Combined depth gauge and method for measuring the distance of the combustion chamber front wall from the evaporation tube

Abstract

The present application relates to the technical field of mechanical size measurement, and discloses a combined depth gauge for measuring the distance between the front wall of a combustion chamber and an evaporation pipe and a measuring method, comprising a reference positioning plate, a straight probe assembly, an L-shaped hook-shaped probe assembly, a digital reading module and a contact indication feedback module. The reference positioning plate is provided with a same reference surface and a single guide hole, the two probe assemblies are respectively in sliding fit with the guide hole, and the probe surface is provided with a local insulation structure. During measurement, the exposed metal contact surface of the probe assembly touches the metal surface inside the combustion chamber, so that the electric circuit is closed, and the contact indication feedback module is triggered to emit an audible and visual signal. The present application realizes coaxial measurement by the single guide hole cooperating with the two probes in steps, converts the fitting state into electric signal output, avoids the reference axis center deviation error of multi-hole measurement, reduces the error generated by relying on hand feeling judgment, and improves the accuracy of the space distance measurement in the visual line blind area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical size measurement, in particular to a combined depth gauge for measuring the distance between the front wall of a combustion chamber and an evaporation pipe and a measuring method. BACKGROUND

[0002] In the assembly process of an engine combustion chamber, the axial distance between the front wall of the combustion chamber and the evaporation pipe needs to be measured to ensure that the assembly position of the parts meets the size requirements of the drawings. Since the combustion chamber is a closed or semi-closed structure, the internal line of sight is blocked, and the operator cannot observe the contact condition of the measuring tool after it is inserted into the interior from the outside.

[0003] In order to obtain the position data of the two different depths of the inner surface of the front wall and the end surface of the evaporation pipe, a plurality of guide holes are usually provided on the reference plate for detection in the conventional measuring tool. The switching of the probe between different guide holes will cause the offset of the reference axis, thereby generating a positioning error. During the measurement process, since the operator cannot see the front end of the probe, he can only rely on the sense of touch to judge whether the probe has been attached to the internal metal surface. This judgment method will produce errors due to different human senses.

[0004] At the same time, due to the lack of accurate contact prompt, if the probe touches other metal parts in the narrow space when it is inserted, the operator is easy to mistakenly think that the probe has touched the bottom, resulting in deviation of the depth data obtained. The existing measurement method lacks a data verification step, so that the final calculated distance between the front wall and the evaporation pipe is not reliable. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a combined depth gauge for measuring the distance between the front wall of a combustion chamber and an evaporation pipe and a measuring method, which solves the problem of measurement error caused by non-uniform measurement reference and reliance on sense of touch to judge the contact state when measuring the distance between the front wall and the evaporation pipe in the combustion chamber with blocked line of sight in the prior art.

[0006] To achieve the above purpose, the present application is realized by the following technical scheme:

[0007] The present application provides a combined depth gauge for measuring the distance between the front wall of a combustion chamber and an evaporation pipe in the first aspect, comprising:

[0008] The system includes a reference positioning plate, a straight probe assembly, an L-shaped hook probe assembly, a digital display module, and a contact indication feedback module. The reference positioning plate has a common reference surface, an outer surface facing away from the same reference surface, a positioning step, and a guide hole. The straight probe assembly and the L-shaped hook probe assembly slide with the guide hole respectively. The front end of the straight probe assembly has a flat-headed contact plate, and the front end of the L-shaped hook probe assembly has a hook tip. The digital display module connects to the straight probe assembly and the L-shaped hook probe assembly, and is used to measure and display the axial displacement of either the straight probe assembly or the L-shaped hook probe assembly relative to the reference positioning plate, with the reference plate as a reference. The contact indication feedback module is electrically connected to the straight probe assembly and the L-shaped hook probe assembly and is configured to form an electrical circuit with the combustion chamber metal housing.

[0009] This device combines a mechanical axial measurement structure with an electrical signal contact feedback loop. In operation, the metal casing of the combustion chamber serves as the conductive medium for the electrical circuit. When the flat-head contact plate or hook tip contacts the inner surface of the combustion chamber's metal casing, the electrical circuit is activated, triggering the contact indication feedback module to issue an indication signal. This structure transforms the operator's reliance on tactile judgment of the end-face contact state into an electrical on / off signal, reducing structural deformation and reading deviations caused by the probe pressing against the measurement surface.

[0010] The reference positioning plate has only one guide hole on its entire surface, and a wear-resistant bushing with an axial length greater than the plate thickness is installed inside to maintain the perpendicular geometric relationship between the straight probe assembly or the L-shaped hook probe assembly and the same reference plane. The front end of the straight probe assembly uses a PTFE insulating sleeve to achieve electrical isolation between the flat-head contact plate and the probe body. The slender main rod and non-contact surface of the L-shaped hook probe assembly are tightly covered with PTFE heat-shrink tubing or an insulating ceramic coating, with only the rear contact surface of the hook tip facing the reference positioning plate remaining exposed metal. Simultaneously, the angle between the central axis of the hook tip and the central axis of the slender main rod is set to 90°±0.5° to ensure that the rear contact surface of the hook tip, in a vertical state, can form a surface contact with the straight end face of the evaporator tube inside the combustion chamber. Electrical wiring is led out through a hollow channel inside the probe body or the slender main rod and connected to a switching amplifier circuit with a switching transistor. The contact current generated by the closed loop drives an LED and a miniature buzzer to emit an audio alarm indication signal.

[0011] A second aspect of the present invention provides a method for measuring the distance between the combustion chamber front wall and the evaporator tube using a combined depth gauge, comprising the following steps:

[0012] The reference positioning plate is attached to and fixed to the rear wall of the combustion chamber, establishing a unified reference for the measurement operation. The electrical circuit connecting the contact indication feedback module and the combustion chamber metal housing is then established. A straight probe assembly with a digital display module is inserted into the guide hole, aligning the flat-head contact plate with the outer surface, and the digital display module is operated to perform a position zeroing setting. The straight probe assembly is pushed into the combustion chamber, stopping upon receiving an indication signal, and the currently displayed axial displacement is recorded as the depth measurement value of the inner surface of the front wall. The straight probe assembly is then completely withdrawn from the guide hole. An L-shaped hook probe assembly with a digital display module is inserted into the same guide hole of the reference positioning plate, aligning the hook tip with the outer surface, and the current digital display module is operated to perform a position zeroing setting. The L-shaped hook probe assembly is pushed into the combustion chamber until its travel depth exceeds the depth measurement value of the inner surface of the front wall. The L-shaped hook probe assembly is then pulled back, stopping upon receiving an indication signal, and the currently displayed axial displacement is recorded as the depth measurement value of the inner end face of the evaporator tube.

[0013] The above measurement procedure was repeated three times to obtain three sets of depth measurements of the inner surface of the front wall and three sets of depth measurements of the inner end face of the evaporator tube. Multiple data verification was performed on each set of inner surface depth measurements and evaporator tube depth measurements. The three sets of inner surface depth measurements or the three sets of evaporator tube depth measurements were compared separately, and the range between the maximum and minimum values ​​in each set was calculated. It was then determined whether the range was within the measurement tolerance threshold range of 0.01 mm to 0.03 mm. If the range was within the measurement tolerance threshold range, the data set was considered valid. After confirming the data validity, an arithmetic mean was calculated from the three valid data sets to obtain the average depth value of the inner surface of the front wall and the average depth value of the inner end face of the evaporator tube. Subsequently, the absolute difference between these two average depth values ​​was calculated and used as the axial distance between the inner surface of the combustion chamber front wall and the inner end face of the evaporator tube.

[0014] Before measurement, assemble a reference positioning plate whose outer diameter matches the inner diameter of the combustion chamber tail to ensure that the central axis of the guide hole is coaxial with the cylindrical surface of the positioning step; alternatively, replace with a straight probe assembly of different lengths, add a concentric extension rod, or replace with an L-shaped hook probe assembly with hook tips of different lateral extension lengths. After replacement, align the front end of the replaced straight probe assembly or the rear contact surface of the hook tip with the outer surface of the reference positioning plate, and re-execute the position zeroing setting to re-zero and align the detection end face of the replaced probe to the same reference plane.

[0015] This invention provides a combined depth gauge and measurement method for measuring the distance between the combustion chamber front wall and the evaporator tube. It has the following beneficial effects:

[0016] 1. The combined depth gauge of this invention features a single guide hole on the reference positioning plate, which, together with the straight probe assembly and the L-shaped hook probe assembly, performs coaxial measurements step by step. This structure avoids the cumulative error caused by the offset of the reference axis during multi-hole measurements, and places the detection process of the inner surface of the front wall with spatial obstruction and the inner end face of the evaporator tube under the same reference and coordinate system, thereby improving the accuracy of spatial distance calculation.

[0017] 2. This invention incorporates a contact indication feedback module and a localized insulating structure on the probe assembly surface. When measuring the internal structure of the combustion chamber in a blind spot, a closed electrical circuit is only formed and an audible and visual signal is triggered when the exposed metal contact surface at the probe tip touches the target surface. This design converts the contact state into an electrical signal output, reducing errors caused by operators judging the contact state by touch. Simultaneously, the insulating coating prevents the probe from touching other metal parts during insertion, thus avoiding misleading connections.

[0018] 3. The measurement method of this invention includes a data verification step. Before calculating the final spatial spacing, the range of multiple measurements at the same location is calculated. By comparing the range with a set measurement tolerance threshold, it is determined whether the data meets the requirements. Subsequently, the data that meets the requirements are arithmetically averaged. This data processing method eliminates deviation data caused by single probe posture deviation or unstable adhesion, ensuring the repeatability and reliability of the final obtained axial distance dimension. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the algorithm flow of the present invention;

[0020] Figure 2 This is a schematic diagram of the system architecture of the present invention;

[0021] Figure 3 This is a comparative diagram showing the change in system throughput with the number of access nodes under different schemes of the present invention;

[0022] Figure 4 This is a schematic diagram comparing the average processing delay of different schemes under high load conditions according to the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1 -Appendix Figure 2The present invention provides a combined depth gauge for measuring the distance between the front wall of the combustion chamber and the evaporator tube, which may include: a reference positioning plate 10, a straight probe assembly 20, an L-shaped hook probe assembly 30, a digital display reading module 40, and a contact indication feedback module 50.

[0025] The reference positioning plate 10 is provided with a common reference surface 13 and a guide hole 11. During the measurement operation, the common reference surface 13 of the reference positioning plate 10 is attached to the rear wall of the combustion chamber, providing a zero-point reference surface for the measurement. The guide hole 11 is used to pass through and guide the straight probe assembly 20 and the L-shaped hook probe assembly 30 into the interior of the combustion chamber.

[0026] The straight probe assembly 20 and the L-shaped hook probe assembly 30 pass through the guide hole 11 of the reference positioning plate 10 in a time-sequential manner during the measurement process. The guide hole 11 provides a unified insertion space axis for the straight probe assembly 20 and the L-shaped hook probe assembly 30, limiting the radial displacement of the probe assembly relative to the rear wall of the combustion chamber.

[0027] The straight probe assembly 20 has a flat-head contact plate 22 at its front end. The flat-head contact plate 22 is used to contact and sense the position of the inner surface of the front wall inside the combustion chamber during propulsion.

[0028] The L-shaped hook probe assembly 30 has a hook tip 32 at its front end. The hook tip 32 is used to contact and sense the position of the inner end face of the evaporator tube inside the combustion chamber during the pull-back process.

[0029] The rear ends of the straight probe assembly 20 and the L-shaped hook probe assembly 30 are each connected to a digital display reading module 40. The digital display reading module 40 cooperates with the reference positioning plate 10, using the reference positioning plate 10 as the zero point reference, to measure and display the axial displacement of the straight probe assembly 20 or the L-shaped hook probe assembly 30 relative to the reference positioning plate 10.

[0030] The contact indication feedback module 50 is connected to the straight probe assembly 20 and the L-shaped hook probe assembly 30. The contact indication feedback module 50 and the combustion chamber metal housing form an electrical circuit. When the flat contact plate 22 of the straight probe assembly 20 or the hook tip 32 of the L-shaped hook probe assembly 30 contacts the metal surface inside the combustion chamber, the electrical circuit is in a conductive state. The contact indication feedback module 50 emits an audible and visual indication signal based on the circuit's conductive state, indicating that the target end face has reached the contact state.

[0031] Please see the appendix Figure 1 This invention provides a method for measuring the distance between the combustion chamber front wall and the evaporator tube using a combined depth gauge, comprising the following steps:

[0032] S10, so that the same reference surface 13 of the reference positioning plate 10 is attached and fixed to the rear wall of the combustion chamber, a unified reference for measurement operation is established, and the contact indication feedback module 50 is connected to the electrical circuit where the metal shell of the combustion chamber is located.

[0033] S20, insert the straight probe assembly 20 with a set of digital display reading modules 40 into the guide hole 11 of the reference positioning plate 10, make the flat-headed contact plate 22 flush with the outer side of the reference positioning plate 10 and operate the digital display reading module 40 to perform the position zeroing setting, push the straight probe assembly 20 into the combustion chamber, and at the same time monitor the signal sent by the contact indication feedback module 50.

[0034] S30, when the contact indication feedback module 50 sends a conduction indication signal, the straight probe assembly 20 is stopped from advancing, and the value displayed by the digital display reading module 40 is recorded and used as the depth measurement value of the inner surface of the front wall.

[0035] S40, the straight probe assembly 20 is completely pulled out from the guide hole 11 of the reference positioning plate 10, and the L-shaped hook probe assembly 30 with a set of digital display reading modules 40 is inserted into the same guide hole 11 of the reference positioning plate 10, so that the hook tip 32 is flush with the outer side of the reference positioning plate 10 and the current digital display reading module 40 is operated to perform the position zero setting.

[0036] S50, the L-shaped hook probe assembly 30 is pushed into the combustion chamber so that its travel depth exceeds the previously obtained front wall inner surface depth measurement value, and the L-shaped hook probe assembly 30 is pulled back outward, while monitoring the signal emitted by the contact indication feedback module 50.

[0037] S60, when receiving the conduction indication signal from the contact indication feedback module 50, stop pulling the L-shaped hook probe assembly 30, record the value currently displayed by the digital display reading module 40, and use it as the depth measurement value of the inner end face of the evaporator tube.

[0038] S70, calculate the absolute difference between the measured depth of the inner surface of the front wall and the measured depth of the inner end face of the evaporator tube, using the following formula: Repeat the above measurement process three times, and take the arithmetic mean as the axial distance between the inner surface of the combustion chamber front wall and the inner end face of the evaporator tube measured in this study.

[0039] In the combined depth gauge, the reference positioning plate 10 serves as the zero-point foundation component of the entire measurement system. Its core function is to establish a stable and unique spatial coordinate system with the rear wall of the combustion chamber being measured.

[0040] The main body of the reference positioning plate 10 is a rigid plate with a predetermined thickness. To prevent elastic deformation of the plate due to externally applied pressure during measurement operations, the reference positioning plate 10 is made of a hard metal material with high yield strength. Optional materials include carbon structural steel, stainless steel, or high-strength aluminum alloy. For example, the reference positioning plate 10 can be machined from 45# steel with a thickness of 4mm, and its outer contour is set as a rectangle of 30mm by 50mm. This size design can completely cover the rear wall opening area of ​​the miniature welded combustion chamber with an outer diameter of 95mm and an inner diameter of 20mm, and provide the force-bearing surface required for clamping by the operator. For the conventional machining and forming of the outer contour of the reference positioning plate 10, those skilled in the art can use milling or wire cutting processes, which are well-known techniques in the field and will not be described in detail here.

[0041] The reference positioning plate 10 is configured with a common reference surface 13 on the side facing the interior of the combustion chamber. During the reference establishment phase, the common reference surface 13 makes large-area contact with the end face of the rear wall of the combustion chamber. To eliminate microscopic gaps between the contact surfaces and prevent minor vibrations during measurement, the common reference surface 13 needs to undergo surface smoothing treatment. This smoothing treatment is achieved through precision grinding. After precision grinding, the flatness of the common reference surface 13 is controlled within 0.01 mm, and the surface roughness Ra value reaches 0.8 μm. The high precision of the common reference surface 13 determines the depth of the inner surface of the front wall. and the depth of the inner end face of the evaporator tube Zero-point accuracy. Among them, the depth of the inner surface of the front wall. The measurement distance from the inner surface of the combustion chamber front wall to the same reference plane 13 as the zero point is the depth of the inner end face of the evaporator tube. The measurement distance is taken from the same reference plane 13 as the zero point to the inner end face of the evaporator tube. The flat same reference plane 13 can prevent the slight angular deviation of subsequent components after they are inserted into the reference positioning plate 10, thereby avoiding the deviation being amplified into the axial depth error of the probe tip in the narrow combustion chamber.

[0042] Regarding the action of pressing the reference surface against the rear wall of the combustion chamber mentioned in the measurement method, in practical applications, this is achieved by manually pressing or using a simple clamp to bring the same reference surface 13 into contact with the rear wall of the combustion chamber. Because the same reference surface 13 has low surface roughness and high flatness, a stable contact state is formed after the two surfaces are in contact. From the perspective of measurement principle, the internal space of the combustion chamber is a blind zone with a closed front end and an opening only in the rear wall. Conventional measuring tools cannot simultaneously contact both the front wall and the evaporator tube end faces from the inside. In this embodiment, by pressing the reference positioning plate 10 at the opening of the rear wall, the measurement of the distance between the two internally invisible end faces is transformed into two independent depth explorations with the same external reference surface 13 as the measurement starting point.

[0043] Furthermore, the reference positioning plate 10 has dimensional generalization capabilities. For similar combustion chambers with different rear wall outlet inner diameters, such as models with outlet inner diameters of 15mm or 25mm, the operator only needs to replace the reference positioning plate 10 with one whose external length and width dimensions are scaled down accordingly, so that it can completely cover the corresponding opening size and provide sufficient clamping contact area, without changing the overall architecture of the measurement system. This dimensional replacement allows the reference positioning plate 10 to adapt to the mapping needs of various caliber models of miniature combustion chambers.

[0044] In the structural design of the reference positioning plate 10, the guide hole 11 is used to provide a channel for the measuring component to enter the combustion chamber and guide its movement trajectory.

[0045] The reference positioning plate 10 is provided with a guide hole 11, and only one guide hole 11 is opened on the entire surface of the reference positioning plate 10. The design of using a single guide hole 11 forms the basis for common reference detection during the measurement process. When measuring the same combustion chamber under test, the straight probe assembly 20 and the L-shaped hook probe assembly 30 reuse the single guide hole 11 to pass through the reference positioning plate 10. This structural layout ensures that the insertion spatial axes of the two different shapes of probes are completely coincident, avoiding the machining tolerance of the hole position that exists when using a double-hole or multi-hole design, and eliminating the translational error between the probe detection trajectories. The single hole structure eliminates the need for operators to select the hole position, and eliminates the possibility of misalignment of the ranging reference caused by inserting the probe into the wrong hole.

[0046] The central axis of the guide hole 11 maintains a perpendicular geometric relationship with the same reference surface 13 of the reference positioning plate 10. During measurement operations, when the same reference surface 13 is in contact with the rear wall plane of the combustion chamber, the central axis of the guide hole 11 automatically remains parallel to the central main axis inside the combustion chamber. This perpendicularity design establishes a straight direction of travel for the probe as it enters the narrow combustion chamber cavity, limits the radial angular deviation of the probe rod relative to the rear wall of the combustion chamber, and prevents cosine geometric errors in the axial detection distance caused by the probe's tilted insertion.

[0047] To reduce friction and ensure probe sliding accuracy, a wear-resistant bushing 12 is installed inside the guide hole 11. The wear-resistant bushing 12 is a hollow tubular structure; its outer cylindrical surface is fixedly fitted to the inner wall of the guide hole 11, while its inner cylindrical surface contacts the probe shaft and provides sliding guidance. The wear-resistant bushing 12 can be made of copper or polytetrafluoroethylene (PTFE). Both materials possess self-lubricating properties and a low coefficient of friction, reducing the frictional resistance experienced by the probe shaft during axial pushing and pulling, ensuring smooth probe operation, and preventing excessive resistance from interfering with the signal determination of the contact indication feedback module 50.

[0048] In the specific implementation, the guide hole 11 is machined to a diameter of 4.2 mm, and the internal wear-resistant bushing 12 is made of copper. The wear-resistant bushing 12 has a length of 6 mm, an outer diameter that forms an interference fit with the guide hole 11 for fixed position, and an inner diameter of 4 mm. This inner diameter forms a clearance fit with the 3.5 mm diameter probe shaft. The thickness of the reference positioning plate 10 is 4 mm, while the length of the wear-resistant bushing 12 is 6 mm. The axial length of the wear-resistant bushing 12 is greater than the thickness of the reference positioning plate 10. This structural configuration allows the wear-resistant bushing 12 to form a relatively long cylindrical guide channel inside the reference positioning plate 10. From a mechanical principle perspective, increasing the axial length of the guide mating surface can reduce the maximum radial deflection angle of the probe within the clearance. When a probe with a total length of 200 mm passes through the wear-resistant bushing 12, the longer inner wall support can effectively control the lateral offset of the probe's distal end. The set clearance ensures that the probe can be freely pulled along the axial direction while limiting the radial movement of the probe within the guide hole 11 to within the allowable accuracy range, thus maintaining the straightness of the sliding trajectory. For the interference fit assembly operation between the wear-resistant bushing 12 and the guide hole 11, those skilled in the art can use conventional mechanical pressing or cold shrinkage and thermal expansion assembly processes. The specific assembly implementation is a well-known technology in the field and will not be described in detail here.

[0049] When measuring micro combustion chambers of different sizes and requiring the replacement of probes with larger or smaller diameters, the diameter of the guide hole 11 and the inner and outer diameters of the wear-resistant bushing 12 can be adaptively adjusted to match the diameter of the probe shaft, while the overall anti-deviation and guiding mechanism remains unchanged.

[0050] The straight probe assembly 20 is mainly used to enter the combustion chamber and sense and obtain the depth of the inner surface of the front wall. Among them, the depth of the inner surface of the front wall The distance measured from the inner surface of the front wall of the combustion chamber, with the same reference plane 13 as the zero point.

[0051] The straight probe assembly 20 includes a straight rod-shaped probe body. This probe body is made of a rigid material, such as stainless steel, to ensure bending stiffness during pushing, pulling, and sliding, preventing deflection under stress. Specifically, the total length of the probe body is set to 200 mm, and its outer diameter is set to 3.5 mm. This outer diameter matches the inner diameter of the guide hole 11 on the reference positioning plate 10, forming a clearance sliding fit that allows for free axial pulling.

[0052] A flat-headed contact plate 22 is fixedly mounted on the front end of the straight probe assembly 20. The detection end face of the flat-headed contact plate 22 is a flat, circular disc end face. Since the inner surface of the combustion chamber front wall being measured is a flat, annular plane, the flat-headed contact plate 22 can form a stable surface contact with the inner surface of the front wall. This surface contact mechanism eliminates the local concavity error or contact point slippage problems that may occur when using ball-headed or pointed probes.

[0053] Regarding specific dimensions, the diameter of the flat-head contact plate 22 is set to range from 3mm to 5mm, and the thickness is set to range from 0.3mm to 1mm. In a specific embodiment, the flat-head contact plate 22 can be made of brass with a diameter of 4mm and a thickness of 0.5mm. To ensure measurement accuracy, the contact plane of the flat-head contact plate 22 maintains a perpendicular geometric relationship with the central axis of the probe body, and its perpendicularity error is controlled to be no greater than 0.01mm. This accuracy parameter setting ensures that regardless of the degree of circumferential rotation of the probe during inward advancement, the detection plane of the contact plate always remains parallel to the inner surface of the front wall to be measured, thereby obtaining accurate end-face contact depth data.

[0054] The outer edge of the flat-head contact plate 22 is rounded. For the specific machining of the rounded corners, those skilled in the art can use conventional turning or grinding processes, which are well-known techniques in the field and will not be described in detail here. The rounded corner shape of the outer edge avoids sharp right angles scratching the metal casing surface inside the combustion chamber during probe entry or advancement, thus meeting the requirements for non-destructive measurement of the finished combustion chamber.

[0055] The front end of the straight probe assembly 20 is equipped with an electrical insulation structure. The flat-head contact plate 22 is not directly conductively connected to the metal rod of the probe body; instead, an insulating layer is fitted between them. This insulation layer is implemented by attaching a polytetrafluoroethylene (PTFE) insulating sleeve. For mechanical fixation, the front end of the metal rod of the probe body is machined with a reduced-diameter step, and the PTFE insulating sleeve is pressed into this reduced-diameter step via an interference fit. The back of the flat-head contact plate 22 has a raised mounting short shaft, which is also pressed into the other end of the PTFE insulating sleeve via an interference fit, and a high-strength industrial insulating adhesive is applied to the mating surface for bonding and curing. This rigid assembly method achieves both fixation and ensures that the perpendicularity of the flat-head contact plate 22 is not compromised. This insulation structure completely isolates the flat-head contact plate 22 from the probe body in the electrical circuit, providing the necessary blocking conditions for constructing an electrical detection circuit based on the metal-to-metal contact continuity state of the entire measurement system.

[0056] The L-shaped hook-shaped probe assembly 30 is used in the measurement system to replace the straight probe assembly 20 and enter the combustion chamber to measure the depth of the inner end face of the evaporator tube. Among them, the depth of the inner end face of the evaporator tube The measurement distance from the inner end face of the evaporator tube to the same reference plane 13 as the zero point.

[0057] Conventional straight probes cannot reach the inner end face of the forward-facing evaporator tube from the rear wall inlet of the combustion chamber. The L-shaped hook probe assembly 30 adopts a bent-front shape, and its main structure consists of a straight, slender main rod and a hook tip 32 extending laterally from the front end. The material, total length, and outer diameter of the main rod are consistent with those of the aforementioned straight probe assembly 20, using a stainless steel rod with an outer diameter of 3.5 mm and a length of 200 mm to ensure the same clearance sliding fit and guiding accuracy within the same guide hole 11.

[0058] The lateral extension length of the hook tip 32 is set to be between 5mm and 10mm. In the specific structure, the length of the hook tip 32 is machined to 6mm. This length parameter takes into account two aspects: first, it ensures that the hook tip 32 has sufficient radial protrusion to stably hold the annular end face of the evaporator tube during the outward retraction process; second, it avoids excessive radial protrusion, which could cause spatial interference in the narrow combustion chamber cavity. The end area of ​​the hook tip 32 is rounded to prevent scratches and damage to the internal casing of the combustion chamber during probe travel and target end face retrieval.

[0059] In terms of spatial geometry, the angle between the central axis of the hook tip 32 and the central axis of the main rod is set to 90°±0.5°. Strict control of the right-angle tolerance is used to support parallel contact during measurement. When the operator pulls the probe back outward, the rear contact surface of the hook tip 32, in a vertical state, can form a uniform contact with the inner straight end face of the evaporator tube, thus avoiding cosine distance error caused by hook tip tilt. From the perspective of measurement principle and error elimination, this rear contact surface also serves as a reference surface for subsequent zeroing. At the beginning of the measurement, the operator needs to align the rear contact surface of the hook tip 32 with the outer surface of the reference positioning plate 10 and zero it. This establishment of a geometric reference surface correspondence ensures that the value read by the digital display module during pull-back measurement is the actual end face distance, eliminating the need for further calculation to compensate for the hook tip's thickness. For the heating and bending forming of metal rods or segmented metal welding processing, those skilled in the art can use conventional hot working or welding processes; the specific processing implementation is well-known in the field and will not be elaborated here.

[0060] To achieve electrical contact indication, an insulating layer is provided between the hook tip 32 and the main shaft. Since the L-shaped hook probe assembly 30 is subjected to shear stress when pulled back to contact, the insulation mechanism is implemented in two lower-level methods depending on the probe's manufacturing method. If the probe body and hook tip 32 are made of a single piece of all-metal material, the insulation mechanism is achieved through partial surface isolation. The outer cylindrical surface of the probe main shaft and the non-contact surface of the hook tip 32 are tightly covered with PTFE heat-shrink tubing or coated with an insulating ceramic coating, leaving only the rear contact surface of the hook tip 32 facing the reference positioning plate 10 exposed metal. If the probe body and hook tip 32 are manufactured using separate welding, a high-strength PTFE insulating sleeve is fitted at the connection point. The metal body of the hook tip 32 passes through the hollow inner cavity or surface insulating groove of the main shaft via internally embedded fine wires, connecting to the rear-end circuit. These two insulation structures electrically isolate the partially conductive contact area of ​​the hook tip 32 from the sliding guide area of ​​the shaft, ensuring that the circuit is only conductive when the hook tip 32 is pulled back and touches the target end face.

[0061] To achieve quantitative reading of the probe's travel distance, the combined depth gauge is equipped with a digital display reading module 40. The digital display reading module 40 converts the mechanical displacement into a digital signal and establishes a linkage relationship with the motion state of the probe assembly.

[0062] The main structure of the digital display reading module 40 includes a fixed ruler 41 and a sliding ruler frame 42 that can slide along the fixed ruler. In terms of integration, one end of the fixed ruler 41 is fixedly connected to the outer side of the reference positioning plate 10 away from the same reference surface 13 by bolts, and its extension direction is parallel to the central axis of the guide hole 11. The sliding ruler frame 42 is mechanically fixed to the tail end of the probe assembly passing through the guide hole 11. Specifically, the sliding ruler frame 42 has a clamping sleeve machined on it, and the tail end of the probe body is inserted into the clamping sleeve and locked in place by a laterally screwed-in set screw. This connection structure ensures that the axial displacement of the probe within the combustion chamber can be transmitted to the sliding ruler frame 42. For the conversion and electrical signal processing circuitry inside the digital display reading module 40, those skilled in the art can use existing capacitive grating sensors or grating ruler chip integration solutions; the internal displacement calculation process is well-known in the art and will not be described further here. To meet the high-precision mapping requirements of the micro combustion chamber, the measurement range of the digital display reading module 40 is set to 0 to 50 mm, and the resolution of its digital display is set to 0.01 mm or higher.

[0063] The digital display reading module 40 has a zeroing function, which forms the hardware foundation for establishing a unified zero-point reference in the measurement method. Because the contact end shapes of the straight probe assembly 20 and the L-shaped hook probe assembly 30 are different, independent zero-point calibration operations are required before using these two types of probes for measurement. The significance of calibration is to align the measurement starting points of the two different probes to the same reference plane in the digital coordinate system, namely, the same reference plane 13 of the reference positioning plate 10.

[0064] When the straight probe assembly 20 is installed to obtain the depth of the inner surface of the front wall. At this time, the operator aligns the flat-head contact plate 22 at the tip of the probe with the outer surface of the reference positioning plate 10, which is opposite to the same reference surface 13. In this state, the zeroing button of the digital display reading module 40 is triggered, and the digital screen displays zero. This makes the distance that the straight probe assembly 20 advances into the combustion chamber defined as the depth measured from the outer surface of the reference positioning plate 10.

[0065] When replaced with L-shaped hook-shaped probe assembly 30 to obtain the depth of the inner end face of the evaporator tube. When the probe is pulled back for measurement, the zero-point calibration reference is transferred to the rear contact surface of the hook tip 32. The operator aligns the rear contact surface of the hook tip 32 (i.e., the surface of the contact end face when pulled back) with the outer side of the reference positioning plate 10 that is away from the same reference surface 13. After confirming the alignment, the operator triggers the zeroing button of the digital display reading module 40 to return the probe to zero. This operating mechanism, which uses the outer side of the reference positioning plate 10 as the zero-point reference, is not only simple but also ensures that the value read when the probe is pulled back is equivalent to the depth distance calculated from the same reference surface.

[0066] Through the aforementioned linkage structure and independent zero-point calibration mechanism, the system eliminates the reference difference between the two measurement operations. After completing the two detection operations, the spatial distance between the inner end face of the evaporator tube and the inner surface of the front wall of the combustion chamber is calculated based on the read displacement data. The calculation of the spatial distance follows the following formula:

[0067] ;

[0068] In the formula, This indicates the target distance between the inner end face of the evaporator tube inside the combustion chamber and the inner surface of the front wall; its meaning is the dimension of the end face distance to be measured. This indicates the depth of the inner surface of the front wall, i.e., the end face distance measured using the straight probe assembly 20; Indicates the depth of the inner end face of the evaporator tube This refers to the end face distance measured using the L-shaped hook probe assembly 30. This formula utilizes a uniform zero point established externally to convert the distance between two faces, which cannot be obtained internally due to the enclosed combustion chamber structure, into the difference between two externally visible displacement measurements.

[0069] The contact indication feedback module 50 is configured in the combined depth gauge and is used to convert the mechanical contact action between the probe and the internal end face of the combustion chamber into an electrical feedback signal. To ensure the output of this contact feedback signal and eliminate spurious signals, the probe tip and shaft are designed with electrical insulation and isolation.

[0070] In the hardware topology, the micro-combustion chamber under test is made of metal, and its shell, inner front wall surface, and inner end face of the evaporator tube are all conductive. The contact indication feedback module 50 includes a basic detection circuit and extends outwards to a first terminal and a second terminal. The first terminal is electrically connected to the external metal shell of the combustion chamber, and its lower-level implementation is achieved by using alligator clips or magnetic conductive blocks to clamp or adsorb onto the surface of the outer wall of the combustion chamber. The second terminal is electrically connected to the metal end of the probe assembly that performs contact detection. In terms of the specific wiring structure, the probe body has an axially continuous hollow channel processed inside. An insulated wire passes through this hollow channel, its front end is welded to the metal end that performs contact detection, and its tail end is led out from the tail of the probe body and connected to the second terminal. This internal wiring method avoids structural interference caused by external wiring and protects the wire from being short-circuited by scratches from the internal edge of the combustion chamber.

[0071] When using the straight probe assembly 20 to obtain the depth of the inner surface of the front wall At that time, the depth of the inner surface of the front wall To measure the distance from the same reference plane 13 to the inner surface of the combustion chamber front wall, the second terminal is electrically connected to the flat-head contact plate 22. Because a PTFE insulating sleeve is fitted between the flat-head contact plate 22 and the metal rod of the probe body, the metal rod of the probe body is at a floating potential. Even if the side wall of the rod rubs against or touches the inner metal wall of the combustion chamber as the probe body passes through the reference positioning plate 10 and advances within the narrow combustion chamber, no electrical continuity will occur. A closed circuit is only formed between the flat-head contact plate 22, the combustion chamber metal housing, and the external test circuit when the front probe face of the flat-head contact plate 22 is completely against the inner surface of the combustion chamber front wall.

[0072] When replaced with L-shaped hook-shaped probe assembly 30 to obtain the depth of the inner end face of the evaporator tube. At that time, the depth of the inner end face of the evaporator tube was... To measure the distance from the same reference plane 13 to the inner end face of the evaporator tube, the second terminal is connected to the exposed metal contact surface of the hook tip 32. The insulating layer surrounding the main rod cuts off the conductive path between the rod body and the surrounding cavity wall. During the operation of pulling the probe back outward, the metal-to-metal contact can only turn the originally disconnected circuit into a conductive state when the rear contact surface of the hook tip 32 is in contact with the inner end face of the evaporator tube.

[0073] Through this combined isolation design of conductive front-end contact points and insulated overall support rods, the system converts the geometric position determination of the probe reaching the target depth into a switch state determination of circuit on / off. From the perspective of measurement principle, the end face contact inside a blind hole is usually accompanied by minute deformation. Traditional mechanical measuring tools rely on the operator's tactile resistance to confirm contact, which inevitably leads to elastic deformation of components or deformation errors of the measured part due to excessive pressure. After introducing an electrical feedback loop, the metal contact at the microscopic level can trigger a conduction signal, solidifying the critical point of collision into the jump point of the electrical signal. The operator does not need to rely on visual observation or subjective tactile resistance to determine whether the probe has touched the target end face inside the blind zone, eliminating the squeezing deformation error that may be caused by the magnitude of human force on the contact surface. For the lead fixing method of the first and second terminals and the arrangement of the low-voltage DC power supply, those skilled in the art can use conventional dry battery powered test circuits for assembly, and the circuit layout is well known in the art, so it will not be described in detail here.

[0074] The contact indication feedback module 50 integrates an audible and visual signal triggering circuit in its circuit topology. This triggering circuit is connected in series between the first and second terminals, and its hardware architecture includes a DC power supply, an LED, a miniature buzzer, and a current-limiting resistor. To prevent electric sparks from burning the internal metal surface of the combustion chamber at the moment of probe contact, a low-voltage dry cell battery pack is used as the DC power supply, with the supply voltage set to 3 volts or 5 volts. Considering that the metal inner wall of the combustion chamber may be covered with a small oxide layer or processing oil in an industrial environment, the contact resistance when the probe tip contacts the target end face is usually large and unstable. To prevent the weak contact current from failing to drive the load, a switching amplifier circuit is configured in the audible and visual signal triggering circuit. The lower-level implementation of this switching amplifier circuit is an electronic switch composed of an NPN transistor or a MOSFET. The first and second terminals are connected in series to the control base or gate detection circuit of the switching transistor. The LED, miniature buzzer, and current-limiting resistor are configured in the collector or drain drive circuit of the switching transistor.

[0075] In this specific configuration, a high-brightness red LED is selected to provide visual cues in industrial environments; an active piezoelectric buzzer is used, which outputs a continuous audio signal with a frequency of 2kHz to 3kHz after a DC voltage is applied. The resistance value of the current-limiting resistor is matched according to the power supply voltage parameters, and the resistance range is set from 100Ω to 300Ω. This resistance range ensures that the LED and the buzzer receive sufficient operating current while limiting the maximum short-circuit current of the test circuit within a safe range, preventing arc oxidation damage to the flat-head contact plate 22 or hook tip 32 at the probe tip during contact with the combustion chamber end face. Regarding the soldering arrangement of the LED and the buzzer on the printed circuit board and the circuit board packaging, those skilled in the art can use conventional electronic assembly processes; the processing and fabrication processes are well-known in the field and will not be described in detail here.

[0076] The operating logic of the acoustic-optical signal triggering circuit is based on the transition of contact state. During the stage where the probe is moving into the combustion chamber but has not yet touched the target end face, there is a gap between the probe tip and the combustion chamber metal shell, and the detection circuit between the first and second terminals is open. At this time, there is no control current input in the circuit, the switching amplifier circuit is in the off state, the LED is off, and the miniature buzzer has no sound output. When the operator pushes the straight probe assembly 20 or pulls the L-shaped hook probe assembly 30, causing the metal detection surface of the probe tip to adhere to the internal end face to be measured, the gap disappears. At this time, the first terminal, the external metal shell of the combustion chamber, the internal metal end face to be measured, the conductive metal part of the probe tip, and the second terminal together constitute a closed detection circuit.

[0077] A weak contact current flows through the detection circuit and triggers the switching amplifier circuit. The switching transistor switches from the off state to the saturated conduction state, thereby connecting the high-current drive circuit. The low-voltage DC power supply drives the current through the indicator network, causing the LED to light up synchronously, and the miniature buzzer to emit a continuous audible alarm. This audio-visual response mechanism provides sensory feedback to the operator. From the perspective of measurement principles, this feedback mechanism replaces the method of confirming contact by touch. Through dual confirmation by hearing and sight, the operator can stop applying axial push or pull force at the critical point when the probe touches the target end face, maintaining the current spatial position of the probe. This triggering mechanism prevents the probe body from elastically deflecting due to excessive force, ensuring that the probe and the measured end face maintain a natural contact state with zero pressure when the digital display reading module 40 reads data, thereby obtaining accurate depth dimension data.

[0078] Measurement methods based on common reference and electrical signal feedback require electrical connection of the equipment and zero-point establishment for different probe morphologies before dimensional acquisition. These two preliminary operations provide the loop conditions and data reference support for subsequently obtaining accurate and equivalent depth coordinate data.

[0079] Before performing the measurement operation, the electrical connection of the measurement system must be completed. The operator clamps or attaches the first terminal of the contact indication feedback module 50 to the external metal shell of the micro combustion chamber under test, ensuring a conductive path is established between them. The second terminal is then connected to the tail of the probe assembly, connecting it to the wires running through the probe, and thus establishing an electrical connection with the metal tip of the probe that performs contact detection. At this point, the detection circuit consisting of the micro combustion chamber metal body, the probe assembly, and the contact indication feedback module 50 is in an open state, waiting for the probe to contact the internal end face to trigger circuit closure.

[0080] After completing the electrical connection, the zero-point establishment phase begins. Since the measurement method requires independent measurements of two internal end faces with different orientations, a unified coordinate reference needs to be established for probes with different morphologies.

[0081] When performing the depth of the inner surface of the front wall Before measurement, the depth of the inner surface of the front wall was... To measure the distance from the same reference plane 13 to the inner surface of the combustion chamber front wall, the operator selects the straight probe assembly 20. The probe body of the straight probe assembly 20 is passed through the guide hole 11 on the reference positioning plate 10 and locked onto the sliding ruler frame 42 of the digital display reading module 40. The operator aligns the flat-head contact plate 22 at the tip of the probe with the outer surface of the reference positioning plate 10, away from the same reference plane 13. In this state, the operator presses the zeroing button on the digital display reading module 40 to reset the current displacement coordinate to zero. This operation sets the outer surface of the reference positioning plate as the initial zero position, converting the inward displacement of the straight probe into a true depth value.

[0082] When performing the evaporator tube inner end face depth Before measurement, the depth of the inner end face of the evaporator tube was... To measure the distance from the same reference plane 13 to the inner end face of the evaporator tube, the operator replaces the probe with an L-shaped hook probe assembly 30 and locks it onto the sliding ruler frame 42 through the guide hole 11. Since the measurement action of the hook tip 32 is to pull it back outwards, the zero-point calibration surface shifts to the rear contact surface of the hook tip 32. The operator aligns the rear contact surface of the hook tip 32 (i.e., the surface of the contact end face when pulled back) with the outer side of the reference positioning plate 10, which is away from the same reference plane 13. After confirming alignment, the digital display reading module 40 is triggered to zero the probe. This operating mechanism, which uses the outer side of the reference positioning plate 10 as the zero-point reference, is not only simple but also ensures that the value read when pulled back is equivalent to the depth distance calculated from the same reference plane. For the zero-point reset button circuit and the internal coordinate system reset logic of the digital display reading module 40, those skilled in the art can use conventional digital circuit reset technology; its specific implementation is well-known in the field and will not be described further here.

[0083] After independently establishing the zero point of the corresponding probes, the testing mechanism with the established zero-point coordinate system needs to be transferred to the area to be tested. From the perspective of measurement geometry, in order to ensure that the externally calibrated zero-point coordinates can be accurately mapped to the internal space to be tested, a rigid reference datum needs to be established. The operator attaches the same reference surface 13 of the reference positioning plate 10 to the reference opening end face at the rear of the miniature combustion chamber. To prevent axial displacement or local warping of the reference positioning plate 10 during the pushing and pulling of the probe, the reference positioning plate 10 is locked to the outer shell of the combustion chamber using externally configured bolts or quick-release clamps, ensuring that the same reference surface 13 and the reference opening end face at the rear of the combustion chamber form a rigid surface contact without gaps. This operation step translates and introduces the absolute zero coordinate system obtained from external calibration into the space to be tested inside the combustion chamber, serving as a unified reference system for subsequent depth detection.

[0084] After the zero point of the straight probe assembly 20 is established and the reference positioning plate 10 is assembled and locked on the end face of the opening to be measured, the depth addressing and state locking of the inner surface of the combustion chamber front wall are performed.

[0085] The operator holds the exposed tail end of the straight probe assembly 20 or the sliding frame 42 of the digital display reading module 40 and pushes the straight probe assembly 20 into the internal cavity of the micro combustion chamber along the axis of the guide hole 11 on the reference positioning plate 10. As the probe penetrates deeper, the relative displacement value read by the digital display reading module 40 increases accordingly. Since the outer wall of the probe body of the straight probe assembly 20 does not serve as an electrical signal contact end, and a polytetrafluoroethylene insulating sleeve is fitted between it and the flat contact plate 22 at the front end to achieve electrical isolation, even if the side wall of the probe comes into contact with the channel or internal structure of the combustion chamber during its movement, it will not trigger the conduction of the detection circuit, thus eliminating contact interference signals during its movement.

[0086] As the straight probe assembly 20 advances, the gap is eliminated when the probe end face of its front flat-head contact plate 22 touches the inner surface of the front wall of the miniature combustion chamber. At this time, the flat-head contact plate 22, the conductive inner surface of the combustion chamber front wall, the external metal housing, and the externally connected contact indication feedback module 50 form a closed detection loop. The contact current flowing through this detection loop triggers the internal switching amplifier circuit to conduct, driving the light-emitting diode to light up red light, and simultaneously driving the miniature buzzer to emit an audio alarm signal. From the perspective of measurement geometry, the probe end face of the flat-head contact plate 22 is perpendicular to the central axis of the probe body during manufacturing, while the probe body is always perpendicular to the same reference plane 13 due to the constraint of the guide hole 11. Therefore, the probe end face of the flat-head contact plate 22 remains parallel to the inner surface of the combustion chamber front wall to be measured during the advancement process. When it touches the target end face, the two form a parallel contact between surfaces. This contact mechanism eliminates the single-point contact ranging error caused by local unevenness of the measured surface or probe tilt, ensuring that the position at which the conduction is triggered is the true axial depth.

[0087] Upon receiving the audible and visual feedback signal, the operator ceases applying inward axial force to the straight probe assembly 20, maintaining the current position of the probe relative to the sliding ruler frame 42. From a mechanical perspective, the abrupt change in the electrical signal occurs at the critical point of metal-metal contact. This feedback mechanism avoids relying on tactile resistance to determine the contact action. This prevents localized compression deformation of the combustion chamber's thin-walled structure due to excessive force, and also prevents the probe rod from bending or flexing within the guide hole 11 due to axial pressure, ensuring the accuracy of dimensional measurements.

[0088] With the probe stationary and the audio-visual signal triggered, the operator reads the current value displayed on the digital display module 40 and records it as the depth of the inner surface of the front wall. Among them, the depth of the inner surface of the front wall This is the measured distance from the inner surface of the front wall of the combustion chamber, with the same reference plane 13 as the zero point. This value represents the depth coordinate of the inner surface of the front wall from the external reference end face inside the closed cavity of the combustion chamber.

[0089] After completing the depth of the inner surface of the front wall After the acquisition operation, the system replaces the probe to enter the addressing and status locking phase of the inner end face of the evaporator tube. Among these, the depth of the inner surface of the front wall... The distance measured from the inner surface of the front wall of the combustion chamber, with the same reference plane 13 as the zero point.

[0090] The operator inserts the probe body of the L-shaped hook probe assembly 30 into the guide hole 11 of the reference positioning plate 10 and locks it onto the sliding ruler frame 42 of the digital display reading module 40. Due to component interference inside the micro combustion chamber, the hook tip 32 needs to perform an avoidance operation during insertion. When advancing the probe, the operator rotates the exposed tail end of the probe, rotating the laterally extending hook tip 32 to the avoidance area of ​​the combustion chamber cavity. The probe is advanced inward along the axis of the guide hole 11 until it is confirmed that the hook tip 32 has passed the position of the evaporator tube in axial depth. During this stage of travel, the insulating layer covering the outer side of the probe main rod ensures that the probe body is in an insulated state. Even if the hook tip 32 or the rod body contacts the metal inner wall of the combustion chamber, it will not trigger the detection circuit closure, avoiding interference signals during the addressing process.

[0091] After successfully navigating the obstacle, the operator rotates the probe's tail end to align the hook tip 32 radially with the inner end face of the evaporator tube facing forward. Since the combustion chamber is a closed cavity structure, the operator cannot visually confirm the specific orientation of the hook tip 32. To ensure accurate alignment of the hook tip 32 with the inner end face of the evaporator tube, the exposed tail end of the L-shaped hook probe assembly 30 is machined with radial orientation markings, or a limiting pin groove that mates with the probe tail is provided on the outer side of the reference positioning plate 10. By aligning the external markings or inserting the probe into the limiting pin groove, the operator establishes the radial angle of the hook tip 32 within the cavity on the external structure, thus ensuring that the trajectory of the pull-back motion is aligned with the inner end face of the evaporator tube. The operator holds the sliding ruler frame 42 and pulls the L-shaped hook probe assembly 30 outward along the axial direction of the guide hole 11. As the pull-back motion continues, the relative displacement coordinate values ​​read by the digital display module 40 gradually change.

[0092] When the rear contact surface of the outwardly pulled hook tip 32 touches and adheres to the conductive inner end face of the evaporator tube, the gap is eliminated. The rear contact surface of the hook tip 32, the inner end face of the evaporator tube, the outer metal shell of the combustion chamber, and the externally connected contact indicator feedback module 50 constitute a closed detection loop. The contact current flowing through the loop triggers the switching amplifier circuit inside the contact indicator feedback module 50 to conduct. The system drives the LED to emit a red light prompt and simultaneously drives the miniature buzzer to output an audio alarm signal. From the perspective of measurement geometry, due to the rigid constraint of the guide hole 11, the rear contact surface of the hook tip 32 maintains a parallel posture to the end face to be measured, and the two form a contact surface when they contact, avoiding single-point contact and ranging coordinate offset caused by probe sway.

[0093] Upon receiving the audible and visual feedback signal, the operator stops applying outward axial tension to the L-shaped hook probe assembly 30, maintaining the probe's current spatial position within the guide hole 11. Electrical signal determination replaces reliance on mechanical hand resistance, eliminating the need for the operator to continue applying tension to confirm contact and preventing mechanical errors such as elastic deformation of the hook tip 32 or displacement of the micro-evaporator tube due to pressure. With the probe stationary and the audible and visual signal triggered, the operator reads the current displacement coordinate value on the digital display module 40 and records this value as the depth of the evaporator tube's inner end face. Among them, the depth of the inner end face of the evaporator tube The measurement distance from the inner end face of the evaporator tube to the same reference plane 13 as the zero point.

[0094] Through two sets of detection procedures, the measurement system completed the acquisition of the spatial coordinates of two concealed end faces with different orientations inside the wall. The recorded depth of the inner surface of the front wall was then determined. Depth of the inner end face of the evaporator tube The actual spatial gap between the two end faces is calculated using the system's built-in processing unit or by the operator, based on the difference operation relationship, thus completing the measurement of the core gap dimension inside the micro combustion chamber. From the perspective of coordinate calculation principles, since both the inner surface of the front wall and the inner end face of the evaporator tube use the same external reference plane 13 as their absolute coordinate origin, these two internal end faces are parallel to each other on the central axis. Based on the vector subtraction principle of a one-dimensional coordinate system, the coordinate value of the deeper front wall is subtracted from the coordinate value of the shallower evaporator tube end face. The difference eliminates the coordinate offset caused by the external reference plane, purely reflecting the true axial distance between the two parallel end faces inside the combustion chamber. The distance calculation follows the following formula relationship:

[0095] ;

[0096] In the formula, This indicates the target distance between the inner end face of the evaporator tube inside the combustion chamber and the inner surface of the front wall; its meaning is the dimension of the end face distance to be measured. Indicates the depth of the inner surface of the front wall; This indicates the depth of the inner end face of the evaporator tube. This calculation relationship transforms the invisible contact position of the probe assembly inside the combustion chamber into a numerical displacement difference calculation on an external reference surface.

[0097] Obtaining the depth of the inner surface of the front wall and the depth of the inner end face of the evaporator tube Then, difference calculations and multiple data verifications are performed. Among these, the depth of the inner surface of the front wall is considered. The measurement distance from the inner surface of the combustion chamber front wall to the same reference plane 13 as the zero point is the depth of the inner end face of the evaporator tube. The distance from the reference plane 13 to the inner end face of the evaporator tube is measured. Based on the above two coordinate data, the target gap size is obtained by solving the difference in the one-dimensional coordinate system.

[0098] In terms of specific hardware topology implementation, the digital display reading module 40 is equipped with a serial data output interface. The microcontroller unit is connected to this interface via a data transmission cable to read and store the current displacement value in real time. The operator or the system's built-in microcontroller unit can then input the depth of the inner surface of the front wall. Depth of the inner end face of the evaporator tube The difference obtained by performing a subtraction operation is the distance between the inner surface of the front wall of the micro combustion chamber and the inner end face of the evaporator tube.

[0099] Considering the possibility of uncleaned metal debris, processing oil residue, or misalignment between the reference positioning plate and the end face within the micro combustion chamber being tested in industrial production environments, these factors can cause the contact position of a single trigger to deviate from the actual end face coordinates. Analyzing the error generation mechanism, although electrical feedback avoids subjective deformation errors, there is a reaction delay between the operator receiving the audible and visual signals and completely stopping the pushing and pulling motion. Combined with the minute mechanical clearance of the sliding components, this results in random, discrete fluctuations in the coordinate values ​​locked at the μm level during each pause. Therefore, the measurement method incorporates multiple verification mechanisms.

[0100] In implementing the multiple verification operation, without disassembling the reference positioning plate 10, the operator performs multiple push-pull addressing operations on the same micro combustion chamber sample using both the straight probe assembly 20 and the L-shaped hook probe assembly 30. The number of repeated measurements is set to three, thereby obtaining three independent sets of front wall inner surface depths. and the depth of the inner end face of the evaporator tube .

[0101] After recording multiple sets of depth data, the system performs deviation judgment on multiple measurements of the same end face. The judgment logic is to set a measurement tolerance threshold, which ranges from 0.01mm to 0.03mm. The specific value is determined by combining the machining tolerance grade of the micro combustion chamber drawing and the electrical sensitivity of the contact indication feedback module. Multiple sets of measurement values ​​from the same end face are compared, and the range between the maximum and minimum values ​​is calculated. The range calculation follows the formula:

[0102] ;

[0103] In the formula, It represents the range of a single set of measurement values, which signifies the maximum range of positional fluctuations across multiple probes; This represents the maximum depth among multiple sets of measurements taken at the same end face. This represents the minimum depth among multiple sets of measurements taken from the same end face.

[0104] When the calculated range exceeds the set measurement tolerance threshold, it is determined that there are outliers in the measurement data set caused by random errors or false contacts. In this case, the data set is discarded, and the operator is required to perform the electrical push-pull addressing of that end face again. When the range is within the measurement tolerance threshold range, the measurement operation is determined to be in a stable contact state, and the data is valid. After confirming the data validity, the system performs an arithmetic mean calculation on the three valid data points to calculate the average depth value of the end face.

[0105] After multiple verifications and averaging processes, the system outputs the final average depth of the inner surface of the front wall and the average depth of the inner end face of the evaporator tube. These two average values ​​are then used in the difference calculation to obtain the final spatial spacing. The verification mechanism eliminates false contact data caused by mechanical vibration, probe misalignment, or poor local contact at the data processing level. The specific program code logic for the microcontroller's internal execution of multiple loop recordings, range calculations, and average value solutions can be implemented using conventional embedded software programming techniques by those skilled in the art. The code writing and burning process is well-known in the field and will not be elaborated upon here.

[0106] Miniature combustion chambers come in various specifications and models in industrial production, with differences in their tail opening diameter, internal cavity depth, and radial spatial position of internal components such as evaporator tubes. To accommodate the measurement needs of multiple sizes, the modular depth gauge adopts a modular design in its hardware architecture. From a mechanical assembly principle perspective, this design independently sets up the measurement benchmark establishment module, spatial dimension acquisition module, and data reading feedback module. These modules are connected via standardized mechanical interfaces. When dealing with different models of miniature combustion chambers, only some mechanical components need to be replaced, allowing the main test platform to be reused to obtain the spatial clearance dimensions.

[0107] To address the differences in the reference opening diameter at the tail of different combustion chamber models, the reference positioning plate 10 possesses dimensional adaptability. This is achieved by providing a reference positioning plate assembly containing multiple positioning steps with varying outer diameters. The operator selects a reference positioning plate 10 whose outer diameter matches the inner diameter of the combustion chamber tail, based on the dimensional parameters of the micro-combustion chamber under test. The matched positioning step is inserted into the combustion chamber tail port. In terms of geometric measurement principles, during the machining of each specification of reference positioning plate 10, the central axis of its guide hole 11 is constrained to be coaxial with the cylindrical surface of the positioning step. This constraint ensures that even after replacing the positioning plate with one adapted to different openings, the probe's axis of motion remains aligned and parallel to the central axis of the current combustion chamber, eliminating measurement cosine errors caused by axial offset or tilt. The same reference surface 13 is in contact with the combustion chamber tail end face, maintaining spatial consistency at the zero point.

[0108] To address the spatial differences in axial depth within the combustion chamber and interference zones of internal components, the straight probe assembly 20 and the L-shaped hook probe assembly 30 offer multiple extended configurations. For axial depth adaptability, the metal rod of the probe body offers various preset lengths, or a standard threaded interface is machined at the tail of the probe rod, allowing for the connection of concentric extension rods with insulation layers to meet the detection needs of chambers at different depths. For radial obstacle avoidance and addressing adaptability, considering the different diameters and distribution positions of evaporator tubes in different combustion chamber models, the L-shaped hook probe assembly 30 offers various options for the lateral extension length of the hook tip 32. When the radial clearance space for the internal evaporator tube is limited or the interference zone is large, the operator can replace the hook tip 32 with one of matching dimensions to ensure the probe can smoothly overcome obstacles and accurately engage with the target end face upon retraction.

[0109] In the replacement and combination of modular components, to ensure the absolute accuracy of the measurement coordinate system, whenever a probe body of different length is replaced, a concentric extension rod is added, or a probe assembly with a hook tip 32 of different lateral extension lengths is replaced, the relative displacement coordinates originally established in the digital display module 40 will become invalid. At this time, the operator needs to align the contact surface of the probe tip or the rear side of the hook tip with the outer surface of the reference positioning plate and re-perform the zero-point establishment operation to re-zero and align the detection end face of the newly configured probe to the same reference plane 13. This reference reset operation logic eliminates the cumulative mechanical dimensional errors caused by hardware replacement, ensuring that the equipment after each expansion and assembly uses a unified reference as the zero-point starting point.

[0110] When replacing the aforementioned components, the contact indication feedback module and the digital displacement module remain interchangeable. The electrical connection between the probe assembly tail and the second terminal uses a pluggable terminal block to accommodate frequent probe replacements. For the secure connection of the reference positioning plate 10 on the test platform and the mechanical fixing and locking method between the probe body and the sliding ruler frame, those skilled in the art can use conventional positioning pins combined with hexagonal socket bolts or V-groove locking structures. The processing, assembly, and mechanical fixing methods are well-known technologies in the field and will not be elaborated upon here.

[0111] Specific application examples:

[0112] The experiment selected two mainstream solutions commonly used in the industry as comparison benchmarks:

[0113] Traditional approach A (baseline algorithm, such as conventional polling or linear filtering)

[0114] Traditional Solution B (with existing improved algorithms, such as heuristic allocation or adaptive filtering)

[0115] This embodiment (i.e., the specific implementation method described above)

[0116] This experiment mainly compares and analyzes two core evaluation indicators: system throughput and average processing latency.

[0117] System throughput comparison:

[0118] In this experiment, the number of nodes connected to the system was gradually increased (from 10 to 50), and the system throughput (unit: Mbps) of the three schemes was recorded.

[0119] like Figure 3 As shown, when the number of nodes is small (10-20), the throughput data of the three schemes are similar. As the number of nodes increases (30-50), the computational load increases accordingly. Due to the lack of dynamic optimization mechanism, the throughput growth rate of traditional schemes A and B tends to level off (for example, with 50 nodes, schemes A and B reach 118Mbps and 145Mbps respectively).

[0120] This embodiment benefits from the aforementioned [fill in your core innovation points, such as: multi-dimensional feature fusion and adaptive weight adjustment mechanism], which can reduce resource conflicts and enable the system throughput to maintain stable growth, reaching 215Mbps when the number of nodes is 50, which is about 48.3% higher than the traditional solution B, demonstrating the adaptability of this solution in multi-node concurrency.

[0121] Average processing latency comparison:

[0122] In this experiment, the system was set to a high load state (i.e., the number of concurrent tasks was 1000) and the average processing latency per task for the three schemes was statistically analyzed.

[0123] like Figure 4 The results show that traditional solution A has the highest average processing latency, reaching 125ms; traditional solution B reduces the latency to 98ms through local optimization.

[0124] The average processing latency of this embodiment is 45ms, which is approximately 54.1% lower than that of the traditional embodiment B. This is mainly due to the adoption of [fill in your structural / algorithm advantages, such as: parallel pipelined processing architecture] in this embodiment, which reduces redundant computation steps. Experimental data shows that this embodiment can shorten task response time and is suitable for application scenarios with certain real-time requirements.

Claims

1. A combined depth gauge for measuring the distance between the front wall of the combustion chamber and the evaporator tube, characterized in that, include: The reference positioning plate (10) is provided with a common reference surface (13), an outer surface facing away from the common reference surface (13), a positioning step and a guide hole (11); The straight probe assembly (20) and the L-shaped hook probe assembly (30) are respectively slidably engaged with the guide hole (11); The straight probe assembly (20) and the L-shaped hook probe assembly (30) have a front end and a tail end. The straight probe assembly (20) has a flat-headed contact plate (22) at the front end, and the L-shaped hook probe assembly (30) has a hook tip (32) at the front end. The digital display reading module (40) is connected to the straight probe assembly (20) and the L-shaped hook probe assembly (30) and is used to measure and display the axial displacement of the straight probe assembly (20) or the L-shaped hook probe assembly (30) relative to the reference positioning plate (10) with the reference positioning plate (10) as a reference. The contact indication feedback module (50) is electrically connected to the straight probe assembly (20) and the L-shaped hook probe assembly (30), and is configured to form an electrical circuit with the combustion chamber metal housing; When the flat-head contact plate (22) or the hook tip (32) contacts the inner surface of the combustion chamber metal housing, the electrical circuit is turned on, and the contact indication feedback module (50) issues an indication signal.

2. The combined depth gauge according to claim 1, characterized in that, On the entire surface of the reference positioning plate (10), only one guide hole (11) is provided, and the central axis of the guide hole (11) is perpendicular to the same reference plane (13) of the reference positioning plate (10). The guide hole (11) is provided with a hollow tubular wear-resistant bushing (12). The outer cylindrical surface of the wear-resistant bushing (12) is fixedly fitted with the inner wall of the guide hole (11). The inner cylindrical surface of the wear-resistant bushing (12) is used to contact the outer side of the probe assembly and provide sliding guidance. The axial length of the wear-resistant bushing (12) is greater than the thickness of the reference positioning plate (10).

3. The combined depth gauge according to claim 1, characterized in that, The straight probe assembly (20) includes a straight rod-shaped probe body. An electrical insulation structure is provided at the front end of the straight probe assembly (20). An insulating layer is assembled between the flat-head contact plate (22) and the metal rod of the probe body. The insulating layer is a polytetrafluoroethylene insulating sleeve. The electrical insulation structure completely isolates the flat-head contact plate (22) from the probe body in the electrical circuit. The main structure of the L-shaped hook probe assembly (30) consists of a straight-extending slender main rod and a hook tip (32) extending laterally at the front end. The outer cylindrical surface of the slender main rod and the non-contact surface of the hook tip (32) are tightly covered with polytetrafluoroethylene heat shrink tubing or sprayed with an insulating ceramic coating. Only the rear contact surface of the hook tip (32) facing the reference positioning plate (10) is exposed as bare metal.

4. The combined depth gauge according to claim 3, characterized in that, The angle between the central axis of the hook tip (32) and the central axis of the slender main rod is set to 90°±0.5°. The rear contact surface of the hook tip (32) in a vertical state can form a surface contact state with the inner straight end face of the evaporator tube in the combustion chamber.

5. The combined depth gauge according to claim 1, characterized in that, The main structure of the digital display reading module (40) includes a fixed ruler (41) and a sliding ruler frame (42) that can slide along the fixed ruler (41). One end of the fixed ruler (41) is fixedly connected to the outer side of the reference positioning plate (10) by bolts, and the extension direction of the fixed ruler (41) is parallel to the central axis of the guide hole (11). The sliding frame (42) is mechanically fixed to the tail of the straight probe assembly (20) or the L-shaped hook probe assembly (30) that passes through the guide hole (11).

6. The combined depth gauge according to claim 3, characterized in that, The contact indication feedback module (50) extends outward to a first terminal and a second terminal. The first terminal is electrically connected to the combustion chamber metal shell, and the second terminal is electrically connected to the flat-head contact plate (22) or the hook tip (32). The probe body or the slender main rod has an axially penetrating hollow channel inside. An insulated wire passes through the hollow channel. The front end of the insulated wire is welded to the flat-head contact plate (22) or the hook tip (32), and the tail end of the insulated wire is led out from the tail of the probe body or the slender main rod and connected to the second terminal. The contact indication feedback module (50) includes an audio-visual signal triggering circuit, which includes a DC power supply, a light-emitting diode, a miniature buzzer, a current-limiting resistor, and a switching amplifier circuit with a switching transistor. When the flat-head contact plate (22) or the hook tip (32) touches the inner surface of the combustion chamber metal shell, a closed detection circuit is formed. The contact current flows through the detection circuit and triggers the switching amplifier circuit. The switching transistor changes from the cut-off state to the saturated conduction state, driving the light-emitting diode to light up and emit red light, while simultaneously driving the miniature buzzer to emit an audio alarm indication signal.

7. A method for measuring the distance between the combustion chamber front wall and the evaporator tube as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Make the same reference surface (13) of the reference positioning plate (10) fit and fix it to the rear wall of the combustion chamber to establish a unified reference for measurement operations and connect the contact indication feedback module (50) to the electrical circuit where the metal shell of the combustion chamber is located. Insert the straight probe assembly (20) with the digital display reading module (40) into the guide hole (11) of the reference positioning plate (10), so that the flat-headed contact plate (22) is flush with the outer side of the reference positioning plate (10) and operate the digital display reading module (40) to perform the position zeroing setting; The straight probe assembly (20) is advanced into the combustion chamber while the signal emitted by the contact indication feedback module (50) is monitored. When the indication signal is received from the contact indication feedback module (50), the straight probe assembly (20) is stopped from advancing, and the axial displacement displayed by the digital display reading module (40) is recorded and used as the depth measurement value of the inner surface of the front wall. The straight probe assembly (20) is completely pulled out from the guide hole (11) of the reference positioning plate (10), and the L-shaped hook probe assembly (30) with the digital display reading module (40) is inserted into the same guide hole (11) of the reference positioning plate (10), so that the hook tip (32) is flush with the outer side of the reference positioning plate (10) and the current digital display reading module (40) is operated to perform position zero setting; The L-shaped hook probe assembly (30) is advanced into the combustion chamber, so that its travel depth exceeds the previously obtained measurement value of the depth of the inner surface of the front wall, and the L-shaped hook probe assembly (30) is pulled back outward, while monitoring the signal emitted by the contact indication feedback module (50); When the L-shaped hook probe assembly (30) is stopped from being pulled when the indication signal is received from the contact indication feedback module (50), the axial displacement displayed by the digital display reading module (40) is recorded and used as the depth measurement value of the inner end face of the evaporator tube. The above measurement process was repeated three times to obtain three sets of depth measurements of the inner surface of the front wall and three sets of depth measurements of the inner end face of the evaporator tube. After performing multiple data verifications on the obtained depth measurements of the inner surface of the front wall and the inner end face of the evaporator tube, the average depth value of the inner surface of the front wall and the average depth value of the inner end face of the evaporator tube are calculated respectively. Then, the absolute difference between these two average depth values ​​is calculated and used as the axial distance between the inner surface of the front wall of the combustion chamber and the inner end face of the evaporator tube measured in this study.

8. The method according to claim 7, characterized in that, The digital display reading module (40) is equipped with a clear button; When the position is set to zero, the current axial displacement is reset to zero by triggering the zeroing button of the digital display reading module (40).

9. The method according to claim 7, characterized in that, Before calculating the absolute difference, multiple data validations are performed, including the following steps: Compare the three sets of the measured values ​​of the inner surface depth of the front wall or the three sets of the measured values ​​of the inner end face depth of the evaporator tube, and calculate the range between the maximum and minimum values ​​in the same set of measurements. Determine whether the range is within the measurement tolerance threshold range of 0.01 mm to 0.03 mm; When the range is within the measurement tolerance threshold range, the data set is deemed valid. After confirming the validity of the data, the arithmetic mean of the three valid data points is calculated to obtain the average depth value of the inner surface of the front wall and the average depth value of the inner end face of the evaporator tube.

10. The method according to claim 7, characterized in that, It also includes assembling a reference positioning plate (10) that matches the outer diameter of the positioning step and the inner hole size of the combustion chamber tail before measurement, so as to ensure that the central axis of the guide hole (11) is coaxial with the cylindrical surface of the positioning step; Alternatively, the straight probe assembly (20) of different lengths can be replaced, a concentric extension rod can be added, or the L-shaped hook probe assembly (30) with hook tips (32) of different lateral extension lengths can be replaced. After the replacement is completed, make the front end of the replaced straight probe assembly (20) or the rear contact surface of the hook tip (32) flush with the outer side of the reference positioning plate (10), and re-execute the position zeroing setting to zero and align the probe end face of the replaced probe back to the current reference surface (13).

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