JP2000336694A - Cooling device for construction machine, and construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by leading in cooling air smoothly with easily machined shape, and reducing noise while ensuring the quantity of cooling air. SOLUTION: This cooling device for a construction machine has a fan 44 for creating air flow by the rotation of an impeller, and a shroud 48 provided upstream of the fan 44 to lead the air flow P into the suction side of the fan 44, and cools heat exchangers such as a radiator 45 and an oil cooler 46 as well as an engine 32 arranged in a cover 8 for covering a revolving super structure, with the air flow P created by the fan 44. The fan 44 is an axial fan provided with an almost horizontal rotating shaft 43 driven by the driving force of the engine 32, and the shroud 48 is a cylindrical shroud provided with a fixing fitting part 48a fixed to the radiator 45, and an almost cylindrical fan outer peripheral part 48b surrounding the outer peripheral side of the impeller of the fan 44 on the anti-radiator side of the fitting part 48a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a construction machine, and more particularly to a cooling device for a construction machine capable of reducing noise while securing a cooling air flow, and a construction machine provided with the cooling device.

[0002]

2. Description of the Related Art As an example of a construction machine, a hydraulic shovel is shown in FIG. FIG. 10 is a partially enlarged view of FIG. 9, and FIG. 11 is a sectional view taken along the line XI-XI in FIG.

In FIG. 9 to FIG. 11, a hydraulic excavator 100 includes a traveling body 102 having an endless track crawler 102a on the left and right, a revolving body 103 rotatably provided on the traveling body 102, and a revolving body 103. A driver's cab 104 provided on the front left side, an engine device 106 disposed horizontally on the revolving structure 103 and including an engine 105 and accessories (not shown) related to the engine 105, and a front of the revolving structure 103. And a multi-joint type front device 107 including a boom, an arm, and a bucket.

The revolving unit 103 is usually covered with a cover 108, and the engine unit 106 and the revolving unit 103
A fuel tank (not shown) placed in front of the cover 108 is disposed in a closed space inside the cover 108. In the engine device 106, in order to cool the engine 105 and the auxiliary equipment, air is introduced from an intake hole 108a provided on one side of the cover 108 by a cooling fan 109 driven by the driving force of the engine 105. To generate an air flow P, and heat exchangers 110 such as radiators and oil coolers.
And after passing through the shroud 111 on the downstream side thereof, further pass the side of the engine 105 and the auxiliary machine,
The air is exhausted to the outside through an exhaust hole 108b provided on the other side of the cover 108.

The above-mentioned shroud 111 is for preventing the backflow of the cooling air from the high pressure downstream side to the low pressure upstream side to secure the cooling air flow, and is provided near the radially outer peripheral portion of the cooling fan 109. Are located. This shroud 1
Reference numeral 11 denotes a so-called box-type shroud, and a cooling fan 10 is provided in a substantially box-shaped housing 111a.
9 has a simple structure in which a circular through hole 111b slightly larger than the outer diameter is formed, and is attached to the heat exchanger 110 at a fixing attachment portion 111c at the end of the heat exchanger 110.

[0006] The cooling fan 109 is connected to the engine 10.
An axial fan driven by the driving force of No. 5 is used, and the rotating shaft 109a is arranged in the closed space in the cover 108 so as to be substantially horizontal. Therefore, originally, it is natural from the viewpoint of a smooth air flow that the above-described intake hole 108a is provided on the side surface of the cover 108 and the air is introduced from the substantially horizontal upstream side of the fan 109. However, the engine 105 inside the cover 108
Since auxiliary equipment and the like generate noise during operation, the cover 10
If an opening is provided on the side surface of this 8, this sound will be radiated directly to the surrounding environment, causing a significant noise, which is not preferable.
Therefore, the intake hole 108a is
8A, the air flow P is introduced downward, and an exhaust hole 108b is also provided on the upper surface 108A of the cover 108 to discharge the air flow P upward.

[0007] Generally, an axial fan has a characteristic of linearly guiding an air flow from an upstream side to a downstream side.
If there is a structure serving as a flow path resistance on the upstream side or the downstream side, the flow is likely to be disturbed under the influence. In the above-described cooling fan 109 in the engine device 106, the heat exchanger 110 is provided on the upstream side, the engine 105 and the auxiliary equipment are provided on the downstream side, and the intake holes 108a and the exhaust holes 108b are provided due to the above-described circumstances. Since the intake passage and the exhaust passage have a curved shape without being provided on the side surface of the cover 108, the passage resistance is relatively large. For this reason, the air flow around the cooling fan 109 is easily disturbed, resulting in a reduction in air volume and an increase in noise.

In order to solve this problem, for example, as described in Japanese Patent Laid-Open Publication No. Hei 8-284611, a configuration using a bell mouth type shroud instead of the so-called box type shroud 111 has been proposed. I have.

FIG. 12 is a cross-sectional view from the rear side of a hydraulic shovel to which the prior art is applied, and FIG.
It is an enlarged view of middle A part. In FIGS. 12 and 13, the portions denoted by the same reference numerals as those in FIGS. 9 to 11 indicate the same portions.

Referring to FIG. 12 and FIG.
12 is an edge 1 located immediately downstream of the heat exchanger 110.
12a and a fan peripheral portion 112b further downstream of the edge portion 112a and at a position substantially corresponding to the blade 109A of the cooling fan 109, and the edge portion 112a and the fan peripheral portion 112b are integrally formed. Is formed.

The edge 112a is attached to the wall of the heat exchanger 110 so as to cover an air passage opening (not shown) formed on the wall of the heat exchanger 110 on the side of the cooling fan 109.

As shown in FIG. 13, the fan peripheral portion 112b is located at both ends and has curved portions 112b ₁ and 112b ₂ having two arc-shaped cross sections with a radius R, and two curved portions 112b ₁ and 112b. located on the _second intermediate formed by the flat portion 112b ₃ having a cross-section of the linear shape. In the fan peripheral portion 112b, the diameters at both ends of the curved surface portions 112b ₁ and 112b ₂ are narrowed and reduced as the diameters are the largest and approach the flat portion 112b ₃ .
And it is configured so that the diameter is smallest 2b _3.
Incidentally, 113 is a shroud centerline is defined so as to pass through the center position of the plane portion 112b ₃ of the fan surrounding portion 112b.

At this time, in order to prevent interference caused by vibration of the vehicle body, the shroud 112 is attached to the cooling fan 109 so as to maintain a constant space (tip clearance t) in the radial direction.

The significance of the chip clearance is as follows. That is, the blade 1 of the cooling fan 109
The flow near the tip clearance between the outer periphery of the 09A and the inner periphery of the shroud 112 is a complicated flow,
The portion near the outer periphery of the blade 109A is a region where the effect of the discharge force of the fan is strong, and the cooling air flows from the upstream to the downstream (the direction of A in FIG. 13), but the vicinity of the inner periphery of the shroud fan peripheral portion 112b is near. This is a region to which the discharge force of the fan does not reach, and flows backward from the downstream side of the high pressure to the upstream side (the direction of B in FIG. 13). The smaller the tip clearance t is, the smaller the above-mentioned backflow is, which is preferable.

However, the shroud 112 is fixed to the vehicle body via the heat exchanger 110 while the cooling fan 1
Since 09 is fixed to the engine 105, the shroud 112 and the cooling fan 109 belong to different vibration systems, and are relatively displaced from each other during operation. Therefore, the lower limit value of the chip clearance t is determined so that the shroud 112 and the cooling fan 109 do not interfere with each other due to the vibration.

[0016] Then, the news in the prior art cooling apparatus, the rotation shaft 109a width of the blade 109A L, the distance from the blade 109A end of the heat exchanger 110 side to the shroud centerline 113 as L _1, A noise measurement experiment is performed by variously changing the covering ratio α defined by α = L ₁ / L. FIG. 14 shows the result of the noise measurement experiment, and it is assumed that the optimum value with the lowest noise is obtained when α = 60%. Further, if an allowable range of +2 dB, which is a range that is difficult for human ears to identify, is taken with respect to this optimum value,
It is assumed that the optimal range of α is 41 to 70%.

[0017]

According to the above prior art, a bell mouth type shroud 112 is provided downstream of a heat exchanger 110.
Is provided to smoothly introduce the air flow P into the cooling fan 109 to reduce turbulence, and to optimize the covering ratio α of the shroud 112 to reduce noise.

However, as shown in FIG. 13, the bell mouth type shroud 112 employed in the prior art has a shape in which a flat portion and a curved portion are mixed in a complicated manner, so that processing is not easy, and productivity is low. There is a problem that it is difficult to improve. In addition, there is a problem that the production cost is increased.

An object of the present invention is to provide a cooling device for a construction machine capable of improving productivity by smoothly introducing cooling air in a shape that can be easily machined, and reducing noise while securing a cooling air volume. And construction machinery.

[0020]

(1) In order to achieve the above object, the present invention provides a fan which generates an air flow by rotation of an impeller having a number of blades, and a fan provided upstream of the fan. And a shroud for introducing the air flow to the suction side of the fan, and a heat exchanger such as a radiator, an oil cooler, and an engine disposed in a cover covering the revolving unit and an engine are cooled by the air flow generated by the fan. In the cooling device for a construction machine, the fan is an axial fan having a substantially horizontal rotation shaft driven by the driving force of the engine, and the shroud is fixed to the heat exchanger. A cylindrical shroud comprising a mounting portion and a substantially cylindrical fan outer peripheral portion surrounding an outer peripheral side of the impeller of the fan on a side opposite to the heat exchanger of the mounting portion.

When the air flow is generated by the rotation of the impeller of the fan, the air flow is introduced into the suction side of the fan through the shroud and then blown out to the blow side of the fan. Then, in this series of flows, the heat exchanger and the engine in the cover are cooled. Here, when the fan is an axial fan having a substantially horizontal rotation shaft, usually, a heat exchanger is arranged on one of the upstream side and the downstream side of the fan, and the engine is arranged relatively close to the other. Since these become flow path resistances, the air flow around the fan is easily disturbed due to the influence.

Therefore, in the present invention, by using a cylindrical shroud having a fan outer peripheral portion surrounding the outer peripheral side of the fan impeller, for example, the air flow passing through the heat exchanger is smoothly introduced into the fan, and the turbulence is generated. Can be reduced.

At this time, by forming the fan outer peripheral portion into a substantially cylindrical shape, a curved portion and a flat portion are not complicatedly mixed as in the conventional structure having a bell mouth shape, and processing is extremely difficult. It is simple and productivity can be improved. Also, for example, α ₀ = L ₁₀ / L using the width L _{0 of} the blade in the fan rotation axis direction and the distance L ₁₀ from the heat exchanger side end of the blade to the anti-heat exchanger side end of the outer periphery of the shroud fan. ₀ appropriate (and less than 60% greater than for example 20%) to set the covering ratio alpha ₀ represented by a, compared with the conventional structure covering ratio of 60% which corresponds to the optimum value in the bell-mouth shape, at least The noise can be reduced to the same extent without reducing the cooling air flow. Therefore, the cooling efficiency can be improved.

(2) In the above (1), preferably,
An intake hole for introducing the air flow for cooling the heat exchanger and the engine into the cover is provided at an upper portion of the cover, and the air flow after cooling the heat exchanger and the engine is removed from the cover. Exhaust holes to exhaust
It is provided below the engine.

When the intake hole for the airflow is provided above the cover and the exhaust hole is provided below the engine from the viewpoint of reducing noise to the surroundings, the curved shape of the airflow passage becomes remarkable. The airflow is more likely to be disturbed because the flow path resistance increases. Therefore, in this case, the above-described turbulence reduction effect according to the present invention is particularly effective.

(3) In the above (1) or (2), preferably, the width of the blade in the rotation axis direction is L ₀ ,
When the distance from the heat exchanger-side end of the blade to counter the heat exchanger-side end portion of the fan outer peripheral portion of the shroud was L _10, index covering represented by α ₀ = L ₁₀ / L ₀ α ₀ ,
More than 20% and less than 60%.

(4) In order to achieve the above object, according to the present invention, there is provided a traveling body, a main frame rotatably mounted on an upper part of the traveling body, and a horizontal frame centered on a vertical pin on the main frame. A swing post mounted rotatably in the direction, an articulated front device including a boom mounted rotatably in the up and down direction on the swing post, and a cab provided on the main frame,
A fan that covers most of the main frame other than the operator's cab, houses a heat exchanger such as a radiator and an oil cooler, and an engine, and a fan that generates an air flow by rotating an impeller having a number of blades. A cooling device for cooling the heat exchanger and the engine housed in the cover with an airflow generated by the fan, the cooling device including a shroud provided on an upstream side of the fan for introducing the airflow to a suction side of the fan; And, the front device swings the boom to the maximum, and when the boom is in the front minimum turning posture closest to the upper surface of the cover, the boom is moved rearward to a position on the side of the cab. In a construction machine in which the inclination and thereby the turning radius in the front minimum turning posture are reduced, the fan is driven by the driving force of the engine. An axial flow fan having a substantially horizontal rotating shaft, wherein the shroud includes a fixing mounting portion fixed to the heat exchanger, and a blade of the fan on a side opposite to the heat exchanger of the fixing mounting portion. This is a cylindrical shroud provided with a substantially cylindrical fan outer peripheral portion surrounding the outer peripheral side of the vehicle.

When the boom is tilted backward to the position on the side of the cab when the front is in the minimum turning posture, the so-called small rear turning type construction machine in which the turning radius is reduced thereby restricts the space in the cover and the degree of sealing. Since the increase in the flow path resistance increases, the air flow is particularly likely to be disturbed. Therefore, also in this case, the above-described turbulence reduction effect according to the present invention is particularly effective.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hydraulic shovel will be described below with reference to the drawings. FIG. 1 shows the entire structure of a hydraulic shovel to which the present invention is applied, and FIG. 2 is a partially transparent perspective view of the hydraulic shovel shown in FIG. 1 as viewed obliquely from behind.

In FIGS. 1 and 2, the hydraulic excavator includes a traveling body 2 having left and right crawler tracks 1L and 1R.
And a main frame 3 which forms a foundation lower structure of a revolving unit which is rotatably mounted on the upper portion of the traveling unit 2, and which is rotatable horizontally about a vertical pin (not shown) on the main frame 3. A swing post 4 attached to the swing post 4, an articulated front device 5 attached to the swing post 4 so as to be vertically rotatable, and a counter weight 6 attached to a rear end of the main frame 3. An operator cab 7 provided on the main frame 3 and a cover 8 covering most of the main frame 3 other than the operator cab 7 are provided.

The traveling body 2 has a substantially H-shaped track frame 9 and drive wheels 10L and 10R rotatably supported near the rear ends of the left and right sides of the track frame 9.
And left and right running motors 11L and 11R for driving the driving wheels 10L and 10R, respectively, and rotatably supported near the left and right front ends of the track frame 9 via the endless track tracks 1L and 1R. Rotating wheels (idlers) 12L, 1 which are respectively rotated by the driving force of the driving wheels 10
2 </ b> R and a blade 14 for discharging soil, which is provided in the front of the track frame 9 so as to be vertically movable and which is vertically moved by a blade cylinder 13. The traveling body 2
A swivel bearing 15 is disposed at the center of the pivot table.

The multi-joint type front device 5 includes a boom 16 which is a two-piece boom including a lower boom 16L and an upper boom 16U, and the upper boom 1
6U, an arm 17 rotatably coupled to the arm 17, a bucket 18 rotatably coupled to the arm 17, and one end connected to the upper boom 16U.
And a cross rod 19 for changing the angle between U and the lower boom 16L. This cross rod 19
Functions as a link member that regulates the shape of the front device 5, and the main frame 3 of the lower boom 16L
The angle between the upper boom 16U and the lower boom 16L is changed in accordance with the rotation angle with respect to. Then, the lower boom 16L, the arm 1
7 and the bucket 18 are respectively connected to the boom cylinder 2
0, an arm cylinder 21, and a bucket cylinder 22.

The swing post 4 is connected to a swing cylinder 23 provided on the main frame 3 via a connecting pin (not shown). By moving, the articulated front device 5 swings left and right.

A turning motor 24 for turning the main frame 3 with respect to the traveling body 2 is disposed near the center of the main frame 3. At this time, although not particularly clearly shown, the main frame 3 is configured to be capable of turning within a diameter close to the vehicle width of the traveling body 2 (= a diameter slightly larger than the vehicle width). Further, when the boom 16 is swung up to the maximum and the boom 16 takes the minimum turning posture in which the boom 16 comes closest to the upper cover 8, the lower boom 16 </ b> L is raised and the multi-joint type front device 5 is folded (see FIG. 1). State), the articulated front device 5 is within the turning radius of the main frame 3,
In other words, the vehicle 2 is configured to be able to turn within a diameter close to the vehicle width.

The driving devices described above, that is, the blade cylinder 13 and the swing motor 2 described above,
4. The hydraulic actuators such as the boom cylinder 20, the arm cylinder 21, the bucket cylinder 22, the swing cylinder 23, and the left and right running motors 11 are not described in detail, but a known hydraulic drive device (for example, 189298 or JP-A-7-26592). That is, these driving devices include operating means (left and right traveling levers 25L, 25R, swing pedal 26, left and right working levers 27L, 27R, described later) operated by an operator in the cab 7.
In response to the operation of a blade lever or the like, it is driven by pressure oil from a control valve device (not shown) that controls pressure oil from a hydraulic pump 33 (same as above) driven by an engine 32 (described later).

On the other hand, the cab 7 is provided on the left side of the main frame 3. Inside the cab 7, left and right running levers 25L, 25 for driving left and right running motors 11L, 11R of the running body 2, respectively.
R, a swing pedal 26 for driving the swing cylinder 23 to swing the articulated front device 5, the boom cylinder 20, the arm cylinder 2
1 and left and right working levers 27L and 27R for driving the lower boom 16L, the arm 17 and the bucket 18 by driving the bucket cylinder 22, respectively, and for driving the blade cylinder 13 to move the blade 14 up and down. And a blade lever (not shown). The cab 7 includes a seat 28 (see FIG. 3 described later) and a roof 29 provided above the seat 28.
And a rear wall 30 provided behind the seat 28, and a side wall 31 provided on the inner side (right side) of the seat 28. Most of the rear wall 30 and the side wall 31 are mostly provided. It is formed of a transparent material and is disposed substantially vertically.

As shown in FIG. 2, the upper cover 8 has an engine 32 therein.
Hydraulic pump 3 connected to and driven by its driving force
3. Fuel tank 3 for storing fuel of the engine 32
4. Hydraulic oil tank 3 serving as a pressure oil source for the hydraulic pump 33
5. An air cleaner 36 for purifying the intake air to the engine 32, an intake pipe 37 connected to the air cleaner 36 (see FIG. 3 described later), and exhaust gas from the engine 32 is guided to muffle the exhaust gas. An muffler 38 and an engine chamber 40 for accommodating equipment such as an exhaust gas pipe 39 having one end connected to the discharge side of the muffler 38 and the other end exposed through the through hole 6a of the counterweight 6 to the outside. I have. In the lower rear part of the upper cover 8,
Opening / closing door 4 for maintenance inside the engine room 40
The counter weight 6 is located below the door 41. The hydraulic oil tank 35 is provided with the hydraulic pump 33 and the oil cooler 46.
(See FIG. 3 to be described later) and the like by piping not shown.

An embodiment of the cooling device of the present invention is provided in such an engine room 40. FIG. 3 is a horizontal sectional view of the revolving superstructure 2 showing a detailed structure inside the engine room 40 provided with an embodiment of the cooling device of the present invention.
FIG. 4 is a vertical sectional view of the engine compartment 40 shown in FIG.
FIG. 5 is a detailed enlarged view of a portion B in FIG. 4, and FIG.
It is sectional drawing by the middle VI-VI cross section. 3 to 6, those having the same reference numerals as those in FIGS. 1 and 2 indicate the same parts. 3 to 6, the engine 32 is installed on the main frame 3 via a vibration damping device (also referred to as an engine mount, not shown). The cooling device according to the embodiment of the present invention
A cooling fan 44 provided on one side of an auxiliary rotating shaft (fan rotating shaft) 43 connected to the crankshaft 32a via a crank pulley 32b, a fan belt 42, and a fan pulley 43a; A radiator 45 and an oil cooler 46 as heat exchangers arranged on the (upstream side), and a partition member 47 for fixing the radiator 45
A shroud 48 fixed downstream of the radiator 45; and a radiator 45 of the upper cover 8.
And air intake holes 49a (installed at the upper portion of the cover) and 49b (installed at the lower portion of the cover) provided in the upstream portion of the oil cooler 46, and the main body for discharging the airflow flowing out of the cooling fan 44 to the outside. An exhaust hole 50 is provided in the frame 3 directly below the engine 32.

As the cooling fan 44, an axial fan is used similarly to a cooling device of this type of ordinary construction machine, and as shown in FIG. They are arranged horizontally. A water pump (not shown) for circulating engine cooling water to the radiator 45 is connected to the other side of the auxiliary rotation shaft 43. The opposite side of the crankshaft 32a (the left side in FIG. 4)
Is connected to a hydraulic pump 33 via a gear mechanism (not shown) (or may be directly connected).

The radiator 45 includes a hose 51a,
The cooling water of the engine 32 is circulated and supplied through 51b to cool it, and the oil cooler 46 communicates with the various actuators via a pipe (not shown) on the upstream side, and a pipe (not shown) on the downstream side. Through the hydraulic oil tank 35. Thereby, the hydraulic pump 3
The cooling oil supplied from 3 to the actuator is cooled.

The shroud 48 is a so-called cylindrical shroud, and as shown in FIG.
Mounting portion 48a which is fixed to the vehicle via a bolt 54
And the fan 4 on the side opposite to the radiator of the mounting portion 48a.
And a substantially cylindrical fan outer peripheral portion 48b surrounding the outer peripheral side of the fourth impeller. A fan guard (not shown) is fixed to the fan outer peripheral portion 48b via bolts to prevent danger to workers. At this time, the shroud 48 has a width L _{0 in} the axial direction of the auxiliary rotating shaft 43 of the plurality of blades 44 a (for example, retreating blades) attached to the hub 44 b of the cooling fan 44, and the radiator 45 side of the blades 44 a. when the distance from the end portion 44aa to counter the radiator end 48ba of the shroud fan outer peripheral portion 48b was set to L _10, the covering ratio α ₀ = L ₁₀ / L ₀ is set to 22%. Also, a predetermined chip clearance t is provided between the inner peripheral side of the shroud fan outer peripheral portion 48b and the blade 44a.

The space in the upper cover 8 is divided by the partition 53 into the engine room 40 as a rear region where the radiator 45, the oil cooler 46, the engine 32, the cooling fan 44 and the like are arranged, and the other front region. And a fuel tank chamber 52. At this time, the partition wall 53 also serves as a part of the rear wall 30 of the cab 7 described above.

The space inside the upper cover 8, particularly the engine room 40, is set smaller in airtightness than in the prior art in a manner corresponding to the tendency to reduce noise in recent years, which will be described later, and the intake holes 49a, 49b are provided. Also, the opening area of the exhaust hole 50 is set to be relatively small. In addition, at this time, the intake hole normally provided at one place on the side of the cover 8 is divided into two upper and lower intake holes 49a and 49b (see FIG. 4). By doing so, the same sound insulation ability can be provided even if the opening area is wider than in a normal case where one intake hole is provided on the side.

The operation of the above-described embodiment of the cooling device of the present invention will be described. When the engine 32 is driven, the rotation of the crankshaft 32 a of the engine 32 is transmitted to the auxiliary rotation shaft 43 via the belt 42, and the rotation of the auxiliary rotation shaft 43 causes the cooling fan 44 to rotate. By the rotation of the cooling fan 44, the airflow P is sucked from the intake holes 49a and 49b, and cools the oil cooler 46 and the radiator 45. Then, the airflow P that has passed through the oil cooler 46 and the radiator 45 flows into the cooling fan 44 via the shroud 48. Air flow P flowing into cooling fan 44
Is boosted by the cooling fan 44 and flows out.
To the outside (below the revolving superstructure 2) through the exhaust hole 50.
Will be released.

Next, the operation of the embodiment of the cooling device of the present invention configured as described above will be described.

(1) Reduction of Turbulence and Improvement of Productivity Due to Cylindrical Shroud In the above-described flow path of the airflow P, the cooling fan 44 is an axial fan having the substantially horizontal rotating shaft 43. Due to its characteristics, the oil cooler 46 and the radiator 45 located at the upstream position and the engine 32 located at the downstream position become flow path resistance, and are affected by the flow resistance.
The front and rear air flow is easily disturbed. Therefore, in the present embodiment, by providing a cylindrical shroud 48 on the outer peripheral side of the impeller of the cooling fan 44, the airflow P passing through the oil cooler 46 and the radiator 45 is smoothly introduced into the cooling fan 44 to be disturbed. Can be reduced. At this time, since the fan outer peripheral portion 48a is formed in a substantially cylindrical shape, the curved portion and the flat portion are not complicatedly mixed as in the conventional structure having a bell mouth shape, so that processing is extremely simple. And productivity can be improved.

(2) Improvement of Cooling Air Volume and Noise Reduction by Setting Coverage Ratio In the present embodiment, in addition to the above-described operation (1), the coverage ratio α ₀ is set in an optimum range, so that the conventional structure is optimized. Compared to the case where the covering ratio is 60% corresponding to the value, the noise can be reduced to the same extent without reducing the cooling air volume at least. Hereinafter, this operation will be described in detail.

(2-A) Background of Increasing the Sealing As described above, the cover needs an opening for cooling the engine and the auxiliary equipment, etc., and is generated from the engine and the auxiliary equipment through the opening. This must be taken into account because noise will be radiated to the surrounding environment. If the opening is widened and the degree of sealing in the cover is reduced, ventilation efficiency is reduced due to reduced ventilation resistance, but noise to surroundings is increased. Conversely, increasing the degree of sealing reduces noise to the surroundings, but decreases cooling efficiency.

In the conventional construction machines, the standard of noise regulation was looser than the current one, and therefore, the emphasis was mainly on improving the cooling efficiency. For this reason, the opening is relatively large, the degree of sealing is relatively low, and the ventilation resistance of the cooling fan is relatively low.

However, in recent years, there has been a strong demand for reduction of noise from construction machinery to the surroundings based on changes in the working environment and demands for preservation of the surrounding environment, and construction with a noise standard that conforms to national and European noise regulations. There is an urgent need to develop machines.

As an example of the criterion, the conventional noise evaluation is the evaluation at the maximum engine no-load rotation speed when the body of the construction machine is in a static state (ie, the stationary noise evaluation). Instead, when the vehicle body of the construction machine is in a dynamic state, specifically, an evaluation under a simulated workload including excavation, running, turning operation, and the like (ie, work noise evaluation) is required. In addition, the conventional noise measurement has been performed in a plane at a plurality of locations at a predetermined distance from the vehicle body in four directions on the side of the vehicle body. Instead, the noise measurement is three-dimensionally performed at a plurality of locations on a hemisphere surrounding the vehicle body. Done. Furthermore, the conventional noise measurement was sufficient if the vehicle body was arranged on a solid ground surface, but instead of this, for example, a hydraulic shovel is basically arranged and measured on concrete or asphalt,
In the case of solid soil, there is an obligation to add a correction value to the measured noise value.

Against this background, future construction machines are required to have a lower noise level than the current level. To further reduce the noise level, the number of openings in the cover is reduced. It tends to increase the degree of sealing of the cover. As a result, the opening areas of the inlet opening and the outlet opening of the cooling air are reduced, the resistance when the cooling air flows in and out is increased, and the total ventilation resistance applied to the cooling fan tends to increase.

(2-B) Relationship Between Sealing Degree and Covering Ratio By the way, the covering ratio α ₀ which determines the relative positional relationship between the cooling fan and the shroud in the axial direction depends on the pressure condition at which the cooling fan operates. The optimal arrangement is determined. This will be described with reference to FIG.

FIG. 7 is a diagram for explaining the flow near the shroud, and is a cross-sectional view taken along the line VII-VII in FIG. As shown in the drawing, the cooling air (air flow P) flowing out of the fan 44 is applied to the circumferential velocity vector V of the blade 44a.
with the _r, the absolute velocity vector V is the resultant vector of the relative velocity vector V _w for the cooling air of the blade 44a. The absolute velocity vector V, when considered decomposed into the axial component V ₁ is a component corresponding to the air volume and circumferential component V _2, the ventilation resistance of the vehicle body is increased, at the same fan speed the absolute velocity vector V of the cooling air will have more the circumferential component V _2.

Since the circumferential component V ₂ is a component in the direction of colliding with the shroud 48, if the cooling air has more circumferential component V ₂ , the flow path resistance near the shroud 48 increases. Become. Therefore, in order to secure the same cooling air volume, in order to reduce the flow path resistance near the shroud 48, it is necessary to reduce the covering ratio α ₀ and reduce the fogging amount between the cooling fan 44 and the shroud 48. is there.

Here, as described in (2-A) above, in future construction machines, the ventilation resistance on the vehicle body side will increase due to the increase in the degree of sealing of the cover, so that the flow path resistance near the shroud 48 will increase. . Therefore, in order to ensure the same amount of cooling air, it is necessary to reduce the covering ratio alpha _0.

In a conventional construction machine, the covering ratio of the cooling fan is given by the background of the relatively small sealing degree based on the relatively loose noise regulation standard as described in the above (2-A).
For example, as described in JP-A-8-284611, about 60% was the optimum value. However, under the background of the increase in the degree of sealing as described above, this value is not always an appropriate value (it is necessary to reduce the covering ratio in order to reduce the flow path resistance near the shroud).
It is necessary to reconsider the optimal covering ratio value.

(2-C) Appropriate Range of Covering Ratio The inventors of the present invention conducted an experiment for examining an appropriate covering ratio based on the above considerations, and obtained the results shown in FIG.

FIG. 8 shows a structure similar to that of the present embodiment shown in FIGS. 3 to 6, in which the rotation speed of the engine 32 is set to a rotation speed close to the rated rotation speed with a large load, and the cooling fan The wind speed and the noise at the front (upstream side) of the radiator 45 when the covering ratio α ₀ of the shroud 44 and the shroud 48 are variously changed are measured. Note that the vertical axis of the wind speed is represented by a relative value [%] with respect to the value when the covering ratio α ₀ = 50%, and the vertical axis of the noise is the deviation [dB () from the value when the covering ratio α ₀ = 50%. A)].

In FIG. 8, the wind speed was measured by setting the covering ratio to α ₀ = 22%, 38%, 50%, and 63%. As shown in the figure, the measured value has a downward-sloping curve with respect to the increase in the covering ratio α ₀ ,
Wind speed value increases as the covering ratio α ₀ becomes smaller is increasing.
This indicates that as the covering ratio α ₀ becomes smaller, the flow path resistance near the shroud 48 due to the collision of the flow of the cooling air discharge unit becomes smaller, and the air volume increases. Although not shown, this tendency did not change even when the engine speed was changed.

For the noise, the covering rate is α ₀ =
The measurement was performed by setting 22%, 50%, and 63%, respectively. Measurements, as shown, has a slight increase with increasing covering ratio alpha _0, almost no change. It was found that at least in any of the cases where the covering ratio α ₀ = 22% and 63, the noise value was almost the same as the covering ratio α ₀ = 50%. As for the noise, this tendency did not change even when the engine speed was changed, similarly to the above wind speed.

By the way, the covering ratio α _{0 under the} measuring conditions
Is set to 22% for the following reason. That is, when the covering ratio α ₀ is actually reduced, there is not much room in the space inside the engine room 40, and the cooling is performed by shortening the auxiliary rotating shaft 43 while keeping the arrangement of the engine 32, the radiator 45 and the shroud 44. Fan 44
Is shifted to the engine 32 side (the left side in FIG. 4).

In this type of engine room 40, although not specifically shown in FIGS. 3 and 4, a compressor for an air conditioner is usually installed, and the crankshaft 32a in FIG. In many cases, a pulley that extends further to the right side than the pulley 32b and provides a driving force to the compressor is provided. Therefore, the covering rate α ₀
Is too small, the cooling fan 44 will interfere with the pulley for the compressor. According to the studies made by the inventors of the present application, it has been found that in order to avoid this interference, the covering ratio α ₀ must be at least larger than 20%.

From the above, the present inventors have found the following. In a structure in which the degree of sealing is improved in recent years to reduce noise, the covering ratio α ₀ = 60% of the conventional structure is not always an optimum value, and the covering ratio α ₀ is at least 60%.
Shift to the smaller side. When α ₀ <60%, the wind speed (in other words, the air volume) can be increased more than at least when α ₀ = 60%. When α ₀ <60%, a noise reduction effect equivalent to at least α ₀ = 60% can be obtained. From the viewpoint of preventing interference with the compressor pulley, α
₀ > 20%.

As described above, the inventors of the present application have determined that the covering ratio α
_It was determined that 20% <α ₀ <60% was appropriate as an appropriate range of ₀ .

As described above, in the present embodiment, the covering ratio α ₀ = L ₁₀ / L _{0 is set} to 22%, which is within this range. As a result, while preventing interference with the compressor pulley, the optimum value (coverage ratio of 6
0%), the noise can be reduced to the same extent at least without reducing the amount of cooling air. Therefore, the cooling efficiency can be improved.

(3) Others As described above, in the engine room 40 of this embodiment, the intake holes 49a, 49a,
49b are arranged vertically, and as a result, as shown in FIG. 4, the intake holes 49a, 49b → the cooling fan 4
4 → The cooling air flow path of the exhaust hole 50 is bent. Therefore, this also increases the flow path resistance, and the air flow before and after the fan is easily disturbed. Therefore, the turbulence reduction effect described above in (1) is particularly effective in such an engine room 40 of this type.

As described above, the hydraulic excavator to which the present embodiment is applied is a so-called micro-swirl type construction proposed in response to the needs for work at a recent small excavation site. It is a machine. In such a model, the space in the upper cover 8 is narrower than that of a normal construction machine, and the degree of freedom in arranging the devices is also limited. This also increases the flow path resistance and makes the air flow around the fan easily turbulent. ing. Therefore, the turbulence reduction effect described above in (1) is particularly effective in such a construction machine.

As described above, according to the embodiment of the present invention, since the cylindrical shroud 48 provided with the fan outer peripheral portion 48b is used, the shroud has a smaller shape than the conventional structure having a bell mouth shape. Processing becomes extremely simple, and productivity can be improved. In addition, since the covering ratio α ₀ is set to 22%, which is more than 20% and less than 60%, the noise is at least as low as the optimal value α ₀ = 60% in the conventional structure without lowering the cooling air volume. Reduction can be achieved. Therefore, the cooling efficiency can be improved.

In the above-described embodiment of the present invention, the blade 44a of the cooling fan 44 is constituted by the retreating wing. However, it is apparent that the same effect can be obtained when the cooling fan 44 is constituted by the forward wing. It is.

Further, in the above-described embodiment of the present invention, the case where the present invention is applied to a so-called suction type cooling device as described above has been described as an example. However, the present invention is not limited to this. May be applied.

[0072]

According to the present invention, as the shroud, a fixing mounting portion fixed to the heat exchanger, and a substantially cylindrical shape surrounding the outer peripheral side of the fan impeller on the side opposite to the heat exchanger of the mounting portion. Since a cylindrical shroud having a fan outer peripheral portion is provided, the cooling air can be smoothly introduced in a shape that can be easily processed, and noise can be reduced while securing a cooling air volume, thereby improving productivity. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire structure of a hydraulic shovel to which the present invention is applied.

FIG. 2 is a partially transparent perspective view of the hydraulic excavator shown in FIG. 1 as viewed obliquely from behind.

FIG. 3 is a horizontal sectional view of a revolving superstructure showing a detailed structure inside an engine room provided with a cooling device according to an embodiment of the present invention.

FIG. 4 is a vertical sectional view of the engine compartment shown in FIG.

FIG. 5 is an enlarged view of a portion A in FIG. 4;

FIG. 6 is a sectional view taken along a line VI-VI in FIG. 5;

FIG. 7 is a diagram for explaining a flow near a shroud according to an embodiment of the cooling device of the present invention, and is a diagram VII in FIG. 5;
FIG. 7 is a cross-sectional view taken along the line VII.

FIG. 8 is a diagram showing the results of measuring the wind speed and noise at the front of the radiator when the covering ratio α ₀ of the cooling fan and the shroud is variously changed in the same structure as that of the cooling device according to the embodiment of the present invention. is there.

FIG. 9 is a cross-sectional view of an example of a conventional hydraulic excavator as viewed from the rear thereof.

FIG. 10 is a partially enlarged view of FIG. 9;

11 is a view as seen in the direction of the arrow XI-XI in FIG. 10;

FIG. 12 is a cross-sectional view of another example of the conventional hydraulic shovel viewed from the rear.

FIG. 13 is an enlarged view of a portion A in FIG.

FIG. 14 is a diagram showing a result of a noise measurement experiment in a conventional structure.

[Explanation of symbols]

 2 Traveling body 3 Main frame 4 Swing post 5 Front device 7 Operator cab 8 Cover 32 Engine 44 Cooling fan (Fan) 45 Radiator (Heat exchanger) 46 Oil cooler (Heat exchanger) 48 Shroud 48a Fixing attachment 48B Part 49a, b Intake hole 50 Exhaust hole

Claims (4)

[Claims] 1. A fan which generates an air flow by rotation of an impeller having a number of blades, and a shroud provided upstream of the fan and for introducing the air flow to a suction side of the fan, Heat exchangers and engines such as radiators and oil coolers arranged in a cover that covers the revolving superstructure,
In a cooling device for a construction machine that cools with an airflow generated by the fan, the fan is an axial fan having a substantially horizontal rotating shaft driven by a driving force of the engine, and the shroud is The shroud is a cylindrical shroud having a fixing mounting portion fixed to the heat exchanger and a substantially cylindrical fan outer peripheral portion surrounding the outer peripheral side of the fan impeller on the side opposite to the heat exchanger of the mounting portion. A cooling device for construction machinery. 2. A cooling device for a construction machine according to claim 1, wherein an air inlet for introducing an air flow for cooling said heat exchanger and said engine into said cover is provided at an upper portion of said cover. A cooling device for a construction machine, wherein an exhaust hole for discharging a heat exchanger and an airflow after cooling the engine to outside of the cover is provided below the engine. 3. The cooling device for a construction machine according to claim 1, wherein the width of the blade in the rotation axis direction is L ₀ , and the fan outer peripheral portion of the shroud from the heat exchanger side end of the blade. anti heat when the distance to the exchanger-side end portion was set to L _10, the covering ratio alpha ₀ represented by _{α 0 = L 10 / L 0} , characterized by being 60% less than than 20% of the Cooling equipment for construction machinery. 4. A traveling body, a main frame pivotally mounted on an upper portion of the traveling body, a swing post mounted on the main frame so as to be pivotable in a horizontal direction about a vertical pin, and A multi-joint type front device including a boom that is attached to the swing post so as to be rotatable in the vertical direction, a cab provided on the main frame, and covers most of the main frame other than the cab, A cover for housing a heat exchanger such as a radiator and an oil cooler, and an engine; a fan for generating an air flow by rotation of an impeller having a number of blades; and a fan provided upstream of the fan to generate the air flow. A cooling device for cooling the heat exchanger and the engine housed in the cover with an airflow generated by the fan, comprising a shroud introduced to a suction side; And the front device swings the boom to the maximum, and when the boom is in a front minimum turning posture in which the boom is closest to the upper surface of the cover, the boom is moved rearward to a position on the side of the cab. In the construction machine in which the turning radius in the front minimum turning posture is reduced, the fan is an axial fan having a substantially horizontal rotating shaft driven by the driving force of the engine, The shroud includes a fixing mounting portion fixed to the heat exchanger, and a substantially cylindrical fan outer peripheral portion surrounding an outer peripheral side of the fan impeller on a side opposite to the heat exchanger of the fixing mounting portion. A construction machine characterized by being a cylindrical shroud.