JP3524997B2 - Air conditioner - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air conditioner suitable for a chlorine-free refrigerant.

[0002]

2. Description of the Related Art HCFC type refrigerant R22 is widely used as a refrigerant generally used in air conditioners, refrigerators and the like. R22 is said to destroy the ozone layer because it contains chlorine in the molecule, and since it adversely affects the global environment, the use of refrigerants such as R22 is in the direction of worldwide reduction, and in the future it will be fully used. It is prohibited. For this reason, R
There is an urgent need to develop alternative refrigerants that can replace No. 22 and devices that support these alternative refrigerants.

HFC containing no chlorine as an alternative refrigerant
A single or a mixture of a plurality of substances is currently a promising candidate, and examples thereof include a R32 / 125 two-type mixed refrigerant and an R32 / 125 / 134a three-type mixed refrigerant.

[0004]

By the way, since R22, an HCFC-based refrigerant currently used, has chlorine in its molecule, chlorine in the refrigerant reacts with the sliding member of the compressor,
It was acting as an extreme pressure additive. For this,
Even when the lubrication was incomplete such as the oil film running out during the operation of the compressor and the sliding member was in direct contact, the progress of wear in the sliding part was relatively gradual.

However, since the HFC type refrigerant does not contain chlorine in its molecule, it cannot be expected to act as an extreme pressure additive for the refrigerant. Therefore, if lubrication is incomplete and the oil film runs out and the sliding members come into direct contact, severe wear will occur, and it is essential to take measures to prevent direct contact of the sliding members in order to improve reliability. Become.

In particular, the oil film forming property of the sliding member is better as the oil film is better formed at a high operating frequency, and the discharge pressure is lower and the load is smaller. On the other hand, however, the oil film runs out when the operating frequency is lowered. It is known that the amount of contact of the sliding member increases after waking up. This is due to the fact that the oil film does not easily form a low operating frequency, and when the operating frequency falls, the drop in discharge pressure lags behind the decrease in operating frequency, causing a temporary heavy load condition. It is considered that the formability deteriorates and causes contact.

Therefore, the present invention provides an air conditioner that ensures stable lubrication and improves reliability by controlling the operation so that the oil film is unlikely to be destroyed when the operating frequency decreases. It is an object.

[0008]

To achieve the above object, the present invention provides a compressor, an indoor heat exchanger, and an outdoor heat exchange.
Refrigerant does not contain chlorine as it is equipped with a vessel, throttle mechanism and four-way valve
Change the output frequency with the refrigerant circuit that uses HFC refrigerant
Variable control of the compressor from low speed rotation to high speed rotation
Room temperature and temperature setter detected by frequency converter and sensor
Depending on the difference between the temperature setting values of the
And a converter control device for providing the frequency converter.
When the operating frequency is changed to a low operating frequency, the descending speed of the operating frequency is controlled at 1/9 Hz / sec or less.

Alternatively, the converter controller is configured to
Change the wave number converter from high operating frequency to low operating frequency
At this time, when the lowering speed of the operating frequency falls within the range of 55% or less of the rated operating frequency of the compressor, the lowering speed is controlled to be slower than the lowering speed up to 55% of the rated operating frequency.

Alternatively, the operating frequency of the refrigerant circuit is
A control circuit for lowering the discharge pressure of the compressor is provided at the stage before the descent .

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

According to such an air conditioner, the compressor is controlled from low speed rotation to high speed rotation in accordance with the operating frequency due to the air conditioning load.

During this operation, when the operating frequency drops, the discharge pressure drops as the compressor and the operating frequency drop speed drop, and as a result, an oil film is hard to form but a heavy load does not occur. The severe lubrication condition of oil film destruction is avoided. For this reason, a stable lubrication state is ensured.

[0020]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings of FIGS.

In FIG. 1, reference numeral 1 denotes a compressor provided in the refrigerant circuit 3. Inside the refrigerant circuit 3 outside the compressor 1, indoor heat is used as an evaporator during cooling and a condenser during heating. An exchanger 5, an outdoor heat exchanger 7 that serves as a condenser during cooling and an evaporator during heating, an expansion valve 9 as a throttle mechanism, and a four-way valve 1.
1 are provided respectively. The four-way valve 11, the outdoor heat exchanger 7, the frequency converter 13, the outdoor fan 15, and the converter control device 17 are arranged in an outdoor unit (not shown). On the other hand, the display operation unit 19, the indoor fan 21, and the indoor heat exchanger 5 are arranged in an indoor unit (not shown), and by switching the four-way valve 11, the compressor 1 discharges during the heating operation mode. The generated refrigerant passes through the indoor heat exchanger 5 → the expansion valve 9 → the outdoor heat exchanger 7 as shown by the solid arrow,
The circulation cycle of returning to the compressor 1 again via the four-way valve 11 is repeated.

Further, in the cooling operation mode, by switching the four-way valve 11, the refrigerant discharged from the compressor 1 passes through the outdoor heat exchanger 7 → the expansion valve 9 → the indoor heat exchanger 5 and flows in the four-way direction. The circulation cycle of returning to the compressor 1 again via the valve 11 is repeated.

As the refrigerant, an HFC refrigerant containing no chlorine, that is, a mixed refrigerant of R32 / R125 is used. In this case, the refrigerant is not limited to the above mixed refrigerant and other HFC refrigerant may be used. Other HFC refrigerants include difluoromethane (R32), pentafluoroethane (R125), and 1, which have a higher discharge pressure than the R22 refrigerant as a single refrigerant.
1,2,2-tetrafluoroethane (R134), 1,
1,2-trifluoroethane (R143), 1,1,1
-Trifluoroethane (R143a) 1,1-difluoroethane (R152a) and the like.

The HFC refrigerant is not only used as a single refrigerant, but may be a mixture of two or more HFC refrigerants. As an HFC mixed refrigerant, R125 /
R143a / R134a mixed refrigerant, R32 / R134
a mixed refrigerant, R32 / R125 mixed refrigerant, R32 /
R125 / R134a mixed refrigerant, further R125 /
A mixed refrigerant of R143a is considered.

When a non-azeotropic mixed refrigerant such as R32, R125, R134a is used, a temperature gradient occurs in the condensation temperature, but the temperature should be detected in the middle of the condenser (outdoor heat exchanger 7). Thereby, the relative error between temperature and pressure can be suppressed as much as possible.

Further, since the non-azeotropic mixed refrigerant is used as the HFC refrigerant, the condensing temperature does not correspond to the condensing pressure on a one-to-one basis, and the temperature changes at the inlet and outlet of the condenser (outdoor heat exchanger 7). The range of erroneous detection may increase depending on the condensing temperature detection position.However, the erroneous detection range can be reduced by detecting the condensing pressure based on the temperature of the middle part of the condenser even for such a problem. Therefore, the stable condensation temperature can be detected.

On the other hand, in the frequency converter 13, the AC voltage of the power supply 14 is supplied with the DC voltage by the rectifier circuit 18, and the output frequency is about 27-by the digital control signal.
It can be continuously changed in the range of 83 Hz, whereby the compressor 1 is variably controlled from low speed rotation to high speed rotation.

The digital control signal applied to the frequency converter 13, that is, the frequency setting signal, is transferred to the converter control device 1.
7 is the output. The converter control device 17 includes the display operation unit 1
The operation signal of 9 and the temperature data of the temperature sensors 22 and 23 are input as inputs to the microprocessor, and the four-way valve 1 is subjected to logical operation processing according to a preset program.
1. A load such as a fan motor is operated and a frequency setting signal is given to the frequency converter 13, and at the same time, the operating state of the compressor 1 is displayed on the display section (LED) of the display operation section 19.

FIG. 2 is a front view of the panel of the display / operation unit 19, 25 is a body spray (LED) for displaying the number of revolutions of the compressor 1 as a performance level, 27 is a temperature setting device for setting room temperature, and 29 is indoors. Changeover switches for changing the strength of the fan 21, reference numerals 31, 32, 33 select an air conditioner for either cooling or heating, or an operation stop switch for stopping the air conditioner, and 35, 37 display for displaying the operating state. The respective devices (LEDs) are shown. Then, the temperature setting signal of the temperature setting device 27, the fan strength designating signal of the changeover switch 29, and the operation command signals of the operation stop switches 31, 32, 33 are output from the display operation unit 19, and all these signals are converted. It is added to the controller 17. at the same time,
The converter control device 17 gives a signal to turn on the display 25 and the indicators 35 and 37 to the display operation unit 19.

Next, the temperature sensor 23 detects the room temperature, the temperature sensor 22 detects the condensing temperature of the refrigerant, and the converter controller 17 determines the allowable value of the pressure of the refrigeration cycle based on the detected temperature information. This is to limit the maximum frequency so that it will not be exceeded.

Here, the converter control device 17 is mainly composed of a microcomputer (hereinafter referred to as a microcomputer), and its control specification is made to correspond to the microcomputer program.
Complex control is possible. Therefore, it is possible to easily output the frequency setting signal corresponding to the difference between the room temperature detected by the sensor 23 and the temperature setting value of the temperature setting device 27, which allows the air conditioning load (air conditioning load) to be met. The rotation speed of the compressor 1 can be controlled.

FIG. 3 shows the difference between room temperature and temperature set value (Ts).
An example of the operating frequency (Hz) of the compressor 1 corresponding to each zone is shown by dividing the zone into a plurality of zones (A to I) at certain temperature intervals, for example, at intervals of 0.5 ° C. In this figure, when the temperature difference is large, the high operating frequency Hz
Therefore, it means the operation control for rotating the compressor 1 at a high speed. Further, as the temperature difference becomes smaller, the operating frequency becomes lower, which means operating control in which the compressor 1 is rotated at a low speed.

Further, the converter control device 17 determines a zone having a difference between the room temperature and the set value when the operating time in the same zone exceeds a predetermined value, and the zone is assigned to the zone. With the operation control at the operating frequency Hz,
Especially, the descending speed when the operating frequency falls is 1/9 Hz / s
It has a control function of controlling below ec.

When the operating frequency falls to 55% or less of the rated operating frequency, the operating frequency drops to 55% of the rated operating frequency.
It has a control function to control the descending speed slower than the descending speed up to%.

As shown in FIG. 4, when the vertical axis represents the operating frequency Hz and the horizontal axis represents the time t, the descending speed is ΔH when the operating frequency in the descending region is ΔHz and the time at that time is Δt.
It is set by the formula of z / Δt [Hz / sec].

An example of changes in the room temperature and the rotation speed of the compressor 1 when the air conditioner having such control specifications is operated will be described with reference to FIG. The drawing shows the one in the heating operation mode. At the beginning, since the room temperature becomes as large as the temperature set value Ts, the compressor 1 is operated at the highest operation frequency. Eventually, the room temperature rises, the difference from the temperature set value Ts is managed by the converter control device 17 via the sensors 22 and 23, and when the difference becomes small, the zone where the engine should be operated at a lower rotation speed is entered. At time T1, the rotation speed of the compressor 1 decreases. Thereafter, when the room temperature further rises and the difference from the temperature set value Ts becomes smaller, the zone to be operated at the lower rotation speed is entered, and at this time T2, the rotation speed of the compressor 1 is reduced, When the room temperature reaches the temperature set value Ts and the difference becomes zero, the compressor 1 is stopped by repeating the stepwise down. When the operating frequency was lowered, electrodes were embedded in the bearing of the compressor 1 and the amount of direct contact of the sliding member due to the oil film breakage of the bearing was measured, and the following results were obtained.

That is, in FIGS. 6 and 7, the descending speed of the area a is 1 /
3 Hz / sec, and FIG. 8 shows measurement results performed at 1/6 Hz / sec. Looking at this measurement result, in particular,
As shown in FIG. 8, it can be seen that the contact amount is large under the condition that at least a part of the range is 55% or less of the rated operating frequency Hz.

At the same time, a delay is recognized until the discharge pressure Pd drops. Due to this delay, it is difficult to form an oil film, and a state where the load remains large temporarily occurs and the oil film runs out, resulting in a large amount of contact. It is considered to be a thing.

On the other hand, as shown in FIG. 9, the decrease of the discharge pressure Pd follows the decrease of the operating frequency by making the decrease rate of the operating frequency in the region a slower to 1/9 Hz / sec or less. The severe condition of running out of oil film was avoided, and the amount of contact was kept small.

10 and 11 show the rated operating frequency of 55.
FIG. 6 shows the measurement results when the descending speed is slower than the descending speed up to 55% when a part of the descending is applied to the range of less than or equal to%, and when entering.

According to this measurement result, the drop in the discharge pressure Pd almost follows the drop in the operating frequency, the severe condition of oil film breakage was avoided, and the contact amount was suppressed to a small level.

FIG. 12 shows another embodiment.
When the operating frequency is lowered, the control circuit 39 is provided to increase the air volume of the outdoor fan 15 of the outdoor heat exchanger 7 serving as the condenser for a certain period of time before shifting to the lowering.

An air volume up signal is sent to the control circuit 39 from the converter control device 17 with a time lag before the down signal is sent to the frequency converter 13.

Since the other constituent elements are the same as those in the above-mentioned embodiment, the same reference numerals are given and detailed description thereof will be omitted.

Therefore, according to this embodiment, before the operating frequency is lowered, the indoor fan 15 is raised and the heat exchange rate is increased → the condensation temperature Te decreases → the discharge pressure Pd decreases,
It is possible to avoid the occurrence of a large load when the operating frequency is lowered, which deteriorates the oil film forming property, and as shown in the measurement result of FIG. 13, the contact amount of the sliding member can be suppressed to be small.

FIG. 14 shows another embodiment.
When the operating frequency is decreased, the control circuit 43 for restricting the expansion valve 9 for a certain period of time is provided before the operation is started.

To the control circuit 43, before sending the down signal from the converter control device 17 to the frequency converter 13,
A signal for squeezing the expansion valve 9 is sent with a time lag.

Since the other constituents are the same as those in the above-mentioned embodiment, the same reference numerals are given and detailed description thereof will be omitted.

Therefore, according to this embodiment, when the expansion valve 9 is throttled for a certain period of time before the operating frequency is lowered, the discharge pressure Pd is temporarily increased, but the refrigerant flow rate decreases → the suction pressure decreases → the discharge pressure. It is possible to avoid the occurrence of a heavy load when the operating frequency is lowered such that Pd decreases and the oil film forming property deteriorates, and the contact amount of the sliding member can be suppressed to be small as shown in the measurement result of FIG. Become.

In this case, it is also possible to open the expansion valve 9 and then carry out operation control in which the operation frequency is lowered.

In the case of this embodiment, when the expansion valve 9 is opened, the discharge pressure Pd temporarily drops. As a result, it is possible to avoid the occurrence of a heavy load when the operating frequency is lowered, which deteriorates the oil film forming property, and the contact amount of the sliding member can be suppressed to be small as shown in the measurement result of FIG.

In particular, in the case of this embodiment, the liquid refrigerant easily returns to the compressor 1, but it can be dealt with by mounting the accumulator in front of the compressor 1.

FIG. 17 shows another embodiment.
In the heating operation mode, the refrigerant circuit 3 is provided with a control circuit 45 that switches to the defrosting operation mode for a certain period of time before the operation frequency is lowered.

The control circuit 45 is a hot gas bypass circuit. One end of the control circuit 45 is connected to the discharge side of the compressor 1 and the other end is connected to the inlet side of the outdoor heat exchanger 7, and has an opening / closing valve 47. To the on-off valve 47, a signal for opening for a certain time is sent with a time lag before the down signal is sent from the converter control device 17 to the frequency converter 13.

Since the other constituents are the same as those in the above-described embodiment, the same reference numerals are given and detailed description thereof will be omitted.

Therefore, according to this embodiment, since the on-off valve 47 is opened in the heating operation mode,
The hot gas is sent to the inlet side of the outdoor heat exchanger 7 functioning as an evaporator for defrosting.
The discharge pressure Pd decreases when the valve is opened, and then the operating frequency decreases, which deteriorates the oil film forming property. As a result, it is possible to avoid the occurrence of a heavy load during the decrease, and as shown in the measurement results of FIG. The contact amount of the sliding member can be kept small.

In this case, by switching the four-way valve 11 by the signal 49 from the converter control device 17 as shown in FIG. 19, in the heating operation mode, high temperature gas is directed to the inlet side of the heat exchanger 5 which is the indoor side. Even when the reverse defrosting is performed, the contact amount of the sliding member can be suppressed to be small as shown in the measurement result of FIG.

FIG. 21 shows another embodiment.
The refrigerant circuit 3 is provided with a release circuit 51 that releases the discharge pressure of the compressor 1 when the operating frequency decreases.

One end of the release circuit 51 is connected to the discharge side of the compressor 1, and the other end is connected to the intake side of the compressor 1. The release circuit 51 is provided with a release valve 53.

The release valve 53 includes a converter control device 17
Before sending the down signal from the frequency converter 13 to the frequency converter 13, the signal to be opened is sent with a time lag for a certain period of time.

Since the other constituents are the same as those in the above-described embodiment, the same reference numerals are given and detailed description thereof will be omitted.

Therefore, according to this embodiment, since the release valve 53 is opened when the operating frequency is lowered, it is possible to prevent the discharge pressure Pd from being lowered and to cause a heavy load when the operating frequency is lowered. As shown in the measurement results of FIG. 22, the contact amount of the sliding member can be suppressed to be small.

FIG. 23 shows another embodiment, in which the refrigerant circuit 3 is provided with a refrigerant tank 65 in parallel with the expansion valve 9.

The first opening / closing valve 5 is provided before and after the refrigerant tank 55.
7 and a second on-off valve 59 are provided respectively. First,
The opening / closing timing of the second opening / closing valves 57 and 59 is normally in the closed state, and the converter control device 17 causes the frequency converter 13 to open.
A signal for opening the first opening / closing valve 57 is sent before the drop signal is sent to, and the liquid refrigerant is temporarily stored in the refrigerant tank 55 and the discharge pressure Pd drops. Valve 5
A signal that the second opening / closing valve 59 is opened is sent at the same time as 7 is closed, and after the liquid refrigerant is discharged, a signal that the second opening / closing valve 59 is closed is subsequently sent.

Since the other constituents are the same as those of the above-mentioned embodiment, the same reference numerals are given and detailed description thereof will be omitted.

Therefore, according to this embodiment, it is possible to prevent the discharge pressure Pd from decreasing when the operating frequency decreases, and to cause a large load when the operating frequency decreases, as shown in the measurement results of FIG. The contact amount of the sliding member can be kept small.

[0067]

As described above, according to the present invention, it is possible to perform operation control in which the oil film is unlikely to run out when the operating frequency is lowered, so that a stable lubrication state is secured and reliability is improved. Can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an air conditioner according to the present invention.

FIG. 2 is an explanatory diagram of a display operation unit.

FIG. 3 is an explanatory diagram showing an example of a relationship between a temperature difference between a temperature setting value and room temperature and a compressor operating frequency.

FIG. 4 is an explanatory diagram of a descending speed of an operating frequency.

FIG. 5 is an explanatory diagram showing a relationship between a compressor rotation speed, a discharge pressure, and a suction pressure with respect to a temperature difference between a temperature set value and room temperature.

FIG. 6 is an explanatory diagram of a conventional example showing the measurement result of the contact amount when the decreasing rate of the operating frequency is 1/3 Hz / sec.

FIG. 7: The descending speed of the operating frequency is 55 of the rated operating frequency.
When falling in the range of% or less, the descending speed is 1 /
Explanatory drawing of the prior art example which showed the measurement result of the amount of contact when it was 3 Hz / sec.

FIG. 8: The descending speed of the operating frequency is 55 of the rated operating frequency.
In the range of% or less, the descending speed is 1/6 Hz / s
Explanatory drawing of the prior art example which showed the measurement result of the amount of contact when it was set to ec.

FIG. 9 is an explanatory diagram showing the measurement result of the contact amount of the present invention when the decreasing rate of the operating frequency is 1/9 Hz / sec or less.

FIG. 10: The descending speed of the operating frequency is 5 of the rated operating frequency
When it falls within the range of 5% or less, the descending speed is
Explanatory drawing which showed the measurement result of the contact amount at the time of making it slower than the descending speed to 55%.

[Fig. 11] The descending speed of the operating frequency is 5 of the rated operating frequency.
Explanatory drawing which showed the measurement result of the contact amount at the time of making the descending speed slower than the descending speed to 55% within the range of 5% or less.

FIG. 12 is a block diagram similar to FIG. 1, in which a control circuit for increasing the fan air volume of the condenser is provided for a certain period of time when the operating frequency is decreased.

FIG. 13 is an explanatory diagram showing the measurement result of the contact amount during the operation in which the fan air flow rate of the condenser is increased.

FIG. 14 is a block diagram similar to FIG. 1 in which a control circuit that throttles the expansion valve is provided for a certain period of time when the operating frequency is decreased.

FIG. 15 is an explanatory diagram showing a measurement result of a contact amount during operation in which the expansion valve is throttled for a certain period of time when the operation frequency is decreased.

FIG. 16 is an explanatory diagram showing a measurement result of a contact amount during operation in which the expansion valve is opened when the operation frequency is decreased.

FIG. 17 is a block diagram similar to FIG. 1 in which a hot gas bypass circuit is provided in the refrigerant circuit.

FIG. 18 is an explanatory diagram showing a measurement result of a contact amount during operation using a hot gas bypass circuit.

FIG. 19 is a block diagram similar to FIG. 1, which includes a circuit that enables reverse defrosting operation with a four-way valve when the operating frequency decreases.

FIG. 20 is an explanatory diagram showing the measurement result of the contact amount during the reverse defrosting operation when the operating frequency decreases.

FIG. 21 is a block diagram similar to FIG. 1 in which a release circuit for releasing discharge pressure is provided in the refrigerant circuit.

FIG. 22 is an explanatory diagram showing the measurement result of the contact amount during operation using the release circuit.

23 is a block diagram similar to FIG. 1, in which a refrigerant tank for reducing the discharge pressure is provided in the refrigerant circuit.

FIG. 24 is an explanatory diagram showing a measurement result of a contact amount when a refrigerant tank is used.

[Explanation of symbols]

1 compressor 3 Refrigerant circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Hayano 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Inside the Research Center for Living Space Systems, Toshiba Corporation (72) Hideaki Motohashi 8th Shin-Sugita-cho, Isogo-ku, Yokohama, Kanagawa TOSHIBA CORPORATION (56) References JP-A-7-190517 (JP, A) JP-A-60-181550 (JP, A) JP-A-7-120081 (JP, A) JP-A 63-123957 (JP, A) JP-A-4-9553 (JP, A) Actually developed 63-181768 (JP, U) Actually developed 62-173668 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 1/00 F24F 11/02

Claims (3)

(57) [Claims] 1. A compressor, an indoor heat exchanger, an outdoor heat exchanger,
HF that does not contain chlorine in the refrigerant with a throttle mechanism and a four-way valve
The refrigerant circuit in which C refrigerant is used and the output frequency is changed to
Frequency that variably controls the compressor from low speed to high speed
Number converter and room temperature and temperature of temperature setter detected by the sensor
Frequency setting signal to the frequency converter according to the difference
And a converter control device for controlling the frequency converter.
An air conditioner characterized in that when the wave number is changed to a low operating frequency, the descending speed of the operating frequency is controlled at 1/9 Hz / sec or less. 2. A compressor, an indoor heat exchanger, an outdoor heat exchanger,
HF that does not contain chlorine in the refrigerant with a throttle mechanism and a four-way valve
The refrigerant circuit in which C refrigerant is used and the output frequency is changed to
Frequency that variably controls the compressor from low speed to high speed
Number converter and room temperature and temperature of temperature setter detected by the sensor
Frequency setting signal to the frequency converter according to the difference
And a converter control device for controlling the frequency converter.
When changing from a wave number to a low operating frequency, if the falling speed of the operating frequency falls within the range of 55% or less of the rated operating frequency of the compressor , 55% of the rated operating frequency
An air conditioner characterized by being controlled at a descending speed slower than the descending speed up to. 3. In the refrigerant circuit, when the operating frequency decreases
According to claim 1 or 2, characterized in that it comprises a control circuit to lower the discharge pressure of the compressor at the previous stage to move to its lowered
Air conditioner.