U.S. patent application number 12/524369 was filed with the patent office on 2009-12-24 for refrigeration unit for refrigerated vehicle.
Invention is credited to Yuji Fujimoto, Shigeichi Kitano, Sumikazu Matsuno, Yukio Nishihama, Yuzou Sawada.
Application Number | 20090314019 12/524369 |
Document ID | / |
Family ID | 39644523 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090314019 |
Kind Code |
A1 |
Fujimoto; Yuji ; et
al. |
December 24, 2009 |
REFRIGERATION UNIT FOR REFRIGERATED VEHICLE
Abstract
A sub-engine (30), a compressor (40) driven by the sub-engine
(30), and a refrigeration circuit (70) connected to the compressor
(40) and operable in a vapor compression refrigeration cycle are
provided, and the interior of a refrigerator (13) of a refrigerated
vehicle (10) is cooled. A rotational speed control unit (91) for
linearly controlling fluctuations in the rotational speed of the
sub-engine (30) such that the refrigeration capacity grows or
declines in response to a refrigeration load is provided. A battery
(51) for storing electric power and an electric generator (50) for
generating electric power by the rotational drive of the
refrigerating engine (30) to store the generated electric power in
the battery (51) are provided. A fan motor (7a) for the
refrigeration circuit (70) is selectively connectable to the
electric generator (50) and the battery (51) such that power is fed
from one of the electric generator (50) and the battery (51) to the
fan motor (7a).
Inventors: |
Fujimoto; Yuji; (Osaka,
JP) ; Nishihama; Yukio; (Osaka, JP) ; Kitano;
Shigeichi; (Osaka, JP) ; Sawada; Yuzou;
(Osaka, JP) ; Matsuno; Sumikazu; (Shiga,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
39644523 |
Appl. No.: |
12/524369 |
Filed: |
January 24, 2008 |
PCT Filed: |
January 24, 2008 |
PCT NO: |
PCT/JP2008/050975 |
371 Date: |
July 24, 2009 |
Current U.S.
Class: |
62/228.5 ;
62/236; 62/323.3; 62/510 |
Current CPC
Class: |
B60H 1/3222 20130101;
B60H 1/3226 20130101; F25D 29/003 20130101; B60P 3/20 20130101;
B60H 1/3232 20130101; F25B 27/00 20130101 |
Class at
Publication: |
62/228.5 ;
62/236; 62/323.3; 62/510 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F25B 27/00 20060101 F25B027/00; F25B 1/10 20060101
F25B001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 26, 2007 |
JP |
2007-016342 |
Claims
1. A refrigerated vehicle refrigeration unit for cooling the
interior of a refrigerator (13) of a refrigerated vehicle (10), the
refrigeration unit including: a refrigerating engine (30); a
compressor (40) driven by the refrigerating engine (30); and a
refrigeration circuit (70) connected to the compressor (40) and
operable in a vapor compression refrigeration cycle, wherein the
refrigerated vehicle refrigeration unit comprises a rotational
speed controller (91) for linearly controlling fluctuations in a
rotational speed of the refrigerating engine (30) such that a
refrigeration capacity grows or declines in response to a
refrigeration load.
2. A refrigerated vehicle refrigeration unit for cooling the
interior of a refrigerator (13) of a refrigerated vehicle (10), the
refrigeration unit including: a refrigerating engine (30); a
compressor (40) driven by the refrigerating engine (30); and a
refrigeration circuit (70) connected to the compressor (40) and
operable in a vapor compression refrigeration cycle, wherein the
refrigerated vehicle refrigeration unit comprises a battery (51)
for storing electric power; and an electric generator (50) for
generating electric power by the rotational drive of the
refrigerating engine (30) to store the generated electric power in
the battery (51) and rotating by the electric power of the battery
(51) to develop torque, and the refrigerating engine (30) is
disconnectably connected to the compressor (40), and the electric
generator (50) is connected to the compressor (40).
