FIELD OF INVENTION
The present invention generally relates to a field of mechanical and automobile engineering and particularly to the field of thermal engineering. The present invention specifically relates to a vehicular air conditioning system with an external variable displacement compressor (EVDC) controlling refrigerant superheat and vehicle cabin cooling load with piston stroke alone and eliminating evaporator-thermal expansion valve control loop.
BACKGROUND OF THE INVENTION
In general, swash/wobble plate compressors are widely used in air conditioning systems for vehicles, and include a piston, a piston driving unit, a cylinder block, and a valve in common. In such a swash/wobble plate compressor, a swash/wobble plate whose inclination angle is varied within a crank chamber rotates as its shaft rotates and a piston reciprocates to perform a compressing operation while the swash/wobble plate is rotating. In this case, a refrigerant in a suction chamber is suctioned into a cylinder and is discharged to an exhaust chamber by reciprocal movement of the piston, in which case the inclination angle of the swash/wobble plate is varied to control the amount of exhausted refrigerant according to a difference between a pressure within the crank chamber and a pressure within the suction chamber. As a result, the swash/wobble plate compressor suctions the refrigerant from the suction chamber and compresses the refrigerant by means of the piston, and the compressed refrigerant is exhausted to the exhaust chamber to repeat a cooling cycle. Then, an exhaust check valve for exhausting the compressed refrigerant at a certain pressure and preventing the exhausted gas from reversely flowing to the compressor is installed in an exhaust opening communicated with the exhaust chamber.
It is well known that EVDC changes the angle of the swash/wobble plate, the piston stroke length and the displacement consequently according to an increase or decrease of the pressure differential between the swash/wobble-plate case and the suction chamber to exactly match the vehicle air conditioning demand. It has the advantages such as smooth continuous compressor operation, more comfortable environment inside the car, no frost formation in the evaporator and improved fuel economy. A further improvement to the AC system is invented wherein the capabilities of EVDC are further exploited. However, the existing and conventional technologies of automotive air conditioning provide an expensive installation mechanism by employing a thermal expansion valve in conjunction with variable displacement compressor and thereby adding cost to the system and resulting in poor

performance under certain operating conditions. The limitations of the prior arts and poor performance of the existing and conventional technologies can be overcome by the technical advancements of the present invention which is described in greater detail in later paragraphs.
SUMMARY OF THE INVENTION
The present invention generally relates to an automotive/vehicular air conditioning system with an external variable displacement compressor (EVDC) controlling refrigerant superheat and vehicle cabin cooling load with piston stroke alone and eliminating evaporator-thermal expansion valve control loop.
In an embodiment of the present invention a system of vehicular air conditioning is disclosed. The system comprising: an electronically-controlled variable displacement compressor (EVDC) disposed alongside of a rotor pulley ( with / without clutch) in order to derive power from an engine of a vehicle, wherein the EVDC comprises a swash/wobble plate that rotates to reciprocate pistons and is configured to receive a superheated vapor of refrigerant from an evaporator and compress said refrigerant by reciprocating motion of piston and varies refrigerant mass flow rate by changing the swash/wobble plate angle in accordance with an electrical signal from an electric control unit (ECU); an actuator coupled to the electronically-controlled variable displacement compressor (EVDC) and operatively controlled by the electronic controlled unit (ECU), wherein the actuator comprises a solenoid operated control valve for changing the angle of a swash/wobble plate of said compressor and hence piston stroke, wherein the EVDC is configured to receive an input signal from the ECU via the solenoid valve in order to reciprocate piston stroke by changing the swash/wobble plate angle; a heat exchanging unit disposed substantially within an air conditioning loop, wherein this unit is configured to receive a compressed flow of refrigerant gas from the EVDC, wherein the compressed refrigerant flow is cooled down to a liquid refrigerant after passing through the condensing coils.
The system further discloses a plurality of cooling fans disposed on a rear side of the heat exchanging unit along the widthwise direction of the vehicle, wherein the plurality of cooling fans is configured to cool down the condensing coils by blowing a heat generated inside the condensing coils due to the flow of the superheated refrigerant; a plurality of desiccant beads disposed vertically downwards along the panel and operatively coupled to the outlet of the heat exchanging unit, wherein the plurality of desiccant beads is configured to receive the

