Pumps – Condition responsive control of pump drive motor – In response to pump speed
Reexamination Certificate
2002-05-09
2004-01-27
Tyler, Cheryl J. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
In response to pump speed
C417S044100, C417S044110, C417S045000, C417S212000, C318S687000
Reexamination Certificate
active
06682310
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reciprocating motor compressor and particularly, to an apparatus and method for operation control of a reciprocating motor compressor, for controlling operation of a reciprocating motor compressor on the basis of speed information or Top Dead Center (TDC) information.
2. Description of the Background Art
Generally, by eliminating the use of a crankshaft for converting a rotary motion into a reciprocating motion, a reciprocating motor compressor has a low frictional loss, and accordingly the reciprocating motor compressor is superior to a general compressor in the compressing efficiency aspect.
When the reciprocating motor compressor is used for a refrigerator or an air conditioner, a cooling capacity of the refrigerator or the air conditioner can be controlled by varying a compression ratio of the reciprocating motor compressor by varying a stroke voltage applied to the reciprocating motor compressor. The reciprocating motor compressor will be described with reference to accompanying FIG.
1
.
FIG. 1
is a schematic block diagram illustrating the construction of an apparatus for controlling the operation of a reciprocating motor compressor in accordance with the prior art.
As depicted in
FIG. 1
, the apparatus for controlling the operation of a reciprocating motor compressor in accordance with the prior art applies a voltage detecting unit
14
for detecting a voltage applied to the reciprocating motor compressor
13
according to the variation of the stroke, and a current detecting unit
12
detects a current applied to the reciprocating motor compressor
13
according to the variation of the stroke. A microcomputer
15
calculates the stroke by using the voltage detected by the voltage detecting unit
14
and the current detected from the current detecting unit
12
, comparing the calculated stroke with the stroke reference value and outputting a switching control signal according to the comparison result. And a power supply unit
11
supplies the stroke voltage to the reciprocating motor compressor
13
by on-off controlling the supplying of AC power to the reciprocating motor compressor
13
using a triac Tr
1
controlled by the switching control signal from the micro-computer
15
. Here, the stroke of the reciprocating motor compressor
13
is varied in accordance with the voltage supplied to the motor according to the stroke reference value, and moves the piston back and forth according to the varied stroke.
Hereinafter, the operation of the apparatus for controlling the operation of the reciprocating motor compressor will be described.
First, the stroke of the reciprocating motor compressor
13
is varied in accordance with the voltage supplied to the motor according to the stroke reference value, and moves the piston back and forth according to the varied stroke. Herein, the term “stroke” means a distance over which the piston inside the reciprocating motor compressor
13
moves while performing a reciprocating motion (moving back and forth).
When the triac Tr
1
of the power supply unit
11
has a longer turn-on duration in accordance with the switching control signal outputted from the microcomputer
15
, at this time the AC turn-on power is supplied to the reciprocating motor compressor
13
, and the reciprocating motor compressor
13
operates. Herein, the voltage detecting unit
14
and the current detecting unit
12
respectively detect a voltage and a current applied to the reciprocating motor compressor
13
and respectively output the detected voltage and current to the microcomputer
15
.
The microcomputer
15
calculates the stroke by using the voltage and the current detected from the voltage detecting unit
14
and the current detecting unit
12
, compares the calculated stroke with the stroke reference value and outputs the switching control signal according to the comparison result. In more detail, when the calculated stroke value is smaller than the stroke reference value, the microcomputer
15
increases the stroke voltage supplied to the reciprocating motor compressor
13
by outputting a switching control signal for lengthening the turn-on cycle of the triac Tr
1
in the power supply unit
11
.
On the contrary, when the calculated stroke value is larger than the stroke reference value, the microcomputer
15
decreases the stroke voltage supplied to the reciprocating motor compressor
13
by outputting a switching control signal for shortening the turn-on cycle of the power supply unit
11
.
However, because the reciprocating motor compressor control apparatus according to the prior art controls the operation of the reciprocating motor compressor by comparing the calculated stroke with the stroke reference value and outputting a switching control signal to the power supply unit according to the comparison result, the operation of the reciprocating motor compressor can not be controlled accurately. In more detail, since the reciprocating motor compressor control apparatus according to the prior art has a severe non-linearity in its mechanical motion functions, the operation of the reciprocating motor compressor can not be performed precisely and accurately by a linear control method without considering the non-linearity.
In addition, in the reciprocating motor compressor control apparatus according to the prior art, when the reciprocating motor compressor is operated continually in accordance with an initial detected switching control signal, a position of the piston may deviate from TDC (Top Dead Center)≈0 due to a load variation according to changes in a refrigerator and other circumstances.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an apparatus and method for operation control of a reciprocating motor compressor, capable of compensating speed errors of the motor on the basis of the speed reference value or compensation value due to a load variation, after setting the speed value of a motor at TDC≈0 as the speed reference value.
Another object of the present invention is to provide an apparatus and method for operation control of a reciprocating motor compressor, capable of compensating TDC errors on the basis of the TDC reference value and compensation value due to a load variation, after setting the TDC value of a motor at TDC≈0 as the TDC reference value.
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 operation of a reciprocating motor compressor, including a speed detecting unit for detecting a first speed value of a motor on the basis of a current and voltage applied to the motor, a phase value detecting unit for detecting a second speed value of the motor at the inflection point of the detected phase value a speed reference value storage unit for setting the second speed value as a speed reference value and storing the value and a control unit for comparing the stored speed reference value and the first speed value detected from the speed detecting unit, outputting the corresponding comparison signals, and controlling the speed of the motor with the generated switching control signal according to the comparison signals.
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 the method for controlling operation of the reciprocating motor compressor, including the steps of detecting phase difference of a first speed value of a motor and a current applied to the motor, detecting a second speed value of the motor from an inflection point of the detected phase value and storing the value as a speed reference value and controlling speed of the motor on the basis of the speed reference value and first speed value of the motor.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there
Hwang Min-Kyu
Lee Chel Woong
Yoo Jae-Yoo
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Tyler Cheryl J.
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