Technical Field
[0001] Embodiments of the present invention described herein relate generally to a heat
source system.
Background Art
[0002] A technique in which an outdoor unit includes a heat exchanger used to carry out
heat exchange between a refrigerant and outdoor air, compressor used to compress the
refrigerant, heater used to heat the compressor, outdoor air temperature detector
used to detect the outdoor air temperature, and control device and, when the operation
of the compressor is stopped, the control device makes the heating control of the
compressor using the heater switchable in a multi-step manner on the basis of the
outdoor air temperature detected by the outdoor air temperature detector to thereby
prevent a refrigerant stagnation phenomenon from occurring is known. Here, the term
stagnation phenomenon implies a phenomenon in which after the operation of the compressor
is stopped, the refrigerant collects inside the casing of the compressor the temperature
of which has lowered to condense and then merges into the refrigeration machine oil
inside the casing.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0004] Incidentally, there are also cases where the outdoor air temperature detected by
the outdoor air temperature detector and actual temperature of the compressor are
different from each other. In order to cope with such a case, it is conceivable that
when the heating control of the compressor is switched over, control may be carried
out in such a manner as to cope with the severest environmental condition. Although
when the heating control is executed in such a manner, it becomes possible to cope
with even the case where the severest environmental condition is imposed, on the other
hand, in the case where the severest environmental condition is not imposed, the compressor
is subjected to excessive heating control. In such circumstances, useless electric
power is wasted on the heating control of the compressor.
[0005] The purpose of the present invention described herein aim to acquire a heat source
system capable of appropriately preventing a refrigerant stagnation phenomenon from
occurring, and further reducing the power consumption of the compressor heating control.
Solution to Problem
[0006] According to one embodiments, a heat source system which executes air conditioning
by refrigerating cycles comprises an outdoor air temperature measuring unit which
measures an outdoor air temperature, heating units which heat compressors used for
the refrigerating cycles, memory units each of which stores a relationship between
a temperature difference between an outdoor air temperature measured by the outdoor
air temperature measuring unit and a refrigerant saturation temperature at the time
of saturation of a refrigerant and an intermittent operation period of each of the
heating units, and control units each of which calculates, at the time when each of
the compressors is in a stopped state, the temperature difference between the outdoor
air temperature measured by the outdoor air temperature measuring unit and the refrigerant
saturation temperature at the time of saturation of the refrigerant, determines an
energization ratio of the intermittent operation on the basis of this calculation
result and the relationship stored in each of the memory units, and executes heating
control of each of the heating units according to the determined energization ratio.
Brief Description of Drawings
[0007]
FIG. 1 is a perspective view showing an example of a heat source system according
to a first embodiment.
FIG. 2 is a view showing an example of the control configuration of the heat source
system according to the first embodiment.
FIG. 3 is a view showing an example of the configuration of a refrigerating cycle
according to the first embodiment.
FIG. 4 is a view showing an example of a relationship between a temperature difference
between the refrigerant saturation temperature and outdoor air temperature and intermittent
operation ratio according to the first embodiment.
FIG. 5 is a view showing an example of an intermittent operation ratio according to
the first embodiment.
FIG. 6 is flowchart showing an example of the processing of intermittent operation
control according to the first embodiment.
FIG. 7 is a view showing an example of the configuration of a first controller according
to a second embodiment.
FIG. 8 is a view showing an example of startup control of the compressor according
to the second embodiment.
FIG. 9 is a view for explaining the case where two startup patterns according to the
second embodiment are utilized.
FIG. 10 is a view showing an example of the configuration of a first controller according
to a third embodiment.
FIG. 11 is a view showing an example of startup control of the compressor according
to the third embodiment.
[0008] Mode for Carrying Out the Invention Embodiments of the present invention will be
described below with reference to the accompanying drawings.
(First Embodiment)
[0009] FIG. 1 is a perspective view showing an example of a heat source system 10 which
is an air-cooling type heat pump chilling device configured to produce cold water
or warm water.
[0010] In the heat source system 10, three air-cooling type heat pump chilling units 11,
12, and 13 are arranged adjacent to each other in the lateral direction. The heat
source system 10 is an example of a heat source system, and can be operated in the
cooling mode and heating mode. It should be noted that, although, in this embodiment,
the heat source system 10 is described about the case where the heat source system
10 includes the three air-cooling type heat pump chilling units 11, 12, and 13, the
heat source system 10 may also be configured in such a manner as to include two or
four or more air-cooling type heat pump chilling units. Further, the heat source system
10 is installed on a horizontal installation surface such as a roof terrace of a building.
