A precise temperature control structure for a liquid chromatograph column oven

Abstract

This invention belongs to the field of analytical instrument technology and discloses a precise temperature control structure for a liquid chromatograph column oven. It includes symmetrically arranged main and auxiliary ventilation units, a magnetic coupling transmission assembly, and a thermal compensation mechanism. The magnetic coupling transmission assembly enables an external drive source, synchronously driving the main and auxiliary ventilation units to rotate in opposite directions in a non-contact manner. This creates a stable and uniform cross-circulating airflow field inside the column oven. This design fundamentally eliminates the inherent wind speed attenuation and temperature stratification phenomena of a single fan. Simultaneously, the integrated thermal compensation mechanism effectively solves the problem of thermal expansion mismatch between components of different materials during temperature changes, ensuring the long-term operational stability of the system over a wide temperature range. This invention significantly improves the temperature uniformity and control accuracy of the column oven, while enhancing system reliability and avoiding potential contamination, thus possessing significant practical value.

Description

Technical Field

[0001] This utility model belongs to the field of analytical instrument temperature control technology, specifically relating to a high-precision temperature control structure for a high-performance liquid chromatograph (HPLC) column oven, designed to improve the uniformity of the internal temperature field. Background Technology

[0002] High performance liquid chromatography (HPLC) is a core technology in modern chemical and biological analysis. The accuracy and reproducibility of its analytical results largely depend on the precise and stable control of the column temperature. As a key component for achieving this control, the column oven's core task is to establish and maintain a uniform and constant temperature field throughout the chamber, especially around the column.

[0003] Currently, most mainstream column ovens on the market use air bath heating, which involves heating the air and using a fan to force convection to transfer heat. This type of design generally faces the following technical challenges: Traditional column ovens typically use a single fan to drive airflow. This layout inevitably creates a velocity gradient within the cavity, from the fan outlet to the far wall. Areas near the fan have high airflow velocity and good heat exchange efficiency, while areas far from the fan experience a significant decrease in airflow velocity, even forming low-speed vortex zones at structural corners. This uneven flow field directly leads to uneven temperature field, i.e., "temperature stratification" or "local hot / cold spots." The national standard GB / T26792-2020 "High Performance Liquid Chromatography" requires column oven temperature uniformity to be better than ±1.0℃. However, in traditional single-fan designs, the measured temperature difference often exceeds this range, directly affecting the stability of chromatographic retention time and the reliability of analytical results.

[0004] To simplify the structure, many designs place the fan drive motor directly inside the column oven cavity. This built-in design has several drawbacks: First, the motor itself is a heat source, and the heat generated by its operation can cause additional interference to the temperature control system; second, the mechanical wear of the motor bearings and transmission mechanism can generate particles, and its lubricant may also evaporate, posing a potential source of contamination for high-sensitivity analysis; finally, the vibration of the motor operation can be transmitted to the oven and the chromatographic column, which may affect column efficiency.

[0005] The operating temperature range of the column oven is relatively wide, generally from near room temperature to 80°C or higher. The drive shaft system that drives the fan is usually made of a variety of metal materials with different coefficients of thermal expansion. During the temperature cycle, the inconsistent dimensional changes of the components can lead to thermal stress concentration, which may cause shaft deformation, misalignment, or even jamming, thus affecting the long-term stability and service life of the system.

[0006] Therefore, a new technical solution is urgently needed to fundamentally solve the problems of uneven temperature field, low reliability of built-in drive source and thermal stress in existing wind-bath column temperature chambers. Utility Model Content

[0007] The purpose of this invention is to provide a precise temperature control structure for a liquid chromatograph column oven, which aims to overcome the problems in the prior art, such as uneven temperature field caused by unidirectional airflow, reliability and contamination risks caused by built-in drive components, and structural instability caused by thermal expansion and contraction.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A precise temperature control structure for a liquid chromatograph column oven includes: a main ventilation unit and an auxiliary ventilation unit, both of which are disposed within the column oven cavity and each includes a central rotating shaft and a blade assembly fixed to the rotating shaft; a magnetic coupling transmission assembly for synchronously driving the main ventilation unit and the auxiliary ventilation unit; and a thermal compensation mechanism connected between the magnetic coupling transmission assembly and the central rotating shaft.

[0009] In this structure, the main ventilation unit and the auxiliary ventilation unit are symmetrically arranged in the cavity, and their blade groups are driven to rotate in the opposite direction by the magnetic coupling transmission assembly, thereby forming a cross-circulating airflow in the cavity.

[0010] Furthermore, the thermal compensation mechanism is configured to compensate for differential thermal expansion between the magnetically coupled transmission assembly and the central rotating shaft caused by temperature changes.

