SE542587C2

SE542587C2 - A temperature control system and a vehicle provided with such a system

Info

Publication number: SE542587C2
Application number: SE1851234A
Authority: SE
Inventors: Martin Mohlin; Ola Hall
Original assignee: Scania Cv Ab
Priority date: 2018-10-09
Filing date: 2018-10-09
Publication date: 2020-06-09
Also published as: SE1851234A1

Abstract

A temperature control system, comprising: a first cooling circuit (1) with tubing (2) for conducting a refrigerant, a compressor (3), a condenser (4), a first refrigerant-treating device (5) having a volume V, a first expansion valve 7, and a heat exchanger arrangement 8, and a second cooling circuit (10), comprising tubing (11), a second expansion valve (14), a second refrigerant treating device (15) having a volume Vand provided upstream said second expansion valve (14), and a heat exchanger arrangement (16). The second refrigerant-treating device (15) has a length L and has a larger cross-sectional area Athan the crosssectional area Aof a channel defined by an upstream tubing (11) of the second circuit (10), and has an inlet (18) for inflow of refrigerant located at a level above an outlet (19) for outflow of refrigerant, thereby preventing gas bubbles above a diameter dbfrom reaching the second expansion valve (14), and wherein V<0,5V.

Description

The present invention relates to a temperature control system,comprising: a first cooling circuit in which there is provided, tubingfor conducting a refrigerant, a Compressor configured to pump therefrigerant in a first direction in the first cooling circuit, acondenser, a first refrigerant treating device, defining a chamberhaving a volume V1 and configured to separate water and particlesfrom the refrigerant and to prevent gas bubbles having above apredetermined diameter dm from passing the first refrigeranttreating device in said first direction, a first expansion valve, anda heat exchanger arrangement via which heat is adopted by therefrigerant for the purpose of cooling a component or a mass of airor liquid, and a second cooling circuit, connected in parallel withthe first cooling circuit and comprising: tubing for conducting arefrigerant, said tubing being connected to the tubing of the firstcooling circuit at a first connection point located between thecondenser and the first refrigerant-treating device and at a secondthe heat arrangement of the first cooling circuit, such that at least some of connection point located downstream exchangerthe refrigerant that is pumped through the condenser by theCompressor in said first direction is pumped into the secondcooling circuit, a second expansion valve, a second refrigeranttreating device, defining a chamber having a volume V2 andprovided downstream said first connection point and upstream said second expansion valve, and a heat exchanger arrangement via which heat is adopted by the refrigerant for the purpose of cooling a component or a mass of air or liquid.

The present invention also relates to a vehicle provided with such a temperature control system.

The term “tubing” as applied in this disclosure should be regardedin a wide sense and may include all sorts of structural elementsthat define a channel through which a coolant may flow. A tubingas used in this disclosure may also comprise a plurality ofstructural elements that together define the tubing, said structuralelements not necessarily having the traditional geometric tubularshape of a tube. However, in those applications in which tubes areeconomically and technically favorable, such tubes will be the preferred structural elements that form said tubing.

The heat exchanger arrangements in the first and second circuittypically defines evaporators in which liquid refrigerant from the respective expansion valve is evaporated.

BACKGROUND AND PRIOR ART When designing an AC-system with multiple evaporators (multiplepaths) it must be ensured that both evaporators and expansionvalves always receive refrigerant in liquid state and not in gaseousstate. This is usually achieved by means of a so called drier bottlewhich acts as a buffer for the AC media and contains both gas andliquid. The drier bottle normally has three tasks, namely toseparate particles from the refrigerant, to separate water from the refrigerant and to prevent gas bubbles of a certain size from reaching an expansion valve positioned downstream the drier bottle as seen in the flow direction of the refrigerant.

