JP2701415B2 - Expansion valve control unit for refrigerator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve control device for a refrigerator, which controls a flow rate of a refrigerant in a refrigeration cycle.

[Conventional technology]

2. Description of the Related Art Conventionally, as an expansion valve control device for a refrigerator, an electromagnetic expansion valve control device having excellent responsiveness, in which a valve element of an expansion valve is electrically controlled by an actuator or the like, is known.

[Problems to be solved by the invention]

However, in this conventional electromagnetic expansion valve control device, there is a problem of vibration and noise caused by driving the actuator. In addition, assuming that the vibration and noise are small, the temperature-sensitive cylinder is thermally connected to the outlet pipe of the evaporator, and the diaphragm is driven through the pressure medium in the temperature-sensitive cylinder and the temperature-actuated valve that is connected to the diaphragm is driven. An expansion valve control device of the type is known, but has a problem of poor response.

The present invention has been made in view of the above problems, and has as its object to provide an expansion valve control device for a refrigerator having excellent responsiveness and capable of reducing vibration and noise.

[Means for solving the problem]

In order to solve the above object, in the present invention, the diaphragm is displaced in accordance with the pressure of the pressure medium sealed in the temperature-sensitive member, and the opening degree of the valve body connected to the diaphragm is controlled to evaporate. In a refrigerator expansion valve control device for controlling the flow rate of refrigerant flowing into the evaporator so that the heating degree of the evaporator matches the target heating degree of the evaporator, the heating degree of the evaporator is electrically controlled. Detecting means for detecting; control means for matching the degree of heating of the evaporator electrically detected by the detecting means with the target degree of heating of the evaporator; and a pressure sealed in the temperature-sensitive member. Pressure increasing means for electrically increasing the pressure of the medium, the pressure of the pressure medium corresponding to the target degree of heating of the evaporator, and the pressure of the pressure medium sealed in the temperature-sensitive member,
Technical means is provided that includes pressure reducing means for electrically lowering the pressure of the pressure medium corresponding to the target degree of heating of the evaporator.

Further, in the invention according to claim 2, the diaphragm is displaced in accordance with the pressure of the pressure medium sealed in the temperature sensing member, and the opening degree of the valve body connected to the diaphragm is controlled to control the evaporator. In a refrigerating machine expansion valve control device for controlling a flow rate of a refrigerant flowing into an evaporator so as to match a physical quantity corresponding to the pressure of the inlet refrigerant with a physical quantity corresponding to a target pressure of the inlet refrigerant of the evaporator, Detecting means for electrically detecting a physical quantity corresponding to the pressure of the refrigerant at the inlet of the evaporator; and a physical quantity corresponding to the pressure of the refrigerant at the inlet of the evaporator electrically detected by the detecting means. Control means for matching the physical quantity corresponding to the pressure of the refrigerant at the inlet of the evaporator; and controlling the pressure of the pressure medium sealed in the temperature-sensitive member with respect to the physical quantity corresponding to the target pressure of the refrigerant at the inlet of the evaporator. Pressure increasing means for electrically increasing the pressure of the corresponding pressure medium, and the pressure of the pressure medium sealed in the temperature sensing member,
And a pressure reducing means for electrically lowering the pressure of the pressure medium corresponding to a physical quantity corresponding to the target pressure of the refrigerant at the inlet of the evaporator.

[Operation] In the present invention configured as described above, the heating degree of the evaporator electrically detected by the detecting means and the target heating degree are adjusted by the pressure increasing means so as to be matched by the control means. The pressure of the pressure medium sealed in the temperature-sensitive member is increased, or the pressure of the pressure medium sealed in the temperature-sensitive member is reduced by pressure reducing means. The pressure of the pressure medium sealed in the temperature-sensitive member acts on the diaphragm, and when the pressure of the pressure medium increases, the valve body connected to the diaphragm opens to increase the amount of the refrigerant flowing into the evaporator. When the pressure of the medium decreases, the valve body connected to the diaphragm closes, and the amount of the refrigerant flowing into the evaporator decreases.

The same effect can be obtained by using a physical quantity corresponding to the pressure of the refrigerant at the inlet of the evaporator instead of the degree of heating of the evaporator.

〔Example〕

Hereinafter, the present invention will be described based on an embodiment shown in the drawings.
FIG. 1 is a diagram in which a first embodiment of the present invention is applied to a vehicle cooling device. 1 is an electromagnetic clutch 3 according to a vehicle engine.
5 is a condenser, 7 is its cooling fan, 9 is a receiver, 11 is an expansion valve, 13 is an evaporator, 15
Is an electric blower that sends cool air into the vehicle interior, 17 is a first temperature sensor that detects the temperature of the refrigerant at the inlet of the evaporator 13, 19 is a second temperature sensor that detects the temperature of the refrigerant at the outlet of the evaporator 19, It comprises a thermistor, 21 is a control circuit, 23 is a manually operated switch installed at an appropriate position in the vehicle interior, 24 is an economy switch, and 25 is a vehicle battery.

FIG. 2 shows an expansion valve 11, an evaporator 13, temperature sensors 17, 19,
3 is a drawing showing a detailed relationship of the control circuit 21, wherein a valve element 30 is closed by the force of a spring 32. The first and second temperature sensors 17 and 19 are provided on the outer surfaces (or inside the pipes) of the evaporator inlet pipe 40 and the evaporator outlet pipe 41, respectively.

The valve body 30 is connected to the diaphragm. The internal space a reaching the upper part of the diaphragm, the capillary, and the thermosensitive cylinder are filled with the same saturated gas refrigerant as the refrigerant in the refrigerating device. The capillary 35 is a thin metal tube made of copper or the like, and is thermally connected to an evaporator inlet pipe 40 made of aluminum or the like downstream of the expansion valve 11 by a heat conduction block 42 made of metal such as aluminum. The equalizing pipe 38 is connected to the evaporator inlet pipe 40.
This is a tube for equalizing the pressure on the lower side of the diaphragm 34 and the pressure on the lower side of the diaphragm 34 so that even if the pressure suddenly changes due to a sudden load fluctuation of the refrigeration cycle, the tube can follow the pressure.

3 (a) and 3 (b) are diagrams showing a detailed configuration near the temperature sensing cylinder 36, and FIG. 3 (b) is a diagram showing FIG. 3 (a).
It is AA sectional drawing of. The temperature sensing tube 36 is press-fitted into the heat conduction block 42, and the evaporator inlet pipe 40 is fixed by a clip 44 made of a metal spring material in a state where the evaporator entrance pipe 40 is in contact with the heat conduction block on the upper flat surface.

A terminal 46 and a temperature-sensitive element (in this embodiment, a positive temperature coefficient thermistor (hereinafter, referred to as a PTC heater) made of a barium titanate-based ceramic semiconductor), and 48 are provided in the heat conduction block 42 shown in FIG. It is fitted into the recess, and is further fixed thereon with a clip 44. In addition, PTC heater 4
There are electrodes (not shown) on both surfaces of 8, and one of them is electrically connected to the terminal 46. The contact portion between the terminal 46, the clip 44, and the heat conduction block 42 is electrically insulated by enamel or the like. Further, as shown in FIG. 3 (b) or FIG. 3 (d), the shape of the heat conduction block 42 is as follows.
A narrow portion D is provided between the PTC heater 48 and the evaporator inlet pipe 40 to reduce the amount of heat generated by the PTC heater 48 being taken by the evaporator inlet pipe 40.

Next, the variable capacity compressor 1 will be described with reference to FIG. The housing 111 made of an aluminum alloy has a plurality of cylinder spaces 113 formed therein in parallel with each other. A pressure chamber housing 115 is provided on a side surface of the housing 111, and a shaft 117 is rotatably supported by the pressure chamber housing 115 and the housing 111.
That is, the bearing 119 is press-fitted into the housing 111, and this bearing 11
The shaft 111 is rotatably supported by 9. shaft
The other end of 117 is rotatably supported by bearing 121.

Further, a shaft seal 123 is provided between the shaft 117 and the pressure chamber housing 115, and the refrigerant and the lubricating oil in the pressure chamber 125 are provided by the shaft seal 123.
Leakage to the outside along the outer periphery of the shaft 117 is prevented. A pin guide 127 is fixed to the shaft 117, and the pin guide 127 rotates integrally with the shaft 117. A pin 129 is connected to the pin guide 127, and the wobble 131 is connected to the pin guide 127 by the pin 129. Therefore, a bearing 133 is provided on one surface of the wobble 131, and the swash plate 135 is provided through the bearing 133.
Are held in a rotatable state. Therefore, wobble
Of the rotational oscillating motion of 131, the rotational motion is escaped by bearing 133, and swash plate 135 performs only oscillating motion in pressure chamber 125. The swinging motion of the swash plate 135 is connected to the piston 139 via the connecting rod 137.

The piston 139 is provided to be reciprocally slidable in the cylinder 113. On the back surface of the piston 139, a connecting recess 141 is formed.
Seven balls 143 at the tip are provided. Note that the ball 143 is held by the holding plate 145. A ball 147 is also formed at the other end of the connecting rod 137.
The swash plate 135 is rotatably held by the swash plate 135 via the swash plate 9.

Here, since the wobble 131 is connected by the pin 129, the wobble 131 can be inclined with respect to the shaft 117. Therefore, the inclination angle of inclination 135
It is made variable according to the inclination angle fluctuation of 31. The change in the tilt angle of the tilt 135 results in a change in the reciprocating stroke of the piston 139. Note that a support rod 151 is provided between the housing 111 and the pressure chamber housing 115 so that the swash plate 135 performs only a swinging motion and does not perform a rotating motion. The support bar 151 is slidably engaged with the connecting portion 153 of the swash plate 135, so that the swash plate 135 only moves along the support bar 151.

In addition, connection holes 155 are formed in the outer peripheral surfaces of the housing 111 and the pressure chamber housing 115, respectively, and the compressor 1 is directly fixed to an automobile driving engine via the connection holes 155.

At one end of the housing 111, a side plate 157 is provided, and further outside the side plate 157,
A side housing 159 is provided. In the side housing 159, a suction chamber 161 and a discharge chamber 163 are formed. The suction chamber 161 communicates with the cylinder 113 via a suction hole 165 formed in the side plate 157. Suction hole
A suction valve 166 is provided on the cylinder 113 side of the
Only the flow of the refrigerant from 61 to the cylinder 113 is allowed.

The discharge chamber 163 has discharge holes formed in the side plate 157.
It communicates with the cylinder 113 via 167. A discharge valve 169 is disposed on the discharge chamber 163 side of the discharge hole 167, and allows only the flow of the refrigerant from the cylinder 113 to the discharge chamber 163.

The suction chamber 161 receives the refrigerant from the evaporator 13, and the discharge chamber 163 supplies the refrigerant to the condenser 5.

Inside the side housing 159, there is also a Velofram storage room 1
The bellows storage chamber 171 accommodates a bellows 175 of a superheat valve (hereinafter, referred to as SH valve) 173. Belofram 175 is ball valve by operating rod 177
Connected to 179. This ball valve 179 is located in the intermediate chamber 181.

A coil spring 182 is housed in the bellofram 175, and the same refrigerant as the refrigerant of the refrigeration cycle (if cooled, Freon R-1)
2) is enclosed in a saturated state. Belofram storage room 1
The inside of 71 is under the same refrigerant pressure as the suction chamber 161 and the evaporator 1
When the degree of superheat (SH) of the refrigerant from 3 rises, Velofram 1
The pressure in the bellofram 175 relatively rises by the amount of the rise of the refrigerant in the refrigerant 75 due to the degree of superheat. That is, the ball valve 179 moves up and down along the drawing due to the expansion and contraction of the bellows 175, which expands and contracts according to the degree of superheat (SH).
The opening degree of the communication hole 183 between the discharge chamber 163 and the intermediate chamber 181 is controlled. The intermediate chamber 181 communicates with the pressure chamber 125 through communication holes 185, 187, and 189. Further, the pressure chamber 125 communicates with the belofram storage chamber 171 through the communication hole 191.

Note that an electromagnetic clutch 193 is connected to the shaft 117, and interrupts transmission of the engine output in response to a signal from the outside.

The operation of the variable capacity compressor 1 configured as described above will be described. When the electromagnetic clutch 3 is connected by an external signal, the rotational driving force of the engine is transmitted to the shaft 117 via the electromagnetic clutch 3. With the rotation of the shaft 117, the wobble 131 performs a rotational swinging motion, and the swash plate 135
Performs a rocking motion. The swinging motion of the swash plate 135 is
The force is transmitted to the piston 139 via 37, and the piston 139 reciprocates in the cylinder 113.

In accordance with the reciprocating motion of the piston 139, in the piston suction process, the suction valve 166 is pushed open, and the low-pressure refrigerant in the suction chamber 161 is sucked into the cylinder 113 through the suction hole 165. In the compression stroke of the piston 139, the refrigerant in the cylinder 113 is compressed, and when the pressure becomes equal to or higher than a predetermined pressure, the refrigerant opens the discharge valve 169 and is discharged from the discharge hole 167 to the discharge chamber 163. The high-pressure refrigerant discharged into the discharge chamber 163 is then guided to the condenser 5.

The displacement of the compressor 1 is made variable by changing the inclination angle of the swash plate 135. This inclination angle varies according to the pressure in the pressure chamber 125. That is, when the pressure in the pressure chamber 125 increases, the pressure applied to the back surface of the piston 139 also increases, and as a result, the piston 139 does not retreat much from the top dead center. When the pressure in the pressure chamber 125 increases as described above, the swash plate 1
The inclination angle of 35 becomes smaller, and the reciprocating stroke of piston 139 also becomes smaller.

The pressure control in the pressure chamber 125 for making the stroke variable is performed by the operation of the SH valve 173 described above. When the degree of superheat (SH) of the refrigerant from the evaporator 13 to the compressor 1 decreases, that is, when the refrigerant temperature decreases or the refrigerant pressure increases, the internal pressure of the bellofram 175 decreases or the external pressure increases. Rises to belofram 17
After five contractions, the ball valve 179 moves downward in FIG. as a result,
The amount of communication between the discharge chamber 163 and the pressure chamber 125 increases, and the pressure chamber 125
, The discharge capacity of the compressor 1 becomes small.
At this time, the communication hole 191 serves as a throttle to prevent the pressure in the pressure chamber 125 from immediately dropping to the low pressure side.

Conversely, when the degree of superheat (SH) increases, that is, when the temperature rises or the pressure falls, the internal pressure of the bellofram 175 increases or the external pressure decreases, causing the bellofram 175 to expand and the ball to expand. The valve 179 moves upward. As a result, the amount of communication between the discharge chamber 163 and the pressure chamber 125 decreases or is completely closed. At this time, the communication hole 191 releases the pressure in the pressure chamber 125 to the low pressure side, so that the pressure in the pressure chamber 125 decreases and the discharge capacity of the compressor 1 increases.

Next, the overall operation of the embodiment having the above configuration will be described. When the switch 23 is turned on, the control circuit
The electromagnetic crack 3 is connected by the signal from 21 and the compressor 1 is driven by the engine of the vehicle to compress the refrigerant. In addition, the cool air cooled by the evaporator 13 is blown into the vehicle interior by the electric blower 15. In this embodiment, when the cooling load of the refrigeration cycle is small, the superheat control is performed by the compressor 1 and the pressure control is performed by the expansion valve 11. However, the cooling load of the refrigeration cycle is large and the compressor 1 is operated at 100% capacity. When this is done, superheat control is performed in the expansion valve 11.

In the expansion valve 11, the saturated gas refrigerant sealed in the temperature-sensitive cylinder 36 is condensed in the temperature-sensitive cylinder 36 having the lowest temperature, so the saturation pressure corresponding to the temperature-sensitive cylinder temperature is applied to the upper part of the diaphragm 34 of the expansion valve 11. Can be transmitted to the diaphragm 34
And the opening degree of the valve body 30 is adjusted to control the refrigerant flow rate. Further, the temperatures of the inlet refrigerant and the outlet refrigerant of the evaporator 13 are detected by the first and second temperature sensors 17 and 19, and the detection signals are sent to the control circuit 21, and a predetermined calculation described later is performed. Thereafter, heating and cooling of the temperature-sensitive cylinder 36 are performed based on the calculation result. As a result, the diaphragm 34 is displaced, and the flow rate of the refrigerant is adjusted.

The control circuit 21 includes a microcomputer that executes a predetermined arithmetic process, receives signals from the first and second temperature sensors 17, 19, the switch 23, and turns on the electromagnetic clutch 3 of the variable displacement compressor 1; In addition to performing off control, on / off control of a PTC heater 48 described later is performed. In addition, evaporator 1
3. Other parts of the refrigeration cycle such as the variable capacity compressor 1 are the same as those shown in FIG.

The operation of the above configuration will be described with reference to the operation flowcharts shown in FIGS. 5 to 7.

When the switch 23 is turned on, the control circuit 21 starts the arithmetic processing shown in FIG. 5, starts the timer in step 500, and in step 501, the voltage V ₁ applied to the PTC heater 48.
It was set to 12V, setting the voltage V ₂ applied to the PTC heater 48 at step 502 to 0V.

Thereafter, the first temperature determination level t ₀ for selecting the superheat control and pressure control described later at step 503 3.5 ° C.
, And in step 504, the first and second temperature data t ₁ , t _{2 based on} the signals from the first and second temperature sensors 17 and 19.
Enter In the next step 505, the first temperature data t
₁ is equal to or first temperature determination level t ₀ or more. When the cooling load is large, the first temperature data t ₁ becomes equal to or higher than the first temperature determination level t ₀ , the determination in step 505 becomes YES, and the routine proceeds to the superheat degree control calculation routine 600. The temperature data t ₁ first when cooling load is small first
Becomes smaller than the temperature determination level t _0, the determination in step 505 becomes NO, and the process proceeds to the constant pressure control operation routine 700.

In the superheat control calculation routine 600, step 6 in FIG.
In step 01, the difference between the first and second temperature data t ₂ and t ₁ , that is, superheat degree data Δt indicating the degree of superheat is calculated. In step 602, it is determined whether the superheat degree data Δt is 10.5 ° C. or more. judge. If the superheat degree data Δt is a value of 10.5 ° C. or more, the VTC is supplied to the PTC heater 48 in step 603 to reduce the superheat degree.
₁ Apply (12V). As a result, the gas pressure in the capillary 35 and the temperature sensing tube 36 increases, the flow rate of the refrigerant from the expansion valve 11 increases, and the degree of superheat decreases. Subsequently, in step 604, the first and second temperature data t ₁ and t ₂ are input, and in step 605, it is determined whether the first temperature data t ₁ is equal to or higher than the first temperature determination level t _0. I do. The first temperature data t ₁ is at a first temperature determination level data t ₀ or more, still when superheat degree control is required the decision is YES, step 606
Is used to calculate the superheat degree data Δt. Then the program proceeds to step 607, sets the V ₁ when I passed timer that is started is more than 180 seconds in step 50 6V, the V ₂ to 3V, V ₁ If not elapsed 180 seconds 12V, V ₂ Is left at 0V. As a result, the PTC heater 48
Electricity is supplied at 0V and 12V to speed up the response. And 180 seconds after the start of the refrigeration cycle, the PTC heater
The energization to 48 is switched between 3V and 6V to ensure the stability of the refrigeration cycle.

Thereafter, the process proceeds to step 608, where the overheat ° C data Δt is set to 9.5.
It is determined whether the temperature is at least ° C. Superheat data Δt is 9.
When the temperature is 5 ° C. or more, it is determined that the degree of superheat still needs to be reduced, and the determination is YES, and the process returns to step 603 to repeat the above processing.

When the flow rate of the refrigerant is increased by the energizing operation to the PTC heater 48, the superheat degree is reduced, and the superheat degree data Δt becomes a value lower than 9.5 ° C.
Proceeding to 09, the voltage applied to the PTC heater 48 is set to V ₂ (0 V). Then, in steps 610, 611, 612, the previous step 60
Performs the same processing as 4,605,606, in step 613, the setting step 607 Similarly, the V ₁ when I passed timer started in the step 500 is more than 180 seconds 6V, 2 ₂ to 3V, passes 180 seconds V ₁ was 12V, V ₂ If not is by leave 0V, the response of 180 seconds after the refrigeration cycle starts, after elapse of 180 seconds and an emphasis on stability.

Thereafter, the process proceeds to step 614, where the superheat degree data Δt is 10.
Judge whether the value is 5 ° C or more. Superheat data Δ
The above processing is repeated while t is a value lower than 10.5 ° C.
The power supply to the PTC heater 48 is stopped, and the low-temperature refrigerant temperature from the evaporator inlet pipe 40 is transmitted to the temperature-sensitive cylinder 36 to reduce the temperature, and as a result, the refrigerant flow rate from the expansion valve 11 is reduced, Try to increase superheat. The reason why the temperature of the refrigerant flowing through the evaporator inlet pipe 40 is low is that the refrigerant has been decompressed and expanded by the expansion valve 11. Superheat rises,
When the superheat degree data Δt becomes a value of 10.5 ° C. or more, step 61
The determination at 4 is YES, and the heater energizing operation after step 603 is restarted.

Therefore, in the superheat control arithmetic routine 600, the first
As long as the temperature data t ₁ is equal to or higher than the first temperature determination level t ₀ , it is determined that superheat control needs to be performed, and the power supply of V ₁ and V ₂ to the PTC heater 48 is repeated to reduce the superheat. The value shall be ± 0.5 ° C with 10 ° C as the center.

On the other hand, when the cooling load is small and the determination in step 505 is NO, the cooling load is reduced by the processing of the superheat degree control calculation routine 600, and the step 605 or 611 is performed.
Is NO, the routine proceeds to a constant pressure control calculation routine 700 shown in FIG. In this constant pressure control operation routine 700, first in step 701 a first temperature data t ₁ is _{(t 0 -1 ℃) + 0.5} ℃, 3 ℃ or more because it is set in this case t ₀ = 3.5 ° C. Is determined. When the first temperature data t ₁ is not less than 3 ° C., the determination of step 701 is to YES, carry out the energization of 3V to the PTC heater 48 proceeds to step 702. Then, enter the first temperature data t ₁ proceeds to step 703, the first temperature data t ₁ compared to the first temperature determination level t ₀ the process proceeds to step 704, is the determination
If NO, the process proceeds to step 705 and the first temperature data t ₁
Is compared with (t ₀ −1 ° C.) − 0.5 ° C. (a value corresponding to 2 ° C. when t ₀ = 3.5 ° C.). Becomes YES determination in step 705 when the first temperature data t ₁ is 2 ℃ or more values, steps 70
Returning to step 2, energize the PTC heater 48 with 3V. This PT
By energizing the C heater 48, the flow rate of the refrigerant from the expansion valve 11 increases, and the temperature of the refrigerant in the evaporator inlet pipe 40 decreases. Then, when the first temperature data t ₁ becomes a value lower than 2 ° C. due to the decrease in the refrigerant temperature, the determination in step 705 becomes N
In step S706, the flow advances to step 706 to supply 6 V to the PTC heater 48. Then, the same process as in step 703 and 704 described above in step 707, the first temperature data t ₁ at step _{709 (t 0 -1 ℃) +} 0.5 ℃ (t 0 = 3.5 in the case of ° C. is (Corresponding to 3 ° C.). Accordingly, by supplying 6 V to the PTC heater 48, the temperature of the refrigerant in the evaporator inlet pipe 40 is transmitted to the thermosensitive cylinder 36, the flow rate of the refrigerant from the expansion valve 11 is reduced, and the refrigerant in the evaporator inlet pipe 40 is reduced. Try to raise the temperature. While the first temperature data t ₁ corresponding to the refrigerant temperature is lower than 3 ° C., 6 V is supplied to the PTC heater 48 by the above-described processing, and when the first temperature data t ₁ becomes a value of 3 ° C. or more, The determination in step 709 becomes YES, and the PTC energizing operation from step 702 onward is restarted.

The first temperature data t ₁ is the first temperature determination level t ₀
In the case of the above values, it is determined that the superheat degree control needs to be performed, and the determination in step 704 or 708 is YES, and the sixth
The process proceeds to the superheat degree calculation routine 600 shown in FIG.

Therefore, in the constant pressure control calculation routine 700 described above, while the first temperature data t ₁ is lower than the first temperature determination level t ₀ , the supply of 6 V and 3 V to the PTC heater 48 is repeated, The value of the refrigerant temperature is set to a value having a hysteresis of ± 0.5 ° C. centered at 2.5 ° C., and the pressure of the refrigerant flowing out of the expansion valve 11 is controlled to a substantially constant value by controlling the refrigerant temperature to a substantially constant value. Is performed.

When the economy switch 24 is turned on, the interruption process shown in FIG. Then, the process proceeds to step 802, where it is determined whether the first flag is set. By setting the first time flag in the initial setting at the start of the operation in the control circuit 21, the determination becomes YES at the first arrival to step 802, and the routine proceeds to step 803, where the first temperature determination level is set. the t ₀ is set to a value corresponding to 8 ° C., and resets the first flag proceeds to step 804, and ends the interrupt processing proceeds to step 805. By setting the first temperature determination level t ₀ to a value corresponding to 8 ° C. in this interrupt processing, when the first temperature data t ₁ is a value of 8 ° C. or more, the superheat degree calculation of FIG. performed, at the time of when the first lower temperature data t ₁ is 8 ° C. performs constant pressure control operation of FIG. 9, a hysteresis of ± 0.5 ° C. the temperature of the refrigerant flowing out from the expansion valve around a 7 ° C. Constant pressure control, that is, economy control.

When the economy switch 24 is turned on again, the determination in step 802 in the interrupt processing of FIG. 8 becomes NO, and the first temperature determination level t ₀ is set to a value corresponding to 3.5 ° C. in step 806. Then, the process proceeds to step 807 to set the first flag. Accordingly, the first temperature determination level t ₀ 3.5
The process returns to the above-described normal process in which the temperature is set to ° C.

That is, in the interruption process of FIG. 8, each time the economy switch 24 is turned on, the first temperature determination level
The economy setting in which t ₀ is 8 ° C. and the normal setting in which the first temperature determination level t ₀ is 3.5 ° C. are alternately performed.

In the present embodiment, as shown in FIG. 2, the temperature-sensitive cylinder 36 is provided in the evaporator inlet pipe 40 and provided with a heater 48, and the temperature-sensitive cylinder 36 is cooled by a refrigerant and heated by the heater 48. Although the pressure was changed and the diaphragm 34 was displaced to adjust the refrigerant flow rate, the temperature-sensitive cylinder 36 was not limited to the evaporator inlet pipe 40 as long as it was a place to be cooled. No.
As shown in FIG. 10, the thermosensitive cylinder 36 may be cooled between the evaporator 13 and the electric blower 15 by cooling it with air or a Peltier element 350. In this case, the place where the temperature-sensitive cylinder 36 is cooled may be another place such as downstream of the evaporator 13 with respect to the blowing direction of the blower by the electric blower 15. Here, when cooling with air as shown in FIG.
The temperature sensing tube 36 is heated by the plastic PTC heater 310 and cooled by air. Inside the temperature sensing cylinder 36, refrigerant having a higher boiling point than the refrigerant of the refrigeration cycle (for example, R-11, R-113, R-1)
14) are enclosed as a mixture of liquid 312 and gas 314. The inside of the capillary 35 connected to the diaphragm is entirely filled with the liquid 312. Note that fins may be provided on the surface of the temperature-sensitive cylinder 36 to promote heat transfer. Further, the cooling may be performed by a Peltier element instead of the PTC heater 310, or the broadcast of the cooling and the heating may be performed by the Peltier element by switching between + and-of the power supply to the Peltier element.

In the figures, 351 and 352 are plate-like aluminum fins for heat exchange, 354 (a) and 354 (b) are copper clips for fixing the Peltier element to the temperature sensing tube 350, 356, 358, 360, and 362 are ceramic plates, and 364, 366, 368, and 370 are copper plates. , 372, 374 are P-type semiconductors, 376, 378 are N-type semiconductors, the P-type semiconductor 372 is connected to the positive electrode, the N-type semiconductor 378 is connected to the negative electrode, and the N-type semiconductor 376 and the P-type semiconductor 374 are electrically connected by a connection line 735. It is connected. Silicon grease is applied between the temperature sensing tube 350 and the ceramic plates 358 and 360, between the aluminum fin 351 and the ceramic plate 356, and between the aluminum fin 352 and the ceramic plate 362.

In all the embodiments, the evaporator inlet refrigerant temperature,
Similar control can be performed by detecting the evaporator inlet refrigerant pressure and the temperature-sensitive cylinder pressure instead of the temperature-sensitive cylinder temperature. In this case, the semiconductor pressure sensor may be provided in the evaporator inlet pipe 40 or in the temperature-sensitive cylinder.

Also, in the control to heat and cool the temperature sensitive member, PID
Control may be performed.

In the superheat control and the constant pressure control, the control target value may be variable for more detailed control.

〔The invention's effect〕

The present invention is configured as described above, and has the following effects.

In the expansion valve control device for a refrigerator according to the first aspect, the pressure of the pressure medium sealed in the temperature-sensitive member is set higher than the pressure of the pressure medium corresponding to the electrical target heating degree of the evaporator. Pressure increasing means, and pressure decreasing means for lowering the pressure of the pressure medium sealed in the temperature sensing member to be lower than the pressure of the pressure medium corresponding to the degree of heating of the evaporator to be electrically targeted. Therefore, the target heating degree of the evaporator can be higher or lower than the heating degree of the electrically detected evaporator,
Further, it is possible to quickly approach the target heating degree of the evaporator.

In the expansion valve control device for a refrigerator according to claim 2, the pressure of the pressure medium sealed in the temperature-sensitive member is set to be higher than the pressure of the pressure medium corresponding to the physical quantity of the refrigerant at the inlet of the evaporator, which is electrically targeted. Pressure increasing means for increasing pressure, and pressure decreasing means for decreasing the pressure of the pressure medium sealed in the temperature sensing member to be lower than the pressure of the pressure medium corresponding to the physical quantity of the refrigerant at the inlet of the evaporator to be electrically targeted. Therefore, the physical quantity of the target refrigerant at the inlet of the evaporator can be higher or lower than the physical quantity of the refrigerant at the inlet of the evaporator electrically detected. The physical quantity of the refrigerant can be quickly approached.

In the expansion valve control device for a refrigerator according to claim 3, since the temperature-sensitive member is thermally connected to the inlet of the evaporator, the temperature-sensitive member can lower the temperature to the inlet of the evaporator.
The temperature of the temperature-sensitive member can be increased by heating the temperature-sensitive member.

In the refrigerating machine expansion valve control device according to the fourth aspect, since the heating device and the cooling device are provided, the temperature of the temperature-sensitive member can be more accurately changed.

In the refrigerating machine expansion valve control device according to the fifth and sixth aspects, overheating of the temperature-sensitive member is performed by the thermoelectric element, so that the control is more accurate.

In the expansion valve control device for a refrigerator according to claim 7,
Since the temperature sensing member is cooled by the flow of air, the cooling means is simplified.

