
The mountability of the R cooler on the engine can be improved.

Further, in the present invention, it is preferable that a second clutch device capable of connecting and disconnecting the transmission of power to the core member driving device or reducing the transmitted power is provided in the transmission means. By providing the second clutch device, the operation of the core member driving device can be temporarily stopped in the operating region of the engine in which EGR is not performed, and when the core member described later is clogged. Waste can be prevented, the fuel efficiency of the engine can be improved, and clogging of the core member can be quickly and easily achieved.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS. (Note that FIG.
In the proposed EGR cooler and the engine equipped with the EGR cooler described with reference to FIG. 7, substantially the same or corresponding members and portions are denoted by the same reference numerals. First, in the schematic side view of FIG. 1 and the schematic front view of FIG.
The GR cooler 16 has its core member 52 connected to the rotation axis OO.
Except for the electric motor 50 that rotates around the motor and the electric motor 60 that drives a rotary blower 62 such as a fan or blower as a cooling air source.
Has substantially the same structure as

As best shown in FIGS. 1 and 2,
The common belt 2 extends over the crank pulley 18 fixed to the crankshaft 20, the driving pulley 24 'of the cooling fan 24, and the driving pulley 22' of the alternator 22.
6 is wound, and the alternator 22 and the cooling fan 24 are driven in conjunction with the crankshaft 20 of the engine 10 in the same manner as in the engine 10 equipped with the EGR cooler 16 already proposed. A drive pulley 92 for a one-stage blower is additionally provided coaxially with the drive pulley 24 '.

On the other hand, the cooling air passage 5 of the EGR cooler 16
As shown in FIG. 3, a blower 62 for supplying cooling air to the rotor 6 is housed in a hollow disk-shaped housing 94 and has a rotor 98 having a number of radially projecting blades 96 on its outer periphery. It has. The rotor 98 is connected to a blower drive shaft or a first drive shaft 102 via a bearing 100.
The first drive shaft 102 is rotatably supported at one end, and a blower pulley 104 is fixed to the other end of the first drive shaft 102. A first clutch device 106 for power connection and disconnection is interposed between the rotor 98 and the first drive shaft 102. The first clutch device 106 is attached to a hub 98 ′ of the rotor 98 by a leaf spring 108.
A ring-shaped armature 110 connected through
The clutch body 114 is fixed to the drive shaft 102 and has an annular electromagnetic coil 112 on the outer periphery thereof. The electromagnetic coil 112 is controlled by the control unit 48.
Urges the armature 110 to abut against the clutch body 114 to cause the first drive shaft 102 and the rotor 9
When the control unit 48 is deenergized, the armature 110 is separated from the clutch body 114 by the leaf spring 108, and the connection between the first drive shaft 102 and the rotor 98 is released.

Pulley 1 for blower of first drive shaft 102
A first worm 116 is fixed to an intermediate portion between the first drive device 102 and the first clutch device 106, and the first worm 116 is attached to one end of an intermediate shaft 118 that is disposed to extend in a direction perpendicular to the first drive shaft 102. First worm wheel 1 fixed
Engage with 20. A second worm 122 is fixed to the other end of the intermediate shaft 118, and the second worm 122 is
It meshes with the second worm wheel 126 fixed to one end of the drive shaft 124. As shown in FIG. 3, the second drive shaft 124 is disposed substantially parallel to the first drive shaft 102.

A second clutch device 128 is provided at the other end of the second drive shaft 124. The second clutch device 128 is a well-known fluid clutch device. For example, the principle structure of the second clutch device 128 will be described with reference to FIG. 3, and a disc-shaped rotor 130 fixed to the second drive shaft 124 will be described.
And a hollow disk-shaped housing 134 rotatably supported on a second drive shaft 124 via a bearing 132, and a sprocket pinion 80 is fixed to an outer surface of the housing 134. Same sprocket pinion 8
No. 0 drives the core member 52 via a chain 78 wound around a sprocket wheel 76 fixed to the outer periphery of the outer cylinder 72 of the EGR cooler 16 and the sprocket pinion 80. In other words, the sprocket pinion 80, the sprocket wheel 76 and the chain 7
8 forms a core member driving device.

