WO2013081010A1

WO2013081010A1 - Construction machine

Info

Publication number: WO2013081010A1
Application number: PCT/JP2012/080754
Authority: WO
Inventors: 茂久舩橋; 岩瀬　拓; 慎松下; 昌紀江沢; 知憲儘田; 渡邉　修
Original assignee: 日立建機株式会社
Priority date: 2011-11-29
Filing date: 2012-11-28
Publication date: 2013-06-06
Also published as: DE112012004976B4; DE112012004976T5; JP5883278B2; US20140301839A1; JP2013113225A

Abstract

Provided is a highly efficient and quiet construction machine, wherein a heat exchanger has a satisfactory wind speed distribution and impact by air flowing out from an axial flow fan on an engine can be avoided. In a construction machine provided with an axial flow fan (2) having a plurality of rotor blades (2a), a fan ring (3) for leading air flow to the axial flow fan, a heat exchanger (1) disposed upstream or downstream in the air flow from the axial flow fan, and a structural body (4) disposed downstream in the air flow from the axial flow fan, the fan ring has an intake-side R-shaped part (3a) for constricting an intake-side flow channel and a discharge-side R-shaped part (3b) for expanding a discharge-side flow channel, the rotor blades are inclined at an angle of advance θ in the rotational direction from the axial center and are attached so as to be inclined forward toward the intake side, and when the axial flow fan is attached to the inner side of the fan ring, first intersection points (P) where the rear edges and outer peripheral edges of the rotor blades meet are positioned within a range the width of the discharge-side R-shaped part.

Description

Construction machinery

The present invention relates to a construction machine including a cooling device that supplies cooling air to a heat exchanger such as a radiator by an axial fan.

Generally, in a construction machine such as a hydraulic excavator, a hydraulic pump is driven by a diesel engine, and excavation work or traveling is performed using the hydraulic energy. Therefore, in the engine room, together with the engine and the hydraulic pump, a radiator for cooling the engine, a heat exchanger such as an oil cooler for cooling the hydraulic oil, and cooling air for supplying these heat exchangers A cooling fan is arranged.

For example, Patent Document 1 is known as background art in this technical field. This Patent Document 1 discloses an example of cooling a heat exchanger for a construction machine using a low-cost and thin axial flow fan. In this example, the axial flow fan is connected to an engine crankshaft. It is configured to rotate by power transmitted through a pulley and a fan belt. In many cases, the heat exchanger is located upstream of the axial flow fan, and the air flowing in from the outside through the intake port passes through the heat exchanger and is then guided to the axial flow fan by a fan shroud and fan ring. Is done. The air pressurized by the axial fan flows around the engine (structure) and is discharged to the outside through the exhaust port.

In recent years, in order to comply with exhaust gas regulations for diesel engines mounted on construction machinery, construction machinery also uses air-cooled intercoolers and water-cooled EGR (Exhaust Gas Recirculation) equipment as a means to reduce exhaust gases. Installation is carried out. In addition, suppression of exhaust gas has been promoted by installing a common rail and controlling fuel injection timing.

JP 2010-270670 A

Due to the above-mentioned exhaust gas countermeasures, in addition to the radiator and oil cooler that have been installed in the past, a new heat exchanger called an intercooler has been added, and it is also necessary to improve the radiator's heat dissipation performance in order to cool the water-cooled EGR device. For example, the amount of air necessary for cooling has increased in recent construction machines.

In addition, heat exchangers have been increased in size as the cooling load increases. However, the number of devices mounted in the limited space in the engine compartment has increased, so there is a limit to that. . In the case of a machine in which the front area of the heat exchanger cannot be increased any more, the size of the heat exchanger is increased in the direction of increasing the thickness of the heat exchanger.

However, when the front area of the heat exchanger is enlarged, the end of the heat exchanger is separated from the fan because the heat exchanger is relatively large with respect to the fan, and cooling air flows through that portion. It becomes difficult. For this reason, it becomes difficult to fully exhibit the effect which enlarged the heat exchanger. If the dimensions allow, it is possible to increase the diameter of the fan in accordance with the heat exchanger. However, increasing the driving power of the fan limits the power that can be used as a construction machine.

