JPH08200860A - Refrigerator - Google Patents

Abstract

PURPOSE: To protect a refrigerant compressor by preventing the retention of oil in a refrigerator in which a solenoid valve is provided at the downstream of a refrigerant evaporator. CONSTITUTION: In a refrigerating cycle 1 in which a front side evaporator 7a, a rear side evaporator 7c and an evaporator 7b for a refrigerator are connected in parallel, solenoid valves 9, 10 are provided at the upstream of the evaporator 7a and the downstream of the evaporator 7c. A controller 2 for controlling the operating state of the cycle 1 decides whether leakage occurs at the valve 10 according to the differential pressure between the front and rear side of the valve 10 when an AC switch is not closed corresponding to the evaporator 7c. If the leakage is decided, whether the oil is retained by the downstream side pressure of the valve 10 is decided. When the retention of the coil is decided, a solenoid valve for opening the valve 10 is controlled for a predetermined time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system in which a plurality of refrigerant evaporators are connected in parallel and an electromagnetic valve is provided downstream of at least one refrigerant evaporator.

[0002]

2. Description of the Related Art Conventionally, there is a refrigerating apparatus having a plurality of refrigerant evaporators. For example, in a vehicle equipped with a refrigerator, as shown in FIG. 6, a front-side refrigerant evaporator 100 and a rear-side refrigerant evaporator 110 that cool the inside of the vehicle compartment, and a refrigerant evaporator 120 for a refrigerator are provided, and one refrigerant is provided. Compressor 130
Are connected in parallel to.

This refrigeration system is equipped with a refrigerant evaporator 1 for a refrigerator.
20 is provided with a pressure-operated expansion valve 140 for lowering the evaporation pressure of the refrigerant, and each electromagnetic valve provided upstream of the front-side refrigerant evaporator 100 and downstream of the rear-side refrigerant evaporator 110. With the valves 150 and 160 closed, the expansion valve 14 is activated when the low pressure decreases to a certain value.
The refrigerant is configured to flow to zero. Therefore, in order to reduce the low pressure in a short time after closing the solenoid valves 150 and 160, the solenoid valve 160 is provided on the downstream side of the refrigerant evaporator 110 on the rear side, which is less frequently used than the front side. ing.

[0004]

In the refrigeration system described above, the low-pressure side solenoid valve 160 has a relief valve built therein.
Even if the low-pressure side solenoid valve 160 is closed, when the upstream side pressure rises and the pressure difference before and after the low-pressure side solenoid valve 160 increases, a small amount of refrigerant flows to the relief valve to suppress the rise in the upstream side pressure. Occurs. Therefore, for example, when the refrigerator is operated independently for a long time, the oil contained in the refrigerant may stay in the branch pipe 170 downstream of the low pressure side solenoid valve 160 due to the minute refrigerant flow through the relief valve. There is a nature. As a result, the amount of oil returned to the refrigerant compressor 130 decreases, which causes a problem that the smooth operation of the refrigerant compressor 130 is adversely affected. The present invention has been made based on the above circumstances, and an object of the present invention is to protect a refrigerant compressor by preventing oil from staying in a refrigeration apparatus in which a solenoid valve is provided downstream of a refrigerant evaporator. It is in.

[0005]

The present invention has the following features to attain the object mentioned above. In claim 1,
In a refrigeration apparatus in which a plurality of refrigerant evaporators are connected in parallel to one refrigerant compressor and an electromagnetic valve is provided downstream of at least one refrigerant evaporator, a start signal for starting the refrigeration apparatus is provided. Starting signal detecting means for detecting, and after the starting signal is detected by the starting signal detecting means,
A solenoid valve determining means for determining whether the solenoid valve is in a closed state, and a differential pressure before and after the solenoid valve when the solenoid valve determining means determines that the solenoid valve is in the closed state. Is within a predetermined numerical range, a differential pressure determining means for determining whether or not the differential pressure is within the predetermined numerical range by the differential pressure determining means. Side low pressure determination means for determining whether the pressure on the side is lower than a predetermined value, and when the low pressure determination means determines that the downstream pressure is lower than the predetermined value, the solenoid valve is opened for a predetermined time. And a solenoid valve opening means.

