JPH04344080A - Gas heat pump air conditioner - Google Patents

Abstract

PURPOSE:To perform a suitable room cooling irrespective of atmospheric temperature and a pressure loss of an indoor unit by providing a temperature sensor for measuring a refrigerant temperature in an outlet/inlet of an indoor heat exchanger, and so controlling as to increase or decrease a rotating speed of an engine based on the output of the sensor. CONSTITUTION:In a gas heat pump air conditioner having a heat pump circuit in which a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, a receiver tank 5, an expansion valve at the time of room heating, an indoor heat exchanger 7 and an accumulator 8 are sequentially coupled, and the compressor 2 is driven by an engine 1, temperature sensors are respectively provided in the refrigerant inlet and outlet of the exchanger 7, and output signals of the sensors are input to a controller 9. A target temperature range for so controlling a temperature of the refrigerant is previously set in the controller 9 that a temperature of blow-off chilled gas falls within a predetermined temperature range. Then, the rotating speed of the engine is so controlled to be increased or decreased based on the real refrigerant temperature as to fall within the target temperature range.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas heat pump air conditioner.

0002

[Prior Art] A conventional gas heat pump air conditioner consists of an engine such as a gas or gasoline engine, a heat pump circuit that sequentially connects a compressor driven by the engine, an outdoor heat exchanger, a pressure reducer, and an indoor heat exchanger, and the engine. It is equipped with a rotation speed control device (hereinafter referred to as a control device) that controls the rotation speed of the engine.

[0003]This control device detects the engine rotational speed using the total operating horsepower (capacity) of one or more indoor units that blow out cold or warm air and a temperature sensor provided separately. It is determined based on the difference between the indoor temperature set by the controller and the set temperature set by the remote controller (hereinafter referred to as remote controller temperature difference).

[0004] The engine rotational speed relative to the total operating horsepower of the indoor unit changes in response to changes in the remote control temperature difference, as shown in FIG. That is, as the remote control temperature difference increases or decreases, the engine speed also increases or decreases within a range corresponding to the total operating horsepower of the indoor unit. For example, if the total operating horsepower of the indoor unit is 15PS, the engine speed will be 1333rpm to 1600rpm.
varies between pm.

[0005] Here, the engine reaches its minimum rotation speed when the remote control temperature difference is the minimum, which is 0 degrees, and the engine reaches its maximum revolution speed when the remote control temperature difference is maximum, for example. This is the case of 3rd degree. Note that even if the remote control temperature difference exceeds the maximum value of 3 degrees, the engine will rotate at the rotation speed at 3 degrees.

[0006]

However, in the conventional gas heat pump air conditioner, the rotational speed of the engine changes in response to the remote control temperature difference in this way, but this change is unrelated to the outside temperature.

[0007] Therefore, when performing cooling operation, if the remote control temperature difference is set to 3 degrees when the outside temperature is low, the engine will rotate at 1600 rpm regardless of the outside temperature, so it will become too cold and cause dew formation etc. Occur. Also, if you set the remote control temperature difference to 0 degrees when the outside temperature is high, the engine will rotate at 1333 rpm regardless of the outside temperature.
The cooling effect will not improve.

[0008] As described above, the conventional control device can cope with changes in the indoor temperature, but cannot cope with large changes in the outside temperature, and therefore has the problem of not being able to perform appropriate cooling.

Furthermore, when using multiple indoor units for cooling, even if indoor units with the same operating horsepower are used,
If the pressure loss between the indoor unit and the outdoor unit (hereinafter referred to as pressure loss of the indoor unit) is different, the flow rate of the refrigerant will be different, and the cooling effect will also be different. As a result, there is a problem in that one indoor unit may become too cold, and another indoor unit may hardly be cooled, even if the engine speed is the same.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas heat pump air conditioner that can perform appropriate cooling regardless of the outside temperature and the pressure loss of the indoor unit.

