JPH04350384A - Differential pressure type oil feeding device in refrigerating facility - Google Patents

Abstract

PURPOSE:To feed oil without shortage by differential pressure oil feeding even in the case of small pressure difference without using an oil pump. CONSTITUTION:A pressure detector 11 is provided to detect the discharge side pressure of a compressor 1. A motor-driven flow control valve 12 changed in valve opening by a pressure signal from the pressure detector 11 is provided on the exit side of an oil separator 2. The flow is regulated by the opening control of the flow control valve 12 to control the discharge side pressure to be more than the fixed pressure required for differential pressure oil feeding and thereby to enable oil feeding without shortage by differential pressure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure lubrication system for a refrigeration system, and more particularly, to a differential pressure lubrication system for lubricating a compressor using a differential pressure between the suction side and the discharge side of the compressor. .

0002

2. Description of the Related Art Conventionally, a compressor oil supply system used in a refrigeration system is disclosed in, for example, Japanese Utility Model Application No. 55-170491, and as shown in FIG. An oil supply separator B is provided on the discharge side of the machine A, and the oil separated by the oil separator B is supplied from the oil cooler C to the intermediate pressure part of the compressor A through the first oil supply pipe D. In addition, there is also known a system in which differential pressure oil is supplied to the suction side of the compressor A through a second oil supply pipe F which is interposed with a solenoid valve E that opens at startup.

0003

[Problems to be Solved by the Invention] However, when the compressor A is supplied with oil using the differential pressure between the pressure on the discharge side of the compressor A and the pressure on the discharge side of the compressor A as described above, it is difficult not only to start up the compressor but also to perform cooling operation in winter. When the pressure on the discharge side decreases, such as when the outside temperature is low or the load is small, it takes a long time to replenish the oil, or there is insufficient lubrication, and in some cases, seizure may occur due to insufficient lubrication. There was a problem.

[0004] To solve this problem, oil pumps are used,
There are also models in which the oil tank is installed higher than the compressor so that even when the differential pressure is small, there is no shortage of oil through forced lubrication or head differential lubrication, but an oil pump and oil tank are installed separately. It is necessary and costly,
Moreover, installation space is also required for installing the oil pump and oil tank, which increases the size of the entire device, which does not solve the problem of differential pressure oil supply.

[0005] An object of the present invention is to provide a differential pressure oil supply device that can supply oil by differential pressure without using an oil pump or the like, and can supply oil without running out of oil even when the outside temperature drops or the load decreases. It is in the point of doing.

[0006]

[Means for Solving the Problems] The present invention includes a compressor 1, an oil separator 2, a condenser 7, and an evaporator 9. In a differential pressure oil supply device that supplies oil separated by an oil separator 2 based on differential pressure, a pressure detector 11 is provided to detect the pressure on the discharge side of the compressor 1, and a pressure sensor 11 is provided on the outlet side of the oil separator 2. To,
A pressure control mechanism 14 is provided to control the discharge side pressure of the compressor 1 to a constant pressure or higher using a pressure signal from the pressure detector 11.

[0007] Further, it is preferable that the pressure control mechanism 14 is constituted by an electric flow rate control valve 12. Further, the pressure control mechanism 14 may include a solenoid valve 15 and a plurality of flow rate control passages 16, 17, and 18 having different flow rates.

[0008]

[Operation] When the pressure on the discharge side of the compressor 1 becomes lower than the pressure required for differential pressure oil supply due to a drop in outside air temperature or a decrease in load, this discharge side pressure is detected by the pressure detector 11 and the pressure is The control mechanism 14 is operated, and the pressure control mechanism 14 is operated so that the pressure of the oil separator 2 reaches the limit pressure (2 to 2) required for differential pressure oil supply. 3Kg/cm2)
This allows oil to be reliably supplied by differential pressure regardless of outside temperature or load reduction.

Furthermore, when the pressure control mechanism 14 is configured using the electric flow rate control valve 12, the flow rate can be controlled in accordance with the decrease in the discharge side pressure, and the pressure of the oil separator 2 can be controlled linearly. The controllability can be improved.