In the expansion valve control device for a refrigerator, the opening and closing of the valve element is performed by applying a voltage, and the applied voltage is variable, so that the response immediately after the start of the refrigerator is improved.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing a system configuration showing an embodiment of the present invention, FIG. 2 is a diagram showing a relationship among an expansion valve, an evaporator, a temperature sensor, and a control circuit in the above embodiment, FIG. FIG. 3 (b) is a diagram showing a detailed configuration near the temperature sensing cylinder, FIGS. 3 (c) and 3 (d) are diagrams showing the shape of the heat conduction block, and FIG. 5 to 8 are flow charts showing the arithmetic processing of the control circuit shown in FIGS. 1 and 2;
9 and 10 show another embodiment of the present invention. 1 ... variable capacity compressor, 3 ... condenser, 9 ... liquid receiver, 11 ...
... Expansion valve, 13 ... Evaporator, 17,19 ... Temperature sensor, 21 ... Control circuit, 30 ... Valve, 34 ... Diaphragm, 35 ... Capillary, 36 ... Temperature sensing cylinder, 48 ... PTC heater.

Claims (8)

(57) [Claims] A diaphragm is displaced in accordance with the pressure of a pressure medium sealed in a temperature-sensitive member, and a degree of heating of an evaporator is controlled by controlling an opening degree of a valve body connected to the diaphragm. An expansion valve control device for a refrigerator for controlling a flow rate of a refrigerant flowing into an evaporator so as to match a heating degree of the evaporator, wherein a detecting means for electrically detecting a heating degree of the evaporator; Control means for making the heating degree of the evaporator electrically detected by the means equal to the target heating degree of the evaporator; and the pressure of the pressure medium sealed in the temperature-sensitive member, Pressure increasing means for electrically increasing the pressure of the pressure medium corresponding to the degree of heating of the evaporator to be heated; and heating the evaporator to the target pressure of the pressure medium sealed in the temperature-sensitive member. The pressure of the pressure medium corresponding to the An expansion valve control device for a refrigerator, comprising: pressure reducing means for electrically lowering the pressure. The diaphragm is displaced in accordance with the pressure of the pressure medium sealed in the temperature-sensitive member, and the opening degree of a valve connected to the diaphragm is controlled to correspond to the pressure of the refrigerant at the inlet of the evaporator. The expansion valve control device for a refrigerator controls the flow rate of the refrigerant flowing into the evaporator so that the physical quantity to be adjusted matches the physical quantity corresponding to the target pressure of the refrigerant at the entrance of the evaporator. Detecting means for electrically detecting a physical quantity corresponding to the pressure of the evaporator, a physical quantity corresponding to the pressure of the inlet refrigerant of the evaporator electrically detected by the detecting means, Control means for matching a physical quantity corresponding to the pressure; and a pressure of the pressure medium corresponding to a physical quantity corresponding to the target pressure of the refrigerant at the inlet of the evaporator, the pressure of the pressure medium sealed in the temperature-sensitive member. Pressure increasing means for electrically increasing the pressure, and the pressure of the pressure medium sealed in the temperature sensing member, the pressure of the pressure medium corresponding to the physical quantity corresponding to the pressure of the target refrigerant at the inlet of the evaporator. An expansion valve control device for a refrigerator, comprising: pressure reducing means for electrically lowering the pressure. 3. The temperature-sensitive member is thermally connected to an inlet of the evaporator, and the pressure increasing means increases the pressure of the pressure medium by heating the temperature-sensitive member. The expansion valve control device for a refrigerator according to claim 1 or 2, wherein the expansion valve control device is a means. 4. The pressure increasing means is a heating means for increasing the pressure of the pressure medium by heating the temperature sensitive member, and the pressure decreasing means is configured to cool the temperature sensitive member, The expansion valve control device for a refrigerator according to claim 1 or 2, wherein the cooling device is a cooling unit that reduces the pressure of the pressure medium. 5. An expansion valve control device for a refrigerator according to claim 3, wherein said heating means is a thermoelectric element. 6. An expansion valve control device for a refrigerator according to claim 4, wherein said heating means and said cooling means are thermoelectric elements. 7. The expansion valve control device for a refrigerator according to claim 4, wherein said cooling means is means for cooling by a flow of air. 8. At least one of the pressure increasing means and the pressure decreasing means is means for increasing or decreasing the pressure of a pressure medium sealed in the temperature-sensitive member by applying a voltage, and The expansion valve control device for a refrigerator according to any one of claims 1 to 6, wherein the voltage is variable.