GB2269684A - Refrigerator compressor output control - Google Patents

Refrigerator compressor output control Download PDF

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Publication number
GB2269684A
GB2269684A GB9315007A GB9315007A GB2269684A GB 2269684 A GB2269684 A GB 2269684A GB 9315007 A GB9315007 A GB 9315007A GB 9315007 A GB9315007 A GB 9315007A GB 2269684 A GB2269684 A GB 2269684A
Authority
GB
United Kingdom
Prior art keywords
temperature
compressor
unit
chilled
water outlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9315007A
Other versions
GB9315007D0 (en
GB2269684B (en
Inventor
Tetsuo Shimode
Yoshikazu Amo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Publication of GB9315007D0 publication Critical patent/GB9315007D0/en
Publication of GB2269684A publication Critical patent/GB2269684A/en
Application granted granted Critical
Publication of GB2269684B publication Critical patent/GB2269684B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
    • F24F5/0003—Exclusively-fluid systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/022—Compressor control arrangements
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device
    • G05D23/1912—Control of temperature characterised by the use of electric means using an analogue comparing device whose output amplitude can take more than two discrete values
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/02—Compressor control
    • F25B2600/025—Compressor control by controlling speed
    • F25B2600/0251—Compressor control by controlling speed with on-off operation

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Thermal Sciences (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

In an arrangement to regulate the temperature of the working fluid in a refrigerating apparatus, the compressor is set to operate at one of a number of levels in dependence upon the temperature of the fluid at the outlet and inlet of the refrigeration means. The temperature range of the working fluid is divided into a number of zones each having an associated compressor output including a compressor off level and the compressor is set to operate at the level corresponding to the sensed outlet temperature. When the compressor has been shut off, it is only restarted when the inlet temperature exceeds one of the zone boundaries thus producing a hysteresis effect. <IMAGE>

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a temperature controller of a refrigerating apparatus which incorporates a compressor including a capacity control unit having a plurality of steps and which is required to feed chilled (or hot) water within a predetermined range of temperature.
Description of the Related Art Conventionally, the chilled (or hot) water outlet temperature can be controlled precisely by the following methods. For example, a compressor having a continuous control unit is controlled by a continuous controller, or a heat exchanger is arranged in the chilled (or hot) water outlet system for heat-exchanging with another refrigerant so as to control the outlet temperature more precisely by the refrigerant heat (Japanese Patent Unexamined Publication No. 1-3470). The latter method is employed whereby the chilled water the temperature of which is lowered is reheated without stopping a compressor, thus improving precision of the chilled (or hot) water outlet temperature control.
However, since another heat exchanger is required, the overall device must be large-scaled, thus increasing the cost considerably.
Also, the following control method is available in a refrigerating apparatus integrating a compressor with a capacity control unit having a plurality of steps.
The value is read of a temperature sensor only for sensing either chilled (or hot) water outlet or inlet temperature, and when such a value reaches a predetermined temperature on a temperature controller, a signal for decreasing the capacity of the refrigerating apparatus is transmitted. In this method, when the load fluctuates to increase sharply, the capacity of the refrigerating apparatus cannot be increased in one step unless the chilled (or hot) water inlet or outlet temperature rises by a predetermined range of temperature from the foregoing predetermined temperature (differential). Hence, only a rough control can be made of the chilled (or hot) water outlet temperature so as to lower the temperature by a considerable degree with respect to the fluctuation of a load.In the case of controlling the chilled (or hot) water inlet temperature, the greater the number of capacity control stages of the compressor, the more the change in the chilled (or hot) water outlet temperature; on the other hand, in the case of controlling the chilled (or hot) water outlet temperature, the greater the number of capacity control stages of the compressor, the lower the chilled (or hot) water outlet temperature approaching an excessive degree.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a temperature controller in which a readout value from sensors for sensing the chilled (or hot) water inlet and outlet temperatures, respectively, of a refrigerating apparatus is compared with the value which is set on the temperature controller; as a result, when the chilled (or hot) water outlet temperature exceeds a predetermined range of temperature, the capacity of the compressor of the refrigerating apparatus is increased or decreased; and when the compressor is stopped, the compressor is restarted when the readout value from the temperature sensor for sensing the chilled (or hot) water inlet temperature of the refrigerating apparatus exceeds a predetermined range of temperature, thereby maintaining the chilled (or hot) water outlet temperature of the refrigerating apparatus within a predetermined range.
In order to achieve the above object, the present invention provides a temperature controller for a refrigerating apparatus forming a refrigerating cycle by serially connecting a compressor with a capacity control unit, a condenser, an evaporator and an expansion valve to each other via piping, thereby cooling or heating water; the controller comprising: a temperature sensor for sensing water outlet temperature of the refrigerating apparatus and another temperature sensor for sensing water inlet temperature of the refrigerating apparatus; a setting temperature comparison operational unit for setting the upper limit, the lower limit and the stop temperature set value of the water outlet temperature, the seting temperature comparison operational unit for determining setting temperature zones by dividing them into an upper limit or greater zone, a neutral zone between the upper and lower limits, a lower limit or less zone between the lower limit and the stop temperature set value, and the stop temperature set value or less zone; and a restarting comparison operational unit for reading a signal from the water inlet temperature sensor panda signal from the set temperature comparison operational unit after the compressor is stopped, thereby determining whether or not the compressor is restarted.
In one aspect of the present invention, in order to use the temperature controller for switching between chilled and hot water when chilled and hot water can be made in the refrigerating apparatus, the present invention also provides a temperature controller for a refrigerating unit comprising: a water outlet temperature read unit arranged between the water outlet temperature sensor and the setting temperature comparison operational unit for reading a signal from the water outlet temperature sensor; a water inlet temperature read unit arranged between the water inlet temperature sensor and the restarting comparison operational unit for reading a signal from the water inlet temperature sensor; and a setting value switching unit for switching between chilled and hot water connected to both read units.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a control block diagram of one embodiment according to the present invention; Fig. 2 is a time chart showing the change in the temperature of water in the embodiment and; Fig. 3 is a schematic view of a refrigerating apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in Figs. 1, 2 and 3. A refrigerating apparatus 20 forms a refrigerating cycle in which a compressor with a capacity control unit, a condenser, an evaporator and an expansion valve are serially connected to each other via piping. The refrigerating apparatus 20 cools or heats water and feeds such water to an object to be cooled such as a fan coil, an air handling unit, or the like. A temperature controller generally denoted by the reference numeral 3 controls the temperature of the chilled or hot water which is fed from the refrigerating apparatus 20 to the object to be cooled. The temperature controller 3 includes a temperature sensor 1 attached to the piping 14 within the refrigerating unit 20 for sensing the chilled (or hot) water outlet temperature, a chilled (or hot) water outlet temperature read unit 4 for reading the value of resistance from the temperature sensor 1, a setting temperature comparison operational unit 5 for setting the chilled (or hot) water outlet temperature, a temperature sensor 2 provided in the piping 15 within the refrigerating unit 20 for sensing the chilled (or hot) water inlet temperature, the chilled (or hot) water inlet temperature read unit 6 for reading the value of resistance from the temperature sensor 2, a restarting comparison operational unit 7 for adding the setting temperature to the chilled (or hot) water inlet temperature when the compressor is stopped, and a setting value switching unit 13 for switching between the temperature sensors 1 and 2 depending on whether chilled or hot water, is fed to the object to be cooled. The temperature sensors 1 and 2 are usually formed of thermistors the values of resistance of which vary according to the sensed ambient temperature and are continuously read into the chilled (or hot) water outlet temperature read unit 4 and the chilled (or hot) water inlet temperature read unit 6, respectively.The setting temperature comparison operational unit 5 is capable of setting the lower limit of the chilled (or hot) water outlet temperature; the upper limit, the temperature of which can be set variably at a higher temperature than the lower limit; and the stop temperature set value so as to set and store the upper limit or greater zone 8, a neutral zone 9 between the upper and lower limits, the lower limit or less zone 10 between the lower limit and the stop temperature set value, and the stop temperature set value zone 11. The restarting comparison operational unit 7 is connected to the chilled (or hot) water inlet temperature read unit 6 and the setting temperature comparison operational unit 5 so as to transmit signals between them. The setting value switching unit 13 is connected to the temperature sensors 1 and 2.
The operation will now be described. The value read into the chilled (or hot) water outlet temperature read unit 4 is comparison-operated in the setting temperature comparison operational unit 5. If the value falls within the neutral zone 9, the temperature controller 3 does not transmit a signal for increasing or decreasing the capacity of the compressor in the refrigerating apparatus 20, thus maintaining the operation of the refrigerating apparatus 20 without changing the capacity of the compressor.If the value read into the chilled (or hot) water outlet temperature read unit 4 falls within the upper limit or greater zone 8 in the setting temperature comparison operational unit 5, the temperature controller 3 transmits a signal for a one-step capacity increase, thus controlling the refrigerating apparatus 20 so that the chilled (or hot) water outlet temperature of the refrigerating apparatus 20 falls within the neutral zone 9. If the value read into the chilled (or hot) water outlet temperature falls within the lower limit or less, zone 10 in the setting temperature comparison operational unit 5, the temperature controller 3 transmits a signal for one step capacity decrease (for example, 75% capacity), thus controlling the refrigerating apparatus 20 so that the chilled (or hot) water outlet temperature falls within the neutral zone 9.
Fig. 2 shows the relationship between the chilled (or hot) water inlet and outlet temperatures and transmitted signals with reference to a specific load when the refrigerating apparatus 20 is used for cooling.
Referring to the chart, when the value read into the chilled water outlet temperature read unit 4 falls within the neutral zone 9, no signal is transmitted, and consequently, the compressor is operated without changing its capacity. When the value falls out of the neutral zone 9, a signal for a one-step capacity increase or decrease is transmitted, and thus, the compressor is controlled and operated so that the chilled water outlet temperature falls within the neutral zone 9. When the compressor is operated with the minimum capacity (for example, 25% capacity) and a load is further decreased to such a degree that the chilled water outlet temperature falls out of the neutral zone 9, a signal for a one-step capacity decrease can no longer be transmitted.
Therefore, the setting temperature comparison operational unit 5 comparison-operates the value read into the chilled water outlet temperature so as to transmit a compressor stop signal when the value reaches the stop temperature set value zone 11. When the compressor stops, the chilled water inlet and outlet temperatures in the refrigerating apparatus 20 fluctuate as shown in the compressor stop signal sector of Fig. 2. When the compressor stops, the chilled water outlet temperature of the refrigerating apparatus 20 Increases sharply.
Therefore, when the value read into the chilled water inlet temperature read unit 6 from the temperature sensor 2 for sensing the chilled water inlet temperature increases by a predetermined temperature, a compressor restarting signal is transmitted from the restarting comparison operational unit 7 so as to control and operate the compressor so that the chilled water outlet temperature of the refrigerating apparatus 20 is returned to the neutral zone 9.In order to achieve this operation, when the compressor stop signal is transmitted to the refrigerating apparatus 20 as stated above, the setting temperature comparison operational unit 5 also transmits a stop signal to the restarting comparison operational unit 7 which adds a predetermined compressor restarting temperature range to the chilled water inlet temperature value read into the chilled water inlet temperature read unit 6 when the compressor stops, thereby obtaining a setting temperature summing value 12.
When the chilled water inlet temperature increases due to the load fluctuation and reaches the setting temperature summing value 12, the restarting comparison operational unit 7 transmits a signal of restarting the compressor.
Hence, the chilled water outlet temperature of the refrigerating apparatus 20 can be maintained within the predetermined range as shown in Fig. 2 by sensing and controlling the chilled water inlet and outlet temperatures of the refrigerating apparatus 20.
When the refrigerating apparatus 20 is used for heating, the setting value switching unit 13 is switched to the hot water side and the temperature controller 3 to the hot water control side.
As will be clearly understood from the foregoing description, the present invention offers the following advantages.
The refrigerating apparatus can be downsized without requiring a continuous controller when a continuously controlled compressor is utilized and without using a complementary heat exchanger. Also, the fluctuation of the chilled (or hot) water outlet temperature of the refrigerating apparatus which incorporates a compressor including a capacity control unit having a plurality of steps can be maintained within a predetermined range of temperature, thus obtaining a stabilized water temperature.

Claims (3)

WHAT IS CLAIMED IS:
1. A temperature controller for a refrigerating apparatus forming a refrigerating cycle by connecting a compressor with a capacity control unit, a condenser, an evaporator and an expansion valve td each other via piping, thereby cooling or heating water; said controller comprising: a temperature sensor for sensing water outlet temperature of said refrigerating apparatus and another temperature sensor for sensing the water inlet temperature of said refrigerating apparatus;; a setting temperature comparison operational unit for setting the upper limit, the lower limit and the stop temperature set value of said water outlet temperature, said setting temperature comparison operational unit for determining setting temperature zones by dividing them into an upper limit or greater zone, a neutral zone between said upper and lower limits, a lower limit or less zone between said lower limit and said stop temperature set value, and said stop temperature set value or less zone; and a restarting comparison operational unit for reading a signal from said water inlet temperature sensor and a signal from said set temperature comparison operational unit after said compressor is stopped, thereby determining whether or not said compressor is restarted.
2. A temperature controller for a refrigerating unit according to Claim 1, further comprising: a water outlet temperature read unit arranged between said water outlet temperature sensor and said setting temperature comparison operational unit for reading a signal from said water outlet temperature sensor; a water inlet temperature read unit arranged between said water inlet temperature sensor and said restarting comparison operational unit for reading a signal from said water inlet temperature sensor; and a setting value switching unit for switching between chilled and hot water connected to both said read units.
3. A temperature controller substantially as herein described with reference to and as shown in the accompanying drawings.
GB9315007A 1992-07-23 1993-07-20 Refrigerating Apparatus Expired - Fee Related GB2269684B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4196744A JP2708053B2 (en) 1992-07-23 1992-07-23 Refrigerator temperature controller

