Deflector and design method therefor, and liquid level measurement system and method

Abstract

The present application relates to the technical field of liquid level measurement, and discloses a deflector and a design method therefor, and a liquid level measurement system and method. The deflector comprises a planar reflective surface and a parabolic reflective surface. In the present application, by using technology of combining the planar reflective surface and the parabolic reflective surface, parabolic focusing deflector technology that previously can be used only for vertical tanks is extended to spherical tank, sausage-shaped tanks and other special-shaped tanks, so that main beams of mechanical vibration waves emitted by a probe mounted at any position of a tank body at any angle all become parallel beams, which are vertically emitted upwards to a liquid level inside the tank body without divergence loss, and echoes of the liquid level are focused and reflected to the probe, thereby increasing the intensity of echo signals, achieving the effect of stably and accurately measuring the liquid level of the tank body, and reducing the volume of the deflector.

Description

A steering gear and its design method, a liquid level measurement system and method

[0001] This application claims priority to Chinese Patent Application No. 202411526772.9, filed on October 29, 2024, entitled "A Steering Gear and its Design Method, Liquid Level Measurement System and Method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of liquid level measurement technology, and in particular to a steering device and its design method, a liquid level measurement system and method. Background Technology

[0003] Patent ZL 202210413543.0, "Method, System, Reflector, External Liquid Level Gauge for Vertical Tanks and its Installation Method," discloses a focusing-type external liquid level gauge that uses ultrasound to measure liquid level from the outside of a vertical tank. A probe is installed on the outside of the tank's sidewall to emit an ultrasonic signal into the tank. The ultrasonic wave penetrates the tank's sidewall and enters the liquid inside. It is then reflected by a parabolic focusing deflector and projected parallel to the liquid surface without scattering or attenuation. The reflected signal is then focused back to the focusing deflector, and finally, it penetrates the tank wall and is received by the emitting probe. The liquid level is calculated based on the difference between the transmission and reception times of the ultrasonic signal and the speed of sound in the liquid. The speed of sound is calculated by measuring the known length of a calibrator inside the tank or the diameter of the tank. This focusing diverter method, when applied to vertical tanks, enhances the ultrasonic echo signal by tens of times compared to methods without a parabolic focusing diverter, and also provides stable signal reception. This solves the long-standing problem of weak, intermittent, and unstable echo signals when using external level gauges. However, this focusing diverter technology requires the probe to be mounted on the side wall of the vertical tank; therefore, it is only suitable for vertical tanks and cannot be used on spherical tanks, sausage tanks, or other irregularly shaped tanks. Summary of the Invention

[0004] Based on this, the purpose of this application is to provide a steering device and its design method, a liquid level measurement system and method, which can improve the strength of the echo signal and avoid flickering during the liquid level measurement process of spherical tanks, sausage tanks and other irregularly shaped tanks, thereby improving stability.

[0005] To achieve the above objectives, this application provides the following solution.

[0006] In a first aspect, this application provides a deflector, comprising: a planar reflecting surface and a parabolic reflecting surface; the planar reflecting surface is used to reflect a main beam of mechanical vibration waves to form a primary reflected beam; the parabolic reflecting surface is located on the transmission path of the primary reflected beam and is used to reflect the primary reflected beam to form a secondary reflected beam, the secondary reflected beam being a parallel beam and its direction being vertically upward; wherein, a first preset point T coincides with the focal point of the parabolic reflecting surface at the mirror symmetry point of the planar reflecting surface; the first preset point T is the intersection point of the central axis of the main beam of mechanical vibration waves and the inner wall of the tank to be tested when the main beam passes through the tank; the central axis of the primary reflected beam is located on a horizontal plane; the central axis of the primary reflected beam intersects the planar reflecting surface at a first feature point Δ and intersects the parabolic reflecting surface at a second feature point O; the distance between the first feature point Δ and the second feature point O is less than p, where p is the focal length of the parabolic reflecting surface.

[0007] Secondly, this application provides a liquid level measurement system, including: a measuring probe and the aforementioned diverter; during measurement, the measuring probe is disposed outside the tank to be measured and is used to emit mechanical vibration waves into the tank to be measured; wherein, the main beam of the emitted mechanical vibration wave is the main beam of the mechanical vibration wave; the diverter is disposed inside the tank to be measured, and the planar reflecting surface of the diverter is located in the emission direction of the main beam of the mechanical vibration wave.

[0008] Thirdly, this application provides a liquid level measurement method, which utilizes the aforementioned diverter. The liquid level measurement method includes: setting a measuring probe at a measuring position on the outer wall of the tank to be measured; installing a diverter inside the tank so that the planar reflecting surface of the diverter is located in the emission direction of the measuring probe, and the parabolic reflecting surface is located on the transmission path of the primary reflected beam, and the parabolic reflecting surface is capable of reflecting the primary reflected beam to form a vertically upward secondary reflected beam; wherein, the primary reflected beam is obtained by reflecting the main beam of the mechanical vibration wave from the planar reflecting surface. The emission direction is perpendicular to the tangent plane at the measurement position on the outer wall of the tank under test; a mechanical vibration wave is emitted towards the tank under test using a measuring probe; the main beam of the emitted mechanical vibration wave is the main beam of the mechanical vibration wave; when the main beam of the mechanical vibration wave passes through the tank under test, the intersection of its central axis with the outer wall of the tank under test is the measurement position, and the intersection with the inner wall of the tank under test is the first preset point T; the time when the measuring probe emits the mechanical vibration wave and the time when it receives the liquid surface echo are recorded; wherein, the time when the measuring probe emits the mechanical vibration wave and the time when it receives the liquid surface echo are used to calculate the liquid level of the tank under test.

[0009] Fourthly, this application provides a design method for the aforementioned steering gear, the design method comprising: selecting a measurement position T1 of the tank to be tested, and determining the horizontal inclination angle of the outer wall of the tank to be tested at the measurement position T1 as the horizontal angle β of the emitting end face of the mechanical vibration wave; determining the installation position and installation angle of the planar reflector based on the horizontal angle β; the installation position of the planar reflector is located in the emission direction of the main beam of the mechanical vibration wave; the installation angle of the planar reflector is the angle between the planar reflector and the vertical direction, the value of which is α / 2; where α+β=90°; the installation position is used as the first feature point Δ of the planar reflector; and determining the mirror symmetry point T' of the first preset point T with respect to the planar reflector based on the installation position and installation angle, as the focal point of the parabolic reflector; the first preset point T is... The intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank under test when the main beam passes through the tank under test; wherein, the straight line passing through the mirror symmetry point T', the first feature point Δ, and the second feature point O is a horizontal straight line; the point at a distance p from the focal point along the target direction is determined as the second feature point O; the target direction is the direction from the focal point to the first feature point Δ; the target parabolic surface is determined according to the second feature point O and the focal point; wherein, a portion of the curved surface on the target parabolic surface is used as a parabolic reflector, or the target parabolic surface is used as a parabolic reflector; the size of the planar reflector is determined according to the installation position, installation angle, and detection intensity requirements, and the designed planar reflector is obtained; the size of the parabolic reflector is determined according to the target parabolic surface, and the designed parabolic reflector is obtained.

[0010] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0011] This application provides a diverter and its design method, as well as a liquid level measurement system and method. The diverter of this application includes a planar reflector and a parabolic reflector. This application utilizes a combination of planar and parabolic reflectors to extend the parabolic focusing diverter technology, which was originally only applicable to vertical tanks, to spherical tanks, sausage tanks, and other irregularly shaped tanks. This allows the main beam of the mechanical vibration wave emitted by the probe installed at any position and angle on the tank to be transformed into a parallel beam with no divergence loss, which is then vertically upward and projected onto the liquid surface inside the tank. The echo from the liquid surface is then focused and reflected back to the probe, increasing the intensity of the echo signal. This achieves stable and accurate measurement of the liquid level in the tank, and also reduces the size of the diverter. Specifically, this application utilizes a planar reflector and a parabolic reflector for double reflection, enabling the main beam of the mechanical vibration wave to form a secondary reflected beam that is vertically incident upwards onto the liquid surface inside the tank. That is, in this application, after the main beam is deflected by the diverter, it can be vertically incident onto the liquid surface as a secondary reflected beam (parallel beam). Compared to existing technologies where only one point on the liquid surface is perpendicular to the main beam, the secondary reflected beam obtained in this application is perpendicular to multiple points on the liquid surface. Therefore, it can be perpendicularly reflected back to the diverter by these multiple points, and then reflected again by the parabolic and planar reflectors in the diverter, focusing on a first preset point T. The beam then passes through the tank and is received by the probe. Therefore, using the technical solution of this application, the intensity of the echo signal received by the probe will be higher than in existing methods, thereby improving the intensity of the echo signal, avoiding flickering during water surface fluctuations, and improving stability.

[0012] In this application, the planar reflecting surface, the parabolic reflecting surface, and the mechanical vibration wave also satisfy the following positional relationship: the main beam emitted from the first preset point T (the intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank when it passes through the tank) is incident on the planar reflecting surface (intersecting the planar reflecting surface at the first characteristic point Δ), and after reflection, a primary reflected beam is obtained. The parabolic reflecting surface is located on the transmission path of the primary reflected beam, and the central axis of the primary reflected beam intersects the planar reflecting surface at the first characteristic point Δ and the parabolic reflecting surface at the second characteristic point O. The mirror symmetry point of the first preset point T relative to the planar reflecting surface coincides with the focal point of the parabolic reflecting surface.

