Information
-
Patent Grant
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6814061
-
Patent Number
6,814,061
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Date Filed
Tuesday, September 24, 200221 years ago
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Date Issued
Tuesday, November 9, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 123 520
- 123 519
- 123 518
- 123 516
- 251 1291
- 251 12909
- 251 12915
- 137 31503
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International Classifications
-
Abstract
A canister purge valve for use in an evaporative emission control system. The valve includes a housing having an inlet port and an outlet port. The housing further includes a guide element having a bobbin section. A valve shaft is slidably mounted to the guide element, wherein the valve shaft includes a permanent magnet and a valve element. The valve element is movable between a closed position wherein the inlet port is closed and an open position wherein the inlet port is opened. A pick coil is formed on the bobbin adjacent the magnet. The pick coil generates a first magnetic field having a polarity that is oriented to cause a magnetic attraction with the magnet to move the magnet and thus the valve element to the open position. In addition, a release coil is formed on the bobbin adjacent to the magnet, wherein the release coil generates a second magnetic field having a polarity that is oriented to cause the magnet to be repelled to move the magnet and thus the valve element to the closed position.
Description
FIELD OF THE INVENTION
This invention relates to evaporative emission control systems for internal combustion engines, and more particularly, to a canister purge valve having a pick coil and a release coil which interact with a permanent magnet to selectively open and close a valve element.
BACKGROUND OF THE INVENTION
Motor vehicles having an internal combustion engine typically include an evaporative emission control system which serves to reduce fuel vapor emissions. Such systems include a vapor collection canister having carbon or other similar material which serves to absorb fuel vapors that are generated within a fuel system. A canister purge valve is located between the canister and an engine intake manifold. The canister purge valve may be opened or closed to either place the canister in fluid communication with the engine intake manifold or to isolate the canister from the engine intake manifold, respectively.
Under the appropriate conditions, the canister is purged so that fuel vapors collected within the canister do not undesirably escape into the atmosphere. This is done by opening the canister purge valve, thus enabling vacuum which is present at the engine intake manifold to draw out the fuel vapors from the canister. The fuel vapors are then used in the normal combustion process.
The canister purge valve typically includes a valve that is actuated by a solenoid having an armature and a stator. One method of opening or latching the valve is to use a coil to generate a magnetic field so as to cause the armature to magnetically “stick” to the stator. In order to release the armature, an opposing magnetic force is applied to the stator, which causes the stator to repel the armature to thus close the valve. This is typically done by reversing polarity on the coil through the use of a driver circuit known as an “H” driver. However, the use of such drivers increases costs and complexity.
SUMMARY OF THE INVENTION
The invention is directed to a solenoid for use in a canister purge valve. The valve includes a housing having an inlet port and an outlet port. The housing further includes a guide element having a bobbin section. A valve shaft is slidably mounted to the guide element, wherein the valve shaft includes a permanent magnet and a valve element. The valve element is movable between a closed position wherein the inlet port is closed and an open position wherein the inlet port is opened. A pick coil is formed on the bobbin adjacent the magnet. The pick coil generates a first magnetic field having a polarity that is oriented to cause a magnetic attraction with the magnet to move the magnet and thus the valve element to the open position. In addition, a release coil is formed on the bobbin adjacent to the magnet, wherein the release coil generates a second magnetic field having a polarity that is oriented to cause the magnet to be repelled to move the magnet and thus the valve element to the closed position.
The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, may be best understood by reference to the following description taken in conjunction with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a cross sectional view of a canister purge valve depicting an energized pick coil for opening an inlet port.
FIG. 2
is a cross sectional view of a canister purge valve depicting an energized release coil for closing the inlet port.
FIG. 3
is an illustrative depiction of the canister purge valve in an evaporative emission control system.
DETAILED DESCRIPTION OF THE INVENTION
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of
FIGS. 1-3
.
Referring to
FIG. 1
, a cross sectional view of a canister purge valve
10
in accordance with the present invention is shown. The purge valve
10
includes a housing
12
having a lower wall
14
and an internal wall
16
for forming an internal passageway
18
. Inlet port walls
20
extend from the lower wall
14
to form an inlet port
22
having a first passageway
24
which is in fluid communication with a vapor collection canister
26
(FIG.
3
). A valve seat
28
for receiving a valve element
30
is formed at the intersection of the inlet port walls
20
and the lower wall
14
. Outlet port walls
32
extend from a side wall
34
of the housing
12
to form an outlet port
36
having a second passageway
38
which is in fluid communication with an engine intake manifold
97
(FIG.
3
).
