JPS5819639A - Method of operating and controlling variable-capacity compressor in a refrigerating system - Google Patents

Abstract

PURPOSE:To improve the operation efficiency of a variable-capacity compressor for automobile air conditioning by switching between the values of the compressor capacity and turning on and off the compressor in accordance with one of the temperature, pressure, degree of overheat of intake and discharge gas and the temperature at an evaporator outlet air compared with a preset reference value. CONSTITUTION:When starting refrigerating, the compressor 2 starts operation with the capacity of about 50% in accordance with the intake gas pressure Ts and preset values Ts1 and Ts2, while it is switched to 100% capacity operation when the discharge valve is opened to a standard opening degree. As refrigerating goes on to decrease the intake gas temperature Ts and its pressure Ps reducing heat exchange efficiency, so that the Ts reaches Ts2, a control unit delivers a capacity decreasing signal to switch the co mpressor 2 to 50% capacityoperation. When furthermore the pressure drops to the lowest limit value Ps2, the control unit 17 delivers a signal to disengage the clutch allowing the compressor 2 to stop. When the pressure again rises to Ps1, 50% capacity operation takes place. With these step repeated, the operational efficiency of the variable-capacity compressor is improved during refrigerating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the operation of a variable capacity compressor, which is particularly suitable for vehicle air conditioning, and is capable of changing its working capacity depending on load conditions.

Conventionally, as a method for controlling the operation of a variable capacity compressor in a vehicle cooling system, a pressure sensor is used to measure the pressure of refrigerant gas that is sucked into the compressor after heat exchange by an evaporator installed in a duct, that is, the suction gas pressure. There has been a system in which a controller outputs a capacity down signal to a capacity switching mechanism of a compressor when the suction gas pressure falls below a set value with the passage of operating time.

(Unexamined Japanese Patent Publication No. 55-160187 by the same applicant) However, since the above-mentioned control method does not include ON/OFF control of the compressor, when the cooling load such as dehumidification is small and the cooling capacity is excessive even if the capacity is small, The problem with this was that the damper was opened to increase the amount of heating by the heater, doing extra work to heat up an area that was too cold, resulting in a large loss of power.

The purpose of the present invention is to switch the capacity of the compressor to a large capacity range when one of the suction gas pressure, suction gas temperature, suction gas superheat degree, or discharge gas superheat degree reaches a set value when the cooling load is large. When the cooling load is small, the suction gas pressure, suction gas temperature, suction gas superheat degree,
When either the superheat degree of the discharge gas or the evaporator outlet air temperature reaches the set value, the compressor can be operated in an efficient state by controlling the capacity of the compressor in a small volume range. An object of the present invention is to provide a method for controlling the operation of a variable capacity compressor in a cooling system that can reduce power loss.

Hereinafter, first to fourth embodiments in which the present invention is embodied as an operation control method for a variable capacity compressor for vehicle air conditioning will be described with reference to the drawings.

First, a general overview of the vehicle cooling system used in the control method of each embodiment will be explained with reference to FIG. 1.
is an engine, and 2 is a variable capacity compressor driven by this engine 1, and in this embodiment, the operating capacity is 50%.
It uses a swash plate type that can be switched to two stages: 100% and 100%. This compressor has one of the discharge valves for the discharge port connecting the front and rear side compression chambers and the discharge chamber.
The rear discharge valve is always held floating in the open position via a spring, and the discharge pressure of the refrigeration cycle is applied to the rear side of the discharge valve to maintain it in the normal closed position. It is equipped with a capacity switching machine 3. (For example, Japanese Patent Application No. 55-15129 filed by the same applicant)
(Refer to No. 8) In addition to this compressor, various types of compressors capable of steplessly changing the capacity in three or more stages may be used.

The discharge flange 4 and suction flange 5 of the compressor 2 include
A condenser 6, a receiver 7, an expansion pulp 8, and an evaporator 9 that constitute a refrigeration cycle are connected in series.

On the other hand, inside the duct 10, a fan 11, the evaporator 9, a damper 12, and a heater 13 using the cooling water of the engine 1 are sequentially arranged. The temperature of the air blown out from 14 can be adjusted to a desired temperature.

A pressure sensor 15 and a temperature sensor 16 are provided in the middle of the pipe connecting the evaporator 9 and the suction flange 5 to detect the pressure and temperature of the gas sucked into the compressor.