[0011] A housing 2 of the air-cooling type heat pump chilling unit is formed into approximately
a box-like shape having a depth dimension greater than the width dimension. Here,
the air-cooling type heat pump chilling unit of this embodiment includes four refrigerating
cycle circuits each of which is formed by connecting in sequence a compressor, four-way
valve, air heat exchanger (outdoor heat exchanger), expanding device, and water heat
exchanger to each other by refrigerant piping. The refrigerating cycle circuit will
be described later with reference to FIG. 3. The housing 2 of this embodiment is constituted
of an upper structure 21 and lower structure 22. The upper structures 21 are configured
in such a manner that four circuits 11a to 11d, 12a to 12d, and 13a to 13d each of
which includes air heat exchangers and other constituent members for each refrigerating
cycle circuit are respectively arranged in the longitudinal direction of the air-cooling
type heat pump chilling units 11, 12, and 13.
[0012] Next, an example of the control configuration of the heat source system 10 will be
described below with reference to FIG. 2.
[0013] As shown in FIG. 2, control units 111, 112, and 113 are respectively provided in
such a manner as to correspond to the air-cooling type heat pump chilling units 11,
12, and 13. It should be noted that configurations common to and possessed by the
three control units 111, 112, and 113 are denoted by reference symbols identical to
each other and detailed descriptions of the configurations are omitted.
[0014] Each of the control units 111, 112, and 113 includes a first controller 120, first
refrigerant circuit RA, second refrigerant circuit RB, third refrigerant circuit RC,
and fourth refrigerant circuit RD. The control unit 112 further includes a second
controller 130 in addition to these configurations. It should be noted that each of
the first to fourth refrigerant circuits RA to RD includes elements necessary for
the refrigerating cycle such as a compressor, heat exchangers, and the like.
[0015] Further, the first controller 120 includes a memory 121. The memory 121 is a nonvolatile
memory medium such as a flash ROM. This memory 121 includes a first area 122 in which
information such as a relationship or the like between the refrigerant saturation
temperature at the time of saturation of the refrigerant and energization ratio of
the intermittent operation period corresponding to the temperature difference between
the refrigerant saturation temperature and outdoor air temperature is stored, the
relationship being used by the first controller 120 in executing the heating control
of the compressor. Here, the refrigerant saturation temperature is calculated by using
a conversion formula on the basis of, for example, a pressure measured by a pressure
sensor configured to detect the pressure inside the refrigerating cycle circuit.
[0016] As shown in FIG. 2, the first refrigerant circuit RA, second refrigerant circuit
RB, third refrigerant circuit RC, and fourth refrigerant circuit RD are controlled
according to an instruction from the first controller 120.
[0017] It should be noted that a relay unit or the like may be made to intervene between
the first controller 120 and each of the first to fourth refrigerant circuits RA,
RB, RC, and RD.
[0018] The second controller 130 is connected to the first controller 120 in the control
unit 112, and to the first controller 120 in each of the control units 111 and 113.
Furthermore, the second controller is connected to an operation panel 140. The second
controller 130 outputs an instruction to each of the three first controllers 120 on
the basis of a condition set by the operator through the operation panel 140 and state
or the like of a load (illustration omitted) connected to the heat source system 10
to thereby operate the heat source system 10 in the cooling mode and heating mode.
[0019] Furthermore, the second controller 130 is connected to an outdoor air temperature
measuring unit (outdoor air temperature measuring device) 150. The outdoor air temperature
measuring unit 150 is a device configured to measure the temperature of the air outside
the heat source system 10. The temperature measured by the outdoor air temperature
measuring unit 150 is sent to the second controller 130 and is further transmitted
from the second controller to each of the three first controllers 120. It should be
noted that the configuration may also be contrived in such a manner that the measured
outdoor air temperature is directly transmitted from the outdoor air temperature measuring
unit 150 to the three first controllers 120. Further, the outdoor air measuring unit
150 may also be provided in each of the air-cooling type heat pump chilling units
11, 12, and 13.
[0020] FIG. 3 is a view showing an example of the configuration of refrigerating cycles
of each of the air-cooling type heat pump chilling units 11, 12, and 13.
[0021] A refrigerant discharged from a compressor 21 flows into air heat exchangers 23a
and 23b through a four-way valve 22, the refrigerant passing through the air heat
exchangers 23a and 23b flows into a first refrigerant flow path of a water heat exchanger
30 through electronic expansion valves 24a and 24b. The refrigerant passing through
the first refrigerant flow path of the water heat exchanger 30 is sucked into the
compressor 21 through the four-way valve 22 and accumulator 25. This refrigerant flow
direction is the direction at the time of the cooling operation (coldwater producing
operation), the air heat exchangers 23a and 23b function as a condenser, and first
refrigerant flow path of the water heat exchanger 30 functions as an evaporator. At
the time of the heating operation (warm-water producing operation), the flow path
of the four-way valve 22 changes to reverse the flow of the refrigerant, the first
refrigerant flow path of the water heat exchanger 30 functions as a condenser, and
air heat exchangers 23a and 23b function as an evaporator.
