Air conditioner for construction machine

An air conditioner for a construction machine which can ensure the required durability of a supply line and a discharge line, and which can reduce manufacturing costs. The air conditioner has an exterior unit outside the cab and an interior unit on the floor of the cab, the interior unit including an expansion valve disposed at a position above an upper surface of a floor plate of a cab. The expansion valve is connected to an outer device of the air conditioner by a supply line and a discharge line extending along the bottom surface of the floor plate, and bent upward at a passage which is formed in the floor plate. The supply line and the discharge line are fixed by a latching means such as a p-clip disposed in proximity to the passage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of International Patent Application No. PCT/EP2015/077447 filed Nov. 25, 2015, which claims priority to Japanese Patent Application No. 2014-237437 filed Nov. 25, 2014, both of which are incorporated by reference herein in their entireties for all purposes.

TECHNICAL FIELD

The present invention relates to an air conditioner for a construction machine having a cab with a lower part closed with a floor plate.

BACKGROUND ART

Generally, a hydraulic excavator, a typical example of a construction machine, is roughly configured with a mobile lower traveling body, an upper swivel body mounted on the lower traveling body so as to be able to swivel freely, and a working arm device connected to the upper swivel body so as to be able to move up and down freely. The upper swivel body has a swiveling frame configuring the framing structure thereof, and the swiveling frame is provided with a cab in which an operator rides, an equipment room where various equipment such as an engine and radiator are stored, a counterweight for balancing the weight of a load with respect to the working arm device, and the like.

Most of these hydraulic excavators are usually equipped with an air conditioner for a cab which is configured with an exterior unit disposed outside the cab and an interior unit disposed inside the cab. The exterior unit has a compressor for compressing a refrigerant, a condenser for condensing the refrigerant compressed by the compressor, and a receiver for storing the refrigerant condensed by the condenser. The interior unit, on the other hand, has an expansion valve that expands the refrigerant transferred from the receiver, and an evaporator that evaporates the refrigerant expanded by the expansion valve.

The receiver of the exterior unit and the expansion valve of the interior unit are connected to each other by a supply pipe, so that the refrigerant for cooling the inside is supplied from the receiver of the exterior unit to the expansion valve of the interior unit through the supply pipe. The expansion valve of the interior unit and the compressor of the exterior unit are connected to each other by a discharge pipe, so that the refrigerant circulates between the interior unit and the exterior unit (see Patent Literature 1, for example).

DISCLOSURE OF THE INVENTION

Incidentally, this type of interior unit of the air conditioner is usually provided at a rear portion of an upper surface of a floor plate of the cab. The expansion valve of the interior unit is normally provided, in a protruding manner, at a lower end of the interior unit. Therefore, an opening corresponding to the expansion valve is formed in the floor plate. The expansion valve is provided on the inside of the opening of the floor plate, and the supply pipe and the discharge pipe are connected to the expansion valve by a block flange, which is made of an appropriate metal for the purpose of ensuring necessary durability of these pipes.

The present invention was contrived in view of these facts, and a main technical object thereof is to provide an air conditioner for a construction machine that enables acquisition of necessary durability of its supply pipe and discharge pipe without having a block flange between the expansion valve and these pipes, as well as a reduction in manufacturing cost of the construction machine.

As an air conditioner for a construction machine that can achieve the foregoing technical object, the present invention provides an air conditioner for a construction machine having a cab with a lower portion closed with a floor plate, the air conditioner being configured with: an exterior unit disposed outside the cab; and an interior unit disposed inside the cab, wherein the exterior unit includes a compressor for compressing a refrigerant, and a condenser for condensing the refrigerant compressed by the compressor, the interior unit includes an expansion valve for expanding the refrigerant condensed by the condenser, and an evaporator for evaporating the refrigerant expanded by the expansion valve, the expansion valve being disposed at a position above an upper surface of the floor plate and connected to the exterior unit by a supply pipe for supplying the refrigerant condensed by the condenser from the exterior unit to the interior unit and a discharge pipe for discharging the refrigerant evaporated by the evaporator from the interior unit to the exterior unit, the floor plate has a passage opening through which the supply pipe and the discharge pipe pass, the supply pipe and the discharge pipe extending under the floor plate along a bottom surface of the floor plate, bending upward at the passage opening and passing through the passage opening, and the floor plate is provided with latching means in proximity to the passage opening to latch the supply pipe and the discharge pipe.

According to the air conditioner for a construction machine, which is provided by the present invention, the expansion valve is disposed at a position above the upper surface of the floor plate of the cab and connected to the exterior unit by the supply pipe for supplying the refrigerant condensed by the condenser from the exterior unit to the interior unit and the discharge pipe for discharging the refrigerant evaporated by the evaporator from the interior unit to the exterior unit. The passage opening through which the supply pipe and the discharge pipe pass is formed in the floor plate. The supply pipe and the discharge pipe extend under the floor plate along the bottom surface of the floor plate, bend upward at the passage opening and pass through the passage opening. The floor plate is provided with the latching means in proximity to the passage opening to latch the supply pipe and the discharge pipe. According to this configuration, without having a block flange between the expansion valve and the supply and discharge pipes, necessary durability of the supply pipe and the discharge pipe can be ensured. Moreover, the manufacturing cost of the construction machine can be reduced because such a block flange is not required.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of an air conditioner for a construction machine according to the present invention is now described hereinafter with a hydraulic excavator, a typical construction machine, and with reference to the accompanying drawings.

The hydraulic excavator is described with reference toFIG. 1first. The hydraulic excavator, the entire of which is shown with a reference numeral2, is roughly configured with a mobile lower traveling body4, an upper swivel body6mounted on the lower traveling body4so as to be able to swivel freely, and a working arm device8connected to the upper swivel body6so as to be able to move up and down freely. At an excavation of soil and the like, the working arm device8of the hydraulic excavator2is moved up and down and the upper swivel body6swivels with respect to the lower traveling body4, thereby excavating soil and the like.

The working arm device8is roughly configured with a boom10connected to the front side of the upper swivel body6so as to be able to move up and down freely, an arm12connected to a tip end of the boom10so as to be able to swing freely, an operating tool14connected to a tip end of the arm12so as to be able to rotate freely, a pair of right and left boom cylinders16for moving the boom10up and down, an arm cylinder18for swinging the arm12, and an operating tool cylinder20for rotating the operating tool14.

The cab24has a framing structure configured with a plurality of pillars made of steel pipes and a beam that connects the plurality of pillars made of steel pipes. The frame of the cab24is configured such that a lower portion thereof is closed with a floor plate30made of a steel plate, peripheral side surfaces of the same are covered with a door32, a window34and the like, and an upper surface of the same is covered with a roof material having a window. A driver's seat for seating the operator, a plurality of operation devices for operating the hydraulic excavator2, a display device for displaying machine information necessary for the operator, and the like are provided inside the cab24.

As shown inFIG. 2, an engine36functioning as a driving source, a radiator38for cooling an engine coolant, a hydraulic pump functioning as a hydraulic supply source, and various other equipment are disposed in the equipment room26. The radiator38is disposed at one side in a drive axis direction of the engine36, and a cooling fan is connected to one side of the drive axis of the engine36, whereby the engine coolant inside the radiator38is cooled by an airflow generated by the cooling fan. Also, the hydraulic pump is connected to the other side of the drive axis of the engine36and driven by the engine36. The pressure oil that is ejected from the hydraulic pump is supplied to a hydraulic actuator, such as the boom cylinder16, via a control valve or the like.

The present invention is further described with reference toFIGS. 2 and 3. The hydraulic excavator2is equipped with an air conditioner for the cab24, in which the air conditioner is configured with an exterior unit disposed inside the equipment room26and an interior unit disposed inside the cab24. The exterior unit has a compressor40for compressing a refrigerant, a condenser42for condensing the refrigerant compressed by the compressor40, and a receiver44for storing the refrigerant condensed by the condenser42. The compressor40and the condenser42are connected to each other by a pipe, and the condenser42and the receiver44, too, are connected to each other by a pipe. The pipes are each configured with a hose made mainly out of a rubber material and a coupling that is clamped to each end of the hose and made of an appropriate metal such as aluminum or copper, wherein the couplings are screwed to the equipment such as the compressor40, thereby connecting the pipes. The compressor40is disposed in the engine36and driven by the engine36. As shown inFIG. 3, the condenser42is provided inside the equipment room26along with the radiator38and cools and condenses the high-temperature, high-pressure refrigerant transferred from the compressor40. The condenser42has a small tube for allowing the passage of the refrigerant and a plurality of radiation fins disposed in the small tube, wherein the refrigerant inside the condenser42is cooled by the airflow generated by the cooling fan of the engine36, along with the engine coolant inside the radiator38. The receiver44, disposed on the side of the radiator38, stores the refrigerant transferred from the condenser42and removes the moisture content of the refrigerant.

