GB2367623A - Improvements in or relating to position sensing - Google Patents
Improvements in or relating to position sensing Download PDFInfo
- Publication number
- GB2367623A GB2367623A GB0024461A GB0024461A GB2367623A GB 2367623 A GB2367623 A GB 2367623A GB 0024461 A GB0024461 A GB 0024461A GB 0024461 A GB0024461 A GB 0024461A GB 2367623 A GB2367623 A GB 2367623A
- Authority
- GB
- United Kingdom
- Prior art keywords
- coil
- plunger
- inductance
- arrangement
- solenoid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
- G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Magnetically Actuated Valves (AREA)
Abstract
A solenoid arrangement (200) which allows for the position of a plunger (206) to be determined without the requirement of external measuring apparatus. The arrangement (200) comprises a coil (214) to effect movement of the plunger (206) when the coil (214) is energised. A permanent magnet member (212) retains the plunger (206) in one position when the coil (214) is de-energised and a spring (not shown) retains the plunger (206) in another position. The position of the plunger (206) within the coil (214) is determined by measuring the inductance of the coil (214) using an inductance measurement circuit (236) which is connected to the coil (214) via a switching arrangement (230). A driving circuit (226) is also connected for energising the coil (214) via the switching arrangement (230). The inductance measurement circuit (236) may comprise means for applying a rectangular pulse to the coil (214) and measuring the current as it rises. The solenoid may be used in metering applications such as for gas or electricity.
Description
IMPROVEMENTS IN OR RELATING TO POSITION SENSING The present invention relates to improvements in or relating to position sensing, and is more particularly, although not exclusively, concerned with sensing the position of a solenoid plunger in a utility meter.
It is often desired to know the position of a solenoid plunger within its length of travel. This is achieved by providing an external sensing device which detects the position of the plunger, for example, the position of the plunger may be detected using an optical device located external to the solenoid and which determines the position of a shaft connected to the plunger.
However, such arrangements can be complicated and may be relatively expensive. Furthermore, these arrangements are also relatively unreliable.
It is therefore an object of the present invention to provide a position sensing arrangement which is simpler, cheaper and more reliable.
In accordance with one aspect of the present invention, there is provided a solenoid arrangement including a coil, a plunger located within the coil, and energising means for energising the coil to effect movement of the plunger, characterised in that the arrangement further includes an inductance measuring circuit connected to the coil for measuring the inductance thereof and providing an indication of the position of the plunger with respect to the coil, and in that the inductance measuring circuit uses the same connections as the energising means.
The solenoid arrangement in accordance with the present invention has the advantages that there is no need for an external position sensing device, and that a simpler, cheaper and more reliable device is provided.
The arrangement may further include a switching circuit to which both the energising means and the inductance measuring circuit are connected, the switching circuit operating to connect either one of the energising means or the inductance measuring circuit to the coil.
In a preferred embodiment of the present invention, the arrangement further includes means for latching the plunger at either end of its travel within the coil.
In accordance with another aspect of the present invention, there is provided a gas meter including a solenoid arrangement as described above.
In accordance with a further aspect of the present invention, there is provided an electricity meter including a solenoid arrangement as described above.
For a better understanding of the present invention, reference will now be made, by way of example only, to the accompanying drawings, in which:
Figure 1 is a schematic view of a conventional valve arrangement for a gas meter;
Figure 2 is a schematic view of a valve arrangement for a gas meter in accordance with the present invention;
Figure 3 is a graph illustrating the rise of current for a pure inductance; and
Figure 4 is a graph illustrating the rise of current for a solenoid coil incorporating both a series resistance and inductance.
Although the present invention will be described with reference to a solenoid-operated valve for a gas meter, it will readily be appreciated that the present invention can be used in any situation where a ferromagnetic member is positioned within a coil.
In Figure 1, a conventional valve arrangement 100 is shown. Such a valve arrangement 100 is located within a gas meter (not shown) and is surrounded by gas collected in the meter from the mains supply prior to being drawn off by the use of a gas appliance, for example, a gas cooker, hob or boiler.
The valve arrangement 100 comprises a valve member 102 which is attached to one end of a shaft 104. The other end of the shaft 104 is attached to a ferromagnetic plunger 106 which is located within a hollow member 108 mounted within a ferromagnetic framework 110 by means not shown. At one end of the framework 110, an annular permanent magnet element 112 is provided. A coil 114 is wound round the hollow member 108 as is well known. The valve member 102 is reciprocally moved in accordance with energisation of the coil 114 as will be described in more detail later.
It will readily be understood that the shaft 104, plunger 106, hollow member 108, framework 110 and coil 114 comprise a solenoid. The permanent magnet element 112 provides a latching mechanism for retaining the plunger 106 at one end position within the hollow member 108 when the coil 114 has been de-energised.
A spring (not shown for clarity) is also provided in the hollow member 108 around the shaft 104 to bias the plunger 106 towards the end of the hollow member 108 further away from the permanent magnet element 112. This spring provides a latching mechanism for retaining the plunger 106 at the other end position within the hollow member 108 when the coil 114 has been de-energised.