[0013] For a parabolic reflector, a single reflected beam is equivalent to being emitted from the mirror symmetry point of the planar reflector, which coincides with the focal point of the parabolic reflector. This is equivalent to emitting a beam directly from the focal point onto the parabolic reflector. Based on the characteristics of a parabola (a mechanical vibration wave passing through the focal point of a parabola can be projected onto the parabola to obtain a parallel beam), a vertically upward parallel beam can be generated.

[0014] In other words, by aligning the mirror's symmetry point with the focal point and properly installing the parabolic reflector, a vertically upward parallel beam can be generated. Furthermore, the first preset point T does not necessarily need to be on the same straight line as the first feature point Δ and the second feature point O. The first preset point T, the first feature point Δ, and the second feature point O can form a triangle. In this triangle, the sum of side TΔ and side ΔO is equal to the focal length p. Since the sum of any two sides of a triangle is greater than the third side, it can be deduced that the length of side TO is less than p. Therefore, the horizontal distance between the first preset point T and the second feature point O is also less than the focal length p.

[0015] The first preset point T can be considered as the emission point of the main beam inside the tank. It should be noted that if the main mechanical wave beam is emitted horizontally from the focal point of the parabolic reflector without using a planar reflecting surface (in this case, the emission point of the main beam inside the tank is the focal point), then the distance between the emission point and the second feature point O is equal to the focal length p. In contrast, the diverter in this application can reduce the horizontal distance between the main beam emission point and the second feature point O on the parabolic surface. That is, using the diverter provided in this application is equivalent to folding the wave transmission path, and the selection of the main beam emission point position can be more flexible.

[0016] Instruction manual illustrations

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 is a schematic diagram of the steering gear provided in an embodiment of this application;

[0019] Figure 2 is a schematic diagram of the principle of measuring the liquid level of a spherical tank by installing a probe on the right side of the manhole of the spherical tank and using a deflector, according to an embodiment of this application.

[0020] Figure 3 is a schematic diagram of the principle of measuring the liquid level of a spherical tank by installing a probe on the left side of the manhole of the spherical tank and using a deflector, according to an embodiment of this application.

[0021] Figure 4 is a schematic diagram illustrating the principle of using a parabolic reflector alone for measuring the liquid level in a spherical tank according to an embodiment of this application;

[0022] Figure 5 is a schematic diagram of the path folding principle provided in the embodiment of this application;

[0023] Figure 6 is a schematic diagram of parabola b during the process of generating a parabolic reflective surface according to an embodiment of this application;

[0024] Figure 7 is a schematic diagram of the principle of proving that the angle between the planar reflecting surface M1 and the vertical coordinate axis TY is α / 2, as provided in the embodiments of this application;

[0025] Figure 8 is a schematic diagram illustrating the principle of the steering gear provided in the embodiment of this application for measuring arbitrary incident angle;

[0026] Figure 9 is a schematic diagram illustrating the principle of using a diverter to measure the liquid level in a vertical tank according to an embodiment of this application;

[0027] Figure 10 is a schematic diagram of the anti-surge groove provided in an embodiment of this application;

[0028] Figure 11 is a schematic diagram of the principle of liquid level measurement using a diverter with a partially reflective surface to reduce volume, as provided in an embodiment of this application.

[0029] Figure 12 is a comparison diagram of the parabolic reflective surface in two cases: the combination of planar reflective surface and parabolic reflective surface provided in the embodiments of this application, and the use of parabolic reflective surface alone.

[0030] Figure 13 is a schematic diagram of determining the planar reflective surface provided in an embodiment of this application;

[0031] Figure 14 is a schematic diagram of determining the parabolic reflective surface according to an embodiment of this application;

[0032] Figure 15 is a schematic diagram of the calibrator's reflective plane and support rod provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The purpose of this application is to provide a steering device and its design method, a liquid level measurement system and method, which can improve the strength of the echo signal and avoid flickering during the liquid level measurement process of spherical tanks, sausage tanks and other irregularly shaped tanks, thereby improving stability.

[0035] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] In one exemplary embodiment, a steering device is provided, as shown in Figure 1, comprising: a planar reflective surface M1 and a parabolic reflective surface M2.

[0037] The aforementioned planar reflecting surface M1 is used to reflect the main beam of the mechanical vibration wave, forming a primary reflected beam. When the main beam of the mechanical vibration wave passes through the tank, the intersection of its central axis and the inner wall of the tank under test can be called the first preset point T. Referring again to Figure 1, if the primary reflected beam is extended in the opposite direction, it can intersect at a point T', which can be called the mirror symmetry point of the first preset point T with respect to the planar reflecting surface M1. The primary reflected beam is equivalent to emanating from the mirror symmetry point.

[0038] The parabolic reflector M2 is located on the transmission path of the primary reflected beam. The mirror symmetry point T' coincides with the focal point of the parabolic reflector M2. The parabolic reflector M2 is used to reflect the primary reflected beam to form a secondary reflected beam. The secondary reflected beam is a parallel beam, and its direction is vertically upward.

[0039] In practice, a planar reflector with any edge shape can be used to form a primary reflected beam, as long as the planar reflector has a planar reflecting surface M1. For example, a reflector plate with a planar reflecting surface can be used as the planar reflector.

[0040] Similarly, a parabolic reflector with any edge shape can be used to form a secondary reflected beam, as long as the parabolic reflector has a parabolic reflective surface M2. For example, a parabolic panel with a parabolic reflective surface can be used to form a secondary reflected beam.

[0041] The principle by which the diverter in this application can produce a vertically upward secondary reflected beam is as follows:

[0042] The parabolic reflecting surface M2 (referred to as the parabolic surface) is obtained by rotating a parabolic segment (one segment of the parabola) around its axis of symmetry (i.e., the axis of symmetry of the parabola). According to the mathematical properties of a parabola, light rays passing through its focus (rays incident on the parabola from its focus) can be reflected by the parabola into parallel rays (rays parallel to the axis of symmetry). This also applies to mechanical vibration waves. The focus of the parabola can be used as the focus of the parabolic surface. Therefore, mechanical vibration waves passing through the focus of the parabola and projected onto the parabolic surface will produce parallel mechanical vibration waves. Furthermore, if the parabolic surface is mounted with the aforementioned axis of symmetry vertical and the opening of the parabola corresponding to the surface facing upwards, the resulting parallel rays will be vertically parallel rays.

[0043] At the same time, the mirror symmetry point T' coincides with the focal point of the parabolic reflecting surface M2, which is equivalent to directly emitting mechanical vibration waves from the focal point to the parabolic reflecting surface. According to the aforementioned characteristics of the parabola, a vertically upward parallel mechanical vibration wave beam can be generated.

[0044] The planar reflecting surface M1 and the parabolic reflecting surface M2 also satisfy the following description:

[0045] The central axis m2 of the primary reflected beam reflected by the planar reflector M1 is located on a horizontal plane; the central axis m2 intersects the planar reflector M1 at a first characteristic point Δ and intersects the parabolic reflector M2 at a second characteristic point O; and the distance between the first characteristic point Δ and the second characteristic point O is less than p, where p is the focal length of the parabolic reflector M2.

[0046] It should be noted that the distance between the mirror-symmetric point T' and the second feature point O is the focal length p. If the distance between the first feature point Δ and the mirror-symmetric point T' is denoted by q, then the distance between the first feature point Δ and the second feature point O can be expressed as pq, which is less than p. Since the mirror-symmetric point T' coincides with the focal point, point T' and the first preset point T are mirror-symmetrically distributed with respect to the plane reflecting surface. Therefore, the distance between the first preset point T and the first feature point Δ is also equal to q.

[0047] The diverter in this embodiment can be applied to liquid level measurement in spherical tanks, vertical tanks, and other irregularly shaped tanks. The following embodiment will use a spherical tank as an example for illustration.

[0048] In other embodiments of this application, the planar reflecting surface M1 in all the above embodiments can reflect all or part of the main beam of mechanical vibration wave, and the parabolic reflecting surface M2 can reflect all or part of the primary reflection beam.

[0049] Taking total reflection as an example, the aforementioned diverter can control the entire energy of the main beam of the mechanical vibration wave to be transmitted parallel to the liquid surface without divergence, and to receive the focused reflected echo. In the following description, ultrasonic waves are used as an example; however, the technical solution of this application is not limited to ultrasonic waves, and can also be sound waves, infrasound, shock waves, etc. The medium through which the mechanical vibration wave is transmitted can be various substances such as solids, liquids, supersaturated vapors, gases, and plasmas. The temperature of the medium through which the mechanical vibration wave is transmitted can range from extremely low temperatures close to absolute zero to hundreds of millions of degrees Celsius in thermonuclear fusion media; there are no limitations on the temperature or pressure of the medium. The condition for the diverter in this embodiment is that the dimensions of the planar reflective surface and the parabolic reflective surface need to be larger than the wavelength of the mechanical vibration wave in the working medium to avoid diffraction and to enable the formation of the main beam.

[0050] The working principle of the steering system is explained below:

[0051] When the planar reflecting surface is used to completely reflect the main beam of the mechanical vibration wave, the diverter can utilize the full energy of the main beam of the mechanical vibration wave when measuring the liquid level in the tank. The ultrasonic main beam emitted by the probe with a divergence angle of 2θ0 (θ0 is the half-emission angle in Figure 1 of this application) is reflected by the planar reflecting surface M1 and then strikes each point of the parabolic reflecting surface M2. The area S of the ultrasonic signal reflected by the parabolic reflecting surface M2 and then projected parallel onto the liquid surface is equal to the top view area of ​​the parabolic reflecting surface M2.

[0052] When there is no liquid entering or leaving the tank, the liquid surface is a stationary horizontal plane, as shown in Figure 5(b). All ultrasonic waves perpendicularly directed towards points S on the liquid surface are reflected vertically downwards back to the parabolic reflector M2. The reflected waves are then focused and reflected by the parabolic reflector M2 towards the planar reflector M1, and then reflected again by the planar reflector M1, continuing along the focusing direction towards point T. Finally, the ultrasonic waves penetrate the tank wall and reach the probe, where they are received. This achieves the goal of focusing and reflecting all the divergent ultrasonic main beam signals emitted by the probe back to the probe.

[0053] When liquid enters or exits the tank, the liquid surface fluctuates, creating peaks and troughs, as shown in Figure 5(a). Ultrasonic waves incident on a peak or trough can be reflected perpendicularly back to the parabolic reflector M2. Due to the use of the deflector in this application, the mechanical vibration wave perpendicular to the liquid surface is no longer a single point, but covers a certain area of ​​the liquid surface, with an area of ​​S. It is assumed that within the covered liquid surface, even with fluctuations, there are multiple peaks and troughs simultaneously within the aforementioned area at any given time, although their positions are variable. However, within the covered liquid surface area, ultrasonic waves incident perpendicularly to the liquid surface can be reflected by multiple peaks and troughs back to the parabolic reflector M2, then focused by the parabolic reflector M2 and directed towards the planar reflector M1, where they are reflected again and superimposed along the focusing direction to point T.

[0054] Assuming there are n random peaks and troughs within the covered liquid surface, n can be calculated using the formula: n = S / λ 2 Where λ is the wavelength of the measured liquid surface fluctuation, and S is the top-view area of ​​the reflecting surface. Compared with existing technologies, the probe can receive the superposition of n signals from the n wave crests and troughs reflected from different positions on the fluctuating liquid surface at any time, thus enhancing the signal sound pressure by n times.

[0055] It should be noted that if the focal length p of the parabolic reflecting surface increases by a factor of k, then the top view area S of the reflecting surface increases by k. 2 The number of wave crests and troughs on the undulating liquid surface reflecting ultrasonic signals increases by a factor of k. 2 The multiple by which the ultrasonic sound pressure level focused on the probe increases, n increases by k. 2 times.

[0056] The relationship between S and p is derived as follows:

[0057] Taking total reflection as an example, the minimum radius R of the vertical cross-section circle of the cone of the first reflected beam at the characteristic point (i.e., the second characteristic point O) of the parabolic reflecting surface M2 is... O = p × tan(θ0), the area of ​​the smallest circle in the top view of the region where the first reflected wave beam is projected onto the parabolic reflecting surface M2 is approximately: Therefore, it can be deduced that S is directly proportional to the square of the focal length p. If the focal length p increases by a factor of k, the top-view area of ​​the parabolic reflecting surface M2 increases by k. 2 times.

[0058] To illustrate the effects of the above technology, the following two sets of experiments were conducted using the aforementioned steering mechanism under conditions of liquid surface fluctuation.

[0059] After the material is fed into the tank, in a set of experiments, when the liquid level in the spherical tank is 3.1 meters, the amplitudes of the liquid level echo signal based on the steering device of this application and the liquid level echo signal without the steering device are 100 millivolts and 4 millivolts, respectively. The amplitude of the echo signal using the steering device of this application is 100 millivolts / 4 millivolts = 25 times that of the echo signal without the steering device.

[0060] In another set of experiments, when the liquid level in the spherical tank was 1.9 meters, the amplitudes of the liquid level echo signal based on the steering device of this application and the liquid level echo signal without the steering device were 75 millivolts and 3 millivolts, respectively. The amplitude of the liquid level echo signal using the steering device of this application was 75 / 3 = 25 times that of the liquid level echo signal without the steering device.

[0061] To illustrate the effects of the above technology, the following experiment was conducted using the aforementioned steering mechanism when the liquid surface was stationary.

[0062] After the material was fed into the tank, in this group of experiments, when the liquid level in the sausage tank was 1.2 meters, the amplitudes of the liquid level echo signal based on the steering device of this application and the liquid level echo signal without the steering device were 11,000 millivolts and 150 millivolts, respectively. The amplitude of the liquid level echo signal using the steering device of this application was approximately 73 times that of the liquid level echo signal without the steering device (11,000 / 150).

[0063] Experiments show that the sound pressure of the echo received by the probe from the liquid surface increases by 73 times when the liquid surface is still, and by 25 times when the liquid surface is fluctuating. Sound pressure P is the sound pressure per unit area, and sound intensity I is the sound energy passing through a unit area per unit time. The relationship between sound intensity I and sound pressure P is I = 1 / 2P. 2 / Z, meaning the sound intensity is proportional to the square of the sound pressure, where Z is the acoustic impedance. The sound pressure increased by 25-73 times, and the sound intensity, or sound energy, increased by 600-5000 times. This significant improvement is attributed to the diverter (hereinafter referred to as the combined diverter) in this application, which incorporates both planar and parabolic reflective surfaces. This diverter transmits the main beam of the mechanical vibration wave emitted by the probe in parallel, without scattering loss, to the liquid surface. This allows for the measurement of many high-viscosity liquids and liquids containing bubbles that previously could not be measured due to high ultrasonic transmission loss. For example, petroleum, due to its high viscosity, suffers significant ultrasonic loss and could not previously be measured using external level gauges; now, it can be measured using the focusing diverter. Another example is liquid ammonia tanks. Because liquid ammonia gas is pumped from the tank into a tanker truck, and the liquid ammonia from the tanker truck is then forced into the tank, a large number of bubbles are generated in the tank during the liquid inflow. These bubbles block the ultrasonic waves used for level measurement, resulting in no echo signal and rendering the external level gauge inoperable. With the addition of a combined diverter, the ultrasonic propagation paths increase, virtually eliminating the possibility of no echo signal. The stronger the obtained liquid surface echo, the more types of liquids can be measured and the more complex operating conditions can be applied.

[0064] The combined steering system in this application, when used in a spherical tank, also has the following advantages compared to using a parabolic reflector alone:

[0065] The approximate area of ​​the parabolic reflector in a top view is: The area S is proportional to the square of the focal length p.

[0066] As shown in Figure 4(a) and (b), Figure 4(a) is a schematic diagram of the principle of using a parabolic reflector alone for measuring the liquid level in a spherical tank, and Figure 4(b) is a partial enlarged view of (a). If only the parabolic reflector is used and the planar reflector is not used, the focal length p of the parabolic reflector will be very small. For example, when the focal length p1 = 30 mm:

[0067] The radius of the top view of the parabolic reflector is R1 = p1 × tan(θ0) = 5.56 mm. Square centimeters.

[0068] When using a combined steering system, the focal length of the parabolic reflector can be very large, for example, when the focal length p2 = 1000 mm:

[0069] The radius of the parabolic reflector in the top view is R2 = p2 × tan(θ0) = 185.34 mm. The area of ​​the parabolic reflector in the top view is... Square decimeters.

[0070] Comparing the focal lengths p1 = 30 mm and p2 = 1000 mm, the ratio of the top-view areas of the parabolic reflecting surface is S1 / S2 = (p1 / p2). 2= (30 mm / 1000 mm) 2 =0.09%, the liquid surface echo signal received by the combined steering probe of this application is reduced by 1000 times when only the parabolic reflector is used.

[0071] When using a parabolic reflector alone, increasing the focal length p will result in an excessively long parabolic deflector.

[0072] As shown in Figure 11, when using a parabolic reflector alone, the focal point of the parabolic reflector is located on the inner wall of the bottom of the spherical tank directly opposite the probe, at a very low position. The emission angle of the ultrasonic wave emitted by the probe is generally between -30 degrees and +30 degrees. In this case, the ultrasonic wave is equivalent to starting from the focal point and obliquely projecting (with a large angle to the horizontal) towards a very high part of the parabolic surface. As a result, the high end of the parabolic reflector device will be more than 2 meters high. This will make the upper part of the parabolic surface very high, which will significantly increase the cost of processing molds. Moreover, in order to reduce the measurement blind zone, the probe is located at a very low position at the bottom of the spherical tank, and the emission angle α of the ultrasonic wave emitted by the probe is very large. The main ultrasonic beam is projected onto a very small area of ​​the upper part of the parabolic surface, so the area S of its top view is very small. That is, the area S of the ultrasonic wave projected from the parabolic reflector onto the liquid surface is very small, and the increase factor n of the sound pressure superimposed on the probe is very small.

[0073] The planar reflective surface and parabolic reflective surface proposed in the above embodiments of this application are combined and folded in an all-directional manner, and designed into a suitable style to reduce the volume according to the shape of the container.

