Constant temperature control method and device for slow fluctuation

Abstract

The invention discloses a slow-fluctuation constant-temperature control method and device, and belongs to the technical field of constant-temperature control, the slow-fluctuation constant-temperature control device comprises a circuit part and a structure part, the circuit part comprises a temperature control module, and the structure part is of a multi-layer nested structure and sequentially comprises a heat preservation layer, a heating area, a heating groove, a heat insulation layer, a temperature storage groove and a target temperature control area from outside to inside. The target temperature control area is a temperature control target point, the heat preservation layer is used for temperature isolation between the whole constant temperature control device and the external environment, and the heating groove is made of a material with a high heat capacity ratio. The heat insulation layer is used for reducing the transmission speed of heat of the heating groove to the temperature storage groove and meanwhile used for conducting heat preservation on the temperature storage groove, and the temperature storage groove is used for storing heat conducted from the outside and providing temperature balance for a target temperature area. According to the constant temperature control method and the constant temperature control device, periodic rapid temperature fluctuation generated by the temperature control module can be effectively attenuated through a unique three-layer progressive heat buffering and filtering structure of the heating tank, the heat insulation layer and the temperature storage tank.

Description

Technical Field

[0001] This invention belongs to the field of constant temperature control technology, and particularly relates to a method and device for slow-fluctuation constant temperature control. Background Technology

[0002] Some devices or products with temperature characteristics often improve their temperature stability by placing them in a temperature-stable environment. This is especially important when temperature stability affects their core performance indicators. For example, frequency control products such as oven-controlled crystal oscillators and atomic clocks are significantly affected by temperature changes in the stability of their output signals, and stability is precisely their core performance indicator. Therefore, temperature control is crucial.

[0003] Specifically, the temperature characteristics of a cryogenic crystal oscillator (atomic clock) manifest in the output signal fluctuating with the temperature of the cryogenic bath. Although the absolute value of the fluctuation is very small, even reaching E⁻¹⁰ or smaller, these fluctuations have a particularly significant impact on stability assessment using Allan variance. Practice shows that when the period of a frequency signal fluctuation is T, the frequency stability deteriorates significantly at T / 3 on its Allan variance curve. These effects can be clearly demonstrated through simulation calculations.

[0004] Therefore, a temperature control effect with low fluctuation and a long fluctuation period (slow fluctuation) plays a significant role in improving the stability performance of a temperature-controlled crystal oscillator (atomic clock). Through this invention, the frequency stability of the temperature-controlled crystal oscillator from 3s to 1000s can be improved by more than 10 times.

[0005] In miniature temperature control structures, due to size limitations, the structure only has heating capabilities and no cooling capabilities. Whether affected by external temperature changes or internal fluctuations, temperature stability is maintained through heating. While heating can keep the average temperature near the setpoint, the switching or power adjustment processes of the temperature control elements (such as heaters) and the delay in sensor feedback inevitably introduce periodic, microscopic, rapid temperature fluctuations (i.e., "fast fluctuations") into the target area. Even if the absolute value of these fluctuations is small, they still constitute significant interference for sensitive components that require extreme stability. Furthermore, slow changes in the external ambient temperature (such as diurnal temperature variations) can penetrate the insulation layer, causing a slow, follow-through drift in the temperature of the target area.

[0006] Therefore, there is an urgent need for a highly stable constant temperature control scheme that can significantly attenuate the rapid temperature fluctuations generated by the internal control loop in principle, while responding extremely slowly to changes in the external environment, thereby achieving truly "slow fluctuations" or even close to "no fluctuations" in the target area.

[0007] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a method and apparatus for slow-fluctuation constant temperature control. Through a unique three-layer progressive thermal buffering and filtering structure—a heating tank, an insulation layer, and a storage tank—the periodic rapid temperature fluctuations generated by the temperature control module can be effectively attenuated. Heat is initially accumulated and smoothed in the heating tank, and then slowly transferred to the storage tank for secondary energy storage and equalization via a highly insulating layer. Ultimately, the fluctuation amplitude within the target temperature control zone is greatly suppressed. This makes the temperature in the target area almost insensitive to rapid changes in the external environment, exhibiting only extremely delayed and weak responses to slow environmental changes, achieving the core objective of "slow fluctuation" and providing a near-ideal thermal environment for high-precision devices.

[0009] To achieve the above objectives, the present invention proposes a slow-fluctuation constant temperature control device, which includes a circuit part and a structural part, wherein the circuit part includes a temperature control module.

[0010] The structure is a multi-layered nested structure, consisting of, from the outside in, a heat insulation layer, a heating zone, a heating tank, a heat insulation layer, a heat storage tank, and a target temperature control zone.

[0011] The target temperature control zone is the temperature control target point.

[0012] The insulation layer isolates the entire temperature control device from the external environment in terms of temperature.

[0013] The heating module is connected to the heating tank through direct contact.

[0014] The heating tank is made of a material with a high heat capacity ratio.

[0015] The insulation layer is used to reduce the rate at which heat is transferred from the heating tank to the storage tank, so that the temperature of the storage tank is significantly lower than that of the heating tank. At the same time, it is used to keep the storage tank warm and isolate it from external temperature changes.

[0016] The heat storage tank is used to store heat conducted in from the outside and to provide temperature balance for the target temperature zone.

[0017] The target temperature control zone is used to house components that require constant temperature.

[0018] Preferably, the temperature control module includes a temperature control circuit, several heating modules, and several temperature sensors.

[0019] The heating module and temperature sensor are both evenly distributed within the heating zone.

[0020] Preferably, the heating module uses a low-frequency, medium / low-power power transistor, which is either a transistor or a field-effect transistor. The heating module's structure tightly integrates the heating part of the power transistor with the structure to be heated.

[0021] Preferably, the heating module uses multiple power transistors to generate heat together, and the layout adopts a symmetrical structure.

[0022] Preferably, the temperature sensor is responsible for collecting the temperature of the heating bath, and is tightly coupled with the heating module, and feeds back the collected temperature to the temperature control circuit for negative feedback control.

[0023] Preferably, the temperature control circuit adopts a proportional-integral circuit form to receive temperature information fed back by the temperature sensor, and controls the heating module to perform high-power heating, low-power heating, and stop heating by comparing the received temperature information with a set threshold.

[0024] Preferably, the interior of the insulation layer is circular.

[0025] Preferably, the heating tank is made of copper or aluminum.

[0026] The insulation layer material is felt or polyethylene foam.

[0027] The material of the storage tank is the same as that of the heating tank.

[0028] Preferably, the component requiring constant temperature is one or more of the crystal resonator on the crystal oscillator, the physical components of the crystal oscillator and the atomic clock.

[0029] A slow-fluctuation constant temperature control method is applied to the aforementioned constant temperature control device, and the constant temperature control method is as follows:

[0030] At the start of operation, the temperature control module begins to work. When the temperature information returned by the temperature sensor is much lower than the set threshold, the temperature control circuit controls the heating module to start heating at high power. As the temperature rises, the temperature information returned by the temperature sensor gradually approaches the set threshold. The temperature control circuit then controls the heating module to gradually reduce the heating power until equilibrium is reached. At this point, the temperature curve on the temperature sensor is the first sawtooth waveform.

[0031] By controlling and shortening the time constant, and through the coordination of circuit parameters and structure, the first sawtooth waveform curve is initially adjusted into a second sawtooth waveform, the period of which is relatively shorter than that of the first sawtooth waveform.

[0032] Heat accumulates in the heating tank, gradually increasing the temperature towards the set temperature, while the amplitude of the second sawtooth waveform decreases.

[0033] The heat in the heating tank is continuously conducted inward, and the temperature of the storage tank rises slowly until it reaches the set temperature and enters a stable state. After reaching stability, the temperature fluctuation of the storage tank decreases.

[0034] The slow-fluctuation constant temperature control method and device proposed in this invention can bring the following beneficial effects:

[0035] 1. The constant temperature control method and device of this invention utilizes a unique three-layer progressive thermal buffering and filtering structure—a heating tank, an insulation layer, and a storage tank—to effectively attenuate the periodic and rapid temperature fluctuations generated by the temperature control module. Heat is initially accumulated and smoothed in the heating tank, then slowly transferred to the storage tank for secondary energy storage and equalization via a highly insulating layer. Ultimately, the fluctuation amplitude within the target temperature control zone is greatly suppressed. This makes the temperature in the target area almost insensitive to rapid changes in the external environment, exhibiting only extremely delayed and weak responses to slow environmental changes, achieving the core objective of "slow fluctuation" and providing a near-ideal thermal environment for high-precision devices.

[0036] 2. This invention places the active temperature control components (heating module, temperature sensor, temperature control circuit) of the constant temperature control method and device in the outer heating zone, providing dual physical and thermal isolation from the innermost target temperature control zone. Microscopic fluctuations such as power regulation and temperature overshoot that inevitably occur during temperature control are absorbed and buffered by the high heat capacity material of the heating bath, and their high-frequency components are strongly attenuated by the insulation layer. This prevents these control disturbances from being directly transmitted to the core sensitive components, fundamentally solving the problem of interference introduced by the temperature control action itself.

[0037] 3. This invention uses the insulation layer in the constant temperature control method and device as the first line of defense, combined with an internal multi-layer thermal buffer structure, which greatly extends the response time constant of the entire device to changes in external temperature. When a slow temperature change occurs in the external environment, the temperature change amplitude of the target temperature control zone is significantly compressed, and the change process is extremely gradual. This reduces the stringent requirements for the constant temperature conditions of the equipment's operating environment and enhances the applicability and reliability of the equipment in non-ideal environments.

[0038] 4. In this invention, the heating module and temperature sensor in the constant temperature control method and device are tightly coupled within the heating zone and in direct contact with the heating bath. Combined with optimized temperature control circuit parameters, this results in an extremely fast response speed for the entire temperature control module. This ensures that the temperature of the heating bath can be quickly and accurately adjusted to the set point. Simultaneously, the symmetrical layout of multiple heating modules and the excellent thermal conductivity of the copper / aluminum heating bath and storage bath guarantee a uniform distribution of heat within their respective cavities, avoiding uneven stress or temperature fields caused by internal thermal gradients.

[0039] 5. This invention employs a multi-layered nested structure for the constant temperature control method and device, resulting in clear logic and a well-defined thermal path. Preferred materials such as copper, aluminum, felt, and polyethylene foam are common, low-cost, and stable industrial materials. The heating module utilizes standard power transistors for heat dissipation, eliminating the need for special heating elements, thus reducing manufacturing costs and improving reliability. The temperature control circuit adopts a classic proportional-integral circuit control form, which is technically mature and easy to design and debug. Attached Figure Description

[0040] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0041] Figure 1 This is a schematic diagram of the structure of the constant temperature control device of the present invention.

[0042] Figure 2 This is a schematic diagram of the microscopic temperature curve structure of the temperature control target point of the present invention. Detailed Implementation

[0043] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.

[0044] Embodiments of the present invention provide a slow-fluctuation constant temperature control device, which includes a circuit part and a structural part, such as... Figure 1 As shown, the circuit part includes a temperature control module, and the structural part is a multi-layer nested structure, which can be spherical, cylindrical or square columnar. The structural part consists of insulation layer 1, heating zone 2, heating tank 3, heat insulation layer 4, heat storage tank 5 and target temperature control zone 6 from the outside to the inside.

[0045] The target temperature control zone 6 is the temperature control target point of this invention. The time required to achieve temperature stability in the target temperature control zone 6 can be 1 hour to 2 hours, or even longer. The slow fluctuation after the temperature in the target temperature control zone 6 has stabilized is the objective of this invention.

[0046] This constant temperature control device is suitable for situations where the target temperature in the target temperature control zone 6 is more than 10 degrees Celsius higher than the maximum operating ambient temperature.

[0047] The insulation layer 1 isolates the entire constant temperature control device from the external environment in terms of temperature. The size and shape of the insulation layer depend on the actual application conditions. The interior is preferably circular. The material of the insulation layer 1 can be nano aerogel felt or ordinary felt.

[0048] The temperature control module includes a temperature control circuit 9, several heating modules 7 and several temperature sensors 8. The heating modules 7 and temperature sensors 8 are evenly distributed in the heating zone 2.

[0049] The heating module 7 is connected to the heating tank 3 through direct contact so that heat can be transferred to the heating tank 3.

[0050] The heating bath 3 is made of a material with a high heat capacity ratio. For the same volume, it has a high structural heat capacity, and is less affected by environmental temperature changes. It also helps smooth out fluctuations in the temperature control module within a temperature control cycle. Copper and aluminum are particularly recommended materials for the heating bath 3, as both have high heat capacity ratios and good thermal conductivity, which aligns with the objectives of this invention.

[0051] The insulation layer 4 serves two purposes: first, it reduces the rate of heat transfer from the heating tank 3 to the storage tank 5, significantly reducing the temperature fluctuation in the storage tank 5 compared to the heating tank 3, by at least 10%; second, it provides insulation to the storage tank 5, isolating it from external temperature variations. The insulation layer 4 is preferably made of felt or polyethylene foam, both of which have very low thermal conductivity and are readily available at low cost, ensuring stability and reliability when operating at 80℃~100℃.

[0052] The function of the heat storage tank 5 is to store the heat conducted in from the outside and to provide temperature equalization for the target temperature zone 6, reducing the rate and amplitude of temperature fluctuations at the target point. Similar to the heating tank 3, the heat storage tank is preferably made of copper or aluminum.

[0053] The target temperature control zone 6 is used to house components that require constant temperature, such as the crystal resonator (or the entire crystal oscillator) of a crystal oscillator, the physical components of an atomic clock, etc. The space and shape depend on the specific requirements.

[0054] The heating module 7 uses low-frequency medium / small power transistors or field-effect transistors, utilizing their power dissipation and heat generation characteristics to allocate almost all power for heating in the application. Structurally, the heating part of the power transistor is tightly integrated with the structure to be heated, ensuring rapid heat transfer while reducing the die temperature pressure of the power transistor during operation.

[0055] The heating module 7 uses multiple power transistors to generate heat together, and the layout adopts a symmetrical structure to ensure the balance of temperature transfer in all directions and the uniform internal temperature.

[0056] Temperature sensor 8 is responsible for collecting the temperature of the heating bath 3 next to the heating module 7. It must also be tightly coupled to the heating module 7 and feed the collected temperature back to the temperature control circuit 9 for negative feedback control.

[0057] The temperature control circuit 9 adopts a classic proportional-integral circuit form to receive temperature information fed back by the temperature sensor 9. By comparing the received temperature information with the set threshold, it calculates and controls the heating module 7 to perform high-power heating, low-power heating, and stop heating.

[0058] The heating module 7 and temperature sensor 8 should be structurally installed to ensure rapid temperature transfer. In conjunction with the parameter settings of the temperature control circuit 9, the time constant of the transfer function of the entire temperature control module should be controlled within 5 seconds.

[0059] A slow-fluctuation constant temperature control method is applied to the aforementioned constant temperature control device. The constant temperature control method is as follows:

[0060] At the start of operation, the temperature control module begins to work. When the temperature information returned by the temperature sensor 8 is far below the set threshold, the temperature control circuit 9 controls the heating module 7 to start high-power heating. As the temperature rises, the temperature information returned by the temperature sensor 8 gradually approaches the set threshold, and the temperature control circuit 9 controls the heating module 7 to gradually reduce the heating power until equilibrium is reached.

[0061] When temperature control reaches equilibrium, microscopically, the temperature curve on temperature sensor 8 is a continuously fluctuating first sawtooth waveform, similar to... Figure 2 The A-curve has a period approximately 3 to 5 times the time constant of the entire temperature control module. A longer period indicates a larger fluctuation amplitude, and vice versa. This fluctuation is a normal phenomenon in the operation of the entire temperature control module.

[0062] Controlling and shortening the time constant means adjusting the attached time constant. Figure 2 The period of the A-curve is shortened, and the amplitude is reduced. The time intervals T1 and T2 in the figure originate from temperature overshoot and undershoot caused by the delay in temperature transmission, resulting in microscopic fluctuations in the actual controlled temperature. While the absolute value of these fluctuations is actually very small, they are considered relatively large for crystals requiring constant temperature. Therefore, one of the core achievements of this invention is to achieve, through the coordination of circuit parameters and structure, the attached... Figure 2 The temperature curve A in the design was initially adjusted to a second sawtooth waveform, namely the temperature curve B shown in the figure. The period of the second sawtooth waveform is relatively shorter than that of the first sawtooth waveform.

[0063] Heat continuously accumulates in heating tank 3, raising the temperature closer to the set temperature. Simultaneously, due to the high heat capacity ratio of the material in heating tank 3, it acts like a heat storage pool, accumulating heat and gradually reaching the set temperature. Meanwhile, in the attached... Figure 2 The amplitude of the temperature curve in section B will also decrease here, meaning the fluctuation will be reduced.

[0064] Heat is continuously conducted from the heating tank 3 inwards. Due to the low thermal conductivity of the insulation layer 4, this process takes a relatively long time. The heat conducted to the storage tank 5 causes its temperature to rise slowly. The material of the storage tank 5 is the same as that of the heating tank 3, and its temperature rise is a gradual process until it reaches the set temperature and enters a stable state. After reaching stability, the temperature fluctuation range of the storage tank 5 is greatly improved compared to that of the heating tank 3. Figure 2 The B curve decreases to the C curve (illustrated).

[0065] The above design of the present invention ensures that the rapid fluctuation factors in the target temperature control zone 6 are greatly reduced, and the fluctuation amplitude reaches a state of insensitivity, so that the target temperature control zone 6 of the device of the present invention only responds slowly to environmental fluctuations outside the insulation layer 1, and the goal of slow fluctuation is achieved.