The valve member 102, at one end of it movement, seats on an annular valve seat member 116 which is located around a hole 118 formed in a portion of a pipe 120 through which gas from the mains supply (not shown)
is directed into the body of the gas meter prior to being drawn off by a gas appliance. When the valve member 102 seats against the valve seat member 116, no gas can enter the meter. When the valve member 102 is in the position shown in the Figure, gas enters the meter and can be used by an appliance.
Ends 122,124 of the coil 114 are connected to a driving circuit 126 as shown which provides current to energise the coil 114 and hence impart movement to the plunger 106. The driving circuit 126 is configured such that the coil 114 can be energised in two directions so that the valve member 102 attached to the plunger 106 by means of the shaft 104 can be moved either against the valve seat member 116 to prevent further gas entering the meter or move away from the valve seat member 116 allowing gas to flow through the hole 118 and into the meter. The energisation of the coil 114 takes the form of a pulse which is of sufficient duration to move the plunger 106. As described above, the permanent magnet member 112 retains the plunger 106 against one end of the hollow member 108, and hence the valve member 102 against the valve seat member 116, once the coil 114 has been de-energised.
Similarly, when the coil 114 has been energised to move the plunger 106 away from the permanent magnet member 112, the spring described above retains the plunger 106 against the other end of the hollow member 108, and hence the valve member 102 away from the valve seat member 116, once the coil has been de-energised. This is known as a latching solenoid valve.
The driving circuit 126 includes a power source (not shown), for example, a battery or mains supply, which provides the energy for producing the energising pulses. The driving circuit 126 is preferably provided on a printed circuit board (PCB). For safety reasons, the PCB including the driving circuit 126 is mounted externally of the meter with the ends 122,124
of the coil 114 extending through the meter housing (not shown) in a gas tight fashion.
In Figure 2, a valve arrangement 200 in accordance with the present invention is shown. The valve arrangement 200 is similar to that shown in
Figure 1 in that the valve arrangement 200 comprises a valve member 202 which is attached to one end of a shaft 204. The other end of the shaft 204 is attached to a ferromagnetic plunger 206 which is located within a hollow member 208 mounted within a ferromagnetic framework 210. At one end of the framework 210, an annular permanent magnet element 212 is provided.
A coil 214 is wound round the hollow member 208 as is well known. The valve member 202 is reciprocally moved in accordance with energisation of the coil 214 as described above with reference to Figure 1.
As before, the shaft 204, plunger 206, hollow member 208, framework 210 and coil 214 comprise a solenoid. The permanent magnet element 212 provides a latching mechanism for retaining the plunger 206 at one position within the hollow member 208 when the coil 214 has been deenergised, and a spring (not shown for clarity) as described above retains the plunger 206 at the other end position within the hollow member 208 when the coil 214 has been de-energised after moving the plunger 206 away from the permanent magnet member 212.
An annular valve seat member 216 is located around a hole 218 formed in a portion of a pipe 220 through which gas is directed into the meter.
Operation of the valve member 202 is identical to that of valve member 102 of Figure 1 and will not be described again here.
In accordance with the present invention, ends 222,224 of the coil 214 are connected to a switching arrangement 230. A driving circuit 226
similar to the driving circuit 126 as described above with reference to Figure 1 is connected to the switching arrangement 230 via connections 232,234.
In accordance with the present invention, the position of the plunger 206 within the hollow member 208 is determined in accordance with the inductance of the coil 214. In order to achieve this measurement, an inductance measurement circuit 236 is also connected to the switching arrangement 230 via connections 238,240.
Switching arrangement 230 operates to switch the coil 214 into connection with the driving circuit 226 and the inductance measurement circuit 236. Any suitable switching means can be provided in the arrangement 230.
The inductance measurement circuit 236 may comprise any suitable means for measuring inductance of the coil 214. For example, the inductance measurement circuit 236 may comprise means for applying a rectangular pulse to the coil 214 and means for measuring the current as it decays.
Alternatively, in a preferred embodiment, the rise in current is measured which is more energy efficient. This is shown in Figures 3 and 4.
In Figure 3, a rectangular pulse 300 is applied to the coil 214 and the current therein rises in response to the pulse, the current being shown by line 310 and is substantially linear for a pure inductance, that is, an inductance having no series resistance component. The pulse is initiated at time to and the current in the coil 214 is measured at time t,. This provides an indication of the inductance of the coil 214 and hence the position of the plunger 206 within it.
However, it is more usual to have a series resistance component with the inductance and this is shown in Figure 4. Here, a rectangular pulse 400 is applied to the coil 214 and the current therein rises in response to the pulse as
shown by line 410. As described with reference to Figure 3, the pulse is initiated at time to and the current in the coil 214 is measured at time t, to provide an indication of the inductance of the coil 214 and hence the position of the plunger 206 within it. In this case, as the coil 214 is not purely inductive, the current rise 410 is non-linear.
Other methods of measuring the inductance in the coil 214 include magnetic detection, bridge circuits, resonance circuits, voltage decay, impedance measurement and determining the energy stored in the coil.
By measuring the inductance of the coil 214, it is possible to determine the position of the plunger 206 within the hollow member 208.
In accordance with the present invention, there is no need for an external measuring device and the coil itself is used to provide the required measurement.
In terms of a gas meter as described above, the inductance measurement circuit 236 and the switching arrangement 230 may also be provided on the PCB on which the driving circuit 226 is mounted or incorporated. In this case, the power supply for the driving circuit 226 may also be used for operation of the inductance measurement circuit 236.
Alternatively, the inductance measurement circuit 236 may have its own power supply.
It will be understood that the latching solenoid arrangement described in Figure 2 may be reversed, for example, the permanent magnet member 212 may be located at the other end of the framework 210 with the spring being positioned to provide an opposing force to retain the plunger 206 in either of its two positions once the coil 214 has been de-energised after moving the plunger 206 away from either of its latched positions.
Although the present invention has been described with reference to a latching solenoid valve in a gas meter, it will be appreciated that the solenoid does not need to be a latching solenoid and may be used in other applications.
Claims (7)
- CLAIMS: 1. A solenoid arrangement including a coil, a plunger located within the coil, and energising means for energising the coil to effect movement of the plunger, characterised in that the arrangement further includes an inductance measuring circuit connected to the coil for measuring the inductance thereof and providing an indication of the position of the plunger with respect to the coil, and in that the inductance measuring circuit uses the same connections as the energising means.
- 2. An arrangement according to claim 1, further including a switching circuit to which both the energising means and the inductance measuring circuit are connected, the switching circuit operating to connect either one of the energising means or the inductance measuring circuit to the coil.
- 3. An arrangement according to claim 1 or 2, further including means for latching the plunger at either end of its travel within the coil.
- 4. A gas meter including a solenoid arrangement according to any one of the preceding claims.
- 5. An electricity meter including a solenoid arrangement according to any one of claims 1 to 3.
- 6. A solenoid arrangement substantially as hereinbefore described with reference to Figures 2 to 4 of the accompanying drawings.
- 7. A gas meter substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0024461A GB2367623A (en) | 2000-10-06 | 2000-10-06 | Improvements in or relating to position sensing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0024461A GB2367623A (en) | 2000-10-06 | 2000-10-06 | Improvements in or relating to position sensing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0024461D0 GB0024461D0 (en) | 2000-11-22 |
| GB2367623A true GB2367623A (en) | 2002-04-10 |
Family
ID=9900764
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0024461A Withdrawn GB2367623A (en) | 2000-10-06 | 2000-10-06 | Improvements in or relating to position sensing |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2367623A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019238272A1 (en) * | 2018-06-14 | 2019-12-19 | Eaton Intelligent Power Limited | Differential having armature position detection |
| US11396935B2 (en) | 2017-06-16 | 2022-07-26 | Eaton Intelligent Power Limited | Differential having armature position detection |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2213594A (en) * | 1987-12-09 | 1989-08-16 | Herion Werke Kg | Apparatus for measuring the position of the armature of a coil-and-armature magnetic device |
| EP0353165A1 (en) * | 1988-07-25 | 1990-01-31 | Eastman Kodak Company | Solenoid engagement sensing circuit |
| US5293551A (en) * | 1988-03-18 | 1994-03-08 | Otis Engineering Corporation | Monitor and control circuit for electric surface controlled subsurface valve system |
| JPH1167536A (en) * | 1997-08-13 | 1999-03-09 | Matsushita Electric Works Ltd | Plunger position detector for electromagnetic device |
-
2000
- 2000-10-06 GB GB0024461A patent/GB2367623A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2213594A (en) * | 1987-12-09 | 1989-08-16 | Herion Werke Kg | Apparatus for measuring the position of the armature of a coil-and-armature magnetic device |
| US5293551A (en) * | 1988-03-18 | 1994-03-08 | Otis Engineering Corporation | Monitor and control circuit for electric surface controlled subsurface valve system |
| EP0353165A1 (en) * | 1988-07-25 | 1990-01-31 | Eastman Kodak Company | Solenoid engagement sensing circuit |
| JPH1167536A (en) * | 1997-08-13 | 1999-03-09 | Matsushita Electric Works Ltd | Plunger position detector for electromagnetic device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11396935B2 (en) | 2017-06-16 | 2022-07-26 | Eaton Intelligent Power Limited | Differential having armature position detection |
| WO2019238272A1 (en) * | 2018-06-14 | 2019-12-19 | Eaton Intelligent Power Limited | Differential having armature position detection |
| CN112313480A (en) * | 2018-06-14 | 2021-02-02 | 伊顿智能动力有限公司 | Differential with armature position detection |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0024461D0 (en) | 2000-11-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |