Multi-cavity stepped negative pressure composite vacuum glass and preparation method thereof

Abstract

This invention discloses a multi-cavity stepped negative pressure composite vacuum glass, comprising four or more tempered glass plates arranged in parallel and spaced intervals, forming three or more cavities. Adjacent glass plates are sealed at their peripheries to form independent cavities. The air pressure in each cavity decreases progressively from the outside to the inside, creating a stepped negative pressure distribution. Each cavity contains an array of support columns, with the spacing between the support columns determined according to the air pressure within that cavity. This invention also provides a method for manufacturing the multi-cavity stepped negative pressure composite vacuum glass. Through its multi-cavity stepped negative pressure design, this invention significantly reduces the pressure difference experienced by each glass plate compared to existing double-layer vacuum glass. The spacing between the support columns within the vacuum cavity is greatly increased, and the number of support columns within the vacuum cavity can be reduced by more than 80%, effectively reducing the thermal bridging effect of the vacuum glass.

Description

Technical Field

[0001] This invention relates to the fields of building energy conservation and vacuum glass technology, specifically to a vacuum glass with a multi-cavity stepped negative pressure design and its preparation method. Technical Background Vacuum glass is a new type of energy-saving glass product. Its basic structure consists of two flat glass panels forming a vacuum cavity, utilizing the vacuum layer to eliminate heat transfer through gas conduction and convection. Traditional, more mature double-layer vacuum glass consists of two tempered glass panels, spaced apart by an array of tiny support pillars. Currently, the most commonly sold 10.3mm thick single-cavity vacuum glass uses two 5mm tempered glass panels to form a 0.3mm thick vacuum cavity, with a dense array of metal support pillars spaced 15mm apart, requiring approximately 4400 support pillars per square meter.

[0002] Existing double-glazed vacuum glass suffers from the following major technical problems: First, each support column is a tiny thermal bridge channel. The thermal conductivity of stainless steel is approximately 15 W / mK, which is 20 times that of glass (approximately 0.76 W / mK). Although the total cross-sectional area of ​​the support columns accounts for only about 0.1% of the glass area, they bear 30% to 50% of the total heat transfer, severely reducing the thermal insulation performance of the vacuum glass. Second, the spacing between the vacuum chamber support columns is limited by the strength of the glass panels. Since the two panes of glass directly bear a pressure difference of one standard atmosphere (approximately 101 kPa), the spacing between the support columns is forced to remain within a dense range of 15 to 30 mm, making it difficult to reduce the number of support columns.

[0003] To address the aforementioned issues, existing technologies employ glass support columns to reduce the thermal bridging effect. However, glass support columns are brittle and require extremely high flatness during installation, making them difficult to implement in engineering applications.

[0004] Chinese patent CN201433671Y discloses a multi-cavity vacuum glass, which includes at least three glass substrates and at least one vacuum cavity space. However, the non-vacuum cavity is a normal pressure hollow cavity, and its air pressure has not been designed step by step. Moreover, the support columns are only located in the vacuum cavity, which fails to effectively solve the problems of limited spacing between support columns and severe thermal bridging effect. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the technical defects of existing vacuum glass, such as small spacing between support columns, large number of support columns, and severe thermal bridging effect, by providing a multi-cavity stepped negative pressure composite vacuum glass and its preparation method that can significantly reduce the number of support columns and reduce thermal bridging effect.

[0006] Technical solution The technical solution proposed in this invention is as follows: a multi-cavity stepped negative pressure composite vacuum glass, comprising four or more layers of tempered glass plates arranged in parallel and spaced apart, forming three or more cavities. The periphery of two adjacent glass plates is sealed to form an independent cavity. The air pressure in each cavity decreases stepwise from the outside to the inside, forming a stepped negative pressure distribution. The air pressure in the two outermost cavities is less than one standard atmosphere, which is a semi-vacuum state. The innermost cavity is a vacuum cavity with an air pressure not greater than 0.1 Pa. When the number of cavities is greater than three, the air pressure value of each transition cavity between the vacuum cavity and the outermost cavity is between the air pressure values ​​of its two adjacent cavities. Each cavity is provided with a support column array, and the spacing between each support column is set according to the air pressure of the cavity.

[0007] This invention reduces the pressure difference between the single-layer glass on both sides of the vacuum cavity from 101 kPa in the traditional scheme to 10-90 kPa by sharing the atmospheric pressure through two or more semi-vacuum cavities. After the pressure difference between each layer of glass is reduced, the spacing between the support columns in the vacuum cavity can be greatly increased, thereby reducing the number of support columns in the vacuum cavity and reducing the thermal bridging effect.

[0008] Optionally, the multi-cavity stepped negative pressure composite vacuum glass includes four tempered glass plates, namely, a first glass plate, a second glass plate, a third glass plate, and a fourth glass plate, forming three cavities, namely, a first semi-vacuum cavity, a vacuum cavity, and a second semi-vacuum cavity, respectively; the air pressure of the first semi-vacuum cavity and the second semi-vacuum cavity is 0.1~0.9 standard atmospheres.

[0009] Furthermore, the air pressure in both semi-vacuum chambers is 0.5 standard atmospheres, the thickness of the four glass plates is 4mm, the thickness of each chamber is 2mm, the spacing between the support columns in the semi-vacuum chambers is 110~130mm, and the spacing between the support columns in the vacuum chambers is 90~110mm. In this design, the maximum number of support columns per square meter in the vacuum chamber is approximately 124, which can significantly reduce the thermal bridging effect.

[0010] Optionally, the pressure in both semi-vacuum chambers is 0.1 standard atmospheres. The thickness of the first and fourth glass plates is 6 mm, the thickness of the second and third glass plates is 3 mm, and the thickness of each semi-vacuum chamber and the vacuum chamber is 2 mm. The spacing between the support columns in the two semi-vacuum chambers is 70-90 mm, and the spacing between the support columns in the vacuum chamber is 180-220 mm. In this design, the maximum number of support columns per square meter in the vacuum chamber is approximately 31, which can significantly reduce the thermal bridging effect.

[0011] Optionally, the pressure in both semi-vacuum chambers is 0.9 standard atmospheres. The thickness of the first and fourth glass plates is 3 mm, the thickness of the second and third glass plates is 6 mm, and the thickness of each semi-vacuum chamber and the vacuum chamber is 2 mm. The spacing between the support columns in the two semi-vacuum chambers is 180-220 mm, and the spacing between the support columns in the vacuum chamber is 70-90 mm. In this design, the maximum number of support columns per square meter in the vacuum chamber is approximately 205, which can significantly reduce the thermal bridging effect.

[0012] Optionally, the multi-cavity stepped negative pressure composite vacuum glass comprises five layers of tempered glass, sequentially arranged as a first glass plate, a second glass plate, a third glass plate, a fourth glass plate, and a fifth glass plate, forming four cavities, sequentially arranged as a first cavity, a second cavity, a third cavity, and a fourth cavity. Each cavity has a thickness of 2mm. The pressure in the first cavity is higher than the pressure in the second cavity, the third cavity is a vacuum cavity, and the pressure in the fourth cavity is no greater than the pressure in the second cavity. The spacing between the support columns in each cavity is 100mm~120mm. The fifth glass plate, which bears the greatest pressure difference, has the largest thickness. In this design, the number of support columns in the vacuum cavity is at most approximately 100 per square meter, which can significantly reduce the thermal bridging effect.

[0013] Optionally, the multi-cavity stepped negative pressure composite vacuum glass comprises six layers of tempered glass, sequentially arranged as a first glass plate, a second glass plate, a third glass plate, a fourth glass plate, a fifth glass plate, and a sixth glass plate, forming five cavities, sequentially arranged as a first cavity, a second cavity, a third cavity, a fourth cavity, and a fifth cavity. The air pressure in the first and fifth cavities is 0.667 standard atmospheres, the air pressure in the second and fourth cavities is 0.333 standard atmospheres, and the third cavity is a vacuum cavity with a pressure not exceeding 0.1 Pa. The thickness of each glass plate is 3 mm, and the thickness of each cavity is 2 mm. The spacing between the support columns in each cavity is 100~130 mm. In this design, the number of support columns in the vacuum cavity is at most approximately 100 per square meter, which can significantly reduce the thermal bridging effect.

[0014] Furthermore, the support column is a metal or ceramic column, and its shape is cylindrical or dumbbell-shaped or spindle-shaped, with the cross-sectional areas at both ends larger than the cross-sectional area in the middle. The support column can be of equal diameter or unequal diameter. To avoid excessive stress at the contact point with the tempered glass, the cross-sectional area at both ends of the support column can be increased. Such unequal diameter support columns can reduce the stress concentration at the contact point with the glass. The dimensions of the support column are set according to the pressure difference and spacing of the cavity.

[0015] Furthermore, the glass plates are sealed together along the periphery by a sealing material, the width of which is 5mm to 15mm. The sealing material is at least one of low melting point glass powder, metal solder, or polymer sealant.

[0016] Furthermore, a getter is provided inside the vacuum chamber.

[0017] This invention also provides a method for preparing multi-cavity stepped negative pressure composite vacuum glass, comprising: Step 1: Provide a tempered glass plate with four or more layers and clean and dry it; Step 2: Arrange the support column array between the glass plates at a preset interval, and place the getter on any one of the two glass plates that are to form a vacuum cavity. Step 3: Seal and connect each glass plate along its perimeter to form an independent cavity, and leave an air extraction port on the sealed perimeter of each cavity; Step 4: Evacuate each semi-vacuum chamber to its target pressure step by step, then seal the evacuation port. Step 5: After evacuating the vacuum chamber to a depth below 0.1 Pa, seal the evacuation port and simultaneously activate the getter in the vacuum chamber to complete the preparation.

[0018] Optionally, tempered glass panels can be combined in pairs to form a single insulated glass unit with supporting columns, and then these insulated glass units can be fabricated into a multi-cavity stepped negative pressure composite vacuum glass unit with a semi-vacuum cavity and a vacuum cavity.

[0019] Optionally, in step one, deionized water, anhydrous ethanol, isopropanol, or acetone, or a combination of two or more thereof, may be used for cleaning to remove dust, fingerprints, or grease from the glass surface.

[0020] Optionally, steps two and three can be combined into one step. The pre-formed sealing material with venting ports is arranged on the edge of each glass plate, and a support column array is arranged at a preset interval. A getter is placed on either of the two middle glass plates, and the glass plates are connected by heating and / or pressurizing to facilitate subsequent venting and sealing.

[0021] Furthermore, in step four, all cavities are evacuated simultaneously. When each semi-vacuum cavity reaches the target pressure, the evacuation port of the corresponding semi-vacuum cavity is closed. When the pressure inside the vacuum cavity is lower than 0.1 Pa, the evacuation port of the vacuum cavity is closed.

[0022] Beneficial effects (mechanical verification) Taking a four-layer, three-cavity structure as an example, when the air pressure in the outer semi-vacuum cavity is set to 0.5 standard atmospheres (approximately 50.7 kPa), the pressure difference borne by the four layers of glass is 0.5 atm. Mechanical calculations using the theory of simply supported elastic thin plates show that with a glass thickness of 4 mm and a support column spacing of 110 mm, the maximum deflection is only 0.07 mm (far less than the plate thickness of 4 mm and the cavity thickness of 2 mm), and the maximum bending stress is 11.0 MPa (far less than the design strength of tempered glass of 84 MPa), resulting in a safety factor of over 7.6. Each column bears a load of approximately 613 N, and the contact stress at the end of the support column can be controlled within 84 MPa. The required end diameter is approximately 3.0 mm, and dumbbell-shaped support columns (φ3.0 mm at the end and φ1.0 mm in the middle) can be used, easily fitting into a 2 mm thick semi-vacuum cavity with a 110 mm spacing.

[0023] Compared to traditional double-layer vacuum glass (15mm spacing, 4400 support columns / m²), the 4-layer, 3-cavity, 0.5atm solution of this invention requires only approximately 249 support columns / m² (166 in the semi-vacuum cavity + 83 in the vacuum cavity), reducing the number of support columns by more than 94%. If only the thermal bridging effect of the support columns within the vacuum cavity is considered, the 83 support columns represent a significant reduction compared to 4400, resulting in a substantial improvement in thermal insulation performance.

[0024] (1) Compared with the prior art, the air pressure in all cavities of the present invention decreases stepwise from the outer layer to the inner layer to form a stepped negative pressure, so that each layer of glass shares the atmospheric pressure, thereby reducing the number of support columns in the vacuum cavity.

[0025] (2) The spacing between the support columns of each cavity is set according to the difference in air pressure in the cavity to achieve a balance between structural safety and minimizing thermal bridges.

[0026] (3) The thermal bridging effect is a significant drawback of traditional double-layer vacuum glass. More than 4,000 metal support columns directly penetrate the vacuum layer, forming a large number of heat conduction channels, which greatly reduces the heat insulation effect of the vacuum layer. Compared with the existing double-layer vacuum glass, the number of support columns in the vacuum cavity of the present invention is much smaller, the thermal bridging effect is significantly reduced, and the safety redundancy is greatly improved. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the cross-section of the vacuum glass with a 4-layer, 3-cavity structure of the present invention.

[0028] Figure 2 This is a schematic diagram of the cross-section of the vacuum glass structure with 5 layers and 4 cavities of the present invention.

[0029] Figure 3 This is a schematic diagram of the cross-section of the vacuum glass structure with 6 layers and 5 cavities of the present invention.

[0030] Figure 4 This is a schematic diagram of the shape of the support column of the present invention, wherein... Figure 4 (a) is a typical cylindrical support column. Figure 4 (b) is a dumbbell-shaped support column. Figure 4 (c) is a spindle-shaped support column.

[0031] Figure 5 This is a process flow diagram of the vacuum glass preparation method of the present invention.

[0032] Wherein, 1-first glass plate, 2-second glass plate, 3-third glass plate, 4-fourth glass plate, 5-fifth glass plate, 6-sixth glass plate, 9-support column, 10-vacuum cavity, 11-sealing layer, 20-first semi-vacuum cavity, 30-second semi-vacuum cavity. Detailed Implementation

[0033] The following description, in conjunction with the accompanying drawings and embodiments, provides a more detailed description of a vacuum glass employing a multi-cavity stepped negative pressure design and its preparation method.

[0034] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance; those skilled in the art can understand the specific meaning of the above terms in this invention as appropriate.

[0035] The multi-cavity stepped negative pressure in this invention means that there are at least 3 cavities, each with negative pressure, and the air pressure between adjacent cavities is different. The air pressure in each cavity of the vacuum glass gradually decreases from the outside to the inside. The inside and outside in this invention are described with the vacuum cavity as the center reference. The vacuum cavity is inside, and the cavities or glass plates farther away from the vacuum cavity are further out.

[0036] The semi-vacuum cavity of this invention is a cavity with a pressure between standard atmospheric pressure and vacuum. Its internal pressure is lower than the external atmospheric pressure but higher than the pressure inside a vacuum cavity. The pressure inside the vacuum cavity is no greater than 0.1 Pa.

[0037] Mechanical Design Principles In various embodiments of the present invention, the selection of the support column spacing and glass thickness is based on the following mechanical verification criteria: (1) The maximum deflection and maximum bending stress at the center of the glass plate are calculated using the small deflection theory of simply supported elastic thin plates. The formula is as follows: (1) (2) in, α = 0.0443, the deflection coefficient; p = 0.22, the uniformly distributed load (Pa); a = 70 GPa, the elastic modulus; t = 0.22, the Poisson's ratio. σ_design = 84MPa, which is the design strength of the tempered glass; p_atm = 101325Pa, which is the standard atmospheric pressure.

[0038] (2) The maximum bending stress of the glass plate shall not exceed 84 MPa of the design strength of tempered glass (safety factor ≥ 2.5). (3) The maximum deflection of the glass plate shall not exceed half the thickness of the plate, and shall not exceed the thickness of the corresponding cavity; (4) The contact stress at the end of the support column shall not exceed the allowable compressive stress of 84 MPa on the surface of the tempered glass. Based on this, determine the minimum diameter required at the end of the support column.

[0039] (5) The axial compressive stress (F / cross-sectional area of ​​the rod) of the support column shall not exceed the allowable stress of stainless steel 200MPa (safety factor K=2.5), and the diameter of the rod shall not exceed the thickness of the cavity in which it is located.

[0040] Example 1: 4-layer 3-cavity structure (semi-vacuum cavity pressure 0.5 atm, for equalization scheme) like Figure 1 As shown, the multi-cavity stepped negative pressure composite vacuum glass provided in this embodiment includes four layers of tempered glass plates stacked flat, namely the first glass plate 1, the second glass plate 2, the third glass plate 3 and the fourth glass plate 4. The adjacent glass plates form independent cavities, namely the first semi-vacuum cavity 20, the vacuum cavity 10 and the second semi-vacuum cavity 30, respectively.

[0041] In these three cavities, vacuum cavity 10 is a vacuum with a pressure not exceeding 0.1 Pa; the pressure in the first semi-vacuum cavity 20 and the second semi-vacuum cavity 30 can be selected within the range of 0.1 to 0.9 standard atmospheres, and in this embodiment, it is specifically selected as 0.5 standard atmospheres (approximately 50.7 kPa), which is a semi-vacuum state. Each of the three cavities, the first semi-vacuum cavity 20, vacuum cavity 10, and second semi-vacuum cavity 30, is equipped with an array of support columns 9, and the thickness of each cavity is 2 mm. The spacing between the support columns in vacuum cavity 10, semi-vacuum cavities 20, and 30 is 110 mm.

[0042] Total thickness: 4+2+4+2+4+2+4=22mm (including vacuum cavity). Surface density: approximately 40kg / m².

[0043] Mechanical calculations: The pressure difference between each glass layer is 0.5 atm (50.7 kPa), the spacing between support columns is 110 mm, and the glass thickness is 4 mm. Calculations show the maximum deflection is 0.07 mm (< 4 mm plate thickness, < 2 mm cavity thickness, passed); the maximum bending stress is 11.0 MPa (< 84 MPa design strength, safety factor 7.6, passed); the load per column is 613 N; and the minimum required diameter at the end of the support column is 3.0 mm.

[0044] Support column configuration: The support columns in vacuum chamber 10 and semi-vacuum chambers 20 and 30 are dumbbell-shaped stainless steel support columns with an end diameter of 3.0mm, a middle section thin rod diameter of 1.0mm, and a height of 2.0mm.

[0045] Support column count: Approximately 83 (1000 / 110)² support columns are present in the semi-vacuum chambers, totaling 166 in both semi-vacuum chambers; approximately 83 support columns are present in the vacuum chambers. The total number of support columns is approximately 249 / m², a reduction of approximately 94.3% compared to traditional double-layer vacuum glass (4400 / m²). If only the thermal bridging effect caused by the support columns within the vacuum chambers is considered, the thermal bridging effect of the vacuum glass of this invention is significantly smaller than that of traditional double-layer vacuum glass.

[0046] Example 2: 4-layer 3-cavity structure (semi-vacuum chamber pressure 0.1 atm, high pressure differential scheme) This embodiment has the same structure as Embodiment 1, except that the air pressure in both the first semi-vacuum chamber 20 and the second semi-vacuum chamber 30 is 0.1 atmospheres (approximately 10.1 kPa). The thickness of the first glass plate 1 and the fourth glass plate 4 (outer glass) is 6 mm, and the thickness of the second glass plate 2 and the third glass plate 3 (inner glass) is 3 mm. The thickness of each cavity is 2 mm.

[0047] Mechanical calculations: The outer glass layer experiences the greatest pressure difference, 1 - 0.1 = 0.9 atm (91.2 kPa), with a support column spacing of 80 mm and a glass thickness of 6 mm. Maximum deflection: 0.01 mm (passed); maximum bending stress: 4.7 MPa (safety factor 17.9, passed); load per column: 584 N; required end diameter: 3.0 mm. The inner glass layer experiences a pressure difference of 0.1 atm (10.1 kPa), with a support column spacing of 80 mm and a glass thickness of 3 mm. Maximum deflection: 0.01 mm (passed); maximum bending stress: 2.1 MPa (passed). The vacuum cavity experiences a pressure difference of 0.1 atm (10.1 kPa), with a support column spacing of 200 mm and a glass thickness of 3 mm. Maximum deflection: 0.38 mm (< cavity thickness 2 mm, passed); maximum bending stress: 12.9 MPa (passed).

[0048] Number of support columns: Approximately 156 (1000 / 80)² support columns per square meter for the semi-vacuum chambers, totaling 312 for the two semi-vacuum chambers; approximately 25 support columns per square meter for the vacuum chambers. Total: Approximately 337 support columns per square meter. Total thickness: 6+2+3+2+3+2+6=24mm. This solution is suitable for extreme climate regions; the thicker outer glass layer provides higher impact resistance.

[0049] Example 3: 4-layer 3-cavity structure (semi-vacuum chamber pressure 0.9 atm, weak negative pressure scheme) This embodiment has the same structure as Embodiment 1, except that the air pressure in both the first semi-vacuum chamber 20 and the second semi-vacuum chamber 30 is 0.9 standard atmospheres (approximately 91.2 kPa). The thickness of the first glass plate 1 and the fourth glass plate 4 (outer glass) is 3 mm, and the thickness of the second glass plate 2 and the third glass plate 3 (inner glass) is 6 mm. The thickness of each cavity is 2 mm.

[0050] Mechanical calculations: The inner glass layer bears the greatest pressure difference, approximately 0.9 - 0 ≈ 0.9 atm (91.2 kPa), with a support column spacing of 80 mm and a glass thickness of 6 mm. The outer glass layer bears a pressure difference of 1 - 0.9 = 0.1 atm (10.1 kPa), with a support column spacing of 80 mm and a glass thickness of 3 mm. This scheme is symmetrical to Example 2, with the same mechanical calculation parameters, only the thicknesses of the inner and outer glass layers are reversed.

[0051] Number of support columns: Same as in Example 2, approximately 337 per m². Total thickness: 24 mm. This solution is suitable for applications where the vacuum level of the semi-vacuum chamber is not critical; it can be achieved with rough vacuuming, resulting in low manufacturing costs.

[0052] Example 4: 5-layer 4-cavity structure (semi-vacuum cavity asymmetric arrangement) like Figure 2 As shown, the multi-cavity stepped negative pressure composite vacuum glass provided in this embodiment comprises five layers of tempered glass plates stacked flush, namely, first glass plate 1, second glass plate 2, third glass plate 3, fourth glass plate 4, and fifth glass plate 5. The five glass plates form four cavities, numbered from the first cavity to the fourth cavity, each with a thickness of 2 mm. The third cavity is a vacuum cavity (pressure not exceeding 0.1 Pa), while the first, second, and fourth cavities are semi-vacuum cavities. The pressure in each semi-vacuum cavity decreases progressively from the outside to the inside.

[0053] In this embodiment, the pressure distribution is as follows: 1 standard atmosphere → first cavity (0.7 standard atmospheres) → second cavity (0.35 standard atmospheres) → third cavity (vacuum) → fourth cavity (0.35 standard atmospheres) → 1 standard atmosphere. The pressure difference between each glass layer is: first glass plate 0.3 atm, second glass plate 0.35 atm, third glass plate 0.35 atm, fourth glass plate 0.35 atm, and fifth glass plate 0.65 atm. Since the number of layers is odd, the number of semi-vacuum cavities on both sides of the vacuum cavity is unequal. The fifth glass plate, located on the outermost side, bears a relatively large pressure difference. Therefore, in this embodiment, the fifth glass plate uses a thicker 5mm tempered glass, the first and second glass plates use 4mm tempered glass, and the third and fourth glass plates use 3mm tempered glass.

[0054] Mechanical calculations: The outermost first cavity (0.3 atm pressure difference, 4mm glass, 120mm support column spacing) has a maximum deflection of 0.09mm, a maximum bending stress of 9.3MPa, a load per column of 438N, and an end diameter of 2.6mm. The second cavity (0.35 atm pressure difference, 4mm glass, 120mm) has a maximum deflection of 0.11mm, a maximum bending stress of 10.9MPa, a load per column of 511N, and an end diameter of 2.8mm. The third cavity (vacuum, 0.35 atm pressure difference, 3mm glass, 120mm) has a maximum deflection of 0.17mm, a maximum bending stress of 16.3MPa (safety factor 5.2), a load per column of 511N, and an end diameter of 2.8mm. The fourth cavity (0.35 atm pressure difference, 3mm glass, 120mm) has the same parameters as the third cavity. The fifth glass plate (0.65 atm pressure difference, 5mm glass, 120mm) has a maximum deflection of 0.07mm and a maximum bending stress of 10.9MPa.

[0055] The support columns are dumbbell-shaped stainless steel, with a diameter of ≤2mm for each cavity. Support column count: Approximately 70 (1000 / 120)² support columns per cavity, totaling approximately 280 columns / m² for all four cavities, a reduction of approximately 93.6% compared to traditional double-layer vacuum glass (4400 columns / m²). Total thickness: 4+2+4+2+3+2+3+2+5=27mm.

[0056] In this design, the pressure in the semi-vacuum chamber decreases gradually from the outside to the inside. Looking outward from the vacuum chamber, there are two outermost chambers. One outermost semi-vacuum chamber has a higher pressure (0.7 atm), thus bearing less external pressure. Therefore, a thinner outer glass plate (4mm) is used to protect the inner low-pressure semi-vacuum chamber and the vacuum chamber. The other outermost semi-vacuum chamber maintains a pressure of 0.35 atm, thus bearing greater external pressure (0.65 atm). Therefore, a thicker outer glass plate (5mm) is used to effectively buffer external impact forces. This arrangement ensures equal pressure difference on both sides of the vacuum chamber (0.35 atm on the outside and 0.35 atm on the inside), guaranteeing controllable stress on the vacuum chamber. This design is suitable for applications requiring high mechanical safety and impact resistance.

[0057] Example 5: 6-layer, 5-cavity structure (uniform air pressure distribution scheme) like Figure 3 As shown, the multi-cavity stepped negative pressure composite vacuum glass provided in this embodiment comprises six layers of tempered glass plates stacked flush, numbered from the first glass plate 1 to the sixth glass plate 6, each with a thickness of 3 mm. The six glass plates form five cavities, numbered from the first cavity to the fifth cavity. The air pressure in the first and fifth cavities is 0.667 standard atmospheres, the air pressure in the second and fourth cavities is 0.333 standard atmospheres, and the third cavity is a vacuum cavity (air pressure not exceeding 0.1 Pa).

[0058] Each cavity is 2mm thick, with support columns spaced 100mm-130mm apart. Each glass layer withstands a pressure difference of 0.333 atm (33.8 kPa), with a maximum deflection of 0.08mm, a maximum bending stress of 9.2 MPa (safety factor 9.1), and a maximum load of 571 N per column (when the support column spacing is 130mm). The column has an end diameter of 3.0mm and a rod diameter of 2.0mm. The number of support columns is approximately 100 per cavity per square meter, totaling approximately 500 columns per m² for all five cavities. The total thickness is 31mm, and the surface density is approximately 45kg / m².

[0059] This design, with its 6 layers and 5 cavities, ensures that the stress on each layer of glass is completely uniform, making it the most balanced engineering solution.

[0060] It should be emphasized that the above technical solutions use the rather general term "approximately" when referring to the number of support columns. This is mainly because the number of support columns must be a natural number. The number of support columns calculated per square meter based on the minimum support column spacing (i.e., maximum support column density) of the vacuum cavity in each solution mostly contains decimals. In this invention, the number of support columns per square meter is obtained by rounding up.

[0061] The vacuum glass of this invention can be symmetrical, for example, using 4 layers (e.g., Figure 1As shown), 6 floors (as shown) Figure 3 Vacuum glass is made of 8 layers of glass (as shown) and 8 layers of glass plates, with the vacuum chamber 10 in the middle; it can also be asymmetrical, for example, 5 layers (as shown). Figure 2 Vacuum glass, as shown), consists of 7 and 9 layers of glass. The vacuum cavity 10 may not be in the center, but this does not affect the characteristic of stepped negative pressure between the cavities in their structure.

[0062] Support column design All support columns in this invention are cylindrical, dumbbell-shaped, or spindle-shaped (e.g., Figure 4 As shown): The diameters of the two ends are determined by the contact stress on the glass surface (84 MPa) and the load per column; the diameter of the middle rod is determined by the yield strength of the rod material (200 MPa for stainless steel), and the rod diameter does not exceed the thickness of the cavity to ensure that the rod can be installed in the cavity. The diameters of the two ends can be larger than the cavity thickness because the ends are located on the contact surface of the glass plate rather than inside the cavity, and the contact indentation between the ends and the glass surface is embedded in the glass surface, without occupying cavity space. The uniform cavity thickness of 2 mm design allows dumbbell-shaped support columns of the same specification (end diameter approximately 3 mm, rod diameter 2 mm, height 2 mm) to be applied to all cavities, only requiring adjustment of the support column spacing according to the pressure difference of each cavity. Of course, this invention does not exclude the use of cylindrical and spindle-shaped support columns.

[0063] Sealants and getters The glass plates are sealed together along their perimeter using a sealing material, with the sealing layer 11 having a width of 5mm to 15mm. The sealing material can be low-melting-point glass powder, metal solder, or polymer sealant. A getter can be placed inside the vacuum chamber 10 as needed to maintain a long-term vacuum.

[0064] Example 6: Preparation Method like Figure 5 As shown, the method for preparing multi-cavity stepped negative pressure composite vacuum glass provided by the present invention includes the following steps: Step 1: Select a tempered glass panel with four or more layers according to the design requirements, and clean and dry it. One or more combinations of deionized water, anhydrous ethanol, isopropanol, or acetone can be used for cleaning to remove dust, fingerprints, or grease from the glass surface.

[0065] Step 2: Arrange the support column array between the glass plates at a preset interval. The spacing of the support columns 9 is determined by mechanical calculation based on the air pressure of the cavity and the thickness of the glass plates. Place a getter on either of the two glass plates (located inside the vacuum cavity 10) that will form the vacuum cavity 10.

[0066] Step 3: Seal each glass plate along its perimeter with sealing material to form an independent cavity, and leave an evacuation port on the sealed perimeter of each cavity. The sealing method can be to sinter low-melting-point glass powder at 450~500℃, or to use polymer sealant cured at room temperature.

[0067] Step 4: Evacuate each semi-vacuum chamber step by step to its target pressure, then seal the evacuation port. All chambers can be evacuated simultaneously. Once each semi-vacuum chamber reaches its target pressure, the evacuation device for that chamber is shut off and the evacuation port is sealed.

[0068] Step 5: Evacuate the vacuum chamber 10 to a depth below 0.1 Pa, while activating the getter in the vacuum chamber 10, and then seal the evacuation port to complete the preparation.

[0069] In one alternative approach, tempered glass sheets can be first combined in pairs to form semi-finished insulated glass units with support columns, and then these semi-finished units can be assembled into multi-chamber vacuum glass. This method divides the production process into a standardized manufacturing stage and an assembly and evacuation stage, which is beneficial for mass production.

[0070] For example, to manufacture a vacuum glass composed of four layers of glass, a batch of single-cavity insulated glass units with support columns can be produced in one section or factory area. These single-cavity insulated glass units all have evacuation ports. This batch of single-cavity insulated glass units is then transferred to the next section or factory area, where two single-cavity insulated glass units are stacked together, with support columns, sealing material, and evacuation ports in between. Once the two single-cavity insulated glass units are connected to form a three-cavity glass assembly, each cavity is evacuated. Multiple vacuum pumps can be used to evacuate each cavity to a predetermined pressure until the pressure in each cavity reaches the predetermined pressure. Then, the evacuation ports of each cavity are sealed, and finally, the getter placed inside the vacuum cavity is activated.

[0071] In another optional embodiment, after cleaning the glass plates, the first glass plate is placed first, and the support column array within the first cavity is arranged at a preset interval. Then, a pre-fabricated sealing material preform is placed on this glass plate, which can cover the edge of the glass plate by 5mm to 15mm, and an extraction port is left in the preform. Next, the second glass plate is aligned with the first glass plate, and the operation on the first glass plate is the same, placing the support column array and the sealing material preform. This process is repeated until the last glass plate is placed. It should be noted that a getter is placed on either of the two glass plates that are to form the vacuum cavity 10 (usually the one that was facing down during glass manufacturing). The sealing material is activated by heating and / or pressurizing, thereby connecting all the glass plates to facilitate subsequent extraction and sealing.

[0072] In an optional embodiment, a vacuum pump with multiple suction ports is used for evacuation. Each suction port is connected to a vacuum gauge and can be controlled independently. They correspond to semi-vacuum chambers and vacuum chambers with different pressures, respectively. During initial evacuation, multiple suction ports evacuate all chambers simultaneously. When each semi-vacuum chamber reaches the target pressure, the suction port of the corresponding semi-vacuum chamber is closed, and the corresponding exhaust port is sealed. When the pressure in the vacuum chamber is lower than 0.1 Pa, the suction port of the corresponding vacuum chamber is closed, and the exhaust port is sealed.

[0073] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-cavity stepped negative pressure composite vacuum glass, comprising four or more layers of tempered glass plates arranged in parallel and spaced apart, forming three or more cavities, characterized in that, The perimeter of two adjacent glass plates is sealed to form an independent cavity. The air pressure in each cavity decreases gradually from the outside to the inside, forming a stepped negative pressure distribution. The air pressure in the two outermost cavities is less than one standard atmosphere, which is a semi-vacuum state. The innermost cavity is a vacuum cavity with an air pressure of no more than 0.1 Pa. When there are more than 3 cavities, the air pressure value of each transition cavity between the vacuum cavity and the outermost cavity is between the air pressure values ​​of the two adjacent cavities. Each cavity is equipped with an array of support columns, and the spacing between the support columns is set according to the air pressure of the cavity.

2. The vacuum glass as described in claim 1, characterized in that, It includes four tempered glass plates, namely, the first glass plate (1), the second glass plate (2), the third glass plate (3) and the fourth glass plate (4), forming three cavities, namely, the first semi-vacuum cavity (20), the vacuum cavity (10) and the second semi-vacuum cavity (30); the air pressure of the first semi-vacuum cavity (20) and the second semi-vacuum cavity (30) is 0.1~0.9 standard atmospheres.

3. The vacuum glass as described in claim 2, characterized in that, The air pressure in both semi-vacuum chambers is 0.5 standard atmospheres, the thickness of the four glass plates is 4mm, the thickness of each chamber is 2mm, the spacing between the support columns in the semi-vacuum chamber is 110~130mm, and the spacing between the support columns in the vacuum chamber is 90~110mm.

4. The vacuum glass as described in claim 1, characterized in that, It includes five tempered glass plates, namely, the first glass plate (1), the second glass plate (2), the third glass plate (3), the fourth glass plate (4), and the fifth glass plate (5), forming four cavities, namely, the first cavity, the second cavity, the third cavity, and the fourth cavity; the thickness of each cavity is 2mm, the pressure in the first cavity is higher than the pressure in the second cavity, the third cavity is a vacuum cavity, and the pressure in the fourth cavity is no greater than the pressure in the second cavity; the spacing between the support columns in each cavity is 100mm~120mm; the fifth glass plate (5), which bears the greatest pressure difference, has the largest thickness.

5. The vacuum glass as described in claim 1, characterized in that, It comprises six layers of tempered glass, namely, the first glass plate (1), the second glass plate (2), the third glass plate (3), the fourth glass plate (4), the fifth glass plate (5), and the sixth glass plate (6), forming five cavities, namely, the first cavity, the second cavity, the third cavity, the fourth cavity, and the fifth cavity; the air pressure in the first cavity and the fifth cavity is 0.667 standard atmospheres, the air pressure in the second cavity and the fourth cavity is 0.333 standard atmospheres, and the third cavity is a vacuum cavity; the thickness of each glass plate is 3mm, the thickness of each cavity is 2mm, and the spacing between the support columns is 100~130mm.

6. The vacuum glass according to any one of claims 1 to 5, characterized in that, The support column (9) is a metal column or a ceramic column, and its shape is cylindrical or dumbbell-shaped or spindle-shaped with the cross-sectional area at both ends being larger than the cross-sectional area in the middle section. The size of the support column is set according to the pressure difference and spacing of the cavity.

7. The vacuum glass according to any one of claims 1 to 5, characterized in that, Each of the glass plates is sealed and connected along the periphery by a sealing material. The width of the sealing layer (11) is 5mm to 15mm. The sealing material is at least one of low melting point glass powder, metal solder or polymer sealant.

8. The vacuum glass according to any one of claims 1 to 5, characterized in that, A getter is provided inside the vacuum chamber (10).

9. The method for preparing vacuum glass according to any one of claims 1 to 8, characterized in that, include: Step 1: Provide a tempered glass plate with four or more layers and clean and dry it; Step 2: Arrange the support column array between the glass plates at a preset interval, and place the getter on any one of the two glass plates that are to form the vacuum cavity (10); Step 3: Seal and connect each glass plate along its perimeter to form an independent cavity, and reserve an air extraction port on the sealed perimeter of each cavity; Step 4: Evacuate each semi-vacuum chamber to its target pressure step by step and then seal the evacuation port. Step 5: After evacuating the vacuum chamber (10) to a depth of less than 0.1 Pa, seal the evacuation port and activate the getter in the vacuum chamber (10) to complete the preparation.

10. The preparation method according to claim 9, characterized in that, In step four, all cavities are evacuated simultaneously. Once each semi-vacuum cavity reaches the target pressure, the evacuation port of the corresponding semi-vacuum cavity is closed. When the pressure inside the vacuum cavity is lower than 0.1 Pa, the evacuation port of the vacuum cavity is closed.

Images