JP2014048048A - Microwave densitometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave densitometer which can reduce an amount of microwave leaked to the outside and reduce an error in densitometry of measurement target liquid.SOLUTION: A microwave transmitter and a microwave receiver comprise first fixing members, antennas, second fixing members, penetrating holes, conductive members and connectors, respectively. The first fixing member is fixed to each opening window part in order to touch measurement target liquid. The antenna is shaped in a cylindrical form, comprises a dielectric substrate having a high dielectric constant, and is provided in a manner adjacent to the first fixing member. The second fixing member is provided in order to cover one of bottom faces of the antenna which is opposite to the other bottom face on the side of the first fixing member. The penetrating hole is formed to penetrate the antenna and the second fixing member. The conductive member is provided inside of the penetrating hole. The connector is provided to connect the second fixing member and the conductive member.

Description

  Embodiments described herein relate generally to a microwave densitometer.

  In general, a microwave densitometer includes a microwave transmitter / receiver disposed opposite to each other via a measurement tube through which a liquid to be measured containing a substance to be measured flows or a container for storing the liquid to be measured. Using the above-described microwave transceiver, the difference between the phase delay of the microwave that passes through the liquid to be measured and the phase delay of the microwave that passes through the liquid that does not contain the substance to be measured is calculated to Measure the concentration.

  In such a microwave concentration meter, the dielectric constant of the liquid to be measured changes depending on the temperature and affects the above-described phase difference, that is, an error is caused in the concentration measurement of the liquid to be measured. Liquid temperature correction for correcting the phase difference by measuring the liquid temperature is performed.

  For this reason, as a microwave densitometer, for example, various microwave densitometers such as a microwave densitometer that can reduce errors with a simple configuration even if a sudden change in the liquid temperature occurs have been devised. ing.

JP 2012-26978 A

  However, in the microwave densitometer configured as described above, the ground plane pattern of the antenna portion of the microwave transmitter / receiver is exposed, so that the microwave leaks to the outside and an error occurs in the concentration measurement of the liquid to be measured. There is an inconvenience of causing it.

  The problem to be solved by the present invention is to provide a microwave densitometer capable of reducing the amount of microwave leaking to the outside and reducing errors in the concentration measurement of the liquid to be measured.

  The microwave densitometer of the embodiment is opposed to a measurement tube into which a liquid to be measured containing a substance to be measured flows, a microwave transmitter that transmits a microwave toward the liquid to be measured, and the microwave transmitter. A microwave receiver configured to receive the microwave transmitted from the microwave transmitter, and formed on a tube wall of the measurement tube, to which the microwave transmitter and the microwave receiver can be attached A pair of open windows, and measuring the concentration of the liquid to be measured using a change in the propagation speed of the microwave transmitted from the microwave transmitter.

  Each of the microwave transmitter and the microwave receiver includes a first fixing member, an antenna, a second fixing member, a through hole, a conductive member, and a connector.

  The first fixing member is fixed to each opening window so as to come into contact with the liquid to be measured.

  The antenna has a cylindrical shape, includes a dielectric substrate having a high dielectric constant, and is provided close to the first fixing member.

  The second fixing member is provided so as to cover a bottom surface of the antenna that faces the bottom surface located on the first fixing member side.

  The through hole is formed to penetrate the antenna and the second fixing member.

  The conductive member is provided in the through hole.

  The connector is provided to connect to the second fixing member and the conductive member.

It is a schematic diagram which shows the structural example of the microwave transmitter which comprises the microwave densitometer which concerns on one Embodiment. It is a mimetic diagram showing the 1st modification of a microwave transmitter which constitutes a microwave densitometer concerning the embodiment. It is a mimetic diagram showing the 2nd modification of a microwave transmitter which constitutes a microwave densitometer concerning the embodiment. It is a schematic diagram which shows the 3rd modification of the microwave transmitter which comprises the microwave densitometer which concerns on the same embodiment.

  FIG. 1 is a schematic diagram showing a configuration example of a microwave transmitter constituting a microwave densitometer according to an embodiment. Note that the microwave densitometer usually faces a measurement tube into which a liquid to be measured containing a substance to be measured flows, a microwave transmitter that transmits a microwave toward the liquid to be measured, and a microwave transmitter. A microwave receiver for receiving a microwave transmitted from a microwave transmitter, and a pair of opening windows formed on a tube wall of a measurement tube to which the microwave transmitter and the microwave receiver can be attached And the concentration of the liquid to be measured is measured using a change in the propagation speed of the microwave transmitted from the microwave transmitter.

  Here, for simplification of description, description of a general microwave densitometer is omitted. For details of a general microwave densitometer, refer to JP 2012-26978 A. Below, the microwave transmitter and microwave receiver which mainly comprise a microwave densitometer are demonstrated.

  As shown in FIG. 1, the microwave transmitter 1 constituting the microwave densitometer includes a first fixing member 2, an antenna 3, a second fixing member 4, a third fixing member 5, a through hole 6, and a conductive member 7. And a connector 8. Although FIG. 1 shows an example of the configuration of the microwave transmitter 1, it is noted that the microwave receiver constituting the microwave densitometer has the same configuration as the microwave transmitter 1 shown in FIG. I want.

  The first fixing member 2 is provided in the opening window so as to be in contact with the liquid to be measured, and is usually formed from a synthetic resin member such as plastic. Although the first fixing member 2 is formed from a synthetic resin member in the above description, the first fixing member 2 is not limited to this and may be any member that transmits microwaves transmitted from the antenna 3 described later.

  As shown in FIG. 1, the antenna 3 has a cylindrical shape, includes a dielectric substrate having a high dielectric constant (for example, a dielectric substrate made of ceramic), and is provided close to the first fixing member 2. Is. The antenna 3 is fixed using a second fixing member 4 (for example, a thin metal plate) in order to be provided close to the first fixing member 2. In addition, an antenna pattern (not shown) and a ground plane pattern (not shown) are usually formed on the two bottom surfaces of the antenna 3, respectively. More specifically, a linear antenna pattern for transmitting microwaves is formed on the bottom surface of the antenna 3 located on the first fixing member 2 side, and the other bottom surface is connected to the ground potential. A ground plane pattern is formed.

  The third fixing member 5 is provided so as to cover the bottom surface of the antenna 3 that faces the bottom surface located on the first fixing member 2 side (that is, the bottom surface on which the ground plane pattern is formed). The third fixing member 5 may be any member as long as it does not easily transmit the microwave transmitted from the antenna 3. For example, a member formed from metal can be used.

  The through hole 6 is formed so as to penetrate the antenna 3 and the third fixing member 5, and a conductive member (also referred to as a core wire) 7 is provided in the through hole 6. The core wire 7 is for supplying electricity supplied from an electric circuit (not shown) in the microwave densitometer to the antenna pattern of the antenna 3. In addition, let the diameter of the through-hole 6 be a diameter of an allowable dimension that can provide the core wire 7. The core wire 7 is usually fixed by soldering to the antenna pattern.

  The connector 8 is provided so as to be connected to the third fixing member 5 and the core wire 7. The electrical circuit in the microwave densitometer described above and the microwave transmitter 1 are connected to each other in the microwave transmitter 1. Electricity is supplied to the core wire 7.

  According to the embodiment described above, the configuration in which the microwave transmitter / receiver includes the third fixing member 5 greatly reduces the amount of microwave leaking to the outside, and reduces errors in measuring the concentration of the liquid to be measured. Can be made.

  As a further effect of the configuration in which the microwave transceiver includes the third fixing member 5, there is an effect of preventing the connector 8 from being damaged. Normally, the connector 8 is directly connected to the ground plane pattern formed on the antenna 3 by soldering, so that the connection strength is weak. For example, when the connector 8 is applied with a force of about 1 [N · m], it is easily damaged. There was an inconvenience. However, in the present embodiment, the third fixing member 5 that covers the ground plane pattern formed on the antenna 3 can be provided, so that the connector 8 can be screwed to the third fixing member 5. Compared to the case, the connection strength can be increased, and damage to the connector 8 can be prevented.

  Further, in the present embodiment, it has been described that the third fixing member 5 that covers the ground plane pattern formed on the antenna 3 is provided. However, for example, as illustrated in FIG. 2, the ground plane pattern molded on the antenna 3 is electrically conductive. Alternatively, the adhesive 3 may be applied so that the antenna 3 and the third fixing member 5 are integrally fixed. Thereby, since the ground plane pattern shape | molded by the antenna 3 contacts the 3rd fixing member 5 reliably, grounding is fully made and the leakage of a microwave can be reduced more. When applying the conductive adhesive 9 to the ground plane pattern formed on the antenna 3, it is necessary to apply the conductive adhesive 9 while avoiding the signal line from the connector 8.

  Furthermore, in the present embodiment, it has been described that the antenna 3 is fixed using the second fixing member 4 in order to be provided close to the first fixing member 2, but for example, as shown in FIG. The elastic member 10 may be provided between the antenna 3 and the antenna 3 may be brought close to the first fixing member 2. This can prevent the antenna from being damaged due to vibration or impact. That is, when the second fixing member 4 such as a thin metal plate is used for fixing, if a vibration or impact is applied, a large load is applied to the antenna 3 through the second fixing member 4 and the antenna 3 may be damaged. On the other hand, when the elastic member 10 is used for fixing, even if vibration or impact is applied, the elastic member 10 absorbs vibration or impact, and a large load is not applied to the antenna 3, thereby preventing the antenna 3 from being damaged. be able to.

  Note that the elastic member 10 shown in FIG. 3 may use rubber 11 (for example, an O-ring or the like) as shown in FIG. 4, for example. As a result, the antenna 3 can be prevented from being damaged while having a cheaper structure. A soft synthetic resin member or the like may be used instead of the elastic member 10 and the rubber 11.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Microwave transmitter, 2 ... 1st fixing member, 3 ... Antenna, 4 ... 2nd fixing member, 5 ... 3rd fixing member, 6 ... Through-hole, 7 ... Conductive member, 8 ... Connector, 9 ... Conductive Adhesive, 10 ... elastic member, 11 ... rubber.

Claims (5)

A measuring tube into which a liquid to be measured containing a substance to be measured flows, a microwave transmitter for transmitting a microwave toward the liquid to be measured, and a microwave transmitter provided so as to face the microwave transmitter. A microwave receiver that receives the microwave transmitted from the transmitter, and a pair of opening windows that are formed on the wall of the measurement tube and to which the microwave transmitter and the microwave receiver can be attached, A microwave concentration meter that measures the concentration of the liquid to be measured using a change in propagation speed of microwaves transmitted from the microwave transmitter,
Each of the microwave transmitter and the microwave receiver is
A first fixing member fixed to each opening window so as to come into contact with the liquid to be measured;
A cylindrical antenna comprising a dielectric substrate having a high dielectric constant and provided in the vicinity of the first fixing member;
A second fixing member provided so as to cover a bottom surface facing the bottom surface located on the first fixing member side among the bottom surfaces of the antenna;
A through hole formed to penetrate the antenna and the second fixing member;
A conductive member provided in the through hole;
A microwave densitometer comprising: a connector provided to connect to the second fixing member and the conductive member. The antenna is
2. The microwave densitometer according to claim 1, wherein a conductive adhesive is applied to a bottom surface facing the bottom surface located on the first fixing member side, and is integrally fixed to the second fixing member. The first fixing member is a synthetic resin member;
The microwave densitometer according to claim 1, wherein the second fixing member is a metal member. The microwave transmitter and the microwave receiver are:
The microwave densitometer according to claim 1, further comprising an elastic member provided between the first fixing member and the antenna.   The microwave densitometer according to claim 4, wherein the elastic member is rubber.

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