[0011] Compared with the prior art, the present invention has the following advantages: 1. By employing a symmetrical layout of two ventilation units, a main one and an auxiliary one, and having their blades rotate in opposite directions, this invention creates a stable cross-circulating flow field inside the column oven. This flow field completely changes the unidirectional flow mode under single-fan drive, effectively eliminating wind speed gradients and low-speed vortex zones, making the airflow velocity and heat exchange efficiency at various points in the cavity more consistent, thereby significantly improving the uniformity of the temperature field and providing a guarantee for highly reproducible chromatographic analysis.

[0012] 2. The core magnetic coupling transmission component of this device enables the transmission of driving force through the wall, allowing the drive motor, which generates heat, vibration and potential pollution, to be completely placed outside the column temperature chamber. This non-contact transmission method avoids the wear and lubrication requirements of traditional mechanical couplings, eliminates vibration and pollution sources inside the chamber, and improves the long-term operational reliability of the system and the cleanliness of the analytical environment.

[0013] 3. The carefully designed thermal compensation mechanism of this device ingeniously solves the problem of thermal expansion mismatch between different material components when the temperature changes. It allows for a small, controlled relative displacement between components to release thermal stress, preventing structural deformation or decrease in accuracy caused by stress accumulation, and ensuring that the entire temperature control structure can operate stably and reliably in a wide operating range from low temperature to high temperature. Attached Figure Description

[0014] Figure 1 This is a three-dimensional schematic diagram of the overall structure of a precise temperature control structure for a liquid chromatograph column oven according to the present invention; Figure 2 This is a schematic diagram of the magnetic coupling transmission component in the precise temperature control structure of a liquid chromatograph column oven according to the present invention. Figure 3 This is a schematic diagram illustrating the principle of cross-airflow formation between the main and auxiliary ventilation units in the precise temperature control structure of a liquid chromatograph column oven according to this utility model. Figure 4 This is a partially enlarged schematic diagram of the thermal compensation mechanism in the precise temperature control structure of a liquid chromatograph column oven according to the present invention. Figure 5 This is a schematic diagram showing the installation position of the precise temperature control structure of the liquid chromatograph column oven inside the column oven according to the present invention.

[0015] In the diagram: 1-Main ventilation unit; 2-Auxiliary ventilation unit; 3-Magnetic coupling transmission assembly; 4-Thermal compensation mechanism; 5-Central rotating shaft; 6-Blade assembly; 7-Permanent magnet ring; 8-Hollow tubular body; 9-Wedge-shaped expansion groove; 10-Damping microcavity. Detailed Implementation

[0016] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 and Figure 5 As shown, the precise temperature control structure of this utility model is applied to the cavity of a liquid chromatography column oven. It mainly includes a symmetrically arranged main ventilation unit 1 and auxiliary ventilation unit 2, as well as a magnetic coupling transmission assembly 3 for driving them and a thermal compensation mechanism 4 for connection.

[0018] In a preferred embodiment, the main ventilation unit 1 and the auxiliary ventilation unit 2 are installed along the diagonal direction of the column temperature chamber to achieve optimal flow field symmetry. Each ventilation unit consists of a central rotating shaft 5 and a blade assembly 6 fixed thereon. The blade assembly 6 is preferably made of lightweight and high-strength composite material to reduce rotational inertia and is securely installed on the central rotating shaft 5 by means of mechanical interference fit to ensure that it does not loosen during high-speed rotation.

[0019] One of the core innovations of this utility model lies in the magnetic coupling transmission component 3, such as Figure 2 As shown, the component consists of a hollow tubular body 8 and permanent magnet rings 7 fixed at both ends. The component is mounted so that it can rotate around its axis and pass through the side wall of the column temperature chamber. The drive motor is located outside the chamber, and its output shaft is connected to an external magnet. The external magnet and the internal permanent magnet rings 7 form a magnetic coupling. When the external motor rotates, it drives the internal magnetic coupling transmission component 3 to rotate synchronously through non-contact magnetic field force. This design completely isolates the drive source from the heated chamber. To reduce the amount of heat transferred from the outside through the transmission component 3, the hollow tubular body 8 can be made of titanium alloy with low thermal conductivity or surface-treated aluminum alloy. To obtain efficient and stable torque transmission, the permanent magnet rings 7 can adopt a Halbach array design. This special magnetic pole arrangement can concentrate the magnetic field on one side, enhance the coupling force, and reduce external magnetic leakage.

[0020] like Figure 3 As shown, the blade group 6 of the main ventilation unit 1 and the blade group 6 of the auxiliary ventilation unit 2 are designed to rotate in opposite directions, for example, one clockwise and one counterclockwise. When they are driven synchronously, one unit pushes the air to one side and the other unit pushes the air to the other side. The two airflows converge, mix and circulate in the center of the cavity, forming a uniform cross flow field covering the entire cavity, thereby achieving uniform heat distribution.

[0021] Another core innovation of this utility model is the thermal compensation mechanism 4, the structure of which is as follows: Figure 4 As shown, the mechanism is located at the connection between the magnetic coupling transmission assembly 3 and the central rotating shaft 5 of each ventilation unit. It includes a wedge-shaped expansion groove 9 and a damping microcavity 10. The wedge-shaped expansion groove 9 is a tiny inclined structure machined on the connection interface, and its wedge angle of 1.5°±0.05° is precisely calculated. When temperature changes cause the transmission assembly 3 and the central rotating shaft 5, which are made of different materials, to produce different amounts of thermal expansion or contraction, the wedge-shaped groove allows a small amount of controllable axial relative sliding between the two, thereby effectively releasing the thermal stress that may cause the components to bend or be damaged.

[0022] Meanwhile, the damping microcavity 10 is located between the outer wall of the transmission component 3 and the corresponding hole wall of the housing. Its interior is filled with high-viscosity silicone oil as a damping medium. This high-viscosity silicone oil has good thermal stability. This design has a dual function: on the one hand, the viscous damping effect of the silicone oil can absorb the small vibrations generated during fan rotation and system operation, further improving the stability of the system; on the other hand, it also provides lubrication for the micro-sliding of the wedge-shaped expansion groove 9, ensuring a smooth and unobstructed stress release process.

[0023] In summary, this invention constructs a uniform temperature field from a fluid dynamics perspective through the symmetrical counter-rotation design of dual ventilation units; it structurally isolates heat sources, vibration sources, and contamination sources through external magnetic coupling transmission; and it solves the thermal stress problem under wide temperature range operation through a thermal compensation mechanism. The synergistic effect of these three elements comprehensively improves the performance of the liquid chromatography column oven.

[0024] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any way. Any simple modifications made by those skilled in the art using equivalent substitutions or transformations without departing from the concept described in the technical solution of this utility model shall still fall within the protection scope of the technical solution of this utility model.

Claims

1. A precise temperature control structure of a liquid chromatograph column oven, characterized in that, include: A main ventilation unit (1) and an auxiliary ventilation unit (2) are provided in the column temperature chamber, and each includes a central rotating shaft (5) and a blade assembly (6) fixed on the rotating shaft. A magnetic coupling drive assembly (3) is used to synchronously drive the main ventilation unit (1) and the auxiliary ventilation unit (2). A thermal compensation mechanism (4) is connected between the magnetic coupling transmission assembly (3) and the central rotating shaft (5); The main ventilation unit (1) and the auxiliary ventilation unit (2) are symmetrically arranged in the cavity, and their blade group (6) is driven to rotate in the opposite direction by the magnetic coupling transmission assembly (3), thereby forming a cross-circulating airflow in the cavity; Furthermore, the thermal compensation mechanism (4) is configured to compensate for the differential thermal expansion between the magnetic coupling transmission assembly (3) and the central rotating shaft (5) caused by temperature changes.

2. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 1, characterized in that: The main ventilation unit (1) and the auxiliary ventilation unit (2) are arranged along the diagonal direction of the column temperature chamber.

3. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 1, characterized in that: The magnetic coupling transmission assembly (3) is configured to achieve non-contact torque transmission through the side wall of the column temperature chamber, so that the drive motor can be installed outside the column temperature chamber cavity.

4. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 3, characterized in that: The magnetic coupling transmission assembly (3) includes a hollow tubular body (8), with a permanent magnet ring (7) fixedly connected to each end; the hollow tubular body (8) is made of titanium alloy or aluminum alloy with low thermal conductivity.

5. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 4, characterized in that: The permanent magnet ring (7) adopts a Halbach array magnetic pole distribution design to enhance coupling torque and reduce magnetic leakage.

6. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 1, characterized in that: The thermal compensation mechanism (4) includes a wedge-shaped expansion groove (9) disposed at the interface between the magnetic coupling transmission assembly (3) and the central rotating shaft (5). The wedge-shaped expansion groove (9) allows the two to generate a controlled micro-relative axial displacement during thermal expansion and contraction to release thermal stress.

7. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 6, characterized in that: The wedge angle of the wedge-shaped expansion groove (9) is set to 1.5°±0.05°.

8. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 6, characterized in that: The thermal compensation mechanism (4) also includes a damping microcavity (10), which is located between the outer wall of the magnetic coupling transmission assembly (3) and the inner wall of the column temperature chamber, and is filled with a high-viscosity damping medium.

9. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 8, characterized in that: The damping medium is high-viscosity silicone oil, which is used to absorb minor vibrations during system operation and to lubricate the relative displacement of the wedge-shaped expansion groove (9).

10. The precise temperature control structure of a column oven of a liquid chromatograph according to claim 1, characterized in that: The blade assembly (6) is made of lightweight, high-strength composite material and is mounted on the central rotating shaft (5) by mechanical interference fit.

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