JPS6121344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioner that can continuously vary the number of revolutions of a compressor for compressing refrigerant to continuously control cooling or heating capacity.

Conventionally, this type of air conditioner has always been operated with a wide variable rotation speed range of the compressor in order to maintain the room temperature as constant as possible despite changes in load. Additionally, this method generally has the advantage that the lighter the load, the higher the operating efficiency. However, as the compressor's rotational speed approaches its rated rotational speed (the highest possible rotational speed), efficiency decreases, so when load fluctuations or turbulence in the indoor air flow occur, the heating and cooling capacity is not maximized. However, if the rotation speed of the compressor is controlled at a high value, there is a problem in that it results in inefficient operation.

Therefore, in view of the above-mentioned difficulties, the present invention enables efficient heating and cooling operations with almost no loss of comfort in actual use, and allows the user to freely select the maximum value of the heating and cooling capacity depending on the situation of the room to be air-conditioned. It is an object of the present invention to provide an air conditioner as described above.

The present invention will be explained below with reference to an embodiment shown in the drawings. FIG. 1 is a block diagram of an air conditioner according to the present invention. In the figure, 1 is a compressor, and 2 is a drive motor built into the compressor 1. 3 is a heat source side heat exchanger, 4 is a blower, 5 is an expansion valve that adjusts the amount of throttling of the refrigerant passage, 6 is a user side heat exchanger that exchanges heat with the air in the air conditioning room, and 7 is a circulation fan. These constitute a refrigerant circuit, and particularly show the case where cooling operation is performed. 8 is a temperature difference output circuit that generates a temperature difference signal V _T corresponding to the difference between the room temperature of the air conditioned room and the set temperature; 9 is a temperature difference output circuit that inputs the temperature difference signal, and is suitable for controlling the rotation speed of the compressor 1 and controlling its maximum rotation speed. 10 is a compressor control device that controls the rotation speed of the compressor 1 almost in proportion to the rotation speed command signal V _N ; and a control method thereof _. The drive motor 2 is supplied with power and driven at variable speed.

FIG. 2 is a configuration diagram of the temperature difference output circuit 8 and the rotation speed command circuit 9. In the figure, 11 is a room temperature detector that detects the room temperature, 12 is a room temperature setter that sets the room temperature, and 13 is a room temperature signal from the room temperature detector 11 and a set temperature signal from the room temperature setter 12. This is a differential amplifier that outputs a temperature difference signal V _T proportional to the temperature difference ΔT. 14 is a maximum value limiting circuit, 15 and 17 are resistors, 16 is a variable resistor,
18 is an operational amplifier, 19 is a diode, and 20 is a resistor. This maximum value limiting circuit 14 functions to limit the temperature difference signal V _T to the set voltage Vd given by the sliding terminal of the variable resistor 16 to that value Vd. 21 is the minimum value limit circuit, 22, 23
is a resistor, 24 is an operational amplifier, and 25 is a diode. This minimum value limiting circuit 21 functions to limit the temperature difference signal to V _L when the temperature difference signal is smaller than the voltage V _L given by the resistors 22 and 23 . 26 is an on/off circuit, 27 is a comparator,
28, 29, 30, and 31 are resistors, 32 is a timer, and 33 is a resistor. In this on/off circuit 26, a comparator 27 and resistors 28, 29, 3
0 and 31, the temperature difference signal V _T is turned on and off with a predetermined hysteresis width in a small region, and after the comparator 32 is turned off, the timer 32 remains off for a certain period of time, for example, about 2 minutes, and the maximum value limiting circuit is activated. 14 and the lowest value limiting circuit 21 to zero, and outputs _a rotational speed command signal _VN . Note that V _CC in the figure indicates the DC power supply voltage.