flow of refrigerant from the heat exchanging unit via said outlet and absorb moisture from the refrigerant; an orifice tube longitudinally disposed along the length of the discharge gas pipeline and is operatively coupled to the heat exchanging unit, wherein the orifice tube is configured to receive the refrigerant liquid flow and thereby expands the refrigerant liquid along a cross-section of the tube, wherein the expanded refrigerant liquid is transferred to the evaporator being disposed along the length of the suction gas pipeline and operatively coupled to the orifice tube, wherein the evaporator comprises of a plurality of pipes arranged in a horizontal loop, in order to convert the refrigerant liquid passing through the pipes into a vapor, by absorbing surrounding heat from the vehicle cabin, wherein the refrigerant vapor generated by the evaporator is fed to the EVDC in order to complete a cycle of air conditioning; and the EVDC is configured to receive a superheated vapor of refrigerant from the evaporator, wherein when a temperature and pressure of the superheated refrigerant is equal to a first threshold value, the electronic control unit (ECU) transmits a first signal to the EVDC for the piston stroke to remain constant, wherein when the superheat value is more than the first threshold value and less than a second threshold value, the ECU transmits a second signal to the EVDC to increase the piston stroke and thereby the flow of refrigerant increases to reduce the superheat value equal to the first threshold value, wherein when the superheat value is less than the first threshold value, the ECU transmits a third signal to the EVDC to decrease the piston stroke in order to decrease the flow of refrigerant and thereby superheat value increases and equals to the first threshold value.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings
BRIEF DESCRIPTION OF FIGURES
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Figure 1 illustrates a block diagram of components installed in a vehicular air conditioning system in accordance with an embodiment of the present invention.
Figure 2 illustrates a flow diagram of operations involved in the vehicular air conditioning in accordance with an embodiment of the present invention.
Figure 3 illustrates a schematic block diagram of the vehicular air conditioning system in accordance with an embodiment of the present invention.
Figure 4 illustrates a pressure-enthalpy plot for refrigerant, wherein 1-1' represents the predetermined superheat for the vehicular air conditioning system in accordance with an embodiment of the present invention.
Figure 5 illustrates a flow chart for the control of the vehicular air conditioning system with an EVDC and an orifice tube (OT) in accordance with an embodiment of the present invention.
Figure 6 illustrates a schematic diagram of a complete vehicular air conditioning system along with a control system flow chart of operations and controller hardware around EVDC involved in said system in accordance with an embodiment of the present invention.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein

being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises...a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Figure 1 illustrates a block diagram of components installed in a vehicular air conditioning system in accordance with an embodiment of the present invention. The vehicular air conditioning system of the vehicle herein mainly includes a number of components. An electronically-controlled variable displacement compressor (EVDC) (104) is disposed alongside of a rotor Pulley (with / without clutch) (114) in order to derive a power from an engine (102) of a vehicle. The EVDC (104) comprises a swash/wobble plate (108) that

rotates to reciprocate pistons and is configured to receive superheated vapor of refrigerant from an evaporator (110) and compress said refrigerant by reciprocating motion of piston and varies refrigerant mass flow rate by changing the swash/wobble plate (108) angle in accordance with an electrical signal sent to actuator (DPS) (116) from an electric control unit (ECU) (106). The electronic control unit (106) performs an overall actuation of the system in accordance with a signal received from an engine controller (Engine management system) or a user or a driver of said vehicle.
An actuator (116) is provided and is coupled to the electronically-controlled variable displacement compressor (EVDC) (104) and operatively controlled by the electronic controlled unit (ECU) (106). The actuator (116) mainly includes but not limited to a solenoid operated control valve (118) for changing the angle of a swash/wobble plate (108) of said compressor (104) and hence piston stroke is also changed. The EVDC (104) is configured to receive an input signal from the ECU (106) via the solenoid valve (118) in order to reciprocate piston stroke by changing the swash/wobble plate angle.
A heat exchanging unit (120) is disposed substantially within an AC loop in a direction of said vehicle and is operatively coupled to the electronically-controlled variable displacement compressor (EVDC) (104). The heat exchanging unit (120) comprises a condensing unit (122) or condenser. The heat exchanging unit (120) also includes an inlet and an outlet, wherein the inlet is configured to receive a compressed flow of refrigerant from the EVDC (104) inside the plurality of condensing coils. The compressed refrigerant flow is cooled down to a liquid refrigerant after passing through the condensing coils.
A plurality of cooling fans (124) are disposed on a rear side of the heat exchanging unit (120) along the widthwise direction of the vehicle. The cooling fans (124) are configured to cool down the condensing coils by blowing heat generated inside the condensing coils due to the flow of the superheated refrigerant.
A plurality of desiccant beads (126) is also disposed vertically downwards along the panel and operatively coupled to the outlet of the heat exchanging unit (120). The desiccant beads are configured to receive the flow of refrigerant from the heat exchanging unit (120) via said outlet and absorb moisture from the refrigerant.
An orifice tube (128) is provided and is radially longitudinally disposed along the length of the panel and is operatively coupled to the heat exchanging unit (120) via the plurality of beads (126). The orifice tube (128) is configured to receive the refrigerant fluid flow from the

beads (126) and thereby expands the refrigerant fluid along a cross-section of the tube. The expanded refrigerant fluid is then transferred to the evaporator (110) which is disposed along the length of the panel and is operatively coupled to the orifice tube (128). The evaporator (110) mainly includes a plurality of pipes arranged in a horizontal loop, in order to convert the fluid refrigerant passing through the pipes into a vapor, by absorbing surrounding heat from the vehicle cabin. The refrigerant vapor generated by the evaporator is then fed to the EVDC (104) in order to complete a cycle of air conditioning.
The EVDC (104) is configured to receive a superheated vapor of refrigerant from the evaporator (110). When a temperature and pressure of the superheated refrigerant is equal to a first threshold value, the electronic control unit (ECU) (106) transmits a first signal to the EVDC (104) for the piston stroke to remain constant. When the superheat value is more than the first threshold value and less than a second threshold value, the ECU transmits a second signal to the EVDC (104) to increase the piston stroke and thereby the flow of refrigerant increases to reduce the superheat value equal to the first threshold value. When the superheat value is less than the first threshold value, the ECU (106) transmits a third signal to the EVDC (104) to decrease the piston stroke in order to decrease the flow of refrigerant and thereby superheat value increases and equals to the first threshold value.
The rotor pulley (114) of electronically-controlled variable displacement compressor (EVDC) is further connected engine pulley (130) and configured to allow said compressor (104) to get required mechanical power for its functioning.
Figure 2 illustrates a flow diagram of operations involved in the vehicular air conditioning in accordance with an embodiment of the present invention. The method of operating a vehicular air conditioning mainly includes steps which can be described as follows.
The step (202) of the method states receiving a superheated vapor of refrigerant from an evaporator into an electronically-controlled variable displacement compressor (EVDC) disposed alongside of a rotor in order to drive a power from an engine of a vehicle, wherein the EVDC comprises a swash/wobble plate that rotates to reciprocate pistons. Step (204) describes compressing said refrigerant by reciprocating motion of piston and varies refrigerant mass flow rate by changing the swash/wobble plate angle in accordance with an electrical signal from an electric control unit (ECU), wherein the EVDC is configured to receive a superheated vapor of refrigerant from the evaporator, wherein when a temperature and pressure of the superheated refrigerant is equal to a first threshold value, the electronic

control unit (ECU) transmits a first signal to the EVDC for the piston stroke to remain constant, wherein when the superheat value is more than the first threshold value and less than a second threshold value, the ECU transmits a second signal to the EVDC to increase the piston stroke and thereby the flow of refrigerant increases to reduce the superheat value equal to the first threshold value, wherein when the superheat value is less than the first threshold value, the ECU transmits a third signal to the EVDC to decrease the piston stroke in order to decrease the flow of refrigerant and thereby superheat value increases and equals to the first threshold value.
The step (206) herein describes receiving an input signal from the ECU to the EVDC via the solenoid valve in order to reciprocate piston stroke by changing the swash/wobble plate angle, wherein the solenoid valve is coupled to the electronically-controlled variable displacement compressor (EVDC) and operatively controlled by the electronic controlled unit (ECU), wherein the actuator comprises a solenoid operated control valve for changing the angle of a wobble plate of said compressor and hence piston stroke. The step (208) states cooling down, the compressed superheated vapor from the EVDC, to a liquid refrigerant by a heat exchanging unit disposed substantially within an instrument panel in a widthwise direction of a vehicle and is operatively coupled to the electronically-controlled variable displacement compressor (EVDC), wherein the heat exchanging unit comprises a condensing unit having a plurality of condensing coils disposed horizontally and vertically in a mesh, wherein the heat exchanging unit comprises an inlet and an outlet, wherein the inlet is configured to receive a compressed flow of refrigerant from the EVDC inside the plurality of condensing coils.
The step (210) of the method involves blowing a heat generated inside the condensing coils due to the flow of the superheated refrigerant a plurality of cooling fans disposed on a rear side of the heat exchanging unit along the widthwise direction of the vehicle, wherein the plurality of cooling fans is configured to cool down the condensing coils. Step (212) states dehydrating the liquid refrigerant by physical adsorption in order to reduce humidity in a plurality of desiccant beads disposed vertically downwards along the panel and operatively coupled to the outlet of the heat exchanging unit, wherein the plurality of beads is configured to receive the flow of refrigerant from the heat exchanging unit via said outlet and absorb moisture from the refrigerant.

The step (214) states expanding the liquid refrigerant along a cross-section of an orifice tube radially disposed along the length of the panel and is operatively coupled to the heat exchanging unit via the beads, wherein the orifice tube is configured to receive the refrigerant fluid flow from the beads. The step (216) involves transferring the expanded refrigerant fluid to the evaporator being disposed along the length of the panel and operatively coupled to the orifice tube, wherein the evaporator comprises of a plurality of pipes arranged in a horizontal loop, in order to convert the fluid refrigerant passing through the pipes into a vapor, by absorbing surrounding heat from the vehicle cabin, wherein the refrigerant vapor generated by the evaporator is fed to the EVDC in order to complete a cycle of air conditioning.
Figure 3 illustrates a schematic block diagram of the vehicular air conditioning system in accordance with an embodiment of the present invention. The system includes an external variable displacement compressor (304) connected with a rotor pulley (302), the EVDC draws a refrigerant flow in a compressed form with high pressure and temperature towards a condenser (306) which is considered as a heat exchanging unit. The refrigerant can be any common refrigerants employed in refrigeration and air conditioning system such as R-134a, R407c, HF01234yf and the like. A swash/wobble plate is connected to the EVDC which rotates with the reciprocation of the piston stroke. An electronic control unit (ECU) (not shown) is connected to the system such that said electronic control unit dictates the volumetric capacity of the EVDC in accordance with the change in the angle of said swash/wobble plate in response to the piston reciprocation. The ECU further decides the transmission of refrigerant gas or simply the function of EVDC by detecting a temperature of surrounding (inside the vehicle cabin).
The refrigerant gas in the compressed form is transferred to the condenser (306) in line with the EVDC (304). The condenser (306) is a horizontal and vertical mesh of small heat exchanging pipes. The condenser (306) is disposed in a front line of vehicle along the windward direction and at least one fan (308) is installed behind said condenser (306). The condenser (306) receives said compressed refrigerant flow/gas from the EVDC (304) and starts condensing said compressed flow by absorbing heat from the compressed gas and converts it into a liquid refrigerant. The cooling fan (308) rotate and suction air from the surrounding towards said mesh pipes of condenser in order to enhance the conversion of refrigerant gas into refrigerant liquid.

The fluid from the condenser (306) is then transferred to an orifice tube (314) through a number of desiccant beads (312). The desiccant (312) receives the flow and dehydrates the refrigerant by physical adsorption in order to reduce moisture of the refrigerant. The orifice tube (314) is a tube with a length and a cross-section and expands the flow/refrigerant received from the condenser (306) and transfers said expanded fluid flow of refrigerant towards an evaporator (316). The evaporator (316) is disposed within an air conditioning module of the system. The evaporator (316) receives heat from the module and transmits it to the refrigerant fluid received from the orifice tube (314) in order to convert said expanded refrigerant fluid into steam or vapor state. A thermistor (318) is coupled with the evaporator (316) and is having a negative temperature coefficient. The resistance of the thermistor (318) decreases with the increase in temperature of refrigerant heated in the evaporator (316). The thermistor (318) is coupled to the electronic control unit and transmits a signal to the ECU when the temperature of the cabin increases from a first threshold value to a second threshold value. The heated refrigerant is then transferred back to the EVDC (304) when the ECU transmits a signal to the EVDC to compress said heated fluid in the cycle received from the evaporator (316). The simple calculation is that the Evaporator out pressure/temperature are measured and the superheat is calculated from the refrigerant properties equations which are readily available in the form of equations from the refrigerant manufacturers. Based on the superheat calculated, it is determined whether the flow needs to be increased or decreased or kept constant.
Figure 4 illustrates a pressure-enthalpy plot for refrigerant, wherein 1-1' represents the predetermined superheat for the vehicular air conditioning system in accordance with an embodiment of the present invention. As shown in Figure 9 the state of the refrigerant leaving the evaporator is marked by point 1. The value of the superheat is defined as the temperature difference above the point at which refrigerant liquid changes to vapor.
Saturation temperature (Tl') = Temperature at which refrigerant in liquid form changes to vapor at a given pressure (Ps)
Actual temperature (Tl) = Temperature of refrigerant at the evaporator outlet
Superheat = Actual temperature - Saturation temperature = Tl - Tl'
Let us take an example. If the superheat is calculated as 15°C, it indicates that the flow is too low and an increase in stroke is required. When the stroke increases, the flow increases and hence the superheat reduces. Let's say it goes to 10°C. The EVDC indicates that the flow

needs to be further increased and so the instruction is to further increase the stroke. When the superheat reaches the final number, which is predetermined as the optimal number, the stroke remains constant. This happens at all conditions, so the appropriate time delays are applied to make the system operate stably.
Inversely, if there is some liquid at the exit of the evaporator, the measured superheat will be 0°C. In this case, the stroke is reduced to allow for some superheat. It should be a change large enough. Usually, it will be a large change if the ambient temperature which is available to us on the automobile's communication network like CAN/LAN/Flexiray or could be a hard-wired signal. Incidentally, the amount of liquid that comes to the evaporator is not very high by volume because of its higher density (densities of saturated liquid and saturated vapor R134a at 0.3 MPa pressure are 1292.49 kg/m3 and 14.77 kg/m3, respectively). This amount of momentary liquid is not detrimental to the compressor and is quickly remedied. There is also a look up table for ambient temperature and expected stroke. It might be that at an ambient temperature of 20°C, the starting stroke is only 30% and so on. Additionally, the dehydrating function of the A/D and R/D is accommodated by desiccant beads that are installed in the liquid line which comes out of the condenser as a sub-cooled liquid.
Figure 5 illustrates a flow chart for the control of the vehicular air conditioning system with an EVDC and an orifice tube (OT) in accordance with an embodiment of the present invention. The presented AC system with EVDC and Orifice Tube (neither incorporating Receiver nor Accumulator) will be controlled as per the flowchart to meet the various AC requirements such as: varying cooling load; and prevent liquid slugging into the compressor.
The above two requirements are achieved by monitoring the temperature and pressure of the refrigerant leaving the evaporator and integrating a control logic to work in accordance with the electronic control valve logic.
The flowchart states a specific amount of superheat refrigerant is received to the compressor (EVDC). Now, the superheat value is calculated by the controller (ECU) and if the value is equal to an optimum superheat, then there is no change in stroke of piston and hence EVDC. However, if the value is not equal to said optimum then it might be more than optimum and if yes, then the control valve is transmitted a signal to increase the stroke and if said value is not more than optimum then it might be less than said optimum value then the control valve duty cycle is to decrease the stroke, in order to maintain said balance and a displacement signal is

transmitted. Furthermore, when the output signal of displacement towards the EVDC is received there is a change in stroke.
Figure 6 illustrates a schematic diagram of a complete vehicular air conditioning system along with a control system flow chart of operations involved in said system in accordance with an embodiment of the present invention. The control flow chart states that a superheat value is set by a control unit and the temperature of the refrigerant at compressor is calculated. The method is stated as; measure "T" at VDC suction line, then compute "P" using gas equation or measure "P" at suction pipe before VDC; then obtain "Ts" using said "P" (from thermodynamic tables of refrigerant or from state equations); and then compute actual superheat Sha: T-Ts. Now when Sha is greater than SHs, the VDC capacity is increased by increasing supply current/PWM duty cycle; and when Sha is less than SHs the VDC capacity is decreased by decreasing supply current/PWM duty cycle.
The automotive air conditioning system is disclosed herein and displays components such as condenser, compressor, evaporator and controller. A control valve is provided at the compressor inlet to regulate the flow of refrigerant towards the compressor. The control valve is connected to the controller which transmits signal to control said flow. The fluid flow which is supposed to be 100% saturated vapor is transferred from the evaporated to the compressor. The compressor performs function by compressing said flow into a high pressure and temperature refrigerant gas and transmits said compressed gas towards the condenser. The superheated vapor from the compressor is fed to the condenser which transforms the said flow into a subcooled liquid. This subcooled liquid is then transferred to an orifice tube which expands said liquid and feeds said flow back to the evaporator. The controller dictates the flow of fluid from the evaporator towards the compressor by measuring the temperature and pressure of the saturated vapor from the evaporator by an equation
p = PRT M P^TS
SHa = T-Ts
Wherein, P is the pressure of saturated vapor, T is optimum temperature and Ts is the saturated temperature of vapor.
From figure 9, at point Pd which is the VDC outlet, Pd and capacity is controlled by Direct Pressure Sensing DPS valve, such that higher Pd trigger higher mass flow across orifice tube

during high heat loads and at point Ps which is VDC inlet, there is an ideal case of no pressure loss for superheat calculation.
Ps at compressor inlet is influenced by several factors and they have been considered in proper estimation of superheat for VDC capacity control. The factors are as; compressor creating a suction effect during its running; pressure losses due to in pipe length after evaporator; oil -refrigerant gas interaction in this pipe; and heat pickup or Internal Heat Exchanger (IHX) application.
The present invention further states that the system includes an air conditioning unit disposed substantially in an inside middle portion of the instrument panel in the widthwise direction of the vehicle; an air blowing unit having a casing, the air blowing unit being disposed to a front-passenger's side of the air conditioning unit; and an intermediate duct for conducting an air from the air blowing unit to the air conditioning unit.
The system further comprises a control valve disposed over the electronically-controlled variable displacement compressor (EVDC), wherein the control valve comprises an actuator or a solenoid valve configured to receive input commands/signals from the electronic control unit (ECU) to control internal bleed aperture of refrigerant flow from discharge to crankcase chamber due to which crankcase pressure changes.
The control valve further comprises a sub valve element configured to open and close a sub valve provided in a refrigerant passage communicating between a crankcase chamber communication port and a discharge chamber communicating part of the EVDC.
The superheat of the refrigerant flow is equal to a difference of actual temperature and a saturation temperature, wherein the actual temperature is a temperature of the refrigerant at the evaporator outlet and the saturation temperature is a temperature at which the refrigerant changes from liquid form to a vapor form at a fixed pressure inside the electronically-controlled variable displacement compressor (EVDC).
The present invention further states in reference to figure 8 that the system that has an EVDC which is an electronically-controlled variable displacement compressor. In some of the literature it may be called an externally-controlled variable displacement compressor. The difference between this and the IVDC (internally-controlled variable displacement compressor) is that the control valve that allows the compressor to change its stroke is a pneumatic device that reacts to changes in pressure. The program that controls this device is

shown in the flowchart that follows. This program is a closed-loop feedback type of algorithm that is described later. As is evident in Figure 3, the Accumulator/Dehydrator (A/D) as well as the Receiver/Dehydrator is eliminated. The Orifice tube controls the gross mass flow but is not a very good fine controller of flow. So, under some circumstances, there is too much flow in the system resulting in liquid exiting the evaporator and entering the compressor. This is very bad for the compressor because the liquid causes what is referred to as "slugging". This can result in loud noises as the compressor tries to compress the liquid because it is a gas compression device. The other problem is that liquid tends to degrease the insides. The refrigerant liquid is an excellent degreaser and has been used historically to also clean electronic components. The "cleaning" of the inside of the compressor can cause the compressor to seize as the sliding components lose lubrication.
The present invention is about complete elimination of TXV from AC system along with other peripheral components that add to the costs. This requires adding the evaporator-TXV control loop responsibility to EVDC in the form of a designed control strategy implemented by Electronic Control Unit (ECU). The art in use today is the Evaporator-TXV control loop system being self-regulated to balance the heat load, achieve cooling requirements and yet be stable (prevent excess liquid refrigerant entrainment to EVDC). The orifice tube cannot regulate the circulating mass of refrigerant, but the orifice tube along with an EVDC in disclosed invention is utilizing the capabilities of EVDC to its fullest and simplifying the AC system integration and control. The present invention is about controlling the refrigerant superheat and hence stability of evaporator and TXV control loop by controlling the EVDC piston stroke using an actuator controlled by an Electronic Control Unit (ECU). This extended EVDC behavior led to complete elimination of the following components in a conventional AC system namely: a) the TXV as a metering device to prevent liquid entering EVDC; b) the receiver module used with condenser to store excess refrigerant liquid; c) the accumulator and Dryer used after evaporator to contain excess refrigerant liquid thereby preventing the same to enter the EVDC.
The present invention facilitates detecting a physical variable indicating an operating condition of the air-conditioner and refrigerant state inside evaporator; monitoring controlled variable of the AC system (e.g. cabin temperature) to understand the cooling requirements and hence EVDC piston stroke requirement; determining whether or not the operating condition of the AC system is stable on the basis of said detected physical variable; and using

solenoid operated control valve for changing the angle of the swash/wobble plate of said compressor and hence piston stroke.
The method for changing the piston stroke using measured sensor values inside the vehicle and AC system and formulating an enhanced control strategy is developed for an ECU. The sensitivity analysis of the said change on AAC system without thermal expansion valve was done in present invention to establish dual role of EVDC in controlling superheat as well as matching vehicle cooling needs.
The method and systems described herein facilitates elimination of TXV which conventionally control refrigerant mass flow in AC loop based on vehicle heat load requirement at any point of time. Further, the capacity or refrigerant mass flow needed in AC loop is being controlled by EVDC's solenoid valve which in turn is regulated by the ECU. The method and systems described herein provides a better control of the operations and thereby eliminate the need to receiver that is conventionally used in automotive AC system. Furthermore, due to elimination of TXV, the operating control of the air conditioning system is under a single master which is a Solenoid valve with ECU. On one hand the elimination of TXV substantially reduce product cost, the method and system disclosed herein ensures soft start and shut down procedures to monitor EVDC capacity change which is highly efficient and easily controllable.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

We Claim:
1. A vehicular air conditioning system comprising:
an electronically-controlled variable displacement compressor (EVDC) (104) disposed alongside of a rotor pulley (114) in order to drive a power from an engine (102) of a vehicle, wherein the EVDC (104) comprises a swash/wobble plate (108) that rotates to reciprocate pistons and is configured to receive a superheated vapor of refrigerant from an evaporator (110) and compress said refrigerant by reciprocating motion of piston and varies refrigerant mass flow rate by changing the swash/wobble plate (108) angle in accordance with an electrical signal from an electric control unit (ECU) (106);
an actuator (116) coupled to the electronically-controlled variable displacement compressor (EVDC) (104) and operatively controlled by the electronic controlled unit (ECU) (106), wherein the actuator (116) comprises a solenoid operated control valve (118) for changing the angle of a swash/wobble plate (108) of said compressor (104) and hence piston stroke, wherein the EVDC (104) is configured to receive an input signal from the ECU (106) via the solenoid valve (118) in order to reciprocate piston stroke by changing the swash/wobble plate angle;
a heat exchanging unit (120) disposed substantially within an instrument panel in a widthwise direction of a vehicle and is operatively coupled to the electronically-controlled variable displacement compressor (EVDC) (104), wherein the heat exchanging unit (120) comprises a condensing unit (122) having a plurality of condensing coils disposed horizontally and vertically in a mesh, wherein the heat exchanging unit (120) comprises an inlet and an outlet, wherein the inlet is configured to receive a compressed flow of refrigerant from the EVDC (104) inside the plurality of condensing coils, wherein the compressed refrigerant flow is cooled down to a liquid refrigerant after passing through the condensing coils;
a plurality of cooling fans (124) disposed on a rear side of the heat exchanging unit (120) along the widthwise direction of the vehicle, wherein the plurality of cooling fans (124) is configured to cool down the condensing coils by blowing a heat generated inside the condensing coils due to the flow of the superheated refrigerant;
a plurality of desiccant beads (126) disposed vertically downwards along the panel and operatively coupled to the outlet of the heat exchanging unit (120), wherein the plurality

of desiccant beads is configured to receive the flow of refrigerant from the heat exchanging unit (120) via said outlet and absorb moisture from the refrigerant; and
an orifice tube (128) longitudinally disposed along the length of the panel and is operatively coupled to the heat exchanging unit (120) via the plurality of beads (126), wherein the orifice tube (128) is configured to receive the refrigerant fluid flow from the plurality of beads (126) and thereby expands the refrigerant fluid along a cross-section of the tube, wherein the expanded refrigerant fluid is transferred to the evaporator (110) being disposed along the length of the panel and operatively coupled to the orifice tube, wherein the evaporator (110) comprises of a plurality of pipes arranged in a horizontal loop, in order to convert the fluid refrigerant passing through the pipes into a vapor, by absorbing surrounding heat from the vehicle cabin, wherein the refrigerant vapor generated by the evaporator is fed to the EVDC (104) in order to complete a cycle of air conditioning.
2. The vehicular air conditioning system of claim 1, wherein the EVDC (104) is configured to receive a superheated vapor of refrigerant from the evaporator (110), wherein when a temperature and pressure of the superheated refrigerant is equal to a first threshold value, the electronic control unit (ECU) (106) transmits a first signal to the EVDC (104) for the piston stroke to remain constant, wherein when the superheat value is more than the first threshold value and less than a second threshold value, the ECU transmits a second signal to the EVDC (104) to increase the piston stroke and thereby the flow of refrigerant increases to reduce the superheat value equal to the first threshold value, wherein when the superheat value is less than the first threshold value, the ECU (106) transmits a third signal to the EVDC (104) to decrease the piston stroke in order to decrease the flow of refrigerant and thereby superheat value increases and equals to the first threshold value.
3. The vehicular air conditioning system of claim 1, wherein the system further comprises:
a control valve disposed over the electronically-controlled variable displacement compressor (EVDC), wherein the control valve comprises an actuator or a solenoid valve configured to receive input commands/signals from the electronic control unit (ECU) to control internal bleed aperture of refrigerant flow from discharge to crankcase chamber due to which crankcase pressure changes.

4. A method of operating a vehicular air conditioning, the method comprising steps:
receiving superheated vapor of refrigerant from an evaporator into an electronically-controlled variable displacement compressor (EVDC) disposed alongside of a rotor pulley in order to drive a power from an engine of a vehicle, wherein the EVDC comprises a swash/wobble plate that rotates to reciprocate pistons;
compressing said refrigerant by reciprocating motion of piston and varies refrigerant mass flow rate by changing the swash/wobble plate angle in accordance with an electrical signal from an electric control unit (ECU), wherein the EVDC is configured to receive a superheated vapor of refrigerant from the evaporator, wherein when a temperature and pressure of the superheated refrigerant is equal to a first threshold value, the electronic control unit (ECU) transmits a first signal to the EVDC for the piston stroke to remain constant, wherein when the superheat value is more than the first threshold value and less than a second threshold value, the ECU transmits a second signal to the EVDC to increase the piston stroke and thereby the flow of refrigerant increases to reduce the superheat value equal to the first threshold value, wherein when the superheat value is less than the first threshold value, the ECU transmits a third signal to the EVDC to decrease the piston stroke in order to decrease the flow of refrigerant and thereby superheat value increases and equals to the first threshold value;
receiving an input signal from the ECU to the EVDC via the solenoid valve in order to reciprocate piston stroke by changing the swash/wobble plate angle, wherein the solenoid valve is coupled to the electronically-controlled variable displacement compressor (EVDC) and operatively controlled by the electronic controlled unit (ECU), wherein the actuator comprises a solenoid operated control valve for changing the angle of a swash/wobble plate of said compressor and hence piston stroke;
cooling down, the compressed superheated vapor from the EVDC, to a liquid refrigerant by a heat exchanging unit disposed substantially within an instrument panel in a widthwise direction of a vehicle and is operatively coupled to the electronically-controlled variable displacement compressor (EVDC), wherein the heat exchanging unit comprises a condensing unit having a plurality of condensing coils disposed horizontally and vertically in a mesh, wherein the heat exchanging unit comprises an inlet and an outlet, wherein the inlet

is configured to receive a compressed flow of refrigerant from the EVDC inside the plurality of condensing coils;
blowing a heat generated inside the condensing coils due to the flow of the superheated refrigerant a plurality of cooling fans disposed on a rear side of the heat exchanging unit along the widthwise direction of the vehicle, wherein the plurality of cooling fans is configured to cool down the condensing coils;
dehydrating the liquid refrigerant by physical adsorption in order to reduce moisture in a plurality of desiccant beads disposed vertically downwards along the panel and operatively coupled to the outlet of the heat exchanging unit, wherein the plurality of beads is configured to receive the flow of refrigerant from the heat exchanging unit via said outlet and absorb moisture from the refrigerant;
expanding the liquid refrigerant along a cross-section of an orifice tube radially disposed along the length of the panel and is operatively coupled to the heat exchanging unit via the beads, wherein the orifice tube is configured to receive the refrigerant fluid flow from the beads; and
transferring the expanded refrigerant fluid to the evaporator being disposed along the length of the panel and operatively coupled to the orifice tube, wherein the evaporator comprises of a plurality of pipes arranged in a horizontal loop, in order to convert the fluid refrigerant passing through the pipes into a vapor, by absorbing surrounding heat from the vehicle cabin, wherein the refrigerant vapor generated by the evaporator is fed to the EVDC in order to complete a cycle of air conditioning.