CN1318751A - Resultant jet flow angular-velocity meter - Google Patents

Abstract

The invention belongs to the technical field of sensors. The present invention adopts a synthetic jet flow source composed of a driver vibrating membrane and a nozzle, and one or more pairs of thermosensitive sensors are symmetrically arranged on both sides of the center line of the synthetic jet. double the distance. The present invention is suitable for application in different occasions, especially in harsh working environments. The angular velocity meter has the characteristics of simple structure, good reliability, high sensitivity and resolution, and low cost. And can easily realize large-scale serial production of products. Silicon processing can greatly reduce costs while ensuring good performance.

Description

Synthetic Jet Angular Velocity Meter

The invention belongs to the technical field of sensors.

Angular velocity sensors or gyroscopes are widely used in the fields of automobiles, military, civilian products (such as cameras, toys, mice), industrial control, aviation and ships. It is a goal that people have been pursuing to develop a new type of angular velocity meter device with better performance, higher reliability and lower price. Among the devices used to measure angular velocity at present, a common feature is the need for rotating parts. The existence of rotating parts makes the life of the device short and the reliability low. In addition, it also makes micromachining difficult and expensive. US Patent 5012676 proposes an angular velocity meter with gas jet as the working medium, the schematic diagram of which is shown in Figure 1. It uses a pump 1, 2 to form a fluid flow through the nozzle 3. This fluid flows through a narrow and long channel 5 and is heated by the heating plate 4 to form a hot fluid, and then forms a jet in the cavity 7 through the nozzle 6, and Shoot onto two thermosensitive sensors 8 symmetrically arranged on the centerline of the cavity. When there is no angular velocity, the jet is not deflected, and the two thermosensitive wires detect the same temperature, but when there is an angular velocity, the jet is deflected, and a temperature difference is formed between the two thermal sensors. This difference contains Angular velocity information, angular velocity can be measured by measuring the temperature difference. The key components of the above-mentioned angular velocity meter are the pumps 1, 2 and the flow channel 5. This structure makes the angular velocity meter larger in size and higher in price. In addition, the narrow and long flow channel 5 makes the velocity of the jet decay rapidly, which will greatly reduce the sensitivity and resolution of the angular velocity meter.

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a synthetic jet flow angular velocity meter, which adopts a synthetic jet device as a jet source, adopts a fluid as a working medium, has no rotating parts, and has simple structure, good reliability, The characteristics of high sensitivity and resolution, low cost.

A synthetic jet flow angular velocity meter proposed by the present invention is characterized in that a synthetic jet flow source composed of a driver vibrating membrane and a nozzle is used, and one or more pairs of thermal sensors are symmetrically arranged on both sides of the center line of the synthetic jet. On the other hand, the thermal sensor is located 9-15 times the diameter of the spout.

The present invention can be produced by precision machining or micro-processing technology.

The driver of said synthetic jet can be any one of electromagnetic, piezoelectric, electrostatic and other drive methods.

Said synthetic jet stream source can comprise a casing, the working cavity fixed on the casing, the driver vibrating membrane and the spout, their edges are all fixed on the working cavity, and the measuring tube is fixed on one side of the casing and the cavity. The circuit board of the circuit, a plurality of return flow and cooling holes symmetrically arranged on the jet working cavity.

Working principle and characteristics of the present invention:

First, briefly introduce the concept of synthetic spray. Figure 2 is a schematic diagram of the basic working principle of the synthetic spray. In the figure, there is a cavity 10, one side of the cavity 10 is a film 9, and the other side has a small hole (spout) 11, and the gas periodically enters and flows out of the cavity through the small hole through the periodic vibration of the film. When the gas flows out of the small hole, a shear layer is formed between the outflowing gas and the surrounding static gas, and this layer of vortex will wind up to form a vortex ring 12, which leaves the cavity and moves downstream under the action of self-attraction. At the same time, as the membrane moves back, the gas will be sucked into the cavity from the small hole, and the vortex ring is far away from the cavity at this time, so it is not affected by the suction process. In this way, a series of vortex rings will be formed, and these vortex rings will experience processes such as instability and fragmentation during movement, and finally form turbulent jets 13 near the small holes. This spray has several characteristics: 1) No fluid delivery is required, and the net mass flow rate is zero; 2) Electrical parameter control, the speed of the jet can be adjusted by changing the electrical parameters of the driver. The above characteristics make the synthetic jet can be easily integrated in the measurement of angular velocity, it simplifies the pump device required by the general jet flow, and can be processed by micro-processing technology, thereby greatly reducing the cost.

The schematic diagram of the general principle of measuring angular velocity is shown in Fig. 3. 14 among the figure is an angular velocity meter, F _L is centrifugal force, F _K is Coriolis force, V _r is relative to the velocity in the measuring device of the measured object, and ω is the angular velocity to be measured. It mainly obtains the angular velocity by measuring the Coriolis force information contained in the device.

The synthetic jet angular velocity meter is formed by using the above principles and combining the concept of synthetic jet. Since there is no pump and narrow flow channel, this angular velocity meter can be processed in two ways, one is precision machining, and the other is micro machining, that is, silicon material is processed by IC technology. It uses a synthetic jet to generate a jet as a working medium. In the absence of angular velocity, the jet will not deflect, as shown in Figure 4. At this time, one or more pairs of heated heat-sensitive sensors symmetrically arranged in the jet will receive the same impact from the relatively low-temperature airflow, so the temperature is the same and there will be no electrical signal output. When there is an angular velocity, the jet is deflected due to the Coriolis force, as shown in Figure 5. At this time, the impact of the jet flow on the corresponding pair of thermal sensors is different, and a temperature difference will be generated between the two sensors. This temperature difference is proportional to the Coriolis force, and the Coriolis force contains the information of the angular velocity. , so the angular velocity information can be obtained by measuring the temperature difference.

Features and scope of application of the present invention:

1. Since the synthetic jet device is used as the jet source, the fluid is used as the working medium, and there are no rotating parts, the working life of this angular velocity meter is relatively long.

2. Synthetic spray is used to form a jet, there is no narrow and long flow channel, the structure is simple, and it is easy to process and manufacture;

3. The jet directly acts on the sensitive device, and the jet velocity is relatively high, so the sensitivity and resolution are high.

4. Due to the mature micro-processing technology of synthetic jets and thermal sensors, they can be manufactured in large quantities using the process of manufacturing integrated circuits (IC technology), which greatly reduces the cost, so it is suitable for situations that require low cost, such as airbags in cars security systems and toys;

5. The present invention is suitable for application in different occasions, especially in harsh working environments requiring long life.

Brief description of the drawings:

Fig. 1 is a schematic structural diagram of an existing jet angular velocity meter.

Fig. 2 is a schematic diagram of the working principle of the synthetic spray of the present invention.

Fig. 3 is a schematic diagram of the measurement principle of the angular velocity meter of the present invention.

Fig. 4 is a left-right symmetric view of the jet without angular velocity in the present invention.

Fig. 5 is a diagram showing the deflection of the angular velocity jet in the present invention.

Fig. 6 is a schematic view of the structure of Embodiment 1 using a pair of sensors of the present invention.

Fig. 7 is a schematic structural diagram of Embodiment 2 using two pairs of sensors of the present invention.

The present invention designs two kinds of synthetic jet stream angular velocity meter embodiments, in conjunction with accompanying drawing, describe in detail as follows:

Embodiment 1 is a synthetic jet angular velocity meter with a pair of temperature sensors, the structure of which is shown in FIG. 6 . In the figure, the encapsulation shell 17 can be cylindrical or square, and the fluidic working cavity 19 is fixed on the shell 17, and on one side of the fluidic working cavity is a circuit board 21 with a measuring circuit, which is fixed on the shell 17 and the cavity 19 superior. Arrange synthetic jet on the right side of circuit board 21, it is made of driver vibrating membrane 20 and spout 15, and their edge is all fixed on the working cavity 19. The driver of the vibrating membrane 20 can adopt piezoelectric drive, electrostatic drive or electromagnetic drive, wherein the amplitude of the electromagnetic drive can be relatively large, which is conducive to the formation of high jet velocity. The driver of the vibrating membrane in Embodiment 1 adopts electromagnetic drive, and the working frequency is 500 Hz . The size of the spout 15 can be selected according to needs. Generally speaking, under the condition of the same half-cycle average mass flow rate, the sensitivity and resolution of the angular velocity meter designed with a small-sized spout will be higher than that of a large-sized spout. The diameter of the spout in is 1 mm, and the distance between the vibrating membrane 20 and the spout 15 is 4 mm. In order to detect the jet, two temperature sensors 18a and 18b arranged with the center line of the nozzle 15 as a symmetrical line are fixed on the jet working cavity, and the distance from it to the nozzle is 10 times the diameter of the nozzle in Embodiment 1, that is, the distance from the nozzle 10mm. The temperature sensor is made of a heating thermistor wire whose temperature is higher than that of the jet. In order to effectively form the jet flow and prevent the temperature in the cavity 19 from rising, the four return and cooling holes 16a-16d are symmetrically arranged on the jet working cavity 19, two of which are on the left side of the heating thermistor wire, and two are arranged on the right. In Embodiment 1, the length of the working cavity is 25 mm, the height is 10 mm, and the diameter of the return and heat dissipation holes is 0.5 mm.

The above-mentioned device mainly generates the jet flow through the synthetic jet formed by the driver vibrating membrane 20 and the nozzle 15, and the jet flow will not be deflected in the absence of angular velocity. At this time, a pair of heated heat-sensitive sensors symmetrically arranged in the jet will receive the same impact from the relatively low-temperature airflow, and there will be no electrical signal output due to the same temperature. When there is an angular velocity, the jet is deflected due to the Coriolis force. At this time, the jet impact on a pair of temperature sensors will be different, and the temperature difference will be generated between the two sensors. This temperature difference is proportional to the Coriolis force, and the Coriolis force contains the information of the angular velocity. Therefore, by measuring the temperature The difference can obtain the information of the angular velocity.

Embodiment 2 is a synthetic jet flow angular velocity meter with two pairs of temperature sensors, its structure is shown in Figure 7, the temperature sensors are respectively 18a-18d in the figure, other structures are basically the same as Figure 6, and the working principle is also basically the same, but the detection Higher precision. The length of the working cavity in the second embodiment is 15mm, the height is 6mm, the backflow and heat dissipation aperture is 0.3mm, the driver of the vibrating film is piezoelectric drive, the vibration frequency is 2000Hz, the diameter of the nozzle is 0.5mm, and the distance of the vibrating film is 20mm. The distance between the spout 15 is 1.2 mm, and the distance between the temperature sensor and the spout is 14 times the diameter of the spout, that is, 7 mm.

In addition to the above two embodiments, multiple pairs of sensors can also be arranged symmetrically, which will help improve detection accuracy and reduce errors.

Claims (4)

1. resultant jet flow angular-velocity meter, it is characterized in that, the synthesizing jet source that employing is made of driver vibrating membrane and spout, a pair of or many heat sensitive sensor is arranged symmetrically in the center line both sides of said synthetic spray, the position of this heat sensitive sensor is positioned at nozzle diameter 9-15 doubly outside the distance.

2. resultant jet flow angular-velocity meter as claimed in claim 1 is characterized in that, adopts precision optical machinery processing or micro-processing technology to make.

3. resultant jet flow angular-velocity meter as claimed in claim 1 is characterized in that, the driver of said synthetic spray is an electromagnetism, piezoelectricity, any one of type of drive such as static.

4, resultant jet flow angular-velocity meter as claimed in claim 1, it is characterized in that, said synthesizing jet source comprises a shell, be fixed on the working cavity on the shell, driver vibrating membrane and spout, their edge all on the steady job cavity, is fixed on the wiring board that has metering circuit of shell and cavity one side, is arranged symmetrically in a plurality of backflows and louvre on the jet working cavity.

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