3. The refrigerated vehicle refrigeration unit of claim 1 further
comprising: a battery (51) for storing electric power; and an
electric generator (50) for generating electric power by the
rotational drive of the refrigerating engine (30) to store the
generated electric power in the battery (51), wherein a fan motor
(7a) for the refrigeration circuit (70) is selectively connectable
to the electric generator (50) and the battery (51) such that power
is fed from at least one of the electric generator (50) and the
battery (51) to the fan motor (7a).
4. The refrigerated vehicle refrigeration unit of claim 1 further
comprising: a battery (51) for storing electric power; and an
electric generator (50) for generating electric power by the
rotational drive of the refrigerating engine (30) to store the
generated electric power in the battery (51) and rotating by the
electric power of the battery (51) to develop torque, wherein the
refrigerating engine (30) is disconnectably connected to the
compressor (40), and the electric generator (50) is disconnectably
connected to the compressor (40).
5. The refrigerated vehicle refrigeration unit of claim 1 or 2,
wherein the compressor (40) comprises a plurality of compressors
(40), and the plurality of compressors (40) are connected in
parallel and connected to the refrigeration circuit (70).
6. The refrigerated vehicle refrigeration unit of claim 1 or 2
further comprising an auxiliary motor (60) disconnectably connected
to the compressor (40) and driven by electric power of an external
power source.
7. The refrigerated vehicle refrigeration unit of claim 2 or 3,
wherein the electric generator (50) is selectively connectable to
an external power source and the battery (51).
Description
TECHNICAL FIELD
[0001] The present invention relates to refrigeration units for
refrigerated vehicles, and more particularly relates to a
refrigeration unit configured to drive a compressor directly by a
refrigerating engine.
BACKGROUND ART
[0002] As described in Patent Document 1, refrigerated vehicles
configured so that a trailer forming a refrigerator is towed by a
tractor have conventionally been equipped with a refrigeration unit
for cooling the interior of a refrigerator. A refrigerated vehicle
of this type has been equipped with a sub-engine forming a
refrigerating engine separate from a driving engine. For the
refrigeration unit, a compressor is coupled to the sub-engine, and
a refrigeration circuit is connected to the compressor. The
compressor is driven by the sub-engine, and an evaporator of the
refrigeration circuit evaporates refrigerant, resulting in cooling
of the interior of the refrigerator.
Patent Document 1: Japanese Unexamined Patent Application
Publication No. 2006-234198
DISCLOSURE OF INVENTION
Problems that the Invention is to Solve
[0003] For conventional refrigeration units for refrigerated
vehicles, their refrigeration capacities are generally merely
controlled in two stages. Hence, the conventional refrigeration
units have not adapted to fluctuations in their refrigeration loads
and thus have been inefficient.
[0004] More particularly, the operational capacity of the
compressor has been only changed in two stages by controlling the
rotational speed of the sub-engine in two stages. Consequently,
even with a linear change in the refrigeration load, the
refrigeration capacity has only changed in two stages. Therefore,
the conventional refrigeration units have had a region providing an
unnecessary capacity and thus have exhibited poor refrigeration
efficiency.
[0005] The present invention has been made in view of the foregoing
point and an object thereof is to improve the refrigeration
efficiency of a refrigeration unit by efficiently providing the
refrigeration capacity thereof.
Means of Solving the Problems
[0006] A first aspect of the invention is directed to a
refrigerated vehicle refrigeration unit configured to cool the
interior of a refrigerator (13) of a refrigerated vehicle (10) and
including: a refrigerating engine (30); a compressor (40) driven by
the refrigerating engine (30); and a refrigeration circuit (70)
connected to the compressor (40) and operable in a vapor
compression refrigeration cycle. The refrigerated vehicle
refrigeration unit includes a rotational speed controller (91) for
linearly controlling fluctuations in a rotational speed of the
refrigerating engine (30) such that a refrigeration capacity grows
or declines in response to a refrigeration load.
[0007] A second aspect of the invention is directed to a
refrigerated vehicle refrigeration unit configured to cool the
interior of a refrigerator (13) of a refrigerated vehicle (10) and
including: a refrigerating engine (30); a compressor (40) driven by
the refrigerating engine (30); and a refrigeration circuit (70)
connected to the compressor (40) and operable in a vapor
compression refrigeration cycle. The refrigerated vehicle
refrigeration unit includes a battery (51) for storing electric
power; and an electric generator (50) for generating electric power
by the rotational drive of the refrigerating engine (30) to store
the generated electric power in the battery (51) and rotating by
the electric power of the battery (51) to develop torque.
