JPH05118717A - Refrigerant loading deficiency detector of refrigerator - Google Patents

Abstract

PURPOSE:To ensure a refrigerant loading deficiency detector device of a refrigerator for securely detecting refrigerant loading dificiency without being influenced by the state of freezing load. CONSTITUTION:There are provided high pressure pipe flow rate detector 10 for detecting the flow rate of a refrigerant flowing through a high pressure piping 8 of a freezing cycle, and comparator 40 for comparing a flow rate detected by the pressure pipe flow rate detector 10 with a preset reference and issuing a signal indicative of the loading deficiency of a refrigerant loaded in the freezing cycle when the foregoing flow rate exceeds the reference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant filling amount shortage detecting device for a refrigerating device for detecting a refrigerant filling amount shortage in a refrigerating cycle of an automobile air conditioner or the like.

[0002]

2. Description of the Related Art The amount of refrigerant charged (filled) in a refrigerating cycle has a great influence on the refrigerating capacity, so that it is necessary to keep it at an appropriate amount.

When the amount of refrigerant filled is too large, the pressure on the high-pressure side of the refrigeration cycle becomes high and the refrigeration efficiency deteriorates. However, overfilling is relatively easy by attaching a high-pressure pressure switch to the high-pressure pipe. Can be detected.

On the other hand, when the amount of refrigerant filled is too small, the refrigerating capacity is lowered and the degree of superheat on the evaporator outlet side of the low-pressure pipe is increased. Therefore, conventionally, a method of detecting underfilling by mounting a superheat switch on the evaporator outlet side of the low-pressure pipe has been studied.

[0005]

In a normal state, the degree of superheat on the outlet side of the evaporator is controlled to about 4 to 12 degrees by the expansion valve, and when the filling amount of the refrigerant becomes insufficient, the superheat at this point is overheated. When the refrigeration load is large, the degree of superheat becomes about 25 degrees. Therefore, the detection level of the superheat degree switch may be set to about 15 degrees.

However, the degree of superheat greatly varies depending on the load of the refrigerating device, and when the refrigerating load is small, the superheat does not become large even if the amount of refrigerant charged is small. Therefore, when the refrigeration load fluctuates, it becomes impossible to detect the shortage of the refrigerant filling amount.

[0007] Therefore, an object of the present invention is to provide a refrigerant shortage amount detecting device for a refrigeration system capable of surely detecting the shortage of the refrigerant filling amount without being affected by the state of the refrigeration load.

[0008]

In order to achieve the above-mentioned object, a refrigerant shortage detection device for a refrigeration system of the present invention is a high-pressure pipe flow rate for detecting the flow rate of a refrigerant flowing in a high-pressure pipe of a refrigeration cycle. The detection means and the flow rate value detected by the high-pressure pipe flow rate detection means are compared with a preset reference value, and when the flow rate value exceeds the reference value, the refrigerant filled in the refrigeration cycle. Is provided, and a comparison means for outputting a signal indicating that the filling amount is insufficient.

Note that an operation inhibiting means immediately after activation may be provided to prevent the signal from being output from the comparison means for a predetermined time after the refrigeration cycle is activated.
Further, the reference value may change in association with a change in the rotation speed of the compressor.

[0010]

Although a liquid state refrigerant (refrigerant liquid) normally flows in the high-pressure pipe, when the filling amount of the refrigerant becomes too small, the amount of vapor contained in the flowing refrigerant liquid increases. Then, as the amount of steam increases, the flow rate value detected by the high-pressure pipe flow rate detection means becomes extremely larger than the actual mass flow rate, and when the detected flow rate value exceeds the reference value, the refrigerant charge amount A signal indicating the shortage is output from the comparison means.

[0011]

Embodiments will be described with reference to the drawings. FIG. 1 shows a refrigeration cycle used in a vehicle air conditioner or the like, in which a refrigerant compressed to a high pressure by a compressor 1 releases heat in a condenser 2 and is liquefied to be in a liquid state (refrigerant liquid). )
Are temporarily stored in the liquid receiver 3. Reference numeral 3a is a sight glass made of transparent glass for observing the inside of the liquid receiver 3 from the outside in order to confirm the generation state of vapor bubbles in the refrigerant liquid.

The refrigerant liquid discharged from the liquid receiver 3 is adiabatically expanded by the expansion valve 4 and enters the evaporator 5, where it absorbs heat and is vaporized and returned to the compressor 1. Reference numeral 6 is a temperature sensitive tube for controlling the operation of the expansion valve 4. A pressure switch 7 is attached to the liquid receiver 3 to detect the pressure of the refrigerant.

A flow rate detector 10 for detecting the flow rate of the refrigerant liquid flowing inside is attached to the high pressure pipe 8 between the condenser 2 and the expansion valve 4. The flow rate detector 10
May be attached upstream of the liquid receiver 3 as shown by the solid line in FIG. 1, or may be attached downstream of the liquid receiver 3 as shown by the broken line, or You may attach to 3.

The output signal from the flow rate detector 10, that is, the detected flow rate value is input to the comparator 40 where it is compared with a preset reference value. The comparator 40 outputs a signal when the detected flow rate value is larger than the reference value.

Then, the output signal from the comparator 40 is input to the drive circuit 42 of the alarm 41 displayed by a lamp, and the alarm 41 is turned on. However, the alarm may sound and a safety device for stopping the refrigeration cycle may be provided.

A timer 43 is connected to the driving power source of the comparator 40. The timer 43 is provided for the comparator 40 when the refrigeration cycle is continuously operated for a predetermined time (for example, 5 minutes).
When the refrigeration cycle is stopped by turning on the power of the comparator 40
Power off. Therefore, the alarm 41 is not turned on for a certain time (for example, 5 minutes) after the activation of the refrigeration cycle, regardless of the state of the output signal of the flow rate detector 10.

Since the purpose of the timer 43 is to prevent the alarm 41 from operating for a certain time after the start of the refrigeration cycle, the operation of the flow rate detector 10 or the alarm 41 may be limited to a certain time. , Also, during that fixed time
For example, the reference value may be changed to a very large value.

FIG. 2 shows an example of the flow rate detector 10. A flapper 11 having one end rotatably supported in the high-pressure pipe 8 blocks the high-pressure pipe 8 against the flow of the refrigerant liquid. A spring 12 is biased in the direction.

A permanent magnet 13 is fixed to the flapper 11, and a magnetic sensor 14 for detecting the magnetic force generated by the permanent magnet 13 and converting it into an electric signal is attached to the outer surface of the high-pressure pipe 8.

Therefore, when the flow rate of the refrigerant liquid in the high-pressure pipe 8 changes, the flapper 11 rotates following the change,
The flow rate of the refrigerant liquid is detected by changing the strength of the magnetic field from the permanent magnet 13 exerted on the magnetic sensor 14 and changing the output of the magnetic sensor 14.

However, the flow rate detector 10 is not intended to detect the flow rate of the refrigerant liquid itself. That is, if the amount of the refrigerant filled becomes too small and vapor bubbles are mixed in the refrigerant liquid,
The flapper 11 is strongly pressed by the flapper 11 and is largely rotated in the opening direction, and the output from the magnetic sensor 14 is increased due to the approach of the permanent magnet 13, whereby the mixing of vapor bubbles, that is, the insufficient filling amount of the refrigerant is detected. To be done.

FIG. 3 shows a second example of the flow rate detector 10, in which a float 22 biased by a compression coil spring 21 in a direction against the flow of the refrigerant liquid is axially arranged in the high pressure pipe 8. Is arranged so as to be movable, and the distance between the permanent magnet 23 fixed to one end of the float 22 and the magnetic sensor 24 is changed by the change in the flow rate of the refrigerant liquid.

Therefore, also in this case, when the amount of the refrigerant filled becomes too small and vapor bubbles are mixed with the refrigerant liquid, the output from the magnetic sensor 24 increases. FIG. 4 shows a third example of the flow rate detector 10, in which an electric contact (moving contact) 32 is attached to the tip of a flapper 31 made of a conductive leaf spring.
A switch is provided so that when the movable contact 32 comes into contact with the fixed contact 33 when the flapper 31 is largely pushed by the flow in the high-pressure pipe 8, a signal flows through the signal line 34. Reference numeral 35 is an electric insulating material.

As described above, the flow rate detector 10 has only to detect whether or not the reference flow rate value has been reached,
It is not always necessary that the change in the flow rate can be continuously detected. In this case, when the refrigerant filling amount becomes too small and vapor bubbles are mixed in the refrigerant liquid, the switch is turned on and a signal flows through the signal line 34.

FIG. 5 shows a fourth embodiment of the flow rate detector 10, in which a spiral impeller 37 has a shaft 37a between a pair of straight flow straightening vanes 36 arranged in series in the flow of the refrigerant. Is provided so as to be rotatable about the center of the impeller 37, and the rotational movement of the permanent magnet 38 attached to the outer end of the impeller 37 is detected by a magnetic sensing means 39 such as a Hall element.

With such a configuration, one pulse signal is generated by the magnetic sensing means 39 each time the permanent magnet 38 rotates and the magnetic field of the permanent magnet 38 enters the sensing range of the magnetic sensing means 39.
And the output pulse signal is sent to an external circuit (not shown).

