JPH0821665A - Method and device for controlling discharge gas temperature of scroll compressor of refrigerating device - Google Patents

Abstract

PURPOSE:To maintain the optimum temperature of the inside of a compressor even when the operating condition thereof is changed suddenly. CONSTITUTION:A small-capacity capillary 7 and a big-capacity capillary 8 constitute flow passages for the liquid injection of a part of high-pressure liquid refrigerant for an intermediate pressure chamber on the way of compression in a scroll compressor 1. The opening and closing of solenoid valves 5, 6 for liquid injection, which regulate the amount of liquid injection, are controlled based on the detecting results of a pressure detector, detecting the suction pressure of the scroll compressor 1, or a temperature detector, detecting the surface temperature of the scroll compressor 1, and the like. According to this method, compressor driving electric power, which becomes reactive upon the initial period of starting of the compressor, can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system for controlling a discharge gas temperature of a scroll compressor by injecting a part of a liquid refrigerant into an intermediate pressure chamber of the scroll compressor (hereinafter, simply referred to as "injection"). In particular, the present invention relates to a discharge gas temperature control method and device for a scroll compressor of a refrigeration system, which is suitable for reliable operation in the initial stage of starting the compressor.

[0002]

2. Description of the Related Art As a method or apparatus for controlling a discharge gas temperature of such a scroll compressor of a refrigerating apparatus, for example, as disclosed in Japanese Patent Publication No. 1-269866,
Detects the discharge gas temperature and opens the injection circuit when the discharge gas temperature reaches a specified temperature, or controls the opening of the injection flow rate adjustment valve so that the discharge gas temperature reaches a specified temperature. There was something to do.

[0003]

However, the above-mentioned conventional method for controlling the discharge gas temperature of the scroll compressor of the refrigerating apparatus is a method of detecting the discharge gas temperature and controlling the injection flow rate according to the result, so that the injection flow rate can be continuously measured. Although there is no problem during operation, in a transient state such as when the compressor starts up, due to the delay in the temperature change of the discharge gas temperature detection part due to the temperature change inside the compressor and the time constant of the temperature detector, There is a problem in that the temperature inside the compressor and the temperature detected by the discharge gas temperature detector differ from each other, and the temperature inside the compressor cannot be controlled to a prescribed temperature.

As a solution to this problem, there is also an example in which a fixed amount of injection is performed at the same time as the compressor is started to reduce the delay in controlling the injection flow rate with respect to the temperature change. However, in this conventional example, there may be a case where more refrigerant than necessary is poured depending on the conditions, and in this case, the inside of the compressor becomes too cold, and the viscosity of the lubricating oil in the compressor drive mechanism decreases, etc. However, there is a problem that the compressor driving power is consumed.

Therefore, the present invention provides a discharge gas temperature control method and device for a scroll compressor of a refrigeration system capable of controlling the inside of the compressor within a constant temperature range even in a transient state where the operating state changes suddenly. To aim.

[0006]

A method for controlling a discharge gas temperature of a scroll compressor of a refrigerating apparatus according to the present invention is characterized by injecting a part of a liquid refrigerant into an intermediate pressure chamber of a scroll compressor for compressing a refrigerant. In a method for controlling a discharge gas temperature of a scroll compressor of a refrigeration apparatus for controlling a discharge gas temperature of a scroll compressor, at least one of a suction pressure at the time of starting the scroll compressor, a surface temperature of the compressor, and an ambient temperature. According to one of them, the flow rate of the refrigerant to be injected at the initial stage of starting the scroll compressor is controlled.

Further, when the suction pressure at the time of starting the scroll compressor is higher than a predetermined pressure, it is preferable that the flow rate of the refrigerant to be injected at the start of the start of the scroll compressor is a predetermined value or more.

Further, when the ambient temperature at the time of starting the scroll compressor is higher than a predetermined temperature, it is preferable that the flow rate of the refrigerant to be injected at the initial start of the scroll compressor is a predetermined value or more.

Further, when the surface temperature of the scroll compressor at startup is higher than the ambient temperature by a predetermined value or more, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is more than the predetermined value. It is preferable that

Further, when the suction pressure at startup of the scroll compressor is higher than a predetermined pressure, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is the first flow rate which is a predetermined flow rate, and When the suction pressure is lower than a predetermined pressure and the ambient temperature at the time of starting the scroll compressor is higher than a predetermined temperature, the flow rate of the refrigerant to be injected at the initial start of the scroll compressor is set to the first flow rate. Second, which is smaller than the flow rate
Flow rate, while the suction pressure is lower than a predetermined pressure, the ambient temperature is lower than a predetermined temperature, and the difference between the ambient temperature and the surface temperature at the time of starting the scroll compressor is predetermined. When the value is less than or equal to the value, it is preferable that the flow rate of the refrigerant injected at the initial startup of the scroll compressor is the third flow rate, which is a flow rate smaller than the second flow rate.

Further, instead of the above means, the flow rate of the refrigerant to be injected at the initial stage of starting the scroll compressor is determined according to the degree of superheat of the discharge gas determined by the discharge pressure and the discharge gas temperature at the time of starting the scroll compressor. It may be controlled.

Further, the discharge gas temperature control device for the scroll compressor of the refrigerating apparatus of the present invention is configured such that a part of the liquid refrigerant is injected into the intermediate pressure chamber of the scroll compressor for compressing the refrigerant, so that the scroll compressor In a discharge gas temperature control device for a scroll compressor of a refrigeration system for controlling a discharge gas temperature, a pressure detector for detecting a suction pressure of the scroll compressor and a first temperature detector for detecting a surface temperature of the scroll compressor. A second temperature detector for detecting the ambient temperature of the scroll compressor, and a flow rate adjusting means for adjusting the flow rate of the injected refrigerant.
And a control means for controlling the flow rate adjusting means based on the detection results of the pressure detector, the first temperature detector, and the second temperature detector, and the control means of the scroll compressor. When the suction pressure at startup is higher than a predetermined pressure, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is the first flow rate that is a predetermined flow rate, while the suction pressure is higher than the predetermined pressure. When the scroll compressor is low and the ambient temperature at the time of starting the scroll compressor is higher than a predetermined temperature, the flow rate of the refrigerant injected at the initial start-up of the scroll compressor is a flow rate smaller than the first flow rate. Flow rate, while the suction pressure is lower than a predetermined pressure, the ambient temperature is lower than a predetermined temperature, and the ambient temperature and the start-up time of the scroll compressor are When the difference from the surface temperature is equal to or less than a predetermined value, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is controlled to be a third flow rate that is a flow rate smaller than the second flow rate. To do.

[0013]

In the refrigeration system, for example, when the refrigerant circulation amount in the refrigeration cycle is large, the suction pressure at the start of the scroll compressor becomes high. On the other hand, when the refrigerant circulation amount in the refrigeration cycle is small, the suction pressure at the start of the scroll compressor becomes low.

Therefore, the injection flow rate at the initial stage of starting the scroll compressor is controlled according to the suction pressure at the time of starting the scroll compressor. For example, when the suction pressure is higher than a predetermined value, the refrigerant circulation amount is large. Therefore, by increasing the injection flow rate, it is possible to correct the delay in the control of the injection amount with respect to the temperature rise inside the scroll compressor at the initial stage of startup.

Similarly, when the suction pressure is lower than a predetermined value, it is judged that the refrigerant circulation amount is small, and the injection flow rate is reduced to restrict the inflow of the refrigerant more than necessary and to suppress the compressor at the initial stage of startup. It can suppress the internal cold. With these, according to the discharge gas temperature control method of the scroll compressor of the present refrigeration system, it is possible to control the inside of the compressor within a constant temperature range even in a transient state where the operating state suddenly changes such as when the scroll compressor starts. .

When the ambient temperature of the scroll compressor (hereinafter referred to as ambient temperature) is higher than a predetermined temperature,
By increasing the injection flow rate at the initial startup of the scroll compressor, the temperature rise inside the scroll compressor can be suppressed.