Additionally, the refrigerating engine (30) is disconnectably
connected to the compressor (40), and the electric generator (50)
is connected to the compressor (40).
[0008] In a third aspect of the invention, the refrigerated vehicle
refrigeration unit according to the first aspect of the invention
may further include: a battery (51) for storing electric power; and
an electric generator (50) for generating electric power by the
rotational drive of the refrigerating engine (30) and allowing the
battery (51) to store the generated electric power. A fan motor
(7a) for the refrigeration circuit (70) may be selectively
connectable to the electric generator (50) and the battery (51)
such that power is fed from at least one of the electric generator
(50) and the battery (51) to the fan motor (7a).
[0009] In a fourth aspect of the invention, the refrigerated
vehicle refrigeration unit according to the first aspect of the
invention may further include: a battery (51) for storing electric
power; and an electric generator (50) for generating electric power
by the rotational drive of the refrigerating engine (30) to store
the generated electric power in the battery (51) and rotating by
the electric power of the battery (51) to develop torque. The
refrigerating engine (30) may be disconnectably connected to the
compressor (40), and the electric generator (50) may be
disconnectably connected to the compressor (40).
[0010] In a fifth aspect of the invention, in the refrigeration
unit according to any one of the first through fourth aspects of
the invention, the compressor (40) may include a plurality of
compressors (40), and the plurality of compressors (40) may be
connected in parallel and connected to the refrigeration circuit
(70).
[0011] In a sixth aspect of the invention, the refrigeration unit
according to any one of the first through fourth aspects of the
invention may further include an auxiliary motor (60)
disconnectably connected to the compressor (40) and driven by
electric power of an external power source.
[0012] In a seventh aspect of the invention, in the refrigeration
unit according to the second or third aspect of the invention, the
electric generator (50) may be selectively connectable to an
external power source and the battery (51).
[0013] <Operation>
[0014] According to the first aspect of the invention, the
compressor (40) is driven by the torque of the refrigerating engine
(30), and the refrigeration circuit (70) performs a cooling
operation, thereby cooling the interior of the refrigerator (13).
When the refrigeration load of the refrigerator (13) fluctuates,
the rotational speed controller (91) linearly controls the
rotational speed of the refrigerating engine (30) in response to
the fluctuations in the load, resulting in improved efficiency.
[0015] According to the second aspect of the invention, the
compressor (40) is driven by the torque of the refrigerating engine
(30), and the refrigeration circuit (70) performs a cooling
operation, thereby cooling the interior of the refrigerator (13).
Meanwhile, for example, if the refrigeration load is small, the
refrigerating engine (30) is stopped while the electric power of
the battery (51) allows the electric generator (50) to rotate. This
rotation drives the compressor (40). In this way, the cooling
operation of the refrigeration circuit (70) is achieved.
[0016] In the third aspect of the invention, the fan motor (7a) for
the refrigeration circuit (70) rotates by the electric power of the
electric generator (50) or the battery (51). In particular, the
compressor (40) is stopped, and the cooling of the interior of the
refrigerator (13) is continued only by the fan motor (7a).
[0017] In the fourth aspect of the invention, the compressor (40)
is driven in a low rotational speed range of the refrigerating
engine (30) or any other range by the electric power of the battery
(51).
[0018] In the fifth aspect of the invention, the number of the
plurality of compressors (40) is controlled, thereby controlling
the refrigeration capacity.
[0019] In the sixth aspect of the invention, if the refrigerating
engine (30) cannot be driven, the compressor (40) is driven by the
auxiliary motor (60). In this way, the cooling operation of the
refrigeration circuit (70) is achieved.
[0020] In the seventh aspect of the invention, if the refrigerating
engine (30) cannot be driven, the electric generator (50) drives
the compressor (40). In this way, the cooling operation of the
refrigeration circuit (70) is achieved.
ADVANTAGES OF THE INVENTION
[0021] According to the above-described present invention,
fluctuations in the rotational speed of the refrigerating engine
(30) are linearly controlled so that the refrigeration capacity
grows or declines in response to the refrigeration load. Therefore,
an unnecessary refrigeration capacity is not provided, for example,
as compared with the conventional case in which the rotational
speed of a refrigerating engine is controlled in two stages. This
improves cooling efficiency, resulting in energy savings.
[0022] Furthermore, as compared with a unit that is
volume-controlled by driving an electric generator using a
refrigerating engine (30) and driving a motor of a compressor (40)
using the power of this electric generator as in the past, losses
arising from motor efficiency, power losses from the electric
generator to the motor, or other losses are not caused. This
improves the efficiency of the refrigeration unit.
[0023] According to the second aspect of the invention, since the
electric generator (50) and the battery (51) are provided, the
refrigerating engine (30) is driven at a constant rotational speed.
Meanwhile, if the refrigeration load is reduced, the refrigerating
engine (30) is stopped, the electric power stored in the battery
(51) allows the electric generator (50) to develop torque, and the
rotation of the electric generator (50) drives the compressor (40).
Consequently, the power of the refrigerating engine (30) and the
electric power of the battery (51) can be selectively used. This
can provide the refrigeration capacity matched with the
refrigeration load while permitting energy savings, resulting in
improved efficiency.
[0024] According to the third aspect of the invention, the electric
power generated by the electric generator (50) drives the fan motor
(7a). Therefore, the fan motor (7a) can form an alternating motor,
resulting in improved efficiency.
[0025] Moreover, if the refrigeration load is small, the rotation
of the refrigerating engine (30) is stopped, and only the fan motor
(7a) is driven by the electric power stored in the battery (51),
thereby maintaining the indoor temperature only by an air blowing
operation. As a result, the operating time of the refrigerating
engine (30) can be reduced.
[0026] According to the fourth aspect of the invention, in a low
rotational speed range of the refrigerating engine (30), the
refrigerating engine (30) is stopped, the electric power stored in
the battery (51) allows the electric generator (50) to develop
torque, and the rotation of the electric generator (50) can drive
the compressor (40). In other words, the electric generator (50)
can double as a motor to drive the compressor (40). Consequently,
the refrigerating engine (30) can be used in its high-efficiency
range, resulting in further energy savings.
[0027] According to the fifth aspect of the invention, since the
refrigeration unit is equipped with the plurality of compressors
(40), the number of operating one or ones of the compressors (40)
is controlled, thereby extensively adjusting the refrigeration
capacity in response to the rotational speed range of the
refrigerating engine (30). This adjustment allows the refrigeration
capacity to adapt to extensive refrigeration loads.
[0028] According to the sixth aspect of the invention, since the
auxiliary motor (60) is provided, an operation of the refrigeration
circuit (70) can be continued, for example, also during the stop
period of the sub-engine (30). This can increase the range of use
for the refrigeration unit.
[0029] According to the seventh aspect of the invention, the
electric generator (50) is selectively connectable to an external
power source and the battery (51). Therefore, the electric
generator (50) can double as a motor. As a result, the number of
components can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is a side view showing a refrigerated vehicle.
[0031] FIG. 2 is a block diagram showing the configuration of a
refrigeration unit.
DESCRIPTION OF CHARACTERS
[0032] 10 refrigerated vehicle [0033] 13 trailer body
(refrigerator) [0034] 20 refrigeration unit [0035] 30 sub-engine
(refrigerating engine) [0036] 40 compressor [0037] 50 electric
generator [0038] 51 battery [0039] 60 standby motor (auxiliary
motor) [0040] 70 refrigeration circuit [0041] 7a fan motor
BEST MODE FOR CARRYING OUT THE INVENTION
[0042] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings.
[0043] As shown in FIG. 1, a refrigerated vehicle (10) of this
embodiment includes a trailer (11) and a tractor (12) for towing
the trailer (11) and is used to transport refrigerated food
products, such as frozen food products or perishable food products,
by land.