[0011]

[Means for Solving the Problems] The present invention provides an engine,
A heat pump circuit that sequentially connects a compressor, an outdoor heat exchanger, a pressure reducer, and an indoor heat exchanger driven by this engine,
In the gas heat pump air conditioner equipped with a rotation speed control device that controls the rotation speed of the engine, a temperature sensor is provided at the entrance and exit of the indoor heat exchanger to measure the refrigerant temperature,
The engine speed control device is configured to increase or decrease the engine speed based on temperature information from the temperature sensor.

0012

[Operation] In the present invention, the rotational speed control device can increase or decrease the rotational speed of the engine based on temperature information from a temperature sensor that measures the temperature of the refrigerant provided at the entrance and exit of the indoor heat exchanger.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings.

FIG. 1 is a circuit diagram of a gas heat pump air conditioner according to an embodiment of the present invention.

In the figure, 1 is an engine, 2 is a compressor driven by this engine 1, 3 is a four-way valve that switches the refrigerant flow path depending on cooling or heating, 4 is an outdoor heat exchanger,
5 is a receiver tank, 6 is an expansion valve (pressure reducer) during cooling,
7 is an indoor heat exchanger, and 8 is an accumulator provided on the suction side of the compressor 2. Further, 11 is an expansion valve during heating.

Furthermore, temperature sensors (not shown) using thermistors are provided at the refrigerant inlet and refrigerant outlet of the indoor heat exchanger 7, respectively. Reference numeral 9 denotes a control device composed of a microcomputer or the like to control the rotation speed of the engine 1. This control device 9 calculates the refrigerant inlet/outlet temperature of the indoor heat exchanger 7 of each indoor unit as measured by a temperature sensor, and increases/decreases the rotation speed of the engine 1 based on the result of this calculation.

In the figure, the broken lines indicate temperature information from the temperature sensor and the rotational speed control signal of the engine 1 from the control device 9, and the arrows indicate the flow of refrigerant.

Next, a description will be given of the engine rotational speed control operation during cooling of the gas heat pump air conditioner configured as described above.

When cooling is performed using a plurality of indoor units, first the remote control temperature difference a is set in accordance with the desired room temperature. Note that in an indoor unit with a large pressure loss, the amount of refrigerant flowing into the indoor heat exchanger 7 is smaller than that of an indoor unit without such a large pressure loss, so the outlet temperature of the refrigerant also becomes high, and the cooling effect does not increase much.

Next, the control device 9 controls the temperature of the refrigerant flowing into the indoor heat exchanger 7 so that the temperature of the cold air blown out from inside the indoor unit is within a temperature range that is neither too low nor too high. The target heat exchanger temperature, which is a target value for controlling the temperature, is set, for example, in the range of (8-a to 13-a)°C.

[0021] Based on the set target heat exchanger temperature, the control device 9 increases or decreases the engine speed so that the temperature of the refrigerant flowing into the indoor heat exchanger 7 falls within this temperature range. The reason why there is a range in the target heat exchanger temperature is because the temperature of the refrigerant at the entrance and exit of the indoor heat exchanger 7 differs depending on the pressure loss state of each indoor unit even if the engine speed is the same. be.

[0022] Here, the operation of increasing and decreasing the engine speed by the control device will be explained.

[0023] When performing a cooling operation using one or more indoor units in an operation category different from the operation category of the indoor unit in the previous cooling operation, the control device controls the target heat exchanger of the indoor unit to be used this time. The temperature set value is reset, and for example, when a is 3°C, the target heat exchanger temperature set value is set in the range of 5 to 10°C.

Next, the refrigerant temperature is determined by the temperature sensor attached to the entrance and exit of the indoor heat exchanger at a fixed timing for each indoor unit, and the refrigerant temperature is determined when the refrigerant temperature at the entrance and exit of the indoor heat exchanger becomes the same. seek.

[0025] The amount of refrigerant entering the indoor heat exchanger is constantly changing, and when the amount of refrigerant flowing into the indoor heat exchanger decreases, the indoor heat exchanger outlet temperature becomes higher than the inlet temperature. Additionally, when the amount of refrigerant flowing into the indoor heat exchanger increases, the vaporization of the refrigerant does not start from the inlet of the indoor heat exchanger 7, but starts a little further from the inlet, so the inlet temperature is higher than the outlet temperature. Become.

[0026] Here, E1' is the inlet temperature measured last time,
Let E2' be the outlet temperature measured last time, E1 be the inlet temperature measured this time, and E2 be the outlet temperature measured this time. As a result of this measurement, if E1'≧E2' and E1<E2 or E1'<E2' and E1≧E2, the target heat exchanger temperature and (E1+E2)/2 are compared and (E1+E2)
)/2 is lower, target heat exchanger temperature = (E1
+E2)/2 to change the target heat exchanger temperature. Furthermore, the temperature of the refrigerant is determined as (E1+E2)/2 for each measurement.

The control device determines the target heat exchanger temperature by repeatedly detecting the target heat exchanger temperature at a fixed timing. The control device detects such a target heat exchanger temperature for each indoor unit.

Next, the refrigerant temperature of each indoor unit determined in this way is compared with the target heat exchanger temperature for each indoor unit, and the target heat exchanger temperature and the indoor unit temperature at the current engine speed are compared. Find the difference from the minimum value of the refrigerant temperature in the heat exchanger, and find the sum.

[0029] If this value is positive, it means that the minimum value of the actual indoor heat exchanger refrigerant temperature is lower than the target heat exchanger temperature, and in this case, since the engine speed is high, It determines that a large amount of refrigerant is flowing through the engine and reduces the engine speed. Also, if this value is negative, it means that the minimum value of the actual indoor heat exchanger refrigerant temperature is higher than the target heat exchanger temperature, and in this case, the engine speed is low, so the refrigerant flow rate is It determines that the engine speed is low and increases the engine speed.

For example, now three indoor units are controlled by a remote control temperature difference a.
Cooling operation is performed with the temperature set at 3℃, and the refrigerant temperature of each indoor unit is 2.5℃ for the first unit and 7.8℃ for the second unit.
, the temperature of the third unit is 10.3°C. Here, the control device assumes that the target heat exchanger temperature, which is set in the range of 5 to 10 degrees Celsius, is 5 degrees Celsius for the first unit, 7.8 degrees Celsius for the second unit, and 10 degrees Celsius for the third unit. Compare with the refrigerant temperature of the machine.

In this case, the refrigerant temperature of the first indoor unit is below the target heat exchanger temperature, and the refrigerant temperature of the third indoor unit is above the target heat exchanger temperature. In this case, the total is (5-2.5
+10-10.3) becomes 2.2, which is a positive value, so the control device determines that the engine speed is high,
Reduce engine speed.

Here, since this refrigerant temperature changes depending on the outside air temperature, even if the remote control temperature difference is set to 3 degrees, the refrigerant temperature will be lower when the outside air temperature is low, so the target heat exchanger temperature and the refrigerant The sum of the differences from the temperature becomes a positive value, and the engine speed decreases to a speed lower than the maximum engine speed.

[0033] Furthermore, even if the remote control temperature difference is set to 0 degrees, the refrigerant temperature will be high when the outside temperature is high.
The sum of the differences between the target heat exchanger temperature and the refrigerant temperature becomes a negative value, and the engine speed increases and becomes higher than the minimum engine speed.

In this way, in order to set the engine speed based on the target heat exchanger temperature rather than the remote control temperature difference,
A preferable blowing temperature corresponding to the outside temperature can be obtained. Furthermore, even if the minimum value of the refrigerant temperature differs due to the difference in the pressure loss of each indoor unit, by making the target heat exchanger temperature vary, it is possible to prevent some indoor units from cooling too much or not cooling at all. It can be prevented.

Next, the engine rotation speed control operation during heating by the gas heat pump air conditioner will be described.

[0036] In a conventional gas heat pump air conditioner, the rotation speed of the engine changes in response to the remote control temperature difference, as in the case of cooling, but the change is within the rotation speed range depending on the total operating horsepower of the indoor unit used. It is within.

Therefore, when performing heating operation, if the remote control temperature difference is set to the maximum when the outside temperature is high, the engine will rotate at the maximum rotation speed regardless of the outside temperature, resulting in excessive heating. Furthermore, if the remote control temperature difference is set to the minimum value when the outside temperature is low, the heating effect will not increase because the engine will rotate at the minimum number of revolutions regardless of the outside temperature.

[0038] As described above, the conventional control device can cope with changes in the indoor temperature, but cannot cope with large changes in the outside temperature, so there is a problem that appropriate heating cannot be performed.

Next, another embodiment of the present invention for solving this problem will be described with reference to the drawings.

FIG. 2 is a circuit diagram of a gas heat pump air conditioner according to another embodiment of the present invention. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and 1
0 is a pressure sensor provided at the discharge part of the compressor 2. This pressure sensor 10 is for measuring the discharge pressure of the refrigerant at the discharge portion of the compressor 2, measures the discharge pressure at a fixed timing, and outputs the measurement result to the control device 9.

[0041] When performing heating operation in a gas heat pump air conditioner having such a pressure sensor 10,
First, the remote control temperature difference a is set in accordance with the desired room temperature.

Next, the control device 9 adjusts the discharge pressure of the refrigerant at the discharge section of the compressor 2 to (17
．． 5+a+b) Set based on kg/cm2. Note that b is a constant determined by the installation positions of the outdoor unit and the indoor unit. Here, for example, the remote control temperature difference a is 1.5°C, and b
If it is set to 0, the discharge pressure will be 19.0 kg/cm2.

In this case, the saturation temperature of the refrigerant having this discharge pressure in the indoor heat exchanger is approximately 50°C. Note that, if the saturation temperature of the refrigerant is as described above, the blowing temperature will be a temperature that feels neither too low nor too high.

Here, although the pressure of the refrigerant changes according to the outside temperature, the control device 9 detects the pressure sensor 1 at a certain timing.
Based on the pressure information input from 0, the engine rotation speed is controlled so that the refrigerant discharge pressure at the discharge section of the compressor 2 is always 19.0 kg/cm2.

[0045] In this way, in order to set the engine speed based on the compressor discharge pressure rather than the remote control temperature difference,
A preferable air outlet temperature corresponding to the outside temperature can be obtained, and appropriate heating can be performed.

[0046]

[Effect of the invention] As described above, according to the invention of claim 1,
A rotation speed control device can increase or decrease the rotation speed of the engine based on temperature information from a temperature sensor that measures the temperature of the refrigerant provided at the entrance and exit of the indoor heat exchanger. Thereby, appropriate cooling can be performed regardless of the outside temperature and the pressure loss of the indoor unit.

According to the second aspect of the invention, the rotational speed control device can increase or decrease the rotational speed of the engine based on pressure information from a pressure sensor that measures the discharge pressure provided at the refrigerant discharge portion of the compressor. can. Thereby, appropriate heating can be performed regardless of changes in outside temperature.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of a gas heat pump air conditioner according to the invention of claim 1.

FIG. 2 is a circuit configuration diagram of a gas heat pump air conditioner according to the invention of claim 2.

FIG. 3 is a diagram showing the relationship between the total operating horsepower of the indoor unit and the engine rotation speed.

[Explanation of symbols]

1 Engine 2 Compressor 7 Indoor heat exchanger 9 Rotation speed control device 10 Pressure sensor

Claims (2)

[Claims] 1. An engine, a heat pump circuit that sequentially connects a compressor, an outdoor heat exchanger, a pressure reducer, and an indoor heat exchanger driven by the engine, and a rotation speed control device that controls the rotation speed of the engine. In the gas heat pump air conditioner, a temperature sensor for measuring refrigerant temperature is provided at the entrance and exit of the indoor heat exchanger, and the rotation speed control device increases or decreases the rotation speed of the engine based on temperature information from the temperature sensor. A gas heat pump air conditioner characterized by comprising: 2. An engine, a heat pump circuit that sequentially connects a compressor, an outdoor heat exchanger, a pressure reducer, and an indoor heat exchanger driven by the engine, and a rotation speed control device that controls the rotation speed of the engine. In the gas heat pump air conditioner, a pressure sensor for measuring discharge pressure is provided in the refrigerant discharge part of the compressor, and the rotation speed control device increases or decreases the rotation speed of the engine based on pressure information from the pressure sensor. A gas heat pump air conditioner characterized by comprising: