Aerostatic bearing with self-detection capability

Abstract

The invention discloses a gas static pressure bearing with self-detection capability. The gas static pressure bearing comprises a bearing body, a supporting body, a measuring circuit and a gas supply module, the bearing body is composed of a plurality of bearing blocks, each bearing block comprises a shell and a bearing face, and a supporting gas film is formed between the bearing face and the bearing body after gas is supplied. The bearing surface is divided into an inner layer structure and an outer layer structure which are bonded through an insulating material and connected with a measuring circuit. The inner and outer bearing surfaces and the bearing body form inner and outer capacitors respectively, and the outer capacitor is used for weakening the edge effect of the inner capacitor. And the two inner layer capacitors which are distributed oppositely and the bearing body form a capacitance displacement sensor with a differential structure. According to the bearing, non-contact suspension can be achieved through the bearing body structure, meanwhile, when the thickness of a bearing gas film changes, the change of the polar distance between the bearing face and the bearing body can be obtained by measuring the capacitance change of the inner layer capacitor, and in other words, the change of the thickness of the bearing gas film is automatically detected.

Description

Technical Field

[0001] The present invention relates to the fields of aerostatic bearing technology and sensor design, and particularly to an aerostatic bearing with self-detection ability. Background Art

[0002] Aerostatic bearing technology utilizes external high-pressure gas to expand and decompress through a throttle, and forms a stable high-pressure gas film in the bearing clearance to achieve load support. This technology directly uses the gas film pressure to generate suspension force, showing core advantages such as low friction loss in the start-stop stage, excellent load-bearing performance, high motion accuracy, and environmental friendliness and pollution-free. Its applications involve fields such as aerospace, ultra-precision machining, high-speed power equipment, and semiconductor manufacturing. When the bearing is in use, it is necessary to detect its operating state to ensure its performance, and the film thickness of the bearing gas film is an important operating state parameter. Common methods for measuring the film thickness of the gas film use external sensors. Since there are multiple operating state parameters of the bearing system that need to be measured, using an external sensor to measure the film thickness will further complicate the detection system of the bearing.

[0003] Capacitive sensors use various types of capacitors as sensing elements, converting the change in the measured physical quantity into the change in the capacitance of the capacitor, and can be divided into three types: variable pole pitch capacitive sensors, variable area capacitive sensors, and variable dielectric capacitive sensors. Among them, a capacitive displacement sensor is a sensor that converts the measured displacement change into the change in the capacitance of the capacitor, and it is generally a variable pole pitch capacitive sensor.

[0004] Figure 1 is a schematic diagram of a flat variable pole pitch capacitive displacement sensor. The capacitor consists of a fixed plate and a moving plate, and its initial capacitance is:

[0005]

[0006] In the formula, d0 is the initial plate spacing, A is the relative covering area of the plates, and ε is the dielectric constant of the medium between the plates. For a variable pole pitch capacitive displacement sensor, A and ε are constants.

[0007] When the plate distance of the capacitor decreases by Δd, the capacitance of the capacitor becomes:

[0008]

[0009] The change in capacitance is:

[0010]

[0011] The relative change in capacitance is:

[0012]

[0013] Expanding the above formula in the form of Taylor series and neglecting the high-order small terms in the expansion, the relationship between the change in capacitance and the change in plate spacing can be obtained as follows:

[0014]

[0015] When the change in pole pitch is very small, the change in capacitance ΔC and the change in pole pitch Δd show an approximately linear relationship. Summary of the Invention

[0016] In order to overcome the problem that the film thickness measurement of a gas static pressure bearing depends on an external sensor, resulting in a complex test system, the present invention proposes a gas static pressure bearing with self-detection ability.

[0017] The technical solution of the present invention is as follows:

[0018] A gas static pressure bearing with self-detection ability according to the present invention is characterized in that the gas static pressure bearing couples a film thickness measurement sensor with the bearing body, enabling the bearing to not only realize the suspension support function but also measure its own film thickness; the bearing body is composed of multiple bearing blocks, and a single bearing block includes a bearing housing, an inner bearing surface, an outer bearing surface, an inner insulator, and an outer insulator. The bearing body, the carrier, the measurement circuit, and the gas supply module form a gas static pressure bearing with self-detection ability; a gas supply channel is provided on the bearing housing; a throttling device is provided on the inner bearing surface; the gas supply module of the bearing structure inputs high-pressure gas into the bearing through the gas supply channel. When the high-pressure gas flows through the throttling device on the inner bearing surface, a throttling effect is generated, and finally, the gas flows out of the bearing. After the gas flows out of the bearing, a high-pressure gas film is formed between the bearing surface formed by the inner bearing surface, the inner insulator, and the outer bearing surface and the carrier, realizing the suspension support of the carrier.

[0019] Further, the form of the throttling device can be various throttling forms such as orifice throttling, slit throttling, and porous throttling, etc., for throttling the high-pressure gas.

[0020] Further, both the inner bearing surface and the outer bearing surface are made of conductive materials and are bonded together through the inner insulator. The outer bearing surface is then bonded to the bearing housing through the outer insulator.

[0021] Further, both the bearing housing and the carrier are grounded. The inner bearing surface and the outer bearing surface serve as two fixed electrodes and are both connected to an external measurement circuit through wires. The carrier serves as a moving electrode, and the gas in the gas film is used as a dielectric material to form two inner and outer capacitors. The outer capacitor is used to weaken the edge effect of the inner capacitor, making the electric field of the inner capacitor evenly distributed.

[0022] Further, the inner bearing surfaces of the two bearing blocks distributed oppositely respectively form upper and lower inner capacitors with the carrier, and the outer bearing surfaces of the two bearing blocks distributed oppositely respectively form upper and lower outer capacitors with the carrier.

[0023] Further, the four capacitors of the two bearing blocks distributed oppositely in total are connected to the same measurement circuit, and the two inner capacitors and the carrier form a differential-structured variable-gap capacitive displacement sensor.

[0024] Further, the bearing may also have only a single bearing block, which forms a capacitive sensor with the inner capacitor and the measurement circuit.

[0025] The beneficial effects of the present invention are as follows:

[0026] A gas static pressure bearing with self-detection ability of the present invention couples a capacitive displacement sensor with the gas static pressure bearing body, and the overall adopts a differential structure. The two bearing blocks distributed oppositely both have gas static pressure bearing structures, and the carrier between the bearing blocks is supported by the high-pressure gas film together to realize the suspension support of the carrier. At the same time, the two bearing blocks distributed oppositely and the carrier form a differential-structured capacitive displacement sensor. The position of the carrier in the two bearing blocks, that is, the gas film thickness of the bearing, can be measured through an external measurement circuit. Since the bearing is designed with a differential structure, the sensitivity of the bearing body as a capacitive displacement sensor for film thickness measurement is doubled, and the linearity is also improved. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of a variable-gap capacitive sensor. In the figure: 1. Fixed electrode plate; 2. Moving electrode plate.

[0028] Figure 2 It is a schematic diagram of the structure of a gas static pressure bearing with self-detection ability of the present invention. In the figure: 1. Bearing housing; 2. Outer insulator; 3. Outer bearing surface; 4. Inner insulator; 5. Inner bearing surface; 6. Air supply channel; 7. Throttle device; 8. Carrier; 9. Outer bearing surface of the bearing block opposite; 10. Inner bearing surface of the bearing block opposite.

[0029] Figure 3 It is a schematic diagram of the structure of a single-layer gas static pressure bearing with self-detection ability of the present invention. In the figure: 1. Bearing housing; 2. Outer insulator; 3. Outer bearing surface; 4. Inner insulator; 5. Inner bearing surface; 6. Air supply channel; 7. Throttle device; 8. Carrier. Detailed Embodiments

[0030] The present invention will be further described in detail below with reference to the drawings in the specification.

[0031] Embodiment 1

[0032] As Figure 2 shown, a gas static pressure bearing with self - detection ability provided by the present invention has a bearing body composed of four bearing blocks. A single bearing block includes a bearing housing 1, an inner load - bearing surface 5, an outer load - bearing surface 3, an inner insulator 4, and an outer insulator 2. The bearing body, a carrier 8, a measurement circuit, and a gas supply module form a gas static pressure bearing with self - detection ability.

[0033] Both the inner load - bearing surface 5 and the outer load - bearing surface 3 are made of conductive materials and are bonded together through the inner insulator 4. Further, the outer load - bearing surface 3 is bonded to the bearing housing 1 through the outer insulator 2. Finally, the inner load - bearing surface 5, the inner insulator 4, and the outer load - bearing surface 3 together form the load - bearing surface of a single bearing block.

[0034] A gas supply channel 6 is provided on the bearing housing 1, and a throttling device 7 is provided on the inner load - bearing surface 3. The external gas supply module inputs high - pressure gas into the bearing block through the gas supply channel 6, and the gas then flows out of the bearing block through the throttling device 7, forming a stable high - pressure gas film between the load - bearing surface of the bearing block and the carrier 8 to achieve the floating support of the carrier 8.

[0035] In this embodiment, the form of the throttling device 7 can be various throttling forms such as orifice throttling, slit throttling, and porous throttling.

[0036] Both the bearing housing 1 and the carrier 8 are grounded, and both the inner load - bearing surface 5 and the outer load - bearing surface 3 are connected to an external measurement circuit through wires. The inner load - bearing surface 5 of a single bearing block and the carrier 8 form an inner capacitor for measuring the film thickness of the bearing; the outer load - bearing surface 3 and the carrier 8 form an outer capacitor for weakening the edge effect of the inner capacitor and making the electric field of the inner capacitor evenly distributed. Both the inner and outer capacitors use the gas in the gas film as the dielectric material.

[0027] The inner load - bearing surfaces 5 and 10 of two oppositely distributed bearing blocks and the carrier 8 respectively form upper and lower inner capacitors, and the outer load - bearing surfaces 3 and 9 and the carrier 8 respectively form upper and lower outer capacitors. These four capacitors are connected to the same measurement circuit.

[0028] The working principle of the present invention is as follows: Oppositely distributed bearing blocks can both generate high - pressure gas films to support the carrier 8. Two oppositely distributed inner capacitors and the carrier 8 form a differential - structure variable - pole - pitch capacitive displacement sensor for measuring the gas film thickness of the bearing. Among them, the inner load - bearing surfaces 5 and 10 respectively serve as the two fixed plates of the capacitive displacement sensor with a differential structure, and the carrier 8 serves as the moving plate of the capacitive displacement sensor.

[0029] When the carrier 8 is at the middle position, the pole pitch d1 of the upper capacitor and the pole pitch d2 of the lower capacitor are equal, and the capacitance C1 of the upper capacitor and the capacitance C2 of the lower capacitor are equal, that is, d1 = d2 = d0, C1 = C2 = C0.

[0030] When the carrier 8 moves upward by Δd, the pole pitches of the upper and lower capacitors become respectively:

[0031]

[0032] The capacitance of the upper capacitor increases, and the capacitance of the lower capacitor decreases. The change in the total capacitance value is:

[0033]

[0034] Expanding the above formula in the form of Taylor series, we can get:

[0035]

[0036] Ignoring the high-order small terms, the relationship between the change in the total capacitance and the change in the plate spacing can be obtained as:

[0037]

[0037] Through the above formula, the relationship between the change in the gas film thickness of the bearing and the change in the total capacitance can be obtained. The change in the total capacitance can be measured by an external measurement circuit. Combining the above formula, the gas film thickness of the bearing can be finally obtained.

[0038] Embodiment 2

[0039] As Figure 3 shown, the basic structure of this embodiment is the same as that of Embodiment 1. The bearing body includes a bearing housing 1, an inner bearing surface 5, an outer bearing surface 3, an inner insulator 4, and an outer insulator 2. An air supply channel 6 is provided on the bearing housing 1, and a throttling device 7 is provided on the inner bearing surface 3. The bearing body, the carrier 8, the measurement circuit, and the air supply module form a gas static pressure bearing with self-detection ability.