A controller 17 is connected between these pressure and temperature sensors 15 and 16 and the capacity switching mechanism 3, and in this embodiment, the pressure and temperature sensors 15, 16 and the capacity switching mechanism 3 are connected to each other. set pressure PB2 (e.g. 0.5 kg
/d) and the suction gas pressure PS detected by the pressure sensor 15, and when this suction gas pressure reaches the set value PS2, the operation circuit (path shown in the figure) of the controller 17 A capacity down signal is output to the capacity switching mechanism 3, and conversely, the suction gas pressure Ps changes to the set value PS.
A setting value Ps1 that is larger than 2 (for example, 3 to 9/l'4)
When this happens, a capacity up signal is output to the capacity switching mechanism 3.

Similarly to the relationship between the separate controller 17 and the pressure sensor 15, when the intake gas temperature TS detected by the temperature sensor 16 reaches the set temperature TS2 (for example, 2°C) preset by the controller 17, the A capacitance down signal is output from TS2, and conversely, the set value Tst(
For example, when the temperature reaches 10° C., a capacitance up signal is output.

Also 1. The controller 17 has a Morie Iv (P-i) determined by the suction gas temperature Ts and suction gas pressure Ps.
) degree of superheat at the suction state point in the diagram (superheat)
is stored, and this superheat degree Tsh is the set superheat degree Ts.
When the temperature below h2 (for example, 5°C) continues for a certain period of time h1, the controller 17 outputs a clutch OFF signal, and a setting higher than the set value 'r s h 2 [Tsh l (for example, 15°C) or more] is output. When the state continues for a certain period of time h1, the controller 17 outputs a clutch ON signal.

Although not shown, a pressure sensor and a temperature sensor for detecting the discharge pressure Pd and temperature Td are provided in the pipeline connecting the discharge flange 4 and the condenser 6. The controller 17
When the following state continues for a certain period of time hl in the Mollier diagram determined by the discharge pressure Pct and temperature Tcl, a clutch OFF signal is output from the controller 17, and a set value (lower than the set value Tdh2) is output. For example 40'C)
When the above state continues for a certain period of time, the controller 17 outputs a clutch ON signal.

Further, the controller 17 outputs a gas shortage signal and stops the compressor when the superheat degree Tsh of the suction gas reaches a set value Tsh8 (for example, 20°C) which is higher than the set value Tsh1. .

On the other hand, between the evaporator 9 and the damper 12, there is a temperature I of the air passing through the evaporator outlet. i
A temperature sensor 18 is provided to detect the evaporator outlet air temperature Te or simply referred to as outlet temperature Te hereinafter. When the evaporator outlet air temperature Te detected by the temperature sensor 18 reaches the set temperature Te2 (for example, 3°C), the controller 17 turns off the clutch.
A clutch ON signal ° is output when the set value Te1 (for example, 6° C.) is higher than the set value Te2.

Next, a first embodiment of the control method of the present invention will be described with reference to FIG. 2 based on the vehicle air conditioning cooling system configured as described above.

In this embodiment, when the cooling load is large, the compressor is reduced to 50% depending on the suction gas temperature TS, set values TSl, and TEt2.
and 100% capacity, and when the cooling load is small, the compressor is controlled to turn on, off, and at 0% and 50% capacity using the suction gas pressure Ps and the set value Pet, P82.

Now, when the electromagnetic clutch is turned on by the cooling device start switch (as shown), the compressor is started at 50% capacity.
Thereafter, when the discharge pressure increases and the discharge valve is moved to its normal closed position, it is driven at 100% capacity. The compressed refrigerant gas discharged from the discharge flange 4 is transferred to a condenser 6 and a receiver 7.
The pulp is then sent to the evaporator 9 via the expansion pulp 8, where the heat is exchanged by the desired air forcibly transferred by the fan 11, and then sucked into the compressor from the suction flange 5. The intake gas temperature Ts and pressure Ps gradually decrease as the operating time passes, but for a while after the clutch is turned on and the compressor is operated at 100%, the temperature inside the vehicle remains high. Since the cooling load is large and heat exchange is performed efficiently, the temperature Ts and the pressure PS drop rapidly. After that, as the cabin temperature decreases and the heat exchange efficiency decreases, the decrease in temperature Ts and pressure Ps becomes gradual, and when the temperature TS reaches the set temperature TS2, a capacity down signal is output from the controller 17. Then, the capacity switching mechanism 3 is activated, and the compressor is switched from 100% to 50% operation.

