Hydraulic excavator

A hydraulic excavator is provided which can allow the cooling device to be arranged in proximity to a rear wall of a cab. The rear wall of the cab has an upright wall part extending in the vertical direction and an inclined wall part inclined to the rear upper side with respect to the upright wall part. The outer surface of an oil cooler has a front surface facing the upright wall part and extending in the vertical direction and an inclined surface inclined to the rear upper side with respect to the front surface. The upper edge of the front surface is arranged below the height position of the other edge of the inclined wall part. An angle formed by the upright wall part and the inclined wall part is more than or equal to an angle formed by the front surface and the inclined surface.

TECHNICAL FIELD

The present invention relates to a hydraulic excavator, and particularly to a hydraulic excavator having a cooling device.

BACKGROUND ART

Conventionally, a hydraulic excavator includes various kinds of cooling devices, such as a radiator which cools engine cooling water, an oil cooler which cools a hydraulic fluid supplied to a hydraulic actuator, and an intercooler which cools compressed air supplied to an engine. Japanese Patent Laying-Open No. 2001-246943 (PTD 1) discloses a configuration in which a lower part of a rear wall of a cab is formed into a shape retracted into the cab to provide space on the rear side of the rear wall, a radiator and an oil cooler have a rectangular shape when viewed in side view, and a baffle plate is provided between the lower part of the rear wall of the cab and the side surface of the radiator.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

In order to avoid contact with an obstacle located backward at the time of revolving, a hydraulic excavator is required to have a smaller engine compartment and reduced space between a cooling device arranged on the rear side of the rear wall of a cab and the rear wall. However, if the cooling device having a rectangular shape when viewed in side view disclosed in the above-described publication is moved forward so as to approach the rear wall of the cab, the cooling device will interfere with an inclination of the rear wall of the cab. To prevent interference with the rear wall of the cab, it is necessary to reduce the entire height of the cooling device. In this case, however, a core part of the cooling device will be decreased in area, resulting in degraded performance of the cooling device.

When the cooling device has a rectangular shape when viewed in side view and in the case where a sealing material is present between the rear wall of the cab and the outer surface of the cooling device, corner portions of the cooling device are brought into line contact with the sealing material to cause stress concentration, which damages the sealing material.

The present invention was made in view of the above-described problem and has an object to provide a hydraulic excavator that can maintain performance of a cooling device, allows the cooling device to be arranged in proximity to the rear wall of a cab, and further, can suppress damage to a sealing material.

Solution to Problem

A hydraulic excavator of the present invention includes a cab having a rear wall, and a cooling device arranged on a rear side of the rear wall. The rear wall has an upright wall part and an inclined wall part. The upright wall part extends in the vertical direction. The inclined wall part is connected to an upper edge of the upright wall part and is inclined to a rear upper side with respect to the upper edge of the upright wall part. An outer surface of the cooling device has a front surface and an inclined surface. The front surface faces the upright wall part and extends in the vertical direction. The inclined surface is connected to an upper edge of the front surface and is inclined to the rear upper side with respect to the upper edge of the front surface. The inclined wall part has one edge connected to the upright wall part and the other edge opposite to the one edge. The upper edge of the front surface is arranged below a height position of the other edge. The upright wall part and the inclined wall part form an angle more than or equal to an angle formed by the front surface and the inclined surface.

According to the hydraulic excavator of the present invention, interference between the rear wall of the cab and the cooling device can be suppressed. Accordingly, the cooling device can be arranged in proximity to the rear wall. Therefore, a hydraulic excavator can be achieved which allows the cooling device to be arranged in proximity to the rear wall of the cab while maintaining cooling performance of the cooling device. In the case where a sealing material is present between the rear wall of the cab and the outer surface of the cooling device, the sealing material can be brought into surface contact with the inclined surface. Therefore, stress concentration can be relieved, and damage to the sealing material can be suppressed.

In the above-described hydraulic excavator, the upper edge of the front surface is positioned between a bisector of the angle formed by the upright wall part and the inclined wall part and a height position of the upper edge of the upright wall part, in the vertical direction. Then, contact between the cooling device and the rear wall can be prevented, while ensuring space to be filled with the sealing material between the cooling device and the rear wall of the cab.