Inside the housing 134, a disk 136 is disposed coaxially with the second drive shaft 124 so as to face the rotor 130.
Is supported by a housing 134 via a spline 138 so as to be slidable in the axial direction and relatively non-rotatable in the rotational direction. The hollow chamber 1 inside the housing 134
The inside of 40 is filled with a heat-resistant high-viscosity liquid, for example, silicone oil.

A large number of annular projections 1 are formed on the outer peripheral portion in the radial direction on the side of the rotor 130 facing the disk 136.
42 are formed at appropriate radial intervals, and a large number of annular projections 144 that can enter between the annular projections 142 are formed on the side of the disk 136 facing the rotor 130. Further, the disk 136
Is connected to an output rod 148 of an actuator 146 having an appropriate variable stroke capable of displacing the disk 136 in the axial direction.
Is supported by the housing 134, and the displacement position of the output rod 148 in the axial direction is controlled by the control unit 48.

When the disk 136 is at the position shown by the solid line in FIG. 3, the annular projection 142 of the rotor 130 and the annular projection 144 of the disk 136 are sufficiently separated in the axial direction, so that the second drive shaft 124 rotates and the rotor 1
Even if 30 rotates within hollow chamber 140, sufficient torque is not transmitted to disk 136 via silicon oil, and sprocket pinion 80 and sprocket wheel 76
Since the torque that overcomes the frictional resistance in the core member driving device composed of the core member 52 and the various frictional resistances associated with the rotation of the outer cylinder 72 containing the core member 52 is not transmitted, the core member 52 does not rotate.

When the actuator 146 is operated by the control signal of the control unit 48 to move the disk 136 toward the rotor 130 via the output rod 148, the annular projection 144 of the disk 136 is placed between the annular projections 142 of the rotor 130. Enters into a labyrinth passage-shaped narrow space, and the disk 136
Torque is increased, the housing 134 rotates via splines 138 at a speed commensurate with the increase in transmitted torque, and the sprocket wheel 76 rotates via the sprocket pinion 80 and the chain 78, thus rotating the core member 52. You. When the disk 136 moves rightward to the maximum displacement position shown by the dotted line in FIG.
The annular projection 144 cooperating between them penetrates the deepest to transmit the maximum torque, and the rotational speed of the core member 52 increases.

As shown in FIG. 2, a belt 150 is wound between the blower pulley 104 fixed to the first drive shaft 102 and the drive pulley 92. Note that in FIG.
This is a tension roller having a well-known structure that abuts the belt to tension the belt.

In the normal operating state where the operating state of the engine 10 is a state where EGR is performed and the passage 58 in the core of the core member 52 is not clogged, the crankshaft 20
Rotation of the crank pulley 18 and the alternator pulley 2
The power is transmitted to the alternator pulley 22 'via a belt 26 wound around the fan pulley 2' and the fan pulley 24 ', and further from a drive pulley 92 provided coaxially to the alternator pulley 22' via a belt 150. And transmitted to the blower pulley 104.

In the normal engine operation state, the first clutch device 106 is engaged by the drive signal of the control unit 48, and the second clutch device 128 is maintained in the maximum torque transmission state substantially close to the direct connection. Therefore, the blower 62 is driven at the rotation speed of the first drive shaft 102 which is higher than the rotation speed of the crankshaft 20 in accordance with the pulley ratio between the crank pulley 18 and the pulley 104 for the blower, and the pressurized cooling air is Is supplied to the core member 52 in the same manner as in the proposed EGR cooler. The first drive shaft 102
The rotation of the first worm 116 and the first worm wheel 120 composed of the first worm wheel 120 and the second worm 12
2 and a second worm wheel 126, a second drive shaft 124, a second clutch device 128
The transmission is transmitted to the sprocket pinion 80 after being greatly decelerated via transmission means including the following. The rotation of the sprocket pinion 80 is transmitted to the core member 52 via a chain 78 and a sprocket wheel 76, and the core member 52
Rotate at a slow speed, for example, about 30 rpm.