[0044] The trailer (11) includes a trailer body (13), i.e., a
refrigerator, and a refrigeration unit (20) for a trailer, i.e., a
refrigeration unit for a refrigerated vehicle. The refrigeration
unit (20) is placed on the front end surface of the trailer body
(13), i.e., the surface thereof near the tractor (12).
[0045] As shown in FIG. 2, the refrigeration unit (20) includes a
sub-engine (30) forming a refrigerating engine, two compressors
(40), a refrigeration circuit (70), an electric generator (50), a
battery (51), and a standby motor (60) forming an auxiliary
motor.
[0046] The sub-engine (30) is provided separately from a driving
engine and configured as an exclusive engine for driving the
refrigeration unit (20) so that a belt (21) is wound around a
pulley (31) fitted onto a drive shaft of the sub-engine (30).
[0047] The compressors (40) are scroll compressors and configured
as so-called open compressors so that pulleys (41) fitted onto
respective drive shafts of the compressors (40) are coupled through
the belt (21) to the pulley (31) of the sub-engine (30). In other
words, the compressors (40) are mechanically coupled to the
sub-engine (30) and driven by the torque of the sub-engine (30).
Although not shown, the pulleys (41) or other components for the
compressors (40) are provided with disconnecting mechanisms, such
as clutches. Thus, the compressors (40) are disconnectably coupled
to the sub-engine (30).
[0048] A refrigerant pipe (71) for the refrigeration circuit (70)
operable in a vapor compression refrigeration cycle is coupled to
the compressors (40). The two compressors (40) are connected in
parallel to the refrigeration circuit (70).
[0049] Although not shown, the refrigeration circuit (70) includes
a condenser, an expansion mechanism, and an evaporator. Refrigerant
circulates in the following manner: Refrigerant discharged from the
compressors (40) is condensed by the condenser, decompressed by the
expansion mechanism, then evaporated by the evaporator, and
returned to the compressors (40). The indoor air of the trailer
body (13) is cooled by the evaporator, thereby cooling the interior
of the trailer body (13).
[0050] Furthermore, the refrigeration circuit (70) includes fans
(72) for the condenser and evaporator. Fan motors (7a) are coupled
to the fans (72).
[0051] For the electric generator (50), a pulley (52) fitted onto a
drive shaft of the electric generator (50) is coupled through
another belt (21) to the pulley (31) of the sub-engine (30). The
electric generator (50) generates electric power by the torque of
the sub-engine (30). Although not shown, the pulley (52) or any
other component for the electric generator (50) is provided with a
disconnecting mechanism, such as a clutch. Thus, the electric
generator (50) is disconnectably coupled to the sub-engine
(30).
[0052] The battery (51) is connected to the electric generator (50)
to store the power generated by the electric generator (50).
[0053] The electric generator (50) is electrically wired to the fan
motors (7a) so that the fan motors (7a) are driven by the electric
power generated by the electric generator (50). Furthermore, the
fan motors (7a) are electrically wired also to the battery (51) and
selectively connected to the electric generator (50) and the
battery (51) so as to be driven by at least one of the electric
power from the electric generator (50) and the electric power from
the battery (51).
[0054] The fan motors (7a) are formed of alternating motors. The
direct-current power supplied from the electric generator (50) and
the battery (51) is converted into alternating-current power, and
then the resultant alternating-current power is supplied to the fan
motors (7a).
[0055] Furthermore, the electric generator (50) and the battery
(51) feed power also to control devices.
[0056] The standby motor (60) is connectable to an external power
source and permits a freezing operation of the refrigeration
circuit (70) also during the period during which the refrigerated
vehicle (10) is parked in a garage or the like. For the standby
motor (60), a pulley (61) fitted onto a drive shaft of the standby
motor (60) is coupled through the associated belt (21) to the
pulley (31) of the sub-engine (30) so as to be coupled to the
compressors (40). The pulley (61) or any other component for the
standby motor (60) is provided with a disconnecting mechanism, such
as a clutch. Thus, the standby motor (60) is disconnectably coupled
to the compressors (40). In other words, the standby motor (60)
drives the compressors (40) during the stop period of the
sub-engine (30) and is formed of a compact motor capable of
rotating at high speed.
[0057] A controller (90) is connected to the sub-engine (30) and
provided with a rotational speed control unit (91) forming a
rotational speed controller for the sub-engine (30). The rotational
speed control unit (91) controls the rotational speed of the
sub-engine (30). In other words, the rotational speed controller is
configured, for example, to control a throttle motor for driving a
throttle valve of the sub-engine (30).
[0058] Furthermore, the rotational speed control unit (91) linearly
controls fluctuations in the rotational speed of the sub-engine
(30) such that the refrigeration capacity of the refrigeration unit
grows or declines in response to the refrigeration load. More
particularly, the rotational speed control unit (91) linearly
increases the rotational speed of the sub-engine (30) on the basis
of, for example, the temperature differential between an indoor
temperature and a desired temperature in the following manner: With
an increase in the temperature differential and an associated
increase in the refrigeration load, the refrigeration capacity
grows. Conversely, the rotational speed control unit (91) linearly
decreases the rotational speed of the sub-engine (30), for example,
in the following manner: With a decrease in the temperature
differential between the indoor temperature and the desired
temperature and an associated decrease in the refrigeration load,
the refrigeration capacity declines.
[0059] -Operational Behavior--
[0060] Next, a description will be given of the behavior of the
above-described refrigeration unit (20) for the refrigerated
vehicle (10) during a cooling operation thereof.
[0061] First, when the sub-engine (30) is driven separately from
the driving engine, the torque of the sub-engine (30) is
transmitted through the associated belt (21) to the compressors
(40). Thus, the rotation of the sub-engine (30) permits the
rotational drive of the two compressors (40). The rotational drive
of the compressors (40) allows the compressors (40) to compress
refrigerant in the refrigeration circuit (70). The refrigerant
circulates in the following manner: The refrigerant discharged from
the compressors (40) is condensed by the condenser, decompressed by
the expansion mechanism, then evaporated by the evaporator, and
returned to the compressors (40). The indoor air of the trailer
body (13) is cooled by the evaporator, thereby cooling the interior
of the trailer body (13).
[0062] Meanwhile, although not shown, the temperature of the indoor
air of the trailer body (13) is sensed, thereby detecting the
refrigeration load on the basis of the temperature differential
between the indoor temperature and the desired temperature. When
the temperature differential between the indoor temperature and the
desired temperature becomes greater and the refrigeration load
accordingly increases, the rotational speed control unit (91)
linearly increases the rotational speed of the sub-engine (30) so
that, with the increase in the temperature differential, the
refrigeration capacity grows. On the other hand, when the
temperature differential between the indoor temperature and the
desired temperature becomes smaller and the refrigeration load
accordingly decreases, the rotational speed control unit (91)
linearly decreases the rotational speed of the sub-engine (30) so
that, with the decrease in the temperature differential, the
refrigeration capacity declines.
[0063] Consequently, the cooling capacity grows in response to the
increase in the refrigeration load, resulting in reliable cooling
of the interior of the trailer body (13).
[0064] Furthermore, the refrigeration capacity is controlled in the
following manner: If the refrigeration load is small, only one of
the two compressors (40) is driven, and if the refrigeration load
is large, both of the two compressors (40) are driven.
[0065] Meanwhile, the rotation of the sub-engine (30) allows the
electric generator (50) to generate electric power. The electric
power of the electric generator (50) is supplied to the fan motors
(7a), thereby driving the fans (72). The generated electric power
of the electric generator (50) is fed also to control devices, such
as the controller (90), and fed also to the battery (51) so as to
be stored therein.
[0066] On condition that a freezing operation of the refrigeration
circuit (70) is performed also during the period during which the
refrigerated vehicle (10) is parked in a garage or the like, the
standby motor (60) is connected to an external power source. The
drive of the standby motor (60) allows the torque of the standby
motor (60) to drive the compressors (40). As a result, the
refrigeration circuit (70) continues its cooling operation. In this
case, while the coupling between the compressors (40) and the
sub-engine (30) is interrupted, the standby motor (60) is coupled
to the compressors (40).
