JPH06137490A - Sensor unit, monitoring circuit and sensor device containing these unit and circuit - Google Patents
Sensor unit, monitoring circuit and sensor device containing these unit and circuitInfo
- Publication number
- JPH06137490A JPH06137490A JP11076593A JP11076593A JPH06137490A JP H06137490 A JPH06137490 A JP H06137490A JP 11076593 A JP11076593 A JP 11076593A JP 11076593 A JP11076593 A JP 11076593A JP H06137490 A JPH06137490 A JP H06137490A
- Authority
- JP
- Japan
- Prior art keywords
- conductor
- sensor
- sensor unit
- terminal
- temperature sensing
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/243—Schematic arrangements of probes combined with measuring circuits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16T—STEAM TRAPS OR LIKE APPARATUS FOR DRAINING-OFF LIQUIDS FROM ENCLOSURES PREDOMINANTLY CONTAINING GASES OR VAPOURS
- F16T1/00—Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers
- F16T1/38—Component parts; Accessories
- F16T1/48—Monitoring arrangements for inspecting, e.g. flow of steam and steam condensate
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/242—Mounting arrangements for electrodes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/246—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid thermal devices
- G01F23/247—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid thermal devices for discrete levels
- G01F23/248—Constructional details; Mounting of probes
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Examining Or Testing Airtightness (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はセンサユニット、監視回
路及びそれらを含むセンサ装置に関し、特に、センサユ
ニットが凝縮体トラップの作動状態を監視すべく用いら
れてなるものに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor unit, a monitoring circuit and a sensor device including them, and more particularly to a sensor unit used to monitor the operating state of a condensate trap.
【０００２】[0002]
【従来の技術】一般に凝縮体トラップは蒸気機構に使用
されるものであり、このような状況では通常蒸気トラッ
プと呼ばれる。その機能は蒸気を逃さずに凝縮水を蒸気
機構から排出することにある。この機構から蒸気が失わ
れると、エネルギの損失を意味する。従って、蒸気トラ
ップは通常、凝縮水或いは蒸気が近くにあるとそれに反
応する弁を備えており、その弁は凝縮水があれば開弁
し、蒸気があれば閉弁するようになっている。BACKGROUND OF THE INVENTION Condensate traps are commonly used in steam mechanics and, in these circumstances, are commonly referred to as steam traps. Its function is to discharge condensed water from the steam mechanism without letting the steam escape. The loss of steam from this mechanism means a loss of energy. Therefore, steam traps are typically equipped with a valve that reacts with condensed water or steam in the vicinity, which valve opens when condensed water is present and closes when steam is present.
【０００３】しかし、時として蒸気トラップは閉じなか
ったり、或いは部分的にしか閉じることができないこと
があり、この場合、弁が閉じるべき時点を過ぎた後には
蒸気洩れが続くことになる。このような状態を検知する
のは常に容易な訳ではなく、蒸気トラップの誤作動時に
警報信号を発する種々の監視装置が考案されてきた。Occasionally, however, the steam trap may not close, or may only partially close, in which case a steam leak will continue after the time when the valve should close. It is not always easy to detect such a condition, and various monitoring devices have been devised which issue an alarm signal when the steam trap malfunctions.
【０００４】そのような監視装置の１つにセンサ室を備
えたものがあり、そのセンサ室には水が途中まで入って
おり、またセンサ室はその頂部から、正常な水位より低
い位置まで下向きに突出した隔壁により入口部及び出口
部に画成されている。従って、入口及び出口部は水面下
で互いに連通している。また水面上では小さな穴により
入口及び出口部が連通している。One of such monitoring devices is provided with a sensor chamber, which is partially filled with water, and the sensor chamber faces downward from its top to a position lower than the normal water level. A partition wall protruding inward defines the inlet and the outlet. Therefore, the inlet and the outlet are in communication with each other below the water surface. Also, on the water surface, a small hole connects the inlet and outlet.
【０００５】入口及び出口部間の蒸気流は量が少なけれ
ばその穴を通過する。しかし、蒸気流の量が増すと、対
応する圧力差により入口部内の水面が押下げられる。水
面が大きく下がると水位センサにより検知され、蒸気ト
ラップの誤作動を表示する。The vapor flow between the inlet and the outlet passes through the holes if the amount is small. However, as the amount of steam flow increases, the corresponding pressure differential pushes down the water surface in the inlet. When the water level drops significantly, it is detected by the water level sensor and the malfunction of the steam trap is displayed.
【０００６】このように作動する装置の１例が英国特許
出願明細書No.2231407A に開示されている。An example of a device that operates in this way is disclosed in British Patent Application No. 2231407A.
【０００７】弁が浸水すると更に別の問題が生じる可能
性がある。この状態では、弁が開かなかったり、エアロ
ックが生じたり、弁の作動が妨げられたりして、許容し
得ない高さまで凝縮水が溜まってしまう。蒸気トラップ
が浸水すると、センサ室には凝縮水が溜まって水位セン
サが凝縮水の中に沈み、そのセンサは蒸気トラップが正
常に作動していることを示す出力を発する。しかし、凝
縮水の温度が下がるので、かかる浸水を凝縮水の温度及
びその水位を監視することで検知可能とすることが以前
から提案されている。Further problems can arise when a valve is flooded. In this state, the valve does not open, airlock occurs, or the operation of the valve is disturbed, and condensed water accumulates to an unacceptable height. When the steam trap is flooded, condensed water accumulates in the sensor chamber and the water level sensor sinks in the condensed water, and the sensor emits an output indicating that the steam trap is operating normally. However, since the temperature of the condensed water decreases, it has been previously proposed that such infiltration can be detected by monitoring the temperature of the condensed water and its water level.
【０００８】[0008]
【発明が解決しようとする課題】しかし、従来の装置で
は、水位と温度とを感知するために２つの別個のセンサ
が必要となり、装置の構造が複雑で大型化し、コストが
高くつくという問題がある。However, in the conventional device, two separate sensors are required to detect the water level and the temperature, and the structure of the device is complicated and large, and the cost is high. is there.
【０００９】[0009]
【課題を解決するための手段】本発明の第１の特徴によ
れば、絶縁要素を収納する凹部を画成する導電体を備え
たセンサユニットであって、該絶縁要素はその一面から
突出する導電管を支持し、該導電管は温度感知手段を収
納し、該ユニットは更に、温度感知手段の温度と、導電
管及び導電体間の電気的導通状態を表示する信号を受信
すべく、該導電体に対して固定されて導電管及び温度感
知手段に電気的に接続される端子要素を有してなる、セ
ンサユニットが提案される。According to a first aspect of the present invention, there is provided a sensor unit having a conductor defining a recess for accommodating an insulating element, the insulating element protruding from one side thereof. Supporting a conductive tube, the conductive tube housing a temperature sensing means, the unit further for receiving a signal indicative of the temperature of the temperature sensing means and the electrical continuity between the conductive tube and the conductor. A sensor unit is proposed, which comprises a terminal element fixed to a conductor and electrically connected to a conductor tube and a temperature sensing means.
【００１０】導電管及び導電体間の電気的導通状態を監
視することにより、センサ位置における液体の有無を検
知することができる。従って、これら２つの要素は液位
感知手段を構成する。The presence or absence of liquid at the sensor position can be detected by monitoring the electrical continuity between the conductive tube and the conductor. Therefore, these two elements constitute the liquid level sensing means.
【００１１】上記構成において、４つの端子要素を設
け、そのうちの２つを温度感知手段に電気的に接続し、
他の２つを本体及び導電管のそれぞれに電気的に接続し
ても良い。これにより、単一のセンサで凝縮体の温度も
監視することができる。In the above structure, four terminal elements are provided, two of which are electrically connected to the temperature sensing means,
The other two may be electrically connected to the main body and the conductive tube, respectively. This also allows a single sensor to monitor the temperature of the condensate.
【００１２】本発明の更に好適な実施例においては、導
電管と温度感知手段の一方の端子とにそれぞれ電気的に
接続された２つの端子要素が設けられる。この実施例で
は、温度感知手段の他方の端子が導電体に電気的に接続
され、導電体自身が電気コネクタとして作用する。この
ように、導電体は温度感知手段及び液位感知手段の共通
のコネクタを構成する。In a further preferred embodiment of the present invention, two terminal elements are provided, each electrically connected to the conductive tube and one terminal of the temperature sensing means. In this embodiment, the other terminal of the temperature sensing means is electrically connected to the conductor, and the conductor itself acts as an electrical connector. Thus, the conductor constitutes a common connector for the temperature sensing means and the liquid level sensing means.
【００１３】本発明の別の実施例においては、センサの
端子要素は、絶縁要素が導電管及び端子要素の両方を支
持するようにその絶縁要素内に埋設される。In another embodiment of the invention, the terminal element of the sensor is embedded within the insulating element such that the insulating element supports both the conducting tube and the terminal element.
【００１４】本発明の更に別の実施例によれば、センサ
本体は流体室内の流体の状態を感知すべく、ユニットを
流体室に螺着このうにするねじ部を備える。According to yet another embodiment of the present invention, the sensor body includes a threaded portion for screwing the unit into the fluid chamber to sense the condition of the fluid in the fluid chamber.
【００１５】別の実施例では、センサを監視するため
に，温度感知手段の温度を示す抵抗と、導電管及び導電
体間の導通状態を交互に監視する監視回路が、センサと
組合せて設けられる。In another embodiment, in order to monitor the sensor, a resistance indicating the temperature of the temperature sensing means and a monitoring circuit for alternately monitoring the conduction state between the conductive tube and the conductor are provided in combination with the sensor. .
【００１６】公知の蒸気機構は関連する蒸気トラップの
作動状態を示す水位センサを使用している。このような
機構は大規模な２本のワイヤのネットワークにより個々
のセンサに結合された中央制御ステーションを有する場
合がある。この場合、中央制御ステーションから各蒸気
トラップの状態を同時に診断することができる。Known steam schemes use a water level sensor which indicates the operating status of the associated steam trap. Such a mechanism may have a central control station coupled to individual sensors by a large two wire network. In this case, the state of each steam trap can be simultaneously diagnosed from the central control station.
【００１７】しかし、本発明によるセンサユニットは２
つの感知手段を有し、センサの個数を減らしている。従
って、この構成は４本のワイヤのネットワーク、或いは
１つの端子を共用とすれば３本のワイヤのネットワーク
に通常関連するものである。すると、それらを中央で監
視する場合、センサユニットの設置を可能とするため
に、既存の蒸気機構に新たなネットワークを設けなけれ
ばならないという問題が生じる。However, the sensor unit according to the present invention has two
It has one sensing means and reduces the number of sensors. Thus, this configuration is typically associated with a four wire network, or three wire network if one terminal is shared. Then, when monitoring them centrally, there arises a problem that a new network must be provided to the existing steam mechanism in order to enable the installation of the sensor unit.
【００１８】しかしながら、適切なインタフェース回路
を使用することにより、２端子間の監視装置を用いて２
つの感知手段の作動を監視することができる。かかるイ
ンタフェースは逆向き配設された２つのダイオードによ
り、温度感知手段及び液位感知手段を通る電流の流れを
順次制御することで達成され、これら２つのダイオード
は、入力部の信号に依拠して両感知手段の一方或いは他
方からの応答状態を提示する。However, by using a suitable interface circuit, a monitoring device between the two terminals can be used.
The operation of the two sensing means can be monitored. Such an interface is achieved by controlling the flow of current through the temperature sensing means and the liquid level sensing means in sequence by two diodes arranged in opposite directions, these two diodes depending on the signal at the input. The response state from one or the other of both sensing means is presented.
【００１９】従って、本発明のセンサユニットの設置に
際し、大規模な２本の線の電気ネットワークを既に有し
ている蒸気機構を変更する必要はない。Therefore, when installing the sensor unit of the present invention, it is not necessary to modify the steam system which already has a large two-wire electrical network.
【００２０】上記より、本発明の第２の特徴によれば、
２つの可変抵抗の値を監視するための監視回路であっ
て、該回路は２つの端子を備える監視装置と、それらの
端子の電気極性を逆転するための手段よりなり、可変抵
抗は前記端子に並列に接続された前記回路の２本の分岐
線に接続され、各分岐線は対応する抵抗と直列に接続さ
れたダイオードを有し、該ダイオードは、一方の極性の
電圧が前記端子に加えられた時に前記抵抗の一方に電流
が流れ、また反対の極性の電圧が前記端子に加えられた
時に他方の抵抗に電流が流れるように接続されてなる、
監視回路が提案される。From the above, according to the second feature of the present invention,
A monitoring circuit for monitoring the values of two variable resistors, the circuit comprising a monitoring device having two terminals and means for reversing the electrical polarity of those terminals, the variable resistor being connected to said terminals. Connected to two branch lines of the circuit connected in parallel, each branch line having a diode connected in series with a corresponding resistor, the diode having a voltage of one polarity applied to the terminal. When one of the resistors has a current flowing through it, and when a voltage of the opposite polarity is applied to the terminal, the other resistor has a current flowing therethrough.
A monitoring circuit is proposed.
【００２１】[0021]
【実施例】図１及び２の蒸気トラップセンサユニット
は、使用時には、集まった凝縮体の排出を行なう蒸気ト
ラップ（図示せず）の上流に装着される。該センサユニ
ットはアウタケーシングを備え、その内部には流体流路
を形成するセンサ室が画成される。この流体流路は隔壁
５により入口部１及び出口部２に分割される。隔壁５は
センサ室の頂部から下方に延びている。隔壁５の上部領
域にはその両側の圧力を均等化し、弁からの正常な漏洩
レベルの下で、限られた量の蒸気を通過させる穴７が設
けられる。ケーシングには入口部１内に突出したセンサ
３が取付けられる。センサ３は周囲の温度及び凝縮体の
有無に反応する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The steam trap sensor unit of FIGS. 1 and 2 is mounted upstream of a steam trap (not shown) which, in use, discharges condensed condensate. The sensor unit includes an outer casing, and a sensor chamber that defines a fluid flow path is defined therein. This fluid channel is divided into an inlet portion 1 and an outlet portion 2 by a partition wall 5. The partition wall 5 extends downward from the top of the sensor chamber. The upper region of the partition 5 is provided with holes 7 which equalize the pressure on both sides of it and allow a limited amount of vapor to pass under normal leakage levels from the valve. A sensor 3 protruding into the inlet portion 1 is attached to the casing. The sensor 3 is sensitive to ambient temperature and the presence or absence of condensate.
【００２２】図３に示すように、センサ３は円筒状の細
長い金属製の導電体としてのハウジング４を備え、その
一端にセンサ室のアウタケーシングのねじ穴に螺合する
ねじ山が設けられる。ねじ山の部分の直径は典型的には
約１６ミリである。センサ３は温度感知装置８を収納し
た細長い金属製の導電管としての管１０の形態を有する
センサ要素を備えている。センサ３を適所に設置する
と、管１０は流体流路の入口部１内に突出することにな
る。細長い管１０及びハウジング４は共に導電性である
が、金属製のハウジング４内に収納された絶縁要素とし
ての絶縁体１７により互いに離隔されている。絶縁体１
７は、略円筒状のブロックの形態を有し、ハウジング４
に強固に保持されている。管１０は絶縁体１７と同軸に
突出している。管１０の一部は絶縁体１７の一方の周縁
部から突き出ており、管１０の他の部分は絶縁体１７内
に強固に収納されている。管１０とハウジング４との相
対位置は、両者間の抵抗の監視を、公知の水位センサで
使用したものと同じ感知回路で行えるように設定され
る。温度感知装置８を管１０内に収納することにより、
全体的な寸法と熱質量は公知の水位センサのものと略同
じになる。従って、センサ３は、図１及び２に示される
センサユニットのケーシングを交換或いは修正せずに、
公知のセンサと直接交換して使用できる。管１０は直径
が典型的には約３ミリであり、絶縁体１７の上記一方の
周縁部から約１０ミリ突出している。図３に示される実
施例では、センサは端子要素としての４つの端子ピン１
４を更に有し、これらの端子ピン１４はセンサ室の外側
に露出した凹部としてのソケット１６に突出している。
端子ピン１４は、センサ本体に対して固定されて絶縁体
１７の他方の周縁部からソケット１６内に突き出るよう
に絶縁体１７内に埋設される。４つの端子ピンのうち２
つは管１０及びハウジング４にそれぞれ電気的に接続さ
れ、他の２つの端子ピンは温度感知装置８の２つの端子
に接続される。As shown in FIG. 3, the sensor 3 is provided with a cylindrical elongated metal housing 4 as a conductor, and one end thereof is provided with a screw thread to be screwed into a screw hole of an outer casing of the sensor chamber. The diameter of the threaded portion is typically about 16 mm. The sensor 3 comprises a sensor element in the form of a tube 10 as an elongated metal conducting tube housing a temperature sensing device 8. With the sensor 3 in place, the tube 10 will project into the inlet section 1 of the fluid flow path. The elongated tube 10 and the housing 4 are both electrically conductive, but are separated from each other by an insulator 17 as an insulating element housed in the metal housing 4. Insulator 1
7 has the form of a substantially cylindrical block,
It is firmly held in. The tube 10 projects coaxially with the insulator 17. Part of the tube 10 projects from one peripheral edge of the insulator 17, and the other part of the tube 10 is firmly housed in the insulator 17. The relative position of the tube 10 and the housing 4 is set so that the resistance between them can be monitored with the same sensing circuit used in known water level sensors. By housing the temperature sensing device 8 in the tube 10,
The overall dimensions and thermal mass are approximately the same as those of known water level sensors. Therefore, the sensor 3 can be used without replacing or modifying the casing of the sensor unit shown in FIGS.