In the above-described hydraulic excavator, the inclined surface has a portion extending in parallel to the inclined wall part. Accordingly, the cooling device can be arranged in proximity to both the upright wall part and the inclined wall part of the rear wall. Therefore, the distance between the rear wall and the cooling device can be made smaller.

The above-described hydraulic excavator further includes a work implement and a hydraulic actuator driving the work implement. The cooling device is an oil cooler cooling a hydraulic fluid supplied to the hydraulic actuator. Accordingly, the oil cooler can be arranged in proximity to the rear wall of the cab, while suppressing interference between the rear wall of the cab and the oil cooler and maintaining cooling performance of a hydraulic fluid by the oil cooler.

In the above-described hydraulic excavator, the oil cooler includes a core part cooling the hydraulic fluid passing therethrough and an upper tank arranged over the core part. The front surface and the inclined surface constitute an outer surface of the upper tank. A cross section of the upper tank perpendicular to a front-back direction has a rectangular outer shape. Then, since the outer surface of the upper tank is provided with the inclined surface, the shape of the core part can be kept, and the dimensions of the core part can be maintained without the need to decrease the dimension in the height direction of the core part for preventing interference between the oil cooler and the rear wall. Therefore, cooling performance of a hydraulic fluid in the core part can be ensured. When the upper tank is formed into a shape having a rectangular cross section, it will be easier to ensure the capacity of the upper tank even if the upper tank is provided with an inclined surface.

The above-described hydraulic excavator further includes a second cooling device arranged on the rear side of the cooling device. The uppermost surface of the second cooling device is arranged at a position higher than the uppermost surface of the cooling device. Then, the dimension in the height direction of the second cooling device can be increased as compared with the cooling device so as to conform to the inclination of the inclined wall part of the rear wall. Accordingly, the second cooling device can be increased in cooling capacity.

The above-described hydraulic excavator further includes a sealing material provided between the rear wall and the outer surface of the cooling device. Because the outer surface of the cooling device has an inclined surface, the sealing material can be brought into surface contact with the inclined surface. Accordingly, stress concentration can be relieved, and damage to the sealing material can be suppressed.

Advantageous Effects of Invention

According to the present invention as described above, a hydraulic excavator can be achieved which can maintain performance of a cooling device, allows the cooling device to be arranged in proximity to a rear wall of a cab, and further, can suppress damage to a sealing material.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Firstly, a configuration of a hydraulic excavator to which the idea of the present invention is applicable will be described.

FIG. 1is a side view showing a configuration of a hydraulic excavator according to one embodiment of the present invention. A hydraulic excavator1according to the present embodiment mainly includes a lower traveling unit2, an upper revolving unit3, a work implement4, a counter weight5, a cooling unit6, and a cab10, as shown inFIG. 1. Lower traveling unit2and upper revolving unit3constitute a work vehicle main body.

Lower traveling unit2has a pair of crawler belts P wound around both the left and right ends in the traveling direction. Lower traveling unit2is configured to be self-propelled by rotation of the pair of crawler belts P.

Upper revolving unit3is mounted on lower traveling unit2revolvably in any direction. Upper revolving unit3includes a cab10, which is a driver's cabin for an operator of hydraulic excavator1to get on and off, at the front left side. Upper revolving unit3includes an engine compartment for accommodating an engine and counter weight5on the rear side.

It should be noted that, in the present embodiment, when an operator is seated in cab10, the front side (front surface side) of the operator will be assumed as the front side of upper revolving unit3, the opposite side thereto, namely, the rear side of the operator will be assumed as the rear side of upper revolving unit3, the left side of the seated operator as the left side of upper revolving unit3, and the right side of the seated operator as the right side of upper revolving unit3. In the following description, back and forth, right and left of upper revolving unit3shall be in agreement with those of hydraulic excavator1. In the drawings which will be described below, the front-back direction is indicated by an arrow X in the drawings, the left-right direction by an arrow Y in the drawings, and the vertical direction by an arrow Z in the drawings.