[0022] The compressor 21, four-way valve 22, air heat exchangers 23a and 23b, electronic
expansion valves 24a and 24b, first refrigerant flow path of the water heat exchanger
30, and accumulator 25 constitute a first heat pump refrigerating cycle.
[0023] A refrigerant discharged from a compressor 41 flows into air heat exchangers 43a
and 43b through a four-way valve 42, the refrigerant passing through the air heat
exchangers 43a and 43b flows into a second refrigerant flow path of the water heat
exchanger 30 through electronic expansion valves 44a and 44b. The refrigerant passing
through the second refrigerant flow path of the water heat exchanger 30 is sucked
into the compressor 41 through the four-way valve 42 and accumulator 45. This refrigerant
flow direction is the direction at the time of the cooling operation (coldwater producing
operation), the air heat exchangers 43a and 43b function as a condenser, and second
refrigerant flow path of the water heat exchanger 30 functions as an evaporator. At
the time of the heating operation (warm-water producing operation), the flow path
of the four-way valve 42 changes to reverse the flow of the refrigerant, the second
refrigerant flow path of the water heat exchanger 30 functions as a condenser, and
air heat exchangers 43a and 43b function as an evaporator.
[0024] The compressor 41, four-way valve 42, air heat exchangers 43a and 43b, electronic
expansion valves 44a and 44b, second refrigerant flow path of the water heat exchanger
30, and accumulator 45 constitute a second heat pump refrigerating cycle.
[0025] A refrigerant discharged from a compressor 51 flows into air heat exchangers 53a
and 53b through a four-way valve 52, the refrigerant passing through the air heat
exchangers 53a and 53b flows into a first refrigerant flow path of a water heat exchanger
60 through electronic expansion valves 54a and 54b. The refrigerant passing through
the first refrigerant flow path of the water heat exchanger 60 is sucked into the
compressor 51 through the four-way valve 52 and accumulator 55. This refrigerant flow
direction is the direction at the time of the cooling operation (coldwater producing
operation), the air heat exchangers 53a and 53b function as a condenser, and first
refrigerant flow path of the water heat exchanger 60 functions as an evaporator. At
the time of the heating operation (warm-water producing operation), the flow path
of the four-way valve 52 changes to reverse the flow of the refrigerant, the first
refrigerant flow path of the water heat exchanger 60 functions as a condenser, and
air heat exchangers 53a and 53b function as an evaporator.
[0026] The compressor 51, four-way valve 52, air heat exchangers 53a and 53b, electronic
expansion valves 54a and 54b, first refrigerant flow path of the water heat exchanger
60, and accumulator 55 constitute a third heat pump refrigerating cycle.
[0027] A refrigerant discharged from a compressor 71 flows into air heat exchangers 73a
and 73b through a four-way valve 72, the refrigerant passing through the air heat
exchangers 73a and 73b flows into a second refrigerant flow path of the water heat
exchanger 60 through electronic expansion valves 74a and 74b. The refrigerant passing
through the second refrigerant flow path of the water heat exchanger 60 is sucked
into the compressor 71 through the four-way valve 72 and accumulator 75. This refrigerant
flow direction is the direction at the time of the cooling operation (coldwater producing
operation), the air heat exchangers 73a and 73b function as a condenser, and second
refrigerant flow path of the water heat exchanger 60 functions as an evaporator. At
the time of the heating operation (warm-water producing operation), the flow path
of the four-way valve 72 changes to reverse the flow of the refrigerant, the second
refrigerant flow path of the water heat exchanger 60 functions as a condenser, and
air heat exchangers 73a and 73b function as an evaporator.
[0028] The compressor 71, four-way valve 72, air heat exchangers 73a and 73b, electronic
expansion valves 74a and 74b, second refrigerant flow path of the water heat exchanger
60, and accumulator 75 constitute a fourth heat pump refrigerating cycle.
[0029] The water inside the water piping 2b is guided to the water piping 2a through a water
flow path of the water heat exchanger 60 and water flow path of the water heat exchanger
30.
[0030] A pump 80 is arranged in the water piping between the water piping 2b and water flow
path of the water heat exchanger 60. The pump 80 includes a motor operated by an AC
voltage supplied from an inverter 81, and the pump head varies according to the rotational
speed of the motor. The inverter 81 rectifies a voltage of the commercial AC power,
converts the rectified DC voltage into an AC voltage of a predetermined frequency
by switching, and supplies the converted AC voltage as the drive power of the motor
of the pump 80. By changing the frequency (operation frequency) F of the output voltage
of the inverter 81, the rotational speed of the motor of the pump 80 is changed.
