JP2878727B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an air conditioner provided with a refrigerant heater.

(Prior Art) In an air conditioner, a heat pump refrigeration cycle having a variable capacity compressor and a refrigerant heater are provided, and the refrigerant heating operation of the refrigerant heater and the heat pumping operation of the heat pump refrigeration cycle are combined. Some perform heating operation. An example is shown in FIG.

Reference numeral 1 denotes a variable capacity compressor. The compressor 1 has a four-way valve 2, an outdoor heat exchanger 3, a check valve 4, an expansion valve 5, an indoor heat exchanger 6,
And the check valve 7 are sequentially communicated to constitute a heat pump refrigeration cycle.

The communication between the check valve 4 and the expansion valve 5 causes the compressor 1
The solenoid on-off valve 8 and the refrigerant heater 9 are sequentially communicated to the refrigerant suction side pipe.

The refrigerant heater 9 is provided with a gas burner 10 attached thereto, and the gas burner 10 is connected to a fuel supply source (not shown) via a proportional valve 11.

That is, during the cooling operation, the compressor 1 is started with the electromagnetic on-off valve 8 closed, the refrigerant flows in the direction of the solid line arrow in the drawing to make the outdoor heat exchanger 3 a condenser and the indoor heat exchanger 6 to evaporate. I try to work as a container.

During the heating operation, the compressor 1 is started with the electromagnetic on-off valve 8 opened, the four-way valve 2 is switched, the refrigerant heater 9 is operated (the gas burner 10 is burned), and the direction indicated by the dashed arrow is shown. The indoor heat exchanger 6 by flowing a refrigerant through the condenser,
The refrigerant heater 9 functions as an evaporator.

At the start of the heating operation, the operating frequency of the compressor 1 is set to a value higher than usual, and the refrigerant circulation amount is increased to speed up the rise of the heating capacity.

(Problems to be Solved by the Invention) However, in order to secure the reliability of the compressor 1 and in particular to suppress the oil discharge amount of the compressor 1, there is a limit in increasing the operating frequency of the compressor 1, The limit was about 1.5 times the normal value.

On the other hand, if the outside air temperature is extremely low (−10 ° C. to −20
° C), the effect of increasing the operating frequency was small, and it was difficult to obtain a good rise in the heating capacity.
For example, when the outside air temperature is −15 ° C., even if the operating frequency is increased, the amount of the circulated refrigerant does not become about half of that when the outside air temperature is 0 ° C.

The present invention has been made in view of the above-described circumstances, and an object thereof is to maximize the refrigerant circulation amount while securing the reliability of the compressor at the start of the heating operation, It is an object of the present invention to provide an air conditioner capable of accelerating the rise of the heating capacity even when the outside air temperature is extremely low.

[Means for Solving the Problems] The present invention relates to a heat pump refrigeration cycle in which a variable capacity compressor, a four-way valve, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger are sequentially communicated. A refrigerant heater provided in the refrigeration cycle, a refrigerant temperature sensor for detecting a refrigerant refrigerant temperature discharged from the compressor, a current sensor for detecting an input current to the compressor, operation of the compressor, switching of a four-way valve Means for performing a heating operation by operating the refrigerant heater, and at the start of the heating operation, during a period until the detection temperature of the refrigerant temperature sensor reaches a set value, the detection current of the current sensor exceeds a predetermined value. Increase the operating frequency of the compressor within a range not
Means for controlling the operating frequency of the compressor so as to keep the detected current at a predetermined value when the detected current of the current sensor is going to exceed a predetermined value.

(Operation) At the start of the heating operation, the operating frequency of the compressor is increased until the temperature of the refrigerant discharged from the compressor reaches a set value and the input current to the compressor does not exceed a predetermined value.

(Example) Hereinafter, a first example of the present invention will be described with reference to the drawings. In the drawings, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, a refrigerant temperature sensor 12 is attached to a refrigerant discharge side pipe of the compressor 1.

20 is a control unit that performs control over the entire air conditioner,
It consists of a microcomputer and its peripheral circuits.

The control unit 20 includes a four-way valve 2, an electromagnetic on-off valve 8, a proportional valve 1
1, refrigerant temperature sensor 12, operation unit 21, indoor temperature sensor 22,
And the inverter circuit 23.

The inverter circuit 23 rectifies the voltage of the commercial AC power supply 24, converts the rectified voltage into AC having a predetermined frequency and voltage by switching according to a command from the control unit 20, and supplies the AC to the compressor 1 as drive power.

A current sensor 25 is provided on a power supply line from the power supply 24 to the inverter circuit 23, and the current sensor 25 detects an input current to the compressor 1.

The control unit 20 performs the heating operation by operating the compressor 1, switching the four-way valve 2, opening the electromagnetic on-off valve 8, and operating the refrigerant heater 9 (combustion of the gas burner 10) in addition to the normal cooling operation control. Functional means to be executed, and at the start of the heating operation, the compressor 1 is controlled so that the detected temperature of the refrigerant temperature sensor 12 reaches a set value and the detected current of the current sensor 25 does not exceed a predetermined value.
Function means for increasing the operating frequency F of the vehicle.

Next, the operation of the above configuration will be described with reference to FIG.

When a cooling operation start operation is performed by the operation unit 21, the control unit 20
Starts the compressor 1 with the electromagnetic on-off valve 8 closed, and forms a cooling cycle by flowing the refrigerant in the direction of the solid arrow in FIG. That is, the outdoor heat exchanger 3 functions as a condenser, and the indoor heat exchanger 6 functions as an evaporator, and cool air is blown into the room.

When the start operation of the heating operation is performed by the operation unit 21, the control unit 20
Starts the compressor 1 with the electromagnetic on-off valve 8 released, switches the four-way valve 2, further operates the refrigerant heater 9 (burns the gas burner 10), and moves in the direction of the dashed arrow in FIG. The refrigerant flows to form a heating cycle. That is, the indoor heat exchanger 6 functions as a condenser, and the refrigerant heater 9 functions as an evaporator, so that warm air is blown into the room.

At the start of this heating operation, the control unit 20
Until the detected temperature of 12, that is, the refrigerant temperature discharged from the compressor 1 reaches a set value, for example, 45 ° C., and the detected current of the current sensor 25, that is, the input current to the compressor 1, does not exceed a predetermined value. Increase the operating frequency F.

Thus, by raising the operating frequency F of the compressor 1, the refrigerant circulation amount G of the refrigeration cycle increases, and the rise of the heating capacity becomes faster.

By the way, the refrigerant circulation amount G is equal to the operating frequency F of the compressor 1.
And the specific volume v of the suction gas of the compressor 1 and is expressed by the following equation.

G = k · F · 1 / v ≒ α · I where k and α are constants, and I is the compressor 1 (inverter circuit 2
4) Input current to.

That is, by keeping the input current I constant, when the specific volume v of the suction refrigerant gas is large (low outside air temperature), the operating frequency F can be increased, and the specific volume v of the suction refrigerant gas has decreased. At this time (when the temperature of the refrigeration cycle has risen), the operating frequency F is automatically lowered, and the refrigerant circulation amount G is kept substantially constant.

Therefore, an appropriate predetermined value is set as a limit value for the input current I, and the operating frequency F of the compressor 1 is increased within a range where the input current I does not exceed the predetermined value, thereby ensuring the reliability of the compressor 1. However, it is possible to increase the refrigerant circulation amount G to the maximum while suppressing the oil discharge amount of the compressor 1 in particular. Even if the outside air temperature is extremely low, the rise of the heating capacity can be accelerated.

In addition, in a situation where the input current I tends to exceed the predetermined value, the operating frequency F of the compressor 1 is controlled (decreased) so as to keep the input current I at the predetermined value, so that the refrigerant circulation amount G increases too rapidly. A situation can be prevented beforehand, and a problem that the amount of oil discharged from the compressor 1 increases can be surely prevented, and efficient startup of the heating operation is possible.

Where the temperature detected by the refrigerant temperature sensor 12 is a set value.
When the temperature reaches 45 ° C., the control unit 20 sets the operation frequency F to a normal value, and enters a steady operation.

The present invention is not limited to the above embodiment, and various modifications can be made without changing the gist.

[Effects of the Invention] As described above, according to the present invention, a heat pump refrigeration cycle in which a variable capacity compressor, a four-way valve, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger are sequentially communicated, A refrigerant heater provided in a cycle, a refrigerant temperature sensor for detecting a refrigerant refrigerant temperature discharged from the compressor, a current sensor for detecting an input current to the compressor, operation of the compressor, switching of a four-way valve, and Means for performing a heating operation by operating the refrigerant heater, and a range in which the detection current of the current sensor does not exceed a predetermined value during a period until the detection temperature of the refrigerant temperature sensor reaches a set value at the start of the heating operation. Means for increasing the operating frequency of the compressor and controlling the operating frequency of the compressor to maintain the detected current at a predetermined value in a situation where the current detected by the current sensor is going to exceed a predetermined value. At the start of operation, the refrigerant circulation amount can be increased to the maximum while ensuring the reliability of the compressor, and even when the outside air temperature is extremely low, the heating capacity can be quickly started, and the refrigerant circulation amount can be increased. It is possible to reliably prevent a problem that the amount of oil discharged from the compressor is increased by preventing a situation in which the amount of oil suddenly increases is increased, thereby providing an air conditioner capable of efficiently starting the heating operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a refrigeration cycle and a control circuit in one embodiment of the present invention, FIG. 2 is a diagram showing a change in an operating frequency F in the embodiment, and FIG. FIG. 3 is a diagram showing a cycle configuration. 1 ... variable capacity compressor, 2 ... 4-way valve, 3 ... outdoor heat exchanger, 5 ... expansion valve (decompressor), 6 ... indoor heat exchanger,
8 ... electromagnetic on-off valve, 9 ... refrigerant heater, 10 ... gas burner, 12 ... refrigerant temperature sensor, 20 ... control unit, 23 ... inverter circuit, 25 ... current sensor.

Claims (1)

(57) [Claims] 1. A variable capacity compressor, a four-way valve, an outdoor heat exchanger,
A heat pump refrigeration cycle in which a decompressor and an indoor heat exchanger are sequentially communicated; a refrigerant heater provided in the refrigeration cycle; a refrigerant temperature sensor for detecting a refrigerant discharge temperature of the compressor; A current sensor for detecting an input current; a means for performing a heating operation by operating the compressor, switching a four-way valve, and operating a refrigerant heater; and at the start of the heating operation, the detected temperature of the refrigerant temperature sensor is During the period until the set value is reached, the operating frequency of the compressor is increased within a range where the detected current of the current sensor does not exceed a predetermined value, and in a situation where the detected current of the current sensor is going to exceed the predetermined value, the detected current is increased. Means for controlling the operating frequency of the compressor so as to maintain the operating frequency at a predetermined value.