Work implement4for performing operation such as earth excavation is pivotally supported by upper revolving unit3so as to be swingable in the upward and downward directions. Work implement4has a boom4amounted swingably in the upward and downward directions at a substantially central portion on the front side of upper revolving unit3, an arm4bmounted swingably in the forward and backward directions at a leading end portion of boom4a, and a bucket4cmounted swingably in the forward and backward directions at a leading end portion of arm4b. Boom4a, arm4band bucket4care each configured to be swingably driven by a hydraulic cylinder38.

Work implement4is provided relative to cab10on the right side which is one lateral side of cab10such that the leading end portion of work implement4is visible to the operator in cab10. Cab10is arranged on a lateral side of a mounting portion of work implement4. It should be noted that the arrangement of cab10and work implement4is not limited to the example shown inFIG. 1. For example, work implement4may be arranged on the front side of upper revolving unit3, and cab10may be provided on the rear side of work implement4(substantially at the center of upper revolving unit3).

Counter weight5is a weight arranged at the rear of upper revolving unit3in order to achieve balance of the vehicle body at the time of digging and the like. Cooling unit6is housed in an engine compartment at the rear of upper revolving unit3. The configuration of cooling unit6will be described later in detail.

FIG. 2is a plan view of upper revolving unit3constituting hydraulic excavator1ofFIG. 1.FIG. 3is a perspective view of upper revolving unit3constituting hydraulic excavator1ofFIG. 1. Referring toFIGS. 2 and 3, the engine compartment at the backside of upper revolving unit3is covered from above with an upper plate15, and is covered laterally with an upper lateral plate16which is an upper-side lateral plate and a lower lateral plate17which is a lower-side lateral plate. Upper plate15defines the upper outer shape of the engine compartment. Upper lateral plate16and lower lateral plate17define the outer shape on the right, left and rear sides of the engine compartment. Upper lateral plate16has formed therein air vents18through which the inside and the outside of the engine compartment communicate with each other. Lower lateral plate17has formed therein air vents19through which the inside and the outside of the engine compartment communicate with each other. Air vents18and19are formed on the rear left side of upper revolving unit3.

As shown inFIG. 3, upper revolving unit3includes a revolving frame12. Revolving frame12is arranged above lower traveling unit2shown inFIG. 1, and is mounted revolvably relative to lower traveling unit2. Work implement4, cab10, counter weight5, and cooling unit6are mounted on revolving frame12, and are arranged on the upper surface of revolving frame12.

A center bracket13supporting the base end section of work implement4is provided at the central portion of the front end of revolving frame12. Counter weight5is arranged to cover the rear side of cooling unit6.

FIG. 4is a plan view showing a configuration in the engine compartment mounted on revolving frame12. Referring toFIG. 4, cooling unit6, an engine7and a fan8are housed in the engine compartment defined by being covered from above and laterally with upper plate15, upper lateral plate16and lower lateral plate17.

In the engine compartment, cooling unit6, fan8and engine7are arranged in the presented order from the left side to the right side. Cooling unit6is arranged on the left side with respect to fan8, that is, on the side closer to air vents18and19. Engine7is arranged on the right side with respect to fan8, that is, on the side away from air vents18and19. Fan8is rotationally driven by engine7to produce an air flow passing through the engine compartment.

Cooling unit6is mounted on revolving frame12so as to overlap cab10when viewed in plan view. Cooling unit6is formed to include an oil cooler60, an intercooler70and a radiator80. Oil cooler60is a cooling device intended to cool a hydraulic fluid supplied to various kinds of hydraulic actuators mounted on hydraulic excavator1, such as hydraulic cylinder38. Intercooler70is a cooling device intended to cool compressed air supplied to engine7. Radiator80is a cooling device intended to cool cooling water of engine7. Oil cooler60, intercooler70and radiator80are arranged in the presented order from the front side to the rear side.

FIG. 5is a rear view showing a configuration in the engine compartment mounted on revolving frame12. Blank arrows inFIG. 5indicate the air flow produced by fan8rotationally driven by engine7.

When fan8is rotationally driven, air flows into the engine compartment from the outside of upper revolving unit3through air vents18and19formed in upper lateral plate16and lower lateral plate17, respectively. Air flows passing through cooling unit6, fan8and engine7in the presented order. Cooling unit6is arranged on the upstream side of the air flow with respect to fan8. Engine7is arranged on the downstream side of the air flow with respect to fan8. Air further passes through the air vents formed in the lower part of upper revolving unit3, and flows out of the engine compartment to the outside of upper revolving unit3.

FIG. 6is a hydraulic circuit diagram applied to hydraulic excavator1ofFIG. 1. In the hydraulic system of the present embodiment shown inFIG. 6, a hydraulic pump31is driven by engine7. Hydraulic pump31serves as a drive source for driving a hydraulic actuator, such as hydraulic cylinder38, for driving work implement4shown inFIG. 1. A hydraulic fluid discharged from hydraulic pump31is supplied to hydraulic cylinder38through a pilot switching valve37. The hydraulic fluid supplied to hydraulic cylinder38is discharged to a tank35through pilot switching valve37. Tank35stores the hydraulic fluid therein.

Pilot switching valve37controls supply and discharge of the hydraulic fluid to hydraulic cylinder38. Pilot switching valve37has a pair of pilot control ports p1 and p2. Pilot switching valve37is controlled by the hydraulic fluid having a predetermined pilot pressure being supplied to each of pilot control ports p1 and p2.

The pilot pressure applied to pilot switching valve37is controlled by the operation of a control lever device41. Control lever device41has a control lever44operated by an operator, a first pilot pressure control valve41A and a second pilot pressure control valve41B. Pilot pressure control valves41A and41B for controlling driving of hydraulic cylinder38are connected to control lever44.

First pilot pressure control valve41A has a first pump port X1, a first tank port Y1 and a first supply/discharge port Z1. First pump port X1 is connected to a pump channel51. First tank port Y1 is connected to a tank channel52. Pump channel51and tank channel52are connected to tank35storing the hydraulic fluid. Hydraulic pump31is provided in pump channel51. First supply/discharge port Z1 is connected to a first pilot tube passage53.

First pilot pressure control valve41A is switched between an output state and a discharging state in accordance with the operation of control lever44. In the output state, first pilot pressure control valve41A causes first pump port X1 and first supply/discharge port Z1 to communicate with each other, so that a hydraulic fluid is output to first pilot tube passage53through first supply/discharge port Z1 at a pressure in accordance with the amount of operation of control lever44. In the discharging state, first pilot pressure control valve41A causes first tank port Y1 and first supply/discharge port Z1 to communicate with each other.

Second pilot pressure control valve41B has a second pump port X2, a second tank port Y2 and a second supply/discharge port Z2. Second pump port X2 is connected to pump channel51. Second tank port Y2 is connected to tank channel52. Second supply/discharge port Z2 is connected to a second pilot tube passage54.

Second pilot pressure control valve41B is switched between an output state and a discharging state in accordance with the operation of control lever44. In the output state, second pilot pressure control valve41B causes second pump port X2 and second supply/discharge port Z2 to communicate with each other, so that a hydraulic fluid is output to second pilot tube passage54through second supply/discharge port Z2 at a pressure in accordance with the amount of operation of control lever44. In the discharging state, second pilot pressure control valve41B causes second tank port Y2 and second supply/discharge port Z2 to communicate with each other.

First pilot pressure control valve41A and second pilot pressure control valve41B are paired, and correspond to operating directions of control lever44opposite to each other. For example, first pilot pressure control valve41A corresponds to an inclined operation of control lever44in the forward direction, and second pilot pressure control valve41B corresponds to an inclined operation of control lever44in the backward direction. First pilot pressure control valve41A and second pilot pressure control valve41B are selected alternatively by the operation of control lever44. That is, when first pilot pressure control valve41A is in the output state, second pilot pressure control valve41B is in the discharging state. When first pilot pressure control valve41A is in the discharging state, second pilot pressure control valve41B is in the output state.

First pilot pressure control valve41A controls supply and discharge of the hydraulic fluid to first pilot control port p1 with pilot switching valve37. Second pilot pressure control valve41B controls supply and discharge of the hydraulic fluid to second pilot control port p2 with pilot switching valve37. In accordance with the operation of control lever44, supply and discharge of the hydraulic fluid to and from hydraulic cylinder38is controlled, and extension and contraction of hydraulic cylinder38is controlled. Accordingly, the operation of work implement4is controlled in accordance with the operation of control lever44.

Oil cooler60described above is provided in tank channel52serving as a channel of the hydraulic fluid flowing towards tank35. Oil cooler60cools the hydraulic fluid discharged through first pilot pressure control valve41A or second pilot pressure control valve41B and flowing back to tank35. Oil cooler60also cools the hydraulic fluid discharged through pilot switching valve37and flowing back to tank35. As shown inFIG. 6, oil cooler60has a function of cooling the hydraulic fluid supplied to hydraulic cylinder38.

FIG. 7is a side view showing a configuration of and around cab10in hydraulic excavator1ofFIG. 1. As shown inFIG. 7, cab10has a rear wall20. Rear wall20has an upright wall part21extending in the vertical direction as indicated by an arrow Z inFIG. 7, and an inclined wall part22extending at an inclination with respect to the vertical direction. Upright wall part21and inclined wall part22are connected at a connecting portion23. Connecting portion23constitutes the upper edge of upright wall part21and constitutes the lower edge of inclined wall part22. Connecting portion23constitutes one edge of inclined wall part22that is connected to upright wall part21. Inclined wall part22has the other edge24on the opposite side of connecting portion23. Connecting portion23may be a portion obtained by bonding flat plate-like upright wall part21and flat plate-like inclined wall part22by welding or the like. Alternatively, connecting portion23may be a bent portion obtained by bending a piece of flat plate to form upright wall part21and inclined wall part22.

Inclined wall part22is connected to the upper edge of upright wall part21. Inclined wall part22is inclined with respect to the vertical direction so as to be directed toward the rear side with distance from connecting portion23. Inclined wall part22is inclined to the rear upper side with respect to the upper edge of upright wall part21extending in the vertical direction. Rear wall20has a bent shape when viewed in side view with upright wall part21and inclined wall part22being connected to each other at their edges. Cab10is formed in a shape with the lower part of rear wall20retracted into cab10.

Cooling unit6is arranged on the rear side of rear wall20of cab10. Oil cooler60, intercooler70and radiator80included in cooling unit6are arranged in the presented order from the front side to the rear side when viewed in side view. Oil cooler60is arranged below inclined wall part22of rear wall20. Oil cooler60is arranged in proximity to upright wall part21of rear wall20of cab10, and is arranged to overlap cab10when viewed in plan view.

Cooling unit6includes a case part91, an attachment plate92and a fuel cooler94. Case part91is a substantially box-shaped frame to which oil cooler60, intercooler70and radiator80are attached. Attachment plate92is attached to the upper parts of intercooler70and radiator80to integrate intercooler70and radiator80. Fuel cooler94is a cooling device for cooling fuel or the like not burnt in engine7, and is arranged at the lower part of cooling unit6over the side faces of oil cooler60, intercooler70and radiator80.

A sealing material30is provided between upright wall part21of rear wall20of cab10and oil cooler60. A baffle plate95is provided between inclined wall part22of rear wall20of cab10and oil cooler60. A sealing material is also provided between radiator80and counter weight5. These sealing material30and baffle plate95fill an air gap around cooling unit6. Therefore, an air flow that takes a shortcut through cooling unit6is suppressed.

FIG. 8is a perspective view of oil cooler60mounted on hydraulic excavator1ofFIG. 1. Referring toFIG. 8, oil cooler60includes a core part61, an upper tank62arranged over core part61, and a lower tank64arranged under core part61. Upper tank62has a connection port63to which an oil pipe constituting tank channel52shown inFIG. 6is connected. Lower tank64has a connection port65to which the oil pipe constituting tank channel52shown inFIG. 6is connected.

Core part61has a plurality of tubes of small diameter, each having an upper end connected to upper tank62and a lower end connected to lower tank64, and fins arranged between adjacent tubes. The hydraulic fluid flows into lower tank64through connection port65, and flows from lower tank64toward upper tank62through the tubes of core part61. The hydraulic fluid flowing through core part61is cooled by exchanging heat with air flowing through core part61in association with the driving of fan8. With the hydraulic fluid passing through core part61radiating heat to the air flow, oil cooler60cools the hydraulic fluid. The hydraulic fluid cooled in core part61is temporarily stored in upper tank62, and flows out of upper tank62through connection port63.

The outer surface of upper tank62has a front surface66and an inclined surface67. Inclined surface67is connected to the upper edge of front surface66, and is inclined to the rear upper side with respect to the upper edge of front surface66. Upper tank62has an outer shape obtained by collapsing a cylinder in the vertical direction as a whole. As compared with a cylinder, the deformation of the tubular shape of upper tank62is larger toward the opposite ends, with the result that inclined surface67is formed as the upper surface of upper tank62. Inclined surface67of the first embodiment has a curved surface shape curved to project upwardly.

FIG. 9is a side view showing a configuration of and around rear wall20of cab10in hydraulic excavator1ofFIG. 1. In the state shown inFIG. 9where oil cooler60is housed in the engine compartment, front surface66of upper tank62extends in the vertical direction, and faces upright wall part21of rear wall20of cab10. Inclined surface67of upper tank62faces inclined wall part22of rear wall20of cab10. In the side view shown inFIG. 9, front surface66and inclined surface67of upper tank62are connected to each other at a connecting portion68. Connecting portion68constitutes the upper edge of front surface66, and constitutes the lower edge of inclined surface67. Connecting portion68is arranged below the height position of other edge24of inclined wall part22.

Inclined surface67is connected to the upper edge of front surface66. Inclined surface67is inclined with respect to the vertical direction so as to be directed toward the rear side with distance from connecting portion68. Inclined surface67is inclined to the rear side with respect to front surface66extending in the vertical direction. Upper tank62has a bent outer shape when viewed in side view with front surface66and inclined surface67being connected to each other at their edges. Connecting portion68may be a portion obtained by bonding front surface66and inclined surface67by welding or the like.

Oil cooler60has an uppermost surface69positioned at the highest in the vertical direction. Intercooler70arranged on the rear side of oil cooler60has an uppermost surface79. Radiator80arranged on the rear side of intercooler70has an uppermost surface89. Uppermost surfaces79and89of intercooler70and radiator80are arranged at a higher position than the uppermost surface of oil cooler60in the vertical direction.

FIG. 10is a schematic view showing an arrangement of rear wall20of cab10and oil cooler60.FIG. 10schematically illustrates the outer shape and arrangement of rear wall20of cab10and oil cooler60when viewed in side view. Sealing material30and baffle plate95provided in the gap between oil cooler60and rear wall20are omitted from the illustration inFIG. 10for the purpose of simplification.

Upright wall part21of rear wall20has a surface21son the rear side. Inclined wall part22of rear wall20has a surface22son the rear side. Surface21sof upright wall part21and surface22sof inclined wall part22are connected to each other at a connecting portion23s. Surfaces21sand22shave a planar shape. Surfaces21sand22sintersect at connecting portion23s. When rear wall20is viewed in side view, the angle formed by surface21sof upright wall part21and surface22sof inclined wall part22is an angle α shown inFIG. 10.

When oil cooler60mounted in the engine compartment is viewed in side view, the angle formed by front surface66and inclined surface67of upper tank62is an angle β shown inFIG. 10. Rear wall20of cab10and upper tank62of oil cooler60are formed such that angle α formed by surface21sof upright wall part21and surface22sof inclined wall part22is more than or equal to angle β formed by front surface66and inclined surface67of upper tank62.

A straight line H indicated by a chain double-dashed line inFIG. 10shows a line passing through connecting portion23swhere surface21sand surface22sintersect with each other and extending in the horizontal direction perpendicular to the vertical direction. That is, straight line H indicates the height position of connecting portion23. A straight line B indicated by a chain double-dashed line inFIG. 10shows a bisector of angle α formed by surface21sof upright wall part21and surface22sof inclined wall part22. Connecting portion68between front surface66and inclined surface67of upper tank62is arranged between straight line B indicating the bisector of the angle (angle α) formed by upright wall part21and inclined wall part22and straight line H indicating the height position of the upper edge of upright wall part21, in the vertical direction. Straight lines H and B form an angle γ.

Next, the effects of the present embodiment will be described.

According to the present embodiment, rear wall20has upright wall part21and inclined wall part22, as shown inFIG. 10. Upright wall part21extends in the vertical direction. Inclined wall part22is connected to the upper edge of upright wall part21, and is inclined to the rear upper side with respect to connecting portion23positioned at the upper edge of upright wall part21. The outer surface of oil cooler60has front surface66and inclined surface67. Front surface66faces upright wall part21of rear wall20, and extends in the vertical direction. Inclined surface67is connected to the upper edge of front surface66, and is inclined to the rear upper side with respect to connecting portion68positioned at the upper edge of front surface66. Angle α formed by upright wall part21and inclined wall part22is more than or equal to angle β formed by front surface66and inclined surface67.

Inclined wall part22has connecting portion23as one edge connected to upright wall part21and other edge24on the opposite side of connecting portion23, as shown inFIG. 9. Connecting portion68which is an upper edge of front surface66of oil cooler60is arranged below the height position of other edge24.

Then, interference between inclined wall part22of rear wall20of cab10and oil cooler60can be suppressed. Therefore, oil cooler60can be arranged in proximity to rear wall20. Since inclined surface67is provided on the outer surface of upper tank62among the outer surfaces of oil cooler60, the rectangular shape of core part61when viewed in side view can be maintained. Moreover, the dimensions of core part61can be maintained without the need to decrease the dimension of core part61in the height direction for preventing interference between oil cooler60and rear wall20. Therefore, hydraulic excavator1can be achieved which allows the cooling device to be arranged in proximity to rear wall20of cab10while maintaining cooling performance of the hydraulic fluid in core part61.

Moreover, as shown inFIG. 10, connecting portion68positioned at the upper edge of front surface66of oil cooler60is located between straight line B indicating the bisector of angle α formed by upright wall part21and inclined wall part22and straight line H indicating the height position of the upper edge of upright wall part21, in the vertical direction. By defining the upper edge of front surface66of oil cooler60at a position higher than the bisector of angle α and below the upper edge of upright wall part21, contact between oil cooler60and rear wall20can be prevented while ensuring space to be filled with sealing material30between oil cooler60and rear wall20of cab10.

Since the height position of the upper edge of upright wall part21and the height position of the upper edge of front surface66of oil cooler60can be aligned by bringing the height position of the upper edge of front surface66of upper tank62close to the height position of the upper edge of upright wall part21, the position where the outer surface of oil cooler60is bent can be arranged in closer proximity to the position where rear wall20is bent. Therefore, the upper end of core part61of oil cooler60can be arranged at a higher position. The area of core part61can thereby be increased to further improve cooling performance of oil cooler60. From a viewpoint of maximizing the area of core part61, it is desirable to align the height position of the upper edge of the front surface with the upper edge of upright wall part21.

Moreover, as shown inFIG. 9, intercooler70and radiator80are arranged on the rear side of oil cooler60. Uppermost surface79of intercooler70and uppermost surface89of radiator80are arranged at a position higher than uppermost surface69of oil cooler60. Then, intercooler70and radiator80can be increased in dimension in the height direction as compared with oil cooler60, in accordance with the inclination of inclined wall part22of rear wall20. Accordingly, the core parts of intercooler70and radiator80can be increased in area, so that intercooler70and radiator80can be increased in cooling capacity.

Furthermore, as shown inFIG. 7, sealing material30is provided between rear wall20of cab10and front surface66and inclined surface67of oil cooler60. If oil cooler60has a rectangular shape when viewed in side view in the case where sealing material30is present between rear wall20of cab10and the outer surface of oil cooler60, the corner portions of oil cooler60may be brought into line contact with sealing material30to cause stress concentration, which may damage sealing material30. Because oil cooler60has inclined surface67, sealing material30can be brought into surface contact with inclined surface67. Accordingly, stress concentration can be relieved to suppress damage to sealing material30.

Second Embodiment

FIG. 11is a side view showing a configuration of and around rear wall20of cab10of a second embodiment.FIG. 12is a perspective view showing upper tank62of oil cooler60of the second embodiment.FIG. 13is a cross sectional view of upper tank62taken along the line XIII-XIII shown inFIG. 12.

Upper tank62of oil cooler60of the second embodiment has a trapezoidal outer shape when viewed in side view similar to that of the first embodiment. However, upper tank62of the second embodiment shown inFIG. 12has an outer surface formed by a combination of planes, while upper tank62of the first embodiment shown inFIG. 8has a shape obtained by collapsing a cylinder in the radial direction. That is, upper tank62of the second embodiment has front surface66, inclined surface67and uppermost surface69, all of which have a planar shape. Therefore, the sectional shape of upper tank62of the second embodiment has a rectangular outer shape as shown inFIG. 13. The cross section of upper tank62shown inFIG. 13corresponds to a cross section perpendicular to the front-back direction when oil cooler60is mounted in the engine compartment. Connecting portion68may be a bent portion obtained by bending a flat-plate-like material to form front surface66and inclined surface67.

In the second embodiment, the angle (angle α shown inFIG. 10) formed by surfaces21sand22sof upright wall part21and inclined wall part22of rear wall20of cab10is equal to the angle (angle13shown inFIG. 10) formed by front surface66and inclined surface67of upper tank62. Upper tank62of the second embodiment is formed such that inclined surface67is in parallel to surface22sof inclined wall part22. Inclined surface67of upper tank62of the second embodiment has a portion extending in parallel to inclined wall part22of rear wall20.

According to above-described hydraulic excavator1of the second embodiment, inclined surface67of upper tank62has a portion extending in parallel to inclined wall part22of rear wall20, as shown inFIG. 11. Accordingly, oil cooler60can be arranged close to both upright wall part21and inclined wall part22of rear wall20. Therefore, the shape of core part61can be kept to maintain cooling performance of oil cooler60, and the spacing between rear wall20and oil cooler60can be made even smaller.

If front surface66is in parallel to upright wall part21, and inclined surface67is in parallel to inclined wall part22, connecting portion68of oil cooler60can be arranged on the bisector of angle α shown inFIG. 10by arranging oil cooler60such that the distance between front surface66and upright wall part21is equal to the distance between inclined surface67and inclined wall part22. Therefore, positioning of oil cooler60with respect to rear wall20becomes easier, which can improve assembly of oil cooler60into the engine compartment.

Moreover, as shown inFIGS. 12 and 13, the cross section of upper tank62perpendicular to the front-back direction has a rectangular outer shape. Then, upper tank62can have a larger capacity than upper tank62of the first embodiment having an outer shape obtained by collapsing a cylinder. Therefore, it becomes even easier to ensure the capacity of upper tank62even when upper tank62is provided with inclined surface67. It should be noted that upper tank62of the first embodiment is desirable for its superiority in pressure resistance and easiness of manufacturing because of fewer welding spots.

It should be noted that the above description has provided an example in which the outer surface of upper tank62of oil cooler60has inclined surface67, and the angle formed by front surface66and inclined surface67among the outer surfaces of upper tank62is defined as compared with the angle formed by upright wall part21and inclined wall part22of rear wall20. The cooling device according to the present invention having an inclined surface is not limited to oil cooler60. That is, intercooler70or radiator80described in the embodiments may be arranged at the forefront of cooling unit6, and may be formed into a shape having an inclined surface. The idea of the present invention is suitably applicable to any cooling device that has a core part in which a medium is cooled by heat exchange between the medium flowing through the cooling device and air passing through the cooling device, and having tanks over and under the core part.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the claims not by the description above, and is intended to include any modification within the meaning and scope equivalent to the terms of the claims.

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