Thin film vacuum pressure sensor

Abstract

The upper concave annular surface on the bottom surface of the upper seat body is arc-shaped and concaves upward, the film will not contact the upper concave annular surface when being deformed, the structure change caused by the contact between the film and the upper seat body when being deformed is avoided, no indentation is formed on the film, the film is smooth and is deformed, the air pressure change in the inner cavity of the upper seat body is more stable, the capacitance value changes stably with the film, and the measurement accuracy is improved. Double-layer baffles are arranged on the upper seat body, the double-layer baffles respectively shunt the air pressure and absorb pressure impact, the instantaneous impact deformation of the film is avoided, the overflow holes on the two layers of baffles are misaligned, the airflow flow path is prolonged, the film is effectively buffered and deformed at a slow and stable speed, and the measurement accuracy is further improved.

Description

Technical Field

[0001] This utility model relates to a thin-film vacuum pressure sensor, belonging to the field of vacuum measurement technology. Background Technology

[0002] A thin-film vacuum pressure sensor, also known as a thin-film vacuum gauge, is used to detect the vacuum level of a vacuum chamber. It includes an upper body, a lower body, a thin film, a sensing electrode, and a baffle. The thin film is welded between the upper and lower bodies, sealing and separating their inner cavities. The sensing electrode, housed in the lower body, forms a capacitor with the thin film. An overflow hole is provided on the baffle, which is installed in the upper body to divert airflow when the pressure changes. Air tubes are fixed to both the lower and upper bodies. In the non-operating state, the lower body is evacuated and its air tubes are sealed, creating a vacuum chamber within the lower body. The thin film remains within the lower body's inner cavity. As the pressure decreases, the membrane moves closer to the sensing electrode. During operation, the air tube of the upper body is sealed to the chamber, and a vacuum is drawn into the chamber. When the vacuum level in the chamber is greater than that in the lower body's inner cavity, the diaphragm bulges upwards, causing the capacitor to obtain different capacitance values, which become the measurement signal. The measurement signal is transmitted via the connection of the sensing electrode to the host computer or display, directly showing the corresponding vacuum level, thus measuring the vacuum level of the vacuum chamber. Therefore, the upward bulging deformation of the diaphragm determines the accuracy of the measurement. However, the following two defects affect the accuracy of the measurement: 1. The bottom surface of the upper body opposite the diaphragm is a plane. Multiple stepped surfaces are milled on the upper body to increase the distance between the diaphragm and the plane. However, when the diaphragm bulges and deforms, it will come into contact with the corner of the step, leaving indentations on the diaphragm. This causes changes in the diaphragm structure, resulting in unstable air pressure changes in the inner cavity of the upper body and unstable capacitance values, which affects the accuracy of the measurement.

[0003] 2. When the air pressure changes, the baffle's diversion effect is limited, the membrane is subjected to a large impact, the bulging and deformation speed is fast, the capacitance value changes too quickly, which will also affect the detection accuracy. Utility Model Content

[0004] The thin-film vacuum pressure sensor provided by this utility model avoids structural changes caused by the thin film contacting the edges of the upper body when it bulges and deforms. The air pressure change in the inner cavity of the upper body is more stable during the deformation of the thin film, so that the capacitance value changes smoothly with the bulging of the thin film. It also extends the airflow path, effectively buffers the bulging of the thin film, and makes the thin film deform slowly and smoothly, thus improving the measurement accuracy.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A thin-film vacuum pressure sensor includes an upper body, a lower body, a thin film welded between the upper and lower bodies and sealingly separating the inner cavities of the upper and lower bodies, and a baffle welded in the upper body and having a flow hole, the baffle being located above the thin film. The upper body has an arc-shaped, upwardly concave annular surface on its bottom surface, located between the baffle and the thin film. When the thin film bulges, it is separated from and does not contact the upwardly concave annular surface.

[0006] Preferably, the bottom surface of the upper seat has an outer ring plane located outside the concave annular surface. The outer edge of the film is welded along the outer ring plane. The concave annular surface is located above the welded annular plane and is transitioned to the outer annular plane by a stepped surface. The stepped surface is separated from the film and does not contact it.

[0007] Preferably, the upper seat is provided with two layers of baffles.

[0008] Preferably, the two baffles are a lower baffle and an upper baffle with an outer diameter smaller than that of the lower baffle, and the flow holes on the upper baffle are not aligned with those on the lower baffle.

[0009] Preferably, the upper baffle is flush with the bottom of the air hole on the upper seat.

[0010] The beneficial effects of this utility model are: The thin-film vacuum pressure sensor of this invention features an arc-shaped, upwardly recessed annular surface on the bottom surface of the upper body. When the thin film bulges and deforms, it will not contact the concave annular surface, thus avoiding structural changes caused by contact between the thin film and the edges of the upper body during bulging and deformation. No indentation will be formed on the thin film, and the thin film will bulge smoothly. During the deformation of the thin film, the air pressure change in the inner cavity of the upper body is more stable, so that the capacitance value changes smoothly with the bulging of the thin film, improving measurement accuracy.

[0011] Double-layer baffles are installed on the upper body. The double-layer baffles divert the air pressure and absorb the pressure impact to avoid instantaneous impact deformation of the membrane. The flow holes on the two layers of baffles are not aligned, which prolongs the airflow path and forms an effective buffer against the bulging of the membrane, so that the membrane deforms slowly and smoothly, further improving the measurement accuracy. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a thin-film vacuum pressure sensor in a specific embodiment.

[0013] Figure 2 This is a half-sectional schematic diagram of the thin film welded to the bottom of the upper body. Detailed Implementation

[0014] The following is combined Figures 1-2 The embodiments of this utility model will be described in detail below.

[0015] A thin-film vacuum pressure sensor includes an upper body 1, a lower body 2, a thin film 3 welded between the upper body 1 and the lower body 2 and sealingly separating the inner cavities of the upper and lower bodies, and a baffle 4 welded in the upper body 1 and having a flow hole. The baffle 4 is located above the thin film 3. The upper body 1 has an arc-shaped and upwardly concave annular surface 5 on its bottom surface. The annular surface 5 is located between the baffle 4 and the thin film 3. When the thin film 3 is bulging, it is separated from the annular surface 5 and does not contact it.

[0016] The thin-film vacuum pressure sensor described above has an arc-shaped and upwardly recessed annular surface 5 on the bottom surface of the upper body 1. When the thin film 3 bulges and deforms, it will not contact the concave annular surface 5, thus avoiding structural changes caused by contact between the thin film and the edges of the upper body during bulging and deformation. No indentation will be formed on the thin film, and the thin film 3 bulges with a smooth surface. During the deformation of the thin film 3, the air pressure change in the inner cavity of the upper body is more stable, so that the capacitance value changes smoothly with the bulging of the thin film 3, thereby improving the measurement accuracy.

[0017] The upper seat has an outer ring plane 6 on its bottom surface, located outside the concave annular surface 5. The outer edge of the film 3 is welded along the outer ring plane 6. The concave annular surface 5 is located above the welded annular plane 6 and is transitioned to the outer annular plane 6 by a stepped surface 7. The stepped surface 7 is separated from the film 3 and does not contact it. Figure 2 As shown, the outer annular plane 6 is the welding surface with the film 5. The concave annular surface 5 is located in the inner ring of the outer annular plane 6 and is located on the upper side of the outer annular plane 6. The step surface 7 is the transition between the outer annular plane 6 and the concave annular surface 5. When the film 3 bulges upward, the bulging height gradually decreases from the inside to the outside. The step surface 7 is close to the outer annular plane 6. The height of the film 3 bulging upward relative to the step surface 7 is small. After the film 3 bulges, it will not form contact with the step surface 7. The step surface 7 will not interfere with the bulging of the film 3.

[0018] The upper body 1 is provided with two layers of baffles 4. The double-layer baffles 4 on the upper body 1 divert the air pressure and absorb the pressure impact, avoiding instantaneous impact deformation of the diaphragm 3, making the bulging deformation of the diaphragm smoother, reducing the impact of the diaphragm 3, and improving the measurement accuracy.

[0019] The two baffles 4 consist of a lower baffle 41 and an upper baffle 42 with an outer diameter smaller than that of the lower baffle 41. The flow holes on the upper baffle 42 are not aligned with those on the lower baffle 41. This misalignment of the flow holes on the two baffles extends the airflow path, effectively buffering the bulging of the membrane and allowing the membrane 3 to deform slowly and smoothly, further improving measurement accuracy.

[0020] The upper baffle 42 is flush with the bottom of the air hole 11 on the upper body 1. This facilitates the welding and positioning of the upper baffle 42 on the upper body 1, simplifies the structure of the inner cavity of the upper body 1, and improves the assembly convenience of the sensor.

[0021] The technical solutions of the embodiments of this utility model have been fully described above with reference to the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

Claims

1. A thin-film vacuum pressure sensor, comprising an upper body, a lower body, a thin film welded between the upper and lower bodies and sealingly separating the inner cavities of the upper and lower bodies, and a baffle welded into the upper body and having a flow-through hole, the baffle being located above the thin film, characterized in that: The upper seat has an arc-shaped, upwardly concave annular surface on its bottom surface. The concave annular surface is located between the baffle and the diaphragm. When the diaphragm bulges, it is separated from the concave annular surface and does not contact it.

2. The thin-film vacuum pressure sensor according to claim 1, characterized in that: The upper seat has an outer ring plane on its bottom surface located outside the concave annular surface. The outer edge of the film is welded along the outer ring plane. The concave annular surface is located above the welded annular plane and is transitioned to the outer annular plane by a stepped surface. The stepped surface is separated from the film and does not contact it.

3. The thin-film vacuum pressure sensor according to claim 1, characterized in that: The upper body is provided with two layers of baffles.

4. The thin-film vacuum pressure sensor according to claim 3, characterized in that: The two baffles are a lower baffle and an upper baffle with an outer diameter smaller than the lower baffle. The flow holes on the upper baffle are not aligned with the flow holes on the lower baffle.

5. The thin-film vacuum pressure sensor according to claim 4, characterized in that: The upper baffle is flush with the bottom of the air hole on the upper body.

Images