U.S. patent application number 10/508239 was filed with the patent office on 2005-10-13 for position sensor and a linear compressor.
Invention is credited to Puff, Rinaldo.
Application Number | 20050226733 10/508239 |
Document ID | / |
Family ID | 39183053 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050226733 |
Kind Code |
A1 |
Puff, Rinaldo |
October 13, 2005 |
Position sensor and a linear compressor
Abstract
The present invention relates to a sensor, particularly useable
for detecting the position of a compressor actuator (2), the
actuator (2) being axially displaceable in a cylinder bore (3), the
sensor comprising a probe (4) and a hermetic terminal (7)
associable with each other, the probe (4) being positioned inside
the cylinder bore (3), the hermetic terminal (7) being connected to
a control circuit (8) and, further, to a linear compressor provided
with an actuator (2), a cylinder bore (3) and a head (5), the
actuator being axially displaceable inside the cylinder bore (3),
the linear compressor comprising a position sensor comprising a
probe (4) and a hermetic terminal (7) associable with each other,
the probe (4) being positioned inside the cylinder bore (3), the
hermetic terminal (7) being connected to a control circuit (8).
Inventors: |
Puff, Rinaldo;
(Joinville-Sc, BR) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Family ID: |
39183053 |
Appl. No.: |
10/508239 |
Filed: |
April 26, 2005 |
PCT Filed: |
December 13, 2002 |
PCT NO: |
PCT/BR02/00184 |
Current U.S.
Class: |
417/63 ; 417/437;
417/44.1 |
Current CPC
Class: |
F04B 35/045 20130101;
F04B 2201/0201 20130101 |
Class at
Publication: |
417/063 ;
417/437; 417/044.1 |
International
Class: |
F04B 049/06; F04B
049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2002 |
BR |
PI 0200898-0 |
Claims
1. A sensor, particularly useable in detecting the position of an
actuator (2) of a compressor in which the actuator (2) is axially
displaceable inside a cylinder bore (3), the sensor being
characterized by comprising: a probe (4) and a hermetic terminal
(7) to be arranged in a head (5) of the cylinder (5), the probe (4)
being positioned inside the cylinder bore (3), the probe (4) and
the hermetic terminal (7) being associable with each other by means
of the contact of the actuator (2) with the probe (4), the hermetic
terminal (7) being connected to a control circuit (8).
2. A sensor according to claim 1, characterized in that the probe
(4) comprises a contact projection (10) arranged between a first
end (11) fixed between a head (5) and the cylinder bore (3) and a
second end (12).
3. A sensor according to claim 2, characterized in that the second
end (12) comprises a contact region (9).
4. A sensor according to claim 3, characterized in that the contact
region (9) comprises a substantially curved profile.
5. A sensor according to claim 4, characterized in that the contact
projection (10) and the contact region (9) are arranged on
different planes.
6. A sensor according to claim 5, characterized in that the
hermetic terminal (7) is positioned in an insulated cavity (15)
arranged in the compressor hood (5).
7. A sensor according to claim 6, characterized in that the
hermetic terminal (7) is positioned at a backset distance (d) from
the head (5).
8. A sensor according to claim 7, characterized in that the probe
(4) and the hermetic terminal (7) are associable with each other by
means of the contact of the contact projection (10) with the
hermetic terminal (7).
9. A sensor according to claim 8, characterized in that the contact
of the contact projection (10) with the hermetic terminal (7) forms
an electric contact with the control circuit (8).
10. A sensor according to claim 9, characterized in that the
contact region (9) is contactable by the actuator (2).
11. A sensor according to claim 10, characterized in that the
contact of the contact projection (10) with the hermetic terminal
(7) is substantially simultaneous with the contact of the actuator
(2) with the contact region (9).
12. A sensor according to claim 11, characterized in that the
substantially simultaneous contact of the contact projection (10)
with the terminal (7) and of the actuator (2) with the contact
region (9) takes place substantially at a first control point
(6).
13. A sensor according to claim 11, characterized in that the
substantially simultaneous contact of the contact projection (10)
with the terminal (7) and of the actuator (2) with the contact
region (9) takes place at a second control point (6').
14. A sensor according to claim 12 or 13, characterized in that the
control circuit (8) comprises an electric circuit that includes a
source of electric voltage (21) and a resistor (22), both connected
in series with the hermetic terminal and with the head (5), the
electric circuit being closed when the contact projection (10)
contacts the hermetic terminal (7).
15. A sensor according to claim 12 or 13, characterized in that the
control circuit (8) comprises an electric circuit that includes a
source of electric voltage (21) and a resistor (22), both connected
in series with the hermetic terminal (7) and with the actuator (4),
the electric circuit being closed when the contact projection (10)
contacts the hermetic terminal (7).
16. A linear compressor provided with an actuator (2), a cylinder
bore (3) and a head (6), the actuator being axially displaceable
inside the cylinder bore (3), the linear compressor being
characterized by comprising: a position sensor comprising a probe
(4) and a hermetic terminal (7), the hermetic terminal (7) being
arranged in the head (5) and the probe (4) being positioned inside
the cylinder bore (3), the probe (4) and the hermetic terminal (7)
being associable with each other by means of the contact of the
actuator (2) with the probe (4), the hermetic terminal (7) being
connected to a control circuit (8).
17. A compressor according to claim 16, characterized in that the
probe (4) comprises a contact projection (10) arranged between a
first end (11) fixed between the head (5) and the cylinder bore (3)
and a second end (12).
18. A compressor according to claim 17, characterized in that the
second end (12) of the probe (4) comprises a contact region
(9).
19. A compressor according to claim 18, characterized in that the
contact region (9) comprises a substantially curved profile.
20. A compressor according to claim 19, characterized in that the
contact projection (10) and the contact region (9) are arranged on
different planes,
21. A compressor according to claim 20, characterized in that the
hermetic terminal (7) is positioned in an insulated cavity (15)
arranged in the head (5).
22. A compressor according to claim 21, characterized in that the
hermetic terminal (7) is positioned at a backset distance (d) from
the head (5).
23. A compressor according to claim 22, characterized in that the
probe (4) and the hermetic terminal (7) are associable with each
other by means of contact of the contact projection (10) with the
hermetic terminal (7).
24. A compressor according to claim 23, characterized in that the
contact of the contact projection (10) with the hermetic terminal
(7) forms an electric contact with the control circuit (8).
25. A compressor according to claim 24, characterized in that the
contact region (9) is contactable by the actuator (2).
26. A compressor according to claim 25, characterized in that the
contact of the contact projection (10) with the hermetic terminal
(7) is substantially simultaneous with the contact of the actuator
(2) with the contact region (9).
27. A compressor according to claim 26, characterized in that the
substantially simultaneous contact of the contact projection (10)
with the terminal (7) and of the actuator (2) with the contact
region (9) takes place at a first control point (6).
28. A compressor according to claim 26, characterized in that the
substantially simultaneous contact of the contact projection (10)
with the terminal (7) and of the actuator (2) with the contact
region (9) takes place at a second control point (6').
29. A compressor according to claim 27 or 28, characterized in that
the control circuit (8) comprises an electric circuit that includes
a source of electric voltage (21) and a resistor (22), both in
series with the hermetic terminal (7) and with the head (5), the
electric circuit being closed when the contact projection (10)
contacts the hermetic terminal (7).
30. A compressor according to claim 27 or 28, characterized in that
the control circuit (8) comprises an electric circuit that includes
a source of electric voltage (21) and a resistor (22), both
connected in series with the hermetic terminal (7) and with the
actuator (2), the electric circuit being closed when the contact
projection (10) contacts the hermetic terminal (7).
Description
[0001] The present invention relates to a position sensor
applicable to a linear compressor and used for detecting the
position of the compressor actuator, as well as to a linear
compressor provided with a position sensor.
DESCRIPTION OF THE PRIOR ART
[0002] A linear compressor basically comprises an actuator or
piston that is axially displaced inside a cylinder bore and that
has the function of compressing the gas during the cooling cycle.
In order to allow this gas to go in and out,the compressor is
further provided with a head comprising a suction valve and a
discharge valve. This head is located at the end of the actuator
stroke.
[0003] The actuator, together with a magnetic component and a
resonant spring, forms a resonant assembly that is driven by a
linear motor. This resonant assembly develops a linear movement,
and the axial displacement of the actuator provides the necessary
compression of the gas.
[0004] If there are variations in operation or variations in the
feed voltage of the compressor, the resonant assembly comes out of
its normal course of movement and is displaced beyond the permitted
limit, causing the actuator to collide with the compressor head.
This abnormality causes noises and damage to the compressor,
especially to the valve head.
[0005] One can try to solve this problem by controlling the voltage
levels applied to the motor or by controlling the displacement of
the actuator in the bored-through body, in order for the latter not
to damage the head.
[0006] This control over the displacement of the actuator may also
be effected by positioning the sensor on the head, so that it will
signal or interrupt the energy supply upon detection of the
beginning of collisions of the actuator against the head. Although
this solution stops the collision of the activator, it does not
avoid it from damaging the head, mainly if a sensor failure
happens.
[0007] Another solution foreseen for controlling the course of
displacement of the actuator inside the cylinder bore consists in
using a position sensor, usually inductive transducers that detect
the passage of the actuator by a determined control point. The
disadvantage of this solution lies in the high cost of the device
used and the difficulty in installing and maintaining it, which
causes the final cost of the compressor to rise.
[0008] PI 0001404-4 relates to a position sensor placed close to
the compressor head and capable of signaling the passage of the
actuator by a maximum recommendable point, in order to prevent it
from bumping against the head at the moments of variations in its
operation. This sensor is made of an electrically conductor
material, which upon receiving contact of the actuator emits an
electric signal to a control circuit, which prevents the actuator
from continuing its advance towards the valve head.
[0009] However, in order for this solution to be possible, the
sensor has to be insulated from the rest of the compressor, as for
instance, from the cylinder bore and from the head, so that the
circuit can remain open until the actuator leans against the
sensor. In the embodiment to which PI 0001404-4 refers, this
insulation may be effected by means of joints made of a sealing
material and electrically inert, placed at the portion in which the
sensor is in contact with the compressor or all over the head. In
this regard, the sensor is manufactured from a blade that
constitutes the valve and that is positioned on the head.
[0010] The use of sealing joints requires an adequate adjustment in
the positioning of the valve blade that has the sensor, of the head
and of the cylinder bore.
[0011] As described in PI 0101976-7, another proposed solution
consists in using a sensor plate independent of the suction valve,
but with the same external profile, the electric insulation of this
plate being effected by depositing upon it a painting layer of the
epoxy or varnish type, or another type having electric resistance
characteristics. The main disadvantages of this solution lie in the
need for electric insulation throughout the sensor place and to the
possibility of escape of current due to the area of the sensor
plate.
OBJECTIVES OF THE INVENTION
[0012] The objective of the present invention is to provide a
sensor capable of detecting and controlling the position of the
actuator close to the head and to the compressor valves, in order
to prevent the actuator from bumping against the head during a
failure in its functioning, without this raising the costs of
manufacturing the compressor.
BRIEF DESCRIPTION OF THE INVENTION
[0013] The objective of this invention is achieved by means of a
sensor, particularly useable in detecting the position of an
actuator of a compressor in which the actuator is axially
displaceable inside a cylinder bore, the sensor comprising a probe
and a hermetic terminal to be arranged in a head of the cylinder,
the probe being positioned inside the cylinder bore, the probe and
the hermetic terminal being associable with each other by means of
the contact of the actuator with the probe, the hermetic terminal
being connected to a control circuit.
[0014] The objectives of this invention are also achieved by means
of a linear compressor provided with an actuator, a cylinder bore
and a head, the actuator being axially displaceable inside the
cylinder bore, the linear compressor comprising a position sensor
comprising a probe and a hermetic terminal, the hermetic terminal
being arranged in the head and the probe being positioned inside
the cylinder bore, tho probe and the hermetic terminal being
associable with each other by means of the contact of the actuator
with the probe, the hermetic terminal being connected to a control
circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will now be described in greater
detail with reference to an embodiment represented in the drawings.
The figure shows:
[0016] FIG. 1--Is a schematic cross-section view of the linear
compressor and of the sensor of the present invention.
DETAILED DESCRIPTION OF THE FIGURES
[0017] According to a preferred embodiment and as can be seen In
FIG. 1, the linear compressor comprises an actuator 2, which is
displaceable inside a cylinder bore 3, and a head 5 positioned at
the end of the course of displacement of the actuator 2 and
comprising the suction valve 17 and discharge valve 17'.
[0018] The position sensor comprises a probe 4, positioned inside
the cylinder bore 3, and a hermetic terminal 7, connected to a
control circuit 8.
[0019] The probe 4 is thin and flexible and may be constituted by a
metallic blade, which may be replaced by a cylindrical, massive or
hollow piece, or else may have another appropriate shape. This
probe 4 comprises a first end 11, a contact projection 10, a
contact region 9 and a second end 12. The first end 11 is fixed
between the aid 5 and the cylinder bore 3, while the second end 12
is free from engagement.
[0020] In a variation of fixation of this probe 4, it is fixed on
the actuator 2 itself, the first end 11 being fixed on the face of
the actuator 2, while the second end 12 remains free from fixation
or engagement.
[0021] The contact projection 10 is formed from a bending of the
body of the probe 4. This projection 10 is arranged between the
first end 11 and the second end 12, so as to remain aligned with
the hermetic terminal 7.
[0022] The contact region 9 is arranged at the second end 12 and
has a substantially curved profile reducing the friction during the
contact of the actuator 2 with this region 9.
[0023] The contact projection 10 and the contact region 9 are
arranged on different planes. With respect to the head 5, the
contact projection 10 has a null spacing since it is permanently in
contact with the head 5, as shown in detail A, while the contact
region 9 has a spacing h, as can be seen in detail B of FIG. 1.
[0024] The hermetic terminal 7 will be positioned in an insulated
cavity 15, filled with an insulating material 16 and arranged on
the head 5 of the compressor.
[0025] According to detail A of FIG. 1, the hermetic terminal 7 is
mounted in the cavity 15 at a backset distance d with respect to
the surface of the head 5 facing the interior of the cylinder bore
3. In this way, the positioning of the hermetic terminal 7 on the
head 5 should be carried out in such a way that the terminal 7 will
be aligned to the contact projection 10, since the probe 4 and the
hermetic terminal 7 are associable with each other by means of the
contact of the contact projection 10 with the hermetic terminal 7.
Thus, the end of the terminal 7 that should contact the contact
projection 10 is preferably plane and parallel to the face of the
head 5 in order for the curvature of the contact position 10 to
obtain satisfactory contact with this end of the terminal 7.
However, other variations in shape of this end of the terminal 7
are foreseen, as for example, the shape of an inclined plane or
chamfer with an angle of inclination coinciding with that of the
probe 4, among others.
[0026] In addition, the hermetic terminal 7 is connected to the
control circuit 8, formed by an electric circuit comprising a
source of electric voltage 21, preferably of direct current, and a
resistor 22, both connected in series with the hermetic terminal 7
and the head 5, as illustrated in detail C of FIG. 1. In one of the
possible variations of this circuit, an association of the source
21 and the resistor 22 in series with the terminal 7 and with the
actuator 2 is foreseen.
[0027] When the actuator 22, in its axial displacement, reaches a
determined distance from the head 6, that is to say, a first
control point 6, the actuator 2 contacts the contact region 9 of
the probe 4, displacing it as far as the second control point 6'
arranged at a displacement distance H from the first control point
6.
[0028] When the contact region 9 reaches the second control point
6', the contact projection 10 is physically in contact with the
hermetic terminal 7, forming an electric contact with the control
circuit 8. In this way, the Contact of the actuator 2 with the
contact region 9 is substantially simultaneous with the contact of
the contact projection 10 with the hermetic terminal 7.
[0029] Said electric contact formed with the control circuit 8,
that is, the indication that the actuator 2 has reached the first
control point 6 and the second control point 6' causes, the voltage
level measured at the terminals. (not shown) close to the resistor
22 to pass from the logical level "0" to the logical level "1".
This variation is read by the control circuit 8, which may further
include an electronic circuit capable of interpreting this
signaling, which corrects the path of the actuator 2, thus
preventing it from bumping against the head 5, that is to say, it
causes the maximum displacement of the actuator 2 toward the head 5
to return to below the first control point 6.
[0030] Once this excess in displacement of the actuator 2 is
corrected, the contact region 9 is again positioned at the same
level as the first control point 6. For this purpose, the probe 4
should preferably be made from a material having an elastic
deformation zone that embraces the amplitude of this deformation
which the probe 4 undergoes during this displacement of the region
9 from the first control point 6 to the second control point 6'.
This is because, after the efforts have ceased, the region 9 should
necessarily return to its initial position, that is to say,
coinciding with the first control point 6.
[0031] Thus, the material employed in constructing this probe 4,
independently of its shape and profile, should be little
susceptible to hysteresis, that is to say, to the residual
deformations along the time of use of the sensor.
[0032] The present invention has the advantage of meeting the need
for painting the sensor plate in an attempt to insulate it from the
rest of the components of the compressor, thus increasing the
reliability of the insulation of the probe 4 and providing a more
precise control over the position of the actuator 2.
[0033] Another advantage of the present invention lies in the low
cost of the hermetic terminal 7 and in its great availability on
the market. For this reason, the applied modifications do not
render the final compressor assembly expensive.
[0034] A preferred embodiment having been described, one should
understand that the scope of the present invention embraces other
possible variations, being limited only by the contents of the
accompanying claims, which include the possible equivalents.
* * * * *