[0074] The embodiments described above in this application employ a planar reflecting surface. As shown in Figures 2-3, the mechanical vibration wave emanating from point T is equivalent to one emanating from the mirror-symmetric point T'. Since the mirror-symmetric point T' coincides with the focal point of the parabolic reflecting surface, compared to using a parabolic reflecting surface alone, the focal point position is raised. Furthermore, the mechanical vibration wave emanating from the focal point can be projected horizontally towards the parabolic reflecting surface, rather than from a very low position towards a very high part of the parabola. Referring to Figure 12, it is clearly visible that, with the same divergence angle, the parabolic reflecting surface M2 of the combined steering gear of this application has a significantly lower upper end and a significantly smaller size compared to a standalone parabolic reflecting surface M2. When the focal length of the parabolic reflecting surface of the combined steering gear is 1000 mm, the highest point of the parabolic reflecting surface is less than 500 mm, which is within a suitable range for use.

[0075] As shown in Figure 1, this embodiment of the application sets up a full acoustic energy combined reflection diverter that vertically projects all the acoustic energy of the main ultrasonic beam emitted by the probe onto the liquid surface based on a planar reflector and a parabolic reflector. This achieves the installation of a large-area parabolic reflector in a very small space with very low processing mold costs, resulting in a large increase in sound pressure by a factor n.

[0076] The combined diverter in this embodiment solves the problem that when measuring the liquid level of a spherical tank with an external level gauge, the liquid surface echo signal received by the probe is weak when static, flickering when fluctuating, intermittent, weak, and unstable. It also solves the problem that when only a parabolic focusing diverter is used, the area of ​​the ultrasonic wave projected onto the liquid surface is very small and the echo is very weak. Moreover, the parabolic reflector is very high, which makes it extremely difficult and expensive to manufacture molds for large-scale precision curved reflectors.

[0077] In an exemplary embodiment, a liquid level measurement system is provided for measuring the liquid level inside a spherical tank from the outside using ultrasound. As shown in Figure 1, it includes, exemplarily, a measuring probe and the aforementioned diverter. During measurement, the measuring probe (hereinafter referred to as the probe) can be placed outside the tank to be measured and is used to emit mechanical vibration waves into the tank. The main beam of the emitted mechanical vibration waves is the aforementioned main beam of mechanical vibration waves. The diverter is placed inside the tank to be measured; for a related description, please refer to the foregoing introduction, which will not be repeated here.

[0078] In other embodiments of this application, the above-mentioned liquid level measurement system may further include: an external liquid level gauge host. The external liquid level gauge host is connected to the above-mentioned measuring probe. The liquid surface echo signal obtained after passing through the deflector can penetrate the tank wall and reach point T1 on the outer wall of the tank. The echo signal is received by the probe and converted into an electrical signal, which is then transmitted to the external liquid level gauge host. The external liquid level gauge host calculates the liquid level height h inside the tank based on the time difference t2-t1 between the time t1 when the mechanical vibration wave is emitted to the probe and the time t2 when the liquid surface echo is received.

[0079] For example, the formula for calculating the liquid level inside the tank to be tested is:

[0080] Where h is the liquid level in the tank under test, t1 is the moment when the measuring probe emits the mechanical vibration wave, t2 is the moment when the measuring probe receives the liquid surface echo, v is the speed at which the mechanical vibration wave travels through the liquid in the tank under test, p is the focal length of the parabolic reflector, and h O h is the height of the second feature point O. O =q×sin(α), where q is the distance between the first feature point Δ and the first preset point T, α is the angle between the emission direction of the main beam of the mechanical vibration wave and the horizontal plane, the first feature point Δ is the intersection of the central axis of the primary reflection beam and the planar reflecting surface of the steering gear, the second feature point O is the intersection of the central axis of the primary reflection beam and the parabolic reflecting surface of the steering gear, the primary reflection beam is the beam after the main beam of the mechanical vibration wave is reflected by the planar reflecting surface, and the first preset point T is the intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank under test when the main beam of the mechanical vibration wave passes through the tank under test.

[0081] The velocity v of mechanical vibration waves propagating in the liquid inside the test tank can be obtained through calibration.

[0082] For calibration purposes, in other embodiments of this application, the liquid level measurement system in all the above embodiments may further include: a calibrator and a calibration probe;

[0083] The calibrator is located inside the container to be tested and includes a reflective plane.

[0084] The calibration probe is also connected to the external liquid level gauge host. The calibration probe is used to emit calibration mechanical vibration waves to the reflecting plane from the outside of the tank to be tested, and to receive the calibration echo (the calibration echo is the calibration mechanical vibration wave reflected by the reflecting plane).

[0085] The mechanical vibration waves emitted by the calibration probe can be, for example, ultrasonic waves, infrasound waves, or mechanical vibration waves with the same parameters (such as frequency and amplitude) as those emitted by the aforementioned measurement probe.

[0086] The emission time of the mechanical vibration wave used for calibration, the reception time of the calibration echo, and the preset distance L can be used to calculate the speed v of the mechanical vibration wave propagating in the liquid inside the test tank.

[0087] The central axis of the main beam of the mechanical vibration wave used for calibration is perpendicular to the reflecting plane, so that the reflecting plane can reflect the main beam perpendicularly and receive it as an echo by the calibration probe.

[0088] When the main beam of the mechanical vibration wave used for calibration passes through the tank under test, the intersection of its central axis and the inner wall of the tank under test can be called the second preset point S1, and the distance from the second preset point S1 to the reflecting plane can be used as the aforementioned preset distance L.

[0089] The calibrator can be of any structure, as long as it contains the aforementioned reflective plane.

[0090] The following describes an exemplary structure of the calibrator, including:

[0091] The support rod and the reflective plane can be used to install the reflective plane into the tank to be tested.

[0092] Specifically, the calibrator consists of three standard-length support rods and a reflective plane. The length of the support rods is l. j Examples of lengths include 1000 mm or other lengths that are convenient for installation and calculation.

[0093] Please refer to Figure 15. One end of the support rod is fixed at point B on the reflecting plane, and the other end is installed at point A on the inner wall of the tank. The central axis of the main beam of the mechanical vibration wave used for calibration is perpendicular to point S2 on the plane reflecting surface. To achieve calibration, the following conditions must be met at each point:

[0094] The first line segment formed by the second preset point S1 and point S2 coincides with the second line segment formed by point A and point B, or is parallel and equal (it can also be said that points S1, S2, A, and B form a rectangle).

[0095] Under the above conditions, the aforementioned L is equal to the length l of the support rod. j .

[0096] In an exemplary embodiment, a method for measuring the liquid level of a steering gear based on the above embodiments is provided. Given that the steering gear has already been designed and manufactured, the liquid level measurement method includes:

[0097] Step A: Install the steering gear inside the tank to be tested according to the measurement position on the outer wall of the tank.

[0098] The measurement location is point T1, as mentioned above. Please refer to the previous introduction; it will not be repeated here.

[0099] After executing step A, the planar reflective surface of the steering gear can be positioned in the transmission direction of the probe at the measurement position, and the parabolic reflective surface is positioned on the transmission path of the primary reflected beam. The parabolic reflective surface can reflect the primary reflected beam to form a vertically upward secondary reflected beam. The primary reflected beam is obtained by reflecting the main beam of the mechanical vibration wave from the planar reflective surface. The transmission direction is perpendicular to the tangent plane at the measurement position on the outer wall of the tank to be tested.

[0100] Specifically, the planar reflector M1 can be installed according to its installation position and angle.

[0101] For the parabolic reflector M2, its focal point can be determined first, and the point on the primary reflection beam transmission path that is a distance p from the focal point can be designated as the mounting point of the parabolic reflector M2 (which can be called mounting point C). Alternatively, the point on the primary reflection beam transmission path that is a distance pq from point Δ can be designated as the mounting point C of the parabolic reflector M2. Here, p is the focal length of the parabolic reflector M2, and q is the focal length of the aforementioned planar reflector M1.

[0102] Let the installation point C coincide with the second characteristic point O of the parabolic reflector M2, let the parabolic reflector M2 face the first reflected beam, and make the line connecting point Δ and point C horizontal.

[0103] Step B: Set the probe at the measurement position on the outer wall of the tank to be tested.

[0104] When the measurement location is fixed, the execution order of steps A and B can be reversed or executed in parallel, which will not be elaborated here.

[0105] Step C: Use the probe to emit mechanical vibration waves towards the tank under test.

[0106] The main beam of the emitted mechanical vibration wave is the aforementioned main beam of mechanical vibration wave; when the aforementioned main beam of mechanical vibration wave passes through the tank, the intersection of its central axis and the outer wall is the aforementioned measurement position T1, and the intersection with the inner wall of the tank is the aforementioned first preset point T.

[0107] Step D: Record the moment when the probe emits the mechanical vibration wave and the moment when it receives the liquid surface echo.

[0108] The timing of the probe emitting the mechanical vibration wave and receiving the liquid surface echo are used to calculate the liquid level of the tank under test. For details, please refer to the aforementioned description, which will not be repeated here.

[0109] In other embodiments of this application, the above measurement method may further include the following steps:

[0110] Step E: Calculate the liquid level inside the tank under test based on the time when the measuring probe emits the mechanical vibration wave and the time when it receives the liquid surface echo.

[0111] Please refer to the aforementioned records; they will not be repeated here.

[0112] In the above embodiments, the steering gear has been designed and manufactured. In other embodiments of this application, the steering gear can also be designed during the measurement process.

[0113] The following explanation uses a spherical tank as an example. The above measurement method may include the following steps:

[0114] The first step is to select the measurement position T1 of the spherical tank and measure the inclination angle β between the tangent plane of the outer wall of the tank at point T1 and the horizontal plane.

[0115] A point can be selected as measurement position T1 around the manhole flange near the vertical centerline of the spherical tank at the bottom. The inclination angle β between the tangential plane of the tank's outer wall and the horizontal plane is then measured based on the selected point. For details, please refer to the description of step S1 above, which will not be repeated here.

[0116] The second step is to establish coordinate system 1.

[0117] Specifically, a right-handed rectangular three-dimensional coordinate system TXYZ is established with the first preset point T as the origin, hereinafter referred to as coordinate system 1.

[0118] The third step is to determine the focal length q of the planar reflecting surface, the first feature point Δ, and the focal point T' of the parabolic reflecting surface. The specific determination method can be found in the previous record and will not be repeated here.

[0119] Step 4: Establish coordinate system 2.

[0120] Specifically, a right-handed three-dimensional rectangular coordinate system T'X'Y'Z' is established with T' as the origin, hereinafter referred to as coordinate system 2.

[0121] The fifth step is to design the installation angle and position of the planar reflective surface M1.

[0122] Please refer to the aforementioned relevant records, which will not be repeated here.

[0123] Step 6: Determine the divergence angle 2θ0 of the probe's main beam.

[0124] Step 7: Calculate the intersection point of the main beam edge ray and the plane reflecting surface M1 based on the probe divergence angle 2θ0, and use it as the first minimum edge position.

[0125] Step 8: Based on the first minimum edge position, fabricate a planar reflector M1' containing a planar reflective surface M1.

[0126] Step 9: Define p as the length of the line segment T'O, and with p as the focal length, use the parabola formula x' 2 =2py', input the value of x' to get the parabola b on the T'X'Y' coordinate plane. Rotate the parabola b horizontally with the coordinate axis T'Y' as the rotation axis to generate the target parabolic surface B.

[0127] Step 10: Design parabolic reflector M2 based on the target parabolic surface B, and fabricate parabolic reflector plate M2' with parabolic reflector M2.

[0128] Please refer to the aforementioned relevant records, which will not be repeated here.

[0129] Step 11: Make auxiliary components.

[0130] For example, it may include a reflector bracket and the wave-damping mechanism mentioned later.

[0131] Step 12: Install the planar reflector M1' and the parabolic reflector M2' using the aforementioned reflector bracket according to the designed installation position and angle, thus forming a full-energy double-reflection steering gear for measuring the liquid level outside the spherical tank. Then, install the aforementioned anti-wave mechanism around the steering gear.

[0132] Step 13: Use the spherical tank's acoustic energy diverter to measure the liquid level in the spherical tank.

[0133] For instructions on how to obtain the liquid level, please refer to the aforementioned records; they will not be repeated here.

[0134] The diverter in the above embodiments can be applied not only to spherical tanks, but also to vertical tanks and other irregularly shaped tanks for liquid level measurement.

[0135] The following describes how it can be applied to vertical tanks.

[0136] As shown in Figure 8, a right-handed rectangular three-dimensional coordinate system ΔX”Y”Z” is established with point Δ as the origin, referred to as coordinate system 3 (Figure 8(a) is the front view, and Figure 8(b) is the left view). The horizontal coordinate axis ΔX” of coordinate system 3 is parallel to the horizontal coordinate axis T'X' of coordinate system 2, and also parallel to the horizontal coordinate axis TX of coordinate system 1, i.e., ΔX” / / T'X' / / T1X. The coordinate axes ΔY”, ΔX”, and ΔZ” are perpendicular to each other. The ultrasonic incident ray T1Δ lies in the incident plane ΔT1X”. The incident plane ΔTX” can rotate around the horizontal coordinate axis ΔX”. The angle between the incident plane ΔT1X” and the vertical coordinate plane ΔX”Y” of coordinate system 3 is the incident angle γ (as shown in Figure 8(b)). The incident angle γ can be any angle. Let the incident angle γ be 0 degrees when the incident plane ΔT1X” coincides with the vertical coordinate plane ΔX”Y” of coordinate system 3, for example, in a spherical tank. The incident angle γ is 90 degrees when the incident plane ΔT1X” coincides with the horizontal coordinate plane ΔX”Z” of coordinate system 3, which is the case for a vertical tank, as shown in Figure 9. Figure 9(a) is a top view, Figure 9(b) is a front view, and Figure 9(c) is a left view. It should be noted that when applied to a vertical tank, TZ and T'Z' in coordinate systems 1 and 2 are vertically downwards, TY is perpendicular to the TXZ plane and outwards from the paper output plane, and T'Y' is perpendicular to the T'X'Z' plane and outwards from the paper output plane.

[0137] In this application, the incident angle β of the ultrasonic wave emitted by the probe can vary between -30° and 30°. The incident angle γ can be any angle, as shown in Figure 8(b). For example, for the spherical tank shown in Figures 2-3, the incident angle γ = 0°. For the vertical tank shown in Figure 9, the incident angle γ = 90°. For irregularly shaped containers with complex shapes, the incident angle γ can be other angles, as long as the angle between the normal of the plane reflecting surface M1 and the ultrasonic incident ray TΔ is equal to the angle between the normal and the ultrasonic outgoing ray ΔO of the plane reflecting surface M1 and equal to α / 2, it can be ensured that the central axis of the main ultrasonic beam emitted by the probe is reflected by the plane reflecting surface M1 and then directed towards the characteristic point O of the second parabolic reflecting surface M2. Given that the ultrasonic wave direction angle β emitted by the probe can vary between -30° and +30°, that is, the angle α between the incident cone angle C of the ultrasonic wave emitted by the probe and the horizontal coordinate axis ΔX” of the third coordinate system can vary between +60° and -60°, and that the angle γ between the incident plane ΔT1X” of the ultrasonic wave emitted by the probe and the vertical coordinate plane ΔX”Y” of the coordinate system 3 (i.e., the incident plane angle) can be any angle, as long as the angle between the normal of the plane reflecting surface M1 and the ultrasonic wave incident ray TΔ is equal to the angle between the normal and the ultrasonic wave exiting ray ΔO of the plane reflecting surface M1 and equal to α / 2, it can be guaranteed that the central axis of the main ultrasonic wave beam emitted by the probe is reflected by the characteristic point Δ of the plane reflecting surface M1 and then directed to the characteristic point O of the second parabolic reflecting surface M2. Therefore, the deflector method of this application is a flexible "omnidirectional" deflector method that can be widely applied to the requirements of various complex containers such as spherical tanks, vertical tanks, and sausage tanks.

[0138] It should be noted that in the aforementioned scheme, the measurement location (installation location) is selected first, followed by design and installation.

[0139] In other embodiments of this application, other design and installation methods may also be used. For example, since the target liquid surface is horizontal, the horizontal placement state of the parabolic reflector M2 can be determined first, that is, the focal line T'O of the horizontally placed M2 can be determined first. Then, the installation position of the probe on the container can be determined according to the focal length of the parabolic reflector M2 and the structure of the tank container. Then, according to the structure of the tank container, the incident plane angle γ of the probe ultrasonic wave, the incident horizontal angle β of the probe ultrasonic wave, and the distance q between the probe and the characteristic point Δ of the planar reflector M1 at the corresponding point T on the inner wall of the tank can be determined. The position of the characteristic point Δ in coordinate system 1 (q*cos(α), q*sin(α), 0) can be determined. The vertical angle α / 2 and the horizontal angle 90°-α / 2 of M1 can be determined.

[0140] In the application of the above embodiments, taking a spherical tank as an example, when liquid is poured into the tank from the bottom, the violent flow of liquid causes the ultrasonic waves in the bottom layer of liquid to deviate from their original propagation direction. The strong waves affect the liquid level measurement and generate a large number of bubbles that block the propagation of ultrasonic waves. When the liquid is emptied, the external liquid level gauge does not receive the echo signal and the measurement is interrupted. When liquid is poured in again, the external liquid level gauge starts searching for the liquid level again, sometimes displaying a false double liquid level with "secondary echo". The so-called "secondary echo" refers to the phenomenon that the ultrasonic echo reflected from the liquid surface is reflected back by the inner wall of the spherical tank near the probe, and then emitted again towards the liquid surface and reflected back to the probe, forming a phenomenon where multiple liquid surface echoes are obtained from one ultrasonic signal.

[0141] The embodiments of this application can solve these problems by setting up a wave-blocking mechanism, which can form a groove-shaped space (which can be called a wave-blocking groove) together with the inner wall of the tank to be tested; the steering device is set in the groove-shaped space.

[0142] The shape of the wave-damping mechanism can be any shape, but it must meet the following conditions:

[0143] A first ray is drawn from any point on the planar reflective surface along a first preset direction, and this first ray intersects with the side wall of the wave-damping mechanism; the first preset direction is: a horizontal direction away from the parabolic reflective surface.

[0144] A second ray is drawn along a second preset direction from any point on the parabolic reflective surface, and this second ray intersects with the side wall of the wave-damping mechanism; the second preset direction is: a horizontal direction away from the planar reflective surface.

[0145] For example, four flat plates are fixed to the periphery of the support around the planar reflector M'1 and the parabolic reflector M'2 to form a trapezoidal wave-damping channel. These four flat plates constitute an exemplary structure of the wave-damping mechanism. The height of the parabolic reflector M'2 end of the wave-damping channel is equal to (or higher than) the upper edge of M'2, and the height of the planar reflector M'1 end of the wave-damping channel is equal to (or higher than) the upper edge of M'1, as shown in Figure 10. Figure 10(a) is a front view of the wave-damping channel installation, Figure 10(b) is a right view of the deflector with the wave-damping channel externally installed, and Figure 10(c) is a top view of the wave-damping channel. The lower ends of the four flat plates of the wave-damping channel are placed on the inner wall of the spherical tank. When the liquid in the spherical tank is emptied, liquid will be stored in the wave-damping channel. After the liquid level in the spherical tank drops to the port of the planar reflector in the breakwater, the rapid descent of the liquid in the breakwater stops. During the period when the spherical tank is emptied, the external liquid level gauge of the diverter continuously and automatically tracks and measures the liquid level. This prevents the liquid level from doubling when the measurement is interrupted after the spherical tank is emptied and when liquid is refilled and the liquid level is searched again. The impact and air bubbles generated by the liquid entering from the bottom of the spherical tank are blocked by the breakwater and do not enter between the planar reflector M'1 and the parabolic reflector M'2, thus not affecting the normal measurement of the liquid level. A moderate gap is left between the lower edge of the breakwater mechanism and the bottom of the spherical tank, so that the liquid level in the breakwater drops more slowly than the liquid level outside the breakwater, and the liquid level in the breakwater rises again when liquid is refilled. The gap at the bottom of the breakwater also allows sediment in the liquid in the breakwater to flow out.

[0146] It should be noted that the shape of the enclosure of the wave-damping mechanism in this application is not limited. It does not necessarily have to have the four side plates mentioned above, as long as it can form a channel-shaped space that can accommodate the steering gear and meet the above conditions.

[0147] The design method of the above-mentioned steering system is illustrated below using a spherical tank as an example. Examples include:

[0148] S1: Select the measurement position T1 of the tank to be tested, and determine the horizontal inclination angle of the outer wall of the tank to be tested at the measurement position T1, which is taken as the horizontal angle β of the exit end face of the mechanical vibration wave.

[0149] For example, the measurement position T1 (also known as the measurement point or installation position) of the probe can be selected around the manhole flange near the vertical centerline of the spherical tank at the bottom of the tank. The horizontal tilt angle β of the outer wall of the spherical tank is also the horizontal tilt angle of the working end face of the probe, and T1 is the center point of the working end face of the probe.

[0150] In actual measurement, after the probe is installed at the measurement location, mechanical vibration waves, such as ultrasonic waves, can be emitted from the probe to the tank under test.

[0151] The sound pressure of the ultrasonic wave emitted by the probe at point T1 in the far field region consists of a main beam and a group of weak side lobes. The central axis of this main beam penetrates the tank wall at point T, perpendicular to the tank wall. The divergence angle of the main beam emitted from point T into the tank along the normal direction of the tangent plane of the inner wall is 2θ0, where θ0 is the half-divergence angle. The normal to the tangent plane of the inner wall of the tank at point T is the central axis of the main beam. The maximum sound pressure emitted by the probe along the central axis of the main beam is denoted as 100%. As the emission angle θ deviates from the central axis of the main beam, the sound pressure decreases. When the emission angle θ equals the half-divergence angle θ0, the sound pressure decreases to 0. The energy of the ultrasonic wave emitted by the probe is mainly concentrated in the main beam.

[0152] As an example, the diameter D of the ultrasonic probe chip is 45 mm, the resonant frequency f = 200 kHz, the speed of sound in water at 20℃ is c = 1480 m / s, and the wavelength λ = c / f = 7.4 mm. It can be calculated that the half-divergence angle θ0 = 70λ / D = 11.5° of the main beam of the ultrasonic wave emitted by the probe in water, thus the divergence angle 2θ0 = 23°.

[0153] S2: Determine the installation position and angle of the planar reflector M1 in the steering gear based on the horizontal angle β.

[0154] The steering gear includes a planar reflector M1 and a parabolic reflector M2.

[0155] For example, the installation position and installation angle can be determined as follows: on the propagation path of the main ultrasonic beam, select a point Δ that is q away from point T as the first feature point.

[0156] The first feature point Δ can be used as the installation position of the planar reflector M1. In addition, point Δ is the marker point of the planar reflector M1 obtained after the design is completed.

[0157] The installation angle of the planar reflector can be the angle between the planar reflector and the vertical direction, and its value is α / 2. Here, α is the angle between the central axis of the probe's working end face and the horizontal coordinate axis TX of coordinate system 1, α = 90° - β.

[0158] The above installation angle ensures that the central axis of the primary reflected beam obtained by the planar reflector M1 is located on a horizontal plane.

[0159] In one example, for a spherical tank, please refer to Figures 2-3. To facilitate understanding of the installation angle, the following explanation is based on coordinate system 1. The coordinate axis TX of coordinate system 1 is horizontally to the right, the coordinate axis TY is vertically upward, and the coordinate axis TZ is horizontally out of the paper.

[0160] In Figures 2 and 3, the plane reflecting surface M1 makes an angle of α / 2 with the positive direction of the TY coordinate axis and is parallel to the TZ coordinate axis. The length q can be called the focal length q of the plane reflecting surface M1.

[0161] It should be noted that in practical applications, if the probe is installed at position T1, which is between the central axis of the spherical tank and the right side of the manhole, then the right side of the tank wall at the probe installation position is higher than the left side. The characteristic point Δ of the planar reflector is located to the upper left of T1, and the parabolic reflector is located to the upper right of T1 (see Figure 2). Conversely, if the probe is installed at position T1, which is between the central axis of the spherical tank and the left side of the manhole, then the left side of the tank wall at the probe installation position is higher than the right side. The characteristic point Δ of the planar reflector is located to the upper right of T1, and the parabolic reflector is located to the upper left of T1 (see Figure 3). In short, the characteristic point Δ of the planar reflector is always in the direction of the spherical tank's central axis at the probe installation position T1.

[0162] Based on the installation location and angle, a plane can be designed. By cutting this plane according to certain requirements, the planar reflecting surface M1 can be obtained. This application will be further described later.

[0163] S3: Determine the first preset point T as the mirror symmetric point T' of the planar reflecting surface M1, and use it as the focus of the parabolic reflecting surface.

[0164] After determining the installation position and angle of the planar reflector M1, the transmission path of the aforementioned primary reflected beam can be obtained. A point can be selected on the reverse extension line of its transmission path as the first preset point T, which is the mirror symmetric point T' of the planar reflector M1. The distance between this point and point Δ is equal to q.

[0165] For example, as shown in Figures 2 and 3, a point T' can be defined as the point Δ at a distance q along the negative direction of the coordinate axis TX (which is opposite to the transmission path of the first reflected beam).

[0166] S4: Determine the second characteristic point O of the parabolic reflecting surface M2.

[0167] A point located at a distance p from the focal point along the target direction can be designated as the second feature point O. The target direction is the direction from the focal point to point Δ.

[0168] In fact, the target direction mentioned above is consistent with the transmission path of the first reflected beam.

[0169] For ease of understanding, please refer to Figures 2 and 3. The coordinate axis T'X' of coordinate system 2 is parallel to the coordinate axis TX of coordinate system 1, i.e., T'X' / / TX, and both points to the right in the same horizontal direction. The coordinate axes T'X', T'Y', and T'Z' are perpendicular to each other in the order of a right-handed three-dimensional coordinate system. The point at a distance p from point T' in the positive direction of the T'X' coordinate axis in coordinate system 2 (in Figures 2 and 3, this positive direction is the target direction mentioned above, which is consistent with the transmission path of the first reflected beam) can be defined as the second feature point O.

[0170] S5: Determine the target parabolic surface B based on the second feature point.

[0171] The target parabolic surface B can be obtained in the following way:

[0172] With point T' as the focus and distance p as the focal length, draw a parabola b through point O, as shown in Figure 6.

[0173] Rotate the parabola b horizontally with the vertical coordinate axis T'Y' of coordinate system 2 as the rotation axis (which is also the axis of symmetry of parabola b) to form the target parabolic surface B.

[0174] Subsequently, a portion of the curved surface on the target parabolic surface B can be intercepted as the parabolic reflecting surface M2. Of course, in some cases, the target parabolic surface B may be directly used as the parabolic reflecting surface M2. The feature point O on the parabola b is the second feature point of the parabolic reflecting surface M2. The origin T' of coordinate system 2 is the focus of the parabolic reflecting surface M2, and the focal length p of the parabola b is the focal length of the parabolic reflecting surface M2.

[0175] As can be seen, the ultrasonic rays of the main ultrasonic beam along the central axis are reflected by the planar reflecting surface M1 and propagate a distance pq along the negative direction of the T'X' coordinate axis of coordinate system 2 to the characteristic point O of the parabolic reflecting surface M2. Reflected by the parabolic reflecting surface, they are directed vertically upwards towards the liquid surface along the T'Y' coordinate axis of coordinate system 2. The ultrasonic signal of the central axis of the main ultrasonic beam is reflected by the liquid surface to form the liquid surface echo signal, which returns to the characteristic point O of the parabolic reflecting surface M2 along the negative direction of the T'Y' coordinate axis of coordinate system 2. After being reflected by the parabolic reflecting surface M2, it is directed towards the characteristic point Δ of the planar reflecting surface M1. After being reflected by the planar reflecting surface M1, it is directed towards the origin T of coordinate system 1 (i.e., the TXYZ coordinate system).

[0176] The following proof demonstrates that the angle between the planar reflecting surface M1 and the vertical coordinate axis TY is α / 2. In Figure 7, an auxiliary line y is drawn through point Δ, parallel to the coordinate axis TY. The auxiliary line s is perpendicular to line segment TΔ, and the auxiliary line u is perpendicular to the planar reflecting surface M1. The angle between the tangent plane of the probe end face and the outer wall of the spherical tank at the center point T1 of the probe end face and the line parallel to the coordinate axis TX passing through point T1 is β. A perpendicular line is drawn through point T1 to the wall of the spherical tank. The intersection of this perpendicular line and the inner wall of the spherical tank is point T. The extension of line segment T1T, perpendicular to the wall of the spherical tank, passes through point Δ. Because the line T1Δ is perpendicular to the tangent plane of the outer wall of the spherical tank passing through point T1, the angle between the line T1Δ and the auxiliary line y, parallel to the coordinate axis TY, is equal to β. Because the auxiliary line s is perpendicular to the line T1Δ, the angle between the auxiliary line s and the auxiliary line y is equal to 90° - β = α. Let the angle between the plane reflecting surface M1 and the auxiliary line y be 'a', the angle between the plane reflecting surface M1 and the auxiliary line s be 'c', and the angle between the auxiliary line u and the coordinate axis ΔX' of the second coordinate system be 'd'. The incident angle of the central axis of the main ultrasonic beam emitted by the probe at the marked point Δ on the plane reflecting surface M1 is equal to the exit angle, which means the angle between the auxiliary line u and ΔX' is equal to the angle between the auxiliary line u and TΔ, which is 'd'. Therefore, angle a + c = c + d = d + d = α, so angle a = c = d = α / 2. Finally, we can conclude that the angle between the plane reflecting surface M1 and the vertical coordinate axis TY is equal to α / 2.

[0177] The following explains how to determine the dimensions of planar and parabolic reflective surfaces:

[0178] When the detection intensity requirement is to completely reflect the main beam of the mechanical vibration wave, in one example, as shown in Figure 13, the intersection point of the edge ray of the main beam and the target plane N can be calculated based on the divergence angle 2θ0 of the main beam of the probe, and the first minimum edge position D1 can be determined.

[0179] The target plane N is the plane drawn based on the aforementioned installation position and installation angle.

[0180] When complete reflection is required, the area covering the first target region can be designated as the planar reflective surface M1, and the first target region is determined by the first minimum edge position D1. Therefore, the first minimum edge position D1 is located at the edge of the planar reflective surface M1 or inside the planar reflective surface M1.

[0181] Accordingly, an exemplary parabolic reflective surface can be determined as follows:

[0182] The intersection point of the edge ray e of the primary reflected beam and the aforementioned target parabolic surface B is determined as the second minimum edge position D2. Based on the second minimum edge position D2, the size of the parabolic reflector surface on the target parabolic surface B can be determined. This ensures that the second minimum edge position D2 is located at the edge of the parabolic reflector surface or inside the parabolic reflector surface.

[0183] It should be noted that once the installation position, installation angle, dimensions, measurement position, second feature point, focal length p, etc. of the planar reflector M1 are determined, the edge ray e of the primary reflected beam can be drawn.

[0184] For example, in the case of total reflection, when the probe installation position T1 is to the right of the center line of the spherical tank, as shown in Figure 2, a conical surface with an angle of 2θ0 is drawn along the positive direction of the horizontal coordinate axis T'X' of coordinate system 2. The intersection of this conical surface and the parabolic reflective surface M2 is the second minimum edge position D2 of the parabolic reflective surface M2, and the central axis of the conical surface is T'O. When the probe installation position T1 is to the left of the center line of the spherical tank, as shown in Figure 3, a conical surface with an angle of 2θ0 is drawn along the negative direction of the horizontal coordinate axis T'X' of coordinate system 2, which determines the second minimum edge position D2 of the parabolic reflective surface M2.

[0185] In other embodiments of this application, a 2θ0 conical surface can be made, and the intersection of the 2θ0 conical surface and the parabola b (the intersection includes part of the aforementioned second minimum edge position D2) can be used as the minimum parabola segment. This minimum parabola segment can be rotated horizontally about the vertical coordinate axis T'Y' of coordinate system 2 to form a parabola. The resulting parabola can be directly used as the parabola reflecting surface M2, as shown in Figure 14.

[0186] In other embodiments of this application, a combined diverter that uses partial reflective surfaces to reduce volume can be designed, i.e., by requiring partial reflection of the main beam of the mechanical vibration wave, as shown in Figure 11. The specific design method for determining the dimensions of the planar reflective surface and the parabolic reflective surface is as follows:

[0187] The first minimum edge position is determined by the intersection point of the edge ray of the main beam of the mechanical vibration wave emitted from the measurement position and the target plane. The edge ray of the main beam of the mechanical vibration wave is determined based on the divergence angle of the main beam of the mechanical vibration wave. The target plane is a plane constructed according to the installation position and installation angle. For details, please refer to the foregoing description, which will not be repeated here.

[0188] Based on the proportion of partial reflection to total reflection, a section is extracted within the first target area to obtain a planar reflective surface that meets the requirements for partial reflection.

[0189] The design of the parabolic reflector can be found in the previous description and will not be repeated here.

[0190] Once the design is complete, the aforementioned steering gear can be manufactured.

[0191] For example, a material with an acoustic impedance much greater than that of the liquid being measured, such as steel, can be used to make a planar reflector M'1 with the planar shape of the planar reflector M1 and a parabolic reflector M'2 with the parabolic shape of the parabolic reflector M2.

[0192] For example, a bracket Z can be made of a robust and corrosion-resistant material to fix the planar reflector M'1 and the parabolic reflector M'2. The planar reflector M'1 and the parabolic reflector M'2 are precisely installed on the bracket Z. The distance between the marked point Δ of the planar reflector M'1 and the origin T of coordinate system 1 (i.e., the TXYZ coordinate system) is q. In coordinate system 1, the coordinates of Δ are (q*cos(α), q*sin(α), 0). The feature point Δ of the planar reflector is located on the center line of the spherical tank at the probe installation position T1. When T1 is to the right of the center line of the spherical tank, the feature point Δ of the planar reflector is to the left of T1. In coordinate system 2 (i.e., coordinate system T'X'Y'Z'), the angle between the planar reflector M'1 and the positive direction of the horizontal coordinate axis T'X' is 90°-α / 2. When T1 is to the left of the center line of the spherical tank, the feature point Δ of the planar reflector is to the right of T1. The angle between the planar reflector M'1 and the negative direction of the horizontal coordinate axis T'X' is 90°-α / 2, and the angle between the planar reflector M'1 and the vertical coordinate axis T'Y' is α / 2. The line connecting the marker point Δ of the planar reflector M'1 and the feature point O of the parabolic reflector lies on the horizontal coordinate axis T'X' of the second coordinate system T'X'Y'Z'. The length of the line ΔO connecting the marker point Δ of M'1 to the feature point O of the parabolic reflector M'2 is equal to Pq, where P is the focal length of the parabolic reflector and q is the distance from the origin T of the first coordinate system TXYZ to the marker point Δ of the planar reflector M'1.

[0193] The key application point of this application is that, since the liquid surface is horizontal, it is necessary to first determine the horizontal placement state of the second reflecting surface M2, that is, to first determine the focal line T'O of the horizontally placed M2. Then, based on the focal length of the parabolic reflecting surface M2 and the structure of the container, the installation position of the probe on the container is determined. Then, based on the structure of the container, the incident plane angle γ and incident horizontal angle β of the ultrasonic wave of the probe are determined in sequence, as well as the distance q between the point T on the inner wall of the tank corresponding to the probe and the marked point Δ of the first reflecting surface M1. Then, the position of the marked point Δ in the first coordinate system (q*cos(α), q*sin(α), 0) is determined, and the vertical angle α / 2 of M1 is determined.

[0194] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0195] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A steering system, characterized in that, The steering mechanism includes: a planar reflective surface and a parabolic reflective surface; The planar reflector is used to reflect the main beam of the mechanical vibration wave to form a primary reflected beam; The parabolic reflector is located on the transmission path of the primary reflected beam and is used to reflect the primary reflected beam to form a secondary reflected beam. The secondary reflected beam is a parallel beam and its direction is vertically upward. Wherein, the first preset point T coincides with the focal point of the parabolic reflective surface with respect to the mirror symmetry point of the planar reflective surface; the first preset point T is the intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank to be tested when the main beam of the mechanical vibration wave passes through the tank. The central axis of the primary reflection beam is located on a horizontal plane; the central axis of the primary reflection beam intersects the planar reflecting surface at a first feature point Δ and the parabolic reflecting surface at a second feature point O; the distance between the first feature point Δ and the second feature point O is less than p, where p is the focal length of the parabolic reflecting surface.

2. The steering system according to claim 1, characterized in that, The angle between the planar reflecting surface and the vertical direction is α / 2, where α+β=90°, and β is the horizontal angle of the exit end face of the main beam of the mechanical vibration wave.

3. The steering system according to claim 1, characterized in that, The planar reflecting surface is used to reflect all or part of the main beam of the mechanical vibration wave, and the parabolic reflecting surface is used to reflect all or part of the primary reflection beam.

4. The steering system according to claim 1, characterized in that, The distance between the focal point and the first feature point Δ is q, the distance between the first feature point Δ and the first preset point T is q, and the distance between the first feature point Δ and the second feature point O is pq, where q is less than p.

5. A liquid level measurement system, characterized in that, The liquid level measurement system includes: a measurement probe and a diverter as described in any one of claims 1-4; During measurement, the measuring probe is placed outside the tank to be measured and is used to emit mechanical vibration waves into the tank; wherein, the main beam of the emitted mechanical vibration wave is the main beam of the mechanical vibration wave. The deflector is installed inside the tank to be tested, and the planar reflective surface of the deflector is located in the emission direction of the main beam of the mechanical vibration wave.

6. The liquid level measurement system according to claim 5, characterized in that, The liquid level measurement system also includes: an external liquid level gauge main unit; The external liquid level gauge main unit is connected to the measuring probe; The external liquid level gauge main unit is used to calculate the liquid level in the tank under test based on the time when the measuring probe emits mechanical vibration waves and the time when it receives the liquid surface echo.

7. The liquid level measurement system according to claim 6, characterized in that, The formula for calculating the liquid level inside the tank to be tested is: Where h is the liquid level in the tank under test, t1 is the moment the measuring probe emits the mechanical vibration wave, t2 is the moment the measuring probe receives the liquid surface echo, v is the speed at which the mechanical vibration wave travels through the liquid in the tank under test, p is the focal length of the parabolic reflector, and h O h is the height of the second feature point O. O =q×sin(α), where q is the distance between the first feature point Δ and the first preset point T, α is the angle between the emission direction of the main beam of the mechanical vibration wave and the horizontal plane, the first feature point Δ is the intersection of the central axis of the primary reflection beam and the planar reflecting surface of the steering gear, the second feature point O is the intersection of the central axis of the primary reflection beam and the parabolic reflecting surface of the steering gear, the primary reflection beam is the beam after the main beam of the mechanical vibration wave is reflected by the planar reflecting surface, and the first preset point T is the intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank under test when the main beam of the mechanical vibration wave passes through the tank under test.

8. The liquid level measurement system according to claim 6, characterized in that, The liquid level measurement system further includes: a calibrator and a calibration probe; the calibrator includes a reflective plane; The calibrator is located inside the tank to be tested; The calibration probe is connected to the external liquid level gauge host. The calibration probe is used to emit calibration mechanical vibration waves to the reflecting plane from the outside of the tank to be tested, and to receive calibration echoes. The calibration echoes are calibration mechanical vibration waves reflected by the reflecting plane. The emission time of the calibration mechanical vibration wave, the reception time of the calibration echo, and the preset distance L are used to calculate the speed v of the mechanical vibration wave propagating in the liquid inside the test tank. Wherein, the central axis of the main beam of the calibration mechanical vibration wave is perpendicular to the reflection plane; the preset distance L is the distance from the second preset point S1 to the reflection plane; The second preset point S1 is the intersection of the central axis of the main beam of the calibration mechanical vibration wave and the inner wall of the tank under test when the main beam passes through the tank under test.

9. The liquid level measurement system according to claim 8, characterized in that, The reflective plane is installed in the tank to be tested via a support rod; wherein, one end of the support rod is fixed to point A on the inner wall of the tank to be tested, and the other end is connected to the reflective plane at point B; The central axis of the main beam of the mechanical vibration wave used for calibration is perpendicular to a point S2 on the planar reflecting surface; The first line segment formed by the second preset point S1 and point S2 coincides with the second line segment formed by point A and point B, or is parallel and equal in length. The preset distance L is equal to the length of the support rod.

10. The liquid level measurement system according to any one of claims 5-9, characterized in that, The liquid level measurement system also includes: a wave-proof mechanism; The wave-damping mechanism can form a groove-shaped space together with the inner wall of the tank to be tested; the steering device is disposed within the groove-shaped space; Wherein, a first ray is drawn from any point on the planar reflective surface along a first preset direction, and this first ray intersects with the side wall of the wave-damping mechanism; the first preset direction is: a horizontal direction away from the parabolic reflective surface; A second ray is drawn from any point on the parabolic reflective surface along a second preset direction, and this second ray intersects with the side wall of the wave-damping mechanism; the second preset direction is a horizontal direction away from the planar reflective surface.

11. The liquid level measurement system according to claim 8 or 9, characterized in that, The external liquid level gauge host is also used to: calculate the speed v of mechanical vibration wave transmission in the liquid inside the tank to be tested, based on the preset distance L, the time t′1 when the calibration probe emits the calibration mechanical vibration wave and the time t′2 when the calibration mechanical vibration wave reflected by the reflecting plane is received, using the following formula; v = 2L / (t'2-t'1).

12. A method for measuring liquid level, characterized in that, The liquid level measurement method uses the diverter according to any one of claims 1-4, and the liquid level measurement method includes: Set the measuring probe at the measuring position on the outer wall of the tank to be tested; A deflector is installed inside the tank under test so that the planar reflector surface of the deflector is located in the emission direction of the measuring probe, and the parabolic reflector surface is located on the transmission path of the primary reflected beam, and the parabolic reflector surface can reflect the primary reflected beam to form a vertically upward secondary reflected beam; wherein, the primary reflected beam is obtained by reflecting the main beam of the mechanical vibration wave from the planar reflector surface; the emission direction is perpendicular to the tangent plane at the measurement position on the outer wall of the tank under test; A mechanical vibration wave is emitted towards the tank under test using a measuring probe; the main beam of the emitted mechanical vibration wave is the main beam of the mechanical vibration wave; when the main beam of the mechanical vibration wave passes through the tank under test, the intersection of its central axis with the outer wall of the tank under test is the measurement position, and the intersection with the inner wall of the tank under test is the first preset point T; Record the moment when the measuring probe emits mechanical vibration waves and the moment when it receives the echo from the liquid surface; The timing of the measurement probe emitting mechanical vibration waves and receiving liquid surface echoes are used to calculate the liquid level of the tank under test.

13. The liquid level measurement method according to claim 12, characterized in that, Also includes: The liquid level inside the tank under test is calculated based on the timing of the mechanical vibration wave emitted by the measuring probe and the timing of the liquid surface echo received.

14. A design method for a steering gear according to any one of claims 1-4, characterized in that, The design method includes: Select the measurement position T1 of the tank to be tested, and determine the horizontal inclination angle of the outer wall of the tank to be tested at the measurement position T1, which is taken as the horizontal angle β of the exit end face of the mechanical vibration wave; The installation position and angle of the planar reflector are determined based on the horizontal angle β; the installation position of the planar reflector is located in the emission direction of the main beam of the mechanical vibration wave; the installation angle of the planar reflector is the angle between the planar reflector and the vertical direction, and its value is α / 2; where α+β=90°; the installation position is used as the first characteristic point Δ of the planar reflector. Based on the installation position and installation angle, the first preset point T is determined to be the mirror symmetry point T' of the planar reflecting surface, which serves as the focal point of the parabolic reflecting surface; the first preset point T is the intersection of the central axis of the main beam of the mechanical vibration wave and the inner wall of the tank under test when the main beam passes through the tank under test; wherein, the straight line passing through the mirror symmetry point T', the first feature point Δ, and the second feature point O is a horizontal straight line; A point along the target direction and at a distance p from the focal point is identified as the second feature point O; the target direction is the direction from the focal point to the first feature point Δ. Based on the second feature point O and the focal point, a target parabolic surface is determined; wherein, a portion of the curved surface on the target parabolic surface serves as a parabolic reflector, or the target parabolic surface serves as a parabolic reflector. Based on the installation location, installation angle, and detection intensity requirements, the dimensions of the planar reflective surface are determined to obtain the designed planar reflective surface. The dimensions of the parabolic reflector are determined based on the target parabolic surface, resulting in the designed parabolic reflector.

15. The steering gear design method according to claim 14, characterized in that, When the required detection intensity is to completely reflect the main beam of the mechanical vibration wave, the dimensions of the planar reflecting surface are determined based on the installation position, installation angle, and detection intensity requirements, specifically including: The first minimum edge position is determined by the intersection point of the edge ray of the main beam of the mechanical vibration wave emitted at the measurement position and the target plane; the edge ray of the main beam of the mechanical vibration wave is determined based on the divergence angle of the main beam of the mechanical vibration wave; the target plane is a plane drawn according to the installation position and installation angle. The size of the planar reflective surface is determined on the target plane based on the first minimum edge position, such that any of the first minimum edge positions is located at the edge of the planar reflective surface or inside the planar reflective surface.

16. The steering gear design method according to claim 14, characterized in that, When the required detection intensity is partial reflection of the main beam of the mechanical vibration wave, the dimensions of the planar reflecting surface are determined based on the installation position, installation angle, and detection intensity requirements, specifically including: The first minimum edge position is determined by the intersection point of the edge ray of the main beam of the mechanical vibration wave emitted at the measurement position and the target plane; the edge ray of the main beam of the mechanical vibration wave is determined based on the divergence angle of the main beam of the mechanical vibration wave; the target plane is a plane drawn according to the installation position and installation angle. Based on the proportion of partial reflection to total reflection, a planar reflective surface that meets the partial reflection requirement is extracted from the first target area; wherein, the ratio of the area of ​​the planar reflective surface to the area of ​​the first target area conforms to the stated proportion; the first target area is the area determined on the target plane based on the first minimum edge position.

17. The design method of the steering gear according to any one of claims 14-16, characterized in that, The intersection point of the edge ray of the first reflected beam and the target parabolic surface is determined as the second minimum edge position; The size of the parabolic reflective surface is determined on the target parabolic surface based on the second minimum edge position, such that either of the second minimum edge positions is located at the edge of the parabolic reflective surface or inside the parabolic reflective surface.

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