JP3980186B2 - Heat pump type automotive air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump type automotive air conditioner that uses a refrigerant to cool and heat a vehicle interior, and in particular, quickly cools refrigerant that has accumulated in an outdoor condenser to a heating cycle when the operation mode is switched to heating operation. And it relates to what can be returned in large quantities.
[0002]
[Prior art]
For example, as shown in FIG. 6, a heat pump type automotive air conditioner is provided with an indoor heat exchanger (indoor condenser) 5 called a sub condenser in a unit 1, and heats high-temperature and high-pressure refrigerant compressed by a compressor 6. This system is used as a heat source. That is, both the cooling and heating are performed by cycle operation using a refrigerant to cool and cool the passenger compartment. An outdoor heat exchanger (outdoor condenser) 7 called a main condenser is provided outside the unit 1, and the operation mode is switched by switching a condenser that functions between a heating operation and a cooling operation by a four-way valve 11. The refrigerant discharged from the compressor 6 is introduced into the main condenser 7 during the cooling operation, and is directly introduced into the sub condenser 5 by bypassing the main condenser 7 through the bypass pipe 13 during the heating operation. Hereinafter, the refrigeration cycle formed during the cooling operation is referred to as a cooling cycle, and the refrigeration cycle formed during the heating operation is referred to as a heating cycle.
[0003]
In such a heat pump type automotive air conditioner, a heating cycle in which the main condenser 7 is bypassed during the heating operation is performed. Therefore, if excessive refrigerant accumulates in the main condenser 7, the amount of refrigerant circulating in the heating cycle may be insufficient. There is. In view of this, a refrigerant recovery system is currently developed in which a refrigerant recovery pipe 14 and an electromagnetic valve 15 that opens and closes the refrigerant recovery pipe 14 are provided so that the so-called stagnation refrigerant staying in the main condenser 7 when the heating operation is started is returned to the suction side of the compressor 6. (See, for example, JP-A-9-109669).
[0004]
In addition, in order to improve the heating performance, such a heat pump automobile air conditioner includes a heater core system that uses engine coolant as a heat source in addition to the heat pump system that uses a refrigerant as a heat source. In addition, normally, a dehumidifying function is incorporated (realization of dehumidifying heating) to prevent fogging of the windshield so as to ensure safe driving. Furthermore, it can also be used as a car air conditioner for electric vehicles that cannot use engine coolant in the first place.
[0005]
[Problems to be solved by the invention]
In the refrigerant recovery system shown in FIG. 6, the refrigerant is recovered from the inlet of the main condenser 7, and the refrigerant staying in the main condenser 7 is the inlet of the main condenser 7 → the four-way valve 11 → the refrigerant recovery pipe 14. → Takes the path of the inlet of the accumulator 10 and is collected in the heating cycle.
[0006]
However, in a subsequent experiment, in such a conventional refrigerant recovery method (path), that is, recovery from the inlet of the main condenser 7, the refrigerant staying in the main condenser 7 by the refrigerant recovery pipe 14 at the time of starting the heating operation is used. It was found that even when trying to recover by returning to the suction side of the compressor 6, the recovery amount is small and the recovery time is long. The reason is considered that the refrigerant recovery from the inlet of the main condenser 7 recovers only the gas refrigerant since it is recovered from the condenser inlet (see FIG. 7). That is, in the refrigerant recovery from the inlet of the main capacitor 7, the refrigerant must be evaporated by the pressure difference and recovered as a gas refrigerant, so that the recovery amount is small and the recovery time is also long. For example, conventionally, the recovery time has been set to 150 seconds.
[0007]
Further, even when the system was restarted while the passenger compartment was warm, the amount collected was small and the collection took time as described above.
[0008]
In any case, if the refrigerant recovery amount from the main condenser 7 is small during the heating operation, the refrigerant amount in the heating cycle cannot be properly maintained, and the heating operation is performed in a so-called low refrigerant state. There is a risk that the heating performance will deteriorate and the lubricity will decrease.
[0009]
Further, if the operation is continued in a state where the recovered amount is small, i.e., the refrigerant is too low, the compressor suction pressure (saturation pressure) increases and the internal pressure of the main condenser 7 becomes lower than the compressor suction pressure (saturation pressure). The refrigerant flows back to the condenser 7 side, and the refrigerant recovery amount is further reduced.
[0010]
The present invention has been made by paying attention to the above-mentioned problem in the method (recovery path) for collecting the refrigerant staying in the outdoor condenser (main condenser). By changing the refrigerant recovery path, a large amount of refrigerant can be recovered in a short time. It is an object of the present invention to provide a heat pump type automobile air conditioner that can be performed.
[0011]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following means.
[0012]
  (1) A heat pump type automotive air conditioner according to the present invention includes a compressor, an outdoor condenser, an indoor condenser, a pressure reducing means, and an indoor evaporator connected in this order by refrigerant piping, and the refrigerant discharged from the compressor is A bypass pipe for bypassing a condenser and leading to the indoor condenser; a refrigerant flow switching means for guiding the refrigerant discharged from the compressor to the outdoor condenser side during cooling operation and leading to the bypass pipe side during heating operation; In a heat pump type automotive air conditioner comprising a refrigerant recovery pipe for returning the refrigerant remaining in the outdoor condenser to the suction side of the compressor, the refrigerant recovery pipe includes an outlet side of the outdoor condenser and the compressor Opening and closing means connected to the suction side of the refrigerant and opening and closing the refrigerant recovery pipe YesThe refrigerant flow switching means includes a first electromagnetic valve provided in an inlet pipe of the outdoor capacitor and a second electromagnetic valve provided in the bypass pipe, and when heating operation is selected, When the first solenoid valve is opened, the second solenoid valve is closed, and the opening / closing means is opened, the compressor is started, and when the elapsed time after starting the compressor reaches a first predetermined time or more, the first solenoid valve is opened. 1 solenoid valve is closed and the second solenoid valve is opened, and the opening and closing means is closed when the elapsed time after switching the solenoid valve becomes a second predetermined time or more.It is characterized by.
  (2) A heat pump type automotive air conditioner according to the present invention includes a compressor, an outdoor condenser, an indoor condenser, a pressure reducing means, and an indoor evaporator connected in this order by refrigerant piping, and the refrigerant discharged from the compressor is A bypass pipe for bypassing a condenser and leading to the indoor condenser; a refrigerant flow switching means for guiding the refrigerant discharged from the compressor to the outdoor condenser side during cooling operation and leading to the bypass pipe side during heating operation; In a heat pump type automotive air conditioner comprising a refrigerant recovery pipe for returning the refrigerant remaining in the outdoor condenser to the suction side of the compressor, the refrigerant recovery pipe includes an outlet side of the outdoor condenser and the compressor Opening and closing means connected to the suction side of the refrigerant and opening and closing the refrigerant recovery pipe And when the heating operation is selected, a cooling cycle is formed by the refrigerant flow switching means, and the compressor is started with the opening / closing means opened, and an elapsed time after the compressor start is first. The refrigerant flow path switching means switches to a heating cycle when a predetermined time or longer, and the opening / closing means is closed when the elapsed time after switching to the refrigeration cycle becomes a second predetermined time or longer. .
[0014]
(3) The opening / closing means is a pilot differential pressure actuated solenoid valve provided in the refrigerant recovery pipe in a positive direction with respect to the refrigerant recovery direction.
[0015]
(4) A check valve for preventing backflow is provided on the downstream side of the refrigerant recovery pipe in the refrigerant recovery direction of the pilot differential pressure actuated solenoid valve.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
<< First Embodiment >>
FIG. 1 is a schematic configuration diagram showing a heat pump automobile air conditioner according to a first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which is common in FIG.
[0021]
This automotive air conditioner has an air conditioning unit 1 that selectively takes in air inside and outside the vehicle interior (inside and outside air) and blows it out toward a predetermined location in the vehicle interior after air conditioning.
[0022]
This air conditioning unit 1 has a duct 2 for sending the taken-in air toward the passenger compartment, and the inside air inlet and the outside air inlet in this duct 2 in order from the upstream side in the air flow direction indicated by the white arrow. An intake door (not shown) that selectively opens and closes (both not shown), a blower fan 3 that introduces the inside and outside air selected by the intake door into the duct 2 and pumps it downstream, and evaporates the refrigerant. It has an indoor evaporator 4 (hereinafter simply referred to as an “evaporator”) that cools the air, and a sub-condenser 5 that works mainly during heating operation to condense and liquefy the gas refrigerant and heat the air. Although not shown in the drawing, an air mix door for adjusting the ratio of the air passing through the sub-capacitor 5 and the air bypassing the sub-capacitor 5 is rotatably provided on the front surface of the sub-capacitor 5. On the downstream side, various air outlets are formed for blowing out the temperature-adjusted air toward a predetermined place in the passenger compartment.
[0023]
This heat pump type automobile air conditioner performs cooling and dehumidifying heating in the passenger compartment by performing a cycle operation using a refrigerant for both cooling and heating, and has a refrigeration cycle similar to the conventional one.
[0024]
That is, outside the air conditioning unit 1, a compressor 6 that is rotationally driven by a not-illustrated engine via a belt (not shown) and a main capacitor 7 as an outdoor condenser that mainly works during cooling operation are disposed. In the refrigeration cycle, a compressor 6, a main condenser 7, a sub condenser 5, a liquid tank 8, an expansion valve 9 as a decompression means, an evaporator 4, and an accumulator 10 are connected in this order by a refrigerant pipe 12, and a refrigerant is enclosed therein. Configured. The liquid tank 8 separates gas and liquid, stores the liquid refrigerant once, and sends out only the liquid refrigerant to the expansion valve 9, and normally has a function of separating air and removing moisture and foreign matter. The expansion valve 9 expands the liquid refrigerant under reduced pressure to form a low-temperature and low-pressure mist refrigerant that is easy to evaporate, and also has a function of automatically adjusting the refrigerant flow rate by detecting the evaporator outlet temperature (in the case of temperature operation type). Yes. The accumulator 10 is for storing excess refrigerant and separating the gas and liquid to return only the gas refrigerant to the compressor 6. Since the accumulator 10 is a container having a relatively large capacity, the refrigerant is temporarily returned in a liquid state. However, this can be vaporized and returned to the compressor 6, and damage to the compressor 6 due to liquid compression can be prevented.
[0025]
Since the liquid tank 8 and the accumulator 10 usually have some functions in common, it is not always necessary to provide both of them. However, in the present invention, as described later, the liquid refrigerant is supplied from the outlet of the main condenser 7 as a liquid refrigerant. In order to perform the recovery, it is preferable not to omit at least the accumulator 10. Therefore, for example, when the temperature-operated expansion valve 9 is used as the pressure reducing means as in the present embodiment, both the liquid tank 8 and the accumulator 10 are provided. In the case of using a solenoid valve with an orifice (a flow rate switching solenoid valve whose valve position can be switched between a fully opened state and a throttled state), only the accumulator 10 may be provided and the liquid tank 8 may be omitted.
[0026]
In the figure, reference numerals 16, 17 and 18 denote check valves for preventing flow in opposite directions, and reference numeral 19 denotes a condenser fan for sending air to the main condenser 7 and cooling it.
[0027]
In the present embodiment, a three-way valve 20 serving as a refrigerant flow switching means is provided between the discharge port of the compressor 6 and the inlet of the main capacitor 7 in order to switch the condenser that functions between the heating operation and the cooling operation. ing. The three-way valve 20 has one inlet port and two outlet ports. Here, the inlet port of the three-way valve 20 is connected to the discharge side of the compressor 6, and the two output ports of the three-way valve 20 are respectively connected to the inlet of the main condenser 7 and the outlet of the main condenser 7 via the bypass pipe 13. ing. By selectively switching the outlet port communicating with the inlet port, the cooling cycle for guiding the refrigerant discharged from the compressor 6 to the main condenser 7 and the refrigerant discharged from the compressor 6 directly through the bypass pipe 13 are connected. The heating cycle leading to
[0028]
During the cooling operation, the three-way valve 20 is operated to introduce the refrigerant discharged from the compressor 6 into the main condenser 7. That is, the refrigerant discharged from the compressor 6 flows through the three-way valve 20 → the main condenser 7 → the sub condenser 5 → the liquid tank 8 → the expansion valve 9 → the evaporator 4 → the accumulator 10 to form a cooling cycle that returns to the compressor 6. Thereby, in the evaporator 4, heat exchange between the liquid refrigerant and the intake air is performed, the intake air passing around the refrigerant passage is cooled while the liquid refrigerant evaporates, and the vehicle interior is cooled. Further, in the main condenser 7, the heat taken by the evaporator 4 is released to the outside by heat exchange with the outside air, and the gas refrigerant is cooled and condensed into liquid. At this time, for example, the air mix door is set to a fully closed position so that air does not pass through the sub condenser 5, so that the sub condenser 5 hardly functions as a heat exchanger.
[0029]
In contrast, during the heating operation, the three-way valve 20 is operated to introduce the refrigerant discharged from the compressor 6 directly into the sub-capacitor 5 via the bypass pipe 13. That is, without using the main condenser 7, the refrigerant discharged from the compressor 6 flows through the three-way valve 20 → the bypass pipe 13 → the sub condenser 5 → the liquid tank 8 → the expansion valve 9 → the evaporator 4 → the accumulator 10 and returns to the compressor 6. To form a heating cycle. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 6 and bypassing the main condenser 7 by the three-way valve 20 is condensed and liquefied by the sub condenser 5 to dissipate heat, and the air cooled by the evaporator 4 is heated and the vehicle interior is heated. The interior of the vehicle is heated. At that time, the evaporator 4 cools the intake air to perform dehumidification, so that dehumidification heating is realized.
[0030]
In the present invention, the refrigerant is recovered from the outlet of the main condenser 7 as a refrigerant recovery system that returns the refrigerant staying in the main condenser 7 during the heating operation to the suction side of the compressor 6. That is, the refrigerant recovery line 30 is branched and formed by connecting the refrigerant recovery pipe 30 to the outlet pipe of the main capacitor 7 via a three-way connector, and the solenoid valve 31 serving as an opening / closing means is connected to the refrigerant recovery pipe 30 (refrigerant recovery line). The other end of the refrigerant recovery pipe 30 is connected to the inlet of the accumulator 10 via a three-way connector to return the refrigerant. The reason why the solenoid valve 31 is provided is to prevent the refrigerant that has flowed out of the main capacitor 7 during the cooling operation from flowing into the refrigerant recovery line.
[0031]
As described above, if the refrigerant is recovered from the outlet of the main condenser 7, the liquid refrigerant is accumulated in the lower part in the main condenser 7 (see FIG. 7), so that the refrigerant can be recovered in the liquid state. . Therefore, the refrigerant recovery time and the recovery amount are greatly improved as compared with the case of recovery in a gas state.
[0032]
This was confirmed by experiments. For example, when the outside air temperature is −20 ° C., it is possible to recover a refrigerant of 300 grams or more (almost all of the refrigerant in the main condenser 7) in 90 seconds. Further, no back flow was observed even when the collection was continued.
[0033]
Taking this experimental result into consideration, the opening / closing control of the electromagnetic valve 31 is performed as follows. That is, the electromagnetic valve 31 is turned ON for a predetermined time (for example, 90 seconds) after the heating operation is started, and the refrigerant recovery pipe 30 (refrigerant recovery line) is opened. The valve 31 is turned off to close the refrigerant recovery pipe 30 (refrigerant recovery line). During the cooling operation, the solenoid valve 31 is always turned off and the refrigerant recovery pipe 30 (refrigerant recovery line) is closed. Of course, the refrigerant recovery time is not limited to 90 seconds, and for each system, the time required to obtain the required recovery amount may be determined by experiments and set appropriately.
[0034]
Therefore, according to the present embodiment, since the refrigerant recovery from the inlet of the main condenser 7 is changed to the refrigerant recovery from the outlet of the main condenser 7 and is recovered as a liquid refrigerant, the main condenser Thus, a large amount of refrigerant can be recovered in a short time without backflow to 7, and the refrigerant recovery control time (ON time of the solenoid valve 31) can be shortened. And since it becomes possible to always collect a necessary and sufficient amount of the refrigerant staying in the main condenser 7 within the refrigerant collection control time, the refrigerant amount in the heating cycle is always properly maintained during the heating operation. As a result, problems such as a decrease in heating performance and a decrease in lubricity due to heating operation in the state of a low refrigerant are eliminated, and the same performance can be obtained even if the system is operated repeatedly.
[0035]
<< Second Embodiment >>
FIG. 2 is a schematic configuration diagram showing a heat pump automobile air conditioner according to a second embodiment of the present invention. Note that members that are the same as those in FIGS. 1 and 6 are given the same reference numerals, and descriptions thereof are omitted.
[0036]
This automotive air conditioner is a modification of the automotive air conditioner shown in FIG. 1, and is a so-called pilot differential pressure actuated electromagnetic as a solenoid valve 31 for controlling the opening and closing of the refrigerant recovery line when the heating operation is started. The present invention relates to a system using a valve 31a. The pilot differential pressure actuated solenoid valve 31a is cheaper and consumes less power than the direct acting double-flow control type solenoid valve. preferable.
[0037]
Since the pilot differential pressure actuated electromagnetic valve 31a is a valve that can control only the refrigerant flowing in one direction, it is attached in the positive direction with respect to the refrigerant recovery direction (recovered refrigerant flow) indicated by the dotted arrow in the figure. Yes. Since the configuration and operation of the pilot differential pressure actuated electromagnetic valve 31a are well known, description thereof will be omitted.
[0038]
As described above, in the refrigerant recovery system, the outlet of the main condenser 7 and the suction side of the compressor 6 are connected by the refrigerant recovery pipe 30 so that the internal pressure (saturation pressure) of the main condenser 7 is When the pressure is higher than the suction pressure, the refrigerant staying in the main condenser 7 is returned to the suction side of the compressor 6 through the refrigerant recovery pipe 30 from the outlet of the main condenser 7 in a liquid refrigerant state and recovered in the heating cycle. It is a device that made it. However, when the pilot differential pressure actuated electromagnetic valve 31a is used as an open / close control valve for the refrigerant recovery line (refrigerant recovery pipe 30), the electromagnetic valve 31a of the refrigerant recovery line is closed (OFF) after the refrigerant recovery ends. ) State, when the outside air temperature is low (for example, −20 ° C.) and the passenger compartment temperature is about 20 ° C., the internal pressure (saturation pressure) of the main condenser 7 may be lower than the compressor suction pressure. The reverse differential pressure acts on the pilot differential pressure actuated electromagnetic valve 31 a, and the refrigerant may pass through the electromagnetic valve 31 a, and the refrigerant may flow backward from the suction side of the compressor 6 to the main condenser 7 side.
[0039]
Therefore, in the present embodiment, a check valve 32 for preventing backflow is provided on the downstream side of the refrigerant recovery pipe 30 in the refrigerant recovery direction of the pilot differential pressure actuated electromagnetic valve 31a. That is, the check valve 32 is connected from the intake side of the compressor 6 to the main condenser between the pilot differential pressure actuated solenoid valve 31a of the refrigerant recovery line and the intake side of the compressor 6 (more precisely, the inlet of the accumulator 10). It is installed in the direction to stop the flow of the refrigerant to the 7 side.
[0040]
As a result, even in a system using the pilot differential pressure actuated solenoid valve 31a for controlling the refrigerant recovery line, the reverse flow of the refrigerant is prevented by the function of the check valve 32 even in an environment where the reverse flow can occur. The refrigerant is prevented from leaking from the suction side of the compressor 6 to the main condenser 7 side during the heating operation and accumulated in the main condenser 7, and the amount of refrigerant in the heating cycle during the heating operation is appropriately maintained. Can do.
[0041]
Other configurations and operational effects are the same as those in the first embodiment, and thus description thereof is omitted.
[0042]
<< Third Embodiment >>
FIG. 3 is a schematic configuration diagram showing a heat pump type automotive air conditioner according to a third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which is common in FIG.1, FIG.2, and FIG.6, and the description is abbreviate | omitted.
[0043]
This automotive air conditioner is a modification of the automotive air conditioner shown in FIG. 2 and includes two electromagnetic valves 33 and 34 as refrigerant flow path switching means instead of the three-way valve 20 in FIG. It is provided. For example, since the direction of the refrigerant flowing through the pipes to which these solenoid valves 33 and 34 are attached is always constant, these solenoid valves 33 and 34 are also composed of pilot differential pressure actuated solenoid valves in order to minimize the cost increase. Has been.
