Heat source unit and air conditioner having the heat source unit

Abstract

A heat source unit for an air conditioner that includes a refrigerant circuit includes: an external housing; a cooling heat exchanger disposed in the external housing and that is connected to the refrigerant circuit; a controller that controls the valve; and a first temperature sensor disposed within the external housing. The external housing accommodates: a compressor connected to the refrigerant circuit; a heat source heat exchanger that is connected to the refrigerant circuit and that exchanges heat between a refrigerant circulating in the refrigerant circuit and a heat source; and an electric box. The electric box includes a top and a plurality of side walls; accommodates electrical components that control the air conditioner; and further includes an air passage that comprises an air inlet and an air outlet.

Claims

1. A heat source unit for an air conditioner that comprises a refrigerant circuit, the heat source unit comprising: an external housing that accommodates: a compressor connected to the refrigerant circuit; a heat source heat exchanger that is connected to the refrigerant circuit and that exchanges heat between a refrigerant circulating in the refrigerant circuit and a heat source; and an electric box that: includes a top and a plurality of side walls; accommodates electrical components; and further includes an air passage comprising an air inlet and an air outlet, wherein an air flow is induced through the air passage from the air inlet to the air outlet for cooling at least some of the electrical components; a cooling heat exchanger disposed in the external housing and that is connected to the refrigerant circuit, wherein the air flow flows through the cooling heat exchanger, and the cooling heat exchanger exchanges heat between the refrigerant and the air flow, and is connected to a bypass line disposed between a liquid refrigerant line and a gas suction line; a valve disposed on the bypass line upstream of the cooling heat exchanger; a controller that controls the valve; a first temperature sensor disposed within the external housing and out of the electric box and that measures air temperature at a location where the first temperature sensor is disposed; and a second temperature sensor disposed at an exit line between an exit of the cooling heat exchanger and a connection of the bypass line to the gas suction line, wherein the controller: switches the valve between an OFF-mode in which the valve is closed and an ON-mode in which the valve is opened based on the air temperature, determines a superheat degree of the refrigerant in the exit line based on a temperature detected by the second temperature sensor, switches between the ON-mode and the OFF-mode of the valve based on the superheat degree, and switches to the OFF-mode of the valve when the superheat degree falls below a predetermined value for a predetermined period of time.

2. The heat source unit according to claim 1, wherein the controller switches to the ON-mode when the air temperature is higher than a predetermined temperature.

3. The heat source unit according to claim 2, wherein the predetermined temperature is input or selected from a plurality of given predetermined temperatures.

4. The heat source unit according to claim 2, wherein the controller switches to the OFF-mode when the air temperature is lower than the predetermined temperature minus a differential temperature.

5. The heat source unit according to claim 4, wherein the differential temperature is input or selected from a plurality of given differential temperatures.

6. The heat source unit according to claim 1, wherein the first temperature sensor is disposed closer to a top of the external housing than to a bottom of the external housing.

7. The heat source unit according to claim 1, wherein the first temperature sensor is not in contact with the external housing.

8. The heat source unit according to claim 1, wherein the first temperature sensor is disposed in an area where the air temperature is not influenced by an air flowing out of the cooling heat exchanger.

9. The heat source unit according to claim 1, wherein the valve is a solenoid valve.

10. The heat source unit according to claim 1, further comprising a capillary disposed on the bypass line upstream of the cooling heat exchanger.

11. An air conditioner comprising: a refrigerant circuit; and a heat source unit that comprises: an external housing that accommodates: a compressor connected to the refrigerant circuit; a heat source heat exchanger that is connected to the refrigerant circuit and that exchanges heat between a refrigerant circulating in the refrigerant circuit and a heat source; and an electric box that: includes a top and a plurality of side walls; accommodates electrical components; and further includes an air passage comprising an air inlet and an air outlet, wherein an air flow is induced through the air passage from the air inlet to the air outlet for cooling at least some of the electrical components; a cooling heat exchanger disposed in the external housing and that is connected to the refrigerant circuit, wherein the air flow flows through the cooling heat exchanger, and the cooling heat exchanger exchanges heat between the refrigerant and the air flow, and is connected to a bypass line disposed between a liquid refrigerant line and a gas suction line; a valve disposed on the bypass line upstream of the cooling heat exchanger; a controller that controls the valve; a first temperature sensor disposed within the external housing and out of the electric box and that measures air temperature at a location where the first temperature sensor is disposed; a second temperature sensor disposed at an exit line between an exit of the cooling heat exchanger and a connection of the bypass line to the gas suction line, wherein the controller: switches the valve between an OFF-mode in which the valve is closed and an ON-mode in which the valve is opened based on the air temperature measured, determines a superheat degree of the refrigerant in the exit line based on a temperature detected by the second temperature sensor, switches between the ON-mode and the OFF-mode of the valve based on the superheat degree, and switches to the OFF-mode of the valve when the superheat degree falls below a predetermined value for a predetermined period of time, wherein the heat source unit is connected to at least one indoor unit that comprises an indoor heat exchanger that forms the refrigerant circuit.

12. The air conditioner according to claim 11, wherein the heat source unit is installed in an installation space.

13. The air conditioner according to claim 12, further comprising: a second temperature sensor disposed in the installation space, wherein the controller switches to an ON-mode in which the valve is opened when the air temperature is higher than a temperature measured by the second temperature sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an example of an air conditioner installed in an office building.