Further, when the surface temperature of the scroll compressor at startup (hereinafter referred to as surface temperature) is higher than the ambient temperature by a predetermined value or more, the flow rate of the refrigerant to be injected at the initial startup of the scroll compressor is changed. By setting the flow rate to a predetermined value or more, it is possible to suppress the temperature rise inside the scroll compressor at the so-called hot start, and it is possible to prevent the scroll compressor from being overcooled at the so-called cold start.

As described above, when the method for controlling the discharge gas temperature of the scroll compressor of the refrigerating apparatus of the present invention is used, the injection flow rate can be controlled according to the state of the suction pressure when the scroll compressor is started. It is possible to control the temperature inside the scroll compressor within an appropriate temperature range even in a transient state where the operating state changes suddenly.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigeration cycle system diagram showing a scroll compressor of a refrigeration system according to a first embodiment of the present invention. The scroll compressor of this refrigeration system includes a scroll compressor 1, a small-capacity capillary 7 serving as a flow path for injecting a portion of high-pressure liquid refrigerant into an intermediate pressure chamber in the middle of compression in the scroll compressor 1, and a large-capacity capillary. It has a capillary 8, an injection solenoid valve 5 for opening and closing the inflow of high-pressure liquid refrigerant into the small-capacity capillary 7, and an injection solenoid valve 6 for opening and closing the inflow of high-pressure liquid refrigerant into the large-capacity capillary 8. . Further, the scroll compressor of the present refrigeration system has a condenser 2, an expansion valve 3 and an evaporator 4 which together with the scroll compressor 1 constitute a refrigeration cycle. Here, the small-capacity capillary 7 has a smaller capacity than the large-capacity capillary 8.

Furthermore, the scroll compressor of the present refrigerating apparatus detects a pressure detector (not shown) for detecting the suction pressure of the scroll compressor 1 (hereinafter, simply referred to as suction pressure) and the surface temperature of the scroll compressor 1. It has a first temperature detector (not shown), a second temperature detector (not shown) that detects the ambient temperature of the scroll compressor 1, and a third temperature detector (not shown) that detects the discharge gas temperature of the scroll compressor 1. ing.

Next, the operation of this embodiment will be described.
FIG. 2 is a flowchart showing a discharge gas temperature control method for the scroll compressor of the refrigerating apparatus shown in FIG. First,
It is determined whether or not the suction pressure at the time of starting the scroll compressor 1 is higher than a predetermined reference value (S1). If the suction pressure is higher than the predetermined reference value, the solenoid valves 5 and 6 are opened at substantially the same time as the start of the scroll compressor 1 to make the injection amount "large" (S8).

On the other hand, when the suction pressure is lower than the predetermined reference value, it is determined whether the ambient temperature is higher than the predetermined temperature (S2). Here, when the ambient temperature is higher than the predetermined temperature, only the solenoid valve 5 is opened in synchronization with the scroll compressor 1 to set the injection amount to "small amount" (S6).

If the ambient temperature is lower than the predetermined temperature in step 2, it is determined whether the surface temperature of the scroll compressor 1, that is, the body temperature is substantially the same as the ambient temperature (S).
3). Whether or not they are substantially the same is determined by whether or not the difference between the surface temperature and the ambient temperature is within a predetermined value. Here, when the surface temperature and the ambient temperature are not substantially the same, that is, when the scroll compressor 1 that has been temporarily stopped is restarted before the temperature of the compressor is almost decreased, only the solenoid valve 5 is operated. The scroll compressor 1 is opened in synchronization with the scroll compressor 1 to set the injection amount to "small amount" (S6).

If the surface temperature and the ambient temperature are substantially the same in step 3, that is, if the scroll compressor 1 is stopped for a long time and then the scroll compressor 1 is started, The injection amount is set to "zero" by keeping both the solenoid valves 5 and 6 closed (S4). Then, it is judged whether or not the discharge gas temperature of the scroll compressor 1 has reached a temperature lower than a predetermined temperature by a temperature α (S4), and when it reaches that temperature, only the solenoid valve 5 is scroll-compressed. It is opened in synchronization with the machine 1 and the injection amount is set to "small amount" (S6).

After that, when the discharge gas temperature of the scroll compressor 1 rises to a predetermined temperature (S7), the solenoid valve 5,
Open 6 and set the injection amount to "Large" (S
8). The various judgments or controls described above can be easily realized by using control means such as a microcomputer.

As a result, the scroll compressor of the present refrigerating apparatus sets the injection amount at the time of startup of the scroll compressor 1 in accordance with the suction pressure, ambient temperature, surface temperature, and discharge gas temperature at the time of startup to "zero", " Since it can be changed to "a small amount" or "a large amount", the temperature inside the compressor can be made appropriate even in a transient operation such as the start-up of the scroll compressor 1, and the scroll of the refrigeration system is highly reliable. It is possible to operate the compressor, and it is possible to reduce power consumed unnecessarily in the initial stage of starting the scroll compressor.

In the above embodiment, the injection amount is controlled depending on whether or not each detected temperature has reached a predetermined temperature. For example, the change state of each detected temperature, that is, the rising slope of the detected temperature, etc. It is also effective to determine the solenoid valve control according to, or to determine the solenoid valve control according to the discharge gas superheat degree consisting of the discharge pressure and the discharge gas temperature.

On the other hand, in the prior art, for example, there is a control in which the solenoid valve 5 is opened when the discharge gas temperature of the scroll compressor 1 reaches a certain temperature, and the solenoid valve 6 is opened when the temperature further rises. In this method, when the suction pressure at start-up is low, the refrigerant circulation amount is small, and when the compressor itself is cold, the surface temperature rises considerably behind the rise in the internal temperature of the compressor. By the time the temperature reaches the temperature at which injection is required, the internal temperature rises considerably, which is too late for injection.

Further, in the prior art, for example, control is performed such that the solenoid valve 5 is opened at the same time as the compressor is started regardless of the discharge gas temperature of the scroll compressor 1, and the solenoid valve 6 is opened when the temperature exceeds a certain temperature. There is something to do. With this method,
In order to prevent the injection timing delay, it is necessary to perform a certain amount of injection and a certain amount of injection at startup. Therefore, for example, when the engine is started when the ambient temperature is low, an unnecessary amount of injection flows in, which consumes unnecessary power for driving the scroll compressor 1 and in particular possesses lubricating oil on the discharge side. However, there is a drawback that the discharged cooling medium melts into the lubricating oil and deteriorates the lubricating performance.

Next, a second embodiment according to the present invention will be described. FIG. 3 is a refrigeration cycle system diagram showing a scroll compressor of a refrigeration system according to a second embodiment of the present invention.
In addition, in the scroll compressor of the present refrigeration system, the same components as those of the scroll compressor of the refrigeration system shown in FIG.

The difference between the scroll compressor of the present refrigerating apparatus and the scroll compressor of the refrigerating apparatus shown in FIG. 1 is that in the present apparatus, the injection solenoid valves 5, 6, small capacity capillary 7 and large capacity capillary 8 in FIG. Instead of the above, a flow rate adjusting valve 9 is provided.

The flow rate adjusting valve 9 is a valve capable of smoothly adjusting the flow rate of injection, and is a controller such as a microcomputer (not shown) or a mechanical control means such as a scroll compressor of the refrigerating apparatus shown in FIG. Controlled. Then, by controlling the flow rate adjusting valve 9 as shown in the flowchart of FIG. 2, the suction pressure, the ambient temperature, the surface temperature, and the discharge when the scroll compressor 1 is started, like the scroll compressor of the refrigeration apparatus shown in FIG. The injection amount at the time of startup can be changed smoothly according to the gas temperature.

Next, a third embodiment according to the present invention will be described. FIG. 4 is a refrigeration cycle system diagram showing a scroll compressor of a refrigeration system according to a third embodiment of the present invention.
In addition, in the scroll compressor of the present refrigeration system, the same components as those of the scroll compressor of the refrigeration system shown in FIG. Here, the twin scroll compressor 14 includes a scroll wrap 14 that serves as two compression chambers.
It has ab, 14bb and two electric motors 14aa, 14ba for rotating the scroll wrap, respectively.

The difference between the scroll compressor of the present refrigerating apparatus and the scroll compressor of the refrigerating apparatus shown in FIG. 1 is that the apparatus shown in FIG. 1 has a small capacity capillary 7 and a large capacity capillary 8 which are element parts for adjusting the injection amount. , Are connected in parallel, but in this device, the capillary 11 and the capillary 13a, which are element parts for adjusting the injection amount,
13b is connected in series.

In the scroll compressor of the present refrigeration system, by closing both the solenoid valve 10 and the solenoid valve 15, the injection flow rate becomes "zero" and the solenoid valve 10
The injection flow rate is "small" by closing only the valve, and the injection flow rate is "high" by opening both the solenoid valve 10 and the solenoid valve 15.

The scroll compressor of the present refrigerating apparatus controls each solenoid valve in the same manner as the scroll compressor of the refrigerating apparatus shown in FIG. 1, so that the scroll compressor of the refrigerating apparatus shown in FIG. The injection amount at the time of startup of the scroll compressor 14 can be changed according to the suction pressure, ambient temperature, surface temperature, and discharge gas temperature at startup.

As a result, the scroll compressor of the present refrigeration system, like the scroll compressor of the refrigeration system shown in FIG. 1, keeps the temperature inside the compressor even during transient operation such as when the scroll compressor 14 is started. This makes it possible to operate the scroll compressor of the refrigeration system with high reliability and reduce the power consumed unnecessarily in the initial stage of starting the scroll compressor.

In the above embodiment, when the surface temperature at the time of starting the scroll compressor is high, that is, at the time of hot start, there is little delay in the temperature change of the surface temperature from the temperature change inside the compressor, and conversely. When the surface temperature of the scroll compressor is cold at the time of starting, that is, at the time of cold start, the delay in temperature change between the inside of the compressor and the surface temperature becomes large. Therefore, the discharge gas temperature can be controlled more satisfactorily by changing the timing for controlling the injection flow rate in accordance with the difference between the ambient temperature and the surface temperature when the scroll compressor is activated.

[0040]

As described above, according to the present invention, the scroll compressor according to at least one of the suction pressure at start-up, the surface temperature of the compressor, and the ambient temperature of the scroll compressor is used. (EN) A method and a device for controlling the discharge gas temperature of a scroll compressor of a refrigeration system, which can reduce the temperature fluctuation inside the scroll compressor even when the operating state changes suddenly because the liquid injection flow rate at the initial startup is controlled. can do.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle system diagram showing a refrigeration apparatus according to a first embodiment of the present invention.

2 is a flowchart showing a method for controlling a discharge gas temperature of the refrigerating apparatus shown in FIG.

FIG. 3 is a refrigeration cycle system diagram showing a refrigeration apparatus according to a second embodiment of the present invention.

FIG. 4 is a refrigeration cycle system diagram showing a refrigeration apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Scroll Compressor 2 Condenser 3 Expansion Valve 4 Evaporator 5 Liquid Injection Solenoid Valve 6 Liquid Injection Solenoid Valve 7 Small Capacity Capillary 8 Large Capacity Capillary 9 Flow Control Valve 10 Solenoid Valve 11, 13a, 13b Capillary 12a, 12b Reversed Stop valve 14 Twin type scroll compressor 15 Solenoid valve

Claims (7)

[Claims] 1. A discharge gas temperature control for a scroll compressor of a refrigeration system for controlling a discharge gas temperature of the scroll compressor by injecting a part of the liquid refrigerant into an intermediate pressure chamber of the scroll compressor for compressing the refrigerant. In the method, controlling the flow rate of the refrigerant to be injected at the initial startup of the scroll compressor according to at least one of the suction pressure at startup of the scroll compressor, the surface temperature of the compressor, and the ambient temperature. A method for controlling a discharge gas temperature of a scroll compressor of a refrigeration system, the method comprising: 2. The method for controlling a discharge gas temperature of a scroll compressor of a refrigeration apparatus according to claim 1, wherein the suction pressure at the time of starting the scroll compressor is higher than a predetermined pressure,
A method for controlling a discharge gas temperature of a scroll compressor of a refrigeration system, characterized in that a flow rate of a refrigerant injected at an initial stage of starting the scroll compressor is set to a flow rate of a predetermined value or more. 3. The method for controlling a discharge gas temperature of a scroll compressor of a refrigeration apparatus according to claim 1, wherein the ambient temperature at the time of starting the scroll compressor is higher than a predetermined temperature,
A method for controlling a discharge gas temperature of a scroll compressor of a refrigeration system, characterized in that a flow rate of a refrigerant injected at an initial stage of starting the scroll compressor is set to a flow rate of a predetermined value or more. 4. The method for controlling a discharge gas temperature of a scroll compressor of a refrigerating apparatus according to claim 1, wherein when the surface temperature of the scroll compressor at startup is higher than an ambient temperature by a predetermined value or more, A method for controlling a discharge gas temperature of a scroll compressor of a refrigeration system, characterized in that a flow rate of a refrigerant injected at a start-up of the scroll compressor is set to a flow rate of a predetermined value or more. 5. The method for controlling a discharge gas temperature of a scroll compressor of a refrigeration apparatus according to claim 1, wherein when the suction pressure at the start of the scroll compressor is higher than a predetermined pressure,
The flow rate of the refrigerant to be injected at the initial startup of the scroll compressor is a first flow rate that is a predetermined flow rate, while the suction pressure is lower than a predetermined pressure, and the ambient temperature at startup of the scroll compressor is When the temperature is higher than a predetermined temperature, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is the second flow rate which is a flow rate smaller than the first flow rate, while the suction pressure is lower than the predetermined pressure. And, if the ambient temperature is lower than a predetermined temperature, and the difference between the ambient temperature and the surface temperature at the time of starting the scroll compressor is a predetermined value or less, at the initial startup of the scroll compressor. Discharge gas of a scroll compressor of a refrigeration system, characterized in that a flow rate of a refrigerant to be injected is a third flow rate which is a flow rate smaller than the second flow rate. Degree control method. 6. A discharge gas temperature control of a scroll compressor of a refrigerating apparatus for controlling a discharge gas temperature of the scroll compressor by injecting a part of the liquid refrigerant into an intermediate pressure chamber of the scroll compressor for compressing the refrigerant. In the method, refrigeration characterized by controlling the flow rate of the refrigerant to be injected at the initial stage of starting the scroll compressor according to the degree of superheat of the discharge gas determined from the discharge pressure and the discharge gas temperature at the start of the scroll compressor. Method for controlling discharge gas temperature of scroll compressor of device. 7. A discharge gas temperature control for a scroll compressor of a refrigerating apparatus for controlling a discharge gas temperature of the scroll compressor by injecting a part of the liquid refrigerant into an intermediate pressure chamber of the scroll compressor for compressing the refrigerant. In the device, a pressure detector that detects an intake pressure of the scroll compressor, a first temperature detector that detects a surface temperature of the scroll compressor, and a second temperature detector that detects an ambient temperature of the scroll compressor. A flow rate adjusting means for adjusting the flow rate of the injected refrigerant, and a control means for controlling the flow rate adjusting means based on the detection results of the pressure detector, the first temperature detector, and the second temperature detector. And a control means for starting the scroll compressor when the suction pressure at the time of starting the scroll compressor is higher than a predetermined pressure. The flow rate of the refrigerant injected at the initial stage is the first flow rate, which is a predetermined flow rate, while the suction pressure is lower than the predetermined pressure and the ambient temperature at the time of starting the scroll compressor is higher than the predetermined temperature. In this case, the flow rate of the refrigerant injected at the initial startup of the scroll compressor is the second flow rate which is smaller than the first flow rate, while the suction pressure is lower than a predetermined pressure and the ambient temperature is Is lower than a predetermined temperature, and, if the difference between the ambient temperature and the surface temperature at the start of the scroll compressor is a predetermined value or less, the flow rate of the refrigerant to be injected at the initial startup of the scroll compressor. A discharge gas temperature control device for a scroll compressor of a refrigeration system, which is controlled to a third flow rate which is a flow rate smaller than the second flow rate.