[0044]
During the cooling operation, the electromagnetic valve 33 provided in the inlet pipe of the main condenser 7 is opened (ON), and the electromagnetic valve 34 provided in the bypass pipe 34 is closed (OFF), so that the refrigerant discharged from the compressor 6 is main. It introduce | transduces into the capacitor | condenser 7, and forms a cooling cycle. On the other hand, during heating operation, the electromagnetic valve 33 provided in the inlet pipe of the main condenser 7 is closed (OFF), and the electromagnetic valve 34 provided in the bypass pipe 34 is opened (ON), and discharged from the compressor 6. The refrigerant is introduced directly into the sub condenser 5 via the bypass pipe 13 to form a heating cycle. Since other basic configurations and operational effects are substantially the same as those of the second embodiment, description thereof is omitted.
[0045]
Hereinafter, opening / closing control of the three solenoid valves 31, 33, 34 at the time of refrigerant recovery will be described. Here, for convenience of explanation, the electromagnetic valve 33 of the main condenser 7 inlet pipe is the first electromagnetic valve, the electromagnetic valve 34 of the bypass pipe 13 is the second electromagnetic valve, and the electromagnetic valve 31 of the refrigerant recovery pipe 30 is the third electromagnetic valve. I will call it.
[0046]
As a method of electromagnetic valve opening / closing control at the time of refrigerant recovery in this refrigeration cycle, first, when heating operation is started, the first electromagnetic valve 33 is closed, the second electromagnetic valve 34 is opened, and the third electromagnetic valve 31 is opened. There is a method in which the refrigerant recovery pipe 30 is opened for a predetermined time in a state where the refrigerant recovery pipe 30 is opened for a predetermined time, that is, in a state where the heating cycle is switched. However, as a result of experiments, in this method, when the saturation pressure of the main condenser 7 becomes too low at low outside air (−20 ° C.), the differential pressure from the low pressure line (compressor suction pressure) is reduced. There is a possibility that the refrigerant staying in the capacitor 7 cannot be sufficiently recovered.
[0047]
Therefore, a refrigerant recovery control as shown in the flowchart of FIG. 4 was devised as a second method.
[0048]
When the heating operation mode is selected manually or automatically (S1), the refrigerant recovery mode is entered. First, as the first stage, the first electromagnetic valve 33 is opened as the initial state of the electromagnetic valve, and the second electromagnetic valve 34 is closed. And the 3rd solenoid valve 31 is opened (S2), and the compressor 6 is started (S3). That is, in the first stage, the refrigerant recovery pipe 30 is opened with the cooling cycle set.
[0049]
Thereafter, the elapsed time since the start of the compressor 6 is counted, and when the first predetermined time (for example, 30 seconds) has elapsed (S4), as the second stage, the first electromagnetic valve 33 is closed and the first electromagnetic valve 33 is closed. 2 Open the solenoid valve 34 (S5). The third solenoid valve 31 remains open. That is, in this second stage, the circuit is switched to the heating cycle while the refrigerant recovery pipe 30 is kept open.
[0050]
Thereafter, the elapsed time since the first electromagnetic valve 33 is closed and the second electromagnetic valve 34 is opened is counted, and when the second predetermined time (for example, 90 seconds) is reached (S6), the third electromagnetic valve 31 is closed (S7), that is, the refrigerant recovery pipe 30 is closed, the refrigerant recovery operation is terminated, and then the above-described heating operation is performed.
[0051]
In this refrigerant recovery method, at the time of refrigerant recovery, first, in the first stage, a cooling cycle is temporarily formed for a first predetermined time (first refrigerant recovery time) (30 seconds after starting the compressor), and the main condenser Compressor discharge pressure is introduced to 7 to increase the pressure in the main condenser 7 and the refrigerant in the main condenser 7 is recovered to the low-pressure cycle side at once (so-called hot gas bypass). After this hot gas bypass, in the next second stage, the circuit is switched to the original heating cycle, and the refrigerant recovery pipe 30 is opened for a second predetermined time (second refrigerant recovery time) (90 seconds after cycle switching). Then, the refrigerant staying in the main capacitor 5 is recovered. In this second stage, due to the introduction of high pressure into the main condenser 7 by the hot gas bypass in the first stage, the saturation pressure is high even at low outside air (−20 ° C. or less), and the difference from the low pressure line Since the pressure is generated, the refrigerant accumulated in the main condenser 7 moves to the low-pressure cycle side due to the differential pressure, and is collected in the heating cycle.
[0052]
Therefore, in this refrigeration cycle, the refrigerant can be recovered even under low outside air of −20 ° C. or lower by using a hot gas bypass.
[0053]
The two-stage refrigerant recovery control described above can also be applied to other embodiments using the three-way valve (circuits in FIGS. 1, 2, and 5).
[0054]
<< 4th Embodiment >>
FIG. 5 is a schematic configuration diagram showing a heat pump automobile air conditioner according to a fourth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which is common in FIG.1, FIG.2, FIG.3 and FIG. 6, and the description is abbreviate | omitted.
[0055]
The air conditioner for automobiles is based on the air conditioner for automobiles shown in FIG. 2, and in order to improve the heating performance by the heat pump, the intake side of the compressor 6 (more strictly, the inlet of the accumulator 10) and the evaporator 4 The refrigerant recovery system of the present invention is applied to a system in which an outdoor evaporator (outdoor heat exchanger) 35 called a sub-evaporator is provided in a low-pressure side refrigerant passage between the outlet and the outlet. The sub-evaporator 35 has a function of heating the refrigerant flowing through the inside by heat exchange with the engine cooling water, and can be called a hot water-refrigerant heat exchanger. In the figure, reference numeral 36 denotes a water valve for causing the engine cooling water to flow through the sub-evaporator 35 to function.
[0056]
By providing such a sub-evaporator 35, even if it is engine cooling water that cannot be used immediately for heating even if heat is exchanged with air due to a low temperature, heat exchange with the refrigerant flowing in the sub-evaporator 35 is possible. Because the refrigerant effectively takes in the heat held by the engine cooling water and is heated (that is, the enthalpy increases), it returns to the compressor 6 and is compressed and pressurized again by the compressor 6. The refrigerant discharged from the compressor 6 becomes a higher temperature refrigerant and is supplied to the sub capacitor 5. As a result, the heat dissipating performance of the sub-capacitor 5 is enhanced, and the heat-exchanged air becomes higher in temperature, so that higher heating performance is exhibited and immediate warming is improved.
[0057]
In the case where the expansion valve 9 is temperature-operated, it is preferable that the heat sensitive part is attached to the outlet of the sub-evaporator 35. Thereby, since the flow rate of the refrigerant is adjusted by the temperature of the refrigerant after being heated by the sub-evaporator 35, a larger amount of the refrigerant circulates when the sub-evaporator 35 is operated, thereby further improving the heating performance. Promoted.
[0058]
Other configurations and operational effects are the same as those of the second embodiment, and thus description thereof is omitted.
[0059]
【The invention's effect】
  As described above, according to the present invention, the refrigerant recovery during the heating operation is performed in the form of liquid refrigerant from the outlet of the outdoor condenser, so that the refrigerant recovery amount and the recovery time can be reduced without backflow to the outdoor condenser. It is greatly improved and a large amount of refrigerant can be recovered in a short time. Accordingly, the amount of refrigerant in the heating cycle can be always properly maintained during the heating operation, and problems such as a decrease in heating performance and a decrease in lubricity due to the heating operation in the state of insufficient refrigerant are resolved. Reliability is improved.Furthermore, since the cooling cycle is first formed at the time of refrigerant recovery, the refrigerant is recovered and then switched to the heating cycle to recover the remaining refrigerant, so that the refrigerant can be used even in low outside air (−20 ° C. or less) by using a hot gas bypass. Recovery is possible, and refrigerant recovery capability is improved.
[0060]
Further, when a pilot differential pressure actuated solenoid valve is used as the refrigerant recovery pipe opening / closing means, the cost increase can be minimized.
[0061]
In addition, when a check valve is provided on the downstream side in the refrigerant recovery direction of the pilot differential pressure actuated solenoid valve in a direction that prevents backflow, the refrigerant leaks to the outdoor condenser side during heating operation, and the refrigerant enters the outdoor condenser. Accumulation is prevented, and the amount of refrigerant in the heating cycle during heating operation can always be maintained appropriately.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a heat pump automobile air conditioner according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram showing a heat pump automotive air conditioner according to a second embodiment of the present invention.
FIG. 3 is a schematic configuration diagram showing a heat pump automotive air conditioner according to a third embodiment of the present invention.
FIG. 4 is a flowchart showing an example of opening / closing control of an electromagnetic valve during refrigerant recovery.
FIG. 5 is a schematic configuration diagram showing a heat pump automotive air conditioner according to a fourth embodiment of the present invention.
FIG. 6 is a schematic configuration diagram showing an example of a conventional heat pump automobile air conditioner.
FIG. 7 is a diagram for explaining a state of a sleeping refrigerant in a main capacitor.
[Explanation of symbols]
4 ... Evaporator (indoor evaporator),
5 ... Sub capacitor (indoor capacitor),
6 ... Compressor,
7 ... Main capacitor (outdoor capacitor),
9 ... expansion valve (pressure reduction means),
12 ... Refrigerant piping,
13 ... Bypass pipe,
20 ... Three-way valve (refrigerant flow path switching means),
30. Refrigerant recovery pipe,
31 ... Solenoid valve (opening / closing means),
32. Check valve,
33, 34 ... Solenoid valves (refrigerant flow path switching means).

Claims (4)

A compressor (6), an outdoor condenser (7), an indoor condenser (5), a pressure reducing means (9), and an indoor evaporator (4) are connected in this order by a refrigerant pipe (12) and discharged from the compressor (6). The bypass pipe (13) for bypassing the outdoor condenser (7) to the indoor condenser (5) and the refrigerant discharged from the compressor (6) on the outdoor condenser (7) side during cooling operation In the heating operation, the refrigerant flow switching means (20) leading to the bypass pipe (13) side and the refrigerant staying in the outdoor condenser (7) are returned to the suction side of the compressor (6). In a heat pump type automotive air conditioner comprising a refrigerant recovery pipe (30),
The refrigerant recovery pipe (30) is connected between the outlet side of the outdoor condenser (7) and the suction side of the compressor (6),
Opening and closing means (31) for opening and closing the refrigerant recovery pipe (30),
The refrigerant flow switching means includes a first electromagnetic valve (33) provided in an inlet pipe of the outdoor condenser (7) and a second electromagnetic valve (34) provided in the bypass pipe (13). ,
When the heating operation is selected, the compressor (6) is started with the first solenoid valve (33) opened, the second solenoid valve (34) closed, and the opening / closing means (31) opened. When the elapsed time after starting the compressor ( 6 ) is equal to or longer than the first predetermined time, the first solenoid valve (33) is closed and the second solenoid valve (34) is opened, and the solenoid valve (33, 34) The air conditioner for a heat pump type automobile, wherein the opening / closing means (31) is closed when the elapsed time after switching becomes a second predetermined time or more. A compressor (6), an outdoor condenser (7), an indoor condenser (5), a pressure reducing means (9), and an indoor evaporator (4) are connected in this order by a refrigerant pipe (12) and discharged from the compressor (6). The bypass pipe (13) for bypassing the outdoor condenser (7) to the indoor condenser (5) and the refrigerant discharged from the compressor (6) on the outdoor condenser (7) side during cooling operation In the heating operation, the refrigerant flow switching means (20) leading to the bypass pipe (13) side and the refrigerant staying in the outdoor condenser (7) are returned to the suction side of the compressor (6). In a heat pump type automotive air conditioner comprising a refrigerant recovery pipe (30),
The refrigerant recovery pipe (30) is connected between the outlet side of the outdoor condenser (7) and the suction side of the compressor (6),
Opening and closing means (31) for opening and closing the refrigerant recovery pipe (30),
When the heating operation is selected, the compressor (6) is started in a state where a cooling cycle is formed by the refrigerant flow switching means (20) and the opening / closing means (31) is opened , and the compressor ( 6 ) When the elapsed time after activation becomes equal to or longer than the first predetermined time, the refrigerant flow switching means (20) switches to the heating cycle, and when the elapsed time after switching the refrigeration cycle becomes equal to or longer than the second predetermined time, A heat pump type automotive air conditioner characterized in that the opening and closing means (31) is closed.   The open / close means (31) is a pilot differential pressure actuated solenoid valve (31a) provided in the refrigerant recovery pipe (30) in a positive direction with respect to a refrigerant recovery direction. 2. A heat pump type automobile air conditioner according to 2.   The check valve (32) for backflow prevention is provided in the refrigerant recovery direction downstream side of the pilot differential pressure operation type solenoid valve (31a) of the refrigerant recovery pipe (30). The heat pump type automotive air conditioner described.

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