(2) FIG. 2 shows a schematic circuit diagram of a simplified air conditioner.

(3) FIG. 3 shows a schematic side view of a heat source unit with the side walls and the top of the external housing being removed.

(4) FIG. 4 shows an overall perspective view of a heat source unit.

(5) FIG. 5 shows a perspective view of the heat source unit of FIG. 4 with a maintenance plate of the external housing being removed.

(6) FIG. 6 shows a side view of the heat source unit of FIG. 4 with the side walls and the top of the external housing being removed.

(7) FIG. 7 shows a perspective view of the heat source unit of FIG. 4 with the side walls and the top of the external housing being removed.

(8) FIG. 8 shows a top view of the heat source unit of FIG. 4 with the side walls and the top of the external housing being removed.

(9) FIG. 9 shows a perspective view of the heat source unit of FIG. 4 with the side walls and the top of the external housing and the electric box being removed.

(10) FIG. 10 shows a graph showing a control mechanism according to an example.

DETAILED DESCRIPTION

(11) In the following description and the drawings, the same reference numerals have been used for the same elements and repetition of the description of these elements in the different embodiments is omitted.

(12) FIG. 1 shows an example of an air conditioner 1 installed in an office building. The office building has a plurality of rooms 105 to be conditioned such as conference rooms, a reception area and working places of the employees.

(13) The air conditioner 1 comprises a plurality of indoor units 100 to 102. The indoor units are disposed in the rooms 105 and may have different configurations, such as wall-mounted 102, ceiling mounted 101 or duct-type indoor units 100.

(14) The air conditioner further comprises a plurality of heat source units 2. The heat source units 2 are installed in an installation room 29 of the office building. Other equipment such as servers (not shown) may be installed in the installation room 29 as well. In the present example, the heat source units 2 use water as heat source. In the particular example, a water circuit 104 is provided which is connected to a boiler, dry-cooler, cooling tower, ground loop or the like. The water circuit 104 may as well have a heat pump circuit including a refrigerant circuit. An outdoor unit comprising the heat source heat exchanger of this heat pump circuit may be disposed on the roof of the office building and use air as the heat source. Yet, the concept of the heat source unit of the present disclosure is also applicable to other heat sources such as air or ground.

(15) In operation, one or more of the indoor units 100 to 102 may be operated to cool the respective rooms 105 whereas others are operated to heat the respective rooms.

(16) A simplified schematic diagram of the air conditioner is shown in FIG. 2. The air conditioner 1 in FIG. 2 is mainly constituted by an indoor unit 100 and the heat source unit 2. Yet, the air conditioner 1 in FIG. 2 may also have a plurality of indoor units 100. The indoor units may have any configuration such as those described with respect to FIG. 1 above.

(17) Further, FIG. 2 shows the refrigerant circuit constituting a heat pump. The refrigerant circuit comprises a compressor 3, a 4-way valve 4 for switching between cooling and heating operation, a heat source heat exchanger 5, an expansion valve 6, and optional additional expansion valve 7 and an indoor heat exchanger 103. The heat source heat exchanger 5 is additionally connected to the water circuit 104 as the heat source. When the compressor 3 is operated, a refrigerant is circulated in the refrigerant circuit.

(18) In cooling operation, high-pressure refrigerant is discharged from the compressor 3, flows through the 4-way valve 4 to the heat source heat exchanger 5 functioning as a condenser whereby the refrigerant temperature is decreased and gaseous refrigerant condensed. Thus, heat is transferred from the refrigerant to the water in the water circuit 104. Subsequently, the refrigerant passes the expansion valve 6 and the optional expansion valve 7, wherein the refrigerant is expanded before being introduced into the indoor heat exchanger 103 functioning as an evaporator. In the indoor heat exchanger 103, the refrigerant is evaporated and heat is extracted from the air in the room 105 to be conditioned, whereby the air is cooled and reintroduced into the room 105. At the same time, the temperature of the refrigerant is increased. Subsequently, the refrigerant passes the 4-way valve 4 and is introduced into the compressor 3 as low-pressure gaseous refrigerant at the suction side of the compressor 3. In view of the aforesaid, the line connecting the heat source heat exchanger 5 and the indoor heat exchanger 103 is considered a liquid refrigerant line 25. The line connecting the 4-way valve 4 and the suction side of the compressor 3 is considered a gas suction line 26.

(19) In heating operation, high-pressure refrigerant is discharged from the compressor 3, flows through the 4-way valve 4 to the indoor heat exchanger 103 (dotted line of the 4-way valve 4) functioning as the condenser, whereby the refrigerant temperature is decreased and gaseous refrigerant condensed. Thus, heat is transferred from the refrigerant to the air in the room 105 whereby the room is heated. Subsequently, the refrigerant passes the optional expansion valve 7 and the expansion valve 6, wherein the refrigerant is expanded before being introduced into the heat source heat exchanger 5 functioning as an evaporator via the liquid refrigerant line 25. In the heat source heat exchanger 5, the refrigerant is evaporated and heat is extracted from water in the water circuit 104. At the same time, the temperature of the refrigerant is increased. Subsequently, the refrigerant passes the 4-way valve 4 (dotted line of the 4-way valve 4) and is introduced into the compressor 3 as low-pressure gaseous refrigerant at the suction side of the compressor 3 via the gas suction line 26.

(20) The refrigerant circuit shown in FIG. 2 further comprises a bypass line 24 branched from the liquid refrigerant line 25 and connected to the gas suction line 26. In the particular example, the bypass line 24 is connected to the liquid refrigerant line 25 between the expansion valve 6 and the indoor heat exchanger 103. If the optional expansion valve 7 is provided, the bypass line 24 is connected between the expansion valve 6 and the optional expansion valve 7.

(21) The bypass line 24 comprises a valve 20 which may assume an open and a closed position (ON/OFF). The valve 20 may be a solenoid valve. Furthermore, the bypass line 24 comprises a capillary 21. In the particular example, the capillary 21 is disposed downstream of the valve 20 in the direction of the flow of refrigerant during cooling operation. Yet, the valve 20 may as well be disposed downstream of the capillary 21.

(22) Furthermore, a cooling heat exchanger 22 (described in more detail below) is connected to the bypass line 24 downstream of the capillary 21 and the valve 20 in the direction of flow of refrigerant during cooling operation. The function of this cooling heat exchanger 22, the valve 20 and the capillary 21 will be described further below.

(23) In one example, the components contained in the dotted rectangle indicating the heat source unit 2 in FIG. 2 are accommodated in an external housing 10 (see FIG. 4) of the heat source unit 2.

(24) As schematically indicated in FIG. 3 and shown in more detail in FIGS. 4 to 9, the external housing 10 has side walls 15 and a top 13 both shown in a dotted line. Furthermore, the external housing 10 has a bottom 14. Thus, the external housing 10 defines an interior 12 of the external housing 10 and an exterior 11 of the external housing 10 which in one example may be the installation room 29 as an example of an installation environment or installation space (see FIG. 1). In the present example, the bottom 14 has a drain pan 16 for collecting any condensation water accumulated in the external housing 10. The bottom 14 supports the remaining components of the heat source unit 2 to be explained in the following. According to one example, none of the components contained in the external housing 10 is fixed to the side walls 15 or the top 13, but all components are directly or indirectly, via the support structures, fixed to the bottom 14.

(25) As an example, the compressor 3, and a liquid receiver 8 commonly used in refrigerant circuits of air conditioners are shown as a components accommodated in the external housing 10. Further components are an oil separator 9 and an accumulator 108 (see FIG. 7). In this context, the compressor 3, the liquid receiver 8 and the oil separator 9 are considered as hot refrigerant components, because at least a proportion of the refrigerant passing through these components is gaseous and hot. The accumulator 108 in contrast is considered as a cold refrigerant component as only low pressure refrigerant passes through the accumulator 108.

(26) The external housing 10 may have vents 17 to allow ventilation of the interior 12 in case the later described zero heat dissipation control is not active.

(27) Furthermore, the heat source unit 2 comprises an electric box 30. The electric box 30 has the shape of a parallelepiped casing, but other shapes are conceivable as well. In the example, the electric box 30 has a top 31, the side walls (in the present example four side walls, namely a back 32, a front 33 and two opposite sides 34) and a bottom 35. In other embodiments, the bottom may be open. The electric box 30 has a height between the bottom end 35 and the top 31, a depth between the back 32 and the front 33 and a width between the two opposite sides 34. In one or more embodiments, the electric box 30 is longitudinal having a height larger (at least twice as large) than the depth and the width.

(28) The electric box 30 accommodates a plurality of electrical components 36 configured to control the air conditioner and particularly its components such as the compressor 3, the expansion valves 6 and 7 or the valve 20. The electrical components 36 are schematically shown in FIG. 3 only.

(29) The electric box 30 further defines an air passage 37 having an air inlet 38 and an air outlet 39. In one or more embodiments, the air inlet 38 is disposed closer to the bottom 35 or the bottom end of the electric box 30 than the air outlet 39. Even more particular, the air outlet 39 is located adjacent to the top 31 of the electric box 30. Due to the longitudinal configuration of the electric box 30 and it is orientation with respect to the longitudinal extension along a vertical direction, the air outlet 39 is located adjacent to a top 13 of the external housing 10 (closer to the top 13 than to the bottom 14). In addition, both the air inlet 38 and the air outlet 39 open into the interior 12 of the external housing 10.

(30) The electrical components 36, which require cooling, are either directly disposed in the air passage 37 as shown in FIG. 3 and/or a heat sink is provided which is heat conductively connected to electrical components to be cooled and the heat sink is directly disposed in the air passage 37.

(31) Furthermore, one or more embodiments show a fan 40 to induce an air flow 41 (arrows in FIG. 3) from the air inlet 38 to the air outlet 39 through the air passage 37. Accordingly, the air passes the electrical components 36 for cooling, wherein heat is transferred from the electrical components either directly or via the mentioned heat sink to the air flowing through the air passage 37. Certainly, also more than one fan 40 may be provided.

(32) In one or more embodiments, the fan 40 is arranged at the air outlet 39 of the air passage so that air from the interior 12 of the external housing 10 is sucked into the air inlet 38 passes through the air passage 37 and is expelled to the interior 12 of the external housing adjacent to the top 13 of the external housing 10. Accordingly, natural convection is assisted in that relatively cool air is expelled at the top and will naturally flow down towards the bottom 14.