[0031] A differential pressure sensor 90 is arranged between the water piping of the water
heat exchanger 60 on the water inflow side and water piping of the water heat exchanger
30 on the water outflow side. The differential pressure sensor 90 detects a difference
(water pressure difference between the water heat exchangers 60 and 30) between the
pressure of the water flowing into the water heat exchanger 60 and pressure of the
water flowing out of the water heat exchanger 30. On the basis of the detected differential
pressure of the differential pressure sensor 90, it is possible to detect the quantity
of the water flowing through each of the water heat exchangers 60 and 30, i.e., the
quantity of the water flowing through the heat source equipment.
[0032] Further, a heater wire (hereinafter referred to as a "case heater") 21a, 41a, 51a,
and 71a which is a heating unit is wound around the outside of each compressor 21,
41, 51, and 71. Each of the case heaters 21a, 41a, 51a, and 71a is provided for the
purpose of heating each of the compressors 21, 41, 51, and 71. The first controller
120 heating-controls the case heaters 21a, 41a, 51a, and 71a separately from each
other to thereby heat each of the compressors 21, 41, 51, and 71.
[0033] Furthermore, on the discharge side of each of the compressors 21, 41, 51, and 71,
each of temperature sensors S1 to S4 which are refrigerant temperature measuring units
is provided. Each of the temperature sensors S1 to S4 measures the temperature inside
each of the compressors 21, 41, 51, and 71 on the discharge side, and first controller
120 estimates the temperature of each of the compressors 21, 41, 51, and 71 on the
basis of each measured temperature. It should be noted that although when the operation
of each of the compressors 21, 41, 51, and 71 is in the stopped state, the refrigerant
is not discharged, it becomes possible to detect the temperature of the refrigerant
inside each of the compressors 21, 41, 51, and 71 by the temperature conducted by
heat conduction. The temperature values measured by the temperature sensors S1 to
S4 are used in the second and third embodiments to be described later.
[0034] The first controller 120 calculates, when the operation of each of the compressors
21, 41, 51, and 71 is in the stopped state, a temperature difference between the outdoor
air temperature measured by the outdoor air temperature measuring unit 150 and refrigerant
saturation temperature at the time of saturation of the refrigerant, determines the
energization ratio of the intermittent operation period on the basis of the above
calculation result and relationship stored in the first memory 121 described previously,
and executes the heating control of each of the compressors 21, 41, 51, and 71, i.e.,
each of the case heaters 21a, 41a, 51a, and 71a on the basis of the determined energization
ratio. Details of the heating control of the case heater to be executed by the first
controller 120 will be described later.
[0035] FIG. 4 is a view showing a relationship between a temperature difference between
the refrigerant saturation temperature and outdoor air temperature and enerigization
ratio r of the intermittent operation.
[0036] The first controller 120 acquires, when the operation of each of the compressors
21, 41, 51, and 71 is in the stopped state, the outdoor air temperature through the
outdoor air temperature measuring unit 150 and second controller 130, calculates the
temperature difference between the acquired outdoor air temperature and refrigerant
saturation temperature, and calculates the enerigization ratio of the intermittent
operation period from this temperature difference by utilizing the relationship shown
in FIG. 4. Then, on the basis of the energization ratio of the intermittent operation
period, the first controller 120 executes heating control of each of the case heaters
21a, 41a, 51a, and 71a.
[0037] Further, FIG. 5 is a view showing an example of an intermittent operation ratio.
[0038] In FIG. 5, the axis of ordinate indicates the on/off state of the heating control
of the case heater 21a, and axis of abscissas indicates time. The period Ts of the
intermittent operation is set at a predetermined time (for example, in this embodiment,
30 minutes), during the elapse of a first time period T1 which is a part of the predetermined
time, heating of the case heater 21a is kept in the off-state and, after the elapse
of the first time period T1 and during the elapse of a second time period T2, heating
of the case heater 21a is kept in the on-state. That is, the relationship between
the intermittent operation period Ts and time periods T1 and T2 is TS=T1+T2, and the
energization ratio r of the intermittent operation is T2/Ts. The first time period
T1 has a relationship "T1=(1-r)·Ts" with the intermittent operation period Ts and
ratio r, and second time period T2 has a relationship "T2=r·Ts" with the intermittent
operation period Ts and ratio r. It should be noted that such determination of the
first time period T1 and second time period T2 of the intermittent operation period
Ts, and intermittent operation ratio r is carried out also with respect to each of
the other case heaters 41a, 51a, and 71a in the same manner as above.
[0039] Next, intermittent operation control will be described below. FIG. 6 is flowchart
showing an example of the processing of intermittent operation control to be executed
by the first controller 120. This processing is executed at predetermined time intervals
and is executed each time, for example, one second elapses. It should be noted that
although this processing is executed with respect to each of the compressors 21, 41,
51, and 71, hereinafter, in order to simplify the description, only the processing
to be executed with respect to the compressor 21 will be described.
[0040] The first controller 120 determines whether or not the compressor 21 is in operation
(ST101). Upon determination that the compressor 21 is not in operation (ST101: NO),
the first controller 120 starts addition of an addition timer, calculates the energization
ratio r of the intermittent operation as described previously, and calculates the
first time period T1 and second time period T2 corresponding to the operation period
Ts and energization ratio r (ST102). Here, the addition timer is formed inside, for
example, the memory 121. This addition timer is used to determine whether or not the
current point in time is, for example, within the second time (second time period)
T2 after the elapse of the already-described first time (first time period) T1, i.e.,
to determine whether or not the heating control of the case heater 21a has already
been started.
[0041] Next, the first controller 120 determines whether or not the addition timer value
is greater than the already-described intermittent operation period Ts (ST103). Upon
determination that the addition timer value is less than the intermittent operation
period Ts (ST103: NO), the first controller 120 determines whether or not the addition
timer value is greater than the calculated first time period T1 (ST104). When the
addition timer value is less than the first time period T1 (ST104: NO), the first
controller 120 brings the case heater 21a into the off-state without carrying out
heating control (ST105), and returns to the determination (ST101) whether or not the
compressor 21 is in operation. Further, when the addition timer value is greater than
the first time period T1 (ST104: YES), the first controller 120 brings the case heater
21a into the on-state to thereby carry out heating control (ST106), and then returns
to the determination (ST101) whether or not the compressor 21 is in operation.
[0042] Then, the processing is returned to the processing (ST101) of determining whether
or not the compressor 21 is in operation and, when the compressor 21 is not in operation
(ST101: NO), the first controller 120 continues carrying out the heating control of
the case heater 21a until the addition timer value reaches the intermittent operation
period Ts. Then, when the addition timer value reaches the intermittent operation
period Ts (ST103: YES), the first controller 120 brings the case heater 21a into the
off-state, and resets the addition timer value (ST107). Then, the processing is returned
to the processing (ST101) of determining whether or not the compressor 21 is in operation,
and the above determination is repeated until the compressor 21 starts to operate.
[0043] It should be noted that when the compressor 21 is in operation or when the compressor
21 has started to operate (ST101: YES), the first controller 120 brings the case heater
21a into the off-state, resets the addition timer (ST107), and terminates the processing.
That is, while the compressor 21 is in operation, heating control of the case heater
21a is not executed.
[0044] Owing to the configuration described above, it is possible for the first controller
120 to acquire, when the operation of each of the compressors 21, 41, 51, and 71 is
in the stopped state, the outdoor air temperature measured by the outdoor air temperature
measuring unit 150, calculates the temperature difference between the acquired outdoor
air temperature and refrigerant saturation temperature, determine, on the basis of
the above calculation result and relationship stored in the first memory 120a, the
intermittent operation period Ts of each of the case heaters 21a, 41a, 51a, and 71a,
and execute heating control of each of the case heaters 21a, 41a, 51a, and 71a according
to each of the determined periods. The greater the temperature difference between
the refrigeration machine oil temperature and refrigerant saturation temperature,
the less the stagnation quantity of the refrigerant merging into the refrigeration
machine oil becomes and, the less the temperature difference, the greater the stagnation
quantity becomes. Further, when the operation of the refrigerating cycle is in the
stopped state, the refrigerant saturation temperature is dependent on the lower of
the outdoor air temperature which is the ambient temperature of the outdoor heat exchanger
and water temperature which is the temperature of the water heat exchanger. That is,
the refrigerant saturation temperature varies depending on the influence of the water
temperature or outdoor air temperature. On the other hand, the temperature of the
refrigeration machine oil lowers depending on the compressor ambient temperature.
That is, when the outdoor air temperature is low, the amount of heat radiation from
the compressor increases, and hence the case temperature is liable to lower. Accordingly,
although the case temperature of the compressor largely varies depending on the season,
there is sometimes a case where the variation in the temperature of water to be supplied
to the water heat exchanger is little throughout the year, and thus there is sometimes
a case where the refrigerant saturation temperature is not dependent on the outdoor
air temperature. As described above, in the heat source system configured to carry
out heat transfer to the utilization-side equipment by using a utilization-side fluid
such as water or the like as in the case of the air-cooling type heat pump chilling
unit, the stagnation quantity of the refrigerant merging into the refrigeration machine
oil increases/decreases due to the influence of the outdoor air temperature and water
temperature of the utilization-side equipment. For example, when the outdoor air temperature
is high and saturation temperature is low (water temperature is low), the temperature
difference between the refrigeration machine oil temperature and refrigerant saturation
temperature is great, whereby a condition making dilution difficult is given, and
hence the heat generation amount of the heater can be reduced.
[0045] By increasing/decreasing the energization ratio of each of the case heaters 21a,
41a, 51a, and 71a of each of the compressors 21, 41, 51, and 71 according to the temperature
difference between the refrigerant saturation temperature and outdoor air temperature
as in the case of the present application, it is possible to realize saving of energy
and optimization of the necessary energization time.
[0046] That is, even in an apparatus in which the temperature of water flowing into the
water heat exchanger 30 is approximately constant throughout the year due to the influence
of the usage on the utilization side or influence of the source of the supplied water,
it is possible to appropriately heat each of the compressors 21, 41, 51, and 71 by
each of the case heaters 21a, 41a, 51a, and 71a, appropriately prevent the refrigerant
stagnation phenomenon from occurring, and reduce the power consumption of the heating
control of each of the compressors 21, 41, 51, and 71.
[0047] Further, as described above, by calculating the operation ratio on the basis of the
temperature difference between the outdoor air temperature and refrigerant saturation
temperature, it is possible to carry out, throughout the year, a stable operation
imposing little load on the compressor and requiring only reduced power consumption
although the control to be carried out in the operation is simplified.
[0048] Further, the control described above is carried out, whereby it is possible to carry
out efficient heating control of the compressor saving power consumption without providing
a temperature sensor configured to measure the case temperature.
[0049] It should be noted that although in the above description, the method in which the
intermittent operation period Ts is made the predetermined time, and the first time
period during which energization is not to be carried out and second time period during
which energization is to be carried out are changed according to the energization
ratio r of the intermittent operation is used, in addition to this, the first time
period T1 may be made the fixed time, and intermittent operation period Ts and second
time period T2 may be changed according to the energization ratio r. Further, the
second time period T2 may be made the fixed time, and intermittent operation period
Ts and first time period T1 may be changed according to the energization ratio r.
When the first time period T1 and second time period T2 are determined according to
the energization ratio, each period may be made variable.
(Second Embodiment)
[0050] Although in the first embodiment, the processing of heating control of each of the
case heaters 21a, 41a, 51a, and 71a at the time when each of the compressors 21, 41,
51, and 71 is in the stopped state has been described, in a second embodiment, processing
at the time when each of the compressors 21, 41, 51, and 71 is started up will be
described. It should be noted that configurations identical to the first embodiment
are denoted by reference symbols identical to the first embodiment, and detailed descriptions
of these configurations are omitted.
[0051] FIG. 7 is a view showing an example of the configuration of a first controller 120
of the second embodiment. When compared with the first embodiment, the second embodiment
differs from the first embodiment in that a second area 123 is provided in a memory
121, and first startup pattern 125a and second startup pattern 125b are added to the
first controller 120.
[0052] The second area 123 stores therein a relationship between the temperature of each
of compressors 21, 41, 51, and 71 and refrigerant temperature (temperature sensor
value of the discharged gas) as first information. In this embodiment, the refrigerant
temperature is so made as to be acquired from each of temperature sensors S1 to S4
provided on the discharge side of each of the compressors 21, 41, 51, and 71, and
the first controller 120 can estimate the temperature of each of the compressors 21,
41, 51, and 71 from the refrigerant temperature measured in this way and already-described
first information. Furthermore, the first controller 120 is so made as to be able
to calculate a temperature difference between the above estimated temperature and
condensation temperature of each of the compressors 21, 41, 51, and 71 estimated from
the predetermined environmental conditions, and change the startup pattern of each
of the compressors 21, 41, 51, and 71 to one of the first startup pattern 125a and
second startup pattern 125b according to the calculated temperature difference.
[0053] The first startup pattern 125a is a startup pattern for securing the reliability.
That is, the first startup pattern 125a is a startup pattern in which each of the
compressors 21, 41, 51, and 71 is made to undergo a high-load operation after the
refrigeration machine oil is warmed by carrying out a warm-up operation. On the other
hand, the second startup pattern 125b is a normal startup pattern. That is, the second
startup pattern is a startup pattern in which each of the compressors 21, 41, 51,
and 71 is immediately made to undergo a high-load operation.
[0054] Next, startup control of the compressor will be described below. FIG. 8 is a view
showing an example of startup control of the compressor 21 to be executed by the first
controller 120. It should be noted that the same processing is to be described with
respect to each of the other compressors 41, 51, and 71, and hence in this embodiment,
descriptions will be given by taking the compressor 21 as an example.
[0055] First, the first controller 120 determines whether or not it has become the predetermined
time before the startup (ST201). When the determination is 'NO' (ST201: NO), the processing
is terminated. That is, until it becomes the predetermined time, a standby state is
continued.
[0056] Upon determination that it has become the predetermined time (ST201: YES), the first
controller 120 acquires the estimated value of the temperature of the compressor 21
(ST202). More specifically, the first controller 120 estimates the temperature of
the compressor 21 from the output value (refrigerant temperature) of the sensor S1
and first information stored in the second area 123, and acquires the estimation result
as the estimated value.
[0057] Next, the first controller 120 estimates the condensation temperature from the environmental
conditions such as the outdoor air temperature acquired from the outdoor air temperature
measuring unit 150, temperature of the cooling water, and the like, and acquires the
estimation result as the estimated value (ST203).
[0058] Next, the first controller 120 calculates a temperature difference between the estimated
value of the temperature of the compressor 21 and estimated value of the condensation
temperature (ST204), and determines whether or not the calculated temperature difference
exceeds a set value (ST205). Here, the set value is a threshold used to determine
the startup pattern for starting up the compressor 21 and is, for example, a value
stored in advance in the second area 123.
[0059] Upon determination that the temperature difference exceeds the set value (ST205:
YES), the first controller 120 starts up the compressor 21 in the first startup pattern
125a (ST206) and, upon determination that the temperature difference does not exceed
the set value (ST205: NO), the first controller 120 starts up the compressor 21 in
the second startup pattern 125b (ST207).
[0060] FIG. 9 is a view for explaining the two startup patterns. As shown in FIG. 9, the
startup patterns are contrived in such a manner that the operation of the compressor
21 is started after an elapse of a short time. Regarding the graphs g1 and g2 of the
temperature difference, whereas the graph g1 exceeds the set value with the elapse
of time, graph g2 does not exceed the set value. Accordingly, when the temperature
difference depicts the graph g1, a startup securing the reliability by the first startup
pattern 125a is needed and, when the temperature difference depicts the graph g2,
it becomes possible to carry out a startup in the second startup pattern 125b.
[0061] The first and second startup patterns 125a and 125b are configured as described above,
and hence even when a change occurs in the case temperature or condensation temperature
while the compressor 21 is in the stopped state, the first controller 120 can change
the startup pattern of the compressor 21 on the basis of whether or not the set value
set in advance is exceeded. Accordingly, when the set value is exceeded, by adopting
the first startup pattern 125a in which the high-load operation is executed after
a warm-up operation is carried out, it becomes possible to allow the dilution degree
of the refrigeration machine oil of the compressor 21 in the stopped state to be increased.
[0062] Further, the temperature of the compressor 21 is acquired from the temperature sensor
S1, and hence it is not necessary to provide a temperature sensor configured to measure
the temperature of the compressor 21 itself.
(Third Embodiment)
[0063] Although in the first embodiment, the processing of heating control of each of the
case heaters 21a, 41a, 51a, and 71a of each of the compressors 21, 41, 51, and 71
in the stopped state has been described, in a third embodiment, the processing to
be carried out when each of the compressors 21, 41, 51, and 71 is started up will
be described. It should be noted that configurations identical to the first embodiment
are denoted by reference symbols identical to the first embodiment, and detailed descriptions
of these configurations are omitted.
[0064] FIG. 10 is a view showing an example of the configuration of a first controller 120
of the third embodiment. When compared with the first embodiment, the third embodiment
differs from the first embodiment in that a third area 124 is provided in a memory
121, and third startup pattern 125c and fourth startup pattern 125d are added to the
first controller 120.
[0065] The third area 124 stores therein a relationship between the temperature of each
of compressors 21, 41, 51, and 71 and refrigerant temperature (temperature sensor
value of the discharged gas) as first information. In this embodiment, as in the case
of the second embodiment, the refrigerant temperature is so made as to be acquired
from each of temperature sensors S1 to S4 provided on the discharge side of each of
the compressors 21, 41, 51, and 71, and the first controller 120 can estimate the
temperature of each of the compressors 21, 41, 51, and 71 from the refrigerant temperature
acquired in the manner described above and already-described first information. Furthermore,
the first controller 120 is so made as to be able to estimate the temperature of each
of the compressors 21, 41, 51, and 71 from the refrigerant temperature to be measured
and first information, calculate a temperature difference between the estimated temperature
and refrigerant saturation temperature, and change the startup pattern of each of
the compressors 21, 41, 51, and 71 to one of the third startup pattern 125c and fourth
startup pattern 125d according to whether or not the calculated temperature difference
becomes less than a set value.
[0066] The third startup pattern 125c is, as in the case of the first startup pattern 125a,
a startup pattern for securing the reliability. That is, the third startup pattern
125c is a startup pattern in which each of the compressors 21, 41, 51, and 71 is made
to undergo a high-load operation after the refrigeration machine oil is warmed by
carrying out a warm-up operation. On the other hand, the fourth startup pattern 125d
is, as in the case of the second startup pattern 125b, a normal startup pattern. That
is, the fourth startup pattern is a startup pattern in which each of the compressors
21, 41, 51, and 71 is immediately made to undergo a high-load operation.
[0067] Next, startup control of the compressor will be described below. FIG. 11 is a view
showing an example of startup control of the compressor 21 to be executed by the first
controller 120. It should be noted that the same processing is to be described with
respect to each of the other compressors 41, 51, and 71, and hence in this embodiment,
descriptions will be given by taking the compressor 21 as an example.
[0068] First, the first controller 120 determines whether or not the compressor 21 is in
the stopped state (ST301). When the determination result is 'NO' (ST301: NO), the
processing is terminated. That is, this control is not executed while the compressor
21 is in operation.
[0069] Upon determination that the compressor 21 is in the stopped state (ST301: YES), the
first controller 120 acquires an estimated value of the case temperature of the compressor
21 (ST302). The first controller 120 estimates the temperature of the compressor 21
from an output value (refrigerant temperature) of the sensor S1 and first information
stored in the third area 124, and acquires the estimation result as the estimated
value.
[0070] Next, the first controller 120 acquires the refrigerant saturation temperature stored
in the first memory 120a (ST303), and calculates the temperature difference between
these temperatures (ST304). The temperature differences are stored in sequence in,
for example, the third area 124.
[0071] Next, the first controller 120 determines whether or not the compressor 21 is to
be started (ST305). That is, it is determined whether or not it has become the time
for which the startup of the compressor 21 is scheduled. When it is determined by
the first controller 120 that the compressor 21 is not to be started (ST305: NO),
the processing is returned to step ST302. That is the processing of calculating the
temperature difference is executed until the compressor 21 is started up.
[0072] On the other hand, upon determination that the compressor 21 is to be started (ST305:
YES), the first controller 120 determines whether or not the temperature difference
has become less than the set value (ST306). That is, it is determined whether or not
there has been a case where the already-described temperature difference has become
less than the set value set in advance before the startup of the compressor 21.
[0073] Upon determination that there has been the case where the temperature difference
has become less than the set value (ST306: YES), the first controller 120 starts up
the compressor 21 in the third startup pattern 125c (ST307) and, upon determination
that there has not been the case where the temperature difference has become less
than the set value (ST306: NO), the first controller 120 starts up the compressor
21 in the fourth startup pattern 125d (ST308).
[0074] Owing to the configuration described above, even when a change in the environmental
conditions occurs while the compressor 21 is in the stopped state, it is possible
for the first controller 120 to change the startup pattern of the compressor 21 on
the basis of whether or not there has been the case where the temperature difference
has become less than the set value. Accordingly, when there has been the case where
the temperature difference has become less than the set value, by adopting the third
startup pattern 125c in which the high-load operation is executed after a warm-up
operation is carried out, it becomes possible to allow the dilution degree of the
refrigeration machine oil of the compressor 21 in the stopped state to be increased.
[0075] Further, the temperature of the compressor 21 is acquired from the temperature sensor
S1, and hence it is not necessary to provide a temperature sensor configured to measure
the temperature of the compressor 21 itself, this being identical to the second embodiment.
[0076] While certain embodiments have been described, these embodiments have been presented
by way of example only, and are not intended to limit the scope of the inventions.
Indeed, the novel embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in the form of the
embodiments described herein may be made without departing from the spirit of the
inventions. The accompanying claims and their equivalents are intended to cover such
forms or modifications as would fall within the scope and spirit of the inventions.
Reference Signs List
[0077] 10 ··· air-cooling type heat pump chilling device, 11, 12, 13 ··· air-cooling type
heat pump chilling unit, 11a to 11d, 12a to 12d, 13a to 13d ··· circuit, 21, 41, 51,
71 ··· compressor, 21a, 41a, 51a, 71a ··· case heater, 120 ··· first controller, 121
··· memory, 122 ··· first area, 123 ··· second area, 124 ··· third area, 125a ···
first startup pattern, 125b ··· second startup pattern, 125c ... third startup pattern,
125d ··· fourth startup pattern, 130 ··· second controller, 150 ··· outdoor air temperature
measuring unit, and T1, T2 ··· time.