The EGR gas supplied to the core member 52 is cooled by heat exchange with the cooling air supplied from the blower 62 in substantially the same manner as the EGR cooler proposed above. is supplied to the intake passage 34 of the engine 10 via the EGR valve 38, the output by improving the volumetric efficiency of the engine 10, the fuel economy is improved, NO _x in the exhaust gas is reduced.

Next, when the engine 10 enters an operating state in which EGR is not performed, the signal of the control unit 48 releases the first clutch device 106, so that the operation of the blower 62 is stopped and Since the two-clutch device 128 is also set to substantially not transmit torque, the rotation of the core member 52 about the rotation axis OO is stopped, and the EGR valve 38 is fully closed.
The EGR cooler 16 enters a rest state.

An increase in the operating time of the engine 10 and therefore E
As the operating time of the GR cooler 16 is accumulated, moisture and unburned fuel in the exhaust gas are liquefied and adhere to the partition wall of the core passage 58 of the core member 52, and soot and other solid particles adhere thereto. And so-called clogging occurs. When clogging occurs and the cross-sectional area of the core passage 58 decreases,
The amount of cooling air flowing through the cooling air passage 56 decreases and the EGR
As the gas cooling performance decreases, the flow rate of the EGR gas also decreases.

Therefore, in a state where the clogging of the core member 52 is set in advance, for example, the total cross-sectional area of the core passage 58 facing the cooling air passage 56 is 20% of the initial cross-sectional area.
If it has decreased, it is necessary to remove clogging deposits in the passage 58 in the core and perform so-called cleaning. The passage 58 in the core
When the clogging of the core member 52 progresses, the cooling
Of the cooling air passage 56 in the upstream of the EGR cooler in various clogged states is experimentally examined in advance, so that the discharge of the blower 62 The control unit 48 determines whether or not the clogging has exceeded the set state based on the output signal of the pressure detecting device 64 provided on the side.
Is determined.

When the clogging of the core member 52 exceeds the set state, the control unit 48 sends the first clutch device 1
06 and the second clutch device 128 are supplied with control signals, respectively, and the first clutch device 106 is released for a preset time, so that the blower 62 stops for the set time. Also,
The second clutch device 128 is in a state in which substantially no torque is transmitted or a torque that is significantly smaller than that during normal operation is generated for a set time, so that the sprocket pinion 80 does not rotate or at a significantly lower speed. The core member 52 stops rotating, or rotates at a low speed of 5 to 10 rpm, for example. On the other hand, the EGR valve 3
8 is maintained at an opening corresponding to the operating state of the engine 10 at that time.

Since the core member 52 stops or rotates at a low speed and the supply of the cooling air is stopped, the temperature of the core member 52 rises in a short time (for example, several seconds) due to the high temperature of the EGR gas. Due to the temperature rise of the core member 52,
Moisture and liquefied unburned fuel that have functioned as a binder for the deposits in the core passage 58 are vaporized and lose their function as a binder, so that particulate deposits such as soot do not lose their binding force or bind. Becomes significantly smaller and can be easily removed.

After the elapse of the set time, a drive signal is sent from the control unit 48 to the first clutch device 106 and the second clutch device 128, and the core member 5
2 returns to the normal rotation speed, and the blower 62
When the cooling air is supplied to the core member 52 from the core, the deposits in the core passage 58 are mostly blown off by the cooling air flow and discharged to the exhaust passage 30 (or discharged to the outside air together with the cooling air flow). A portion is blown off by the EGR gas and flows into the intake passage 34. As a result, clogging of the core member 52 is effectively eliminated, or at least greatly reduced from the set state. As a result, the cooling of the EGR gas is effectively performed, and the required flow rate of the EGR gas can be secured.