(33) Furthermore and as shown in FIGS. 3, and 6 to 9, the cooling heat exchanger 22 is arranged downstream of the electrical components 36 as seen in the direction of the air flow 41. In the particular example, the cooling heat exchanger 22 is also disposed at the air outlet 39 of the air passage 37 and even downstream of the fan 40 in the direction of the air flow 41. In one example, the cooling heat exchanger 22 is attached to the air outlet 39 via a duct 23. The duct 23 forms an air passage between the air outlet 39 of the air passage 37 and an air inlet 27 of the cooling heat exchanger 22. The duct 23 can be used to change the direction of the air flow 41 and/or to mount a commonly known parallelepiped heat exchanger has the cooling heat exchanger 22 in an angled fashion as will be described later.

(34) As may be best seen in FIG. 7, the cooling heat exchanger 22 has a plurality of tubes 43 curved at end portions of the cooling heat exchanger 22 and passing a plurality of fins 42 schematically indicated in FIG. 7. The fins 42 are longitudinal, plate shaped and extend with their longitudinal extension along a vertical direction, i.e. between the bottom 14 and the top 13. It is to be understood, that extending along a vertical direction is as long realized as a longitudinal centerline of the fins 42 in a side view as in FIG. 3 does not intersect a vertical line at an angle of more than 45°. The fins 42 are flat and have a longitudinal extension (lengths) and widths much larger than the height, whereby a main surface of the fins 42 is defined by the length and the width.

(35) In the particular example, the cooling heat exchanger 22, and particularly the longitudinal direction of the fins 42, is angled by an angle α (see FIG. 3) relative to the vertical direction. Accordingly, an air outlet 28 of the cooling heat exchanger is oriented such that the air flow 41 is directed toward hot refrigerant components, in the present example the compressor 3, the liquid receiver 8 as well as an oil separator 9 (see FIG. 8). The angle α may be in a range between 0° and 25°. As a result, the air cooled by the cooling heat exchanger 22 and expelled from the air outlet 28 of the cooling heat exchanger 22 is also used to cool one or more of the hot refrigerant components. Consequently, the amount of heat dissipated by the heat source unit 2 as such can be reduced.

(36) Moreover, the cooling heat exchanger 22 has a bottom end portion 44 such as a bottom plate. In one or more embodiments, the bottom end portion 44 is downwardly inclined from the air inlet 27 of the cooling heat exchanger 22 towards the air outlet 28 of the cooling heat exchanger 22. In other words, the bottom end portion 44 slopes downward towards a bottom 14 of the external housing 10.

(37) As indicated in the introductory portion, there is a risk that condensation water forms on the cooling heat exchanger 22 because of the humidity in the air in the interior 12 of the external housing 10 and the temperature difference. Yet, the particular example provides several means for guiding any condensation water away from the air outlet 39 of the air passage 37 so as to prevent any water from coming into contact with the electrical components 36 or the heat sink in the air passage 37.

(38) On the one hand and as mentioned above, the fins 42 are oriented with their longitudinal direction along a vertical direction. Accordingly, any condensation water formed on the main surfaces of the fins 42 flows down along the fins 42 and, hence, in a vertical direction due to gravity. On the other hand, the bottom end portion 44 of the cooling heat exchanger 22 is downwardly inclined. Accordingly, any condensation water which has flown down the fins 42 and reaches the bottom end portion 44 is guided by the bottom end portion 44 to the air outlet 28 of the cooling heat exchanger 22. At a front edge of the air outlet 28 of the cooling heat exchanger 22, the condensation water may drop down into the drain pan 16 in the bottom 14 of the external housing 10. Thus, any condensation water is securely guided away from the air outlet 39 of the air passage 37.

(39) In addition and as previously mentioned, the cooling heat exchanger 22 is arranged at the air outlet 39 of the air passage 37 and consequently downstream of the electrical components 36 or the heat sink disposed in the air passage 37 in the direction of the air flow 41. Accordingly, the air flow 41 “blows” any condensation water formed on the cooling heat exchanger 22 in a direction away from the air outlet 39 and the electrical components 36. This configuration also assists preventing condensation water from coming into contact with sensible parts of the electric box 30.

(40) Even further, the fan 40 is disposed between the cooling heat exchanger 22 and to the electrical components 36 in the air passage 37. Accordingly, the fan 40 can be considered as a partition separating the cooling heat exchanger 22 from the air passage 37. Hence, the fan 40 is an additional barrier for condensation water and prevents the condensation water from entering the air passage 37.

(41) The electric box 30 is, in one or more embodiments, supported so as to be rotatable about an axis of rotation 46. The support structure 45 is shown in more detail in FIGS. 6 to 9. Thus, the electric box 30 is hinged to the support structure 45 so as to be movable between a use position shown in FIG. 3 and a maintenance position in which the electric box 30 is tilted about the axis of rotation 46 in a counterclockwise direction shown by the arrow in FIGS. 3 and 6. The axis of rotation 46 is located at a first end of the electric box close to the bottom 35, i.e. opposite to the top 31. Furthermore, the electric box 30 is at the top 31 releasably fixed to the support structure to retain the electric box 30 in the use position by bolts 57 (see FIG. 5).

(42) In the embodiments shown in FIGS. 6 to 9, the support structure 45 (best visible from FIG. 9) is formed by a frame 47. The frame 47 is fixed to the bottom 14 of the external housing 10. The frame 47 has two upright columns 48. The columns 48 are mounted to the bottom 14 of the external housing 10.

(43) Each of the columns 48 has at its bottom end close to the bottom 14 of the external housing 10 a slot 49. A boss 50 is provided on either side 34 of the electric box 30 and engaged with one of the slots 49. Different to the schematic view in FIG. 3, the detailed representation of the slot 49 in FIGS. 6 and 7 shows an inserting portion 51 used to insert the boss 50 into the slot 49 or to remove the boss 50 from the slot 49 and, hence, to completely remove the electric box 30 from the heat source unit 2. The inserting portion 51 has an opening 52 at one end for introducing the boss 50. Furthermore, an engagement portion 53 is formed at the opposite end of the inserting portion 51. The engagement portion has a lower section 54 supporting the boss 50 in the use position in an upward direction and an upper section 55 supporting the boss 50 in the maintenance position in a downward direction. The axis of rotation 46 is formed by the bosses 50. It is also clear from the side view of FIG. 6, that the center of gravity 56 of the electric box 30 is arranged so that the electric box 30 tends to rotate about the axis of rotation 46 in a clockwise direction that is towards the interior 12 of the external housing 10.

(44) As previously mentioned, the electric box 30 may be releasably fixed to the frame 47 by bolts 57 (see FIG. 5). When releasing the bolts 57 at the upper end near the top 31 of the electric box 30 from the frame 47, the electric box may be rotated about the axis of rotation 46 or the bosses 50, respectively, in a counterclockwise direction as will be explained in more detail below. For rotating the electric box 30, it is conceivable to provide a handle 64 (see FIG. 5) in or at an outer surface of the electric box 30.

(45) The cooling heat exchanger 22 is in the present example together with the duct 23 fixed to the frame 47 by bolts. As may be best seen from FIG. 9, the air outlet 39 or more particularly an opening 59 of the frame 47 facing the air outlet 39 of the air passage 37 is surrounded by an elastic sealing 60. The elastic sealing 60 is as well fixed to the frame 47. The sealing, particularly the contact surface of the sealing facing the electric box 30 defines a plane 61. The center of gravity 56 is in a side view (FIG. 6) disposed between the plane 61 and the axis of rotation 46 (formed by the boss 50). Thus, the electric box 30 tends to rotate against the contact surface of the sealing 60 by gravity ensuring a proper contact with the sealing at the air outlet 39 between the outlet 39 and the cooling heat exchanger 22 and its optional duct 23. Certainly, other or further possibilities to seal between the outlet 39 and the cooling heat exchanger 22 and its optional duct 23 are conceivable. For example, the sealing could also be established by correct dimensioning and adding sufficient fixation points between the mating surfaces. Moreover, a separate clamping element may be used to press the mating surfaces together.

(46) The electrical components 36 in the electric box 30 need to be connected to some of the components of the refrigerant circuit contained in the external housing 10. For this purpose, the electric box 30 has either an open bottom or an opening is provided in the bottom 35. A first electric wire 62 connected to a first electric component in the electric box 30 leaves the electric box through the bottom end of the electric box 30 and is connected to the first electric component such as the solenoid valve 20 (see FIG. 2 and FIG. 8). For this purpose, the electric wire 62 schematically indicated in FIG. 3 is guided from the bottom 35 to the bottom 14 of the external housing 10, along the bottom 14 and from the bottom 14 to the first electric component (in the example the valve 20).

(47) Under some circumstances and for EMC (electromagnetic compatibility) reasons, some electric wires need to be separated from other electric wires. Accordingly, it is conceivable that a second electric wire 63 leaves the electric box 30 through an opening 70 (see FIG. 7) between the bottom 35 and the top 31 of the electric box 30. Also, the second electric wire 63 is guided to the bottom 14 of the external housing 10 and from the bottom to the component such as the compressor 3. Neither the first electric wire 62 nor the second electric wire 63 is fixed to the bottom 14 of the external housing 10 in the example.

(48) In the case that maintenance of electric components 36 or refrigerant components or the fan 40 of the electric box 30 is required, one has to remove a maintenance wall 106 of the external housing 10 (see FIG. 4). For this purpose, the bolts 107 are removed and subsequently the maintenance wall 106 can be removed as shown in FIG. 5. Once the maintenance wall 106 has been removed, one can loosen the bolts 57 at the top end of the electric box 30 (FIG. 5) and pivot the electric box 30 about the axis of rotation 46, formed by the bosses 50, out through the opening created by removing the maintenance wall 106. During this process, the boss 50 moves from the lower section 54 of the engagement portion 53 of the slot 49 into the upper section 55 of the engagement portion 53 of the slot 49. Accordingly, the electric box 30 is reliably held in the slot 49 and can easily be pivoted.

(49) As will be apparent from the above description, the electric box 30 and the cooling heat exchanger 22 are independently fixed to the support structure 45 (the frame 47). There is no attachment of the electric box 30 to the cooling heat exchanger 22. Accordingly, moving the electric box 30 into the maintenance position (not shown) does not affect the cooling heat exchanger 22 and its refrigerant piping 24. The cooling heat exchanger 22, the duct 23 (if present) and the sealing 60 remain mounted in their position on the frame 47 and are not moved together with the electric box 30. In this context, the fan 40 may as well be fixed to the electric box 30 and may be pivoted into the maintenance position together with the electric box 30 to enable easy maintenance or substitution of a damaged fan 40.

(50) When the electric box 30 is moved into the maintenance position, the first electric wire 62 guided through the bottom 35 of the electric box 30 moves towards the inner side of the external housing 10 and, therefore, in a direction toward the electrical component 20 to which it is connected. Accordingly, no strain is applied to the first electric wire 62 by moving the electric box 30 into the maintenance position.

(51) The second electric wire 63 leaving the electric box through the opening 70 is first guided to the bottom 13 of the external housing 10. Thus, there is a certain free length of the second electric wire 63 between the opening 70 and the connection to the compressor 3. Thus, also in this case strain on the second electric wire 63 can be avoided when moving the electric box 30 into the maintenance position.

(52) The above configuration enables easy access to the electric box and does not require any disassembly/assembly work on the cooling heat exchanger 22 and its refrigerant piping 24. For this reason, damages to the cooling heat exchanger 22 and its refrigerant piping 24 can be prevented.

(53) After the maintenance, the electric box 30 is pivoted about the axis of rotation 46 (bosses 50) in an opposite direction (clockwise in FIGS. 3 and 6) into the use position shown in the drawings. During this process, the boss 50 again moves back to the lower section 54 of the engagement portion 53 of the slot 49 so that the electric box 30 is securely supported in a vertical direction. Because the center of gravity 56 is closer to a plane 61 formed by the contact surface of the sealing 60 than to the axis of rotation 46 (bosses 50) in a side view, the weight of the electric box 30 ensures that the electric box 30 is securely pressed against the contact surface of the sealing 60 and does even without the bolts 57 not “drop” out of the maintenance opening. Subsequently, the bolts 57 are reinserted and the maintenance wall 106 is reinstalled.

(54) Further, a controller 65 is provided which is schematically shown in FIG. 2. The controller 65 has the purpose of controlling the air conditioner 1 and particularly the refrigerant circuit. The controller 65 may be accommodated in the electric box 30.

(55) The controller 65 may be configured to control the air conditioner 1 on the basis of parameters obtained from different sensors.

(56) For example, a first temperature sensor 66 is disposed in the interior 12 of the external housing 10. Thus, the first temperature sensor 66 detects the temperature in the interior 12 of the external housing 10. In this context, the position of the first temperature sensor 66 is determined relative to the position of the other components in the external casing at a position in which a relatively stable and representative temperature can be measured. Thus, this position has to be determined by experiments.

(57) A second temperature sensor 67 may be arranged in the installation room 29 in which the heat source unit 2 is installed. The second temperature sensor 67, hence, measures a temperature in the installation room 29 in other words the temperature of the environment (exterior) of the external housing 10.

(58) Another parameter used by the controller 65 is a thermistor 68 (third temperature sensor) at an exit line 69 between the cooling heat exchanger 22 and a suction side of the compressor 3 (see FIG. 2). In one or more embodiments, it is conceivable that an accumulator 108 is disposed in the line between the cooling heat exchanger 22 and the inlet of the compressor 3 (suction side). In general, the exit line 69 is to be understood as that line connecting the cooling heat exchanger 22 to the gas suction line 26, i.e. between an exit of the cooling heat exchanger 22 and the connection of the bypass line 24 to the gas suction line 26. The thermistor 68 measures the temperature of the refrigerant in the exit line 69. Further, a pressure sensor 71 is provided and configured to measure the pressure of the refrigerant in the gas suction line 26.

(59) The operation of the air conditioner with respect to the cooling heat exchanger 22 is described in more detail below. This operation may also be referred to as the zero heat dissipation control (ZED=zero energy dissipation).

(60) In principle, one can choose between three settings explained in more detail and shown in the table below.

(61) TABLE-US-00001 Setting 0 1 2 Zero heat OFF ON ON dissipation priority on priority on control cooling zero heat capacity dissipation

(62) In setting “0”, the valve 20 is completely closed and no refrigerant flows through the cooling heat exchanger 22. In this setting, the electric components 36 may still be cooled by operating the fan but the heat is dissipated to the interior 12 of the external casing 10, and hence the external casing 10 and the heat source unit 2 dissipate heat to the installation room 29. The zero heat dissipation control is switched OFF.

(63) If setting “1” is selected, zero heat dissipation control is ON. Yet, in this setting, the cooling capacity of the air conditioner has priority over the zero heat dissipation control. In particular, if a temperature measured in a room 105 to be conditioned exceeds a set temperature of the air conditioner in that room 105 by a certain value, and the air conditioner can only satisfy this additional cooling demand if the zero heat dissipation control is deactivated, the valve 20 will be closed. To put it differently, the valve 20 is closed, when a required cooling capacity of the air conditioner exceeds a predetermined threshold. For example, a heat source heat exchanger 5 can transfer a certain amount of heat (further referred to as 100% heat load) to (in this example) water (water circuit 104) at certain operating conditions. During operation with deactivated ZED control, the heat source unit 4 can remove heat from the room (105) in correspondence with 100% heat load (cooling operation). Assuming that the heat loss from the electronic components and hot refrigerant components corresponds to 4% of the total heat load, only 96% of heat load (cooling capacity) can be used to cool the room 105 during cooling operation. If the above setting is activated, the ZED control can be deactivated resulting in a 100% available capacity to cool the room 105. During heating operation of the room 105, the heat source heat exchanger 5 will subtract 100% of heat from the water in the water circuit 104 and deliver this heat, together with the 4% heat loss from the electric components 36, to the room 105. This results in a heating capacity of 104%, whereby the heating performance of the air conditioner 1 is increased.

(64) If setting “2” is selected, zero heat dissipation control is ON independent of the cooling capacity of the air conditioner. However, under a certain special control operation, such as start-up and oil return, zero heat dissipation control is still deactivated (the valve 20 is closed) in order to avoid damaging of the compressor 3 due to liquid refrigerant flowing back into the compressor 3. During start-up mode for example, the rotational speed of the compressor increases to nominal speed. At a low rotational speed, the circulated refrigerant amount is low. Yet, if the distance between the heat source unit 2 and the indoor unit 100 is large, the refrigerant in the liquid line connecting the heat source unit 2 and the indoor unit 100 has a relatively high inertia. In contrast, the bypass line 24 is relatively short and has a low inertia. As a consequence, a higher proportion of the refrigerant flows through the bypass line 24, whereas a reduced amount or even no refrigerant may flow to the indoor unit 100. This may result in lower comfort in the room 105 in which the indoor unit 100 is mounted. This may be prevented by closing the valve 20. During oil return operation, a high mass flow rate is generated to flush oil out of the refrigerant circuit components. If the valve 20 is open, the mass flow rate through the refrigerant circuit component was reduced resulting in a decreased oil return efficiency.

(65) In either case, the zero heat dissipation control may be performed on the basis of different parameters.

(66) According to a first possibility, the temperature of the interior 12 of the external casing 10 is measured by the first temperature sensor 66 and the controller 65 controls the valve 20 on the basis of the temperature measured by the first temperature sensor 66.

(67) In particular, the controller 65 compares the temperature measured by the first temperature sensor 66 with a predetermined temperature. In one or more embodiments, it is preferred that one either freely inputs the predetermined temperature or can select from different settings as shown in the table below to define the predetermined temperature.

(68) TABLE-US-00002 Setting 0 1 2 3 4 5 6 7 Predetermined 25 27 29 31 33 35 37 39 temperature [° C.]

(69) Further, one either freely inputs a differential temperature or again selects the differential temperature from different settings as shown in the table below to define the differential temperature.

(70) TABLE-US-00003 Setting 0 1 2 3 Differential 3 2 1 5 temperature [° C.]

(71) According to this control, the controller 65 compares the temperature measured by the first temperature sensor 66 with the predetermined temperature. If the temperature measured by the first temperature sensor 66 exceeds the predetermined temperature, the controller 65 is configured to activate the zero heat dissipation control and open the valve 20 (completely).

(72) Then again and as shown in FIG. 10, if the temperature measured by the first temperature sensor 66 falls below the predetermined temperature minus the selected differential temperature, the controller 65 is configured to deactivate the zero heat dissipation control and close the valve 20 (completely).

(73) For example, if the setting “3” is selected for the predetermined temperature, the predetermined temperature is 31° C. Further, if the setting “0” is selected for the differential temperature, the differential temperature is 3° C. If for example the temperature measured by the first temperature sensor 66 in the interior 12 of the external housing 10 exceeds 31° C., the valve 20 is opened by the controller 65. Accordingly, the refrigerant flows through the capillary 21, is expanded and then flows into the cooling heat exchanger 22. In the cooling heat exchanger, the refrigerant extracts heat from the air flow 41 by heat exchange, whereby the air flow 41 is cooled and cooled air is expelled into the interior 12 of the external housing 10. Thereby also the hot refrigerant components such as the compressor 3, the liquid receiver 8 and the oil separator 9 are cooled, because of the orientation of the air outlet 28 of the cooling heat exchanger 22 in an angled fashion. In particular, the cooled air flow 41 is directed in a direction of the hot refrigerant components which are accordingly cooled. In any case, air that is cooler than the air in the interior 12 of the external housing 10 is expelled from the cooling heat exchanger 22 into the interior 12. As a result, the temperature decreases in the external housing 10. Once the temperature measured by the first temperature sensor 66 falls below 28° C. (31° C.-3° C.), the controller 65 closes the valve 20 and no refrigerant flows through the cooling heat exchanger 22. This process is repeated as shown in FIG. 10.

(74) Alternatively or in addition to the above control, it is also conceivable to use a second temperature sensor 67 disposed in the installation room 29 and measuring the temperature in the installation room 29 to control the valve 20.

(75) In this context, it is conceivable that the zero heat dissipation control is activated (the valve 20 is opened) if the temperature detected by the first temperature sensor 66 is higher than the temperature measured by the second temperature sensor 67. For example, it may be that the controller 65 overrides the above control related to the first temperature sensor 66, if the temperature measured by the second temperature sensor 67 is lower than the temperature detected by the first temperature sensor 66 and closes the valve 20 despite the fact that the temperature measured by the first temperature sensor 66 is higher than the predetermined temperature.

(76) An even further possibility is that instead of using the first temperature sensor 66 to merely use the second temperature sensor 67 and control the valve 20 on the basis of a comparison between the temperature measured by the second temperature sensor 67 and a predetermined temperature. The predetermined temperature may be a no-room-impact-temperature. The predetermined temperature may be selected in the same manner as explained above with respect to the first temperature sensor 66.

(77) According to a first example, it may be sufficient to compare the predetermined temperature and the temperature measured by the second temperature sensor 67 and if the temperature of the second temperature sensor 67 exceeds the selected predetermined temperature, the valve 20 is opened to activate the zero heat dissipation control. Subsequently, if the temperature measured by the second temperature sensor 67 falls below the predetermined temperature minus the differential temperature, the valve 20 is again closed.

(78) According to a second example, it is as well conceivable to define a second differential temperature in the same manner as the first differential temperature. If the temperature measured by the second temperature sensor 67 is higher than the predetermined temperature (no-room-impact-temperature) and the delta between the temperature measured by the second temperature sensor 67 and the predetermined temperature is higher than the second differential temperature, the valve 20 is opened. In the same manner as described above and according to a first possibility, if the temperature measured by the second temperature sensor 67 falls below the predetermined temperature by the first differential temperature, the valve 20 is closed and the zero heat dissipation control is deactivated. Alternatively, the valve 20 may also be closed if the temperature measured by the second temperature sensor 67 falls below the predetermined temperature (no-room-impact-temperature) without the use of the first differential temperature.

(79) An even further control mechanism to activate/deactivate the zero heat dissipation control (open/close the valve 20) may be based on the thermistor 68 disposed at the exit line 69 and particularly the temperature of the refrigerant in the exit line 69 measured by the thermistor 68. Further, the controller 65 uses the pressure measured by the pressure sensor 71 disposed at the gas suction line 26. In particular, the controller 65 concludes on the two-phase temperature (the temperature at which a phase change from liquid to gas takes place) on the basis of the pressure measured by the pressure sensor is 71. Subsequently, the controller 65 compares this two-phase temperature and the temperature measured by the thermistor 68. If the temperature measured by the thermistor 68 is higher than the two-phase temperature, it is concluded that superheated gaseous refrigerant leaves the cooling heat exchanger 22. The output of the thermistor 68 is, hence, used by the controller 65 to conclude or calculate on the basis of a pressure in the gas suction line 26 and the temperature at an outlet of the cooling heat exchanger 22 (cooling heat exchanger gas outlet) on a superheat degree. Subsequently, and depending on the superheat degree the valve 20 is opened or closed. This control is particularly a safety measure to prevent liquid refrigerant from remaining in the exit line 26 and/or being pumped into the accumulator 108 (if present) or the compressor 3. In particular, the controller 65 is configured to switch to the OFF-mode of the valve 20, when the calculated superheat degree falls below a predetermined value for a predetermined period of time. During operation, the pressure difference between the liquid line 25 and the gas suction line 26 will depend on the operational conditions of the heat source unit 2. If there is a pressure drop in the bypass line 24, a refrigerant flow may be induced from the gas suction line 26 into the bypass line 24. Depending on the air temperature in the external housing 10, the refrigerant flowing through the cooling heat exchanger 22 and the thermal capacity of the air may be out of balance resulting in a fully evaporated refrigerant with a possible high superheat or a not fully evaporated refrigerant which contains liquid refrigerant. Those extreme situations may be avoided by opening/closing the valve 20 on the basis of the superheat degree obtained via the thermistor.

REFERENCE SIGNS LIST

(80) Air conditioner 1 Heat source unit 2 Compressor 3 4-Way valve 4 Heat source heat exchanger 5 Expansion valve 6 Optional expansion valve 7 Liquid receiver 8 Oil separator 9 External housing 10 Exterior of the external housing 11 Interior of the external housing 12 Top of the external housing 13 Bottom of the external housing 14 Side walls of the external housing 15 Drain Pan 16 Vents 17 Valve 20 Capillary 21 Cooling heat exchanger 22 Duct 23 Bypass line 24 Liquid refrigerant line 25 Gas suction line 26 Air inlet of cooling heat exchanger 27 Air outlet of the cooling heat exchanger 28 Installation room 29 Electric box 30 Top of the electric box 31 Back of the electric box 32 Front of the electric box 33 Sides of the electric box 34 Bottom of the electric box 35 Electrical components 36 Air passage 37 Air inlet of the air passage 38 Air outlet of the air passage 39 Fan 40 Air flow 41 Fins 42 Tubes 43 Bottom end portion of the cooling heat exchanger 44 Support structure 45 Axis of rotation 46 Frame 47 Column 48 Slot 49 Boss 50 Insertion portion 51 Opening of the insertion portion 52 Engagement portion 53 Lower section 54 Upper section 55 Center of gravity 56 Bolts 57 Opening 59 Sealing 60 Plane of the contact surface of the sealing 61 First electric wire 62 Second electric wire 63 Handle 64 Controller 65 First temperature sensor 66 Second temperature sensor 67 Thermistor 68 Exit line 69 Opening 70 Pressure sensor 71 Indoor unit 100 to 102 Indoor heat exchanger 103 Water circuit 104 Rooms 105 Maintenance wall 106 Bolts 107 Accumulator 108 Outdoor unit 109

(81) Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.