Since the rotation speed of the permanent magnet 38 is proportional to the flow rate of the refrigerant, the flow rate of the refrigerant can be continuously and accurately detected by counting the frequency of this pulse signal.

The flow rate detector 10 is not limited to the above-mentioned embodiments, and any kind of flow rate detector may be provided. If cost permits, a capacity flow meter such as an oval flow meter can be used. ..

FIG. 6 shows an example of the relationship between the refrigerant charge amount and the flow rate value detected by the flow rate detector 10 when the float type shown in FIG. 3 is used as the flow rate detector 10. The solid line shows the case where the flow rate detector 10 is attached upstream of the liquid receiver 3, and the broken line shows the flow rate detector 10 as the liquid receiver 3.
The case where it is attached further downstream is shown. However, the number of rotations of the compressor 1 is 800.

In this case, the refrigerant charge amount is 1000
When it goes below g, vapor bubbles start to be generated. Therefore, in order to turn on the alarm 41 when the filling amount of the refrigerant falls below 800 g, when the flow rate detector 10 is installed upstream of the liquid receiver 3, the reference value is set to about 220 [liter / It is understood that the reference value may be set to about 135 [liter / hour] when the flow rate detector 10 is attached downstream of the liquid receiver 3.

However, the reference value may be changed in association with the rotation speed of the compressor 1. In that case, as illustrated in FIG. 7, a rotation speed sensor 4 for detecting the rotation speed of the compressor 1 is provided in a reference value setting circuit 45 for setting a reference value.
The reference value may be changed by inputting the output signal from No. 6, and when the output voltage from the rotation speed sensor 46 can be directly used as the reference value, the reference value setting circuit 45 is omitted. can do. Further, in the case of an automobile, the compressor 1 is rotationally driven by the engine,
You may make it detect the rotation speed of an engine.

When the reference value is set to a fixed value, the value is set in consideration of the case where the compressor 1 is rotating at a high speed. For example, in the case of the solid line in FIG. 6, it is about 300 [liter / hour]. Set.

FIG. 8 shows the results of an experiment in which the output of the flow rate detector 10 after starting was measured by changing the number of revolutions of the compressor 1 to three types. As described above, it takes 2-3 minutes until a stable output is obtained from the flow rate detector 10, and during that time, the output value from the flow rate detector 10 becomes larger than the reference value, and the alarm 41 may be activated. is there. So timer 4
The set of 3 was 5 minutes as described above.

[0034]

According to the refrigerant shortage amount detecting device for the refrigeration system of the present invention, since the refrigerant shortage amount is detected from the detected flow rate value of the flow rate detecting means provided in the high-pressure pipe, Insufficient amount of refrigerant can be reliably detected without being affected by the state.

If the detection operation of the insufficient filling amount is not performed for a predetermined time after the refrigeration cycle is activated, the malfunction can be prevented by avoiding the unstable detection state. If the value is linked to the rotation speed of the compressor, it is possible to always accurately detect the shortage of the filling quantity of the refrigerant in accordance with the limit level of the shortage amount of the refrigerant that changes depending on the rotation speed of the compressor.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a refrigeration cycle according to an embodiment.

FIG. 2 is a sectional view of a first example of a flow rate detector.

FIG. 3 is a sectional view of a second example of the flow rate detector.

FIG. 4 is a sectional view of a third example of the flow rate detector.

FIG. 5 is a sectional view of a fourth example of the flow rate detector.

FIG. 6 is a diagram illustrating a relationship between a refrigerant charge amount and a detected flow rate.

FIG. 7 is a partial block diagram of a circuit when the reference value is variable.

FIG. 8 is a diagram illustrating a change over time in the detected flow rate.

[Explanation of symbols]

 8 High-pressure piping 10 Flow rate detector 40 Comparator

Claims (3)

[Claims] 1. A high-pressure pipe flow rate detecting means for detecting a flow rate of a refrigerant flowing through a high-pressure pipe of a refrigeration cycle, and comparing the flow rate value detected by the high-pressure pipe flow rate detecting means with a preset reference value. The refrigerating apparatus is further provided with a comparison unit that outputs a signal indicating that the amount of the refrigerant filled in the refrigeration cycle is insufficient when the flow rate value exceeds the reference value. Insufficient refrigerant filling amount detection device. 2. The refrigerating apparatus according to claim 1, further comprising an operation inhibiting means immediately after activation for preventing the signal from being output from the comparing means for a predetermined time after the refrigeration cycle is activated. Refrigerant charge shortage detection device. 3. The refrigerant charge shortage detection device for a refrigeration system according to claim 1, wherein the reference value changes in association with a change in the rotation speed of the compressor.