Abstract:
The present invention concerns a cooling or heating system including at least a compressor, a condenser, an expansion apparatus and a vaporizer. The invention is characterized essentially in that in the condenser or in proximity to an outlet of the condenser and before inlet to the expansion apparatus there is a control apparatus arranged to receive condensate-liquid and an intake to a signal channel, and that there is an arrangement to vaporize condensate liquid in the signal channel. An orifice reduces signal channel flow when this flow enters into the cooling or heating system low-pressure side form the signal channel the amount of liquid that is vaporized in the signal channel affects the expansion apparatus connected to the signal channel and the expansion apparatus opening process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is an U.S. national phase application under 35 U.S.C. §371 based upon co-pending International Application No. PCT/SE2006/000680 filed on Jun. 12, 2006. Additionally, this U.S. national phase application claims the benefit of priority of co-pending International Application No. PCT/SE2006/000680 filed on Jun. 12, 2006, Sweden Application 0600539-1 filed on Mar. 13, 2006, and Sweden Application No. 0501354-5 filed on Jun. 13, 2005. The entire disclosures of the prior applications are incorporated herein by reference. The international application was published on Dec. 21, 2006 under Publication No. WO 2006/135310 A1. 
     TECHNICAL FIELD 
     The present invention concerns a cooling or heating apparatus including at least a compressor, a condenser, an expansion apparatus and a vaporiser. 
     The invention also concerns a method for controlling a cooling or heating apparatus including at least a compressor, a condenser, an expansion apparatus and a vaporiser. 
     The invention will be applied to cooling and heating systems with vaporising/condensing coolants as the working medium. The system according to the invention can be applied to all types of cooling system such as air-conditioning, heat pumps, process and apparatus cooling systems that use a piston compressor, screw compressor, scroll compressor, centrifugal compressor, rotation compressor or some other type of compressor and all types of coolants for heat exchange via vaporization/condensation. 
     State of the Art 
     On the market there are different system for regulating and controlling cooling and heating. However, the systems that are used are often complicated and require a large volume and are thereby needlessly expensive. The size and complexity of the systems also means that the control speed and effectiveness is lower than expected. Some previously known systems that have some of the above mentioned disadvantages will be described briefly below. 
     U.S. Pat. No. 4,566,288 and GB-A-659,051 concern different float systems that either affect a valve directly or affect a valve indirectly via electric impulses and send signals to a valve for condensate outflow. These systems are both complicated and controlled with the help of electric impulses and are thereby not self-actuating, and they are large and voluminous with a valve connected to a float for controlling the whole amount of condensate. 
     U.S. Pat. No. 3,388,558 and EP-A-0,939,880 concern systems with thermostat valves that with the help of electrical heating of the system&#39;s thermal part affect a membrane that on pressure increase opens a valve. Neither are these system self-actuating since the control impulse consists of electric resistances for heating a bulb with an external modulation control signal for heating. 
     U.S. Pat. No. 5,156,017 shows a temperature controlled system that controls the flow with the help of the temperature difference between the exit condensate&#39;s supercooling and the condensation temperature. However, these controls do not make full utilization of the condenser surfaces possible since a supercooling loop is required in order to control the exit condensate. 
     U.S. Pat. No. 3,367,130 concerns a system with a traditional thermostatic expansion valve that controls the difference between the vaporisation temperature and overheated gas after the vaporiser with the help of impulses from a gas filled thermosensitive sensor. The system is controlled via overheating gas after vaporization which means that the control impulse for the expansion valve can affect the temperature difference between the coolant and the heat emitting medium negatively. 
     U.S. Pat. No. 4,267,702 concerns systems with a pressure sensitive valve that entirely or partly turn the liquid supply off depending on the pressure difference between operation and stop. However, the systems do not control condensate outflow depending on uncondensed gas. The control function is thus not affected by condensate quality. 
     There is thus a need of a system that in a simple, smooth and easy way solves the problems with the above mentioned systems. 
     DESCRIPTION OF THE INVENTION 
     A purpose of the present invention is to solve the problem that gas in the condensate causes unnecessary power losses. 
     Another purpose of the invention is to solve the problem of controlling the liquid flow from the condenser so that uncondensed gas does not pass by the condenser control. 
     According to a specific embodiment a purpose of the invention is to solve the problem of recycling supercooling heat without decreasing the condenser&#39;s condensing power. 
     According to a first preferred embodiment a purpose of the invention is to solve the problem of controlling the liquid flow with the help of pressure impulses to already known valve constructions. 
     According to an alternative embodiment a purpose of the invention is to give a solution to the problem of controlling the liquid flow in the cooling system/heat pump system with a float valve for signal flow to an expansion valve. 
     A specific purpose of the invention is to control liquid flow in such a way that the system is self-actuating without needing external, for instance electric, control apparatus. 
     Finally, a purpose of the invention is to solve the problem of providing a vaporiser surface with coolant without needing to overheat suction gas for controlling the flow. 
     Said purposes are achieved with a cooling and heating apparatus as given in the characterising portions of patent claims  1  and  14  and the dependent claims belonging to them. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention will be described in the following in a non-limiting way and for illustrative reasons with reference to the attached figures in which: 
         FIG. 1  shows a control system according to a preferred embodiment according to the present invention, 
         FIG. 2  shows a device for detection of gas bubbles according to the present invention, 
         FIG. 3  shows a heat exchanger according to the present invention, 
         FIG. 4  shows a control system according to an alternative embodiment according to the present invention, and 
         FIG. 5  shows a float apparatus according to the present invention. 
         FIG. 6  shows an alternative placement of a control apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a system for thermal, cooling, or freezing systems. The system consists of channels containing coolant (not shown), a compressor  2 , a condenser  4 , an expansion valve  17 A, a vaporiser  20 , a liquid separator  24 , an oil return apparatus  21 , an accumulator  23  and a device  7 A for detection of the presence of gas bubbles intended to control an expansion valve  17 A. 
     When the expansion valve  17 A opens condensed coolant flows to the system&#39;s low pressure side  19  where the medium expands. Thereafter the medium flows further to a vaporiser  20  where heat uptake to coolants takes place from gas, usually air, or liquid, whereby the coolant liquid vaporises. The gas/liquid mixture is then pressured to a liquid separator  24  where liquid is separated from gas. With the help of gravitation some of the liquid is made to pass through a heat exchanger where oil and coolant liquid are separated, after which oil is returned to the compressor  2  via the accumulator  23  and a suction line  1 . Return of liquid that has not been vaporised takes place from the liquid separator  24  via channel to the vaporiser  20 . The compressor  2  compresses the coolant that is thereafter cooled in the condenser  4  where condensation takes place. In  FIG. 6  an alternative embodiment form is shown where the control apparatus  7 A is placed in the condenser in front of its outlet. 
     In  FIG. 2  a device  7 A is shown according to a preferred embodiment that is provided with a drying filter  22  and inspection glass  25 . As not all the gas condenses on passage through the condenser  4  there can still be gas bubbles left in the coolant. The device  7 A separates the gas that has not condensed directly inside the inspection glass  25  so that the control process with separation of gas bubbles can be seen. During compressor operation gas flows via the signal channel opening  14  through an orifice  8  into a signal channel  6 . The gas then passes a heat exchanger  11  after which the signal channel  6  changes into in a signal channel  10 . An electrical heater can possibly be coupled to the signal channel  10 . The gas gives rise to a pressure change that affects an expansion valve  17 A membrane  12  attached to the signal channel  10 . Pressure changes that affect the membrane  12  in turn affect a mechanism  13 , for instance a piston, whereby the expansion valve opening is controlled. An orifice  18  that on its output side is connected to the cooling system&#39;s low pressure side  37  is also arranged in proximity to said channel  10 . Depending on the gas pressure that the gas flowthrough produces gas flows out through the orifice  18 . This gives the space in front of the membrane  12  a pressurisation that is higher than the reference pressure in the space behind the membrane  12  attached to the low pressure side  37  via a compensation channel  26 . 
     When liquid, that is to say condensate, enters the inlet to the signal channel  14  it must pass the orifice  8 , whereby an expansion occurs and the fluid vaporises because of the pressure reduction that the orifice  8  entails. The liquid gas mixture that is formed in the signal channel  6  after the orifice  8  then vaporises additionally in one of the heat exchanger apparatuses  11 ,  34 . During vaporisation a volume increase occurs and essentially all the liquid changes into gas form. Thereafter the gas is led further in the channel  10  to a pressure sensitive expansion valve  17 A that with the help of a mechanism  13  is made to open  16  whereupon the gas is pressured via the orifice  18  to the cooling/heat pump system&#39;s low pressure side  37 . 
     When gas or gas mixed liquid instead of pure liquid enters the inlet to the signal channel  14  a smaller volume increase occurs than when pure liquid enters according to the above. The pressure in the signal channel  10  is affected thereby which also makes the valve&#39;s mechanism  13  close. If the mechanism  13  closes the flow through the valve  17 A is shut off for the condensate that flows through the condensate channel  9  that comes from the device  7 A. The orifice  8  has a smaller flowthrough capacity than the orifice  18  which means that even a small amount of uncondensed coolant can give the expansion valve  17 A an open impulse. 
     The orifice  18  maintains a higher pressure from the high pressure side relative to the low pressure side in order to make a signal to the expansion valve possible. 
     A channel  36 A is arranged parallel to the expansion valve  17 A. When the valve is closed a signal flow is obtained through the valve so that a faster impulse can occur to the signal channel&#39;s  6  intake  14  after the cooling system is started up. 
     In  FIG. 3  a heat exchanger  11  for vaporization of liquid that flows through the signal channel  6 ,  10  is shown. The channel  6 ,  10  preferably has an outside diameter of about 3 millimeters and is attached to a channel  3 ,  9 , preferably in a loop, containing hot gas or condensate, respectively, in order to achieve as large a heat exchange as possible. 
     In  FIG. 4  a control system according to an alternative embodiment according to the present invention is shown. Instead of device  7 A that is used for detection of the presence of gas bubbles according to the embodiment shown in  FIG. 1 , a float apparatus  7 B shown in  FIG. 5  is used in this embodiment. Via a signal channel  31 , a temperature sensitive sensor  28  and a signal channel  27  the float apparatus  7 B gives control impulses to a thermostatic expansion valve  17 B. 
     For sufficient supply of condensate from the condenser  4  a float  29  is raised  33  and a valve  30  is opened, whereby liquid flows into a signal channel  31 . An orifice  18  situated between the signal channel&#39;s  31  inlet valve  30  and the system low pressure side  37  is adjusted to the valve&#39;s  30  flow capacity relative to the orifice  18  in such a way that a temperature increase occurs in the signal channel  31  and in the sensitive element  28  when the flow of coolant through the valve  30  is strong enough. The orifice  18  is adjusted for a smaller flowthrough than the inlet valve  30  as this valve is fully open. Here the orifice  18  maintains a higher temperature on the high pressure side relative to the low pressure side&#39;s temperature. 
     When the coolant flow through the signal channel  31  exceeds a certain level the orifice  18  cannot pass a sufficient quantity of coolant to allow sufficient vaporization of coolant from the liquid phase to the gas phase to take place in the signal channel  31  for which reason the temperature in this channel  31  increases which leads to the expansion valve&#39;s  17 B being opened. 
     When the inlet valve  30  is not required to be open and thereby does not provide a sufficient liquid supply to the signal channel  31  vaporization occurs in the signal channel  31  that is enough to lower the temperature in said channel  31 . The sensitive element  28  for the thermostatic expansion valve  17 B registers the temperature reduction which entails a reduction in steam pressure in the space over the bellows membrane  12 . This pressure reduction leads to the membrane  12  giving the expansion valve  17 B mechanism  13  an order to close, whereby the flow through the expansion valve  17 B decreases. 
     The system according to  FIG. 4  can also by supplied with a heater or the like in order to vaporize liquid present in the signal channel  31  even if that is not required. 
     The system according to the invention provides a cooling/heating system that is simple and inexpensive and provides fast control. 
     The invention results in a small quantity of condensate from the valve  30  being able to control a much larger quantity of condensate via the expansion valve  17 B. 
     Of course the invention is not limited to the embodiments described above and illustrated in the attached drawings. Modifications are feasible, especially concerning the different parts&#39; nature, or through using comparable techniques, without departing from the protected area given in the patent claims because of them. 
     Reference Symbols 
       1  Suction line gas without liquid admixture. 
       2  Compressor 
       3  Hot gas channel 
       4  Condenser for removal of heat. In contact with air or liquid. 
       5  Condensate channel 
       6  Signal channel after orifice  8  before heating  11 . 
       7 A Device for control of the presence of gas bubbles. 
       7 B Float and float housing with valve. 
       8  Orifice 
       9  Condensate channel 
       10  Signal channel 
       11  Heat exchanger 
       12  Pressure membrane 
       13  Piston affected by a membrane and controlling the expansion valve  17 . 
       14  Intake to signal channel  6 ,  10   
       15  Closing function 
       16  Open function 
       17 A Expansion valve 
       17 B Thermostatic expansion valve 
       18  Orifice 
       19  Expansion channel, low pressure side. 
       20  Vaporiser for heat uptake. 
       21  Oil return from liquid separator with heat for vaporization of coolant. 
       22  Drying filter 
       23  Accumulator 
       24  Liquid separator 
       25  Inspection glass 
       26  Signal channel, compensation channel. 
       27  Signal channel to expansion valve. 
       28  Thermal bulb/sensor 
       29  Float body 
       30  Valve affected by the float  29 . 
       31  Signal channel between the float valve and the orifice  18 . 
       32  Valve closes at low liquid level. 
       33  Valve opens at high liquid level. 
       34  Electric heating 
       35  Heat exchanger for liquid supercooling/heat recovery from condensate. 
       36 A Signal flow past expansion valve. 
       37  Low pressure side