According to a second aspect of the present invention, in the refrigeration system of the first aspect, the solenoid valve has a built-in relief valve that opens when the differential pressure across the solenoid valve when the valve is closed is equal to or greater than a predetermined value. It is characterized by being

According to a third aspect of the present invention, in the refrigerating apparatus according to the first or second aspect, any one of the refrigerant evaporators is provided upstream of any one of the refrigerant evaporators other than the refrigerant evaporator having the electromagnetic valve provided downstream thereof. It is characterized in that a pressure-operated expansion valve for making the evaporation pressure substantially constant is provided.

[0008]

In the refrigerating apparatus of the present invention having the above structure, when the electromagnetic valve provided downstream of the refrigerant evaporator is closed (the refrigerating apparatus is activated), the differential pressure across the electromagnetic valve ( It is determined whether (upstream pressure−downstream pressure) is within a predetermined numerical range. If the differential pressure is within a predetermined numerical range, it is determined that the solenoid valve is leaking. Then, when it is determined that the differential pressure before and after the solenoid valve is within a predetermined numerical range, it is further determined whether the pressure on the downstream side of the solenoid valve is smaller than a predetermined value, and the downstream pressure is the predetermined value. If it is smaller, it is determined that the oil is retained downstream of the solenoid valve.
Therefore, when it is determined that the oil is accumulated in the downstream of the solenoid valve, the solenoid valve is opened for a predetermined time and the refrigerant is allowed to flow, so that the accumulated oil can be returned to the refrigerant compressor together with the refrigerant. it can.

[0009]

As a result of the above operation, oil can be prevented from staying and returned to the refrigerant compressor, so that the refrigerant compressor can be prevented from being adversely affected by insufficient oil and smooth operation of the refrigerant compressor can be performed. Be done. Further, in the present invention, the solenoid valve is opened only when it is determined that the oil is accumulated.
That is, when there is no leakage in the solenoid valve (when the differential pressure before and after the solenoid valve is outside the specified numerical range), and when it is determined that oil does not stay even if there is leakage in the solenoid valve The solenoid valve is not opened (when the downstream pressure is equal to or higher than a predetermined value). Therefore, the opening / closing operation of the solenoid valve is not performed unnecessarily, unnecessary refrigerant flowing noise can be reduced, and it is also advantageous in terms of power consumption of the engine.

[0010]

Embodiments of the refrigerating apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a refrigeration cycle.
The refrigerating apparatus of this embodiment is applied to a vehicle including a refrigerator, and a refrigerating cycle 1 of a multi-evaporator system for cooling the inside of a vehicle and cooling the inside of the refrigerator, and a control for controlling an operating state of the refrigerating cycle 1. And device 2.

The refrigeration cycle 1 comprises a refrigerant compressor 3, a refrigerant condenser 4, a receiver 5, an expansion valve 6 (6a, 6b, 6c),
And the refrigerant evaporator 7 (7a, 7b, 7c), and the refrigerant pipe 8 (branch pipes 8a, 8b, 8c).
Are included). However, the expansion valve 6 and the refrigerant evaporator 7 are separately provided for the front side cooling, the rear side cooling, and the refrigerator in the vehicle compartment.
As shown in FIG. 3, the branch pipes 8 a, 8 b, and 8 c are connected in parallel between the receiver 5 and the refrigerant compressor 3.

Further, the front side branch pipe 8a is provided with a solenoid valve 9 for opening and closing the branch pipe 8a upstream of the front side expansion valve 6a.
The rear side branch pipe 8c is provided with a rear side evaporator 7c.
An electromagnetic valve 10 that opens and closes the branch pipe 8c is provided downstream of c, and a check valve 11 that prevents the reverse flow of the refrigerant is provided downstream of the refrigerator evaporator 7b in the refrigerator branch pipe 8b.

