JP6752707B2 - Gas concentration measuring device - Google Patents

Description

The present invention relates to an ultrasonic measuring device, and more particularly to an ultrasonic measuring device having an ultrasonic vibrator.

Ultrasonic measuring devices using ultrasonic vibrators that emit ultrasonic waves and receive the reflected waves are used for various purposes. For example, ultrasonic measuring devices are used for measuring gas concentration and flow rate in the medical field, detecting gas leaks in factory facilities, detecting obstacles when parking an automobile in a parking lot, and the like.

Specifically, a pair of ultrasonic transducers facing each other are arranged in a pipe through which a sample gas used for medical purposes flows, and ultrasonic waves from one ultrasonic transducer are transferred to the other ultrasonic transducer. By receiving at, the oxygen concentration in the sample gas flowing in the pipe is measured (see, for example, Patent Document 1).

In addition, an ultrasonic speaker and an ultrasonic microphone are arranged side by side on the side surface of the housing provided with an opening, and ultrasonic waves are emitted from the ultrasonic speaker to the gas flowing into the housing, and the reflected ultrasonic waves are emitted. Is received by an ultrasonic microphone to detect the gas concentration in the gas (see, for example, Patent Document 2).

Further, the circuit board and the ultrasonic vibrator are attached to the case, the circuit board and the ultrasonic vibrator are integrated to reduce the size, and the circuit board and the ultrasonic vibrator are mounted on the bumper of the vehicle to detect obstacles (for example, patent documents). See 3). In the configuration described in Patent Document 3, a cylindrical ultrasonic vibrator is inserted and attached to the cylindrical portion of the case.

JP-A-2002-214012 JP-A-2007-107903 Japanese Unexamined Patent Publication No. 2006-279567

The ultrasonic measuring apparatus described in Patent Documents 1 to 3 measures the propagation speed (propagation time) of ultrasonic waves emitted from an ultrasonic vibrator, and is in a state of an object based on a change in the propagation speed of ultrasonic waves. Is judging.

As described above, the ultrasonic measuring device is used in various fields, and the ultrasonic vibrator may receive vibration (including impact) from the outside depending on the usage environment. When the ultrasonic vibrator receives vibration from the outside and the position of the ultrasonic vibrator deviates even slightly, the propagation speed of the ultrasonic wave fluctuates, and as a result, the propagation time also fluctuates. That is, when the ultrasonic vibrator receives vibration from the outside, the propagation time of the ultrasonic wave is affected and the accuracy of determining the state of the object is lowered. In particular, when the ultrasonic measuring device is miniaturized, the space for propagating the ultrasonic waves becomes smaller and the propagation time of the ultrasonic waves becomes shorter, so that external vibration greatly affects the measurement of the propagation time.

Therefore, an object of the present invention is to fix the ultrasonic vibrator to the housing so that the fixed position of the ultrasonic vibrator does not shift even if the ultrasonic vibrator receives vibration from the outside.

The gas concentration measuring device of the present invention is a gas concentration measuring device including a cylindrical ultrasonic vibrator and a housing for holding the ultrasonic vibrator, and positions the ultrasonic vibrator on the housing. The fixing portion is provided on the outer peripheral surface of the ultrasonic vibrator, and is provided on the vibrator fitting portion extending in the circumferential direction of the ultrasonic vibrator and the housing. It has a housing fitting portion that fits with the vibrator fitting portion, and the housing reflects ventilation holes that ventilate the inside and outside of the housing and ultrasonic waves emitted from the ultrasonic vibrator. a reflective surface, was closed, the vibrator engaging portion is projections or grooves, wherein the housing fitting portion is a groove or ridge corresponds to the vibrator fitting portion. Desirably, the housing fitting portion is a pair of curved members that sandwich the vibrator fitting portion in the radial direction.