In the above configuration, the temperature difference signal V _T output from the temperature difference output circuit 8 and the rotation speed command signal V _N output from the rotation speed command circuit 9 each have characteristics as shown in FIG. 3 with respect to the temperature difference ΔT. Become. In the figure, the rotational speed command signal V _N is limited to a constant value in the high range by the function of the maximum value limiting circuit 14 with respect to the temperature difference ΔT, and the limited value is the set voltage Vd. This set voltage V _d is variable using a variable resistor 16, and can be changed from the voltage V _M to V _H shown in Fig. 2. Therefore, the maximum value of the rotation speed command signal V _N can also be changed from the voltage V _M to V _H accordingly. Can be changed. Further, in the low range, the voltage is limited by the voltage V _L due to the function of the minimum value limiting circuit 21, and the on/off characteristic has a predetermined hysteresis due to the on/off circuit 26. When the rotational speed command signal V _N is given in this way, the rotational speed N of the compressor 1 is controlled almost in proportion to this value, so as shown in Figure 3, the rotational speed N is proportional to the temperature difference ΔT. The characteristics are almost the same as those of _VN .

Therefore, the rotation speed N of the compressor 1 changes between the minimum rotation speed N _L and the maximum rotation speed Nd, or becomes zero (stops). The reason for specifying the minimum rotational speed N _L here is to maintain proper oil lubrication within the compressor 1. Although it is not shown in the characteristics shown in FIG. 3, the function of the timer 32 of the on-off circuit 26 is such that when the compressor 1 is restarted after being temporarily stopped, the refrigerant gas is stabilized after the high and low pressures are balanced. A restart prohibition time is set so that the restart is activated.

Now, by inputting the rotation speed command signal V _N from the rotation speed command circuit 9, the compressor control device 10 controls the compressor 1.
By controlling the rotation speed N, the cooling capacity Q of the air conditioned room is
The characteristics are as shown in FIG. 4 with respect to the rotational speed N, and an example of the efficiency, or EER, expressed as the ratio of cooling capacity to the total electrical input in that case is as shown in the figure. In FIG. 4, as the rotational speed N increases, the cooling capacity Q also increases, but the EER decreases. Therefore, for highly efficient operation, the lower the rotational speed N, the better, and the less electrical energy consumed.

The maximum value limiting circuit 14 is provided in order to enable operation only in such a region to save energy and improve efficiency. However, if the maximum value of the rotational speed N is made too low, the cooling capacity Q will be completely insufficient, and it is natural that the engine will not be able to perform its original function. Therefore, the maximum value of the rotation speed N of the compressor 1 can be changed depending on the usage situation, and it can be set to an appropriate value based on various load conditions such as the size of the room, direction, number of people accommodated, and internally generated heat. This prevents the engine from operating at higher rotational speeds to ensure highly efficient operation at all times. Of course, on extremely hot days, when the internally generated heat is excessive, or when sufficient cooling capacity is required at the start of operation, the compressor may be
The equipment can be set so that it can be operated at the maximum rotational speed N _H that can be produced, and the maximum capacity of the equipment can be effectively utilized.

Next, the rotation speed command circuit 9, especially the maximum value limit circuit 1
Another embodiment of No. 4 is shown in FIG. In the figure, 34,
35, 36 are resistors, 37 is a heating/cooling switch, 3
8 is a capacity increase switch. Others are the same as in FIG. 2. The maximum value limiting circuit 14 in FIG.
can be used for both cooling and heating. The cooling/heating selector switch 37 changes the maximum value of the rotation speed N of the compressor 1 corresponding to cooling or heating, and the capacity increase switch 38 changes the maximum value of the rotation speed N of the compressor 1 in response to cooling or heating.
The rotation speed can be set to the maximum possible speed corresponding to each type of heating. With this configuration, the rotation speed command signal V _N has characteristics as shown in FIG. 6. In other words, the maximum value limit during heating operation can be set in the range A in the diagram, that is, from V _HH to V _MH , and during cooling operation, it can be set in the range B in the diagram, that is, the range from V _HC to V _MC . When the capacity increase switch 38 is operated, the settings are V _N =V _HH and V _N =V _HC respectively.
becomes.

In this case, the reason why V _HH >V _HC is generally set is that in a device for both heating and cooling, the required capacity during cooling may be smaller than the required capacity during heating, which is preferable in terms of efficiency.

In the case of the embodiment shown in FIG. 5, the maximum rotational speed of the compressor 1 is usually determined by the set voltage Vd given by the variable resistor 16 for cooling and heating, respectively, and the maximum rotation speed of the compressor 1 is determined by the set voltage Vd given by the variable resistor 16 for each of cooling and heating. In particular, when a large amount of cooling and heating capacity is required, the capacity increase switch 38 can be turned on as necessary.
By operating the capacity increasing switch 38 to increase the capacity and effectively utilizing the capacity of the equipment, and operating the capacity increase switch 38 again, it is possible to immediately return to the normal operating state using the variable resistor 16. The capacity amplification switch 38 can also be configured to automatically return after a certain period of time has elapsed after operation or when the temperature difference ΔT reaches a predetermined value.

Although one embodiment of the air conditioner of the present invention has been described above with reference to the drawings, the variable resistor 16 in the maximum value limiting circuit 14 may be replaced by a multi-contact changeover switch or a combination of other switches. Further, in the case of FIG. 5, the maximum setting voltage Vd provided by the variable resistor 16 may be configured to be smaller than the voltage _VH . It is also possible to digitally process signals in the rotational speed command circuit 9 including the maximum value limiting circuit 14. Further, as the compressor control device 10, a variable frequency power supply device may be used to drive a drive motor that is an induction motor at variable speed, or a drive device such as a so-called transistor motor in which the drive motor is a DC motor may be used. is possible. It is appropriate to select any of these as appropriate depending on the intended use.

As explained above, the air conditioner based on the present invention aims to improve comfort by controlling the rotation speed of the compressor steplessly to proportionally control the indoor temperature. By setting the value according to the actual usage conditions, you can always maintain high efficiency operation while maintaining comfort, and if necessary, set the maximum rotation speed to the highest value to make maximum use of the capacity of the compressor. It is expected that it will contribute to improving comfort and, in particular, to promoting energy conservation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the air conditioner of the present invention, FIG. 2 is a configuration diagram of the temperature difference output circuit and rotation speed command circuit in FIG. 1, and FIGS.
The figures are operational characteristic diagrams in FIGS. 1 and 2, respectively, and FIGS. 5 and 6 are configuration diagrams and characteristic diagrams of other embodiments of the rotation speed command circuit. 1... Compressor, 2... Drive motor, 8... Temperature difference output circuit, 9... Rotation speed command circuit, 10...
Compressor control device, 14... Maximum value limiting circuit, 16
...Variable resistor, 21...Minimum value limit circuit, 26...
...On-off circuit.

Claims (1)

[Scope of Claims] 1. A refrigerant circuit mainly including a compressor for compressing refrigerant, and a compressor that controls the rotational speed of the compressor by supplying power to a drive motor of the compressor and driving it at a continuously variable speed. a control device, a temperature difference output circuit that issues a temperature difference signal corresponding to the difference between the room temperature of the air conditioned room and a set temperature, and a rotation speed command that receives the temperature difference signal and issues a rotation speed command signal to the compressor control device. The rotation speed command circuit is manually and continuously configured to include an on/off circuit having a predetermined hysteresis characteristic that operates in response to the temperature difference signal, and a minimum value limiting circuit that limits the rotation speed command circuit to a predetermined minimum set value. Or an air conditioner configured with a maximum value limiting circuit that limits the maximum setting value that can be changed in multiple stages. 2. The air conditioner according to claim 1, wherein the means for providing the maximum setting value in the maximum value limiting circuit is constituted by a variable resistor, a switch, or a combination thereof.