[0067] -Advantages of Embodiment--
[0068] As described above, according to this embodiment,
fluctuations in the rotational speed of the sub-engine (30) are
linearly controlled so that the refrigeration capacity grows or
declines in response to the refrigeration load. Therefore, an
unnecessary refrigeration capacity is not provided, for example, as
compared with the conventional case in which the rotational speed
of a sub-engine is controlled in two stages. This improves cooling
efficiency, resulting in energy savings.
[0069] Furthermore, as compared with a unit that is
volume-controlled by driving an electric generator using a
sub-engine (30) and driving a motor of a compressor (40) using the
power of this electric generator as in the past, losses arising
from motor efficiency, power losses from the electric generator to
the motor, or other losses are not caused. This improves the
efficiency of the refrigeration unit.
[0070] Moreover, since the refrigeration unit is equipped with the
two compressors (40), the number of operating one or ones of the
compressors (40) is controlled, thereby extensively adjusting the
refrigeration capacity in response to the rotational speed range of
the sub-engine (30). This adjustment allows the refrigeration
capacity to adapt to extensive refrigeration loads.
[0071] In addition, the electric power generated by the electric
generator (50) drives the fan motors (7a). Therefore, the fan
motors (7a) can form alternating motors, resulting in improved
efficiency.
[0072] Furthermore, since the standby motor (60) is provided, an
operation of the refrigeration circuit (70) can be continued, for
example, also during the stop period of the sub-engine (30). This
can increase the range of use for the refrigeration unit.
[0073] <Other Embodiments>
[0074] The above embodiment of the present invention may be
configured as follows.
[0075] In the above embodiment, the compressors (40) are always
driven during the cooling operation. However, if the refrigeration
load is small, the rotation of the sub-engine (30) may be stopped,
and only the fan motors (7a) may be driven by the electric power
stored in the battery (51), thereby maintaining the indoor
temperature only by an air blowing operation. As a result, the
operating time of the sub-engine (30) can be reduced.
[0076] In a low rotational speed range of the sub-engine (30), the
sub-engine (30) may be stopped, the electric power stored in the
battery (51) may allow the electric generator (50) to develop
torque, and the rotation of the electric generator (50) may drive
the compressors (40). In other words, the electric generator (50)
may double as a motor to drive the compressors (40). In this case,
coupling between the compressors (40) and the sub-engine (30) is
interrupted. Consequently, the sub-engine (30) can be used in its
high-efficiency range, resulting in further energy savings.
[0077] Although in the above embodiment the rotational speed
control unit (91) is provided, the rotational speed control unit
(91) may be omitted. More particularly, the sub-engine (30) may be
driven at a constant rotational speed. Meanwhile, if the
refrigeration load is reduced, the sub-engine (30) may be stopped,
the electric power stored in the battery (51) may allow the
electric generator (50) to develop torque, and the rotation of the
electric generator (50) may drive the compressors (40). In this
case, the power of the sub-engine (30) and the electric power of
the battery (51) can be selectively used. This provides the
refrigeration capacity matched with the refrigeration load while
permitting energy savings, resulting in improved efficiency.
[0078] Although in the above embodiment the electric generator (50)
and the standby motor (60) are both provided, the electric
generator (50) may double as the standby motor (60). In other
words, the electric generator (50) may be selectively connectable
to an external power source and the battery (51). As a result, the
number of components can be reduced.
[0079] Although in the above embodiment the two compressors (40)
are provided, a single compressor (40) may be provided in the
present invention. Alternatively, three or more compressors (40)
may be provided.
[0080] Although in the above embodiment the standby motor (60) is
provided, it does not always need to be provided in the first,
second and other aspects of the invention. In other words, the
standby motor (60) may be provided as an optional item.
[0081] Although in the above embodiment the refrigerated vehicle
(10) having a trailer was described, the refrigerated vehicle (10)
may be a refrigerated truck or any other refrigerated vehicle.
[0082] The above embodiments are mere essentially preferable
examples, and are not intended to limit any scopes of the present
invention, applicable subjects, and usage.
INDUSTRIAL APPLICABILITY
[0083] As described above, the present invention is useful for
refrigeration units for refrigerated vehicles for cooling, for
example, the indoor air in the interior of a trailer body.
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