Further, the present invention is a gas concentration measuring device including a cylindrical ultrasonic vibrator and a housing for holding the ultrasonic vibrator, and the ultrasonic vibrator is positioned and fixed to the housing. A fixed portion is provided, and the fixed portion is provided on the outer peripheral surface of the ultrasonic vibrator and extends in the circumferential direction of the ultrasonic vibrator, and is provided on the housing and the vibrator. The housing has a housing fitting portion that fits with the fitting portion, and the housing has a ventilation hole that ventilates the inside and outside of the housing and a reflective surface that reflects ultrasonic waves emitted from the ultrasonic vibrator. The housing fitting portion is a pair of curved members that sandwich the vibrator fitting portion in the radial direction.

Further, it is characterized in that an elastic member that suppresses vibration is provided between the vibrator fitting portion and the housing fitting portion. Further, the vibrator fitting portion is provided at a predetermined distance from the vibration surface of the ultrasonic vibrator in the axial direction of the ultrasonic vibrator.

According to the present invention, even if the ultrasonic vibrator receives vibration from the outside, the displacement of the ultrasonic vibrator is prevented, so that the propagation time of the ultrasonic wave can be accurately measured. Therefore, the gas concentration measuring device can be used even in a place where the ultrasonic vibrator receives vibration, and the range of use of the gas concentration measuring device can be expanded.

It is an exploded perspective view of the ultrasonic measuring apparatus. It is an exploded perspective view of an ultrasonic vibrator, an analog PCB, and an inner chassis. It is a figure explaining the holding structure of an ultrasonic oscillator, (a) shows the schematic plan view of the ultrasonic measuring apparatus, (b) shows the cross-sectional view of AA of (a). It is an enlarged view of the part B of FIG. It is a schematic side view of the ultrasonic oscillator which shows the modification of the ultrasonic measuring apparatus.

The ultrasonic measuring device 1 in the present embodiment is mounted on a vehicle and is used for detecting a gas leak or the like in the vehicle, for example. As shown in FIG. 1, the ultrasonic measuring device 1 includes a box-shaped front case 10 constituting the housing of the ultrasonic measuring device 1, a PCB unit 20 housed in the front case 10, and an opening of the front case 10. It is provided with a rear cover 30 that closes the door.

A pair of side ventilation holes 11 and 11 for ventilating the inside and outside of the front case 10 are provided on the side surface of the front case 10. Lids 12 and 12 for suppressing the ingress of water and the like are attached to the side ventilation holes 11 and 11, respectively. Further, a reflecting surface 13 that reflects ultrasonic waves is formed on the inner surface of the front case 10.

The PCB unit 20 holds an analog PCB (Printed Circuit Board) 21, a pair of ultrasonic vibrators 22 and 23 connected to the analog PCB 21, a digital PCB 24, an analog PCB 21, an ultrasonic vibrator 22, 23, and a digital PCB 24. The inner chassis 25 is provided.

The analog PCB 21 is a circuit board that drives the ultrasonic vibrators 22 and 23 and processes signals from the ultrasonic vibrators 22 and 23.

The ultrasonic vibrators 22 and 23 have a cylindrical shape, and a piezoelectric element and a backing member are incorporated therein. Further, as shown in FIG. 2, connection pins 22a and 23a for supplying voltage and outputting signals to the piezoelectric elements of the ultrasonic oscillators 22 and 23 are provided on one end surfaces of the ultrasonic oscillators 22 and 23. Has been done.

The ultrasonic vibrators 22 and 23 are arranged so as to be inclined so that the tips for emitting ultrasonic waves are close to each other. Ultrasonic waves are emitted from the vibrating surface 26 of one ultrasonic vibrator 22, and the ultrasonic waves reflected by the reflecting surface 13 of the front case 10 are received by the other ultrasonic vibrator 23. The propagation speed (propagation time) of this ultrasonic wave is measured, and the concentration of a gas such as a gas inside the front case 10 is determined based on the change in the propagation speed.

The digital PCB 24 processes the signal from the analog PCB 21 and outputs it to the outside, and also generates a signal and inputs it to the analog PCB 21.

The inner chassis 25 is positioned and fixed to the front case 10. The inner chassis 25 is fixed to the front case 10 to form a part of the housing of the ultrasonic measuring device 1. The inner chassis 25 includes a frame 25a to which the analog PCB 21 is attached from one side and the digital PCB 24 to be attached from the other side, and a holding portion 25b for holding the ultrasonic vibrators 22 and 23.

The rear cover 30 covers the opening of the front case 10 and seals the front case 10. The rear cover 30 is provided with a ventilation hole 31 for introducing a gas inside the front case 10. A cover 32 having a plurality of lattice-shaped openings is attached to the ventilation holes 31.

In this way, in the ultrasonic measuring device 1, the outside air flows into the inside of the front case 10 through the ventilation holes 31 of the rear cover 30. Ultrasonic waves are emitted from the ultrasonic vibrator 22 toward the reflecting surface 13 with respect to the inflowing gas, and the ultrasonic waves reflected by the reflecting surface 13 are received by the ultrasonic vibrator 23. The presence or absence of gas leakage is determined by determining the gas concentration of the inflowing gas based on the propagation time of the ultrasonic waves during this period.

Next, the fixed structures of the ultrasonic vibrators 22 and 23 will be described with reference to FIGS. 1 to 5. FIG. 2 shows a state in which the PCB unit 20 in FIG. 1 is turned upside down. The digital PCB 24 is not shown.

As shown in FIG. 2, the frame 25a of the inner chassis 25 has a shape corresponding to the shape of the analog PCB 21. The frame 25a of the inner chassis 25 is provided with positioning pins 25c and 25c that engage with the positioning holes 21a and 21a of the analog PCB 21. Further, claws 25d and 25d for locking the analog PCB 21 when the analog PCB 21 is attached are also provided. Therefore, when the analog PCB 21 is attached to the frame 25a of the inner chassis 25, it is positioned by the positioning pins 25c and 25c and held by the claws 25d and 25d.

Circuit wirings 21b and 21b to which connection pins 22a and 23a of the ultrasonic vibrators 22 and 23 are electrically connected are provided on both sides of one end of the analog PCB 21. In FIG. 2, the circuit wirings 21b and 21b on the one side are shown, and the circuit wirings on the other side are not visible. Since the connection pins 22a and 23a of the ultrasonic vibrators 22 and 23 have the same configuration, the connection pins 22a of the ultrasonic vibrator 22 will be described below.

Five connecting pins 22a extend from the end face of the ultrasonic vibrator 22, and these five connecting pins 22a are arranged in two rows of three and two. Three connecting pins 22a are arranged in the first row, and two connecting pins 22a are arranged in the second row. The distance between the connection pin 22a in the first row and the connection pin 22a in the second row is set to be substantially the same as the thickness of the analog PCB 21. That is, the analog PCB 21 is sandwiched between the connection pins 22a in the first row and the connection pins 22a in the second row from the front and back surfaces. In this state, by soldering each connection pin 22a to the circuit wiring 21b, the ultrasonic vibrator 22 is electrically connected to and fixed to the analog PCB 21.

Grooves 22b and 23b as vibrator fitting portions are formed on the outer peripheral surfaces of the ultrasonic vibrators 22 and 23 over the entire circumference along the circumferential direction. The grooves 22b and 23b are formed on the peripheral surface behind the piezoelectric elements other than the portion where the piezoelectric elements of the ultrasonic vibrators 22 and 23 are embedded, that is, in the axial direction of the ultrasonic vibrators 22 and 23. .. That is, it is formed on the central portion of the ultrasonic vibrators 22 and 23 or on the peripheral surface on the connection pins 22a and 23a side.

On the other hand, a holding portion 25b is provided on the edge of the frame 25a corresponding to the circuit wirings 21b and 21b. The holding portion 25b has curved surfaces 25e and 25e along the outer peripheral surfaces of the ultrasonic vibrators 22 and 23. The curved surfaces 25e and 25e are provided with a plurality of ribs for improving the rigidity. Further, the curved surfaces 25e and 25e are provided with ridges 25f and 25f as housing fitting portions for positioning the ultrasonic vibrators 22 and 23 and fixing the ultrasonic vibrators 22 and 23. There is.

The ridges 25f and 25f correspond to the grooves 22b and 23b, and the widths of the grooves 22b and 23b are substantially the same as the widths of the ridges 25f and 25f. Therefore, by attaching the ultrasonic vibrators 22 and 23 to the holding portion 25b of the inner chassis 25, the grooves 22b and 23b of the ultrasonic vibrators 22 and 23 and the ridges 25f and 25f of the inner chassis 25 are fitted to each other. By fitting, the ultrasonic vibrators 22 and 23 are positioned and fixed to the holding portion 25b of the inner chassis 25. That is, the ultrasonic vibrators 22 and 23 are positioned in the axial direction as well as in the radial direction. That is, the ridges 25f and 25f and the grooves 22b and 23b form a fixing portion for positioning and fixing the ultrasonic vibrators 22 and 23 to the inner chassis 25.

Further, as shown in FIG. 1, curved surfaces 10a and 10a similar to the curved surfaces 25e and 25e of the inner chassis 25 are formed at positions corresponding to the ultrasonic vibrators 22 and 23 of the front case 10. The curved surfaces 10a and 10a are formed with ribs formed on the curved surfaces 25e and 25e of the inner chassis 25, ribs similar to the ridges 25f and 25f, and ridges 10b and 10b, respectively.

Therefore, the ultrasonic vibrators 22 and 23 are sandwiched and fixed in the vertical direction, that is, in the radial direction by the ridges 25f and 25f of the inner chassis 25 and the ridges 10b and 10b of the front case 10.

In this way, the grooves 22b and 23b are provided on the outer peripheral surfaces of the ultrasonic vibrators 22 and 23, and the ridges 25f and 25f that fit into the grooves 22b and 23b are provided on the inner chassis 25, and the grooves 22b and 23b are provided. By fitting the ridges 25f and 25f together, the ultrasonic vibrators 22 and 23 are positioned and fixed to the inner chassis 25 which is the housing, so that the ultrasonic vibrators 22 and 23 can be positioned with high accuracy. it can. Further, the ultrasonic vibrators 22 and 23 can be firmly fixed to the inner chassis 25 so as not to be displaced.

Further, since the ultrasonic vibrators 22 and 23 are sandwiched and held and fixed by the ridges 25f and 25f of the inner chassis 25 and the ridges 10b and 10b of the front case 10, the ultrasonic vibrators 22 and 23 are further supported. It can be firmly fixed to the housing (inner chassis 25 and front case 10) of the ultrasonic measuring device 1.

Further, the curved surfaces 25e and 25e on which the ridges 25f and 25f of the inner chassis 25 are formed and the curved surfaces 10a and 10a on which the ridges 10b and 10b of the front case 10 are provided are reinforced by ribs. Therefore, the rigidity is high, and the ultrasonic vibrators 22 and 23 can be fixed so as not to be displaced.

Therefore, even if the ultrasonic vibrators 22 and 23 receive vibration from the outside, the displacement of the ultrasonic vibrators 22 and 23 is prevented, so that the propagation time of the ultrasonic waves can be accurately measured. As a result, the ultrasonic measuring device 1 can be used even in a place where the ultrasonic vibrators 22 and 23 are subject to vibration, and the range of use of the ultrasonic measuring device 1 can be expanded.

Further, if the ultrasonic vibrators 22 and 23 are firmly held and fixed at or near the vibration surfaces 26 of the ultrasonic vibrators 22 and 23, the vibration of the vibration surface 26 is hindered. However, in the present embodiment, the grooves 22b and 23b are formed. On the outer peripheral surface of the ultrasonic vibrators 22 and 23, the vibration of the vibrating surface 26 is not hindered even if the vibration surfaces 26 of the ultrasonic vibrators 22 and 23 are firmly held and fixed. Since it is formed at a predetermined distance, it is possible to realize firm fixing of the ultrasonic vibrators 22 and 23 without interfering with the vibration of the vibrating surface 26.

Even if a ridge is formed on the outer peripheral surfaces of the ultrasonic vibrators 22 and 23 and a groove is formed on the curved surfaces 25e and 25e of the inner chassis 25 and the curved surfaces 10a and 10a of the front case 10, the above-mentioned effect can be obtained. A similar effect can be obtained.

Next, a modified example of the holding structure of the ultrasonic vibrators 22 and 23 will be described. As shown in FIG. 5, a cylindrical silicone rubber 40 (elastic member) is mounted on the outer peripheral surface of the ultrasonic vibrator 22. The silicone rubber 40 is in close contact with the groove 22b of the ultrasonic vibrator 22. Further, the silicone rubber 40 having a property of suppressing vibration is used.

Then, the ultrasonic vibrator 22 is fixed to the inner chassis 25 and the front case 10 via the silicone rubber 40. Similarly, the ultrasonic rubber 40 is attached to the ultrasonic vibrator 23 and fixed to the inner chassis 25 and the front case 10.

By fixing the ultrasonic vibrators 22 and 23 via the silicone rubbers 40 and 40 in this way, vibration from the outside is suppressed by the silicone rubbers 40 and 40 and transmitted to the ultrasonic vibrators 22 and 23. Can be reduced. Further, it is possible to reduce the transmission of the vibration of the ultrasonic vibrators 22 and 23 itself to the housing. The silicone rubber 40 may be attached only to the portions of the grooves 22b and 23b.

Although the ultrasonic measuring device 1 in the present embodiment has been described as being mounted on a vehicle, it may be used as a portable measuring device to be carried at a medical site, a factory facility, or the like in addition to such an application. In addition to measuring gas leakage, it may be used for measuring gas temperature, humidity, atmospheric pressure, flow velocity, and gas composition.

1 Ultrasonic measuring device, 10 Front case, 10a curved surface, 10b ridge, 11 side vent, 12 lid, 13 reflective surface, 20 PCB unit, 21 analog PCB, 21a positioning hole, 21b circuit wiring, 22, 23 Ultrasonic transducer, 22a, 23a connection pin, 22b, 23b groove, 24 digital PCB, 25 inner chassis, 25a frame, 25b holding part, 25c positioning pin, 25d claw, 25e curved surface, 25f ridge, 26 vibrating surface, 30 rear cover, 31 vents, 32 covers, 40 silicone rubber.

Claims (5)

A gas concentration measuring device including a cylindrical ultrasonic vibrator and a housing for holding the ultrasonic vibrator.
A fixing portion for positioning and fixing the ultrasonic vibrator to the housing is provided.
The fixed part is
An oscillator fitting portion provided on the outer peripheral surface of the ultrasonic oscillator and extending in the circumferential direction of the ultrasonic oscillator,
A housing fitting portion provided on the housing and fitting with the vibrator fitting portion,
Have,
The housing is
Vents that ventilate the inside and outside of the housing,
A reflective surface that reflects ultrasonic waves emitted from the ultrasonic vibrator,
Have a,
A gas concentration measuring device, wherein the vibrator fitting portion is a ridge or a groove, and the housing fitting portion is a groove or a ridge corresponding to the vibrator fitting portion . In the gas concentration measuring device according to claim 1 ,
The housing fitting portion is a gas concentration measuring device characterized by being a pair of curved members that sandwich the vibrator fitting portion in the radial direction. A gas concentration measuring device including a cylindrical ultrasonic vibrator and a housing for holding the ultrasonic vibrator.
A fixing portion for positioning and fixing the ultrasonic vibrator to the housing is provided.
The fixed part is
An oscillator fitting portion provided on the outer peripheral surface of the ultrasonic oscillator and extending in the circumferential direction of the ultrasonic oscillator,
A housing fitting portion provided on the housing and fitting with the vibrator fitting portion,
Have
The housing is
Vents that ventilate the inside and outside of the housing,
A reflective surface that reflects ultrasonic waves emitted from the ultrasonic vibrator,
Have
The gas concentration measuring device is characterized in that the housing fitting portion is a pair of curved members that sandwich the vibrator fitting portion in the radial direction. The gas concentration measuring device according to any one of claims 1 to 3.
A gas concentration measuring device characterized in that an elastic member that suppresses vibration is provided between the vibrator fitting portion and the housing fitting portion. The gas concentration measuring device according to any one of claims 1 to 4.
The gas concentration measuring device is characterized in that the vibrator fitting portion is provided at a predetermined distance from the vibration surface of the ultrasonic vibrator in the axial direction of the ultrasonic vibrator.

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