On the other hand, when the size of the heat exchanger is increased to increase the thickness, the space in the direction of the rotation axis of the fan is narrowed accordingly. Accordingly, when the distance between the heat exchanger and the fan is reduced, the wind speed distribution of the air passing through the heat exchanger is deteriorated. If the distance between the fan and the engine is reduced, the flow out of the fan is likely to collide with the engine, thereby increasing the pressure loss in the cooling air flow path. Therefore, the number of fan rotations required to obtain the necessary air volume increases, and as a result, the fan shaft power and noise increase, leading to an increase in construction machine noise and fuel consumption.

In addition, in the case of construction machines, it is not possible to expect the intake of cooling air by running wind as in the case of automobiles, so all necessary cooling air volume must be sucked in by a fan. Therefore, the rotational speed of the fan is set higher than that of the automobile, and the fan shaft power and noise are likely to be high. This will affect the fuel consumption and noise of the entire construction machine.

The present invention has been made in view of the above-described circumstances, and its purpose is to achieve a high efficiency and low efficiency in which the air velocity distribution of the heat exchanger is good and the collision of the air flowing out of the axial fan with the engine can be avoided. It is to provide noise construction machinery.

In order to solve the above-mentioned problems, the present invention has an axial fan having a plurality of blade pieces and rotating around an axis, and is disposed around the axial fan. A fan ring for guiding, a heat exchanger disposed upstream or downstream of the air flow from the axial fan, and a structure disposed downstream of the air fan from the axial fan. In the construction machine, the fan ring has a suction side R-shaped portion that reduces the flow path on the suction side and a discharge-side R-shaped portion that expands the flow path on the discharge side, and the blade piece has a leading edge And a rear edge and an outer peripheral edge. The axial fan is attached in a posture inclined at a forward angle θ from the axial center toward the rotational direction and forwardly inclined toward the suction side. In the state of being attached to the inside of the ring, the trailing edge of the wing piece and the outer First intersection point where the edge intersection is characterized by being located within the width of the discharge-side R-shaped portion.

According to the present invention configured as described above, the suction side of the axial flow fan can be a centripetal flow and the discharge side can be a centrifugal flow, so that the air flow is more upstream than the axial flow fan. With respect to a large heat exchanger arranged on the side or the downstream side, it becomes possible to flow cooling air with a good wind speed distribution to the end portion. In addition, it is possible to prevent the air flowing out from the axial fan from colliding with a structure such as an engine on the downstream side, thereby preventing an increase in pressure loss in the cooling air flow path.

And according to this invention, since the thermal radiation performance in a heat exchanger can be improved and the hot air around an engine can be ventilated efficiently, generation | occurrence | production of the engine or hydraulic oil overheating can be suppressed. Furthermore, if the heat dissipation performance of the heat exchanger is improved and the pressure loss in the cooling air flow path is reduced, the air volume necessary for cooling can be reduced, and the rotational speed of the axial fan can be suppressed. This contributes to noise suppression and improved fuel efficiency by reducing driving power.

In the above configuration, the advance angle θ is preferably in the range of 5 ° to 25 °. With this configuration, even if the rotational speed of the axial fan is increased in order to obtain the designed air volume (100% Q), a level that is not felt by humans (ie, +3 dB or less) ). Moreover, even if the pressure loss increases due to the resistance of the structure located on the cooling air discharge side, it does not fall below the allowable lower limit (ie, −10%) of the air flow reduction.

Further, in the above configuration, it is preferable that the second intersection point where the front edge and the outer peripheral edge of the blade piece intersect is at a position protruding from the suction side R-shaped portion to the upstream side of the air flow. If comprised in this way, since the centripetal flow on the suction side and the centrifugal flow on the discharge side of the axial flow fan become smoother, the heat dissipation performance of the heat exchanger is further improved.

According to the present invention, it is possible to provide a high-efficiency, low-noise construction machine that maintains a favorable wind speed distribution of the heat exchanger and avoids collision of air flowing out of the axial fan with the engine.

1 is an external perspective view of a hydraulic excavator according to a first embodiment of the present invention. It is a sectional side view of the engine room of the hydraulic excavator shown in FIG. It is the side view to which the principal part of the axial fan shown in FIG. 2 and a fan ring was expanded. It is the top view to which the principal part of the axial fan shown in FIG. 2 was expanded. It is a figure which shows the relationship between the advancing angle of the blade | wing of the axial flow fan shown in FIG. 2, and relative noise. It is a figure which shows the relationship between the advancing angle of the blade | wing of the axial fan shown in FIG. 2, and the air volume change at the time of pressure loss increase. It is a sectional side view of the engine room of the hydraulic shovel which concerns on 2nd Example of this invention.

Hereinafter, a hydraulic excavator which is an embodiment of a construction machine according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the hydraulic excavator according to the first embodiment is attached to a crawler 24, an upper swing body 26 disposed on the crawler 24, and the upper swing body 26 so as to be rotatable in the vertical direction. The front working machine capable of performing excavation work and the like, and the cab 25 as an operation room are provided. The front work machine includes a boom 21 that is attached to the upper swing body 26 so as to be able to move up and down, an arm 22 that is rotatably attached to the tip of the boom 21, and a bucket 23 that is rotatably attached to the tip of the arm 22. And a hydraulic cylinder for driving them. Further, the upper swing body 26 has the engine room 10 built in behind it. Reference numeral 27 denotes a counter weight 27.

As shown in FIG. 2, the engine room 10 includes an axial fan 2, a fan ring 3 that guides the air flow to the axial fan 2, a heat exchanger 1, an engine (structure) 4, A battery 9 is installed. In addition, an intake port 7 serving as an air inlet / outlet is provided in the upper portion of the engine chamber 10, and an exhaust port 8 is provided in the upper and lower portions of the engine chamber 10. The positional relationship among the heat exchanger 1, the axial fan 2 and the engine 4 is such that the heat exchanger 1 is upstream of the air flow from the axial fan 2 and the engine 4 is downstream of the air flow of the axial fan 2. is there. With such a positional relationship, the axial fan 2 is required to have a centripetal flow toward the center of the fan on the upstream side, and a centrifugal flow toward the centrifugal direction of the fan on the downstream side. Therefore, in this embodiment, forward / forward tilting blades are employed (details will be described later).

The heat exchanger 1 includes a radiator, an oil cooler, and an intercooler, and each device is arranged in parallel. In recent years, the size of the heat exchanger 1 has been increasing in order to increase the amount of heat exchanged, and in this embodiment as well, the overall outer shape of the heat exchanger 1 is relatively larger than the axial fan 2. Yes.

The engine 4 includes a crankshaft (output shaft) 4a, from which power for rotating the axial fan 2 is transmitted via the pulley 5 and the fan belt 6. Then, the fan 5 is adjusted to an appropriate fan rotation speed by the pulley 5, and the fan 2 rotates.

Next, the details of the axial fan 2 and the fan ring 3 will be described. As shown in FIG. 2, the axial fan 2 includes a cylindrical hub 2b attached to the rotary shaft 2c, and a plurality of blades (blade pieces) 2a provided around the hub 2b. . The fan ring 3 is formed in an annular shape, and is provided around the axial flow fan 2 as shown in FIGS. 2 and 3, and has a suction side R-shaped portion 3a having a curved surface on the suction side. It has a discharge side R-shaped portion 3b having a curved surface on the discharge side. That is, in the fan ring 3, the side edge on the suction side and the side edge on the discharge side are both formed in an R shape.

As shown in FIG. 3, the blade 2 a is formed to have a front edge 2 g, an outer peripheral edge 2 e, and a rear edge 2 d, and the axial fan 2 is attached inside the fan ring 3. The second intersection point Q where the front edge 2g and the outer peripheral edge 2e intersect is projected by a length L from the suction side R-shaped part 3a of the fan ring 3 to the upstream side (suction side), and the rear edge 2d and the outer peripheral edge 2e The first intersection point P where the two intersect with each other is positioned within the range of the width W of the discharge-side R-shaped portion 3 b of the fan ring 3.

Further, the detailed shape of the blade 2a will be described. As shown in FIG. 3, the blade 2a protrudes toward the suction side as the position has a larger diameter, and is inclined (forwardly inclined) as a whole. Further, as shown in FIG. 4, the blade 2 a protrudes in the rotational direction (moves forward) at a location having a larger radial position, and its advance angle is θ. That is, the blade 2a of the axial fan 2 used in this embodiment is a forward / forward tilting blade. Note that the advancing angle θ here indicates how much the trailing edge 2d of the blade 2a protrudes in the rotation direction, and specifically, the center point A of the rotating shaft 2c and the blade 2a. This is an inner angle A of the triangle AOP formed by connecting the third intersection point O where the rear edge 2d and the hub 2b intersect with the first intersection point P.