The housing
12
further includes a guide member
42
having a bobbin section
44
located between upper
46
and lower
48
flanges that extend outwardly to form a substantially C-shaped configuration. The upper
46
and lower
48
flanges each include bearings
50
for enabling movement of a shaft
52
along an axial direction. It is noted that other devices and configurations for enabling movement may be used such as bushings. The shaft
52
includes a permanent magnet
54
that is located between the upper
46
and lower
48
flanges. A lower end
56
of the shaft
52
includes the valve element
30
. In
FIG. 1
, the valve element
30
is depicted in an open position wherein the valve element
30
is spaced apart from the valve seat
28
to enable fluid communication between the inlet port
22
, the internal passageway
18
and the outlet port
36
. The valve element
30
may also be moved to a closed position wherein the valve element
30
is in contact with the valve seat
28
to thus close the inlet port
22
as will be described in relation to FIG.
2
.
A first wire
58
having first
60
and second
62
ends is wound around a section of the bobbin
44
to form a pick coil
65
. A second wire
64
having third
66
and fourth
68
ends is wound around the same section of the bobbin
44
to form a release coil
70
. The pick
64
and release
70
coils are located adjacent the magnet
54
. The second
62
and fourth
68
ends are connected to a base terminal
72
and the first
60
and third
66
ends are connected to first
74
and second
76
power terminals, respectively.
In one embodiment, the magnet
54
is oriented such that the south magnetic pole is located above the north magnetic pole. The pick coil
65
is energized by maintaining the base terminal
72
at 0 volts and the first power terminal
74
at a positive voltage such as approximately +12 volts, for example. The pick coil
65
is wound such that a magnetic field is generated having north and south magnetic poles oriented near top
82
and bottom
84
portions, respectively, of the pick coil
65
. As a result, the polarity of the magnetic field along the bobbin
44
is oriented to magnetically attract the magnet
54
, thus causing the valve element
30
to move upward to the open position as shown in FIG.
1
.
Referring to
FIG. 2
, the valve element
30
is shown in the closed position. In order to move the valve element
30
to the closed position, the pick coil
65
is de-energized. The release coil
70
is then energized by maintaining the base terminal
72
at 0 volts and the second power terminal
76
at a positive voltage such as approximately +12 volts, for example. The release coil
70
is wound such that a magnetic field is generated having south and north magnetic poles oriented near top
86
and bottom
88
portions, respectively, of the release coil
70
. As a result, the orientation of the magnetic poles along the bobbin
44
is reversed from that which occurs when the pick coil
65
is energized. This causes the magnet
54
to be repelled, thus causing the valve element
30
to move downward to the closed position as shown in FIG.
2
. As such, the polarity along the bobbin
44
is reversed without the use of expensive H drivers. In particular, the present invention enables the use of simpler and less expensive drivers commonly found in current engine electronic control units such as single ended drivers.
In order to move the valve element
30
back to the open position, the release coil
70
is de-energized. The pick coil
65
is again energized to move the valve element
30
back to the open position as described above. As such, the pick
65
and release
70
coils may be selectively energized and de-energized to cause movement of the valve element
30
between the open and closed positions. It is noted that other suitable voltages may be used to energize either the pick
65
or release
70
coils. Further, it noted that the polarity of the magnet
54
and that of the magnetic field generated by the pick
65
and release
70
coils may be correspondingly reversed as desired to enable movement of the valve element
30
between the open and closed positions.
Referring to
FIG. 3
, the purge valve
10
in accordance with the present invention is shown in an emission control system
90
. The system
90
includes a leak detection monitor
92
which is used as part of a selected on board diagnostic procedure for determining whether there is a fuel vapor leak in the system
90
that is above a predetermined level.
The canister
26
is in fluid communication with a fuel tank
96
and includes carbon or other similar material which serves to absorb fuel vapors that are generated within a fuel tank
94
and in the emission control system
90
. The canister
26
also includes a vent solenoid valve
96
which is opened under the appropriate conditions so as to place the canister
26
in fluid communication with atmospheric air through a filter
40
. Alternatively, the vent valve
96
is closed to isolate the canister
26
from atmospheric air so as to enable performance of an on board diagnostic procedure.
The purge valve
10
is located between the canister
26
and the engine intake manifold
97
of an internal combustion engine
98
. The purge valve
10
may be opened as previously described in relation to
FIG. 1
to place the canister
26
in fluid communication with the intake manifold
97
. Alternatively, the purge valve
10
may be closed as previously described in relation to
FIG. 2
to isolate the canister
26
from the intake manifold
97
. The opening and closing of both the purge valve
10
and the vent valve
96
is controlled by an engine electronic control unit (ECU)
99
.
Under the appropriate conditions, the canister
26
is purged so that fuel vapors collected within the canister
26
do not undesirably escape into the atmosphere. This is done by opening both the purge valve
10
and the vent valve
96
, thus enabling vacuum which is present at the intake manifold
97
to draw in atmospheric air through the canister
26
and then draw out the fuel vapors from the canister
26
. The purged fuel vapors are then used in the normal combustion process. The ECU
99
determines when purging is to occur based on received signals indicative of various engine parameters. Further, the ECU
99
may be programmed to allow purging of the canister
26
at differential rates depending upon the prevailing engine operating conditions. As such, greater amounts of purging may be permitted at certain times while at other times lesser amounts may be allowed.
While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended that the present invention embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.
Claims
- 1. A solenoid for use in a canister purge valve, comprising:a housing having an inlet port and an outlet port; a guide element located in said housing, said guide element including a bobbin section; a valve shaft slidably mounted to said guide element, said valve shaft having a permanent magnet and a valve element wherein said valve element is movable between a closed position wherein said inlet port is closed and an open position wherein said inlet port is opened; a pick coil formed on said bobbin adjacent said magnet, wherein said pick coil generates a first magnetic field having a polarity that is oriented to cause a magnetic attraction with said magnet to move said magnet and thus said valve element to said open position; and a release coil formed on said bobbin adjacent to said magnet, wherein said release coil generates a second magnetic field having a polarity that is oriented to cause said magnet to be repelled to move said magnet and thus said valve element to said closed position.
- 2. The solenoid according to claim 1, wherein a positive voltage is applied to said pick coil to move said valve element to said open position.
- 3. The solenoid according to claim 2 wherein said voltage is approximately 12 volts.
- 4. The solenoid according to claim 1, wherein a positive voltage is applied to said release coil to move said valve element to said closed position.
- 5. The solenoid according to claim 4, wherein said voltage is approximately 12 volts.
- 6. A method for operating a valve, comprising the steps of:providing a housing having a inlet port and an outlet port; providing a valve shaft having a permanent magnet and a valve element, wherein said valve element is movable between a closed position wherein said inlet port is closed and an open position wherein said inlet port is opened; generating a first magnetic field having a polarity that is oriented to cause a magnetic attraction with said magnet to move said magnet and thus said valve element to said open position; and generating a second magnetic field having a polarity that is oriented to cause said magnet to be repelled to move said magnet and thus said valve element to said closed position.
- 7. The method according to claim 6, wherein said step of generating a first magnetic field includes providing a positive voltage to a pick coil.
- 8. The method according to claim 7, wherein said voltage is approximately 12 volts.
- 9. The method according to claim 6, wherein said step of generating a second magnetic field includes providing a positive voltage to a release coil.
- 10. The method according to claim 9, wherein said voltage is approximately 12 volts.
- 11. An evaporative emission control system, wherein said system is in fluid communication with a fuel tank that generates fuel vapors, comprising:a vapor collection canister in fluid communication with said fuel tank for absorbing fuel vapors in said system; a vent valve in fluid communication with said canister for enabling venting of said canister to atmosphere; a leak detection monitor for determining whether there are leaks in said system which are greater than a predetermined level; a canister purge valve for purging said canister, said canister purge valve further comprising: a housing having an inlet port in fluid communication with said canister and an outlet port in fluid communication with an intake manifold of an engine; a guide element located in said housing, said guide element including a bobbin section; a valve shaft slidably mounted to said guide element, said valve shaft having a permanent magnet and a valve element wherein said valve element is movable between a closed position wherein said inlet port is closed and an open position wherein said inlet port is opened; a pick coil formed on said bobbin adjacent said magnet, wherein said pick coil generates a first magnetic field having a polarity that is oriented to cause a magnetic attraction with said magnet to move said magnet and thus said valve element to said open position; a release coil formed on said bobbin adjacent to said magnet, wherein said release coil generates a second magnetic field having a polarity that is oriented to cause said magnet to be repelled to move said magnet and thus said valve element to said closed position; and an electronic engine control unit for controlling opening and closing of said vent valve and said canister purge valve to enable purging of said canister and performance of an on board diagnostic procedure, wherein said engine control unit includes drivers for energizing said pick and release coils.
- 12. The system according to claim 11, wherein a positive voltage is applied to said pick coil to move said valve element to said open position.
- 13. The system according to claim 12 wherein said voltage is approximately 12 volts.
- 14. The system according to claim 11, wherein a positive voltage is applied to said release coil to move said valve element to said closed position.
- 15. The system according to claim 14, wherein said voltage is approximately 12 volts.
- 16. The system according to claim 11 further including bearings for enabling movement of said valve shaft.
- 17. The system according to claim 11 further including a filter in fluid communication with said vent valve.
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A |
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B1 |
6526951 |
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