A new type of capacitive signal position sensor

Abstract

The present invention relates to the technical field of electric irons, and in particular to a novel capacitance signal position sensor, comprising an upper cover and a lower cover that cooperates with the upper cover to form a sealed cavity, at least three mutually insulated metal guide pins are fixedly arranged on the lower cover, a metal ball and a liquid medium that can roll freely as the cavity tilts are arranged in the cavity, the metal ball is in unreliable contact with one of the metal guide pins when rolling in the cavity, and the liquid medium is used to increase the capacitance when the metal ball and the metal guide pin are in unreliable contact. Compared with the air medium sensor, the novel capacitance signal position sensor provided by the present invention increases the capacitance between the metal ball and the metal guide pin that is in unreliable contact with it, increases the change ratio of the capacitance, and thus improves the signal strength and reliability of the sensor; at the same time, the structure is simple, the production cost is saved compared with the sensor in the prior art, and the assembly of the sensor is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of electric irons, and in particular to a novel capacitance signal position sensor. Background Art

[0002] A capacitive sensor is a device that converts the change of the measured value into a change of capacitance. It is a variable capacitor. Because this sensor has the characteristics of simple structure, small size, good dynamic response, high sensitivity, high resolution, and non-contact measurement, it is widely used in displacement, acceleration, vibration, pressure, pressure difference, liquid level, equal content and other detection fields. The current capacitive sensor is usually composed of a shell, a sensing plate installed in the shell, a fixed structure and a detection chip. Among them, the sensing plate is usually manufactured separately, which has high requirements on the precision of the production equipment, otherwise it is easy to cause the size of the sensing plate to be different, thereby affecting the measurement accuracy; in addition, when assembling the sensing plate, fixed structure, detection chip and other components, the installation accuracy is also very high, which puts high demands on the production equipment and the assembly is time-consuming.

[0003] Therefore, in order to solve the shortcomings of the above-mentioned existing capacitive sensors, such as complex preparation, low precision and great difficulty in miniaturization, our company applied for an invention patent with application number 201210422577.2, proposing a sensing device of a capacitive sensor, including an upper cover, a printed circuit board matched with the upper cover, and three metal balls located in the cavity formed by the upper cover and the printed circuit board. The printed circuit board is fixed on the upper cover to form a complete sensing device of the capacitive sensor.

[0004] However, in the above patent, the sensor needs to be completed through multiple assembly processes including a printed circuit board, an upper cover, a lower cover, guide pins and a number of metal balls. In addition, due to the aforementioned limitations, the capacitance change caused by the metal balls is relatively small and is easily affected by the external environment during actual use. Summary of the invention

[0005] In order to solve the shortcomings of the capacitive sensors in the above-mentioned prior art, such as the complex assembly process and small capacitance change, the present invention provides a new type of capacitive signal position sensor, which can increase the capacitance change ratio of the sensor, thereby improving the signal strength, and simplify the component structure and process, thereby reducing production costs.

[0006] A novel capacitive signal position sensor provided by the present invention comprises an upper cover and a lower cover which cooperates with the upper cover to form a sealed cavity, wherein at least three mutually insulated metal guide pins are fixedly provided on the lower cover, and a metal ball and a liquid medium which can roll freely as the cavity tilts are provided in the cavity, wherein the metal ball is in unreliable contact with one of the metal guide pins when rolling in the cavity, and the liquid medium is used to increase the capacitance when the metal ball and the metal guide pin are in unreliable contact.

[0007] Furthermore, the metal guide needle includes a first metal guide needle, a second metal guide needle and a third metal guide needle, and the first metal guide needle is fixedly connected to the lower cover and is electrically conductive.

[0008] Furthermore, the second metal guide needle and the third metal guide needle are insulated and connected to the lower cover and extend out from both sides of the lower cover.

[0009] Furthermore, the first metal guide needle, the second metal guide needle and the third metal guide needle are respectively connected to a measuring circuit for reading the capacitance between the metal ball and the metal guide needle with which it is in non-reliable contact.

[0010] Furthermore, the upper cover is fixedly connected to the lower cover by welding, and the width of one end of the inner cavity of the upper cover is greater than the width of the other end, so that the position of the metal ball when the sensor is placed on its side is the same as the position when the sensor is placed flat.

[0011] Furthermore, the height of the inner cavity of the upper cover is greater than the diameter of the metal ball, and the narrowest part of the inner cavity of the upper cover is greater than the diameter of the metal ball.

[0012] Furthermore, the liquid medium is a mixed solution of water, propylene glycol and ethylene glycol.

[0013] Furthermore, the upper cover and the lower cover are made of steel, copper, aluminum or iron.

[0014] Furthermore, the metal guide needle is made of steel, copper, aluminum or iron.

[0015] Furthermore, the metal ball is made of steel, copper, aluminum or iron.

[0016] Compared with the prior art, the present invention provides a novel capacitive signal position sensor, which forms a sealed cavity by setting an upper cover and a lower cover to seal, a plurality of mutually insulated metal guide pins are set on the lower cover, and a rollable metal ball and a liquid medium are set in the sealed cavity; the present invention provides a novel capacitive signal position sensor, which increases the capacitance between the metal ball and the metal guide pin with which it is not in reliable contact, and increases the change ratio of the capacitance, thereby improving the signal strength and reliability of the sensor; at the same time, the structure is simple, the production cost is saved compared with the sensor in the prior art, and the assembly of the sensor is simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic diagram of the structure of the sensor provided by the present invention;

[0019] Figure 2 An exploded diagram of the sensor provided by the present invention;

[0020] Figure 3 A schematic diagram of the upper cover provided by the present invention;

[0021] Figure 4 A comparison table of air medium and liquid medium of the sensor provided by the present invention.

[0022] Reference numerals:

[0023] 10 upper cover 11 lower cover 20 metal guide pin

[0024] 21 first metal guide needle 22 second metal guide needle 23 third metal guide needle

[0025] 30 metal balls DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0028] like Figure 1 , Figure 2 As shown, a novel capacitive signal sensor provided by the present invention comprises an upper cover 10, and a lower cover 11 which cooperates with the upper cover 10 to form a sealed cavity, at least three mutually insulated metal guide pins 20 are fixedly provided on the lower cover 11, a metal ball 30 which can roll freely as the cavity tilts and a liquid medium are provided in the cavity, the metal ball 30 is in unreliable contact with one of the metal guide pins 20 when rolling in the cavity, and the liquid medium is used to increase the capacitance when the metal ball 30 and the metal guide pin 20 are in unreliable contact.

[0029] When implementing it, Figure 1 As shown, the upper cover 10 and the lower cover 11 are sealed by welding and fusion to form a sealed cavity. The upper cover 10 and the lower cover 11 are both made of metal, and the material of the upper cover 10 and the lower cover 11 is steel, copper, aluminum or iron. Preferably, in this embodiment, the material of the upper cover 10 and the lower cover 11 is steel; at least three mutually insulated metal guide pins 20 are fixedly provided on the lower cover 11, and the material of the metal guide pins 20 is steel, copper, aluminum or iron. Preferably, in this embodiment, the material of the metal guide pins 20 is steel.

[0030] like Figure 1 , Figure 2 As shown, a metal ball 30 and a liquid medium are provided in the sealed cavity formed by the upper cover 10 and the lower cover 11. The metal ball 30 is made of steel, copper, aluminum or iron. Preferably, in the present embodiment, the metal ball 30 is made of steel. When the metal ball 30 rolls in the cavity, it is in non-reliable contact with one of the metal guide pins 20. The capacitance between the metal ball 30 and the metal guide pin 20 in non-reliable contact is greater than the capacitance between the metal ball 30 and the metal guide pin 20 in non-reliable contact.

[0031] like Figure 1 , Figure 2As shown, specifically, in this embodiment, the number of the metal guide pins 20 is three, and the metal guide pins 20 include a first metal guide pin 21, a second metal guide pin 22, and a third metal guide pin 23 that are insulated from each other. The side of the first metal guide pin 21 facing the upper cover 10 does not pass through the lower cover 11, that is, the first metal guide pin 21 does not extend out of the side of the lower cover 11, and the first metal guide pin 21 is not located in the sealed cavity; the first metal guide pin 21 is spot-welded to the lower cover 11, and the first metal guide pin 21 is electrically conductive to the lower cover 11. The metal ball 30 is located in the sealed cavity and contacts the lower cover 11, that is, it contacts and conducts with the first metal guide pin 21.

[0032] like Figure 1 , Figure 2 As shown, the second metal guide pin 22 and the third metal guide pin 23 are sintered and insulated and fixedly connected to the lower cover 11 through glass bead sintering. The second metal guide pin 22 and the third metal guide pin 23 are respectively located on both sides of the first metal guide pin 21. The second metal guide pin 22 and the third metal guide pin 23 extend relative to both sides of the lower cover 11. The second metal guide pin 22 and the third metal guide pin 23 pass through the lower cover 11 and are located in the sealed cavity on one side facing the upper cover 10. Glass bead sintering is a common sintering in the prior art and will not be described in detail herein.

[0033] Preferably, the first metal guide needle 21, the second metal guide needle 22 and the third metal guide needle 23 are electrically connected to a measuring circuit respectively, and the measuring circuit is used to read the capacitance between the metal ball 30 and the first metal guide needle 21 and the second metal guide needle 22 or the third metal guide needle 23. The measuring circuit is a common measuring circuit in the prior art and will not be described in detail here.

[0034] like Figure 3 As shown, preferably, the width of one end of the inner cavity of the upper cover 10 is greater than the width of the other end, the narrowest part of the inner cavity width of the upper cover 10 is greater than the diameter of the metal ball 30, and the height of the inner cavity of the upper cover 10 is greater than the diameter of the metal ball 30; the metal ball 30 can roll in the sealed cavity formed by the upper cover 10 and the lower cover 11, while ensuring that when the sensor is placed on its side, the position of the metal ball 30 is the same as when the sensor is placed flat.

[0035] According to the capacitance C≈ε*S / d, d is the gap between the metal ball 30 and the metal guide pin 20, or the gap between the metal ball 30 and the metal guide pin 20 caused by the oxide layer of the metal ball 30, so the metal ball 30 and the metal guide pin 20 are in unreliable contact; S is the surface area of ​​the contact surface between the metal ball 30 and the metal guide pin 20, and ε is the dielectric constant determined by the material of the space in the cavity. The capacitance between the first metal guide pin 21 and the second metal guide pin 22 is set to C12, and the capacitance between the first metal guide pin 21 and the third metal guide pin 23 is set to C23.

[0036] like Figure 4As shown, when the cavity is filled with air, the value of ε is 1, and the difference in capacitance between the metal ball 30 and the metal guide pin 20 with which it is not in reliable contact and the metal ball 30 and the metal guide pin 20 with which it is not in reliable contact is 0.1PF; since the basic capacity and capacity difference of the air medium sensor are small, the air medium sensor is easily affected by the external environment, and therefore needs to be protected by means such as pin sealing, which increases the production cost.

[0037] like Figure 4 As shown, when the cavity is filled with liquid, the value of ε is 80, and the difference in capacitance between the metal ball 30 and the metal guide needle 20 with which it is in non-reliable contact and the metal guide needle 20 with which the metal ball 30 is not in non-reliable contact is 90PF; the liquid medium not only increases the basic capacitance, but also increases the capacitance between the metal ball 30 and the metal guide needle 20 with which it is in non-reliable contact, increases the capacitance change ratio, and thereby improves the signal strength of the sensor and the reliability of the sensor.

[0038] Specifically, the liquid medium is a mixed solution of water, propylene glycol and ethylene glycol, and the volume ratio of water, propylene glycol and ethylene glycol is 2:1:2. The mixed solution of water, propylene glycol and ethylene glycol is used as the liquid medium to reduce the viscosity of ethylene glycol, so that the metal ball 30 can roll flexibly in the sealed cavity. Under the action of the gravity of the metal ball 30, the metal ball 30 is ensured to contact the lower cover 11 or the upper cover 10; at the same time, the freezing point of the liquid is lowered, so that the liquid medium cannot freeze in an environment of -10 degrees Celsius, and in an environment of 100 degrees Celsius or above 100 degrees Celsius, the liquid medium cannot boil and thus cannot affect the measurement reading of the capacitance and the performance of the capacitance sensor.

[0039] The present invention provides a novel capacitance signal position sensor, which is used in actual production and assembly. Figure 1 , Figure 2 As shown, first, the upper cover 10 is turned upside down so that the inner cavity of the upper cover 10 faces upward, then the metal ball 30 is placed into the upper cover 10, and the liquid medium is added. Then, the lower cover 11 with the metal guide pin 20 is covered, and the upper cover 10 and the lower cover 11 are welded and fused along the seam between the two.

[0040] In actual measurement, Figure 1 , Figure 2 As shown, the first metal guide needle 21, the second metal guide needle 22 and the third metal guide needle 23 are all electrically connected to the measuring circuit, and the measuring circuit measures and reads the capacitance values ​​between the metal ball 30 and the second metal guide needle 22 and the third metal guide needle 23 respectively. The liquid medium not only increases the basic capacitance, but also increases the capacitance between the metal ball 30 and the metal guide needle 20 with which it is not in reliable contact.

[0041] When the actual operating sensor position changes, such as Figure 1 , Figure 2 , Figure 4 As shown, the metal ball 30 moves in the sealed cavity and makes unreliable contact with the second metal guide needle 22 or the third metal guide needle 23. When the metal ball 30 makes unreliable contact with the second metal guide needle 22, the capacitance value C12 is significantly greater than C23. When the metal ball 30 makes unreliable contact with the third metal guide needle 23, the capacitance value C23 is significantly greater than C12.

[0042] Compared with the prior art, the present invention provides a novel capacitive signal position sensor, which forms a sealed cavity by setting an upper cover and a lower cover to seal, a plurality of mutually insulated metal guide pins are set on the lower cover, and a rollable metal ball and a liquid medium are set in the sealed cavity; the present invention provides a novel capacitive signal position sensor, which increases the capacitance between the metal ball and the metal guide pin with which it is not in reliable contact, and increases the change ratio of the capacitance, thereby improving the signal strength and reliability of the sensor; at the same time, the structure is simple, the production cost is saved compared with the sensor in the prior art, and the assembly of the sensor is simplified.

[0043] Although the terms such as upper cover, lower cover, metal guide pin and metal ball are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel capacitive signal position sensor, characterized in that: The invention comprises an upper cover (10) and a lower cover (11) which cooperates with the upper cover (10) to form a sealed cavity, wherein at least three mutually insulated metal guide pins (20) are fixedly provided on the lower cover (11), and a metal ball (30) and a liquid medium which can roll freely as the cavity tilts are provided in the cavity, wherein the metal ball (30) is in non-reliable contact with one of the metal guide pins (20) when rolling in the cavity, and the liquid medium is used to increase the capacitance of the metal ball (30) and the metal guide pin (20) when they are in non-reliable contact; Wherein, the liquid medium is a mixed solution of water, propylene glycol and ethylene glycol, and the volume ratio of water, propylene glycol and ethylene glycol is 2:1:

2.

2. A novel capacitive signal position sensor according to claim 1, characterized in that: The metal guide needle (20) comprises a first metal guide needle (21), a second metal guide needle (22) and a third metal guide needle (23); the first metal guide needle (21) is fixedly connected to the lower cover (11) and is electrically conductive.

3. A novel capacitive signal position sensor according to claim 2, characterized in that: The second metal guide needle (22) and the third metal guide needle (23) are insulated and connected to the lower cover (11) and extend out from both sides of the lower cover (11).

4. A novel capacitive signal position sensor according to claim 3, characterized in that: The first metal guide needle (21), the second metal guide needle (22), and the third metal guide needle (23) are respectively connected to a measuring circuit for reading the capacitance between the metal ball (30) and the metal guide needle (20) with which it is in non-reliable contact.

5. A novel capacitive signal position sensor according to claim 2, characterized in that: The upper cover (10) is fixedly connected to the lower cover (11) by welding, and the width of one end of the inner cavity of the upper cover (10) is greater than the width of the other end, so that the position of the metal ball (30) when the sensor is placed on its side is the same as the position when the sensor is placed flat.

6. A novel capacitive signal position sensor according to claim 5, characterized in that: The height of the inner cavity of the upper cover (10) is greater than the diameter of the metal ball (30), and the narrowest part of the inner cavity of the upper cover (10) is greater than the diameter of the metal ball (30).

7. A novel capacitive signal position sensor according to claim 1, characterized in that: The liquid medium is a mixed solution of water, glycerol and ethylene glycol.

8. The novel capacitive signal position sensor according to claim 1 is characterized in that: The upper cover (10) and the lower cover (11) are made of steel, copper, aluminum or iron.

9. The novel capacitive signal position sensor according to claim 1 is characterized in that: The material of the metal guide needle (20) is steel, copper, aluminum or iron.

10. The novel capacitive signal position sensor according to claim 1, characterized in that: The material of the metal ball (30) is steel, copper, aluminum or iron.

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