Next, the air flow by the axial fan 2 will be described. The arrows in FIGS. 2 and 3 indicate the flow of air. Generally, an axial fan with forward and forward inclined blades creates a centripetal flow that goes toward the rotation center of the fan on the upstream side (suction side), and partly sucks air from the side of the fan. have. Therefore, when the axial flow fan 2 rotates, a pressure difference is generated between before and after that, and an air flow is induced. First, low-temperature air outside the engine compartment 10 flows into the engine compartment 10 through the intake port 7. When the air passes through the heat exchanger 1, it takes heat of the fluid (engine cooling water, hydraulic oil, compressed air, etc.) in the pipe of the heat exchanger 1 and becomes high temperature. Thereafter, the refrigerant flows into the axial fan 2, is pressurized, flows out from the axial fan 2, flows around the engine 4, and is discharged from the exhaust port 8 to the outside of the engine room 10. By generating such a flow, even in the heat exchanger 1 that is relatively larger than the axial fan 2, an air flow can be made to the end portion, and efficient heat exchange can be realized.

On the other hand, the axial fan having forward and forward inclined blades is characterized in that air tends to flow out in the axial direction along the rotary shaft 2c on the downstream side (discharge side). Therefore, if it is as it is, the air which flowed out from the axial fan 2 may collide with the engine 4, and pressure loss may increase.

Therefore, in the case of the present embodiment, as shown in FIG. 3, the first intersection point P where the trailing edge 2d and the outer peripheral edge 2e intersect is positioned within the range of the width W of the discharge side R-shaped portion 3b of the fan ring 3. I try to let them. By doing in this way, since the air which flowed out from the axial fan 2 flows along the discharge side R-shaped part 3b of the fan ring 3 by the Coanda effect, the air flow is easily directed in the radial direction, and the centrifugal flow It becomes. As a result, the air flowing out from the axial fan 2 can be prevented from colliding with the engine 4 and the increase in pressure loss can be suppressed. Further, since the discharge side R-shaped portion 3b of the fan ring 3 also acts as a diffuser, it effectively decelerates the flow having a high absolute flow velocity flowing out from the first intersection P at the rear end of the blade 2a, and increases the static pressure. We can expect effect to make.

As can be seen from the above description, in the excavator of the present embodiment, the heat exchanger 1 can achieve effective heat exchange with a good wind speed distribution, and the downstream side of the axial flow fan 2 is outflowed. By avoiding a collision with the engine 4 due to the air, a flow path configuration with a low pressure loss can be realized.

On the other hand, in the hydraulic excavator, leakage of the noise of the axial fan 2 and the engine 4 from the openings (the intake port 7 and the exhaust port 8) causes an increase in ambient noise. For this reason, there is a need to provide openings on the upper and lower surfaces of the engine room 10 as much as possible so that fan noise and engine noise are not directly transmitted to the surrounding people. In that respect, in the configuration of the present embodiment, since the inflow from the radial direction (centripetal flow) and the outflow in the radial direction (centrifugal flow) of the axial flow fan 2 are compatible, the rotating shaft 2c of the axial flow fan 2 is achieved. This is convenient when an opening is provided in the upper part of the engine chamber 10 that is a side when viewed from the side, and contributes to noise reduction of the entire hydraulic excavator while suppressing overall pressure loss.

If the advance angle θ is too large, the centripetal flow on the suction side of the axial fan 2 and further the axial flow on the discharge side become strong, and even if it has the above-described configuration, the centrifugal flow on the downstream side is increased. It becomes difficult to realize. Further, the value of the fan noise varies depending on the value of the advance angle θ, and the air volume is also affected. Therefore, the inventors conducted the following simulation analysis in order to obtain a preferable angle range of the advance angle θ.

First, the inventors conducted a simulation analysis of noise when the design air volume (100% Q) was achieved. In the case where the static pressure of the axial fan 2 is low, it is necessary to increase the fan rotation speed in order to obtain the design air volume (100% Q) necessary for cooling. When converted into a noise change due to an increase in the number of rotations to achieve the design air volume, it becomes as shown in FIG. FIG. 5 shows the forward angle θ = 0 ° as a reference. If possible, we want to design the lowest noise that can be obtained (that is, near θ = 0 °). However, an increase of 3 dB in noise (twice the energy of sound) is the level difference at which the increase in noise begins to be perceived by the human ear. It is said that an increase in noise up to this point is acceptable. From this point of view, if the advance angle θ is about 25 ° or less, it is possible to achieve the lowest level of noise perceived by humans. That is, it was found from this simulation analysis that the upper limit of the advance angle θ that can suppress the noise to +3 dB or less is 25 °.

Next, the inventors conducted a simulation analysis of how much the air flow decreases when the pressure loss (flow path resistance) increases by 30% from the design time. The result is shown in FIG. The construction machine is in an operating environment in which dust and dirt accumulate on the heat exchanger due to the operating environment, and the flow resistance gradually increases as an axial fan. Actually, after a certain amount of time of operation, the heat exchanger and filter are cleaned to remove clogging, and the increase in flow resistance is suppressed. In other words, it is desirable to use an axial fan with as little airflow reduction as possible even if the flow path resistance increases. Therefore, assuming that a 10% reduction in the air volume is an allowable lower limit, it is desirable from FIG. 6 that the advance angle θ is about 5 ° or more and about 40 ° or less.

From the above simulation analysis results, it was found that the advance angle θ as a threshold value satisfying both design requirements is 5 ° or more and 25 ° or less. Therefore, in the axial fan 2 according to the present embodiment, the advancing angle θ of the blade 2a is set to 5 ° to 25 °.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a side sectional view of the engine chamber of the hydraulic excavator according to the second embodiment. In addition, about the same structure as 1st Example among 2nd Example, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In this embodiment, the axial fan 2 is provided separately from the engine 4, the heat exchanger 1 is disposed on the downstream side of the axial fan 2, and the intake port 7 is the engine on the upstream side of the axial fan 2. The upper and lower wall surfaces of the chamber 10 are disposed on the side surfaces as viewed from the rotating shaft 2 c of the axial fan 2. The axial fan 2 is directly connected to the hydraulic motor 11 and is driven thereby. A fan ring 3 is installed around the axial fan 2 as in the first embodiment.

When the axial fan 2 rotates, air flows into the engine compartment 10 from the intake port 7. After passing through the axial fan 2, the air exchanges heat in the heat exchanger 1 and is discharged to the outside through the exhaust ports 8 located on the upper and lower sides on the downstream side.

Also in the configuration of the second embodiment, the centripetal flow on the upstream side of the axial fan 2 and the centrifugal flow on the downstream side are compatible. For this reason, air flows in smoothly from the air inlet 7 provided on the side as viewed from the rotating shaft 2c. In addition, when the flow that flows out of the axial fan 2 enters the heat exchanger 1, air enters the end portion of the heat exchanger 1, so that effective heat exchange can be realized. Since the intake port 7 and the exhaust port 8 are on the upper surface and the lower surface of the engine compartment 10, the noise of the axial fan 2 and the motor 11 does not directly reach the surrounding human ears, so that the noise around the hydraulic excavator is reduced. Can contribute.

Although the effects of the present invention have been described with the above embodiments, the present invention is not necessarily limited thereto. In the present invention, for example, the fan driving method and the type of heat exchanger to be used are not limited, and the effect can be expected in construction machines other than hydraulic excavators.

1 Heat exchanger 2 Axial fan 2a Wing (blade piece)
2c Rotating shaft (axis)
2d Rear edge 2e Outer peripheral edge 2g Front edge 3 Fan ring 3a Suction side R-shaped part 3b Discharge side R-shaped part 4 Engine (structure)
P First intersection point Q Second intersection point W Width of discharge-side R-shaped portion θ Advance angle

Claims

An axial fan having a plurality of blades and rotating about an axis; a fan ring arranged around the axial fan to guide an air flow to the axial fan; and an air flow from the axial fan In a construction machine comprising a heat exchanger disposed upstream or downstream of a flow and a structure disposed downstream of the air flow from the axial fan,
The fan ring has a suction side R-shaped portion that reduces the flow path on the suction side, and a discharge-side R-shaped portion that expands the flow path on the discharge side,
The blade piece is formed to have a front edge, a rear edge, and an outer peripheral edge, and is inclined in a forward angle θ from the axial center toward the rotation direction, and attached in a posture inclined forward to the suction side,
In a state where the axial fan is attached to the inside of the fan ring, a first intersection where the trailing edge of the blade piece and the outer peripheral edge intersect is located within the range of the width of the discharge side R-shaped portion. Construction machinery characterized by
In the description of claim 1,
The advancing angle θ is in the range of 5 ° to 25 °.
In the description of claim 2,
A construction machine characterized in that a second intersection point where the front edge and the outer peripheral edge of the wing piece intersect is at a position protruding from the suction side R-shaped portion to the upstream side of the air flow.