In the above device, the pressure detecting device 64 is provided as a means for detecting clogging of the core member 52 on the upstream side of the EGR cooler 16 in the cooling air passage 56, but the upstream side of the EGR cooler 16 is provided. Pressure sensing devices are provided in both the cooling air passage 56 on the downstream side and
The clogging state can be detected by detecting the pressure loss of the cooling air flowing through the GR cooler 16 as a differential pressure. Similarly, as a means for detecting clogging of the core member 52, E
By providing pressure detection devices on the upstream and downstream sides of the EGR cooler 16 in the GR passage 36, the pressure loss of the EGR gas flowing through the EGR cooler 16 can be detected as a differential pressure.

According to the embodiment of the present invention, the driving device of the rotary blower 62 for supplying the cooling air to the core member 52 is linked to the crankshaft 20 of the engine 10 without using a conventional electric motor. A belt 150 wound around a drive pulley 92 additionally provided to a pulley 22 ′ of the alternator 22, which is one of the accessories, and a blower pulley 104 fixed to a first drive shaft 102 that drives the blower 62.
, The output of the engine 10 and the fuel consumption can be improved, the alternator 22 can be downsized, and the EGR cooler 16
There is an advantage that the mountability on the engine 10 can be improved. In addition, if possible in the arrangement space, a pulley corresponding to the drive pulley 92 may be added to the crank pulley 18 to transmit the belt of the blower pulley 104,
The drive pulley 92 is used as an auxiliary device other than the alternator 22, such as a pulley for driving a fuel injection pump, a pulley for driving a camshaft for a valve train, or another pulley driven in conjunction with the crankshaft 20. With pulley 1 for blower
04 can be transmitted by a belt, and in the case of these modifications, the same effects as described above can be obtained.

Further, an electric motor for rotating the core member 52 is eliminated, and a transmission means including a second drive shaft 124 operatively connected to the first drive shaft 102 for driving the blower 62 and driven to reduce the speed is provided. By driving the core member 52, the electric load of the engine 10 can be further reduced, the output and the fuel consumption of the engine 10 can be improved, and the alternator 22 can be further downsized. There is an advantage that the mountability can be improved.

Further, a first clutch device for power connection / disconnection is interposed on the drive shaft of the blower, and power transmission / disconnection or power transmission is reduced in the transmission means of the core member drive device. With the provision of the second clutch device, the EGR cooler 16 is stopped in the operating region of the engine 10 where EGR is not performed, and the core member 52
When clogging occurs, there is an advantage that cleaning for eliminating or at least reducing clogging can be easily performed.

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with appropriate changes or modifications within the scope of the claims of the present invention. As an example, as the driving device for the core member, a gear transmission or a belt transmission can be appropriately used instead of the illustrated sprocket transmission. Also, an electromagnetic clutch device can be used instead of the fluid clutch device exemplified as the second clutch device 128, and similarly, as the first clutch device 106, for example, a friction plate clutch operated by a fluid actuator A device can be employed.

[0054]

As described above, the recirculation exhaust gas cooling apparatus according to the present invention is provided with an exhaust gas recirculation passage and a cooling air passage for recirculating a part of the exhaust gas of the engine together with the intake air into the cylinder of the engine. A heat exchange core member rotatably interposed therein and having a plurality of passages in the core having a small cross-sectional area through which a large number of holes are provided substantially parallel to the rotation axis and through which the recirculated exhaust gas and the cooling air flow. A core member driving device that rotates the core member around the rotation axis, a rotary blower such as a fan or a blower that supplies cooling air to the cooling air passage, and a pulley mounted on the drive shaft of the blower. The engine is configured to be driven by a belt wound around a crank pulley mounted on a crankshaft of the engine or a driving pulley of another auxiliary machine interlocked with the crankshaft. By not using an inefficient electric motor for driving the blower, but driving the blower directly by the output of the engine, the electric load on the engine can be reduced, and the output and fuel efficiency can be improved. In addition, the size of the alternator can be reduced, and the mountability of the EGR cooler to the engine can be improved.

In the present invention, the core member driving device may further include a transmission means operatively connected to a drive shaft portion between the blower pulley fixed to the blower drive shaft and the first clutch device. By using a configuration in which the motor is decelerated, the electric motor conventionally used as a core member driving device can be added and eliminated, and the electric load of the engine can be further reduced to improve the output and the fuel efficiency. And the mountability of the EGR cooler on the engine can be further improved.

Further, in the present invention, a first clutch device for power connection / disconnection is provided on the drive shaft of the blower, and the transmission of power to the core member drive device is interrupted in the transmission means. By providing the second clutch device that can reduce the contact or transmission power,
EG in an engine operating state where EGR is not performed
The operation of the R cooler and the blower can be stopped, and when the core member is clogged, the operation of the blower is temporarily stopped, and the driving of the core member is temporarily stopped, or the speed is extremely low. There is an advantage that clogging can be eliminated or at least reduced.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a preferred embodiment of the present invention.

FIG. 2 is a front view of an engine equipped with the EGR cooler shown in FIG.

FIG. 3 is a schematic configuration diagram of a blower and a core member driving device in the engine equipped with an EGR cooler shown in FIG. 1;

FIG. 4 is a schematic side view of a proposed engine equipped with an EGR cooler.

FIG. 5 is a conceptual configuration diagram illustrating an operation mode of an EGR cooler in the engine shown in FIG.

FIG. 6 is an enlarged plan view showing a cross section of a main part of the EGR cooler 16 in FIG.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Diesel engine for vehicles, 12 ... Crank case, 14 ... Cylinder head, 16 ... EGR cooler, 18
... Crank pulley, 20 ... Crank shaft, 22 ... Alternator, 22 '... Alternator driving pulley, 24 ... Cooling fan, 24' ... Cooling fan driving pulley, 26 ... Belt, 30 ... Exhaust passage, 34 ... Intake passage,
36: exhaust gas recirculation passage (EGR passage), 38: EGR
Valve, 48: control unit, 50: electric motor,
52: heat exchange core member, 56: cooling air passage, 58: passage in the core, 60: electric motor, 62: blower, 76: sprocket wheel, 78: chain, 80: sprocket pinion, 92: drive pulley, 94: blower Housing 96, blades 98, rotor 102, first drive shaft (blower drive shaft) 104, pulley for blower 106
... first clutch device, 116 ... first worm, 120 ...
First worm wheel, 122... Second worm, 124
... Second drive shaft, 126 ... Second worm wheel, 128
... second clutch device, 150 ... belt.

Claims (4)

[Claims] An exhaust gas recirculation passage for recirculating a part of exhaust gas of an engine together with intake air into a cylinder of the engine and a cooling air passage are rotatably interposed therein, and are substantially parallel to a rotation axis therein. A heat-exchange core member having a small cross-sectional area inside the core and having a small cross-sectional area for allowing the recirculated exhaust gas and the cooling air to flow therethrough; a core-member driving device for rotating the heat-exchange core member around the rotation axis; A rotary blower such as a fan or blower that supplies cooling air to the cooling air passage, and the blower is interlocked with a pulley mounted on its drive shaft and a crank pulley mounted on the crankshaft of the engine or the crankshaft. A recirculation exhaust gas cooling device characterized by being driven by a belt wound around a driving pulley of another accessory. 2. A first connecting / disconnecting power supply for the drive shaft of the blower.
The recirculation exhaust gas cooling device according to claim 1, wherein the clutch device is interposed. 3. The deceleration drive via a transmission means operatively connected to a drive shaft portion between a blower pulley fixed to the blower drive shaft and the first clutch device, wherein the core member drive device is driven. The recirculation exhaust gas cooling device according to claim 1 or 2, wherein the exhaust gas is cooled. 4. The power transmission device according to claim 3, wherein a second clutch device capable of connecting / disconnecting power transmission to the core member driving device or reducing transmission power is provided in the transmission means. Recirculation exhaust gas cooling device.