It can be used by directly replacing the known sensor. The tube 10 is typically about 3 mm in diameter and projects about 10 mm from the one peripheral edge of the insulator 17. In the embodiment shown in FIG. 3, the sensor has four terminal pins 1 as terminal elements.
4 further, these terminal pins 14 project into a socket 16 as a recess exposed outside the sensor chamber.
The terminal pin 14 is fixed to the sensor body and is embedded in the insulator 17 so as to protrude from the other peripheral edge of the insulator 17 into the socket 16. 2 out of 4 terminal pins
One is electrically connected to the tube 10 and the housing 4, respectively, and the other two terminal pins are connected to two terminals of the temperature sensing device 8.
【００２３】しかし、１つの端子を温度感知装置８と管
１０或いはハウジング４との共用とすれば、センサには
３つの端子ピンしか設けなくても良い。更に、この構成
に加えて金属ハウジング４を端子として使用すれば、セ
ンサには２つの端子ピンしか設けなくとも良い。このセ
ンサの実施例は図４に示されており、一方の端子ピンが
金属管１０に接続され、他方の端子ピンは温度感知装置
８の端子の一方に接続されている。温度感知装置８の他
方の端子はそれ自体がコネクタ端子として作用するハウ
ジング４に電気的に接続されている。However, if one terminal is shared by the temperature sensing device 8 and the tube 10 or the housing 4, the sensor may be provided with only three terminal pins. Furthermore, if the metal housing 4 is used as a terminal in addition to this structure, the sensor may be provided with only two terminal pins. An example of this sensor is shown in FIG. 4, with one terminal pin connected to the metal tube 10 and the other terminal pin connected to one of the terminals of the temperature sensing device 8. The other terminal of the temperature sensing device 8 is electrically connected to the housing 4, which itself acts as a connector terminal.
【００２４】センサは図５に示される遠隔幹線動力ユニ
ットに電気的に接続可能である。遠隔ユニットは関し装
置を有しそれぞれ蒸気トラップの作動に対応する。複数
のセンサ３と電気的に接続し得る入力部１８を備える。
こうしてこの機構は複数のセンサを監視して蒸気トラッ
プのうち１つが誤作動した結果生じる浸水状態或いは蒸
気洩れの状態を検出することができる。遠隔ユニットは
どのトラップを監視しているかを示す手段１９を備えて
いる。更に、浸水或いは蒸気洩れのテスト結果を示す複
数のインジケータ２１が設けられる。それらインジケー
タ２１は行ったそれぞれのテストに対する反応が満足す
るものか或いは不満足なものかを示すためにそれぞれ緑
色のダイオード及び赤色のダイオードの形式としても良
い。The sensor is electrically connectable to the remote mains power unit shown in FIG. The remote units have associated devices, each corresponding to the operation of a steam trap. An input unit 18 that can be electrically connected to the plurality of sensors 3 is provided.
The mechanism is thus capable of monitoring a plurality of sensors to detect a flooded or leaked steam condition resulting from the malfunction of one of the steam traps. The remote unit comprises means 19 for indicating which trap is being monitored. In addition, a plurality of indicators 21 are provided to show the results of water immersion or steam leak tests. The indicators 21 may be in the form of green and red diodes, respectively, to indicate whether the response to each test performed is satisfactory or unsatisfactory.
【００２５】既存の蒸気トラップ監視機構では、水位セ
ンサの出力は２本のラインからなるネットワークを介し
て図２のセンサユニットに送られる。水位センサを図３
の本発明によるセンサと取換えてから、従来の配線を利
用するために、各センサの４つの端子ピンを図７に示さ
れる回路により従来の配線の２本の線に接続する。In the existing vapor trap monitoring mechanism, the output of the water level sensor is sent to the sensor unit of FIG. 2 via a network consisting of two lines. Figure 3 shows the water level sensor
In order to utilize the conventional wiring after replacing the sensor according to the present invention, the four terminal pins of each sensor are connected to two wires of the conventional wiring by the circuit shown in FIG.
【００２６】この回路は、可変抵抗ＲＴにより示される
温度感知装置８と、可変抵抗ＲＣ（即ち可変導電性）に
より示される水位センサとを有する。可変抵抗ＲＣは管
１０及びハウジング４間の抵抗である。各可変抵抗に反
対方向に電流を流す２つのダイオードＤ１及びＤ２が互
いに並列に接続された分岐線にそれぞれ逆向きに設けら
れる。両抵抗ＲＴ、ＲＣ及びダイオードＤ１、Ｄ２は監
視回路を構成。回路の入力部２２では、主制御ユニット
により正方向或いは負の方向に電圧Ｖｉｎが加えられ
る。一方向に直流電圧を加えることにより、回路を入力
部２２の＋端子から−端子に向けて流れる電流が発生す
る。従って、１つのダイオードが導通し、電流が２つの
可変抵抗のうち一方を通過する。この抵抗は、例えば電
流測定により測定することができる。回路の入力部で加
えられる電圧を逆向きにすれば、電流は反対方向に流
れ、他方のダイオードが導通する。この場合、電流は他
方の可変抵抗を反対方向に流れる。従って、その場合、
この第２の抵抗も電流測定により測定することができ
る。This circuit comprises a temperature sensing device 8 indicated by a variable resistance RT and a water level sensor indicated by a variable resistance RC (ie variable conductivity). The variable resistance RC is the resistance between the tube 10 and the housing 4. Two diodes D1 and D2 for passing currents in opposite directions to the variable resistors are provided in opposite directions on branch lines connected in parallel with each other. Both resistors RT and RC and diodes D1 and D2 form a monitoring circuit. At the input 22 of the circuit, the voltage Vin is applied in the positive or negative direction by the main control unit. By applying a DC voltage in one direction, a current flowing through the circuit from the + terminal to the − terminal of the input section 22 is generated. Therefore, one diode conducts and the current passes through one of the two variable resistors. This resistance can be measured, for example, by amperometry. If the voltage applied at the input of the circuit is reversed, the current will flow in the opposite direction and the other diode will conduct. In this case, the current flows through the other variable resistor in the opposite direction. Therefore, in that case,
This second resistance can also be measured by amperometry.
【００２７】４つの端子ピンを持つセンサに図７の回路
を使用する場合、電気回路内における端子ピンの接続位
置はコネクタ２６〜２９となる。When the circuit of FIG. 7 is used for a sensor having four terminal pins, the connection positions of the terminal pins in the electric circuit are the connectors 26 to 29.
【００２８】コネクタ２６及び２７は温度感知装置８
（ＲＴ）に接続される２つの端子を示す。コネクタ２８
及び２９は管１０及び金属製ハウジング４に接続される
端子を示す。The connectors 26 and 27 are the temperature sensing device 8
Two terminals connected to (RT) are shown. Connector 28
Reference numerals 29 and 29 denote terminals connected to the tube 10 and the metal housing 4.
【００２９】しかし、端子ピンを２つしか持たないセン
サにこの回路を使用する場合、コネクタ３０が金属製ハ
ウジング４の形態の端子の、両感知手段に対する共通の
コネクタとなり、コネクタ２６及び２８は２つの端子ピ
ンを示す。However, if this circuit is used for a sensor having only two terminal pins, the connector 30 is a common connector for both sensing means of a terminal in the form of a metal housing 4 and the connectors 26 and 28 are two. Shows two terminal pins.
【００３０】本発明によるセンサ監視機構の使用に際し
ては、回路の入力部２２に両方向に電圧を順次加えるこ
とにより、２つの抵抗ＲＣ及びＲＴの測定が順次行われ
る。極性の切換は図５に示される監視ユニットにより自
動的に行われる。これにより、蒸気機構における蒸気ト
ラップの浸水状態、或いはトラップからの蒸気洩れの状
態に関して診断することができる。In using the sensor monitoring mechanism according to the present invention, two resistors RC and RT are sequentially measured by sequentially applying a voltage to the input 22 of the circuit in both directions. The polarity switching is automatically performed by the monitoring unit shown in FIG. As a result, it is possible to diagnose the flooded state of the steam trap in the steam mechanism or the state of steam leakage from the trap.
【００３１】図６は図３のセンサを定期的に監視するた
めの携帯式ユニットを示す。この機構では、携帯式ユニ
ットはセンサ３の４つの端子ピン１４に連結するための
適切なプラグ２３を備えた４本ワイヤリード２０を有す
る。代わりに、この携帯式ユニットをソケットを備えた
２本ワイヤリードを有するものとし、センサ３の４つの
端子ピン１４に接続された図７の回路に接続する構成と
しても良い。FIG. 6 shows a portable unit for periodically monitoring the sensor of FIG. In this arrangement, the portable unit has a four wire lead 20 with suitable plugs 23 for connecting to the four terminal pins 14 of the sensor 3. Alternatively, the portable unit may have two wire leads with a socket and be connected to the circuit of FIG. 7 connected to the four terminal pins 14 of the sensor 3.
【００３２】携帯式ユニットは浸水テスト及び蒸気洩れ
テストをそれぞれ実行する２つのスイッチ２４を備えて
いる。更に、そのテスト結果を表示する発光ダイオード
２５も備えている。図５の遠隔ユニットと同様に、これ
らの発光ダイオードも緑及び赤であり、それぞれ正常な
状態、及び蒸気トラップに故障がある状態を表示する。
携帯式ユニットを使用して、機構の各蒸気トラップを個
別に監視しても良い。The portable unit is equipped with two switches 24 which perform a flood test and a steam leak test, respectively. Further, a light emitting diode 25 for displaying the test result is also provided. Similar to the remote unit of FIG. 5, these light emitting diodes are also green and red, indicating a normal state and a faulty vapor trap, respectively.
A portable unit may be used to monitor each vapor trap of the mechanism individually.
【００３３】図１及び２に示される蒸気トラップセンサ
ユニットを設置する時は、それを蒸気機構のパイプ路の
下方部に装着し、センサ室の入口部１及び出口部２でそ
のパイプ路の流路を画成する。蒸気機構内に生じる凝縮
水はセンサ室を介して排出される。このトラップの正常
な作動状態では、センサ室内の凝縮水の水位はセンサよ
りも高い。蒸気トラップの付近に凝縮水があると、それ
により該トラップが開いて凝縮水の一部を排出する。凝
縮水が排出されると、蒸気トラップは閉じて蒸気の損失
を防止する。蒸気トラップが閉じて正常に作動すると、
管１０が凝縮水に浸り、センサ室内の僅かに高い位置に
蒸気が存在する。従って、このセンサ室内の水温は蒸気
の温度に近くなる。この温度は温度感知装置８により検
知される。更に、凝縮水は管１０及びハウジング４間の
導電路を作る。この状態は従って水位感知手段により検
知される。洩れの量は少なく許容できるものであり、隔
壁に小さな穴７を設けたことにより、かかる少量の洩れ
はセンサ室内の凝縮水の水位に大きな影響を与えない。When installing the steam trap sensor unit shown in FIGS. 1 and 2, it is installed in the lower part of the pipe line of the steam mechanism, and the flow of the pipe line at the inlet 1 and the outlet 2 of the sensor chamber is installed. Define the path. Condensed water generated in the steam mechanism is discharged through the sensor chamber. In the normal operating state of this trap, the level of condensed water in the sensor chamber is higher than that of the sensor. If there is condensed water in the vicinity of the vapor trap, it will open the trap and drain some of the condensed water. Once the condensate is drained, the steam trap closes to prevent steam loss. When the steam trap closes and operates normally,
The tube 10 is submerged in the condensed water and vapor is present slightly higher in the sensor chamber. Therefore, the temperature of water in the sensor chamber becomes close to the temperature of steam. This temperature is detected by the temperature sensing device 8. Further, the condensed water creates a conductive path between the tube 10 and the housing 4. This state is therefore detected by the water level detecting means. The amount of leakage is small and tolerable, and by providing the small hole 7 in the partition wall, such a small amount of leakage does not significantly affect the water level of the condensed water in the sensor chamber.
【００３４】しかし、ひどい洩れが生じた場合、これに
より隔壁５の前後で生じる比較的大きな圧力低下によ
り、穴７を通過できる流れより早い速度で蒸気がセンサ
室を流れる。この圧力低下により、センサ３の領域の凝
縮水の水位は管１０より下方に下がり、蒸気は隔壁５の
下で泡状となる。この状態は抵抗ＲＣの上昇で示され
る。温度感知装置８は蒸気内にあるため、同装置はこの
状態比較的高温を検知する。However, in the case of a severe leak, the relatively large pressure drop occurring before and after the partition wall 5 causes the vapor to flow through the sensor chamber at a faster rate than it can pass through the hole 7. Due to this pressure drop, the water level of the condensed water in the area of the sensor 3 drops below the pipe 10, and the vapor becomes foamy below the partition wall 5. This state is indicated by an increase in resistance RC. Since the temperature sensing device 8 is in steam, it senses the relatively high temperature in this condition.
【００３５】浸水状態では、弁が開いていないか或いは
エアロックが生じている。この場合、センサ室内に凝縮
水が過度に集ることになり、それが時間と共に冷却す
る。この温度変化は温度感知装置８により検知できる。
このように、浸水状態は、管１０が浸水することで水位
感知手段が正常な出力を発しても、検知することができ
る。In the flooded state, the valve is not open or an air lock has occurred. In this case, too much condensed water will collect in the sensor chamber, which will cool over time. This temperature change can be detected by the temperature sensing device 8.
In this way, the flooded state can be detected even if the water level sensing means outputs a normal output due to the flooding of the pipe 10.
【００３６】[0036]
【発明の効果】以上のように本発明によれば、センサユ
ニットは絶縁要素を収納する凹部を画成する導電体を有
し、絶縁要素はその一面から突出する導電管を支持し、
該導電管は温度感知手段を収納し、更に、端子要素が導
電体に対して固定されて導電管に電気的に接続され、温
度感知手段の検知する温度と、導電管及び導電体間の電
気的導通状態を表示する信号を受信する。導電管及び導
電体間の導通により一定値以上の液位を検知することが
でき、従って、単一のセンサで温度及び液位の両方を検
知でき、これによりセンサが凝縮体中に沈んでも凝縮体
トラップの作動状態を正確に監視することができる。As described above, according to the present invention, the sensor unit has the conductor that defines the recess for accommodating the insulating element, and the insulating element supports the conductive tube protruding from one surface thereof.
The conductive tube accommodates the temperature sensing means, and the terminal element is fixed to the conductive body and electrically connected to the conductive tube, and the temperature sensed by the temperature sensing means and the electrical conductivity between the conductive tube and the conductive body are detected. A signal is received to indicate the electrical continuity. It is possible to detect a liquid level above a certain level by the conduction between the conductive tube and the conductor, and therefore, it is possible to detect both the temperature and the liquid level with a single sensor. The operating condition of the body trap can be accurately monitored.
【図１】蒸気トラップセンサユニットの斜視図FIG. 1 is a perspective view of a steam trap sensor unit.
【図２】図１のセンサユニットの概略断面図2 is a schematic cross-sectional view of the sensor unit of FIG.
【図３】図１のセンサユニットのセンサの断面図FIG. 3 is a sectional view of a sensor of the sensor unit shown in FIG.
【図４】図１のセンサユニットのセンサの別の実施例の
断面図4 is a cross-sectional view of another embodiment of the sensor of the sensor unit of FIG.
【図５】センサの信号を読み取る遠隔幹線動力ユニット
の概略図FIG. 5 is a schematic diagram of a remote mains power unit that reads a signal from a sensor.
【図６】センサの信号を読み取る携帯式ユニットの概略
図FIG. 6 is a schematic diagram of a portable unit that reads a signal from a sensor.
【図７】図３のセンサの出力を取り出す電気回路図FIG. 7 is an electric circuit diagram for extracting the output of the sensor of FIG.
１ 入口部 ２ 出口部 ３ センサ ４ ハウジング（導電体） ５ 隔壁 ７ 穴 ８ 温度感知装置 １０ 導電管 １４ 端子ピン １６ 凹部 ２６〜２９ コネクタ Ｄ１、Ｄ２ ダイオード ＲＴ、ＲＣ 抵抗 1 inlet part 2 outlet part 3 sensor 4 housing (conductor) 5 partition wall 7 hole 8 temperature sensing device 10 conductive tube 14 terminal pin 16 recess 26-29 connector D1, D2 diode RT, RC resistance
───────────────────────────────────────────────────── フロントページの続き (72)発明者 アントニー グラハム リケッツ イギリス、ジー エル 52 ６ ティー ワイ グロスターシャ、チェルトナム、エ ルドン ロード、ビーチャースト アベニ ュー 41 ─────────────────────────────────────────────────── ————————————————————————————————————————————————————————————————————————————————— Inventor Antony Graham Ricketts GL 52 6 T.Y. Gloucestershire, Cheltenham, Eldon Road, Beecharst Avenue 41
Claims (8)
体を備えたセンサユニットであって、該絶縁要素はその
一面から突出する導電管を支持し、該導電管は温度感知
手段を収納し、前記ユニットは更に、温度感知手段の温
度と、導電管及び導電体間の電気的導通状態を表示する
信号を受信すべく、前記導電体に対して固定されて導電
管及び温度感知手段に電気的に接続される端子要素を有
してなる、センサユニット。1. A sensor unit comprising a conductor defining a recess for accommodating an insulating element, the insulating element supporting a conductive tube protruding from one surface thereof, the conductive tube accommodating temperature sensing means. However, the unit is further fixed to the conductor to receive the signal indicating the temperature of the temperature sensing means and the electrical continuity between the conductor and the conductor. A sensor unit comprising terminal elements electrically connected.
は前記温度感知手段に電気的に接続され、残る２つは前
記導電体及び導電管にそれぞれ電気的に接続されてな
る、請求項１記載のセンサユニット。2. The terminal element has four, two of which are electrically connected to the temperature sensing means, and the other two are electrically connected to the conductor and the conductive tube, respectively. 1. The sensor unit according to 1.
前記導電管と前記温度感知手段の一方の端子とにそれぞ
れ電気的に接続され、前記温度感知手段の他方の端子は
前記導電体に電気的に接続されてなる、請求項１記載の
センサユニット。3. The terminal element is two, the terminal element is electrically connected to the conductive tube and one terminal of the temperature sensing means, respectively, the other terminal of the temperature sensing means is the conductor. The sensor unit according to claim 1, which is electrically connected to the sensor unit.
感知するために、センサユニットを流体室に螺着するた
めのねじ部を備えてなる、請求項１乃至３のいずれかに
記載のセンサユニット。4. The conductor according to claim 1, further comprising a screw portion for screwing the sensor unit to the fluid chamber in order to sense the state of the fluid in the fluid chamber. Sensor unit.
されてなる、請求項１乃至４のいずれかに記載のセンサ
ユニット。5. The sensor unit according to claim 1, wherein each of the terminal elements is embedded in the insulating element.
サユニットと、前記温度感知手段の温度を示す抵抗、及
び、前記導電管と導電体との間の電気的導通状態を交互
に監視する監視回路との組合せ。6. The sensor unit according to claim 1, a resistance indicating the temperature of the temperature sensing means, and an electrical conduction state between the conductive tube and the conductor are alternately monitored. Combination with the monitoring circuit.
視回路であって、該回路は２つの端子を備える監視装置
と、それらの端子の電気極性を逆転するための手段より
なり、前記可変抵抗は前記端子に並列に接続された前記
回路の２本の分岐線に接続され、各分岐線は対応する抵
抗と直列に接続されたダイオードを有し、該ダイオード
は、一方の極性の電圧が前記端子に加えられた時に前記
抵抗の一方に電流が流れ、また反対の極性の電圧が前記
端子に加えられた時に他方の抵抗に電流が流れるように
接続されてなる、監視回路。7. A monitoring circuit for monitoring the values of two variable resistors, said circuit comprising a monitoring device having two terminals and means for reversing the electrical polarity of those terminals, The variable resistor is connected to two branch lines of the circuit connected in parallel to the terminals, each branch line having a diode connected in series with a corresponding resistor, the diode being a voltage of one polarity. Is connected to the resistor so that a current flows through one of the resistors when the voltage is applied to the terminal, and a current flows through the other resistor when a voltage of the opposite polarity is applied to the terminal.