However, when having two evaporators in two parallel circuitsthere will be a problem in controlling how much refrigerant there isin each individual drier bottle. One can be empty and the other full.lf only one drier bottle is used, that drier bottle will have to belocated upstream a position where the path split, i.e. where thesecond circuit is branched off from the first circuit (in many casesthat will be close to the compressor). This in turn gives two moreproblems. Firstly, it can make installation more difficult since itlimits the positioning possibilities. Secondly, if AC-routing is long,for example if the second circuit has its expansion valve andevaporator located at a substantial distance from the split point(and thus from the drier bottle), control of the media state may belost and re-evaporating of the refrigerant may occur even before it has reached the expansion valve.

SUMMARY OF THE INVENTION lt is an object of the present invention to present a temperaturecontrol system as defined in the preamble of claim 1 and in thebeginning of this disclosure, which temperature control system reduces or even solves the above-mentioned problems of prior art.

The object of the invention is achieved by means of the initiallydefined temperature control system, characterized in that thesecond refrigerant-treating device is a portion of the tubing of thesecond circuit which has a length L and which defines a channel that has a larger cross-sectional area A2 than the cross-sectional area A1 of a channel defined by the tubing of the second circuitupstream said portion, and that has an in|et for inflow of refrigerantinto said portion located at a level above an outlet for outflow ofrefrigerant from said portion, said second refrigerant-treatingbubbles predetermined diameter db2 from passing the second refrigerant device thereby preventing gas having above atreating device and reaching the second expansion valve underpredetermined operation conditions of the temperature control system, and that V2 The second refrigerant-treating device will act as a buffer for thesecond evaporator for minor fluctuations in liquid/gas amounts butis not large enough to disrupt the function of the first refrigerant-treating device. While the first refrigerant-treating device takescare of separation of particles and water from the refrigerant forboth the first and the second circuit, and for preventing gasbubbles over a predetermined size from reaching the firstexpansion valve, the second refrigerant-treating device has as itsmain purpose only to prevent gas-bubbles above a certain size from reaching the second expansion valve.

The fact that the in|et to the second refrigerant-treating device isabove the level of the outlet thereof, as seen in the verticaldirection, will, as a result of the gravitational force, result in slowerflow velocity of gas bubbles above a certain size than the liquidrefrigerant through said device, such that they do not reach theoutlet. They will either condense or be whipped into smallerbubbles by the Preferably, the longitudinal axis of said portion extends with an liquid refrigerant flowing at higher velocity. angle of at least 45°, or even more preferably with an angle of at least 80°, most preferably perpendicularly, in relation to the horizontal plane.

By adapting the length L of said portion of the tubing and the crosssectional area A2 thereof, the preventive effect of the secondrefrigerant-treating device can be adjusted, for example withregard to the design and sensitivity of the second expansion valve.lf bubbles above a certain size reach the expansion valve, thelatter may interpret this as that there is no mass of refrigerantpassing through it, and it will open and close intermittently asbubbles above said size reach the expansion valve. ln accordancewith the teaching of the present invention, by adapting the lengthL and cross section A2 of said portion of the tube, the upper limitof the size of gas bubbles that reach the expansion valve iscontrolled.

The predetermined conditions of the temperature control systemmay include all conditions that may occur under full functionalityof the components present therein, such as maximum and/orminimum output of the compressor and maximum and/or minimumheat exchange between the refrigerant in the respective circuit and components/mass of gas/mass of liquid.

According to one embodiment, V2<0,25V1.

According to one embodiment, the second expansion valve has aspring-supported movable member which is movable a distance dsbetween a maximum open position, in which it opens for maximum passage of refrigerant through the second expansion valve, and a closed position in which it prevents passage of refrigerant through the second expansion valve, and that db2>O,5dS.

According to one embodiment, db2>1,OdS.

According to one embodiment, A2>2-A1. According to yet anembodiment, A2>4-A1. A2 is a mean value for the cross-sectionalarea along the length of said portion. Preferably, along said portion, the cross section is within the range of O,7A2-1,3A2.

According to one embodiment, said channel of said portion has amean diameter D along said portion wherein L>2-D. According to one embodiment L According to one embodiment, said portion is an integrated part ofa tube extending from said first connection point to the secondexpansion valve. Alternatively, said portion is a tube or hoseattached to a tube extending from the said first connection point towards the second expansion valve.

According to one embodiment, said operation conditions include acondition of the system in which there is a maximum refrigerantflow rate through the second circuit within the limits given by thesystem. The operation conditions also include that the amount ofrefrigerant in the temperature control system is above a level defined as the minimum amount of refrigerant in the system.

According to one embodiment, said operation conditions include a condition of the system in which the amount of refrigerant in the first and second circuits is within a predetermined range defined as a nominal operation range.

The object of the invention is also achieved by means of a vehicle,characterized in that it comprises a temperature control system asdefined hereinabove or hereinafter.

According to one embodiment, the vehicle is characterized in thatsaid portion of the tubing of the second cooling circuit has alongitudinal axis and that, when the vehicle stands on a horizontalground, the longitudinal axis of said portion extends with an angleof at least 45° in relation to the horizontal plane, and that the inletis located above the outlet.

According to one embodiment, the vehicle is characterized in thatsaid portion of the tubing of the second cooling circuit haslongitudinal axis and that, when the vehicle stands on a horizontalground, the longitudinal axis of said portion extends with an angleleast 80°, horizontal plane, and that the inlet is located above the outlet. of at preferably perpendicular, in relation to the Further features and advantages of the present invention will be presented in the following detailed description of an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment will be described in detail with reference to annexed drawing, on which: Fig. 1 is a schematic representation of a temperature controlsystem according to the present invention, Fig. 2 is cross-sectional view of a second refrigerant-treatingdevice, and Fig. 3 is a cross-sectional view of an expansion valve.

DETAILED DESCRIPTION OF EMBODIMENTS Fig. 1 is a schematic representation of a temperature controlsystem according to one embodiment of the present invention. Thetemperature control system is, preferably, provided in a vehicle forthe purpose of directly or indirectly cooling components or massesof gas (such as air) or liquid. The temperature control system may be referred to as an AC-system.

The temperature control system comprises a first cooling circuit 1in which there is provided tubing 2 for conducting a refrigerant, acompressor 3 configured to compress and pump the refrigerant ina first direction, indicated with an arrow in fig. 1, in the first coolingcircuit 1. The first circuit 1 further comprises a condenser 4, a firstrefrigerant treating device 5, defining a chamber 6 having a volumeV1 and configured to separate water and particles from therefrigerant and to prevent gas bubbles having a predetermineddiameter db1 from passing the first refrigerant treating device 5 insaid first direction. The first circuit 1 also comprises a firstexpansion valve 7 downstream the first refrigerant-treating device5, an evaporator 8 downstream the expansion valve 7 which formsexchanger arrangement, via which heat is adopted by therefrigerant for the purpose of cooling a component or a mass of air or liquid. There is also provided a one-way valve 9 upstream the expansion valve 7, by means of which the flow through the firstcircuit can be shut off. By way of example, the one-way valve 9 isarranged downstream the first refrigerant-treating device 5.Alternatively, it may be arranged upstream the first refrigerant-treating device 5. Downstream is referred to as downstream as seen from the compressor 3 in said first direction.

The temperature control system also comprises a second coolingcircuit 10, connected in parallel with the first cooling circuit andcomprising tubing 11 for conducting a refrigerant, said tubingbeing connected to the tubing 2 of the first cooling circuit at a firstconnection point 12 located between the condenser 4 and the firstrefrigerant-treating device 5 and at a second connection point 13located downstream the evaporator 8 of the first cooling circuit 1,such that at least some of the refrigerant that is pumped throughthe condenser 4 by the compressor 3 in said first direction ispumped into the second cooling circuit 10. The second circuit 10also comprises a second expansion valve 14, a second refrigeranttreating device 15, defining a chamber having a volume V2 andprovided downstream said first connection point 12 and upstreamsaid second expansion valve 14, and an evaporator 16 that definesa heat exchanger arrangement via which heat is adopted by therefrigerant for the purpose of cooling a component or a mass of airor liquid. There is also provided a one-way valve 17 upstream theexpansion valve 7, by means of which one-way valve 17 the flowthrough the second circuit can be shut off. By way of example, theone-way valve 17 is arranged upstream the second refrigerant-treating device 15. Alternatively, it may be arranged downstream the second refrigerant-treating device 15.

Reference is made to fig. 1 and fig. 2. The second refrigerant-treating device 15 is a portion of the tubing 11 of the second circuit10, which portion has a length L and which defines a channel thathas a larger cross-sectional area A2 than the cross-sectional areaA1 of a channel defined by the tubing 11 of the second circuitupstream said portion 15. The second refrigerant-treating device15 has an inlet 18 for inflow of refrigerant into said portion locatedat a level above an outlet 19 for outflow of refrigerant from saidportion 15. Thereby, said second refrigerant-treating device 15prevents gas bubbles having above a predetermined diameter dbzfrom passing the second refrigerant treating device 15 andreaching the second expansion valve 14 under predeterminedoperation conditions of the temperature control system. Thevolume V2 of the chamber defined by the second refrigerant-treating device 15 is substantially smaller than the volume V1defined by the first refrigerant-treating device 5, since it does notneed to include means for separation of particles and water fromthe refrigerant. That is done by the first refrigerant-treating device.Here, V2 According to one embodiment, V2<0,25V1. ln other words, the increased cross-section area A2 and the lengthL of said portion 15 are adapted such that bubbles of gas presentin the refrigerant having a diameter db which would cause anincreased opening of the second expansion valve 14 upon arrivalof said bubbles at the second expansion valve 14, are preventedfrom passing said portion 15 and reaching said second expansionvalve 14 due to the effect of the gravitational force that will makethem flow slower than the liquid refrigerant through said portion15. 11 Fig. 3 illustrates an example of an expansion valve. The secondexpansion valve 14 may be of a similar design as the expansionvalve shown in fig. 3. Therefore, the expansion valve shown infig.3 has been indicated with reference number 14. The expansionvalve 14 may, of course, be of a more complex type that comprisesmore features than shown in the drawing. Such solutions are,however, also conceived as covered by the scope of protection ofthe present disclosure. The second expansion valve 14 has aspring-supported movable member 20, which is movable adistance ds between a maximum open position, in which it opensfor maximum passage of refrigerant through the second expansionvalve 14, and a closed position in which it prevents passage ofrefrigerant through the second expansion valve 14. lt also has apower dome 21 and a diaphragm 22 as is common for expansionvalves. The length L of said portion 15 and the cross-sectionalarea A2 of the channel defined by said portion are configured suchthat, for the pressures and flows of refrigerant that can beexpected in the second circuit 10, generally all bubbles larger than1,0ds are prevented from passing said portion 15. ln other words,db2>1,OdS. According to an alternative embodiment, by adapting Land A2, all bubbles having a diameter dbz which is more than halfthe distance ds are prevented from passing said portion 15.Accordingly, db2>O,5dS.

The channel defined by said portion 15 has a mean diameter Dalong said portion 15, wherein 2-D mentioned earlier in this disclosure. When the vehicle stands on a 12 horizontal ground, the longitudinal axis of said portion 15 shouldextend with an angle of at least 45° in relation to the horizontal plane, preferably perpendicularly. lt should be added that, of course, the temperature control systemaccording to the present invention may include further componentsand circuits than those that have been disclosed in this disclosure,and that the claimed scope of protection for the present invention also includes such embodiments.

Claims

1. A temperature control system, comprising: -a first cooling circuit (1) in which there is provided, -tubing (2) for conducting a refrigerant, -a compressor (3) configured to pump the refrigerant in a firstdirection in the first cooling circuit (1), -a condenser (4), -a first refrigerant treating device (5), defining a chamber having avolume V1 and configured to separate water and particles from therefrigerant and to prevent gas bubbles having above apredetermined diameter dm from passing the first refrigeranttreating device in said first direction, -a first expansion valve 7, and -a heat exchanger arrangement 8, via which heat is adopted by therefrigerant for the purpose of cooling a component or a mass of airor liquid, -a second cooling circuit (10), connected in parallel with the firstcooling circuit (1) and comprising: -tubing (11) for conducting a refrigerant, said tubing (11) beingconnected to the tubing (2) of the first cooling circuit (1) at a firstconnection point (12) located between the condenser (4) and thefirst refrigerant-treating device (5) and at a second connectionpoint (13) located downstream the heat exchanger arrangement(8) of the first cooling circuit (1), such that at least some of therefrigerant that is pumped through the condenser (4) by thecompressor (3) in said first direction is pumped into the secondcooling circuit (10), -a second expansion valve (14), - a second refrigerant treating device (15), defining a chamberhaving a volume V2 and provided downstream said first connectionpoint (12) and upstream said second expansion valve (14), and-a heat exchanger arrangement (16) via which heat is adopted bythe refrigerant for the purpose of cooling a component or a massof air or liquid, said temperature control system being characterized in that thesecond refrigerant-treating device (15) is a portion of the tubing(11) of the second circuit (10) which has a length L and whichdefines a channel that has a larger cross-sectional area A2 thanthe cross-sectional area A1 of a channel defined by the tubing (11)of the second circuit (10) upstream said portion (15), and that hasan inlet (18) for inflow of refrigerant into said portion (15) locatedat a level above an outlet (19) for outflow of refrigerant from saidportion (15), said second refrigerant-treating device (15) therebypreventing gas bubbles having above a predetermined diameterdbz from passing the second refrigerant treating device (15) andreaching the second expansion valve (14) under predeterminedoperation conditions of the temperature control system, and thatV2

2. A temperature control to claim 1,characterized in that V2<0,25V1. system according

3. A temperature control system according to claim 1 or 2,characterized in that the second expansion valve (14) has aspring-supported movable member (20) which is movable adistance ds between a maximum open position, in which it opensfor maximum passage of refrigerant through the second expansion valve (14), and a closed position in which it prevents passage of refrigerant through the second expansion valve (14), and thatdb2>1,0ds.

4. A characterized in that db2>O,5dS. temperature control system according to claim 3,

5. A temperature control system according to any one of claims1-4, characterized in that the A2>4-A1.

6. A temperature control system according to any one of claims1-5, characterized in that said channel of said portion (15) has a mean diameter D along said portion and that L>2-D.

7. A temperature control system according to any one of claims1-6, characterized in that said portion (15) is an integrated partof a tube extending from said first connection point (12) to the second expansion valve (14).

8. A temperature control system according to any one of claims1-7, characterized in that said operation conditions include acondition of the system in which there is a maximum refrigerant flow rate through the second circuit (10).

9. A temperature control system according to any one of claims1-8, characterized in that said operation conditions include acondition of the system in which the amount of refrigerant in thefirst and second circuits (1, 10) is within a predetermined range defined as a nominal operation range.

10. A vehicle, characterized in that it comprises a temperature control system according to any one of claims 1-9.

11. A vehicle according to claim 10, characterized in that saidportion (15) of the tubing (11) of the second cooling circuit (10)has a longitudinal axis and that, when the vehicle stands on ahorizontal ground, the longitudinal axis of said portion (15) extendswith an angle of at least 45° in relation to the horizontal plane, andthat the inlet (18) is located above the outlet (19).

12. A vehicle according to claim 10, characterized in that saidportion (15) of the tubing (11) of the second cooling circuit (10)has longitudinal axis and that, when the vehicle stands on ahorizontal ground, the longitudinal axis of said portion (15) extendswith an angle of at least 80° in relation to the horizontal plane, andthat the inlet (18) is located above the outlet (19).