Even if the capacity is reduced in this way, if the cooling capacity of the compressor is somewhat large, the suction gas temperature, pressure Ts, and Ps will all decrease as shown by the solid line in Figure 2, and when the pressure Ps reaches the set pressure PS2, it will stop. A clutch OFF signal is output from the controller 17, and the compressor that is operating at 50% is stopped. After that, when the pressure PS increases and reaches the set pressure PS1, the compressor temperature TS is not at the set value TS1, so the temperature TS is 50%
It is operated at the capacity, and thereafter the capacity is alternately switched between 0% and 50% in the same manner.

On the other hand, when the compressor capacity is reduced to 50% and the cooling capacity is insufficient, the suction gas temperature TS and pressure ps rise as shown by the dashed line in Figure 2, and when the temperature Ts reaches the set value TSI. The compressor is switched from 50% to 100% capacity. After that, set value TS2. 5 by T81
Capacity switching between 0% and 100% is performed alternately.

By the way, between the intake gas temperature TS and the pressure psO,
Since the degree of superheating TSh is specified on the Mollier diagram, if the temperature TS is determined, the pressure Ps is also determined, and the set value T
Assuming that the pressure at S2 is PB, PS2<PB is set between this pressure PB and the set value P8'2 so that the compressor does not go from 100% capacity to 0% capacity all at once. Further, assuming that the pressure determined by the set value TS1 is PA, PS 1 <PA is set so that the compressor is started at 50% capacity when the clutch is turned on.

Now, in the first embodiment of the present invention, when the cooling load is small, the compressor is turned on and off at 0% and 50% capacity depending on the suction pressure Ps, set value Psx, and PS2, so that excessive cooling can be prevented by using the heater. By eliminating the extra work of heating, the compressor can be operated efficiently according to the cooling load, and since two types of sensors are used, one for pressure and one for temperature, the hysteresis of these sensors is reduced by 7. ) It is possible to use an inexpensive ON/OFF' type, and it is possible to reduce costs.

In addition, in this first embodiment, the intake gas temperature TS is T
If the gas shortage signal is output when the pressure becomes S1 or more, or when the pressure Ps becomes less than PS2, it can also be used as a gas shortage sensor.

Next, a second embodiment of the control method of the present invention will be described with reference to FIG.

In this embodiment, when the cooling load is large, the suction gas pressure PS and the set values Psi and PS2 are set at 50% and 100%.
When the cooling load is small, O% and 5 are changed depending on the intake gas temperature TS and set values T81 and TS2.
0% ON-OFF control is performed, and when the pressure ps reaches the set value PS2, the pressure 'm machine is switched from 100% to 50% capacity. When the cooling capacity is slightly large in the capacity down state, the pressure Ps and temperature Ts decrease as shown by the solid line in Figure 3, and when TS reaches the set value TS2, the clutch is turned off and the compressor, which is operating at 50%, is stopped. Ru. After that, when the temperature TS rises and reaches the set value TS1, the clutch is turned on, but the pressure Ps increases to the set value 11 IPS.
Since the set value Tl32. The TSI performs ON-OFF control of the compressor at 0% and 50% capacity.

On the other hand, when the capacity of the compressor is reduced from 100% to 50% and the cooling capacity is insufficient, the gas pressure Ps rises sharply as shown by the dotted chain line in Figure 3.

When the temperature T6 rises and the pressure Ps reaches the set value Pss, the capacity of the compressor is increased from 50% to 100%, and then the set value PS2. Capacity switching between 50% and 1'OO% is performed alternately by Psi.

In this second embodiment as well, the set value TS
Let PB be the suction pressure determined by 2, in order to prevent the compressor from going from 100% power to 0% valley volume VC all at once, set PS2'>PB, and set the set value TS1.
Let PA be the suction gas pressure determined by Psi>PA so that the compressor is started at 50% capacity.

In this second embodiment, when the cooling load is small δ, the suction waste temperature TS and the set value TS'2' are 0% and 50% depending on the TSI.
% 0N-OFF control, the compressor can be operated efficiently according to the cooling load as in the first embodiment described above, and the pressure and temperature sensor 1 can be operated efficiently.
Both of 5 and 16 can be inexpensive ON-OFF types with large hysteresis, which can reduce costs.

The pressure sensor 15 is of a type capable of continuous output, and when the suction gas pressure Ps is a set value Psa smaller than the set value Psg and the suction gas temperature TS is higher than the set value Tst, or the temperature sensor 16 is If the type is configured to be able to output continuously, and the gas shortage signal is output when the suction gas temperature Ts is set at a set value TS8' which is higher than the set value Tel, and the suction pressure Ps is below the set value PS2, gas shortage can be detected. can be detected.

Next, a third embodiment of the control method of the present invention will be described with reference to FIG.

In this embodiment, when the cooling load is large, the capacity is switched between 50% and 100% depending on the suction pressure Ps, and when the cooling load is small, the capacity is switched between 50% and 100% depending on the superheat degree Tsh of the suction gas.
The clutch is turned on and off at 50% capacity, and as cooling progresses and the suction pressure ps reaches the set value PS2, the capacity is reduced from 100% to 50%. In this state, when the cooling capacity is slightly large, the suction pressure Ps and the degree of superheat TSh gradually decrease, and when the degree of superheat Tsh remains below the set value Tsh2 for a certain period of time, the clutch is turned OFF and the compressor operates at 50%. will be stopped. After that, the superheat degree Tsh increases by J% and the set value Tsh
If the state of 1 or more continues for a certain period of time h1, the clutch will turn ON.
However, since the pressure Ps has not reached the set value Psl, the compressor is operated at 50% capacity. Thereafter, similarly, the compressor is turned off alternately at 0% and 50% capacity according to the set values Tsh2, 'rsht, and ht.

On the other hand, if the compressor capacity is reduced from 100% to 50% and the cooling capacity is insufficient, the suction pressure Pa will be reduced to the 4th level.
The pressure increases as shown by the dashed line, and when this pressure Ps reaches the set value P81, the capacity increases from 50% to 100%.
Similarly, set value PS2. (by Pal) 50% and 1
00% capacity switching is performed alternately.

In addition, the degree of superheating Tsh of the intake gas is abnormally large T...
When S h a is exceeded, a gas shortage signal is output.

By the way, since the suction gas is in motion while the compressor is operating, the suction gas temperature T is constant regardless of the mounting position of the temperature sensor 16.
However, when the compressor is once stopped, the closer the temperature sensor is to the compressor, the more likely it is to be affected by the heating. Therefore, the suction gas temperature TS of the second embodiment
Alternatively, if the clutch is turned on by detecting the superheat degree Tsh determined by the temperature TS as in the third embodiment, reliable control will be hindered. Therefore, it is desirable to install the clutch away from the compressor to a position where the influence of differences in mounting location can be ignored, or to control ON/OFF of the clutch according to the first embodiment using the suction gas pressure ps. It is also possible to turn on the clutch when the pressure Ps reaches the fourth set value PS8.

Like the first and second embodiments described above, this third embodiment also enables efficient compressor operation according to the cooling load, and also enables pressure and temperature sensors to be turned on and off.
It is possible to reduce costs by using an inexpensive formula.

Next, a fourth embodiment of the control method of the present invention will be described with reference to FIG.

In this case, the suction gas pressure Ps is 50% and 100%.
The evaporator outlet air temperature T
Clutch ON/OFF control is performed with po% and 50% capacity by e, and the suction pressure Ps is the set value PS.
2, the capacity is reduced from 100% to 50%, and in this state, when the cooling capacity is slightly large, the suction pressure Ps and outlet temperature Te of K will decrease, and when the same temperature Te' reaches the set value Te2, the clutch will be turned off. A compressor running at 50% is shut down. After that, the outlet temperature Te rises to the set value Tel.
When this happens, the clutch is turned on and the pressure Ps reaches the set value PS1.
Since this is not the case, the compressor is operated at 50% capacity, and the compressor is similarly operated alternately at 0% and 50% capacity based on the set value Te5Tel.

On the other hand, when the compressor capacity is reduced from 100% to 50% and the cooling capacity is small, the suction pressure Ps and the outlet temperature Te increase, and the pressure Ps becomes the set value Ps IIC
Then, the capacity will be increased from 50% to 100%, and the setting value PS2. Psi alternately switches the capacity between 50% and 100%.

Note that when the suction pressure PS is less than PS2 and the outlet temperature Te
is higher than the set value Tel (for example, 2
0℃), a gas shortage signal is output, the compressor at 50% operation is turned off, and then the pressure Ps returns to the set value P.
It is also possible to prevent it from turning ON even if it returns to 82 or higher.

The control method of this fourth embodiment is similar to the above-mentioned mini and second embodiments, in that it is possible to operate the compressor efficiently according to the cooling capacity, and it is also possible to reduce the cost of pressure and temperature sensors. Since the clutch is CUFFed when the evaporator outlet temperature Te reaches the set value Te2, it is possible to prevent the evaporator from frosting.

Note that the present invention can also be embodied in the following embodiments.