サユニットと、前記可変抵抗を温度感知手段と、導電体
及び導電管間の抵抗とで構成した請求項７記載の監視回
路とよりなるセンサ装置。8. The monitoring circuit according to claim 7, wherein the sensor unit according to any one of claims 1 to 6, the variable resistance includes a temperature sensing means, and a resistance between a conductor and a conductive tube. Sensor device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9210259:9 | 1992-05-13 | ||
| GB9210259A GB2266956B (en) | 1992-05-13 | 1992-05-13 | Sensor Unit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06137490A true JPH06137490A (en) | 1994-05-17 |
| JP3373891B2 JP3373891B2 (en) | 2003-02-04 |
Family
ID=10715433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11076593A Expired - Fee Related JP3373891B2 (en) | 1992-05-13 | 1993-05-12 | Sensor device and condensate collection trap monitoring mechanism |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3373891B2 (en) |
| DE (1) | DE4313404A1 (en) |
| GB (1) | GB2266956B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20140035910A (en) * | 2011-04-29 | 2014-03-24 | 이턴 코포레이션 | Degradation monitoring system for hose assembly |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2302722B (en) * | 1995-06-29 | 1999-03-31 | Spirax Sarco Ltd | Equipment comprising a condensate trap |
| ES2127122B1 (en) * | 1996-09-02 | 1999-12-16 | Blaquez Navarro Vicente | AUTONOMOUS ELECTRONIC IMPROVED MONITORING SYSTEM FOR PURGERS, VALVES AND INSTALLATIONS IN REAL TIME. |
| ES2120377B1 (en) * | 1996-09-02 | 1999-05-01 | Navarro Vicente Blazquez | AUTONOMOUS ELECTRONIC MONITORING SYSTEM FOR PURGERS, VALVES AND FACILITIES IN REAL TIME. |
| US5992436A (en) * | 1997-07-11 | 1999-11-30 | Armstrong International, Inc. | Monitoring steam traps using RF signaling |
| ES2133240B1 (en) * | 1997-10-03 | 2000-03-16 | Blazquez Navarro Vicente | AUTONOMOUS GLOBAL SYSTEM PERFECTED FOR REMOTE SURVEILLANCE OF BLEEDERS, VALVES AND REAL-TIME FACILITIES. |
| DE19949994A1 (en) * | 1999-10-15 | 2001-04-19 | Claas Saulgau Gmbh | Measurement and storage unit for agricultural equipment service monitoring avoids cabling can be read remotely at suitable intervals. |
| SE0001213D0 (en) | 2000-04-04 | 2000-04-04 | Patrik Melvaas | Sensing device |
| DE10020081A1 (en) * | 2000-04-22 | 2001-10-25 | Bosch Gmbh Robert | Water level sensor for car fuel filters, has self test function through simple time delay circuit |
| DE10053592A1 (en) * | 2000-10-27 | 2002-05-02 | Siemens Ag | Level sensor has two electrode pairs, with effective measurement surfaces extending over part of container height; measurement surfaces of both pairs are formed at least over lower half |
| GB2409116A (en) * | 2003-12-12 | 2005-06-15 | Chao-Wei Huang | Essence burner using resistance detection element to detect water level |
| US7123037B2 (en) * | 2004-02-27 | 2006-10-17 | Wells-Cti, Llc | Integrated circuit temperature sensing device and method |
| FR2901877B1 (en) * | 2006-06-02 | 2016-04-29 | Sc2N Sa | TEMPERATURE SENSOR AND THE LEVEL OF A LIQUID |
| US8050875B2 (en) | 2006-12-26 | 2011-11-01 | Rosemount Inc. | Steam trap monitoring |
| CN101846539B (en) * | 2010-04-09 | 2013-05-15 | 林家彬 | Dual-purpose sensor and electric heating kettle with the same |
| KR20120018104A (en) * | 2011-11-26 | 2012-02-29 | 한용희 | Confirmation apparatus for steam leak |
| US10641412B2 (en) | 2012-09-28 | 2020-05-05 | Rosemount Inc. | Steam trap monitor with diagnostics |
| DE102015011075A1 (en) * | 2015-08-24 | 2017-03-02 | Brandes Gmbh | Water level detector with district heating system |
| US10843429B2 (en) | 2018-05-21 | 2020-11-24 | O2 Partners, Llc | Biodegradable, industrially compostable, and recyclable injection molded microcellular flexible foams |
| JP6947764B2 (en) * | 2019-02-12 | 2021-10-13 | 矢崎総業株式会社 | Liquid level detector unit |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB760838A (en) * | 1954-04-09 | 1956-11-07 | Smith & Sons Ltd S | Improvements in or relating to electric tachometers |
| DE2624009C3 (en) * | 1976-05-28 | 1979-04-19 | A. Ott, Gmbh, 8960 Kempten | Device for measuring the distance of the surface of an electrically conductive medium from an observation point arranged above this surface |
| US4477230A (en) * | 1982-09-30 | 1984-10-16 | Hughes Tool Company | Continuous pressure and temperature readout for submersible pumps |
| US5056363A (en) * | 1990-03-08 | 1991-10-15 | Industrial Engineering And Equipment Company, Inc. | Integral temperature and liquid level sensor and control |
| US5111691A (en) * | 1990-12-20 | 1992-05-12 | Itt Corporation | Conductance/thermal limit control apparatus and method |
-
1992
- 1992-05-13 GB GB9210259A patent/GB2266956B/en not_active Expired - Lifetime
-
1993
- 1993-04-23 DE DE19934313404 patent/DE4313404A1/en not_active Ceased
- 1993-05-12 JP JP11076593A patent/JP3373891B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20140035910A (en) * | 2011-04-29 | 2014-03-24 | 이턴 코포레이션 | Degradation monitoring system for hose assembly |
| JP2014514577A (en) * | 2011-04-29 | 2014-06-19 | イートン コーポレーション | Deterioration monitoring system for hose assemblies |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2266956A (en) | 1993-11-17 |
| DE4313404A1 (en) | 1993-11-18 |
| JP3373891B2 (en) | 2003-02-04 |
| GB9210259D0 (en) | 1992-07-01 |
| GB2266956B (en) | 1995-10-25 |
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