Flow rate adjustment valve for refrigeration cycle

A flow rate regulation valve is used for a refrigeration cycle device for air conditioning. The flow rate regulation valve is constituted by: an inlet flow rate control valve connected to the inlet side of an inside evaporator and functioning in the refrigeration cycle device as an expansion valve for depressurizing and expanding a refrigerant flowing into the inside evaporator; and an outlet flow rate adjustment valve connected to the outlet side of the inside evaporator and functioning as an evaporation pressure adjustment valve for adjusting evaporation pressure in the inside evaporator to a predetermined target pressure at which frost is not formed. The flow rate regulation valve is characterized in that, when the opening of one of the inlet flow rate control valve and the outlet flow rate adjustment valve increases, the flow rate regulation valve displaces so that the opening of the other decreases.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2013/062665 filed on Apr. 30, 2013 and published in Japanese as WO 2013/172201 A1 on Nov. 21, 2013. This application is based on and claims the benefit of priority from Japanese Patent Applications No. 2013-083829 filed Apr. 12, 2013 and No. 2012-110820 filed May 14, 2012. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a flow regulating valve which regulates a flow rate of a refrigerant which flows to an evaporator of a refrigeration cycle.

BACKGROUND ART

PLT 1 shows a refrigeration cycle which is provided with a cooling operation mode and a “dehumidifying heating mode” described hereafter and enables switching between them. The cooling operation mode is a mode where an inside evaporator which is arranged at the inside of the compartment is used to cool the air which is blown to the inside of the compartment to cool the passenger compartment. The “dehumidifying heating mode” of this PLT 1 is a refrigerant circuit wherein an inside evaporator, and an outside heat exchanger which exchanges heat of a refrigerant with the outside air are connected in parallel at the downstream side of the inside condenser. Due to this, the outside heat exchanger and inside evaporator are made to function as heat absorbers. The inside evaporator absorbs heat from the fan air for a dehumidifying action. The inside condenser reheats the fan air and vents it to the inside for a heating and dehumidifying action.

In this PLT 1, an embodiment of use of an evaporation pressure regulator 12 at the outlet side of the inside evaporator 2 is shown. In both the cooling operation mode and dehumidifying heating mode, refrigerant flows to the evaporation pressure regulator. As an evaporation pressure regulator (also called “EPR”), a spring type evaporation pressure regulator (as one example, Japanese Patent No. 2781064 etc.) has been used. This holds the evaporation pressure of the refrigerant inside the evaporator at a certain pressure or more to prevent formation of frost of the inside evaporator (freezing of the moisture from dehumidification). That is, if the evaporation pressure of the refrigerant inside the evaporator falls, simultaneously the evaporation temperature falls (on the isobaric line at the two-phase region on a Mollier chart, the temperature is also constant), so frost ends up being formed. Therefore, in the spring type evaporation pressure regulator, the evaporation pressure of the refrigerant in the evaporator is held at a constant pressure or more.

In PLT 1, in both the cooling operation mode and “dehumidifying heating mode”, the evaporation pressure regulator controls the evaporation pressure of the refrigerant in the evaporator to a predetermined setting or more so as to prevent frost. However, in the prior art, a well known spring type evaporation pressure regulator (EPR) was used, so there were the following problems.

(1) The fins or tubes at the air side are cooled by conduction of heat from the inside refrigerant temperature, so when the air which is blown is high in temperature, the temperature difference between the temperature of the fins or tubes and the inside refrigerant temperature becomes large. In a spring type evaporation pressure regulator, the evaporation pressure is set to a constant pressure and control cannot be performed to lower the evaporation pressure (that is, evaporation temperature), so in the summer etc. when the air which is blown is high in temperature, the fins or tubes become high in temperature and the vented air temperature also ends up becoming higher. For this reason, it is not possible to suitably make use of the cooling capacity.

(2) The spring type evaporation pressure regulator uses a valve element (piston) which adjusts the refrigerant flow rate and a coil spring which biases the valve element in the closing direction. If the refrigerant flow rate is large, the opening of the valve element becomes larger. This means compressing the coil spring (opening of valve element and spring pressure are proportional). That is, the evaporation pressure of the refrigerant rises. Conversely, if the refrigerant flow rate is small, the opening of the valve element becomes small and the evaporation pressure also becomes low. For this reason, in order to prevent formation of frost of the evaporator, the setting has to be determined, when refrigerant flow rate is small, i.e., where the evaporation pressure (evaporation temperature) becomes the lowest. By doing this, in the summer season etc. when the refrigerant flow rate is large, the opening of the valve element becomes large and the evaporation pressure (evaporation temperature) also ends up becoming high. For this reason, the vented air temperature also ends up becoming higher, so it is not possible to suitably make use of the cooling capacity. That is, when the flow rate is large, inherently, if changing to a target value of a lower refrigerant temperature, a suitable cooling capacity should be able to be realized, but that is not so.

(3) When detecting the vented air temperature from the evaporator and using control to adjust the amount of discharge refrigerant of the compressor, if there is a spring type evaporation pressure regulator, the vented air temperature no longer falls to the set evaporation pressure (set evaporation temperature) of the evaporation pressure regulator or less. For this reason, even if the cooling load falls, the vented air temperature does not fall, so the speed of the electric compressor and the discharge capacity of the variable discharge compressor do not fall, the power increases more than necessary, and the COP ends up falling. Further, the fan air flow also does not fall and blowing of air continues unnecessarily.

(4) The spring type evaporation pressure regulator closes at a set pressure or less (usually, saturation pressure of HFCl34a at 0° C. of 292.8220 kPa[abs] or less). For this reason, when filling refrigerant in the refrigeration cycle, the inside is evacuated to discharge the air, but if the evaporation pressure regulator closes, there is the problem that a long time is taken for evacuation.

(5) If gas leakage etc. causes a drop in the amount of refrigerant in the refrigeration cycle, the liquid refrigerant in the accumulator disappears, the pressure in the evaporator drops, the opening of the spring type evaporation pressure regulator is reduced, and the compressor inlet pressure also falls. Due to this, there is the problem of a rise in the degree of overheating of the refrigerant which is sucked into the compressor and a rise in the discharge temperature due to an increase in the compression ratio.

(6) In a cycle which switches between cooling and heating, if a dehumidifying operation is not required at the time of heating, sometimes the evaporator inlet is closed by a solenoid valve, expansion valve, etc. to prevent refrigerant from flowing to the evaporator. When the compressor inlet pressure is low, the spring type evaporation pressure regulator automatically closes, so refrigerant pools inside the evaporator and sometimes the amount of refrigerant in the accumulator becomes insufficient. Further, when the air which is blown to the evaporator changes from the outside air to the inside air and the evaporator is heated, the refrigerant at the inside of the evaporator rapidly evaporates and the refrigerant flow rate increases, so there is the problem that fluctuations in vented temperature and fluctuations in compressor power occur.

Furthermore, with the cycle configuration of PLT 1 where different operation modes such as cooling and heating are switched between, pluralities of expansion valves and evaporation pressure regulators have to be used. Not only was there a problem in the increased number of parts and mountability, but also interference occurred between the evaporation pressure regulator and control for adjusting the amount of discharge refrigerant of the compressor.

CITATIONS LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The present invention, in view of the above problem, provides a flow regulating valve for inside evaporator use which functions both as an electric evaporation pressure regulator for frost control use and an expansion valve of a refrigeration cycle.

Solution to Problem

To solve this problem, the invention of claim1provides a flow regulating valve (19) which is used in a refrigeration cycle system for air-conditioning use which has an inside condenser (12), outside heat exchanger (15), and inside evaporator (20), wherein the flow regulating valve (19) comprises an inlet flow control valve (19a) which is connected to an inlet side of the inside evaporator (20) and functions as an expansion valve which reduces a pressure of and expands a refrigerant which flows into the inside evaporator in the refrigeration cycle system and an outlet flow regulating valve (19b) which is connected to an outlet side of the inside evaporator (20) and functions as an evaporation pressure regulator which adjusts the pressure to a predetermined target pressure where no frost forms in the inside evaporator (20), and the inlet flow control valve (19a) and the outlet flow regulating valve (19b) displace so that when the valve opening of one increases, the valve opening of the other decreases.

Note that, the above reference notations are examples which show the correspondence with specific examples which are described in the later explained embodiments.

DESCRIPTION OF EMBODIMENTS

Below, referring to the drawings, embodiments of the present invention will be explained. In the embodiments, the same component parts are assigned the same reference notations and explanations are omitted.

The flow regulating valve of the present embodiment, as shown inFIGS. 1A and 1B, is a flow regulating valve which functions as both an electric evaporation pressure regulator for frost control and an expansion valve of a refrigeration cycle. The frost control in the present embodiment relates to an inside evaporator. Normally, the outside heat exchanger has a defrosting device which heats frozen moisture to melt it, but in the case of the inside evaporator, the frozen moisture is heated and part becomes steam which ends up being vented to the passenger compartment causing the window glass to fog up, so means for preventing frosting is necessary as a safety measure at the time of operation. Conventional frost preventing means included ones which used a spring type evaporation pressure regulator and ones which adjusted the amount of discharge refrigerant of the compressor (capacity or speed). Each was for a cooling operation.

As opposed to this, the flow regulating valve of the present embodiment is not limited to a cooling operation and, as explained later, can function as an expansion valve and prevent frost in the different modes. That is, in control by the flow regulating valve of the present embodiment, it is made possible to switch between the evaporation pressure regulator (EPR) system which controls a single control motor by electric control and a discharge refrigerant rate adjustment system of a compressor. Below, the structure of a flow regulating valve of the present embodiment will be explained byFIGS. 1A and 1B, while the actions performed in the different operation modes of the flow regulating valve of the present invention will be explained inFIGS. 2 to 7.

Referring toFIGS. 1A and 1B, in the body100, an inlet flow control valve19awhich is connected to the evaporator inlet side and the outlet flow regulating valve19bwhich is connected to the evaporator outlet side are provided. A valve element201of the inlet flow control valve19aand a valve element301of the outlet flow regulating valve19bare joined together by a connecting shaft400in facing directions. The valve element201of the inlet flow control valve19ais driven by a control motor (step motor)500to any position in the up-down direction ofFIG. 1A. The valve element301of the outlet flow regulating valve19balso displaces by the same amount of movement through a connecting shaft400.

The distance “b” between the valve element201and the valve element301becomes larger than the distance “a” between the valve seat part202of the inlet flow control valve19aand the valve seat part302of the outlet flow regulating valve19bwhich are provided at the body100. For this reason, if driving the valve element201in the closing direction (downward direction ofFIG. 1A), the valve element301separates from the valve seat part302and moves in the valve opening direction. The valve element201is made to move to a position where it contacts the valve seat202to set a closed state. At this time, the valve element301and the valve seat302become separated the most resulting in a wide open state.

Conversely, if making the valve element201move in the reverse direction (up direction ofFIG. 1A) and making the valve element301and the valve seat302the closed state, the valve element201and the valve seat202become wide open (seeFIG. 1B). The connecting shaft400connects the inlet flow control valve19aand the outlet flow regulating valve19b, so to prevent refrigerant leakage between valves, an O-ring600is attached. As shown inFIG. 1C, in the present embodiment, the outlet flow regulating valve19bmay be provided with a bypass flow path (bleed port)311which allows a predetermined flow rate even when the valve is closed. This is so as to secure the minimum necessary flow rate of refrigerant even when the valve is closed and the opening is minute and enable the lubricant oil in the refrigerant to lubricate the compressor. Further, this is to prevent the hunting which can easily occur at the time of valve closing or the time of valve opening. The bypass flow path (bleed port)311is not limited to the present embodiment. It may also be provided in all of the later explained embodiments.

The actions and effects of the present embodiment will be explained in detail in the later explained operation modes, but when using the inlet flow control valve19aas an expansion valve, the distance (amount of lift) between the valve element201and the valve seat202is adjusted in a state smaller than the distance between the valve element301and the valve seat302so adjust the amount of lift of the valve element201(this being referred to as the “control opening”). At this time, the distance between the valve element301and the valve seat302is secured sufficiently large so that in the range of adjustment of the amount of lift of the valve element201, the pressure loss of the outlet flow regulating valve19bdoes not change much at all.

When using the outlet flow regulating valve19bas an evaporation pressure regulator (electric EPR), the distance (amount of lift) between the valve element301and the valve seat302is adjusted in a state smaller than the distance between the valve element201and the valve seat202so adjust the amount of lift of the valve element301. Due to this, the inlet flow control valve19a(expansion valve) and outlet flow regulating valve19b(EPR) can be made integral and can be driven by a single actuator, so this is effective for reducing the cost, cutting the number of parts, and improving the mountability. Further, both of the inlet flow control valve19aand the outlet flow regulating valve19bare never simultaneously adjusted in flow rates (controlled), so interference never occurs with control for adjusting the amount of discharge refrigerant of the compressor. Note that, the control motor500may also use a servo motor or linear solenoid or other actuator in addition to a step motor.

A second embodiment of the present invention is an embodiment which is applied to a refrigeration cycle system10for air-conditioning a passenger compartment which is switched among different operating modes of the following cooling mode, heating mode, first dehumidifying heating mode, and second dehumidifying heating mode. Below, referring toFIGS. 2 to 7, the cooling mode, heating mode, first dehumidifying heating mode, and second dehumidifying heating mode will be explained and the functions of the above-mentioned flow regulating valve in the respective modes will be explained. Note that, the flow regulating valve of the first embodiment is not limited to this refrigeration cycle system and can be applied to other refrigeration cycle systems which are switched between different operation modes. Further, the flow regulating valves of the other embodiments which are explained later can be applied to not only this refrigeration cycle system, but also other refrigeration cycle systems.

The overall configuration of the refrigeration cycle system10of the present embodiment becomes as follows next as seen inFIGS. 2 and 3(including broken line parts). A main refrigerant circuit through which a refrigerant circulates is formed by a compressor11, inside condenser12, first expansion valve14, outside heat exchanger15, accumulator21, and the compressor11arranged in that order. Note that, the accumulator21may be omitted or a receiver tank may be used at the condenser outlet. This main refrigerant circuit forms a heating mode as explained later. In this circuit, a first branching point61is provided between the inside condenser12and the first expansion valve14and, furthermore, a second branching point62is provided between the outside heat exchanger15and the accumulator21. Downstream of the second branching point62before reaching the accumulator21, a first shutoff valve17is set for switching the circuit. The passage from downstream of this second branching point62through the first shutoff valve17to the accumulator21will be referred to as the “second refrigerant passage16”.

Further, a passage runs from the second branching point62through the check valve24, inlet flow control valve19a, inside evaporator20, and outlet flow regulating valve19band merges with the main refrigerant circuit at the first merging point63upstream of the accumulator21. The passage from downstream of this second branching point62through the check valve24to the first merging point63will be referred to as the “third refrigerant passage18”. In the main refrigerant circuit, the passage from the first branching point61to the second branching point62will be referred to as the “first refrigerant passage13”. The second refrigerant passage16is also part of the main refrigerant circuit. Further, the passage from the first branching point61which connects with the third refrigerant passage18at the second merging point64downstream of the check valve24will be referred to as the “fourth refrigerant passage22”. A second shutoff valve23with a fixed venturi23ais inserted. The circuit combining the fourth refrigerant passage22and the third refrigerant passage18from the second merging point64forms a bypass refrigerant circuit for the main refrigerant circuit. The passage from the second branching point62through the check valve24to the second merging point64forms the connection refrigerant passage.

At the inlet of the inside condenser12, a temperature sensor Td is provided, while at the outlet, a pressure sensor P and a temperature sensor Th are provided. At the outlet of the outside heat exchanger15, a temperature sensor Ts is provided. At the cooling fins of the inside evaporator20, a temperature sensor Tefin is provided, while at the outlet, a temperature sensor Te is provided. In addition to these detection signals, sensors necessary for a car air-conditioning system (auto air-conditioning control system using target vent temperature TAO) are provided.

The car air-conditioning system which uses the refrigeration cycle system10of the present embodiment is provided with a heating, venting, and air-conditioning unit (HVAC)1. The heating, venting, and air-conditioning unit1is arranged inside from an instrument panel at a frontmost part of the passenger compartment. Inside the air-conditioner case which forms an outer shell, a blower2, inside evaporator20of the refrigeration cycle system10, air mix door3, and inside condenser12of the refrigeration cycle system10are housed. In the present embodiment, a heater core34which uses engine cooling water is provided together with the inside condenser12of the refrigeration cycle system10so as to heat the air-conditioning air. Note that, the heater core34may also be omitted.

At the upstream-most side of the flow of fan air of the heating, venting, and air-conditioning unit1, a lead-in port which leads in the inside air (air inside passenger compartment) and the outside air (air outside passenger compartment) and an inside/outside air switching door4which switches between the inside air and the outside air are provided. At the downstream side of the flow of air of the inside evaporator20, a heating use air passage36which runs air toward the inside condenser12and a cooling air bypass passage35, that is, two air passages, are formed by a partition wall. An air mix door3is used to control the ratio of air flow. Furthermore, at the downstream side of these air passages, after a mixing space, vents are arranged which vent temperature adjusted air to the passenger compartment. As the vents for venting air to the passenger compartment, face vents which vent air toward the upper body of the passengers in the passenger compartment, foot vents which vent air toward the feet of the passengers, defrost vents (not shown) which vent air toward the inside surface of the front window glass of the vehicle (not shown), etc. are provided. As the heating, venting, and air-conditioning unit (HVAC), various examples of layout and structure are known. The above heating, venting, and air-conditioning unit1is not limited in layout and structure to those of the present embodiment.

The different modes in the car air-conditioning system which uses the refrigeration cycle system10of the present embodiment will be explained below.

Cooling Mode

In the cooling mode, a control device of the air-conditioning system uses the first shutoff valve17to close the second refrigerant passage16and uses the second shutoff valve23to close the fourth refrigerant passage22. Furthermore, it uses the first expansion valve14to make the first refrigerant passage13the wide open state. Due to this, in the refrigeration cycle system10, as the cooling mode, a refrigerant flow path such as shown by the arrows ofFIG. 2is switched to. By the configuration of this refrigerant flow path, the control device uses the target vent temperature TAO, the detection signals of the group of sensors, etc. as the basis to determine the operating states of the various control equipment which are connected to the control device (control signals which are output to the various control equipment).

For example, the refrigerant discharge ability of the compressor11, that is, the control signal which is output to the electric motor11bof the compressor11, is determined as follows. First, based on the target vent temperature TAO, a control map which is stored in the control device in advance is referred to so as to determine the target evaporator temperature TEO of the inside evaporator20. Further, the difference of this target evaporator temperature TEO and the detection values of the evaporator temperature sensors Tefin and Te is used as the basis to determine the control signal which is output to the electric motor11bof the compressor11so that the temperature of the air which passes through the inside evaporator20approaches the target vent temperature TAO using a feedback control technique. Further, regarding the control signal which is output to the second expansion valve constituted by the inlet flow control valve19a, the opening degree of the second expansion valve constituted by the inlet flow control valve19ais determined so that the degree of subcooling of the refrigerant which flows into the inlet flow control valve19aapproaches a target degree of subcooling which is determined in advance so as to make the COP (coefficient of performance) approach the maximum value. The inlet flow control valve19aand the outlet flow regulating valve19bare made integral to form the flow control valve19of the first embodiment.

Regarding the control signal which is output to the servo motor of the air mix door36, this is determined so that the air mix door36closes the air passage36of the heater core34and inside condenser12and so that the total flow rate of the fan air after passing through the inside evaporator20passes through the cooling air bypass passage35. Therefore, in the refrigeration cycle system10at the time of the cooling mode, the high pressure refrigerant which is discharged from the compressor11flows to the inside condenser12. At this time, the air mix door3closes the air passage of the heater core34and inside condenser12, so the refrigerant which flows to the inside of the inside condenser12flows out from the inside condenser12with almost no heat exchange with the passenger compartment fan air. The refrigerant which flows out from the inside condenser12flows through the first refrigerant passage13to the inside of the first expansion valve14. At this time, the first expansion valve14makes the first refrigerant passage13the wide open state, so the refrigerant which flows out from the inside condenser12flows into the outside heat exchanger15without being reduced in pressure by the first expansion valve14. Further, the refrigerant which flows into the outside heat exchanger15discharges heat to the outside air which is blown from the blower fan at the outside heat exchanger15.

The refrigerant which flows out from the outside heat exchanger15flows through the third refrigerant passage18to the inlet flow control valve19awhich is arranged at the inlet side of the inside evaporator20and is reduced in pressure and expanded at the inlet flow control valve19auntil becoming a low pressure refrigerant. The low pressure refrigerant which is reduced in pressure at the inlet flow control valve19aflows into the inside evaporator20where it absorbs heat from the passenger compartment fan air which is blown from the blower2so as to evaporate. Due to this, the passenger compartment fan air is cooled.

The refrigerant which flows out from the inside evaporator20flows into the outlet flow regulating valve19bwhich is arranged at the outlet side of the inside evaporator20. At this time, the outlet flow regulating valve19bis large in amount of valve lift and close to the fully open state and is in a state of a large opening area, so refrigerant flows into the accumulator21where it is separated into gas and liquid without any pressure drop occurring. Further, the gas phase refrigerant which was separated at the accumulator21is sucked into the compressor11from the suction side where it is again compressed at the compressor11. Note that, the liquid phase refrigerant which is separated at the accumulator21is accumulated inside of the accumulator as excess refrigerant which is not required for making use of the cooling capacity which the cycle demands.

As explained above, in the cooling mode, the refrigerant is reduced in pressure and expanded at the inlet flow control valve19a. On the other hand, the mechanically connected outlet flow regulating valve19bis large in amount of valve lift and close to the fully open state and is in a state of a large opening area, so no pressure drop occurs and there is no effect on the technique of feedback control of the electric compressor11on the target evaporator temperature TEO.

Heating Mode

Next, referring toFIG. 3, the heating mode will be explained. In the heating mode, the control device uses the first shutoff valve17to open the second refrigerant passage16and uses the second shutoff valve23to close the fourth refrigerant passage22(fully closed). Furthermore, it uses the inlet flow control valve19aof the second expansion valve19to close (fully close) the third refrigerant passage18. Due to this, in the refrigeration cycle system10, as shown by the arrows ofFIG. 3, the refrigerant flow path through which the refrigerant flows is switched to. By this configuration of the refrigerant flow path, the control device uses the target vent temperature TAO, detection signals of the group of sensors, etc. as the basis to determine the operating states of the various control equipment which is connected to the control device (control signals which are output to the various control equipment). For example, the refrigerant discharge ability of the compressor11, that is, the control signal which is output to the electric compressor, is determined in the following way. First, the target vent temperature TAO is used as the basis to refer to the control map which is stored in the control device in advance to determine the target condenser temperature TCO of the inside condenser12.

Further, the difference between this target condenser temperature TCO and the detection value of the discharge temperature sensor is used as the basis to determine the control signal which is output to the electric compressor so that the temperature of the air which passes through the inside condenser12approaches the target vent temperature TAO using the feedback control technique. Further, regarding the control signal which is output to the first expansion valve14, the cooling rate of the refrigerant which flows into the first expansion valve14is determined so as to approach a predetermined target subcooling degree so as to make the COP approach the maximum value. Regarding the control signal which is output to the servo motor of the air mix door3, the signal is determined so that the air mix door3closes the cooling air bypass passage35and the entire flow of the fan air after passing through the inside evaporator20passes through the air passage36of the heater core34and inside condenser12. Therefore, in the refrigeration cycle system10at the time of the heating mode, the high pressure refrigerant which is discharged from the compressor11flows into the inside condenser12. The refrigerant which flows into the inside condenser12is blown from the blower2and exchanges heat with the passenger compartment fan air which passes through the condenser12so as to discharge heat. Due to this, the passenger compartment fan air is heated.

The refrigerant which flows out from the inside condenser12flows through the first refrigerant passage13to the first expansion valve14and is reduced in pressure and expands at the first expansion valve14until becoming a low pressure refrigerant. Further, the low pressure refrigerant which is reduced in pressure at the first expansion valve14flows into the outside heat exchanger15where it absorbs heat from the outside air which was blown from the blower fan. The refrigerant which flows out from the outside heat exchanger15flows through the second refrigerant passage16into the accumulator21where it is separated into a gas and liquid. Further, the gas phase refrigerant which is separated at the accumulator21is sucked in from the suction side of the compressor11and is again compressed by the compressor11. Note that, the liquid phase refrigerant which was separated by the accumulator21is accumulated inside of the accumulator as excess refrigerant which is not needed for making use of the cooling capacity which the cycle demands. Note that, the third refrigerant passage18is closed by the inlet flow control valve19a, so refrigerant does not flow into the inside evaporator20.

As explained above, in the heating mode, the third refrigerant passage18is closed by the inlet flow control valve19a. On the other hand, the outlet flow regulating valve19bof the mechanically connected second expansion valve becomes an open state with a large opening area, so the inside evaporator20and the accumulator21are constantly fixed to a communicated state.

Next, referring toFIGS. 4 and 5, a first dehumidifying heating mode will be explained. In the first dehumidifying heating mode, the control device uses the first shutoff valve17to close the second refrigerant passage16and uses the second shutoff valve23to close the fourth refrigerant passage22. Further, the first expansion valve14and the inlet flow control valve19aare made the throttled state or fully open state. Due to this, the refrigeration cycle system10, in the same way as the cooling mode, as shown by the arrows ofFIG. 4, is switched to the refrigerant flow path through which the refrigerant flows. Note that, in the first dehumidifying heating mode, the outside heat exchanger15and the inside evaporator20are connected in series with respect to the refrigerant. Due to this configuration of the refrigerant flow path, the control device uses the target vent temperature TAO, detection signals of the group of sensors, etc. as the basis to determine the operating states of the various control equipment which are connected to the control device (control signals which are output to the various control equipment). For example, the control signal which is output to the servo motor of the air mix door3is determined so that the air mix door3closes the cooling air bypass passage35and the entire flow of the fan air which passes through the inside evaporator20passes through the air passage36of the heater core34and inside condenser12, or the air mix door3is set to a suitable opening position. Further, the first expansion valve14and inlet flow control valve19aare changed in opening in accordance with the target temperature of the vent air which is vented to the passenger compartment, that is, the target vent temperature TAO.

Specifically, along with a rise in the target temperature of the vent air which is vented into the passenger compartment, that is, the target vent temperature TAO, the control device uses the first expansion valve14to reduce the pressure of the outside heat exchanger15from the high pressure of the outlet of the inside condenser12to a predetermined intermediate pressure. The inlet flow control valve19areduces the pressure of and expands the refrigerant from the intermediate pressure to the low pressure refrigerant. As shown inFIG. 5, the intermediate pressure which is reduced to by the first expansion valve14is set to a pressure which gives a refrigerant temperature higher than the outside air temperature when the outside heat exchanger15discharges heat and is set to a pressure which gives a refrigerant temperature lower than the outside air temperature when it absorbs heat. The inlet flow control valve19aadjusts the pressure which is reduced from the intermediate pressure of the first expansion valve14so that the pressure of the outlet of the inside condenser12becomes the target vent temperature TAO.

The high pressure refrigerant which is discharged from the compressor11flows into the inside condenser12where it exchanges heat with the passenger compartment fan air which was cooled by the inside evaporator20and dehumidified and discharges heat. Due to this, the passenger compartment fan air is heated. The refrigerant which flows out from the inside condenser12flows through the first refrigerant passage13to the first expansion valve14. At this time, the first expansion valve14reduces the pressure of the refrigerant to a predetermined pressure, then the refrigerant which flows into the outside heat exchanger15exchanges heat with the outside air which is blown from the blower fan by the outside heat exchanger15. The refrigerant which flows out from the outside heat exchanger15flows through the third refrigerant passage18into the inlet flow control valve19aand is reduced in pressure and expanded at the inlet flow control valve19auntil becoming a low pressure refrigerant. The low pressure refrigerant which is reduced in pressure by the inlet flow control valve19aflows into the inside evaporator20where it absorbs heat from the passenger compartment fan air which was blown from the blower2and evaporates. Due to this, the passenger compartment fan air is cooled.

Further, the refrigerant which flows out from the inside evaporator20flows into the outlet flow regulating valve19bwhich is arranged at the outlet side of the inside evaporator20. At this time, the outlet flow regulating valve19bis large in amount of valve lift and close to the fully open state and is in a state of a large opening area, so refrigerant flows from the accumulator21to the suction side of the compressor11where it is again compressed by the compressor11without any pressure drop occurring. In the above way, even in the first dehumidifying heating mode, the inlet flow control valve19ais used to reduce the pressure for expansion. On the other hand, the outlet flow regulating valve19bwhich is mechanically connected with the inlet flow control valve19ais large in amount valve lift and close to the fully open state and is in a state of a large opening area, so no pressure drop occurs and there is no effect on the feedback control technique of the electric compressor11for the target evaporator temperature TEO.

Next, referring toFIG. 6, a second dehumidifying heating mode will be explained. Up to now, the outlet flow regulating valve19bwas made a fully open state, but in this mode, it functions as an evaporation pressure regulator (EPR) which is electrically controlled by a single control motor for preventing frost. In the second dehumidifying heating mode, the control device uses the first shutoff valve17to open the second refrigerant passage16and uses the second shutoff valve23to open the fourth refrigerant passage22. The second shutoff valve23houses a fixed venturi part23ainside of it and reduces the pressure of and expands the refrigerant. Further, both the first expansion valve14and the outlet flow regulating valve19bare made the throttled state. Therefore, the refrigeration cycle system10, as shown by the arrows ofFIG. 6, is switched to a refrigerant flow path through which a refrigerant flows. Note that, in the second dehumidifying heating mode, the outside heat exchanger15(main refrigerant circuit) and inside evaporator20(bypass refrigerant circuit) are connected in parallel with respect to the flow of refrigerant.

Due to this configuration of the refrigerant flow path, the control device uses the target vent temperature TAO, detection signals of the group of sensors, etc. as the basis to determine the operating state of the various control equipment which are connected to the control device (control signals which are output to various control equipment). For example, the control signal which is output to the servo motor of the air mix door3is determined so that the air mix door3closes the cold air bypass passage35and the total flow rate of the fan air after passing through the inside evaporator20passes through the air passage36of the heater core34and inside condenser12. The air mix door3is sometimes set to a suitable opening degree position. Further, the control signal which is output to the first expansion valve14is determined so as to give a predetermined opening for a second dehumidifying heating mode.

On the other hand, regarding the control signal which is output to the outlet flow regulating valve19b, the opening of the outlet flow regulating valve19bis determined so that the refrigerant evaporation pressure of the inside evaporator20becomes a predetermined target pressure where no frost is formed. Therefore, in the refrigeration cycle system10at the time of the second dehumidifying heating mode, the high pressure refrigerant which is discharged from the compressor11flows into the inside condenser12, is cooled by the inside evaporator20, exchanges heat with the dehumidified passenger compartment fan air, and discharges heat. Due to this, the passenger compartment fan air is heated.

The refrigerant which flows out from the inside condenser12flows through the first refrigerant passage13to the first expansion valve14and flows from the second shutoff valve23(fixed venturi part23a) through the fourth refrigerant passage22to the inlet flow control valve19a(state of large opening area) and the outlet flow regulating valve19b(frost preventing control opening degree). The high pressure refrigerant which flows into the first expansion valve14is reduced in pressure until becoming a low pressure refrigerant of a lower temperature than the outside air temperature. Further, the low pressure refrigerant, which was reduced in pressure at the first expansion valve14, flows into the outside heat exchanger15and absorbs heat from the outside air which is blown in from the blower fan.

On the other hand, the low pressure refrigerant which flows into the inlet flow control valve19apasses through the inlet flow control valve19ain a state with a large amount valve lift, close to the fully open state, and with a large opening area to flow into the inside evaporator20where it absorbs heat from the passenger compartment fan air which is blown in from the blower2and evaporates, whereby the passenger compartment fan air is cooled. The refrigerant which flows out from the inside evaporator20is reduced in pressure by the outlet flow regulating valve19bwhich is arranged at the outlet side of the inside evaporator20from the predetermined evaporation pressure and flows into the accumulator21.

The refrigerant which flows out from the outside heat exchanger15and the refrigerant which flows out from the inside evaporator20flow from the accumulator21to the suction side of the compressor11and again are compressed at the compressor11. The Mollier chart of the second dehumidifying heating mode is shown inFIG. 7. The outlet flow regulating valve19buses the evaporation pressure regulator (EPR) for frost prevention to maintain the evaporation pressure of the refrigerant in the evaporator at a constant pressure (set pressure). The valve element301of the outlet flow regulating valve19bis driven by a motor (step motor)500to any position in the up-down direction ofFIG. 1A. For this reason, the problems (1) to (6) explained in the background art for the prior art spring type evaporation pressure regulator are solved.

In the second dehumidifying heating mode of the present embodiment, the pressure of the low pressure refrigerant which flows out from the outside heat exchanger15and the pressure of the low pressure refrigerant which flows out from the outlet flow regulating valve19bbecome a pressure equal to the accumulator21. Even if the outlet flow regulating valve19bis set fully open to try to adjust the flow rate by the inlet flow control valve19a, the pressure of the inside evaporator20ends up being pulled along by the pressure of the accumulator21, so the outlet flow regulating valve19bhas to be used for flow rate control. Further, the third refrigerant passage18is provided with a check valve24, so refrigerant will not flow back from the fourth refrigerant passage22to the outlet side of the low pressure outside heat exchanger15. Note that, the second shutoff valve23may intermittently open and close to adjust the refrigerant flow rate when the amount of heat absorbed at the inside evaporator20is small.

As explained above, at the time of the second dehumidifying heating mode, different from the time of the first dehumidifying heating mode, the refrigerant flow path becomes one where the outside heat exchanger15and the inside evaporator20are connected in parallel to the flow of refrigerant, but even when the outlet refrigerant pressure of the outside heat exchanger15is lower than the refrigerant evaporation pressure of the inside evaporator20, it is possible to use the outlet flow regulating valve19bto maintain the evaporation pressure of the inside evaporator20at a target pressure where no frost occurs without using additionally an EPR or other parts. Furthermore, it is possible to flexibly change the target pressure in accordance with the input values of the group of various sensors or fan volume, so it is possible to prevent the vent temperature or air flow from becoming more excessive than necessary.

Regarding the control signal which is output to the first expansion valve14, the outlet side of the outside heat exchanger outlet may be provided with a temperature sensor Ts, and the target superheating degree and superheating degree at the outside heat exchanger outlet side (difference from detected value of temperature sensor Ts etc.) may be used as the basis to determine the control signal which is output to the first expansion valve14so that the superheating degree at the outlet side of the outside heat exchanger15approaches the target superheating degree using a feedback control technique etc.

At the time of the second dehumidifying heating mode, the outlet flow regulating valve19bis used for frost control of the inside evaporator20. On the other hand, at the time of the cooling mode or first dehumidifying heating mode, the inlet flow regulating valve19ais set to the control opening degree and the outlet flow regulating valve19bis at the fully open state, so in these modes, it is sufficient to perform frost control of the inside evaporator20by the amount of compressor discharge refrigerant (compressor speed and capacity).

Next, the switching control of these modes will be explained with reference to the control flow chart ofFIG. 8. At step S1000, the different sensor outputs and panel output are input. To calculate the target vent temperature TAO, the outside air temperature Tam, inside air temperature, amount of sunlight, and set temperature are the general input items. At step S2000, the input values at step S1000are used as the basis to calculate TAO. At step S3000, the ON or OFF state of the A/C switch is judged. Here, the A/C switch, in the same way as current car air-conditioners, is defined as a switch which turns the function of cooling (or dehumidifying) the inside evaporator20ON and OFF. When the A/C switch is OFF, the heating mode is shifted to. When the A/C switch is ON, the next step S4000is shifted to.

At step S4000, if TAO is smaller than the set value α, the cooling mode is shifted to. When it is higher than α, the dehumidifying mode is judged and the next step S5000is shifted to. At step S5000, if the outside air temperature Tam is low (for example T1or less), the operation shifts to a second dehumidifying mode where a high vent temperature is obtained even in the low temperature region. When higher than T1, the routine proceeds to the next step S6000. At the step S6000, when setting and running an operation mode, the detection value TAV of the vent temperature (passenger compartment vent air temperature) and the target vent temperature TAO are compared. When a predetermined value β or less, the system is operated as is in the first dehumidifying heating mode. When a discrepancy of a predetermined value or more occurs, the system shifts to a second dehumidifying heating mode where a higher vent temperature is obtained.

The mode where there are flows of refrigerant at the inside condenser12and the inside evaporator20and heat is exchanged between them is a dehumidifying heating mode. The difference between the first dehumidifying heating mode and the second dehumidifying heating mode is the flow of refrigerant of the outside heat exchanger15. In the case of the first dehumidifying heating mode, the outside heat exchanger15becomes serial in flow with the inside evaporator20. In the case of the second dehumidifying heating mode, the outside heat exchanger15becomes parallel in flow with the inside evaporator20. The first dehumidifying heating mode and the second dehumidifying heating mode, as shown inFIG. 8, are selectively used in accordance with the target vent temperature TAO, the outside air temperature Tam, etc.

Next, a flow regulating valve19of another embodiment will be explained. (Points of differences from the first embodiment or prior embodiments will be explained. In addition, points which are similar to the first embodiment or prior embodiments will be omitted.)

In the case of the first embodiment, as seen inFIG. 1A, the connection hole206from the outside heat exchanger15and the connection hole305from the inside evaporator20are arranged adjoining each other. Compared with the connection hole206from the outside heat exchanger15, the pressure of the connection hole305is low, so there is a pressure difference between the two. On the other hand, in the present embodiment, as seen inFIG. 9, the connection hole205to the inside heat exchanger20and the connection hole305from the inside evaporator20are arranged adjoining each other. The pressure loss inside the inside evaporator20is small, so the difference between the inlet and outlet is small and the amount of leakage of the through part of the connecting shaft400is small, so the O-ring of the through part can be omitted. The rest is similar to the case of the first embodiment.

Compared with the third embodiment, the valve element301of the outlet flow regulating valve19bis moved along a sliding hole which is provided at the valve receiver303in the valve lift direction. At the inside of the valve element301, a spring309is housed. This pushes the valve element301in a direction contacting the valve seat302. The rest is similar to the first and third embodiments. As shown inFIG. 10B, in the present embodiment, the valve element301and the connecting shaft400are not connected. If using the motor500to drive the valve element201in the closing direction, the connecting shaft400also descends. If the bottom end of the connecting shaft400contacts the valve element301, the valve element301is made to move in the opening direction. If driving the valve element201in the opening direction, it moves in the closing direction by the spring309in accordance with the rise of the connecting shaft400.

In the present embodiment, assembly work to connect the valve element301to the connecting shaft400is unnecessary, so assembly becomes easy. Further, when the valve element301approaches the valve seat302and closes the valve, the connecting shaft400separates from the valve element301, so there is the advantage that an excessive load acts on the valve element301.

Compared with the first embodiment, the body part100is divided into a block102of an inlet flow control valve19aand a block101of an outlet flow regulating valve19b. Further, the connecting shaft400to which the valve elements201and301are attached is inserted into the shaft guide410to form a subassembly450. In the present embodiment, the subassembly450is attached between the blocks101and102. The connecting shaft400and motor are joined inside the motor500. The motor500and the blocks101and102are assembled by connection by through bolts601. In the present embodiment, the body side is also divided into the blocks101and102, so body can be easily worked. Further, it is possible to use only the block101of the inlet flow control valve for use as an electric expansion valve, so the parts can be shared. Furthermore, the valve elements201and301form the subassembly450, so the assembly work becomes simpler.

Compared with the fifth embodiment, in the same way as the fourth embodiment, a spring309is provided which biases the valve element301in the closing direction. In the present embodiment, at the time of assembly, there is no need to connect the motor and the connecting shaft400, so further assembly becomes easy. Further, after closing, the pushrod510is separated, so there is the advantage that the valve element301is not acted on by an excess load in the same way as the fourth embodiment.

The seventh embodiment shows an embodiment which makes the outlet flow regulating valve19ba slide valve structure. The piston360which is fastened to the connecting shaft400slides inside of the cylinder350. The cylinder350is provided with an opening part307which communicates with the connecting hole305from the inside evaporator20. The piston360is provided with an opening hole308of a shape which increases in opening area if the connecting shaft400descends (downward direction ofFIG. 13B). That is, if the connecting shaft400descends, the outlet flow regulating valve19bincreases in the area of the opening part which is formed by the piston360and cylinder350. On the other hand, the valve element201approaches the valve seat202whereby the valve opening decreases and reaches a closed state. When the connecting shaft400rises, the valve opening changes in the opposite way.

In the inside evaporator20, the liquid refrigerant evaporates to form a gaseous refrigerant, so large volume gaseous refrigerant flows to the outlet flow regulating valve19b. In the present embodiment, by employing a slide valve structure, it is possible to make the cylinder diameter larger than the pipe diameter and thereby secure the opening area of the valve. Further, the slide valve can reduce the drive force of the motor since the force due to the pressure difference upstream and downstream of the valve does not act in the valve lift direction. Furthermore, in the present embodiment, by making the cylinder350a structure to be inserted into the body, the valve element201can be inserted from the slide valve side. Assembly in one direction from the motor mounting hole becomes possible. Furthermore, if giving a margin to the closing position of the slide valve and the contact position of the cylinder350and the piston360(clearance “c” ofFIG. 13B), there is no mechanical contact at the time of valve closing, so even large error in the stopping position of the motor can be allowed. The outlet flow regulating valve19bmay be provided with a bypass flow path (bleed port) which allows a predetermined flow rate even when closed.

The eighth embodiment shows an embodiment where the outlet flow regulating valve19band the inlet flow control valve19aare comprised of rotary valves. In the present embodiment, the valve element308′ of the outlet flow regulating valve19band the valve element208′ of the inlet flow control valve19aare made to rotate through the connecting shaft400by the motor500. The opening parts of the valve element308′ and the valve element208′ are provided so that the changes in area become opposite with respect to rotation of the valve elements (seeFIGS. 14B and 14C). According to the present embodiment, even if the outlet flow regulating valve19band the inlet flow control valve19aare superposed, the total height can be made lower and mounting becomes easy. Further, rotational force of the control motor500does not have to be converted to linear motion, so the control motor can be simplified. Furthermore, in the same way as the slide valve, there is no mechanical contact at the time of valve closing, so even if the error in stopping position of the motor is large, this would be allowable.

The ninth embodiment adds to the inlet flow control valve19aa sub valve203which reduces the opening area of the inlet flow control valve19aif the valve element201is separated from the valve seat202by a predetermined amount or more. When using the outlet flow regulating valve19bto adjust the evaporation pressure of the evaporator, if the refrigerant flow rate is small, the clearance between the valve element301and the valve seat302becomes excessively small and sometimes flow rate control becomes difficult. According to the present embodiment, due to the sub valve203, by reducing the opening of the inlet flow control valve19a, the characteristic as shown by the valve opening characteristic ofFIG. 15Bis obtained and flow rate control by the outlet flow regulating valve19bbecomes easy. At the valve opening characteristic ofFIG. 15B, the position C is the case where the connecting shaft400is at its topmost position and the valve element201is seated on the valve seat201. It is the valve opening characteristic when being made to move downward from C to B and A.

The flow regulating valve19of the present invention can be applied to not only the second embodiment, but also the next refrigeration cycle system.

Referring toFIG. 16, a 10thembodiment will be explained. A solenoid valve40is provided which opens and closes the flow path between the discharge side of the compressor11and the outside heat exchanger15. The solenoid valve41opens and closes the fifth refrigerant passage16′. Downstream of the inside condenser12, a fixed venturi which decreases the pressure of the refrigerant is arranged. At the passage which bypasses the fixed venturi42, a solenoid valve43is set. The first expansion valve14adjusts the refrigerant flow rate to the outside heat exchanger at the time of heating to reduce the pressure of the refrigerant. At the time of cooling, the first expansion valve14is bypassed. The check valve24is set to enable flow from the outside heat exchanger15to the inlet flow control valve19a. The flow regulating valve19, in the same way as the second embodiment, comprises an inlet flow control valve19aand an outlet flow regulating valve19b.

The operating modes of the 10th embodiment will be explained. In the cooling mode, the solenoid valve40is opened and the solenoid valves41and43are closed. The flow of refrigerant is parallel to the flow of the compressor11→outside heat exchanger15→check valve24→inlet flow control valve19a→evaporator20→accumulator21→compressor11and becomes compressor11→inside condenser12→fixed venturi42→outlet flow regulating valve19b. The latter flow passes through the fixed venturi42, so the flow resistance is high. A large portion of the refrigerant flows to the outside heat exchanger15side, the outside heat exchanger15discharges heat to the outside of the vehicle, then the inside evaporator20absorbs heat for the cooling operation.

Referring toFIG. 17, the cooling mode will be explained on a Mollier chart. The refrigerant which flows from the compressor outlet “a” to the outside heat exchanger15discharges heat to the outside air and changes to the point of the outside heat exchanger outlet “b”. On the other hand, the refrigerant which flows to the inside condenser12does not discharge heat when the air mix door3is closed, so changes to the point of the fixed venturi outlet “d”. Ideally, if there is no pressure loss at the inside condenser12side, the point “a” and the point “d” become the same. The refrigerants at the point “c” and the point “d” merge and result in enthalpy of the inlet point “e” of the inlet flow control valve19a. The refrigerant which flows to the outside heat exchanger15side is large, so the point “e” becomes close to the point “c”. The refrigerant is reduced in pressure at the inlet flow control valve19aand becomes low temperature, low pressure refrigerant at the point “f”. Further, the refrigerant flows into the inside evaporator20where it absorbs heat from the passenger compartment air and the outlet of the inside evaporator20becomes the point “g” (outlet flow regulating valve19bbecomes wide open state). After this, the refrigerant passes through the accumulator21and reaches the compressor inlet “h”. If there is no pressure loss at the flow path from the outlet of the inside evaporator20to the compressor inlet, the point “g” and the point “h” become the same.

At the heating mode, the solenoid valve41is opened and the solenoid valves40and43are closed. Further, the inlet flow control valve19ais set to the closed state and closes the flow path to the inside evaporator20. The flow of the refrigerant becomes the compressor11→inside condenser12→first expansion valve14→outside heat exchanger15→solenoid valve41→accumulator21→compressor11. The inside condenser12is used to discharge heat into the passenger compartment, while the outside heat exchanger15is used to absorb heat from outside the vehicle for the heating operation.

The 10th embodiment includes a moderate cooling mode. This mode opens the solenoid valves40and43and closes the solenoid valve41. Compared with the cooling operation, the fixed venturi42is bypassed by the solenoid valve43. Due to this, the amount of refrigerant which flows to the inside condenser12is increased and the refrigerant is not only cooled, but also reheated by the inside condenser12.

At the dehumidifying heating mode, the solenoid valve41is opened and the solenoid valves40and43are closed. The refrigerant passes through the compressor11→inside heat exchanger12, then branches. One parallel circuit uses the fixed venturi42to reduce the pressure of the refrigerant, renders the inlet flow control valve19athe open state, runs refrigerant through it, absorbs heat at the inside evaporator20, and dehumidifies the air of the passenger compartment. The outlet flow regulating valve19badjusts the refrigerant flow rate to maintain the predetermined evaporation pressure and prevent frost. The other parallel circuit runs through the first expansion valve14→outside heat exchanger15→solenoid valve41→accumulator21→compressor11and absorbs heat from outside the vehicle at the outside heat exchanger15. This is basically the same as the second dehumidifying heating mode of the second embodiment.

FIG. 18shows an 11th embodiment when changing the solenoid valve at the discharge side of the compressor11of the 10th embodiment to a three-way valve50. Here, an example which streamlines the configuration to eliminate the “moderate cooling mode” operation. Furthermore, the solenoid valve43and its flow path are eliminated. The rest is the same as the 10th embodiment. The operation is also similar.

REFERENCE SIGNS LIST

19ainlet flow control valve

19boutlet flow regulating valve