Apparatus and method for controlling operation of reciprocating compressor

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reciprocating compressor and, more particularly, to an apparatus and method for controlling an operation of a reciprocating compressor.

2. Description of the Background Art

In general, a reciprocating compressor is to compress a refrigerant circulating inside a cooling device as a piston is linearly and reciprocally moving inside a cylinder. The reciprocating compressor can be roughly divided into a recipro type and a linear type depending on how the piston is driven.

The recipro type reciprocating compressor is that a crank shaft is coupled to a rotating motor and a piston is coupled to the crank shaft so that the piston can be linearly and reciprocally moved by using a rotational force of the rotating motor.

The linear type reciprocating compressor is that the piston is directly connected to a linear motor to allow the piston to be linearly and reciprocally moved by using the linear movement of the linear motor.

The linear type reciprocating compressor does not need such a crank shaft converting the rotational motion to a linear motion. Thus, with a relatively smaller friction loss, the linear type reciprocating compressor has a great merit of having high compression efficiency compared to a general compressor.

In addition, a compression ratio of the linear type reciprocating compressor can be controlled by controlling a voltage applied to the motor, so that freezing capacity of a cooling device can be controlled.

An apparatus for controlling an operation of the reciprocating compressor will now be described with reference to FIG. 1.

FIG. 1 shows the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with the conventional art.

As shown in FIG. 1, the conventional apparatus for controlling an operation of a reciprocating compressor includes: a voltage detector 30 for detecting a voltage applied to a reciprocating compressor and outputting the detected voltage; a current detector 20 for detecting a current applied to the reciprocating compressor and outputting the detected current; a microcomputer 40 for calculating a stroke estimate value based on the detected voltage and current, comparing the calculated stroke estimate value with a stroke reference value, and outputting a control signal according to the compared result; and an electric circuit unit 10 for varying a stroke of the reciprocating compressor by controlling a triac (Tr1) according to the control signal of the microcomputer 40.

The apparatus for controlling an operation of the reciprocating compressor in accordance with the conventional art will now be described in detail.

First, in the reciprocating compressor 10A, a piston is moved linearly and reciprocally corresponding to a voltage applied according to a pre-set stroke reference value. Thus, since the stroke is varied, freezing capacity is controlled according to the varied stroke.

The voltage detector 30 detects a voltage applied to the reciprocating compressor 10A and outputs the detected voltage, and the current detector 20 detects a current applied to the reciprocating compressor 10A and outputs the detected current.

The microcomputer 40 calculates a stroke estimate value based on the detected voltage and current, compares the calculated stroke estimate value with the stroke reference value, and then, outputs a control signal for controlling a reciprocating compressor 10A according to the compared result.

Thereafter, the microcomputer 40 controls the stroke of the reciprocating compressor 10A by varying an ON/OFF period of the triac Tr1 of the electric circuit unit 10 through the control signal.

In detail, when the calculated stroke estimate value is smaller than the stroke reference value, the microcomputer 40 outputs a control signal to lengthen the ON period of the triac Tr1 to increase a voltage applied to the reciprocating compressor 10A through the triac Tr1. When the calculated stroke estimate value is greater than the stroke reference value, the microcomputer 40 outputs a control signal to shorten the ON period of the triac Tr1 to reduce a voltage applied to the reciprocating compressor 10A through the triac Tr1.

Accordingly, in the conventional apparatus for controlling an operation of the reciprocating compressor, the stroke of the reciprocating compressor is controlled by varying the ON/OFF period of the control signal inputted to the triac Tr1.

However, the conventional apparatus for controlling an operation of the reciprocating compressor is disadvantageous in that since the ON/OFF period of the control signal inputted to the triac is varied, a transport loss of the triac itself is made and a harmonic loss generated due to the transport loss degrade efficiency of the operation of the reciprocating compressor.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an apparatus and method for controlling an operation of a reciprocating compressor capable of enhancing operation efficiency of a reciprocating compressor by selecting one of control paths of pre-set general mode and power-saving mode according to a control signal and controlling a stroke of the reciprocating compressor through the selected control path.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for controlling an operation of a reciprocating compressor including: a microcomputer for outputting a control signal for controlling a stroke of a reciprocating compressor; and an electric circuit unit for selecting one of control paths of pre-set general mode and power-saving mode according to a control signal and controlling a stroke of the reciprocating compressor through the selected control path.

To achieve the above object, there is also provided a method for controlling an operation of a reciprocating compressor including: driving a reciprocating compressor in a general mode to control a stroke through an ON/OFF period of a triac; determining whether the reciprocating compressor can be driven in a power-saving mode; and driving the reciprocating compressor in the power-saving mode according to the determined result.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 shows the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with a conventional art;

FIG. 2 shows the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with the present invention;

FIG. 3 is a flow chart of a method for controlling an operation of the reciprocating compressor in accordance with the present invention; and

FIG. 4 is a graph showing operation efficiency according to freezing capacity of the reciprocating compressor employing the operation control apparatus in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An apparatus and method for controlling an operation of a reciprocating compressor capable of enhancing operation efficiency of a reciprocating compressor by selecting one of control paths of a general mode and power-saving mode previously set according to a control signal and controlling a stroke of the reciprocating compressor through the selected control path, in accordance with the present invention will now be described with reference to the accompanying drawings.

FIG. 2 shows the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with the present invention.

As shown in FIG. 2, an apparatus for controlling an operation of a reciprocating compressor includes: a voltage detector 30 for detecting a voltage applied to a reciprocating compressor and outputting the detecting voltage; a current detector 20 for detecting a current applied to the reciprocating compressor and outputting the detected current; a microcomputer 40 for calculating a stroke estimate value based on the detected voltage and current, comparing the calculated stroke estimate value with a stroke reference value, and outputting a control signal according to the compared result; and an electric circuit unit 10 for selecting one of previously set control paths of a general mode and a power-saving mode according to a control signal of the microcomputer 40.

In the general mode, a stroke of the reciprocating compressor is controlled by controlling an ON/OFF period of a triac connected to a main coil L1 in the reciprocating compressor.

Meanwhile, in the power-saving mode, a stroke of the reciprocating compressor is maintained at a pre-determined value by connecting a predetermined number of sub-coil L2 to the main coil L1 in the reciprocating compressor.

The method for controlling an operation of the reciprocating compressor in accordance with the present invention will now be described.

FIG. 3 is a flow chart of a method for controlling an operation of the reciprocating compressor in accordance with the present invention.

As shown in FIG. 3, the method for controlling an operation of the reciprocating compressor includes: driving a reciprocating compressor in a general mode to control a stroke of the reciprocating compressor by an ON/OFF period of a triac (step S31); determining whether the reciprocating compressor can be driven in a power-saving mode (step S32); and driving the reciprocating compressor in the power-saving mode according to the determined result.

The method for controlling an operation of the reciprocating compressor in accordance with the present invention will be described as follows.

First, as for the reciprocating compressor 10A, since the stroke is varied as the piston is linearly and reciprocally moved corresponding to a voltage applied according to a stroke reference value which has been previously set by a user, freezing capacitor is controlled according to the varied stroke (step S31).

In other words, the microcomputer 40 connects the control path of the general mode through the switching unit and controls the ON/OFF period of the triac Tr1 on the connected control path, thereby varying the stroke of the reciprocating compressor 10A. Herein, as a switching unit, a relay Ry1 is preferably used.

The electric circuit unit 10 includes control paths of the preset general mode and power-saving mode. Accordingly, one control path is selectively connected by a switching control of the relay Ry1 according to a control signal of the microcomputer 40, thereby controlling the stroke of the reciprocating compressor 10A.

The microcomputer 40 measures a temperature in a cooling device employing the reciprocating compressor to calculate a change in a temperature of the cooling device based on the measured temperature and a measured temperature of the previous period or compare the measure temperature and a pre-set threshold temperature (step S32).

Namely, when the temperature in the cooling device is changed beyond a predetermined range or higher than the threshold temperature, the microcomputer 40 controls the stroke of the reciprocating compressor in the general mode, whereas when the temperature in the cooling device is changed within the pre-set range and lower than the threshold temperature, the microcomputer 40 controls the stroke in the power-saving mode (step S33).

According to the apparatus for controlling an operation of the reciprocating compressor in accordance with the present invention, the reciprocating compressor can be driven under various conditions such as a temperature, a voltage or a current that can sense a change in load of a device employing the reciprocating compressor, as well as the above-mentioned conditions to driving in the general mode and the power-saving mode.

When the control path of the general mode is selected, the microcomputer 40 calculates a stroke estimate value based on the detected voltage and the detected current, compares the calculated stroke estimate value and the stroke reference value, and then, outputs a control signal for controlling the reciprocating compressor 10A according to the compared result.

Thereafter, the microcomputer 40 controls the stroke of the reciprocating compressor 10A by varying the ON/OFF period of the triac Tr1 of the electric circuit unit 10 through the control signal.

Namely, when the calculated stroke estimate value is smaller than the stroke reference value, the microcomputer 40 outputs a control signal to lengthen the ON period of the triac Tr1 to increase a voltage applied to the reciprocating compressor 10A through the triac Tr1. When the calculated stroke estimate value is greater than the stroke reference value, the microcomputer 40 outputs a control signal to shorten the ON period of the triac Tr1 to reduce a voltage applied to the reciprocating compressor 10A through the triac Tr1.

In the apparatus for controlling an operation of the reciprocating compressor in accordance with the present invention, when a temperature in the cooling device is rapidly changed or higher than a pre-set threshold temperature, the reciprocating compressor is driven in the general mode through the triac Tr1.

Meanwhile, when the temperature in the cooling device is changed within the predetermined range and lower than the threshold temperature, the microcomputer 40 selects the control path of the power-saving mode through the relay Ry1, namely, connects the sub-coil L2 having the predetermined number of windings to the main coil L1 in the reciprocating compressor 10A, to thereby maintain the stroke of the reciprocating compressor 10A at a predetermined value through the main coil L1 and the sub-coil L2 connected to the main coil L1 in the reciprocating compressor 10A, without using the triac Tr1.

In this manner, the apparatus for controlling an operation of the reciprocating compressor controls the reciprocating compressor in the power-saving mode when the temperature of the cooling device is changed within the predetermined range and smaller than the threshold temperature, namely, for example, while usage frequency of the cooling device is quite low or a load variation is quite small or when an ambient temperature is relatively low, whereby the cooling device employing the reciprocating compressor can be driven with the optimum power consumption.

Operation efficiency according to freezing capacity of the reciprocating compressor adopting the operation control apparatus when the reciprocating compressor is driven in the power-saving mode will now be described with reference to FIG. 4.

FIG. 4 is a graph showing operation efficiency according to freezing capacity of the reciprocating compressor employing the operation control apparatus in accordance with the present invention.

As shown in FIG. 4, in the power-saving mode of the reciprocating compressor adopting the operation control apparatus in accordance with the present invention, operation efficiency (A) is remarkably higher than operation efficiency (B) of the conventional reciprocating compressor in the general mode at the interval when the power-saving mode is driven.

As so far described, the apparatus and method for controlling an operation of a reciprocating compressor in accordance with the present invention has the following advantages.

That is, for example, one of the control path of the pre-set general mode and power-saving mode is selected according to a control signal and the stroke of the reciprocating compressor is controlled through the selected control path to thereby enhance operation efficiency of the reciprocating compressor.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.