JPH0531065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heat pump type room air conditioner, and particularly to a heat pump type room air conditioner that is intended to shorten the start-up time during a cold start of heating operation.

[Background of the invention]

First, a conventional heat pump type room air conditioner (Japanese Patent Laid-Open No. 58-214755) will be explained.

FIG. 2 is a cycle configuration diagram of a conventional heat pump type room air conditioner. In this Figure 2, 1 is a compressor, 2 is a four-way switching valve that controls the flow direction of the refrigerant, 3 is an indoor heat exchanger, and 4 is an electric expansion valve (for controlling this electric expansion valve 4). The structure will be described later), and 5 is an outdoor heat exchanger.

In the heat pump type room air conditioner configured as described above, during heating operation, the high-temperature, high-pressure refrigerant compressed by the compressor 1 is sent to the indoor heat exchanger 3 by the four-way switching valve 2;
It radiates heat, condenses, and becomes a high-pressure liquid refrigerant. Next, this liquid refrigerant is depressurized by the electric expansion valve 4 to become a low-temperature, low-pressure refrigerant, after which it absorbs heat and evaporates in the outdoor heat exchanger 5, and returns to the compressor 1 from the four-way switching valve 2, repeating the cycle.

A configuration for controlling the electric expansion valve 4;
The control method will be explained next.

In FIG. 2, 6 is a first temperature detector that detects the refrigerant temperature at the inlet of the outdoor heat exchanger 5;
This is a second temperature detector that detects the temperature of the absorbed refrigerant of the compressor 1. 8 is the first and second temperature detector 6,
This is a motor controller that compares signals from 7 and controls a motor driver 10 that drives a pulse motor 9 that opens and closes an electric expansion valve 4 according to the difference.

The electric expansion valve 4 uses a pulse motor to open and close the valve part (not shown), whereas a conventionally used temperature-sensitive expansion valve (not shown) uses a diaphragm (not shown) to open and close the valve part (not shown). This valve converts the rotational force of 9 into vertical movement using a screw to open and close the valve part. Therefore, a pulse motor that can control the rotational force with high accuracy is generally used as the motor that provides the rotational force for opening and closing.

The motor controller 8 has a function of receiving an external signal (first and second temperature detectors 6 and 7 in FIG. 2) and generating a pulse signal that rotates the pulse motor 9 in a predetermined direction by a predetermined angle. This is a device with Further, the motor driver 10 amplifies the pulse signal output from the motor controller 8 and drives the pulse motor 9.

Note that a device in which the pulse motor 9 and the electric expansion valve 4 are integrated is also commercially available.

Next, the operation of controlling the electric expansion valve 4 will be explained.

During steady heating operation, when the heat exchange capacity of the outdoor heat exchanger 5 decreases due to a drop in outside air temperature, etc., the liquid refrigerant that has not been completely evaporated in the outdoor heat exchanger 5 begins to return to the compressor 1. In a two-phase refrigerant, if the pressure is constant, the temperature is also constant.
In such a state, the inlet temperature of the outdoor heat exchanger 5 and the suction temperature of the compressor 1 become equal. At this time, the motor controller 8 which has received the information that the temperatures are equal from the first and second temperature detectors 6 and 7 sends a signal to the motor driver 10 to drive the pulse motor 9 and operate the electric expansion valve 4. Control in the closing direction.
As the electric expansion valve 4 closes, the evaporation pressure decreases and the evaporation temperature decreases, so that sufficient evaporation occurs in the outdoor heat exchanger 5, and conversely, the refrigerant that returns to the compressor 1 decreases. It's getting super heated. In such a state, the suction temperature of the compressor 1 is higher than the inlet temperature of the outdoor heat exchanger 5, so a difference occurs between the temperature signals from the first and second temperature detectors 6 and 7. This difference is compared with a preset value set in the motor controller 8, and if the difference is larger, the motor controller 8 sends a signal to the motor driver 10 to drive the pulse motor 9 in the opposite direction. ,
The electric expansion valve 4 is controlled in the opening direction. In this way, the electric expansion valve 4 is controlled so that the difference between the temperature signals of the first and second temperature detectors 6 and 7 is equal to the set value. Since there is a delay in the response of 5, it diverges and effective control is not possible, so PID control is usually used in addition to integral control and differential control.

The control of the electric expansion valve 4 according to the conventional technology has been described above, but basically it is a feedback control that detects the degree of superheat of the refrigerant sucked into the compressor 1 and controls the electric expansion valve 4 based on that value. , unable to respond to rapid changes. Therefore,
In conventional heat pump type room air conditioners, liquid compression occurs when the heating/cooling operation starts (when the refrigeration cycle starts operating from a completely cold state after a long period of time has passed since the previous operation ended). There was a problem that the rising speed was slow and it took a long time to bring the room temperature to the set value (comfortable temperature).

The reason why such a problem occurs will be explained below.

Usually, in a heat pump room air conditioner, everything except the indoor heat exchanger 3 is located outside the room. When the operation is stopped, all parts of the refrigeration cycle, both indoors and outdoors, have the same pressure. However, the lower the temperature, the more condensed the refrigerant is, so it is We will get together.

During the winter when heating operation is performed, the outdoor temperature is lower than the indoor temperature, and during the heating operation, the temperature of the outdoor heat exchanger 5 is lower than that of the indoor heat exchanger 3. Therefore, when the pressure inside and outside of the refrigeration cycle becomes the same when the operation is stopped, the refrigerant gathers in the low-temperature outdoor heat exchanger 5 with a low saturation pressure and remains as a liquid refrigerant. When heating operation is started in such a state, the liquid refrigerant in the outdoor heat exchanger 5 is
The liquid returns to the compressor 1 and is compressed without much evaporation, resulting in liquid compression that may lead to damage to the discharge valve (not shown) in the compressor 1. This occurs because the conventional electric expansion valve control method described above has a slow response and cannot prevent rapid liquid return. Furthermore, when such liquid return occurs, unevaporated liquid refrigerant is discharged to the discharge side of the compressor 1;
It serves as a high-pressure container (not shown) that houses a compression pump section and a motor section (both not shown) of the compressor 1, and liquid refrigerant is discharged into the high-pressure container. At this time, since the compressor 1 is located outdoors, the temperature is low at the start of operation, and the liquid refrigerant in the high-pressure container remains in the compressor 1 until the temperature of the compressor 1 rises, so the refrigeration cycle Overall, there will be a refrigerant shortage. In this state,
Since the refrigerant is not sufficiently distributed to the outdoor heat exchanger 5, it becomes significantly superheated and cannot effectively absorb heat from the outside air. However, in the conventional electric expansion valve control method described above, the inlet of the outdoor heat exchanger Since the difference between the refrigerant temperature and the suction refrigerant temperature of the compressor 1 is detected and the electric expansion valve 4 is gradually controlled based on the change, it is not possible to shorten the superheat time.

As described above, the conventional heat pump room air conditioner shown in FIG. 2, which is equipped with the above-mentioned electric expansion valve control means, causes liquid compression when starting heating/cooling, starts slowly, and does not reach a steady state during heating operation. There was an issue that needed improvement: it took a long time for the room temperature to reach the set value.

[Purpose of the invention]

The purpose of the present invention is to provide a heat pump type room air conditioner that eliminates the above-mentioned problems of the prior art, increases the start-up speed when starting heating/cooling, and can bring the room temperature to a comfortable temperature in a short time. It is something to do.

[Structure of the invention]

The configuration of the heat pump room air conditioner according to the present invention includes at least a compressor, an indoor heat exchanger,
A heat pump type which is provided with an electric thermal expansion valve and an outdoor heat exchanger connected in sequence, and is equipped with a motor driver capable of opening and closing the electric expansion valve, and a motor controller that utilizes this motor driver. In room air conditioners, we use sequential controllers that can sequentially control electric expansion valves.
A heating/cooling start detector that is connected to the motor driver and detects a heating/cooling start state is provided connected to the sequential controller and the motor controller, and the sequential controller and the heating/cooling start detector are connected to the sequential controller and the motor controller. Accordingly, at the time of heating/cooling startup, the electric expansion valve is closed by the motor driver for a predetermined short time while driving the compressor, and then for the next predetermined time,
Sequential operation in which the electric expansion valve is opened by the motor driver and then closed at a preset rate during a predetermined period of time until the electric expansion valve reaches a preset opening degree. It is configured to perform control.

That is, the heat pump type room air conditioner of the present invention is equipped with a heating/cooling start detector capable of detecting the state of heating/cooling start, and a sequential controller that sequentially controls an electric expansion valve. A detector detects the state of heating/cooling activation, and the sequential controller controls the electric expansion valve according to the degree of detection. Therefore, the control of the electric expansion valve is sequential control at startup, and the time for performing this sequential control is determined by the degree of cold startup at startup.

[Action of the invention]

The details of the sequential control of the electric expansion valve are as follows.

Fully close the electric expansion valve before starting the compressor. This is to reduce the rapid return of liquid at the time of heating/cooling startup, thereby making it possible to prevent damage to the discharge valve due to liquid compression and to increase the amount of heat absorbed by the outdoor heat exchanger. Although it is assumed here that the electric expansion valve is fully closed, this is based on the control signal, and actual electric expansion valves are usually manufactured so as not to be completely closed. The reason for this is
This is to prevent further pressure rise by allowing a small amount of refrigerant to flow even if the compressor were to move while the electric expansion valve was completely closed and stopped.

Although the electric expansion valve does not close completely even if it receives a full-close signal, the above-mentioned liquid compression does not occur even if a small amount of refrigerant flows, so the effect of the present invention is not affected in any way. It doesn't hurt anything.

Next, after a certain period of time has elapsed, the electric expansion valve is fully opened. This is to make the superheat caused by a lack of refrigerant that occurs during heating/cooling startup as short as possible.

After this fully open state continues for a predetermined period of time, the electric expansion valve is closed at a preset constant rate.
This is because if the compressor remains fully open for a long period of time, the discharge pressure of the compressor will rise slowly, which will actually delay the start-up of heating or cause liquid return to the compressor. The rate at which the electric expansion valve is closed is set such that the opening degree of the electric expansion valve reaches the set opening degree when the frozen lake is stabilized within a predetermined period of time. The sequential control time of such an electric expansion valve is determined by the state of heating/cooling startup before startup, and is set longer when the compressor is completely cold.

After the above sequential control, the control of the electric expansion valve shifts to normal control by the motor controller as explained in FIG. 2.

[Embodiments of the invention]

Examples will be explained below.

FIG. 1 is a cycle configuration diagram of a heat pump type room air conditioner according to an embodiment of the present invention, FIG. 3 is a configuration diagram of a control device for starting heating and cooling of the heat pump type room air conditioner according to FIG. 1, and FIG. 4 FIG. 4 is a time chart showing an example of the sequential operation of the electric expansion valve by the heating/cooling activation control device according to FIG. 3;

In FIG. 1, parts given the same reference numerals as in FIG. 2 are the same parts.

This heat pump type room air conditioner has a compressor 1, a four-way switching valve 2, an indoor heat exchanger 3, an electric expansion valve 4, an outdoor heat exchanger 5, and
As controllers for controlling the electrically operated expansion valve 4, a first temperature detector 6, a second temperature detector 7, and signals from the first temperature detector 6 and the second temperature detector 7 are used to control the electrically operated expansion valve 4. A motor controller 8 and a motor driver 10 control a pulse motor 9 that opens and closes the expansion valve 4, and a sequential controller 11, which will be described later, detects the state of heating/cooling startup and, at startup, does not go through the motor controller 8. A timer-type heating/cooling start detector 12 (details will be described later) selects a motor control signal corresponding to the state of heating/cooling start detected by the timer-type heating/cooling start detector 12.
0 and is equipped with a sequential controller 11 that controls the electric expansion valve 4. This sequential controller 11 is a device that has the function of generating a pulse signal that rotates the pulse motor 9 by a predetermined angle in a predetermined direction, similar to the motor controller 8 described in the explanation of the conventional heat pump type room air conditioner. be. The sequential controller 11 is different from the motor controller 8 in that the motor controller 8 receives external signals (in FIG. 1, the first and second temperature detectors 6,
7) and changes the generated pulse signal depending on the content, whereas the sequential controller 1
1 is that the pulse signal is output as programmed in advance. Therefore, the sequential controller 11 includes at least a timer, a pulse generator, a storage device, and a control device (none of which are shown) for controlling them.

The timer-type heating/cooling start detector 12 is connected to the sequential controller 11 and the motor controller 8, and measures the time elapsed since the end of the previous operation, and detects when the elapsed time is long. teeth,
Electric expansion valve 4 with sequential controller 11
The sequential control time can be lengthened, and when the elapsed time is short, the sequential control time can be shortened.

Next, using FIG. 3, a control device for starting heating and cooling of this heat pump type room air conditioner will be explained. In this FIG. 3, 13 is a microcomputer, 14 is a heating operation start switch that sends a signal to start heating operation to this microcomputer 13, 15 is a compressor relay for starting the compressor 1, and 6 to 12 are controllers for controlling the electric expansion valve 4 as described above.

Here, the microcomputer 13 is a device that controls a room air conditioner, and is generally provided with various functions. Here, only the functions related to the present invention will be explained.

The microcomputer 13 consists of at least an arithmetic section, a storage section, an input section, and an output section (none of which are shown), and performs calculations using a program prestored in the storage section based on signals input from the input section. , outputs instructions from the output section.

The operation of the heat pump room air conditioner constructed in this way will be explained.

When the heating operation start switch 14 is turned on, a heating operation start signal is input to the microcomputer 13. The microcomputer 13 has a timer type heating/cooling start detector 1 in response to the input signal.
2 and the compressor relay 15, the microcomputer 13 can be programmed to output signals to the timer type heating/cooling start detector 1.
A heating start signal is sent to compressor relay 15 and compressor relay 15 . Upon receiving the signal, the timer heating/cooling activation detector 12 first selects the sequential controller 11 without selecting the motor controller 8, and controls the electric expansion valve 4 by the sequential controller 11. On the other hand, the compressor 1 is driven by the compressor relay 15.

The timer type heating/cooling start detector 12 adjusts the time period during which control is performed by the sequential controller 11 according to the elapsed time since the end of the previous heating operation.
A specific example will be explained with reference to FIG. In FIG. 4, the upper diagram shows the opening degree P of the electric expansion valve,
The figure below shows the elapsed time T from the end of the previous operation.
shows. The horizontal axis in both the upper and lower diagrams is compressor 1.
This is the elapsed time since startup. Sequential control of the electric expansion valve 4 by the sequential controller 11 starts with the valve fully closed as shown in the above figure.

Keep this fully closed state for a certain period of time (usually about 0.5 to 1 minute)
After continuing, it suddenly becomes full throttle (P ₁ ). After this fully open state continues for a predetermined time, the electric expansion valve 4 is closed at a constant rate. This closing ratio is set so that the opening degree of the electric expansion valve 4 reaches the set opening degree of the electric expansion valve 4 when the refrigeration cycle is stabilized within a predetermined period of time.

The sequential control of the electric expansion valve 4 programmed in advance in this way is not executed from beginning to end in any case in the case of heating/cooling startup, but is executed based on the elapsed time from the end of the previous operation. Therefore, the sequential control time of the electric expansion valve 4 changes.

If the elapsed time from the end of the previous operation is _T1 , the time controlled by the sequential controller 11 is _t1 , and the opening degree of the electric expansion valve 4 is changed during this time.
It starts with front close and narrows down from the previous time (P ₁ ) to P ₂ and P ₃ .
The sequential control ends in state _P4 , and control is transferred to the motor controller 8.

In this way, no matter how short the elapsed time from the end of the previous operation, the electric expansion valve 4 is sequentially controlled and starts operating in a fully closed state. This is because, as mentioned above, when the heating operation ends, the refrigerant in the refrigeration cycle is transferred to the outdoor heat exchanger 5.
If the electric expansion valve 4 is open, a large amount of liquid will return when the electric expansion valve 4 is restarted, but if the electric expansion valve 4 is kept fully closed, the gas refrigerant from the indoor heat exchanger 3 will This is because the liquid refrigerant accumulated in the outdoor heat exchanger 5 is rapidly pushed out and does not return to the compressor 1, so that liquid return can be minimized. This fully closed state is followed by a fully open state in order to minimize the superheat caused by lack of refrigerant that occurs during heating/cooling startup. Immediately after startup, the refrigeration cycle almost always runs out of refrigerant, resulting in a significant superheat state. At this time, since the absorption pressure of the compressor 1 is abnormally low, the specific volume of the solvent sucked into the compressor increases, the amount of refrigerant circulated in the refrigeration cycle decreases, and the start-up is delayed. Therefore,
By fully opening the electric expansion valve 4 and increasing the suction pressure of the compressor 1 when the refrigerant remaining in the outdoor heat exchanger 5 is exhausted, the superheat time at startup can be shortened. Note that if the compressor 1 is kept fully open for a long time when the elapsed time T from the end of the previous operation is short (the temperature of the compressor 1 is high), the compressor 1
As the temperature is higher, there is less liquid refrigerant stagnation in the compressor 1, so the period of refrigerant shortage is short, and liquid return operation is started.As shown in Fig. 4, the progress from the end of the previous operation is The full opening time is controlled according to the time T.

In this case, the reason why the opening degree was sequentially reduced to P ₁ , P ₂ , etc. instead of remaining fully open (P ₁ ) is that even if the refrigeration cycle is started when it is completely cold, the electric expansion valve 4 is kept fully open. This is because if the compressor 1 continues to operate, the discharge pressure of the compressor 1 will rise slowly, which may even slow down the start-up of heating.

According to the embodiment described above, the elapsed time T from the end of the previous operation is measured, and the elapsed time T
If it is long, the sequential control time of the electric expansion valve 4 by the sequential controller 11 is lengthened, and if it is short, the sequential control time is shortened, and after this sequential control time has elapsed, as in the conventional case, Since it is controlled by the motor controller 8, it is possible to prevent the liquid from returning during heating/cooling startup, shorten the superheat time, increase the startup speed, and bring the room temperature to a comfortable temperature in a short time. effective.

FIG. 5 is a cycle configuration diagram of a heat pump type room air conditioner according to another embodiment of the present invention.
In FIG. 5, the same parts are denoted by the same reference numerals as in FIG. 1.

This heat pump room air conditioner has a compressor 1 instead of the timer heating/cooling start detector 12 in the heat pump room air conditioner shown in FIG.
A temperature-type heating/cooling start detector 17 is provided which is equipped with a compressor temperature detector 16 that detects the temperature of the compressor. The control time is lengthened, and when it is high, the sequential control time is shortened.

As mentioned above, there is a close relationship between the compressor temperature and the amount of refrigerant that stays in the compressor, and the higher the compressor temperature, the shorter the refrigerant shortage time. Therefore, detecting the compressor temperature and determining the time during which control is transferred to the sequential controller 11 (this embodiment) is a method of measuring and determining the elapsed time from the end of the previous operation (the method described above). It is more direct and accurate than the embodiment according to Figure 1).

According to the embodiment related to FIG. 5 described above,
This embodiment has the advantage that more accurate control is possible without being affected by the outside temperature, and the rise speed during cold startup can be made even faster than in the embodiment shown in FIG.

In each of the above embodiments, the motor controller 8, the sequential controller 11, and the heating/cooling start detector 12 or 17 for switching between these controllers 8, 11 have been described as separate parts from the microcomputer 13. The functions can be programmed or integrated into the computer 13.

Furthermore, in each of the above embodiments, in order to simplify the explanation, the explanation was limited to the time when the heating was started.
This can be similarly applied when starting the air conditioner.

However, the content of the sequential control in this case may be slightly changed since the compressor temperature is high during cooling operation even when the operation is stopped. In the sequential control according to the present invention, when the compressor is started, the electric expansion valve is fully closed to prevent sudden liquid return. There is no need to narrow it down.
In addition, when narrowing down sufficiently, it is possible to make the fully closed time shorter than that during heating operation. Furthermore, the full-open control following the full-close control may not be particularly performed for the following reasons.

This is because during cooling operation, the capacity of the evaporator in the room to be cooled is extremely high, and the refrigerant returning to the compressor is in a significantly superheated state. Therefore, even if the electric expansion valve is not fully opened, normal motor control is sufficient to bring the electric expansion valve into the open state. Of course, the effect is the same even if the heating operation is fully opened using sequential control, as in the case of heating operation.

In the above embodiment, the electrically operated expansion valve is described as fully closed and fully open, but as mentioned above, even if the electrically operated expansion valve cannot completely shut off the flow of refrigerant, it can still be sufficiently throttled. It goes without saying that there is no problem even if there is a slight flow of refrigerant, since this does not impair the effects of the present invention. In addition, even when fully open, the electric expansion valve can only open so much.
Needless to say, even if the opening is not 100%, the effect of the present invention can be achieved as long as the opening is sufficiently wide, and therefore it is within the scope of the present invention.

〔Effect of the invention〕

As described above in detail, according to the present invention, it is possible to provide a heat pump type room air conditioner that can increase the startup speed at the time of starting heating/cooling and can bring the room temperature to a comfortable temperature in a short time.

[Brief explanation of the drawing]

FIG. 1 is a cycle configuration diagram of a heat pump type room air conditioner according to an embodiment of the present invention, FIG. 2 is a cycle configuration diagram of a conventional heat pump type room air conditioner, and FIG. 3 is a heat pump type room air conditioner according to FIG. 1. FIG. 4 is a configuration diagram of the control device for starting heating and cooling of a room air conditioner, and FIG. 4 is a time chart showing an example of sequential control of the electric expansion valve by the control device for starting heating and cooling according to FIG. 3. FIG. FIG. 2 is a cycle configuration diagram of a heat pump room air conditioner according to another embodiment of the present invention. 1...Compressor, 3...Indoor heat exchanger, 4...
Electric expansion valve, 5... Outdoor heat exchanger, 8... Motor controller, 10... Motor driver, 11... Sequential controller, 12... Timer type heating/cooling start detector, 16... Compression Machine temperature detector, 17...
Temperature type heating/cooling start detector, T...Elapsed time from the end of the previous operation.

Claims (1)

[Claims] 1. At least a compressor, an indoor heat exchanger, an electric expansion valve, and an outdoor heat exchanger are connected in sequence,
In a heat pump room air conditioner comprising a motor driver capable of opening and closing the electric expansion valve, and a motor controller controlling the motor driver, a sequential controller capable of sequentially controlling the electric expansion valve. is connected to the motor driver, and a heating/cooling start detector for detecting a state of heating/cooling start is provided connected to the sequential controller and the motor controller, and a heating/cooling start detector is connected to the sequential controller and the heating/cooling start detection. At the time of heating/cooling startup, the motor driver closes the electric expansion valve for a predetermined short time while driving the compressor, and then the motor driver closes the electric expansion valve for the next predetermined time. It is characterized by being configured to perform sequential control in which the electric expansion valve is opened and then closed at a preset rate during a predetermined period of time until the electric expansion valve reaches a preset opening degree. A heat pump type room air conditioner. 2. The heating/cooling start detector shall have the function of detecting the state of heating/cooling start and, depending on this state, determining the time for sequential control of the electric expansion valve by the sequential controller; When the detector determines that either the compressor temperature or the outdoor heat exchanger temperature is low, the sequential control time is set longer and the heating/cooling start detector determines that either the compressor temperature or the outdoor heat exchanger temperature is low. The heat pump room air conditioner according to claim 1, wherein when it is determined that one of the exchanger temperatures is not low, the sequential control time is set short to perform sequential control. 3. Use the heating/cooling start detector to measure the elapsed time since the end of the previous operation.
If the elapsed time is long, the sequential control time of the electric expansion valve by the sequential controller is lengthened, and if the elapsed time is short, the sequential control time is shortened. A heat pump type room air conditioner according to claim 2, characterized in that the heat pump type room air conditioner is a detector. 4. The heating/cooling start detector is equipped with a compressor temperature detector that detects the temperature of the compressor, and when the detected temperature is low, the sequential control time of the electric expansion valve by the sequential controller is lengthened, and the 3. The heat pump type room air conditioner according to claim 2, further comprising a temperature type heating/cooling activation detector configured to shorten the sequential control time when the detected temperature is high.