JPH026214A - Air conditioner for automobile - Google Patents

Abstract

PURPOSE:To carry out the cooling operation with an evaporator under the full refrigerant state and improve the cooling ability of the evaporator by detecting the level of an accumulator and controlling the opening degree of an expansion valve so that the evaporator is filled with a liquid refrigerant. CONSTITUTION:When the operation is started with an expansion valve 4 being full-opened and the air temperature is lowered, the refrigerant amount in an accumulator 8 is increased, and a float 44 is raised to increase the resistance value. Thus, an electric current corresponding to the resistance value is inputted as a level signal of the liquid refrigerant to an amplifier 21, where the level signal is compared with the st temperature corresponding signal of a controller. When the level signal is smaller or in accord, the refrigerant amount within the evaporator 5 is less or optimal, so that the amplifier 21 continues the full- opening of the valve 4 without operating a stepping motor M, but when the level signal is larger, the refrigerant is excessive. Thus, when the liquid refrigerant is stored in a determined amount within the accumulator 8, the evaporator 5 is started to operate in the state filled with the refrigerant, and the air is cooled by the whole evaporator to improve the heat exchanging efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an air conditioner for an automobile that improves the performance of an evaporator.

(Prior Art) In general, air conditioners for automobiles are
, No. 352, the CCEV method (Cycle
ing clutch expansion-valv
It has a cooling cycle called e system.

As shown in FIG. 4, in this cooling cycle, refrigerant discharged from a compressor 1 is condensed in a condenser 2, separated into gas and liquid in a liquid tank 3, and then transferred to an expansion valve 4, which is the refrigerant expansion member. The fat is adiabatically expanded and introduced into the evaporator 5, and after being evaporated, it is returned to the compressor 1.

In this type of cooling cycle, the state of the refrigerant at the outlet of the evaporator 5 is normally detected by the exothermic cylinder 6 to adjust the opening degree of the expansion valve 4. The plant is operated under control so that the heat amount (heat amount) is approximately 5°C.

That is, the liquid refrigerant returns to the compressor 1, and all the refrigerant flowing out from the evaporator 5 becomes vaporized gas refrigerant so that problems such as liquid compression do not occur.

Therefore, when the evaporator is operated in a state where the entire evaporator is filled with liquid refrigerant (hereinafter referred to as "full liquid" for simplicity), a large cooling capacity is exhibited. According to experiments, it has been found that when operated in the liquid-filled mode, cooling capacity is increased by about 5 to 10%.

(Problem to be Solved by the Invention) However, when the cooling operation is performed with the liquid full, the refrigerant flowing out from the outlet side of the evaporator is also a liquid refrigerant, so the amount of superheat is zero, and the CCE
In the case of the V type in which the opening degree of the expansion valve is controlled by detecting the amount of superheat, there is a problem that the expansion valve 4 cannot be used substantially.

In addition to the above-mentioned CCEV system, the cooling cycle also includes C
C0T method (Cycling clutch or
There is something called the IFICE-TUBU system.

As shown in FIG. 5, in this cooling cycle, refrigerant discharged from a compressor 1 is condensed in a condenser 2, the flow rate is controlled by an orifice tube 7, which is the refrigerant expansion member, and then guided to an evaporator 5. A part of the refrigerant is stored in an accumulator 8, and only the gas refrigerant is returned to the compressor 1.

This CC0T type automobile air conditioner is set to operate in the above-mentioned flooded system, so it has good thermal efficiency as mentioned above, but since the opening degree of the orifice 7 is fixed, this is not possible. It is not possible to control the refrigerant flow rate by

For example, if the amount of refrigerant in this cooling cycle is set to the amount required during rapid cooling (cool down), there will be an excess of refrigerant during normal cooling operation, and the amount of refrigerant will be reduced during normal cooling operation. If the amount of refrigerant is determined, there is a drawback that desired cooling cannot be performed during the cool-down. In other words, there is a drawback in that it is not possible to perform a detailed cooling operation that corresponds to the condition of the outside air. Also,
In this type of automotive air conditioning system, even when the cooling cycle is turned off, the refrigerant continues to flow through the circuit until the circuit reaches equilibrium, so there is a problem in that refrigerant flow noise occurs even after the automotive air conditioning system is stopped. .

In this way, there are various problems when trying to improve cooling performance, but especially when a stacked evaporator is used as the evaporator, a partition plate is installed inside the stacked evaporator to control the flow of refrigerant. The cooling capacity is improved by forcing the change so that the refrigerant flows inside the evaporator while repeatedly making U-turns.

However, this method has disadvantages in that flow path resistance increases, refrigerant flow noise occurs, and refrigerant does not flow smoothly, and the reality is that improvements are desired.

The present invention has been made in order to solve the drawbacks and problems associated with the prior art described above, and it is possible to perform efficient cooling operation using a liquid-filled system, and also to control the amount of refrigerant using an expansion valve, thereby providing fine-grained cooling. Not only does it enable cooling operation, but also
An object of the present invention is to provide an air conditioner for an automobile with low refrigerant noise and flow path resistance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention condenses refrigerant discharged from a compressor in a condenser, guides it to an evaporator via an expansion valve, and stores it in an accumulator. In the automobile air conditioner, the liquid level in the accumulator is detected and the opening degree of the expansion valve is controlled so that the inside of the evaporator is filled with liquid and cooled. This is a characteristic feature.

(Function) In this way, the opening degree of the expansion valve can be adjusted according to the liquid level state of the liquid refrigerant present in the accumulator, and cooling operation can be performed with the evaporator always full of liquid. Cooling capacity can be improved by maximizing the capacity.Also, since the refrigerant can flow into the evaporator all at once, there is no need to partition the inside of the evaporator with partition plates, reducing passage resistance and refrigerant. This enables operation with less flow noise.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic explanatory diagram according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional explanatory diagram showing the main parts of the embodiment shown in FIG. 1, and the members shown in FIG. 4.5. The same members are given the same reference numerals.

This automotive air conditioner 20 is almost the same as the CCEV type cooling cycle described above, and the refrigerant discharged from the compressor 1 is condensed in the condenser 2, and the liquid tank 3 performs gas-liquid separation and removal of dust, etc. After this, the flow rate of this refrigerant is adjusted by an electronic automatic expansion valve 4 and guided to an evaporator 5, liquid refrigerant is stored in an accumulator 8, and only the gas refrigerant in this accumulator 8 is returned to the compressor 1. Particularly, in this embodiment, the liquid level of the liquid refrigerant in the accumulator 8 is sensed, a position detection signal corresponding to this liquid level is inputted to the amplifier 21, and the opening degree of the expansion valve 4 is adjusted from this amplifier 21. A drive signal is output to the stepping motor M that performs the operation.

More specifically, as shown in FIG. 2, the expansion valve 4 is housed in a casing 24 that has a refrigerant port 22 communicating with the liquid tank 3 side and a refrigerant outlet 23 communicating with the evaporator 5 side. A communication passage 25 is formed, a valve seat 26 is provided in the middle of the communication passage 25, and an opening 27 formed in the valve seat 26 is adjusted by a valve body 29 provided on a valve stem 28. ing. The valve stem 28 acts as a rotating shaft of the stepping motor M at its upper portion, and a magnet 30 is disposed around it, forming a rotor R that is rotatable around the shaft. Magnet 30 in this rotor R
A stator coil 31 is fixed in the casing 24 around the stator coil 31, and an appropriate current is passed through the stator coil 31 to generate a rotating magnetic field, thereby rotating the rotor R at an appropriate rotation angle. Further, a male thread 32 is cut approximately at the center of the valve stem 28 in this rotor R, and this male thread 32 is screwed into a female thread 34 formed on a valve stem holding plate 33 fixed to the casing 24. It has become.

Therefore, by appropriately rotating the rotor R of the stepping motor M, the valve stem 28 can be moved to the valve stem holding plate 3.
3, that is, the opening degree of the opening 27 provided in the valve seat 26 is adjusted by moving it up and down with respect to the casing 24.

Further, a stop pin 35 is fixed to the lower part of the male thread 32 formed on the valve stem 28, so that it rotates together with the valve stem 28. This stop pin 35 is fixed to the valve stem 2 against the stopper member 36 fixed to the valve stem holding plate 33.
8, the rotation of the valve stem 28 is restricted. This is because when the valve body 29 provided at the tip of the valve body 28 moves to the lowest position and contacts the valve seat 26 to close the opening 27, the valve stem 28 rotates further and the valve body 29 moves downward. This is to prevent so-called galling from occurring between the valve body 29 and the valve seat 26 due to downward movement (overstroke).

On the other hand, the gauging 40 of the accumulator 8 is provided with an inlet pipe 41 into which the liquid refrigerant from the evaporator 5 flows, and an outlet pipe 42 that returns the gas refrigerant in the casing 40 to the compressor 1 side. is suspended to the vicinity of the bottom inside the casing 40, and a liquid level position detection means 43 for detecting the liquid level of the liquid refrigerant is provided on its outer periphery.

The liquid level position detecting means 43 includes a float 44 that is fitted onto the outer periphery of the inlet pipe 41 and moves up and down as the liquid level rises and falls.
It consists of a contactor 45 attached to the inner peripheral surface of a through hole 44a opened at the center of the float 44, and a resistance member 46 attached to the outer periphery of the inlet pipe 41, which resists the rise and fall of the float 44. Accordingly, the resistance value of the resistance member 46 changes.

Thereby, a current corresponding to the liquid level is inputted to the amplifier 21 as a liquid level position detection signal.

That is, as shown in FIG. 3, when the resistance value reaches 0, a signal indicating refrigerant shortage is output, and the expansion valve 4 is fully opened. If this fully open state continues, the amount of refrigerant will increase, and the amount of liquid refrigerant in the accumulator 8 will increase. As the amount of liquid refrigerant increases, the refrigerant returned from the evaporator 5 to the accumulator 8 becomes liquid refrigerant, and therefore full liquid operation begins. In this case, the temperature of the air blown out from the evaporator 5 or the temperature of the outside air is compared with the set temperature of the controller, and the resistance is detected so that a predetermined amount of refrigerant flows into the evaporator 5. output as a refrigerant flow control signal.

In addition, when the heat load is small, there will be an excess of refrigerant, so it is necessary to reduce the amount of refrigerant even in full liquid operation, so a signal is output to limit the refrigerant flow rate when the resistance exceeds a predetermined resistance value. do. Thereby, the opening degree of the expansion valve 4 is controlled so that the evaporator 5 always operates normally with full liquid.

Next, the action will be explained.

The amount of refrigerant required during normal operation is injected into the cooling cycle. Then, when the compressor 1 is started, this refrigerant is condensed in the condenser 2, separated into gas and liquid in the liquid tank 3, and dust and the like are removed, and most of the refrigerant is turned into liquid refrigerant and flows into the expansion valve 4.

Since a large amount of refrigerant is normally required at the beginning of startup, the expansion valve 4 is kept almost fully open. This refrigerant evaporates in the evaporator 5, removes heat from the air, flows into the accumulator 8, is stored, and only the gas refrigerant is returned to the compressor 1.

Even after performing the cooling operation, if the air is still at a high temperature and the load is large, it is necessary to increase the opening degree of the expansion valve 4 and further increase the amount of refrigerant in the evaporator 5. Due to this increase in the amount of refrigerant, there is less liquid refrigerant in the accumulator 8, a current with a resistance value of 0 is input to the amplifier 21, and the expansion valve 4 continues to be fully open.

As this operation continues and the air temperature decreases, the amount of refrigerant in the accumulator 8 gradually increases, and the float 4
4 increases, and the resistance value increases. Therefore, the current corresponding to the resistance value is input to the amplifier 21 as a liquid refrigerant level signal, and the amplifier 21 compares the liquid level signal with a signal corresponding to the temperature set by a controller (not shown). If the liquid level signal is smaller than or equal to the signal corresponding to the set temperature, the amount of refrigerant in the evaporator 5 is small or optimal;
If the amplifier 21 does not operate the stepping motor M and keeps the expansion valve 4 fully open, and if the liquid level signal becomes larger than the signal corresponding to the set temperature, there will be an excess of refrigerant.

In this case, when a predetermined amount of liquid refrigerant is stored in the accumulator 8, a full liquid operation in which the evaporator 5 is filled with liquid refrigerant is started, and the air is cooled throughout the evaporator 5, increasing the heat exchange efficiency. It will cool the air well.

Even during this full liquid operation, if the refrigerant in the accumulator 8 increases and the liquid level signal becomes larger than the signal corresponding to the set temperature, it is necessary to limit the amount of refrigerant to the evaporator 5, so in this case, The amplifier 21 operates the stepping motor M to rotate the valve rod 28 and move it in a direction to close the opening 27 of the valve seat 26. As a result, the amount of refrigerant decreases, and the evaporator 5 continues to operate full of liquid.
The amount of refrigerant is controlled by the controller to match the selected temperature.

Furthermore, when the temperature of the air decreases and the amount of liquid refrigerant in the accumulator 8 increases, the resistance value further increases and approaches the maximum, but in this case, the liquid level signal reaches the set temperature. If the resistance value is smaller than the corresponding signal, the cooling operation is continued; however, if the resistance value is larger than the predetermined value, the cooling operation is no longer required. A signal is output to rotate the stepping motor M, and the expansion valve 4 is closed.

[Effects of the Invention] As described above, according to the present invention, the liquid level of the accumulator is detected and the opening degree of the expansion valve is controlled so that the inside of the evaporator is filled with liquid refrigerant. The evaporator can perform cooling operation in a full liquid state, and the ability of the evaporator can be maximized. As a result, the cooling ability of the evaporator can be improved. In addition, since it is a full liquid type, the refrigerant flow rate inside the evaporator does not increase unnecessarily, and the refrigerant inside the evaporator can flow at a slow speed that does not cause passage resistance. There will be no noise. Furthermore, in order to obtain a predetermined cooling capacity, the size of the evaporator can be made smaller than that of conventional ones, and this makes it possible to downsize the air conditioner for automobiles.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional explanatory diagram showing the main part of the embodiment shown in FIG. 1, and FIG. 3 is a diagram showing a liquid level signal and an evaporator. Fig. 4 is an explanatory diagram comparing the state of the refrigerant in the vehicle.
The figure is an explanatory diagram showing a cooling cycle of a conventional CCOT type automobile air conditioner. 1... Compressor, 4... Expansion valve, 8... Accumulator. 2... Capacitor, 5... Evaporator,

Claims (1)

[Claims] 1) Refrigerant discharged from the compressor (1) is condensed in the condenser (2), guided to the evaporator (5) via the expansion valve (4), stored in the accumulator (8), and then returned to the compressor (1). In the automotive air conditioner, the opening degree of the expansion valve (4) is controlled by detecting the liquid level of the accumulator (8) so that the inside of the evaporator (5) is filled with liquid. An air conditioner for an automobile characterized by the following.