The refrigerant compressor 3 is driven by an engine (not shown) of the vehicle via the electromagnetic clutch 12 and compresses the sucked gas refrigerant to a high temperature and a high pressure and discharges it. The refrigerant condenser 4 condenses and liquefies the high-temperature, high-pressure refrigerant discharged from the refrigerant compressor 3 by receiving air from the cooling fan 13. The receiver 5 stores the refrigerant liquefied in the refrigerant condenser 4 and flows out the liquid refrigerant.

The expansion valve 6 decompresses and expands the refrigerant sent from the receiver 5 and supplies it to the refrigerant evaporator 7. The expansion valve 6 corresponds to the front side evaporator 7a and the rear side evaporator 7c.
a and 6c are temperature-operated types that adjust the flow rate of the refrigerant so that the degree of superheat of the refrigerant flowing out from the refrigerant evaporators 7a and 7c is constant, and the expansion valve 6b corresponding to the refrigerator evaporator 7b is Is a pressure actuation type that regulates the refrigerant flow rate so that the evaporation pressure of is constant.

As described above, the refrigerant evaporator 7 is arranged in the front and rear sides of the vehicle compartment and in the refrigerator,
The refrigerant decompressed by the expansion valve 6 removes latent heat from the surrounding air and evaporates to cool the vehicle interior and cool the refrigerator.

The solenoid valves 9 and 10 are energized and controlled by the controller 2, and open when energized to open the branch pipes 8a and 8c, and close when energized to shut off the branch pipes 8a and 8c. In addition, the relief valve 10a shown in FIG. 2 is built in the rear solenoid valve 10 disposed downstream of the rear evaporator 7c. The relief valve 10a is provided to prevent the upstream side pressure of the rear solenoid valve 10 from rising when the rear solenoid valve 10 is closed. Upstream pressure P1-Downstream pressure P
2) has the flow rate characteristics shown in Fig. 3.

The control device 2 has a microcomputer (not shown) built therein, and as shown in FIG. 4, an operation signal on the operation panel 14 and pressure sensors 15 and 16 provided on the rear side branch pipe 8c. Detection value (P1, P2)
Based on, the operation control of the air conditioner is performed. The pressure sensor 15 is provided on the upstream side of the rear solenoid valve 10,
The pressure sensor 16 is provided downstream of the rear solenoid valve 10.

An A / C switch 17 for outputting a start signal for starting the refrigeration cycle 1 is provided on the operation panel 14.
(17a, 17b, 17c) are provided. This A
The / C switch 17 is provided corresponding to each refrigerant evaporator 7a, 7b, 7c. That is, the front side evaporator 7a
A / C switch 17 set to activate
a, an A / C switch 17b set to operate the refrigerator evaporator 7b, and an A / C switch 17c set to operate the rear side evaporator 7c.

The refrigeration cycle 1 is built in the rear solenoid valve 10 when, for example, the refrigerator is operated independently for a long time (therefore, the front solenoid valve 9 and the rear solenoid valve 10 are closed). Since a small amount of refrigerant flows in the relief valve 10a, the lubricating oil of the refrigerant compressor 3 contained in the refrigerant may stay in the branch pipe 8c downstream of the rear solenoid valve 10. Therefore, in the present embodiment, when the refrigeration cycle 1 is started with the rear solenoid valve 10 closed (that is, when the rear evaporator 7c is not used) (for example, the refrigerator operates independently, or the front evaporator 7a). Solenoid valve control for preventing oil retention is executed in the cooling operation using only the air conditioner.

The solenoid valve control will be described below. FIG. 5 is a flow chart showing a processing procedure of solenoid valve control. First, when a start signal for starting the refrigeration cycle 1 is input to the control device 2 (step 100, start signal detecting means of the present invention), the timer built in the control device 2 is reset (t = 0). (Step 110).

