The entire disclosure of Japanese Patent Application No. 2019-198560 filed Oct. 31, 2019 is expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a pressure gauge.

BACKGROUND ART

A bourdon-tube pressure gauge equipped with a built-in pressure sensor has been known (for instance, Patent Literature 1: JP 2006-510035 A).

A bourdon-tube pressure gauge of Patent Literature 1 includes a battery for driving a pressure sensor, a wireless transmitter, etc. This eliminates the necessity of externally supplying power to the pressure gauge of Patent Literature 1.

However, in the pressure gauge of Patent Literature 1, the above battery is disposed between a movement, which is configured to transfer a displacement of the bourdon tube to a pointer, and a circuit board. In this case, the battery cannot be changed unless a front cover and a dial surface are removed and, further, the movement is removed. Therefore, an operation for battery change is time- and effort-consuming.

SUMMARY OF THE INVENTION

An object of the invention is to provide a pressure gauge configured to facilitate battery replacement.

According to an aspect of the invention, a pressure gauge includes: an introduction member having a fluid introduction hole into which a to-be-measured fluid is introduced; a connection member provided with a fluid flow hole being in communication with the fluid introduction hole; a bourdon tube attached to the connection member to be in communication with the fluid flow hole; a pointer configured to rotate in conjunction with a displacement of a distal end portion of the bourdon tube; a dial plate having a front surface on which a scale to be pointed by the pointer is displayed and having a through hole penetrating from the front surface to a rear surface; a detector configured to detect a pressure of the to-be-measured fluid and attached to the connection member; and an information communication unit in which a circuit board electrically connected to the detector and a battery are installed, the information communication unit including a bottomed cylindrical unit body and a lid covering an opening of the unit body, in which the battery is disposed between the circuit board and the lid, the information communication unit is inserted in the through hole to be disposed astride between the front surface and the rear surface of the dial plate, and the lid is disposed on a side of the unit body close to the front surface of the dial plate.

In the aspect of the invention, the battery is disposed between the lid and the circuit board in the information communication unit. Further, the information communication unit is inserted in the through hole of the dial plate to lie astride between the front surface and the rear surface of the dial plate and the lid is disposed on the side of the unit body close to the front surface of the dial plate. This eliminates the necessity of removing the dial plate, a mechanism for rotating and the pointer, etc. for the battery replacement, so that the battery replacement can be facilitated.

It is preferable that the pressure gauge according to the above aspect further includes a case including a bottomed cylindrical case body and a cover covering an opening of the case body, the case housing therein the connection member, the bourdon tube, the pointer, the dial plate, the detector, and the information communication unit, in which the lid is disposed facing the cover.

In this configuration, it is only necessary to remove the cover from the case body and remove the lid from the unit body in order to replace the battery installed in the information communication unit. Accordingly, the battery replacement can be facilitated.

It is preferable that the pressure gauge according to the above aspect further includes a case including a bottomed cylindrical case body and a cover covering an opening of the case body, the case housing therein the connection member, the bourdon tube, the pointer, the dial plate, the detector, and the information communication unit, in which the cover has a hole at a position corresponding to the information communication unit.

In this configuration, it is only necessary to remove the lid through the hole to replace the battery installed in the information communication unit. Therefore, the battery replacement can be facilitated.

In the pressure gauge according to the above aspect, it is preferable that the information communication unit is disposed in a manner to partially project outside the case through the hole, and the lid is disposed on an external side of the case.

In this configuration, the lid is disposed on an external side of the case, so that it is not necessary to remove the cover from the case body for the battery replacement. Accordingly, the battery replacement can be facilitated.

In the pressure gauge according to the above aspect, it is preferable that the information communication unit further includes an antenna provided at the circuit board, and the antenna is disposed at a position where at least a part of the antenna is not overlaid with the battery as seen from a direction orthogonal to the dial plate.

In this configuration, in sending or receiving an electric wave to or from an external device through the antenna, the battery is not disposed at least at a part of an electric wave transmission path. This allows for restraining interference of the battery with the electric wave to improve a sending/receiving sensitivity of the antenna to the electric wave.

In the pressure gauge according to the above aspect, it is preferable that the connection member includes a step to fit a shape of the unit body.

In this configuration, since the unit body can be housed in the step of the connection member, an inner space of the case can be effectively used. Therefore, the case can be reduced in size.

In the pressure gauge according to the above aspect, it is preferable that the connection member is in a form of a block and has a first attachment side surface disposed along a direction orthogonal to the dial plate and a second attachment side surface disposed along the direction orthogonal to the dial plate and opposite the first attachment side surface, the bourdon tube is attached to the first attachment side surface of the connection member, and the detector is attached to the second attachment side surface of the connection member.

In this configuration, the detector including the sensor element is attached directly to the connection member. Accordingly, since a housing portion or the like for housing the detector is not required, the inner space of the case can be effectively used. In addition, since the detector is attached to the second attachment side surface opposite the first attachment side surface attached to the bourdon tube, a space where the bourdon tube is not disposed within the case can be effectively used. Therefore, the case can be reduced in size.

In the pressure gauge according to the above aspect, it is preferable that the detector includes a sensor element configured to detect the pressure of the to-be-measured fluid and a communication tube through which the sensor element and the fluid flow hole are in communication with each other, the connection member and the communication tube are each made of a metal, and the communication tube and the second attachment side surface are welded to each other.

In this configuration, the communication tube is bonded to the connection member and the sensor element is in communication with the connection member through the communication tube. Accordingly, a bonding point between the communication tube and the connection member can thus be distant from the sensor element, heat of welding for bonding the communication tube to the connection member can be restrained from being transferred to the sensor element. Therefore, an influence of the welding on the sensor element can be reduced.

It is preferable that the pressure gauge of the above aspect further includes a pointer transfer mechanism configured to transfer the displacement of the distal end portion of the bourdon tube to the pointer, and the detector is disposed at a position where the detector does not interfere with the pointer transfer mechanism.

In this configuration, since the detector is disposed at a position where the detector does not interfere with the pointer transfer mechanism, the inner space of the case can be effectively used and the case can be reduced in size.