Further, when the pressure control mechanism 14 is configured using a plurality of flow rate control passages 16, 17, 18, a solenoid valve 15 provided in the flow rate control passages 16, 17, 18 may be opened and closed. Since the pressure in the oil separator 2 can be controlled by this, the control circuit can be simplified.

[0011]

[Embodiment] The refrigeration system shown in FIG. 1 is provided with an oil separator 2 on the discharge side of a screw compressor 1. The compressor 1
A condenser 7 is connected to the outlet side of the oil separator 2 in the gas region via a high-pressure gas pipe 6. An evaporator 9 is connected to the outlet side via an expansion valve 8, and the outlet side of the evaporator 9 is connected to the suction side of the compressor 1,
It forms a refrigeration cycle that circulates refrigerant as shown by the arrow.

[0012]The discharge gas pipe 10 connected to the discharge side of the compressor 1 is provided with a pressure detector 11 for detecting the discharge side pressure, and the pressure detector 11 connected to the discharge side of the oil separator 2 is provided The high-pressure gas pipe 6 is configured to operate in the closing direction when the discharge side pressure falls below a predetermined pressure, in other words, when the pressure falls below the pressure required for differential pressure oil supply, based on the pressure signal from the pressure detector 11. an electric flow rate control valve 12 that controls the flow rate of the high-pressure gas refrigerant flowing through the high-pressure gas pipe 6 and controls the discharge side pressure to a constant pressure, that is, a pressure higher than the pressure required for differential pressure refueling; a pressure control mechanism 1 consisting of a controller 13 that sets the opening degree of the pressure signal based on a pressure signal;
4.

That is, the flow rate control valve 12 uses a proportional control valve whose opening degree can be adjusted in proportion to the current value based on the pressure signal from the pressure detector 11.
The opening degree is set based on the pressure signal from the pressure detector 11, and the current applied to the flow control valve 12 is controlled so that the opening degree is set, and the valve opening degree is controlled in the closing direction. be. Therefore, the flow rate of the high-pressure gas refrigerant is controlled by this valve opening degree control, and the pressure in the path from the discharge side of the compressor 1 to the flow rate control valve 12, that is, the pressure in the path including the oil separator 2, is The pressure is controlled to be above the above-mentioned constant pressure required for pressure oil supply.

[0014] When the compressor 1 is driven to perform cooling operation, the compressor 1 is operated at a differential pressure ΔP between the discharge side pressure PH and the suction side pressure PL of about 10 kg/cm2 at the rated time. , the flow control valve 12 is fully opened, and the oil separated by the oil separator 2 due to the differential pressure ΔP is completely supplied to the oil supply location of the compressor 1.

In the case of performing cooling operation as described above, when the air conditioner is started, the outside temperature is low, or the load is small, the condensing pressure is low, so the differential pressure ΔP becomes small, and the differential pressure lubrication is affected. Necessary critical differential pressure (2-3Kg/cm2)
If the flow rate control valve 1 becomes smaller, differential pressure oil supply cannot be performed conventionally, but in the embodiment shown in FIG.
2 is controlled in the closing direction by the pressure signal from the pressure detector 11, and the discharge side pressure of the path including the oil separator 2 is at least a certain pressure higher than the condensing pressure, that is, at least the pressure that requires differential pressure oil supply. The differential pressure required for refueling can be ensured.

Therefore, even without using an oil pump or the like, and even if the differential pressure falls below the limit differential pressure due to a drop in outside temperature or a decrease in load, the differential pressure allows for sufficient oil supply. It is.

Furthermore, since the flow rate control valve 12 is used to control the discharge side pressure, linear pressure control can be performed and the controllability can be improved.

In the embodiment shown in FIG. 1, the flow rate control valve 12 is used as the pressure control mechanism 14, but as shown in FIG. It may also be constituted by flow rate control passages 16, 17, and 18.