[0066] Over a long period, under stable environmental conditions outside the insulation layer 1, the average value of this fluctuation curve is stable, meaning the temperature control module's temperature control is stable. When the external temperature environment changes but the change is small, the device of this invention will gradually smooth the change, ensuring the absolute value and slow fluctuation of the temperature in the target temperature control zone 6. When the external temperature environment changes slowly but significantly, such as the diurnal temperature range, the temperature of the heating tank 3 of this invention will fluctuate accordingly. Due to the presence of the insulation layer 1, the fluctuation range will be very small. The target temperature control zone 6 will also fluctuate accordingly, but the amplitude will be much lower than that of the heating tank 3. If actual needs also require such fluctuation, a dual-layer temperature control technology can be used to control the temperature range outside the insulation layer 1.

[0067] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A slow-fluctuation constant temperature control device, comprising a circuit part and a structural part, characterized in that, The circuit section includes a temperature control module; The structure is a multi-layered nested structure, consisting of, from the outside in, a heat insulation layer (1), a heating zone (2), a heating tank (3), a heat insulation layer (4), a heat storage tank (5), and a target temperature control zone (6); The target temperature control zone (6) is the target temperature control point; The insulation layer (1) isolates the entire constant temperature control device from the external environment in terms of temperature. The heating module (7) is connected to the heating tank (3) by direct contact; The heating tank (3) is made of a material with a high heat capacity ratio; The heat insulation layer (4) is used to reduce the rate of heat transfer from the heating tank (3) to the heat storage tank (5), and at the same time, it is used to keep the heat storage tank (5) warm. The heat storage tank (5) is used to store the heat conducted in from the outside and to provide temperature balance for the target temperature zone (6); The target temperature control zone (6) is used to house components that require constant temperature.

2. The slow-fluctuation constant temperature control device according to claim 1, characterized in that, The temperature control module includes a temperature control circuit (9), several heating modules (7) and several temperature sensors (8); The heating module (7) and temperature sensor (8) are both evenly distributed within the heating zone (2).

3. The slow-fluctuation constant temperature control device according to claim 2, characterized in that, The heating module (7) uses a low-frequency, medium / low-power power transistor, which is either a transistor or a field-effect transistor. The heating module (7) tightly integrates the heating part of the power transistor with the structure to be heated.

4. The slow-fluctuation constant temperature control device according to claim 3, characterized in that, The heating module (7) is powered by multiple power transistors and has a symmetrical layout.

5. The slow-fluctuation constant temperature control device according to claim 4, characterized in that, The temperature sensor (8) is responsible for collecting the temperature of the heating tank (3), and is tightly coupled with the heating module (7), and feeds back the collected temperature to the temperature control circuit (9) for negative feedback control.

6. The slow-fluctuation constant temperature control device according to claim 5, characterized in that, The temperature control circuit (9) adopts a proportional-integral circuit form to receive temperature information fed back by the temperature sensor (9). By comparing the received temperature information with the set threshold, it controls the high-power heating, low-power heating and stopping heating of the heating module (7).

7. The slow-fluctuation constant temperature control device according to claim 6, characterized in that, The interior of the insulation layer (1) is circular.

8. The slow-fluctuation constant temperature control device according to claim 7, characterized in that, The heating tank (3) is made of copper or aluminum, and the material of the storage tank (5) is the same as that of the heating tank (3).

9. A slow-fluctuation constant temperature control device according to claim 8, characterized in that, The insulation layer (4) is made of felt or polyethylene foam.

10. A slow-fluctuation constant temperature control method, applied to the constant temperature control device of claim 9, characterized in that, The constant temperature control method is as follows: At the start of operation, the temperature control module starts working. When the temperature information returned by the temperature sensor (8) is much lower than the set threshold, the temperature control circuit (9) controls the heating module (7) to start high-power heating. As the temperature rises, the temperature information returned by the temperature sensor (8) gradually approaches the set threshold. The temperature control circuit (9) controls the heating module (7) to gradually reduce the heating power until equilibrium is reached. At this time, the temperature curve on the temperature sensor (8) is the first sawtooth waveform. By controlling and shortening the time constant, the first sawtooth waveform curve is initially designed and adjusted into a second sawtooth waveform, the period of which is relatively shorter than that of the first sawtooth waveform; Heat accumulates in the heating tank (3) and the temperature rises towards the set temperature, gradually reaching the set temperature. At the same time, the amplitude of the second sawtooth waveform decreases. The heat on the heating tank (3) is continuously conducted into the interior, and the temperature of the storage tank (5) rises slowly until it reaches the set temperature and enters a stable state. After reaching stability, the temperature fluctuation of the storage tank (5) decreases.

Images