[0040] The difference is that the bearing body of this embodiment has only one bearing block. The inner capacitor formed by the inner bearing surface 5 and the carrier 8 serves as a flat variable pole pitch type capacitance displacement sensor for measuring the gas film thickness, and the outer capacitor formed by the outer bearing surface 3 and the carrier 8 is still used to weaken the edge effect of the inner capacitor.

[0016] The relationship between the change in capacitance and the change in plate spacing is:

[0017]

[0041] Through the above formula, the relationship between the change in the air film thickness of the bearing and the change in capacitance can be obtained. The change in the total capacitance can be measured by an external measurement circuit. Combining the above formula, the air film thickness of the bearing can finally be obtained.

[0042] The present invention is not limited to the above optional embodiments. The above specific implementation manners are merely illustrative and guiding, rather than restrictive. Those skilled in the art can also make various forms of products under the inspiration of this specification and without departing from the scope protected by the claims of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A gas static pressure bearing with self-detection ability, characterized in that: The bearing body is composed of multiple bearing blocks. A single bearing block includes a bearing housing (1), an inner load-bearing surface (5), an outer load-bearing surface (3), an inner insulator (4), and an outer insulator (2). The bearing body, together with a carrier (8), a measurement circuit, and a gas supply module, forms a gas static pressure bearing with self-detection ability; a gas supply channel (6) is provided on the bearing housing; a throttling device (7) is provided on the inner load-bearing surface (5); the gas supply module of the bearing structure inputs high-pressure gas into the bearing through the gas supply channel (6). When the high-pressure gas flows through the throttling device (7) on the inner load-bearing surface (5), a throttling effect is generated and finally flows out of the bearing; after the gas flows out of the bearing, a high-pressure gas film is formed between the bearing load-bearing surface formed by the inner load-bearing surface (5), the inner insulator (4), and the outer load-bearing surface (3) and the carrier (8), realizing the floating support of the carrier (8).

2. The aerostatic bearing with self-detection ability according to claim 1, wherein: The form of the throttling device (7) can be various throttling forms such as orifice throttling, slit throttling, and porous throttling, etc., for throttling high-pressure gas.

3. The aerostatic bearing with self-detection ability according to claim 1, characterized in that: Both the inner load-bearing surface (5) and the outer load-bearing surface (3) are made of conductive materials and are bonded together through the inner insulator (4); the outer load-bearing surface (3) is then bonded to the bearing housing (1) through the outer insulator (2).

4. A gas static pressure bearing with self-detection ability according to claim 1, characterized in that: Both the bearing housing (1) and the carrier (8) are grounded. The inner load-bearing surface (5) and the outer load-bearing surface (3) serve as two fixed electrode plates and are both connected to an external measurement circuit through wires; the carrier (8) serves as a moving electrode plate, and the gas in the gas film is used as a dielectric material to form two inner and outer capacitors. The outer capacitor is used to weaken the edge effect of the inner capacitor and make the electric field of the inner capacitor evenly distributed.

5. The aerostatic bearing with self-detection ability according to claim 1 and 4, characterized in that: The inner load-bearing surfaces (5) and (10) of two oppositely distributed bearing blocks respectively form two upper and lower inner capacitors with the carrier (8), and the outer load-bearing surfaces (3) and (9) of two oppositely distributed bearing blocks respectively form two upper and lower outer capacitors with the carrier (8).

6. The aerostatic bearing with self-detection ability according to claims 1 and 5, characterized in that: The four capacitors in total, two upper and two lower, of two oppositely distributed bearing blocks are connected to the same measurement circuit. The two inner capacitors and the carrier (8) form a differential-structured variable pole pitch capacitive displacement sensor.

7. The aerostatic bearing with self-detection ability according to claim 1, wherein: The bearing can also have only a single bearing block, which forms a capacitive displacement sensor with the inner capacitor and the measurement circuit.

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