In this case, based on the pressure signal from the pressure detector 11, the solenoid valve 15 of the flow rate control passage 16 at the rated flow rate is closed, and of the remaining flow rate control passages 17 and 18, the one on the side with a higher flow rate is closed. The electromagnetic valve 15 of the flow rate control passage 17 is opened, and when the above-mentioned constant pressure cannot be obtained by controlling the flow rate using the flow rate control passage 17, the electromagnetic valve 15 on the side with a large flow rate is closed to reduce the flow rate. The electromagnetic valve 15 of the flow rate control passage 18 on the low flow rate side is opened, and by selecting these flow rate control passages 16, 17, and 18, the discharge side pressure can be controlled to a level higher than the constant pressure required for differential pressure oil supply.

In addition, in FIG. 2, the flow rate control passage 16,
Although three 17, 18 are formed, it is also possible to have more than 3, and the flow rate through each flow control passage 16, 17, 18 may be set depending on the pipe diameter, but the electromagnetic valve 15 It may be set based on the opening area during the opening operation.

[0021] Also, each of the flow rate control passages 16, 17, 1
The selection control of the solenoid valve 15 provided in the pressure sensor 1
Alternatively, the pressure sensor 11 may be provided with a plurality of pressure switches, and each of the solenoid valves 15 may be connected to these pressure switches. If the flow rate control valve 12 is
The control circuit can be simplified compared to the case where the control circuit is used.

Further, the opening degree control of the flow rate control valve 12 and the electromagnetic valve 1 provided in each of the flow rate control passages 16, 17, 18 are also carried out.
The selection control of 5 is performed only by the pressure signal from the pressure detector 11, but a low-pressure pressure detector is provided on the suction side of the compressor 1 to detect the difference between the discharge side pressure and the suction side pressure. It may also be controlled by pressure.

[0023]

Effects of the Invention The present invention includes a compressor 1, an oil separator 2, a condenser 7, and an evaporator 9.
In a differential pressure oil supply device that supplies oil separated by an oil separator 2 due to a pressure difference between the suction side and the discharge side of the compressor 1, a pressure detector 11 is provided to detect the pressure on the discharge side of the compressor 1. , a pressure detector 1 is installed on the outlet side of the oil separator 2.
Since the pressure control mechanism 14 is provided to control the discharge side pressure of the compressor 1 to a certain pressure or higher using the pressure signal from the compressor 1, it can be used not only at startup but also during freezing operation in winter when the outside air temperature is low. Even when the condensing pressure is low, such as when the load is small or when the load is small, the discharge side pressure can be controlled above a certain level, that is, above the pressure required for differential pressure lubrication. Therefore, differential pressure lubrication can provide sufficient lubrication without using an oil pump etc. It is possible to do so.

[0024] Also, unlike the conventional example, there is no need to provide a special oil pump or oil tank, so costs can be reduced.
There is no need to take up a lot of installation space, and the problem of increasing the size can be avoided.

Furthermore, by using the electric flow rate control valve 12 as the pressure control mechanism 14, the discharge side pressure can be controlled linearly according to pressure changes, and the controllability can be improved. In the case of a valve 15 and a plurality of flow control passages 16, 17, 18 having different flow rates, the discharge side pressure can be controlled by opening and closing the electromagnetic valve 15, so the control circuit can be simplified.

[Brief explanation of drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration system to which an embodiment of the present invention is applied.

FIG. 2 is a refrigerant piping system diagram of a refrigeration system to which another embodiment of the present invention is applied.

FIG. 3 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

1... Compressor 2...Oil separator 7... Condenser 9...Evaporator 11...Pressure detector 12...Electric flow control valve 14...Pressure control mechanism 15... Solenoid valve 16-18...Flow rate control passage

Claims (3)

[Claims] 1. A compressor 1, an oil separator 2, a condenser 7, and an evaporator 9 are provided. In a differential pressure oil supply system that supplies oil separated by a A differential pressure oil supply device for a refrigeration system, characterized in that a pressure control mechanism 14 is provided for controlling the discharge side pressure of the compressor 1 to a constant pressure or higher using a pressure signal. [Claim 2] The pressure control mechanism 14 is an electric flow control valve 1.
2. The differential pressure oil supply device in a refrigeration system according to claim 1. 3. The pressure control mechanism 14 has a solenoid valve 15 and a plurality of flow rate control passages 16, 17, 18 having different flow rates.
A differential pressure oil supply device for a refrigeration system according to claim 1, comprising: