Oxygen sensor and probe subassembly thereof

Abstract

The utility model relates to an oxygen sensor and a probe subassembly thereof, the probe subassembly comprises a zirconium element, a shell, a ceramic piece, a sealing material and a lower shield, the zirconium element is a long strip with a rectangular cross section; the shell is in a U-shaped barrel shape and comprises an upper opening, a shell bottom and a cylindrical hollow part, the outer surface of the shell comprises an upper opening edge, an upper fastening barrel, a shaft shoulder, a lower connecting threaded barrel and a lower shield connecting flange which are sequentially connected along the central axis, and the shell bottom comprises a rectangular through hole along the central axis of the shell; the upper fastening cylinder is used for being connected with an upper shield of the oxygen sensor in a tight fit manner; the lower shield connecting flange is used for connecting a lower shield; the lower connecting threaded cylinder is provided with threads and used for being connected with connector threads of a vehicle exhaust pipe. The lower part of the cylindrical hollow part is filled with the sealing material; the ceramic piece is located on the upper portion of the cylindrical hollow part and pressed on the sealing material, and the ceramic piece is fixed by riveting the edge of the upper opening. The structure is simplified, internal leakage of the oxygen sensor can be effectively controlled, the sealing performance is high, and powder is not prone to falling off.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of automobile parts production and manufacturing, especially to oxygen sensor. BACKGROUND

[0002] Oxygen sensor is an essential automobile part in vehicle manufacturing industry. It is used to detect the oxygen content in the exhaust pipe of automobile engine, so as to determine the real-time air-fuel ratio state of the engine. According to the different oxygen concentration, the sensor will output different voltage signals to the engine electronic control module (ECM) as an important basis for system closed-loop fuel correction compensation control. Due to the application of oxygen sensor, the engine can work in the ideal air-fuel ratio state under most working conditions, thereby obtaining good emission characteristics and fuel economy.

[0003] Oxygen sensor adopts a flat structure multilayer ceramic element as a basic element, and the zirconia layer is the core element. The working principle of the zirconia element is equivalent to a simple solid primary battery. According to the principle of electrochemistry, there will be a potential difference between the two electrodes due to the difference in oxygen ion concentration. The outer electrode is exposed to the exhaust gas, and the oxygen ion concentration will change according to the actual working condition, while the inner electrode is the reference air, and the oxygen ion concentration is constant. When the engine air-fuel ratio is dilute, the oxygen ion concentration in the exhaust gas is relatively high, the oxygen ion concentration difference between the inner and outer electrodes is small, that is, the potential difference is small, and the output voltage signal of the oxygen sensor is close to 0V; on the contrary, when the air-fuel ratio is thick, the oxygen ion concentration in the exhaust gas is relatively low, the oxygen ion concentration difference between the inner and outer electrodes is large, that is, the potential difference is large, and the output voltage of the sensor is close to 1V.

[0004] The oxygen sensor on the market, whether it is a switch type or a wide range type, generally uses talc powder and ceramic insulator, which needs to be sealed by one or more times of pressing. The sealing quality determines whether the sensor signal is accurate or not. The existing oxygen sensor is difficult to control the internal leakage, has poor sealing performance, is easy to fall off the powder, and causes pollution. On the other hand, its structure is complex, the cost is high, and it is extremely unfavorable for product production and market promotion. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a probe subassembly and an oxygen sensor adopting the probe subassembly to simplify the structure and effectively control the internal leakage of the oxygen sensor.

[0006] In order to achieve the above object, the utility model provides a probe subassembly for oxygen sensor, its characterized in be including zirconium element, shell, ceramic piece, sealing material and lower shield, wherein, the zirconium element is the long strip of the cross section of rectangle, is set to pass through the shell and be located the ceramic piece and sealing material in the shell along the middle axis of shell, the shell is U type cylinder shell, including upper opening, shell bottom and along the cylindrical hollow portion of upper opening and extend to shell bottom, the outer surface of shell includes the upper opening edge, upper fastening cylinder, shaft shoulder, lower connection thread cylinder, lower shield connection flange that connect in proper order from the upper opening, wherein, the shell bottom has the through hole of the cross section of rectangle, and this through hole is located the middle axis of shell for the zirconium element passes through, the upper fastening cylinder is used to connect the upper shield of oxygen sensor through tight fit, the lower shield connection flange is used to connect the lower shield, the outer surface of lower connection thread cylinder has the thread for connecting the interface thread of vehicle exhaust pipe, the sealing material fills the lower part of cylindrical hollow portion, and the surface of zirconium element and cylindrical hollow portion is in close contact, the sealing material includes 30 to 50 percent talcum powder, 30 to 50 percent glass powder and 10 to 15 percent magnesium stearate, the ceramic piece is located the upper part of cylindrical hollow portion, and is pressed on the sealing material, and the ceramic piece is fixed through riveting the upper opening edge.

[0007] As a preferred mode, the surface of the zirconium element is printed with a heating circuit, which includes a heating resistor, for heating the zirconium element.

[0008] As a preferred mode, the height of the sealing material accounts for five-sixths of the height of the cylindrical hollow portion; and the height of the ceramic piece accounts for one-sixth of the height of the cylindrical hollow portion.

[0009] As a preferred mode, the shaft shoulder is hexagonal.

[0010] As a preferred mode, the maximum gap between the surface of the rectangular through hole and the surface of the zirconium element is 0.1 mm.

[0011] As a preferred mode, the sealing material is sintered to the lower part of the cylindrical hollow portion.

[0012] As a preferred mode, the shell bottom further has a shell bottom plane and the lower shield connection flange, the lower shield connection flange extends vertically along the edge of the shell bottom plane; and the lower shield has an outer cylinder and an inner cylinder, the outer cylinder has a flange, the lower shield connection flange is riveted on the flange of the outer cylinder, and when the lower shield connection flange rivets the flange, the top end of the inner cylinder abuts against the shell bottom plane.

[0013] In another aspect, the utility model provides a kind of oxygen sensor, it includes the probe subassembly of preceding.

[0014] The oxygen sensor for detecting oxygen content of automobile exhaust system of the utility model, by detecting oxygen concentration, feedback to vehicle ECU carries out closed-loop control correction fuel injection amount, to reach the best emission.Heated and non-heated of prior art oxygen sensor, switch type or wide range type universally use talcum powder and ceramic insulator are sealed by one or more times of press fitting.The accuracy of sensor signal is determined by the quality of sealing, the current problem is that internal leakage is difficult to control, in addition, complex structure, higher cost.The focus of the utility model is to change from design, namely reduce cost, simultaneously solve sealing problem.

[0015] Compared with prior art, the oxygen sensor of the utility model can effectively control the internal leakage of oxygen sensor, and has high sealing performance, is not easy to fall off powder, to avoid causing pollution, and its structure is simple, low in cost, extremely beneficial to product production and market promotion.

[0016] The utility model has the following advantages:

[0017] 1, the structure of product is greatly simplified compared with prior art, and material cost is reduced.

[0018] 2, new sealing material and new solidification structure greatly improve the stability of sealing control, effectively improve the service life of product. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the three-dimensional structure schematic diagram of the probe subassembly embodiment of the oxygen sensor of the utility model, and lower shield and zirconium element are not shown.

[0020] Figure 2 It is the shell section view schematic diagram of the probe subassembly embodiment of the utility model.

[0021] Figure 3 It is the section view schematic diagram of the probe subassembly embodiment of the oxygen sensor of the utility model.

[0022] Figure 4 It is the section view schematic diagram of the oxygen sensor embodiment of the utility model. DETAILED DESCRIPTION

[0023] In the following, the embodiment of the oxygen sensor of the utility model will be described with reference to the drawings.

[0024] The embodiments described herein are specific embodiments of the present application, are used to illustrate the concept of the present application, and are explanatory and exemplary, and should not be interpreted as limiting the embodiments of the present application and the scope of the present application. In addition to the embodiments described herein, those skilled in the art can also employ other technical solutions that are obvious based on the content disclosed in the claims and the description of the present application, which include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0025] The drawings of the present specification are schematic drawings that assist in illustrating the concept of the present application and schematically represent the shape of each part and the relationship between them.

[0026] Figure 1 The exploded view of the probe sub-assembly of the oxygen sensor of the present application is shown, without the lower shield and the zirconium element. Figure 2 The exploded view of the probe sub-assembly of the present application is shown. Figure 3 The exploded view of the probe sub-assembly of the oxygen sensor of the present application is shown. Figure 4 The exploded view of the oxygen sensor of the present application is shown.

[0027] As Figure 4 shown, the oxygen sensor of the present application includes a probe sub-assembly and a wiring harness structure.

[0028] As Figure 1 , 2 and 3, the probe sub-assembly of the oxygen sensor of the present application includes a housing 1, a sealing material 2, a ceramic piece 3, a zirconium element 4, and a lower shield 5. The probe sub-assembly has a central axis as shown in Figure 2 .

[0029] The zirconium element 4 is an elongated strip with a rectangular cross-section, arranged to pass through the housing 1 along the central axis of the housing 1, as well as the ceramic piece 3 and the sealing material 2 located in the housing 1. The surface of the zirconium element 4 is printed with a heating circuit, which includes a heating resistor, for heating the zirconium element 4.

[0030] The housing 1 is a U-shaped cylindrical housing, including an upper opening 16, a housing bottom, and a cylindrical hollow portion extending from the upper opening 16 to the housing bottom, the outer surface of the housing 1 includes, in order along the central axis, an upper opening edge, an upper fastening cylinder, a shoulder 11, a lower connecting threaded cylinder, and a lower shield connecting flange 141, please note that these parts of the outer surface of the housing 1 are connected in order, without spacing.

[0031] The housing bottom has a housing bottom plane 14, a lower shield connecting flange 141, and a through hole 17. The lower shield connecting flange 141 extends vertically along the edge of the housing bottom.

[0032] The through hole 17 is located on the central axis of the housing 1, and the cross section of the through hole 17 is rectangular, for the zirconium element 4 to pass through, and the maximum gap between the four surfaces of the rectangular through hole 17 and the corresponding four surfaces of the zirconium element 4 is 0.1 mm.

[0033] Referring again to Figure 3 , the lower shield 5 has an outer cylinder 51 and an inner cylinder 52, and the outer cylinder 51 has a flange. The lower shield connecting flange 141 is used to connect the lower shield 5, and the lower shield 5 and the housing 1 are connected by riveting the lower shield connecting flange 141 on the flange of the outer cylinder 51. When the lower shield connecting flange 141 is riveted on the flange of the outer cylinder 51, the top end of the inner cylinder 52 abuts against the bottom plane 14 of the housing. It is preferable to rivet the lower shield connecting flange 141 on the flange of the outer cylinder 51 all around, so that first, it ensures that the gas enters from the opening of the lower shield, rather than leaking from the gap; second, it makes the fixation more secure.

[0034] Referring again to Figure 4 , the upper fastening cylinder is used to connect the upper shield of the oxygen sensor by tight fit.

[0035] The outer surface of the lower connecting threaded cylinder has threads for connecting the interface threads of the exhaust pipe of the vehicle. In this embodiment, the threads on the outer surface of the lower connecting threaded cylinder extend along the entire length of the lower connecting threaded cylinder, and have a tool withdrawal groove.

[0036] The sealing material 2 fills the lower part of the cylindrical hollow part, and tightly contacts the zirconium element 4 and the surface of the cylindrical hollow part.

[0037] The ceramic piece 3 is located in the upper part of the cylindrical hollow part, and is press-fitted on the sealing material 2, and the ceramic piece 3 is fixed by riveting the upper opening edge. It is preferable to rivet the upper opening edge on the ceramic piece 3 all around, so that the fixation of the part is tight, and the part is not easy to loosen if riveting is distributed.

[0038] In addition to leaving the upper opening edge for press-fitting the ceramic piece 3, the ceramic piece 3 and the sealing material 2 fill the cylindrical hollow part. The sealing material 2 occupies most of the space of the cylindrical hollow part, and the ceramic piece 3 only occupies a small part of the space of the cylindrical hollow part. The height of the sealing material 2 accounts for, for example, five-sixths or four-fifths of the height of the cylindrical hollow part, and the height of the ceramic piece 3 accounts for, for example, one-sixth or one-fifth of the height of the cylindrical hollow part.

[0039] In this embodiment, the shoulder 11 is hexagonal. The shoulder 11 is used to install and rotate the probe sub-assembly, and can also be quadrangular or pentagonal, or circular, or the surface can be knurled.

[0040] The sealing material 2 is formed in the lower part of the cylindrical hollow part by sintering.

[0041] The proportioning of the sealing material 2 is as follows:

[0042] 1. 30% to 50% talc powder, the main component of talc powder is magnesium silicate, as the main material of sealing material 2;

[0043] 2. 30% to 50% glass powder, the softening temperature of the glass powder is 600-700℃, which fuses the talc powder together and improves the air tightness.

[0044] 3. 10% to 15% magnesium stearate, which is used as a lubricant to facilitate the flow and granulation of the powder during the preparation of the powder.

[0045] The preparation process of the sealing material 2 is as follows:

[0046] According to the determined proportion, talc powder, glass powder and magnesium stearate are weighed and taken, and the powder mixture is put into a stirrer and stirred uniformly with a proper amount of pure water. Then, the above-mentioned mixture is put into an oven for drying. After drying, the sealing material 2 contains 5% moisture, and is granulated with an 80-mesh or 100-mesh screen.

[0047] The probe subassembly of the present application is assembled by the following steps:

[0048] First, take the zirconium element 4;

[0049] Secondly, put the zirconium element 4 into the shell 1;

[0050] Then, inject a proper amount of granulated sealing material 2;

[0051] Thirdly, press the ceramic piece 3: press the ceramic piece 3 to the fixed position and rivet the packaging, that is, rivet the edge of the opening 16 of the central cylindrical cavity of the shell 1 to fix the ceramic piece 3;

[0052] Finally, sintering and curing: put the pressed oxygen sensor probe subassembly into a high-temperature furnace, heat to 650-700℃, keep warm for 20-60min, and cool down with the furnace. Please note that the sintering holding time can be preferably 20min, 30min, 40min, but not less than 20min, because generally batch production is produced, and there is a heat radiation process during sintering, and the minimum time guarantees heat penetration of a batch of sintered parts.

[0053] The oxygen sensor of the present application is compared with the oxygen sensor of the prior art in terms of leakage, and the steps are as follows:

[0054] 1. Take the oxygen sensor probe subassembly made of existing talc block, as a comparison piece, measure the leakage value and record it;

[0055] 2, take the prepared sealing material 2, install the zirconium element 4 into the shell 1, fill the sealing material 2 and compact, install the ceramic piece 3 into the shell 1, press and rivet, measure the leakage value and record;

[0056] 3, the prior art oxygen sensor is assembled, the leakage value is measured and recorded;

[0057] 4, the assembled comparative piece and test piece are placed in a high temperature furnace, 650 DEG C is kept for 30 min (high temperature and keeping, simulate high temperature of real vehicle test), after furnace is reduced to normal temperature, the leakage value of the comparative piece and test piece is tested and recorded.

[0058] The results of the comparative test are as follows:

[0059]

[0060] From the test results, it can be seen that the leakage value of the talc block of the prior art oxygen sensor increases by 0.07-0.08 cc after high temperature sintering, which increases by about 40%. And the sealing structure and sealing material 2 of the oxygen sensor of the utility model, the leakage value decreases by 0.05-0.06 cc after high temperature sintering, which is reduced by about 25% compared with the prior art; therefore, the oxygen sensor of the utility model has a positive effect on improving the leakage rate.

[0061] At the same time, the improved sealing structure of the oxygen sensor of the utility model effectively reduces the number of parts and greatly reduces the production cost.

[0062] The oxygen sensor of the utility model can effectively control the internal leakage of the oxygen sensor, has high sealing performance, is not easy to fall off powder, and avoids causing pollution; and the oxygen sensor of the utility model has simple structure, low cost, and is extremely beneficial to product production and market promotion.

[0063] The utility model has the following advantages compared with the prior art:

[0064] 1, the structure of the product is greatly simplified compared with the prior art, and the material cost is reduced.

[0065] 2, the new sealing material 2 and the new solidification structure greatly improve the stability of sealing control and effectively improve the service life of the product.

[0066] The embodiments of the oxygen sensor of the present application are described above, and the purpose is to explain the spirit of the present application. Please note that the skilled in the art can modify and combine the features of the above-mentioned embodiments without departing from the spirit of the present application, therefore, the present application is not limited to the above-mentioned embodiments. The specific features of the oxygen sensor such as shape, size and position can be designed according to the role of the above-mentioned features, and these designs are all achievable by the skilled in the art. Moreover, the above-mentioned technical features are not limited to the disclosed combinations with other features, and the skilled in the art can also make other combinations between technical features according to the purpose of the present application, and the purpose of the present application is the criterion.

Claims

1. A probe sub-assembly for an oxygen sensor, characterized by, The probe subassembly comprises a zirconium element, a shell, a ceramic piece, a sealing material and a lower shield, wherein, the zirconium element is a long strip with a rectangular cross section, arranged to pass through the shell along the central axis of the shell and the ceramic piece and the sealing material located in the shell; the shell is a U-shaped cylindrical shell, comprising an upper opening, a shell bottom and a cylindrical hollow part extending from the upper opening to the shell bottom, the outer surface of the shell comprises, along the central axis, an upper opening edge, an upper fastening cylinder, a shoulder, a lower connecting threaded cylinder and a lower shield connecting flange connected in sequence, wherein, the shell bottom has a rectangular cross section through hole located on the central axis of the shell for the zirconium element to pass through; the upper fastening cylinder is used to connect the upper shield of the oxygen sensor by tight fit; the lower shield connecting flange is used to connect the lower shield; the outer surface of the lower connecting threaded cylinder has threads for connecting the interface threads of the vehicle exhaust pipe; the sealing material fills the lower part of the cylindrical hollow part and tightly contacts the surface of the zirconium element and the cylindrical hollow part; the ceramic piece is located in the upper part of the cylindrical hollow part, is press-fitted on the sealing material and is fixed by riveting the upper opening edge.

2. The probe subassembly according to claim 1, wherein, the surface of the zirconium element is printed with a heating circuit comprising a heating resistor for heating the zirconium element.

3. The probe subassembly according to claim 1, wherein, the height of the sealing material accounts for five-sixths of the height of the cylindrical hollow part; the height of the ceramic piece accounts for one-sixth of the height of the cylindrical hollow part.

4. The probe sub-assembly of claim 1, wherein, the shoulder is hexagonal.

5. The probe subassembly according to claim 1, wherein, the maximum gap between the surface of the rectangular through hole and the surface of the zirconium element is 0.1 mm.

6. The probe subassembly according to claim 1, wherein, the sealing material is sintered in the lower part of the cylindrical hollow part.

7. The probe subassembly according to claim 1, wherein, the shell bottom further has a shell bottom plane and the lower shield connecting flange vertically extends along the edge of the shell bottom plane; and the lower shield has an outer cylinder and an inner cylinder, the outer cylinder has a flange, the lower shield connecting flange is riveted on the flange of the outer cylinder, and when the lower shield connecting flange is riveted on the flange, the top end of the inner cylinder abuts against the shell bottom plane.

8. An oxygen sensor characterized by comprising: The probe subassembly comprises any one of the probe subassemblies according to claims 1-7.

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