Subsequently, it is determined whether or not the rear solenoid valve 10 is closed (OFF) (step 120, solenoid valve determining means of the present invention). Specifically, according to the input start signal, the A / C switch 1 corresponding to the rear evaporator 7c
If 7c is on, it can be determined that the rear solenoid valve 10 is in the open state (on), and if the A / C switch 17c is off, the rear solenoid valve 10 is in the closed state (off). . In this determination, if the rear solenoid valve 10 is open, that is, if the A / C switch 17c is turned on, the process returns to step 110.

When the determination in step 120 is YES, that is, when the rear solenoid valve 10 is closed, the differential pressure ΔP between the upstream side pressure P1 and the downstream side pressure P2 of the rear side solenoid valve 10 is determined.
It is determined whether or not (P1 -P2) is within a predetermined numerical range (a <ΔP <b) (step 130, differential pressure determination means of the present invention). In this determination, if the differential pressure ΔP is outside the predetermined range, the process returns to step 110.

The determination in step 130 is to determine whether or not the rear solenoid valve 10 is leaking. The numerical value a indicates that the rear solenoid valve 10 is open, that is, the refrigerant flows. Is the differential pressure ΔP during the operation, for example, a = 0. The numerical value b is the differential pressure ΔP when the rear solenoid valve 10 is not leaking, and is, for example, b = 3 kg / cm ² . Therefore, even if the rear solenoid valve 10 is closed, when the rear solenoid valve 10 is leaking (that is, when the refrigerant is flowing through the relief valve 10a), the differential pressure ΔP is larger than the numeric value a and is equal to the numeric value b. It gets smaller. That is, a <ΔP
<B.

Therefore, when the determination in step 130 is YES, that is, when it is determined that the rear solenoid valve 10 is leaking, the downstream pressure P2 of the rear solenoid valve 10 is a predetermined value c (for example, c). = 0) or less (step 140, low-voltage determination means of the present invention). In this determination, if the downstream pressure P2 is larger than the predetermined value c, step 110
Return to.

The determination in step 140 is to determine whether or not oil is retained in the rear side branch pipe 8c when the rear side solenoid valve 10 is leaking, and the predetermined value c
Is a pressure when oil is not accumulated in the rear side branch pipe 8c and is sucked by the refrigerant compressor 3 together with the refrigerant even if the rear side solenoid valve 10 is leaking, for example, when c = 0. is there. Therefore, when oil is accumulated in the rear side branch pipe 8c, the downstream side pressure P2 becomes smaller than the predetermined value c due to the suction of the refrigerant compressor 3. That is, P2 <c.

Therefore, when the determination in step 140 is YES, that is, when it is determined that the oil is accumulated in the rear side branch pipe 8c, the rear side solenoid valve 10 is in the off state, but the rear side solenoid valve 10 is in the off state. The side solenoid valve 10 is energized (step 150, solenoid valve opening means of the present invention).

After energizing the rear solenoid valve 10, the controller 2
Start the counting of the timer built in (step 1
60), when the count time t of the timer reaches a predetermined time t1 (for example, 15 to 20 seconds) (when the determination in step 180 is YES), the energization of the rear solenoid valve 10 is stopped (step 190). . However, after the timer starts counting at step 160, the A / C switch 17 is operated before the count time t of the timer reaches the predetermined time t1.
If c is turned on (NO at step 170), the process returns to step 110.

After the energization of the rear solenoid valve 10 is stopped in step 190, the refrigeration cycle 1 is operated for a certain time t2 (however, t1 without turning on the A / C switch 17c).
When <t2, for example, t2: several hours) is continuously performed (YES in the determination in step 210), the process returns to step 110. However, in step 190, the rear solenoid valve 1
If the A / C switch 17c is turned on by the time the operation of the refrigeration cycle 1 elapses for a certain time t2 after the power supply to 0 is stopped (if the determination in step 200 is NO), the process returns to step 110.

By adding the process of step 210, steps 110 to 1 are performed when the refrigeration cycle 1 is started.
After performing the solenoid valve control up to 90, the next solenoid valve control is not performed until the operation of the refrigeration cycle 1 is continuously performed for the constant time t2. As a result, it is possible to prevent frequent opening / closing operations of the rear solenoid valve 10.

(Effects of the Embodiment) As described above, in this embodiment, when the refrigeration cycle 1 is started with the rear solenoid valve 10 closed, the solenoid valve control described above is performed, whereby the rear solenoid valve is operated. It is possible to prevent oil from accumulating in the rear side branch pipe 8c downstream of the valve 10. That is, when the oil stays, the rear solenoid valve 1 is operated for a predetermined time t1.
By opening 0 and flowing the refrigerant through the rear side branch pipe 8c, the retained oil can be returned to the refrigerant compressor 3 together with the refrigerant. As a result, seizure of the refrigerant compressor 3 due to lack of oil is prevented, and smooth operation can be performed.

Further, in this embodiment, the rear solenoid valve 10 is not opened and closed unnecessarily, and the rear solenoid valve 10 is opened to flow the refrigerant only when it is judged that the oil is accumulated. Have control. That is, when there is no leakage in the rear solenoid valve 10 (a ≧ ΔP or b ≦ ΔP), or when there is leakage but no oil is retained (P
In the case of 1 ≧ c), since the rear solenoid valve 10 is not opened, unnecessary refrigerant flowing noise can be reduced and deterioration of engine power consumption can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a refrigeration cycle.

FIG. 2 is a cross-sectional view showing an internal structure of a rear solenoid valve.

FIG. 3 is a graph showing a flow rate characteristic of a relief valve built in a rear solenoid valve.

FIG. 4 is a block diagram of a control system according to this embodiment.

FIG. 5 is a flowchart showing the operation of this embodiment.

FIG. 6 is a schematic diagram of a refrigeration cycle for explaining a conventional technique.

[Explanation of symbols]

2 control device (starting signal detection means, solenoid valve determination means,
Differential pressure determination means, low pressure determination means, solenoid valve opening means) 3 Refrigerant compressor 6b Expansion valve (pressure operated expansion valve) 7a Front side evaporator (refrigerant evaporator) 7b Refrigerator evaporator (refrigerant evaporator) 7c Rear side evaporator (refrigerant evaporator) 10 Rear side solenoid valve 10a Relief valve

Claims (3)

[Claims] 1. A refrigeration apparatus in which a plurality of refrigerant evaporators are connected in parallel to one refrigerant compressor, and an electromagnetic valve is provided downstream of at least one of the refrigerant evaporators: a) This refrigeration Start signal detecting means for detecting a start signal for starting the device; and b) solenoid valve determination for determining whether or not the solenoid valve is in a closed state after the start signal is detected by the start signal detecting means. And c) a differential pressure for determining whether or not the differential pressure before and after the electromagnetic valve is within a predetermined numerical range when the electromagnetic valve determination means determines that the electromagnetic valve is in a closed state. Determining means, and d) if the differential pressure determining means determines that the differential pressure is within the predetermined numerical range, it is determined whether the pressure downstream of the solenoid valve is smaller than a predetermined value. Low pressure determining means, and e) the low pressure determining means If it is determined that the side pressure is smaller than the predetermined value, the refrigeration apparatus having an electromagnetic valve opening means for a predetermined time opening the solenoid valve. 2. The refrigeration apparatus according to claim 1, wherein the solenoid valve has a built-in relief valve that opens when a differential pressure across the solenoid valve when the valve is closed is a predetermined value or more. Characterizing refrigeration equipment. 3. The refrigerating apparatus according to claim 1 or 2, other than the refrigerant evaporator in which the electromagnetic valve is provided downstream,
A refrigerating apparatus comprising a pressure-operated expansion valve that is provided upstream of any one of the refrigerant evaporators to keep the evaporation pressure of the refrigerant substantially constant.