The interior unit is disposed at a rear portion of an upper surface of the floor plate30of the cab24and has a casing46that is provided internally with an expansion valve48for expanding the high-pressure liquid refrigerant transferred from the receiver44, an evaporator50for evaporating the refrigerant expanded by the expansion valve48, and the like. The expansion valve48is disposed at a position above the upper surface of the floor plate30of the cab24and attached to the casing46. The expansion valve48is connected to the receiver44by a supply pipe52that supplies, from the exterior unit to the interior unit, the refrigerant condensed by the condenser42and stored in the receiver44. The expansion valve48is also connected to the compressor40by a discharge pipe54that discharges the refrigerant evaporated by the evaporator50from the interior unit to the exterior unit. The supply pipe52and the discharge pipe54are each configured with a hose made mainly out of a rubber material and a coupling that is clamped to each end of the hose and made of an appropriate metal such as aluminum or copper, wherein the couplings are screwed to the equipment such as the expansion valve48, thereby connecting the pipes. The refrigerant that is transferred from the receiver44to the expansion valve48through the supply pipe52is sprayed into the evaporator50in the form of low-pressure mist by the expansion valve48. Furthermore, in the evaporator50the refrigerant absorbs the heat of air taken in from the outside the cab24or air taken in from the inside of the cab24as vaporization heat, thereby cooling the air. A blower of the interior unit releases the resultant cooled air into the cab24through a duct disposed inside the cab24. As a result, the inside of the cab24is cooled. The refrigerant that is evaporated by the evaporator50and absorbs the heat of the air is transferred from the expansion valve48to the compressor40through the discharge pipe54.

As shown inFIG. 4, a passage opening30athrough which the supply pipe52and the discharge pipe54pass is formed in the floor plate30of the cab24. The supply pipe52and the discharge pipe54extend under the floor plate30along a bottom surface of the floor plate30, bend upward at the passage opening30aand pass through the passage opening30a. The supply pipe52and the discharge pipe54are then connected to the expansion valve48at the position above the upper surface of the floor plate30. The bottom surface of the floor plate30is provided with latching means56in proximity to the passage opening30a, and the supply pipe52and the discharge pipe54are latched by the latching means56. The latching means56is configured with, for example, a P-clip or the like that is tightened to the bottom surface of the floor plate30by bolts.

The effects of the foregoing air conditioner for the hydraulic excavator2shown inFIGS. 1 to 4are now described. In the air conditioner according to the present invention, the expansion valve48is disposed at a position above the upper surface of the floor plate30of the cab24and connected to the exterior unit by the supply pipe52for supplying the refrigerant condensed at the condenser42from the exterior unit to the interior unit and the discharge pipe54for discharging the refrigerant evaporated at the evaporator50from the interior unit to the exterior unit. In addition, the passage opening30athrough which the supply pipe52and the discharge pipe54pass is formed in the floor plate30, and the supply pipe52and the discharge pipe54extend under the floor plate30along the bottom surface of the floor plate30, bend upward at the passage opening30aand pass through the passage opening30a. Furthermore, the floor plate30is provided with the latching means56in proximity to the passage opening30a, and the supply pipe52and the discharge pipe54are latched by the latching means56. According to such a configuration, without having a block flange between the expansion valve48and the supply and discharge pipes52and54, necessary durability of the supply pipe52and the discharge pipe54can be ensured. Moreover, the manufacturing cost of the construction machine can be reduced because such a block flange is not required.

In the air conditioner according to the present invention, because the supply pipe52and the discharge pipe54bend upward at the passage opening30aand pass through the passage opening30a, the distance of protrusion of the bent portions of the supply pipe52and the discharge pipe54from the bottom surface of the floor plate30is reduced. This configuration prevents the supply pipe52and the discharge pipe54from interfering with the equipment and members under the floor plate30when vibrations and the like occur as a result of the activation of the hydraulic excavator2, preventing interference-related damage.

It should be noted that the foregoing embodiment is an example of the present invention. The present invention is not limited to the foregoing configuration and can be modified in various ways. For instance, although the embodiment has described an example in which the compressor is driven by the engine, the compressor may be driven electrically. In such a case, the compressor does not have to be disposed in the engine as described in the embodiment and can be disposed at an appropriate position in the upper swivel body.

Also, although the embodiment has described an example in which the condenser is provided inside the equipment room along with the radiator and the refrigerant in the condenser is cooled by the cooling fan of the engine along with the engine coolant of the radiator, the condenser itself may have an electrically driven fan for cooling the refrigerant inside the condenser. In this case, the condenser does not have to be disposed inside the equipment room as described in the embodiment and can be disposed at an appropriate position in the upper swivel body.

The embodiment has also described an example in which the condenser and the receiver are separate units and connected to each other by a pipe. However, the condenser and the receiver may be integrated into a subcooling condenser. In this case, the expansion valve is connected to the subcooling condenser by a supply pipe.