Publications (3)

Publication Number Publication Date
GB9315007D0 GB9315007D0 (en) 1993-09-01
GB2269684A true GB2269684A (en) 1994-02-16
GB2269684B GB2269684B (en) 1996-05-22

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GB9315007A Expired - Fee Related GB2269684B (en) 1992-07-23 1993-07-20 Refrigerating Apparatus

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JP (1) JP2708053B2 (en)
GB (1) GB2269684B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2309552A (en) * 1996-01-25 1997-07-30 Rwl Consultants Ltd Fail-safe monitoring system
EP2012068A1 (en) * 2007-06-04 2009-01-07 RHOSS S.p.A. Method for regulating the delivery temperature of a service fluid in output from a refrigerating machine
EP2075515A1 (en) * 2006-10-20 2009-07-01 Mitsubishi Heavy Industries, Ltd. Heat source device, heat source system, and method of controlling heat source device
US8157538B2 (en) 2007-07-23 2012-04-17 Emerson Climate Technologies, Inc. Capacity modulation system for compressor and method
US8308455B2 (en) 2009-01-27 2012-11-13 Emerson Climate Technologies, Inc. Unloader system and method for a compressor
USRE44636E1 (en) 1997-09-29 2013-12-10 Emerson Climate Technologies, Inc. Compressor capacity modulation
US10378533B2 (en) 2011-12-06 2019-08-13 Bitzer Us, Inc. Control for compressor unloading system
EP4155622A1 (en) * 2021-09-23 2023-03-29 Carel Industries S.p.A. Regulation method and regulation apparatus of a refrigeration plant and respective refrigeration plant including said apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014030083A2 (en) * 2012-08-20 2014-02-27 Agile 8 Consulting Limited A system and method for improving efficiency of a refrigerant based system
JP6264532B2 (en) * 2013-11-01 2018-01-24 三浦工業株式会社 Food machine with vacuum cooling function

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2202968A (en) * 1987-01-29 1988-10-05 Michael Charles Nash Heat exchanger control

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5934257B2 (en) * 1979-07-06 1984-08-21 三菱電機株式会社 water cooling device
JPS56164477U (en) * 1980-05-09 1981-12-05

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2202968A (en) * 1987-01-29 1988-10-05 Michael Charles Nash Heat exchanger control

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2309552A (en) * 1996-01-25 1997-07-30 Rwl Consultants Ltd Fail-safe monitoring system
GB2309552B (en) * 1996-01-25 2000-01-19 Rwl Consultants Ltd Failsafe system monitoring
USRE44636E1 (en) 1997-09-29 2013-12-10 Emerson Climate Technologies, Inc. Compressor capacity modulation
EP2075515A1 (en) * 2006-10-20 2009-07-01 Mitsubishi Heavy Industries, Ltd. Heat source device, heat source system, and method of controlling heat source device
EP2075515A4 (en) * 2006-10-20 2013-03-27 Mitsubishi Heavy Ind Ltd Heat source device, heat source system, and method of controlling heat source device
EP2012068A1 (en) * 2007-06-04 2009-01-07 RHOSS S.p.A. Method for regulating the delivery temperature of a service fluid in output from a refrigerating machine
US8157538B2 (en) 2007-07-23 2012-04-17 Emerson Climate Technologies, Inc. Capacity modulation system for compressor and method
US8807961B2 (en) 2007-07-23 2014-08-19 Emerson Climate Technologies, Inc. Capacity modulation system for compressor and method
US8308455B2 (en) 2009-01-27 2012-11-13 Emerson Climate Technologies, Inc. Unloader system and method for a compressor
US10378533B2 (en) 2011-12-06 2019-08-13 Bitzer Us, Inc. Control for compressor unloading system
EP4155622A1 (en) * 2021-09-23 2023-03-29 Carel Industries S.p.A. Regulation method and regulation apparatus of a refrigeration plant and respective refrigeration plant including said apparatus

Also Published As

Publication number Publication date
JPH06101910A (en) 1994-04-12
JP2708053B2 (en) 1998-02-04
GB9315007D0 (en) 1993-09-01
GB2269684B (en) 1996-05-22

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20050720