JPH0526435Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a refrigeration cycle in which a compressor is driven by an inverter device.

(Prior Art) This type of refrigeration cycle has the advantage of being able to freely adjust the rotational speed of the compressor motor using an inverter device, thereby drawing out the refrigeration capacity in accordance with the thermal load. However, when the compressor motor is rotated at high speed in order to increase its refrigeration capacity, overheating of the lubricating oil causes deterioration of the oil, such as the formation of carbon sludge, and overheating of the windings causes deterioration of the insulation material. There is a possibility. If such a phenomenon occurs, the reliability of the compressor and refrigeration cycle will be significantly reduced.

In order to cope with this problem, various means have been devised to cool the compressor. The first is a configuration in which a cooling fan is provided, but while this can provide a sufficient cooling effect, it has the disadvantage of making a lot of noise during operation. The second is cooling of the compressor by a thermosiphon. but,
This is because the compressor is constantly cooled, so if the compressor is operated at a constant speed at a low room temperature, the compressor will become too cold, causing what is called a refrigerant undercharge phenomenon. Also, thirdly,
It is also conceivable to provide an injection circuit that returns part of the refrigerant into the compressor to contribute to cooling. However, when the refrigerant is returned to the compressor through this injection circuit, the refrigerant that absorbs heat and vaporizes and expands within the compressor becomes the compression load of the compressor, resulting in a phenomenon in which the load current of the compressor motor increases. However, if the compressor is driven by an inverter, if the compressor motor is switched to high-speed operation,
Immediately after this, there is a peculiar phenomenon in which the motor load current temporarily increases until the motor actually reaches high speed rotation. For this reason, in an inverter-driven refrigeration cycle, if an injection extension circuit is installed to suppress the overheating phenomenon that occurs when switching to high-speed operation, the load current increases due to the increase in high-speed rotation and the load current decreases due to the operation of the injection extraction circuit. Due to this increase, an extremely large load current flows, causing a practical problem.

(Problems to be solved by the invention) In short, in a refrigeration cycle in which the compressor is driven by an inverter device,
There was a problem in that conventional general cooling means could not be applied to cool the compressor when switching to high-speed operation.

The present invention was developed to solve the above problems, and its purpose is to cool the compressor when switching to high-speed operation without causing problems such as noise, undercharging, or overcurrent. The purpose is to provide a refrigerating cycle that can be performed reliably.

[Structure of the invention] (Means for solving the problem) The refrigeration cycle of the invention is an injection circuit that can cool a part of the refrigerant that has been compressed by a compressor and radiated heat by a condenser and returned to the compressor. In addition, a control valve that, when activated, activates the injection circuit and returns a portion of the refrigerant from the circuit to the compressor, and a control valve that, when the compressor motor is switched to high-speed operation by the inverter device, has a predetermined control valve that is delayed from the point of switching The present invention is characterized in that a delay means is provided to operate the control valve at the appropriate timing.

(Function) When the compressor is switched to high-speed operation using an inverter, the load current temporarily increases. However, the induction circuit is enabled at a predetermined time after switching to high-speed operation, so the operation of the injection The load current that increases based on this is not superimposed on the load current at the time of speed switching.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIG. 1.

Reference numeral 1 denotes a rotary type compressor, which is equipped with a well-known injection port 1a and is driven by an inverter device 2. 3 is a condenser connected to the discharge side of the compressor 1, and the refrigerant outlet side of this condenser is connected to a three-way valve 4 corresponding to a control valve. One outlet side of the three-way valve 4 is connected to a cooler 6 via a capillary tube 5, and the refrigerant outlet side of the cooler 6 is connected to a suction pipe 7.
It is connected to the suction side of the compressor 1 via. On the other hand, the other outflow side of the three-way valve 4 is connected to the injection exit port 1a of the compressor 1 via an injection exit capillary tube 8. The compressor 1 is connected from the three-way valve 4 through the injection exit capillary tube 8.
The conduit leading to the refrigerant is compressed by the compressor 1 and radiated heat by the condenser 3.
An injection extraction circuit 9 is constructed which can return the air to the inside and cool it. Then, the inverter device 2
For example, when receiving a quick cooling operation command for the refrigerator,
For example, the output frequency is increased from 60Hz to 90Hz to rotate the compressor motor of compressor 1 at high speed. Further, the three-way valve 4 is
Normally, only the flow path to the cooler 6 side is open, and when the compressor 1 is switched to high-speed operation as described above, the refrigerant is turned on after a predetermined time delay from the switching point using a timer device as a delay means. Not only the cooler 6 side but also the injection circuit 9
It operates so that the refrigerant can also flow to the side, and operates again at the end of high-speed operation to flow the refrigerant only to the cooler 6.

Next, the operation of the above configuration will be explained. During normal cooling operation, the compressor 1 is driven by the inverter device 2 at an output frequency of, for example, 60 Hz. Here, when a rapid operation command is given, the inverter device 2 increases the output frequency to, for example, 90 Hz, thereby causing the compressor motor to rotate at a high speed. At the beginning of such a switch to high-speed operation, the compressor motor is rotating at a speed equivalent to 60 Hz, so a large load current flows through the compressor motor. However, after a certain amount of time has passed and the compressor motor begins to rotate steadily at a speed equivalent to 90Hz, its load current decreases. Furthermore, as the compressor motor begins to rotate at high speed, the temperatures of the lubricating oil and the windings gradually begin to rise. However, when the timer device that performs the timing operation after switching to high-speed operation of the compressor 1 counts a predetermined time, the three-way valve 4 is activated and the injection extraction circuit 9 is enabled, so that the injection exit port 1a of the compressor 1 is Some of the refrigerant is returned. As a result, the refrigerant returned to the injection port 1a is vaporized and
Since the inside of the compressor 1 is cooled by the expansion, a rise in temperature of the compressor 1 can be suppressed.
In addition, since the refrigerant is returned to the compressor 1 by activating the injection circuit 9, the compression load of the compressor 1 increases, and therefore the load current of the compressor motor increases. However, at this point, the compressor motor has already reached a steady state and the load current has settled to a relatively small value. The load current of the motor will not become excessive.

As described above, in this embodiment, when the compressor motor is operated at high speed by the inverter device 2, the injection execution circuit 9 can be enabled to cool the compressor 1. Abnormal temperature increases in the windings can be prevented, and the reliability of the compressor 1 and the refrigeration cycle can be improved. Moreover, unlike the cooling fan, it does not generate noise, and unlike the thermosiphon, it cools the compressor 1 only during high-speed operation, so there is no possibility that the compressor 1 will become overcooled. There is no possibility that the refrigerant undercharge phenomenon will occur. Furthermore, even if there is a situation where the load current of the compressor motor increases due to the activation of the induction circuit 9, the activation circuit 9 is activated with a delay from the time when the compressor 1 is switched to high-speed operation. The increase in load current caused by switching to high-speed operation and the increase in load current caused by activation of the injection circuit 9 do not overlap, thereby reliably preventing the generation of excessive load current.

Next, a description will be given with reference to FIG. 2 showing a second embodiment of the present invention. The same parts as those in the first embodiment are given the same reference numerals, explanations thereof are omitted, and differences will be described. 10 is a gas-liquid separator, the inlet side of which is connected to the condenser 3 via a first capillary tube 11, and the liquid phase outlet side connected to the cooler 6 side via a second capillary tube 12. has been done. On the other hand, the injection circuit 13 has the following configuration.

That is, one end side of the injection pipes 14 and 15 are connected to the gas phase outflow part and the liquid phase outflow part of the gas-liquid separator 10, respectively, and the other end side of each pipe 14 and 15 is commonly connected to separate the gas and liquid. The gas refrigerant and liquid refrigerant from the separator 10 are made to join together, and this common connection is connected to the control valve 17 via the injection exit capillary tube 16, and further connected to the control valve 17.
The outflow side of the compressor 7 is connected to the injection port 1a of the compressor 1. Here, the control valve 17 is closed during normal operation, and when the inverter device 2 is switched to rotate the compressor motor at high speed based on, for example, a rapid operation command, a timer device causes a predetermined rotation speed from the time of switching. The system opens after a time delay and closes again when high-speed operation ends.

Also in the above configuration, since the compressor 1 is cooled by the injection circuit 13, cooling can be reliably performed during high-speed operation without causing noise or undercharge phenomena. In addition, since the injection extension circuit 13 operates with a delay from the time when the compressor motor is switched to high-speed operation, the load current increases due to the switch to high-speed operation and the load current increases due to the operation of the injection extension circuit 13. It is possible to reliably prevent the load current of the compressor motor from becoming excessive without overlapping.

In each of the embodiments described above, the injection circuits 9 and 13 are operated after a predetermined period of time measured by a timer device from the time of switching to high-speed operation, but the present invention is not limited to this, and for example, A temperature sensor may be provided as a delay means for detecting this, and the injection circuit may be activated after the compressor temperature rises to a set temperature (for example, 120° C.) after the compressor is switched to high-speed operation. Even in this case, by selecting the set temperature value appropriately, it is possible to activate the injection circuit after the compressor motor has settled into a steady state of high-speed rotation, so the desired purpose can be fully achieved. can do.

[Effects of the invention] As stated above, the refrigeration cycle of the invention has the following effects:
Since the compressor during high-speed operation is cooled by an injection circuit that operates with a delay from the time of switching to high-speed operation, problems such as noise and undercharge are not caused, and the load current of the compressor motor is reduced. This has the effect that the compressor can be cooled without increasing the temperature excessively.

[Brief explanation of drawings]

FIGS. 1 and 2 are refrigeration cycle configuration diagrams showing the first and second embodiments of the present invention, respectively. In the figure, 1 is a compressor, 2 is an inverter device, 3 is a capacitor, 4 is a three-way valve (control valve), 6
is a cooler, 9, 13 is an injection circuit, 1
7 is a control valve.

Claims (1)

[Scope of utility model registration request] In a compressor that is driven by an inverter device, the refrigerant is compressed by the compressor and radiated by a condenser, and a part of the refrigerant is returned to the compressor to cool the compressor. a control valve that enables a part of the refrigerant from the circuit to return to the compressor; and a control valve that activates the control valve at a predetermined time delayed from the time of switching when the compressor motor is switched to high-speed operation by the inverter device. A refrigeration cycle characterized by being provided with activation delay means.