To change the capacity of the compressor, including a step of changing the capacity of the compressor to another capacity smaller than the one described above, instead of ON-OFF control of the compressor.

When the cooling load is large, the suction gas pressure Ps.

When any one of the suction Ganu temperature Ts, suction gas superheat degree TSh, or discharge gas superheat degree Tdh reaches a set value, the capacity of the compressor is switched in the large capacity range, and when the cooling load is small, the pressure Ps is changed. .

When any one of the temperature TS, superheat degree Tsh, Tdh, or evaporator outlet temperature Te reaches the set value, compressor capacity switching or clutch ON-OF occurs in the small capacity range.
Try to do F.

As detailed above, in the present invention, when the cooling load is large, the capacity is switched in the large capacity range, and when the cooling load is small, the capacity is switched in the small capacity range.
This has the effect of eliminating the extra work of heating up overly cooled areas and allowing efficient compressor operation according to the cooling load.

[Brief explanation of the drawing]

FIG. 1 is a road body plan view showing an embodiment of the cooling device used in the control method of the present invention for vehicle air conditioning, and FIGS. 2 to 5 are the first embodiment of the control method of the present invention. - It is a graph explaining a fourth example. Variable capacity compression @2. Capacity switching mechanism 3. Pressure sensor 15.
Temperature sensors 16, 18. Controller 17. Suction (discharge) gas pressure Ps (Pd), suction (discharge) gas temperature Ts (Td)
, degree of superheating of the suction (discharge) gas T's h (Tdh)
Evaporator outlet air temperature Te, set value P B j
, P S 2 , T, , s 1 , T B 2
. Tsht, T! 3h2. T(lhl, TCLh2
, Tel, Te2. Time h1゜

Claims (1)

[Scope of Claims] 1 Compressed gas is sent to the refrigeration cycle from a variable capacity compressor whose capacity, or cooling capacity, can be switched and adjusted according to the cooling load by a capacity switching mechanism to perform cooling action, and then heat exchange is performed. In the cooling method in which the gas that has finished the process is sucked into the compressor again, ■ suction gas pressure Ps of the compressor ■ suction gas temperature Ts of the compressor ■ suction gas determined by the suction gas pressure Ps and temperature Ts Superheat degree Tsh ■ Superheat degree T of the discharge gas determined by the discharge gas pressure Pd and temperature Td of the compressor (lh Preset settings corresponding to any one of the above ■ to ■ and each of ■ to ■ When one of the values from ■ to ■ becomes the set value, the operating means operates a capacity switching mechanism to switch and control the capacity of the compressor; ■
The evaporator outlet air temperature Te is compared with any one of the above ■ to ■ and the nine preset values set in advance corresponding to each of ■ to When the value reaches the set value, the operating means turns on and off the compressor clutch.
1. A method for controlling the operation of a variable capacity compressor in a cooling device, characterized in that the variable capacity compressor is operated. 2 When the cooling load is large, the capacity of the compressor is switched between 50% and 100% according to the suction gas temperature Ts and the set value TS2・Tel, and when the cooling load is small, the compressor is switched between 50% and 100% capacity according to the suction gas pressure Ps and the set value Ps2・P81. A method for controlling the operation of a variable capacity compressor in a cooling device according to claim 1, wherein the variable capacity compressor is turned off at 0% and 50% capacity. 8 When the cooling load is large, the intake gas pressure PS and set value Ps2. The capacity of the compressor is switched between 50% and 100% capacity using Pst, and when the cooling load is small, the compressor is switched to 0 depending on the suction gas temperature Ts and the set value TS2゜TSl.
A method for controlling the operation of a variable capacity compressor in a cooling system according to claim 1, wherein the variable capacity compressor is turned on and off at 50% and 50% capacity. 4 When the cooling load is large, the suction gas pressure Ps and the set value ps2. The capacity of the compressor is switched between 50% and 100% capacity using ps-t, and when the cooling load is small, the suction gas superheat degree Tsh and the set value TSh2. A method for controlling the operation of a variable capacity compressor in a cooling system according to claim 1, wherein the compressor is turned off at 0% and 50% capacity by TShl. 5 When the cooling load is large, set the suction gas pressure ps @PB2. : The capacity of the compressor is switched between 50% and 100% capacity using PB1, and when the cooling load is small, the evaporator outlet air temperature Te and the set value Te2. Tel
A method for controlling the operation of a variable capacity compressor in a cooling device according to claim 1, wherein the variable capacity compressor is turned on and off at 0% and 50% capacity.