JP2003267064A - Heat radiation structure for heat source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiation structure for a heat source, lightening the load of a cooler for the heat source such as an engine. <P>SOLUTION: The heat radiation structure comprises the heat source 4 generating noises, a heat source cover 8 covering at least part of the heat source 4 at a space from the heat source 4, an aluminum sound absorbing material 10 mounted on the heat source cover 8 at the side of the heat source 4, and a ceramic layer Ce formed on the surface of the aluminum sound absorbing material 10 on the side of the heat source cover 8. The ceramic layer Ce is formed by applying a liquid ceramic thereto. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat radiation structure for a heat source.

[0002]

2. Description of the Related Art In work vehicles such as hydraulic excavators,
Work is performed by driving a work machine or the like by a hydraulic drive circuit that uses an engine as a drive source. Since the engine emits heat and noise, in order to reduce the noise around the work site, the engine is covered with a cover to form an engine room, and a noise absorbing material is provided in the engine room to reduce the noise. The heat balance of the engine is ensured by installing a cooling system such as an oil cooler and intake and exhaust ports.

FIG. 7 is a schematic view of the inside of the engine room of a conventional hydraulic excavator as seen from the rear. As shown in FIG. 7, the engine room 1 of the hydraulic excavator accommodates a radiator 2, a fan 3, an engine 4 and a hydraulic pump 5 in this order. Then, on the upper surface of the engine cover 8 that covers the engine room 1, an intake port 8a that communicates the space in front of the radiator 2 (on the left side in FIG. 7) with the outside air, and the space behind the radiator 2 (on the right side in FIG. 7) and the outside air. Exhaust port 8 communicating
and b. A urethane-based sound absorbing material 30 having excellent sound absorbing performance is attached to the inner surface of the engine cover 8. In FIG. 7, 6 is an oil cooler for cooling the operating oil, which is installed in parallel with the radiator 2, and 7 is an engine 4
Is a muffler that is arranged in parallel to discharge exhaust gas to the outside of the engine room 1 via the tail pipe 7a.

The cooling air, which has flowed into the engine room 1 from the intake port 8a by the rotation of the fan 3, exchanges heat with the radiator 2 and then passes through the fan 3, and the engine 4 and the hydraulic pump 5 in the space behind the radiator 2 and the like. The heat is absorbed from the equipment and is discharged to the outside of the engine room 1 through the exhaust port 8b. The engine cooling water cooled by the radiator 2 is guided to the engine 4, cools the engine 4, and returns to the radiator 2. With this cooling system, the engine 4 does not overheat and the proper heat balance is maintained. Also,
Noise generated by the engine 4, the fan 3, the hydraulic pump 5, and the like is reduced by the sound absorbing material 30.

[0005]

However, the above-mentioned prior art has the following problems. That is, as an approach to environmental problems in recent years, demands for noise reduction of construction machinery have increased, and exhaust gas regulations have become more stringent in order to seriously improve air pollution, especially in metropolitan areas. An EGR (exhaust gas recirculation) device is widely known and has begun to be used as an effective means for the exhaust gas regulation.

The EGR device lowers the oxygen concentration in the intake air by recirculating a part of the exhaust gas discharged from the combustion chamber from the exhaust passage to the intake passage, mixing it with the intake air, and sending it back into the combustion chamber. It has the effect of lowering the combustion temperature, and has a great effect of suppressing the generation of harmful substances contained in exhaust gas, particularly nitrogen oxides (NOx). In this case, if the high-temperature exhaust gas recirculation gas is sent to the intake passage as it is, there are disadvantages such that the intake air temperature rises and the output decreases, and the performance and durability of the EGR valve that controls the flow rate of the exhaust gas recirculation are impaired. In order to avoid this, an EGR cooler in which the engine cooling water circulates is provided on the upstream side of the EGR valve, and heat is taken from the exhaust gas recirculation gas using the engine cooling water to cool the exhaust gas recirculation gas.

The exhaust gas regulation value, which will become stricter in the future, becomes E
When trying to clear by adopting the GR device, the EGR cooler will process part of the heat that was originally released to the outside from the muffler 7 together with the exhaust gas.
Due to the heat exchange in the R cooler, the temperature of the engine cooling water rises, and it becomes difficult to secure the heat balance of the engine 4. That is, it is necessary to improve the current cooling capacity of the cooling system by, for example, about 20%.

Since the urethane type sound absorbing material 30 attached to the inner surface of the engine cover 8 is a member exhibiting a heat insulating effect, there is no effect of releasing heat from this portion to the outside. Therefore, in order to improve the cooling capacity, it is conceivable to increase the outer diameter size of the fan 3 or increase the rotation speed of the fan 3, but the device becomes large and the noise from the fan 3 becomes large. Further, in order to improve the cooling capacity, it is conceivable to adopt a large size radiator or a finer fin pitch as the radiator 2, but this leads to an increase in the size of the device and a cost increase. In particular, an increase in the size of the device causes an increase in the size of the engine room 1, which is inconvenient for a hydraulic excavator with a small rearward turn, which limits the size of the engine room.

That is, if the above measures are adopted in order to cope with noise reduction and exhaust gas regulation, it is difficult to maintain the heat balance of the engine 4.

The present invention has been made in view of the above problems, and an object thereof is to provide a heat radiation structure for a heat source which can reduce the load on the cooling device for the heat source such as an engine.

[0011]

In order to achieve the above object, a heat source that emits noise and a heat source cover that covers at least a part of the heat source with a space between the heat source and the heat source,
An aluminum sound absorbing material is mounted on the heat source side of the heat source cover, and a ceramic layer is formed on the surface of the aluminum sound absorbing material on the heat source cover side. The ceramic layer is formed by applying liquid ceramic. Further, the aluminum sound absorbing material is configured to be at least one of foamed aluminum and aluminum non-woven fabric.

According to the above construction, the aluminum sound absorbing material having excellent heat conductivity is mounted inside the heat source cover, and the ceramic layer is formed on the surface of the aluminum sound absorbing material on the heat source cover side. The aluminum sound absorbing material conducts heat to the ceramic layer, and the ceramic layer efficiently radiates heat and radiates it to the outside through the heat source cover. Therefore, noise is reduced, and heat generated by the heat source is radiated to reduce the load on the cooling device for the heat source. This makes it possible to reduce the size and cost of the cooling device. Further, since the ceramic layer is formed by applying liquid ceramic, it is possible to easily cope with a complicated shape.

Further, in the heat dissipation structure of the heat source, a ceramic layer is formed on at least a part of the surface of the heat source. According to the above configuration, the heat radiation from the heat source is promoted to increase the amount of heat released to the outside through the aluminum sound absorbing material, so that the burden on the heat source cooling device can be further reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described in detail below with reference to the drawings. FIG. 1 is a schematic view of the inside of an engine room 1 of a hydraulic excavator according to an embodiment of the present invention, as viewed from the rear. As shown in FIG. 1, a hydraulic excavator engine room 1 accommodates a radiator 2, a fan 3, an engine 4, and a hydraulic pump 5 in this order. An oil cooler 6 for cooling hydraulic oil is provided adjacent to the radiator 2. A muffler 7 is attached to the engine 4 as a muffler, and exhaust gas is discharged to the outside of the engine room 1 through the tail pipe 7a. Engine room 1
Is covered by the engine cover 8, and the engine cover 8
In the upper surface of the radiator 2, there is an intake port 8a which communicates the space in front of the radiator 2 (on the left side in FIG. 1) with the outside air, and the rear of the radiator 2 (in FIG. 1).
(Right side of) and an exhaust port 8b that communicates the space with the outside air.

In the engine 4, a part of the exhaust gas is returned from the exhaust passage to the intake passage and mixed with the intake air,
An EGR device 9 that reduces NOx contained in the exhaust gas is mounted. The EGR device 9 includes an EGR cooler (not shown) that cools the high-temperature exhaust gas that recirculates into the combustion chamber. Engine cooling water circulates in the EGR cooler and exchanges heat with the exhaust gas recirculation gas.

A foamed aluminum sound absorbing material 10 is attached to the inner surface of the engine cover 8. As shown in FIG. 2, a ceramic layer C is provided on one side of the plate-shaped foamed aluminum sound absorbing material 10.
e is formed, and the foamed aluminum sound absorbing material 10 is held by the brackets 21, 22, 23 so that the ceramic layer Ce faces away from the engine 4, that is, the ceramic layer Ce faces the engine cover 8. Has been done. The foamed aluminum sound absorbing material 10 is made of ceramic layer Ce.
And the engine cover 8 are held so as to form an air layer T while being separated by a predetermined distance. The ceramic layer Ce is formed by applying liquid ceramic to the foamed aluminum sound absorbing material 10 and drying it. On the surface of the engine 4 which is a heat source, the ceramic layer CeE
Are formed.

Ceramic is a substance having a high emissivity in the wavelength region of far infrared rays, that is, a substance having a good thermal emissivity, and when energy is received in some form, the energy is emitted by far infrared ray (thermal emission). Radiates secondarily according to the law of thermodynamics. Far-infrared radiation is emitted from a molecule as energy difference from the original energy level when the molecular vibration (stretching, bending, rotation) of a substance “transitions” to the lower energy level. Then, it reaches the object to be irradiated in a straight line without heating the air in the middle, and heats the object to be irradiated.

Noise generated from the engine 4, the fan 3, the hydraulic pump 5, etc. is absorbed by the foamed aluminum sound absorbing material 10 and reduced. The inner surface of the foamed aluminum sound absorbing material 10 is warmed by the temperature rise in the engine room 1 and heat radiation from the engine 4 and the hydraulic pump 5. The foamed aluminum sound absorbing material 10 is a good conductor of heat, and the heat on the inner surface side is transmitted to the outer surface side, that is, the ceramic layer Ce, is radiated as far infrared rays, is absorbed by the engine cover 8, and is radiated to the outside air. The engine cooling water whose temperature rises by cooling the engine 4 and the EGR cooler and is returned to the radiator 2 is cooled by exchanging heat with the cooling air flowing from the suction port 8a by the rotation of the fan 3 in the radiator 2. It The cooling air that has undergone heat exchange in the radiator 2 passes through the fan 3 and absorbs heat from devices such as the engine 4 and the hydraulic pump 5, and the exhaust port 8b.
Is discharged to the outside of the engine room 1.

When the EGR device 9 is mounted, a part of the heat that is originally emitted from the muffler 7 is processed in the engine room 1, so that it is necessary to improve the cooling efficiency. 1) A foamed aluminum sound absorbing material 10 having a large thermal conductivity is used as the sound absorbing material, and the heat inside the engine room 1 and the engine 4 are used.
(2) Efficiently radiate heat from the ceramic layer Ce formed on the outer surface of the sound absorbing material (3) Form a ceramic layer CeE on the engine 4 to promote heat radiation As a result, part of the heat in the engine room 1 is efficiently radiated to the outside as heat radiation from the engine cover 8, thereby reducing the load on the cooling system by the radiator 2 and the fan 3. Therefore, there is no need to increase the outer diameter size of the fan 3, and it is not necessary to increase the rotation speed of the fan 3, and it is not necessary to use a large size radiator or a fine fin pitch radiator. The heat balance of the engine 4 can be maintained. Further, since the ceramic layer Ce is formed by applying liquid ceramic and drying it, it is possible to easily cope with a complicated shape.

It is needless to say that the present invention is not limited to the above embodiment, and changes and modifications can be made within the scope of the present invention. For example, as shown in FIG. 3, the foamed aluminum sound absorbing material 10 may be attached by studs 14 and nuts 15 provided upright inside the engine cover 8. In the figure, 16 is a foamed aluminum sound absorbing material 1
A collar having a length equivalent to 0 thickness, and 17 is a washer. In addition, as shown in FIG.
The edge may be attached to the engine cover 8. At this time, the concave portion 10a may be provided in a portion other than the attaching portion on the attaching surface side of the foamed aluminum sound absorbing material 10, and the ceramic layer Ce may be formed there.

Although the foamed aluminum sound absorbing material 10 has been described as an example of the aluminum sound absorbing material, the aluminum nonwoven fabric sound absorbing material 11 may be used. That is, as shown in FIG. 5, a ceramic layer Ce is formed by impregnating one side of the aluminum nonwoven fabric sound absorbing material 11 with liquid ceramic and drying the ceramic layer Ce, and the stud 14 and the nut 15 standing upright inside the engine cover 8.
Therefore, the aluminum nonwoven fabric sound absorbing material 11 may be attached. The air layer T is formed by the spacer 18. In addition, FIG.
As shown in, the bracket 25 into which the edge of the aluminum non-woven fabric 11 can be inserted may be provided inside the engine cover 8 to mount the aluminum non-woven fabric 11. The air layer T is formed by providing the aluminum nonwoven fabric 11 with the step portion 11a.

The type of the aluminum sound absorbing material may be appropriately selected according to the mounting site. Therefore, in the same engine room, the foam aluminum sound absorbing material 10 is used in one part and the aluminum nonwoven fabric sound absorbing material 11 is used in another part. You can use it. Further, the mounting method may be other than the above-mentioned method, and may be appropriately selected.

The liquid ceramic coating method for forming the ceramic layer Ce may be appropriately selected from spray spraying, brush coating, roller coating and impregnation.

In the embodiment, the example applied to the cooling system of the engine equipped with the EGR device has been described.
It can also be applied to an engine cooling system that does not require the R device. In this case, a small-diameter fan can be adopted, or the rotation speed of the fan can be reduced, so that noise reduction can be improved. Moreover, since a small radiator or one having a coarse fin pitch can be adopted as the radiator, space saving and low cost effects can be obtained.

Although the engine 4 is taken as an example of the heat source, the hydraulic pump 5 is also a heat source. That is, liquid ceramic may be sprayed on the surface of the hydraulic pump 5 to form a ceramic layer to promote heat dissipation. Also, other hydraulic valves also generate heat and noise, but for example, this hydraulic valve is housed in a place different from the engine room, covered with a cover different from the engine cover, and inside the cover as described above. Attach an aluminum sound absorbing material with a ceramic layer,
You may comprise the heat dissipation structure which has a noise reduction effect.

Application to other than the work vehicle is also possible. For example, it goes without saying that it can be applied to equipment such as an engine generator and an engine compressor used at a construction site.

As described above, according to the present invention, the ceramic layer is formed on the heat radiation side surface of the sound absorbing material having excellent thermal conductivity, so that the heat radiation from the portion where the sound absorbing material is mounted to the outside. Since it has a structure for increasing the temperature, it is possible to reduce the load on the cooling device of the heat source such as the engine.

[Brief description of drawings]

FIG. 1 is a sectional view of an engine room according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a heat dissipation structure of an embodiment.

FIG. 3 is a cross-sectional view of a main part according to another aspect of the embodiment.

FIG. 4 is a cross-sectional view of main parts according to another aspect of the embodiment.

FIG. 5 is a cross-sectional view of essential parts according to another aspect of the embodiment.

FIG. 6 is a cross-sectional view of main parts according to another aspect of the embodiment.

FIG. 7 is a cross-sectional view of a conventional engine room.

[Explanation of symbols]

1 ... Engine room, 2 ... Radiator, 3 ... Fan, 4
… Engine (heat source), 5… hydraulic pump, 7… muffler,
8 ... Engine cover, 9 ... EGR device, 10 ... Foamed aluminum sound absorbing material, 11 ... Aluminum nonwoven fabric sound absorbing material, Ce, CeE ...
Ceramic layer, T ... Air layer.

Claims (4)

[Claims] 1. A heat source (4) that emits noise, and a heat source cover that covers at least a part of the heat source (4) with a space from the heat source (4).
(8), an aluminum sound absorbing material (10) mounted on the heat source (4) side of the heat source cover (8), and a heat source cover (8) for the aluminum sound absorbing material (10)
A heat dissipation structure for a heat source, comprising a ceramic layer (Ce) formed on the side surface. 2. The heat radiating structure for a heat source according to claim 1, wherein the ceramic layer (Ce) is formed by applying liquid ceramic. 3. The heat dissipation structure for a heat source according to claim 1, wherein the aluminum sound absorbing material is at least one of foamed aluminum (10) and aluminum nonwoven fabric (11). 4. The heat dissipation structure for a heat source according to claim 1, wherein a ceramic layer (CeE) is formed on at least a part of the surface of the heat source (4).