Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Reexamination Certificate
1999-04-28
2001-01-23
Thorpe, Timothy S. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
C417S045000, C417S053000, C073S118040
Reexamination Certificate
active
06176683
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an output control apparatus for a linear compressor and a method of the same which make it possible to obtain a better control performance without a deviation in accordance with the type of a system based on the detected magnitude of collision strength for controlling an output of a linear compressor, and in particular to an improved output control apparatus for a linear compressor and a method of the same which are capable of implementing a high efficiency by determining an accurate control target stroke time when a piston and a discharge valve collide with each other in a compressor system and constantly controlling an output of a compressor irrespective of a load applied thereto.
2. Description of the Background Art
As a method for controlling a linear compressor, a sensor less type control method is known. In this type control method, a current and voltage are fed back based on the following Equation 1 for thereby estimating a stroke of a piston, so that the linear compressor is controlled using the thus estimated stroke of the piston.
V
=
1
α
(
V
-
R
×
i
-
L
ⅆ
i
ⅆ
t
)
(
1
)
where V represents a motor terminal voltage, v represents the speed of a movement unit, R represents a motor resistor, i represents a current, &agr; represents a motor constant, and L represents a motor inductance.
The sensorless control method controls the size of the entire stroke.
The output of the linear compressor is involved in the size of the stroke as well as the position of the top dead point.
Therefore, when the piston arrives at the top dead point, the volume formed by the upper surface of the piston and the inner wall of the cylinder is referred to as a top dead volume. In the same stroke case, if the top dead volume is small, the output is increased, and the efficiency is enhanced.
Here, the position of the piston is computed based on the following Equation (2).
x=∫vdt (2)
where x represents the motion of the movement unit.
Therefore, the output of the linear compressor is controlled by the size of the stroke and the position of the top dead point of the piston.
In the conventional art, when the output of the linear compressor is controlled using the stroke, the stroke may be constantly controlled. However, in this case, since the intermediate position of the piston is varied based on the load, it is impossible to implement a constant top dead point. Namely, a constant top dead volume is not obtained. Therefore, it is difficult to control the output of the linear compressor and to implement a high efficiency and constant output.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an output control apparatus for a linear compressor and a method of the same which make it possible to obtain a constant top dead volume irrespective of a load.
It is another object of the present invention to provide an output control apparatus for a linear compressor and a method of the same which make it possible to implement a system operation with a higher efficiency.
In order to achieve the above objects, there is a provided an output control apparatus for a linear compressor which includes a voltage controller for supplying a driving voltage for driving a compressor, a stroke computation unit for receiving a voltage and current detected by a voltage and current sensor when driving the compressor and computing a stroke based on the received voltage and current, a collision detection sensor for detecting a vibration at the time when a piston collides with a discharge valve when driving the compressor, a collision detection unit for detecting whether an abnormal signal is generated due to the vibration detected by the collision detection sensor, a microcomputer for determining a control destination stroke based on a stroke generated from the stroke computation unit, and a driving unit for outputting a voltage driving signal to the voltage controller in accordance with a control destination stroke outputted from the microcomputer.
In order to achieve the above objects, there is provided an output control method for a linear compressor which includes the steps of a first step for storing a stroke inputted, a second step for judging whether a collision occurs between a piston installed in a compressor and a discharge valve, a third step for resetting a control destination stroke based on the stroke stored in the first step when a collision is detected in the second step and controlling to obtain a reset control destination stroke, and a fourth step for obtaining a previously set control destination stroke when a collision is not detected in the second step.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.
REFERENCES:
patent: 4345442 (1982-08-01), Dorman
patent: 4613285 (1986-09-01), Sato et al.
patent: 4831785 (1989-05-01), Sigg
patent: 4842301 (1989-06-01), Feldmaier
patent: 4879502 (1989-11-01), Endo et al.
patent: 5083905 (1992-01-01), Mohn
patent: 5220259 (1993-06-01), Werner et al.
patent: 5280222 (1994-01-01), Von Der Heide et al.
patent: 5496153 (1996-03-01), Redlich
LG Electronics Inc.
Ostrolenk Faber Gerb & Soffen, LLP
Solak Timothy P.
Thorpe Timothy S.
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