Liquid fuel preheating device

Abstract

This invention relates to the field of agricultural machinery, and more particularly to the technical field of burner fuel preheating devices for flame weeders, disclosing a liquid fuel preheating device. The device includes a double-layered hollow outer shell, with an annular cavity with an upper opening formed between the inner and outer layers. A winch within the cavity divides the cavity into an inner preheating chamber and an outer preheating chamber. A distribution ring is sealed at the top of the outer shell for supplying liquid fuel. The winch has protruding ribs to extend the path or time for fuel to flow to the bottom. An injection pipe is located at the bottom of the outer shell for fuel outflow. This device utilizes waste heat from the combustion chamber to preheat the fuel, significantly increasing the temperature and vaporization degree of the liquid fuel. It improves combustion efficiency and calorific value utilization without altering the combustion chamber structure, reducing fuel consumption and carbon buildup. It is particularly suitable for open, non-pressurized combustion chambers.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery, particularly to the field of flame weeding machine technology, and especially to the field of burner fuel preheating device technology for flame weeding machines, specifically to a liquid fuel preheating device. Background Technology

[0002] Flame weeding, as a physical weeding method, has advantages such as no pesticide residue, convenient operation, and high weeding efficiency, and is widely used in agricultural settings such as farmland and orchards. The core component of a flame weeding machine is the burner, and its combustion efficiency directly affects the weeding effect and fuel cost.

[0003] In existing technologies, most flame weed cutters use room-temperature liquid fuel directly injected into the combustion chamber for combustion, which has the following significant drawbacks: First, room-temperature liquid fuel has poor atomization and is difficult to mix fully with air, resulting in incomplete combustion. This not only significantly reduces the calorific value utilization rate and increases fuel consumption, but also easily produces a large amount of carbon deposits in the combustion chamber, which can clog nozzles and affect the service life of the burner with long-term use. Second, for open, non-pressurized combustion chamber structures, the combustion efficiency of room-temperature fuel is even lower, which cannot meet the actual needs of efficient and rapid weeding.

[0004] To address the aforementioned issues, some existing technologies have attempted to employ fuel preheating devices. However, these devices generally suffer from problems such as complex structures, unadjustable preheating effects, and poor sealing performance. Furthermore, excessive fuel preheating can lead to excessively high internal pressure, causing device leaks or structural deformation, making it difficult to promote and apply them on a large scale in flame weed killers. Summary of the Invention

[0005] Directly injecting room-temperature liquid fuel into the combustion chamber for combustion easily leads to carbon buildup and makes complete combustion difficult, especially in non-pressurized, open combustion chamber structures where combustion efficiency is low. However, increasing the fuel temperature and atomization can significantly improve combustion efficiency while reducing carbon buildup caused by incomplete combustion. To address the preheating problem of liquid fuel, this application provides a liquid fuel preheating device, particularly suitable for open, non-pressurized combustion chambers. By increasing the liquid fuel temperature and vaporization, combustion efficiency and calorific value utilization can be significantly improved without altering the combustion chamber structure, reducing fuel consumption and waste.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: This invention provides a liquid fuel preheating device, comprising an outer shell for heat exchange. The outer shell is defined as a double-layered hollow structure consisting of an inner layer and an outer layer, with the bottom of the inner and outer layers closed to form an annular cavity with an opening at the top. A auger is placed inside the annular cavity to divide it into an inner preheating cavity and an outer preheating cavity. A distribution ring for supplying liquid fuel into the annular cavity is sealed to the top of the outer shell. The auger is also fixedly provided with a protruding rib for extending the path or time of liquid fuel flow to the bottom of the outer shell. The bottom of the outer shell has an injection pipe for fuel outflow.

[0007] To further enhance the preheating effect of liquid fuel, the auger has an annular cage body with integrally formed spiral protrusions. These protrusions further physically separate the inner and outer preheating chambers, changing the fuel flow path from top-down to spiral-down, thus increasing the fuel flow path and allowing the fuel to flow for a longer time within both chambers, resulting in more thorough preheating.

[0008] To address and adapt to the varying heat exchange effects caused by materials with different thermal conductivity, resulting in different preheating times for the same liquid fuel to reach the same temperature, several design schemes for the protruding ribs are available. Specifically, different physical isolation effects are achieved by adjusting the gaps between the two sides of the ribs and the outer shell. The ribs protrude from the outer circumferential sidewall of the cage body, forming an external rib. An external gap is formed between the external rib and the outer sidewall of the outer shell, with a width L1 of 0.1-0.4 mm. A larger L1 results in more liquid fuel flowing directly downwards in the external preheating chamber, leading to less efficient heat exchange. Conversely, a smaller L1 results in less liquid fuel flowing through the external gap, with more flowing through the spiral channel formed by the external ribs, thus achieving more efficient heat exchange. By adjusting the specific value of the external gap width L1, the preheating effect of the liquid fuel can be adjusted to meet the preheating environment of different combustion chambers or burners. Similarly, the protruding ridge is formed on the inner circumferential sidewall of the cage body, creating an inner ridge. An inner gap is formed between the inner ridge and the inner sidewall of the outer shell, with a width L2 of 0.1-0.5 mm. Adjusting the width L2 of the inner gap affects the preheating effect of the liquid fuel in the inner preheating chamber, based on the same principle as adjusting the width L1 of the outer gap. It is worth noting that the inner preheating chamber is usually closer to the combustion chamber; therefore, the temperature and heat exchange efficiency of the inner preheating chamber are higher than those of the outer preheating chamber. Thus, in most cases, the width L2 > L1. However, for unconventional combustion chambers or burners using a central combustion structure, adjustments can be made according to the actual situation to achieve more balanced heating.

[0009] To further reduce the pressure difference between the inner and outer preheating chambers and avoid excessive fuel pressure due to overheating, preferably, a pressure-reducing groove is provided at the bottom of the cage body. This groove is defined as a spirally upward-extending notch positioned between two adjacent rings of the convex ridges. The pressure-reducing groove physically provides a connection between the inner and outer preheating chambers, allowing more fuel to mix earlier and preventing overheating. A larger lower notch results in lower gasification pressure, less fuel buildup, and less, if any, carbon deposits; conversely, a smaller lower notch results in higher gasification pressure, but carbon deposits tend to accumulate more easily in the inner layer of the cage body.

[0010] To further optimize fuel flow during preheating, this invention optimizes the originally static winch into a dynamically rotatable structure. Specifically, the winch includes an inner magnetic ring disposed at the top of the cage body. The inner magnetic ring has through holes spaced apart for introducing liquid fuel into the inner and outer preheating chambers, and blind holes for installing inner permanent magnets. An outer magnetic ring, magnetically coupled to the inner magnetic ring, is rotatably mounted on the outer outer wall of the outer shell. The outer magnetic ring is driven by a motor. The motor acts as a drive source, driving the outer magnetic ring to rotate. The outer magnetic ring, through magnetic coupling, drives the inner magnetic ring installed inside the outer shell to rotate. Since the protrusions on the winch are fixed, the length of the preheating flow path of the liquid fuel can be further extended or shortened by driving the winch to rotate in either forward or reverse direction, thereby achieving adjustment within a wider range.

[0011] To further optimize the coupling structure, preferably, the outer magnetic ring includes a toothed ring and a magnetic shielding component arranged coaxially, and a plurality of outer permanent magnets coupled and driven by the inner permanent magnet are mounted in a circumferential array on the magnetic shielding component.

[0012] Furthermore, the inner permanent magnet forms magnetic poles on its outer circumferential surface facing the magnetically conductive shield, and the magnetic poles are arranged alternately with N and S poles along the circumferential direction; the magnetically conductive shield is provided with a plurality of outer permanent magnets arranged circumferentially, and the outer permanent magnets form magnetic poles on their inner circumferential surface facing the inner magnetic ring, and the magnetic poles are arranged alternately with S and N poles along the circumferential direction; in the installed state, the N poles of the inner permanent magnets and the S poles of the outer permanent magnets are radially aligned one-to-one, and the S poles of the inner permanent magnets and the N poles of the outer permanent magnets are radially aligned one-to-one, and the number of magnetic pole pairs of the inner permanent magnets is equal to the number of magnetic pole pairs of the outer permanent magnets.

[0013] To reduce rotational resistance, sliding friction is replaced with rolling friction. This overcomes the space occupation of existing rotating connecting components like bearings and addresses issues such as bearing heat resistance and lubrication. Preferably, the magnetic shielding component also has threaded holes for mounting the ball bearing mechanism. The number of threaded holes, N≥3, is distributed in a circumferential array on the magnetic shielding component. The ball bearing mechanism can use existing high-temperature resistant stainless steel internal hexagonal balls. Through a spring plunger self-lubrication method, low-resistance rolling can be achieved while improving structural compactness. Arraying the ball bearing mechanism achieves the rotational effect of existing bearings while significantly simplifying the structure and facilitating flexible replacement later.

[0014] Preferably, to balance the preheating difference caused by the temperature difference between the outer and inner preheating chambers, the relative connection position between the through hole and the cage body can be adjusted according to the actual situation. Specifically, the bottom opening of the through hole is divided into an outer outlet and an inner outlet by the cage body. The outer outlet is defined as the channel connecting the through hole and the outer preheating chamber, and the inner outlet is defined as the channel connecting the through hole and the inner preheating chamber. If the temperature on the inner outlet side is higher, then a structure with the inner outlet larger than the outer outlet is adopted; conversely, if the temperature on the inner outlet side is lower, then a structure with the inner outlet smaller than the outer outlet is adopted. The preheating temperature difference between the outer and inner preheating chambers is minimized as much as possible by utilizing the distribution of fuel flow rate.

[0015] To provide greater fuel mixing and pressure equalization redundancy, preferably, the bottom of the housing is provided with an enlarged annular mixing chamber, and the injection pipe is configured to communicate tangentially with the mixing chamber. Beneficial effects

[0016] 1. The present invention adopts a double-layer hollow shell, which directly utilizes the waste heat of the combustion chamber for heat exchange, without the need for an additional heating source. The structure is simple and the energy loss is low. It can be adapted to a combustion chamber with good openness and no pressurization without modifying the original burner.

[0017] 2. The present invention uses a auger with spiral ridges to divide the annular cavity into two preheating chambers, changing the axial straight flow of fuel to spiral flow, which greatly extends the heat exchange time, allowing the fuel to be fully heated and gasified, fundamentally improving combustion efficiency and reducing carbon deposits.

[0018] 3. The present invention adopts a structure in which the protruding ridge and the side wall of the outer shell form a gap of controllable width. The degree of fuel preheating can be precisely adjusted by adjusting the gap width, while avoiding obstruction of fuel flow, preventing excessive internal pressure from causing device deformation or leakage, and ensuring safe and stable operation.

[0019] 4. The present invention adopts a pressure-reducing groove structure, which can quickly balance the pressure difference between the inner and outer preheating chambers, eliminate local high pressure and uneven gasification problems, and at the same time enable the fuel to be mixed and pressure-equalized in advance, thereby improving the stability and atomization effect of subsequent injection.

[0020] 5. The present invention adopts a magnetic coupling transmission structure composed of inner and outer magnetic rings, which eliminates the need to open transmission holes on the outer shell, completely solving the problem of dynamic sealing leakage in traditional mechanical transmission. At the same time, the fuel preheating effect can be dynamically adjusted within a wide range by controlling the speed and direction of the winch, adapting to different working conditions.

[0021] 6. This invention adopts a structure in which a ball bearing mechanism is arrayed on an outer magnetic ring, which transforms sliding friction into rolling friction, significantly reducing rotational resistance and energy loss. At the same time, it replaces traditional bearings, solving the problems of bearing heat resistance, lubrication difficulties, and large space occupation in high-temperature environments, making the device structure more compact and maintenance more convenient.

[0022] 7. The present invention adopts a flow-dividing structure that divides the bottom of the through hole into two outlets, inner and outer. The fuel flow can be distributed according to the temperature difference between the inner and outer preheating chambers to achieve balanced fuel preheating. This avoids excessive pressure caused by local overheating and makes full use of waste heat, further improving the heat utilization rate.

[0023] 8. The present invention adopts an expanded annular mixing chamber combined with a tangential injection pipe structure, which can fully mix and equalize the pressure of the preheated fuel, eliminate pressure fluctuations, and guide the fuel to form a swirling spray, significantly improving the atomization effect, making the fuel and air mix more fully, further improving combustion efficiency and calorific value utilization, and extending the service life of the burner. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a partial cross-sectional isometric view of the structure of this invention.

[0026] Figure 2 yes Figure 1 Another visual structural isometric view.

[0027] Figure 3 This is an axial sectional view of the present invention.

[0028] Figure 4 yes Figure 3 Enlarged view of the structure in area A.

[0029] Figure 5 yes Figure 3 Enlarged view of the structure in area B.

[0030] In the diagram: 1-Outer shell; 2-Outer magnetic ring; 21-Gear ring; 22-Magnetic shielding component; 23-Outer permanent magnet; 24-Threaded hole; 3-Windlock; 31-Cage body; 32-Outer convex ridge; 33-Inner magnetic ring; 331-Blind hole; 332-Through hole; 333-Outer outlet; 334-Inner outlet; 34-Outer preheating cavity; 35-Pressure reduction groove; 36-Outer gap; 37-Inner convex ridge; 38-Inner gap; 39-Inner preheating cavity; 4-Mixing cavity; 5-Distribution ring; 6-Supply pipe; 7-Injection pipe; 8-Injection head. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0036] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Example 1:

[0037] like Figures 1-4 As shown, this embodiment provides a liquid fuel preheating device, including an outer shell 1 for heat exchange. The outer shell 1 is defined as a double-layered hollow structure consisting of an inner layer and an outer layer, with the bottom closed between the inner and outer layers, forming an annular cavity with an open top. A winch 3 is placed inside the annular cavity to divide it into an inner preheating cavity 39 and an outer preheating cavity 34. A distribution ring 5 for supplying liquid fuel into the annular cavity is sealed to the top of the outer shell 1. A protruding rib is also fixedly provided on the winch 3 to prolong the path or time of liquid fuel flow to the bottom of the outer shell 1. The bottom of the outer shell 1 has an injection pipe 7 for fuel outflow.

[0038] Its structure and working principle are as follows: Liquid fuel enters the distribution ring 5 through the supply pipe 6, and the distribution ring 5 guides the fuel into the annular cavity at the top of the outer shell 1. Due to the presence of the auger 3, the annular cavity is divided into an inner preheating cavity 39 near the inner layer of the outer shell 1 and an outer preheating cavity 34 near the outer layer of the outer shell 1. The fuel flows downward under the action of gravity, but the protruding ribs fixed on the auger 3 block its direct falling path, forcing the fuel to spiral downward along the direction guided by the protruding ribs. During this process, the outer shell 1 absorbs heat from the combustion chamber and exchanges heat efficiently with the liquid fuel flowing through the inner preheating cavity 39 and the outer preheating cavity 34 through its double-wall structure. The fuel continuously absorbs heat in the long spiral path, its temperature rises, and it partially vaporizes. Finally, the preheated and partially vaporized fuel reaches the bottom of the outer shell 1, is sprayed out through the injection pipe 7, and is transported to the combustion chamber for combustion. This scheme effectively solves the problems of carbon buildup and incomplete combustion caused by the direct combustion of room temperature liquid fuel by extending the flow path and time of the fuel. Example 2:

[0039] like Figures 1-5As shown, this embodiment provides a preferred implementation based on Embodiment 1. In this embodiment, the auger 3 has an annular cage body 31, and the cage body 31 is integrally formed with a spiral-shaped protrusion. Specifically, the protrusion protrudes from the outer circumferential sidewall of the cage body 31 to form an outer protrusion 32, and an outer gap 36 is formed between the outer protrusion 32 and the outer sidewall of the outer shell 1. The width of the outer gap 36 is L1 = 0.1-0.4 mm. The protrusion protrudes from the inner circumferential sidewall of the cage body 31 to form an inner protrusion 37, and an inner gap 38 is formed between the inner protrusion 37 and the inner sidewall of the outer shell 1. The width of the inner gap 38 is L2 = 0.1-0.5 mm.

[0040] Its working principle and beneficial effects are as follows: The integrally formed spiral-shaped outer convex rib 32 and inner convex rib 37 further divide the inner preheating chamber 39 and the outer preheating chamber 34 into finer spiral channels. Liquid fuel must flow along these spiral channels, and most of the fuel cannot fall directly, thus maximizing the flow path and heat exchange time, and significantly improving the preheating effect. At the same time, the existence of the outer gap 36 and the inner gap 38 provides a "bypass" for some fuel, allowing a small amount of fuel to flow directly downwards. By precisely controlling the tiny widths of L1=0.1-0.4mm and L2=0.1-0.5mm, the proportion of fuel falling directly can be adjusted. Narrower gaps force more fuel to flow through the long spiral path, resulting in more thorough preheating; wider gaps allow more fuel to pass through quickly, preventing excessive fuel vaporization and excessive pressure in the chamber due to excessive preheating time, which could affect the injection speed of the injection pipe 7 or cause deformation of the outer shell 1. Typically, the inner preheating chamber 39, which is closer to the heat source, has a higher temperature. Therefore, L2 can be set to L1 to achieve balanced heating and pressure control of the inner and outer preheating chambers. Example 3:

[0041] like Figure 1 , Figure 3 As shown, this embodiment provides another preferred implementation based on embodiment 2. In this embodiment, a pressure-reducing groove 35 is provided at the bottom of the cage body 31. The pressure-reducing groove 35 is defined as a notch extending spirally upward, and the pressure-reducing groove 35 is disposed between two adjacent rings of the convex ridges.

[0042] Its working principle and beneficial effects are as follows: As the fuel spirals down through the inner preheating chamber 39 and the outer preheating chamber 34, the fuel temperature and vaporization degree in the two chambers may differ due to variations in distance from the heat source or differences in heat exchange efficiency, leading to pressure differences. The pressure-reducing groove 35 physically connects the inner and outer preheating chamber spaces between adjacent ring convex ridges. This allows some fuel to flow laterally between the two chambers through the pressure-reducing groove 35 before reaching the bottom mixing chamber 4, thereby balancing the pressure difference between the inner preheating chamber 39 and the outer preheating chamber 34 and preventing excessive pressure in a single chamber. Simultaneously, this pre-mixing also promotes temperature and composition homogenization, creating favorable conditions for the final mixing and stable injection of fuel at the bottom of the outer shell 1. Example 4:

[0043] like Figures 1-5 As shown, this embodiment provides a dynamically adjustable optimization scheme based on embodiment 2 or embodiment 3. In this embodiment, the winch 3 further includes an inner magnetic ring 33 disposed on the top of the cage body 31. The inner magnetic ring 33 has through holes 332 for introducing liquid fuel into the inner preheating chamber 39 and the outer preheating chamber 34 respectively, and blind holes 331 for installing the inner permanent magnet. An outer magnetic ring 2 magnetically coupled to the inner magnetic ring 33 is rotatably mounted on the outer outer wall of the outer shell 1. The outer magnetic ring 2 is driven by a motor. The outer magnetic ring 2 includes a toothed ring 21 and a magnetically conductive shield 22 arranged coaxially. Multiple outer permanent magnets 23 coupled to and driven by the inner permanent magnet are mounted in a circumferential array on the magnetically conductive shield 22. The magnetically conductive shield 22 is also provided with threaded holes 24 for installing a ball bearing mechanism. The number of threaded holes 24 N≥3 are distributed in a circumferential array on the magnetically conductive shield 22. In this embodiment, 45# steel is used as the material for the magnetic shielding component 22, which can effectively shield the magnetic induction lines, prevent the magnetic induction lines from diverging, further constrain the magnetic induction lines to form a magnetic shielding space, and improve the magnetic coupling effect. Of course, those skilled in the art can also use other magnetically conductive materials according to actual needs in order to achieve better technical results.

[0044] Its working principle and beneficial effects are as follows: The motor drives the outer magnetic ring 2 to rotate through the gear ring 21. The outer permanent magnet 23 on the outer magnetic ring 2 drives the inner magnetic ring 33 sealed inside the outer shell 1 and the entire auger 3 fixed thereto to rotate synchronously through magnetic coupling. By controlling the direction and speed of the motor, the auger 3 can be rotated forward or backward relative to the stationary outer shell 1. When the rotation direction of the auger 3 is opposite to the natural downward flow of the fuel spiral, it will further hinder the fuel flow and effectively lengthen the preheating path; conversely, when the rotation direction is the same as the fuel flow direction, it will accelerate the fuel passage and shorten the preheating path. This allows the preheating intensity to be precisely and dynamically adjusted within a wider range to adapt to the working requirements of different fuel types or ambient temperatures. In addition, the ball mechanism installed in the threaded hole 24, such as high-temperature resistant stainless steel internal hexagonal balls, directly contacts the mounting base of the outer magnetic ring 2, converting sliding friction into rolling friction, effectively reducing rotational resistance, solving the problem of limited lubrication and installation space of traditional bearings in such high-temperature environments, resulting in a more compact structure and easier maintenance and replacement. Example 5:

[0045] like Figures 3-5 As shown, this embodiment provides an optimized magnetic coupling structure based on embodiment 4. In this embodiment, the inner permanent magnet forms magnetic poles on its outer peripheral surface facing the magnetically conductive shield 22, and the magnetic poles are arranged alternately with N and S poles along the circumferential direction. The magnetically conductive shield 22 is provided with a plurality of outer permanent magnets 23 arranged circumferentially. The outer permanent magnets 23 form magnetic poles on their inner peripheral surface facing the inner magnetic ring 33, and the magnetic poles are arranged alternately with S and N poles along the circumferential direction. In the installed state, the N pole of the inner permanent magnet and the S pole of the outer permanent magnet 23 are radially aligned one-to-one, and the S pole of the inner permanent magnet and the N pole of the outer permanent magnet 23 are radially aligned one-to-one, and the number of magnetic pole pairs of the inner permanent magnet is equal to the number of magnetic pole pairs of the outer permanent magnet 23.

[0046] Its working principle and beneficial effects are as follows: the alternating circumferential arrangement of the inner and outer permanent magnets 23, with their radially aligned poles, constitutes a highly efficient radial magnetic coupling transmission system. When the magnetic shield 22 rotates under external force, a strong radial attraction is generated between the outer permanent magnet 23 (e.g., the S pole) and the inner permanent magnet (N pole) on the opposing auger 3, while a repulsive force is generated with the adjacent inner permanent magnet (S pole). The combined effect of the attraction and repulsion ensures the synchronicity and efficiency of the magnetic transmission, allowing the torque of the outer magnetic ring 2 to be transmitted to the inner magnetic ring 33 with almost no loss, driving the auger 3 to rotate precisely. The equal number of pole pairs ensures consistent angular velocity, avoids relative slippage, and achieves precise synchronous control. Example 6:

[0047] like Figures 3-5 As shown, this embodiment provides an optimized scheme combining flow splitting and pressure equalization. In this embodiment, the bottom opening of the through hole 332 is divided into an outer outlet 333 and an inner outlet 334 by the cage body 31. The outer outlet 333 is defined as a channel connecting the through hole 332 and the outer preheating chamber 34, and the inner outlet 334 is defined as a channel connecting the through hole 332 and the inner preheating chamber 39. An enlarged annular mixing chamber 4 is provided at the bottom of the outer shell 1, and the injection pipe 7 is configured to communicate tangentially with the mixing chamber 4.

[0048] Its structure and working principle are as follows: Liquid fuel from the distribution ring 5 first enters the through-hole 332 of the inner magnetic ring 33. The bottom of the through-hole 332 is separated by the cage body 31, causing the fuel to be divided into two paths: one path enters the outer preheating chamber 34 through the outer outlet 333, and the other path enters the inner preheating chamber 39 through the inner outlet 334. In actual operation, the cross-sectional area ratio of the outer outlet 333 and the inner outlet 334 can be designed according to the temperature difference between the inner preheating chamber 39 (closer to the heat source) and the outer preheating chamber 34 (farthest from the heat source). For example, when the temperature of the inner preheating chamber 39 is higher, the size of the inner outlet 334 can be designed to be smaller than that of the outer outlet 333 to reduce the amount of fuel entering the high-temperature region and prevent overheating; and vice versa. This achieves the initial distribution of fuel flow according to the difference in preheating environment, making the temperature of the inner and outer chambers more uniform after preheating. Subsequently, the two preheated fuel streams meet, mix, and further equalize in the expanded annular mixing chamber 4 at the bottom of the outer casing 1. Finally, they enter the injection pipe 7 tangentially along the mixing chamber 4, forming a swirling flow before being ejected by the injection head 8. This tangential entry helps to form a stable rotating airflow within the injection pipe 7, enhancing the mixing effect between the fuel and any residual steam, and ensuring a stable supply of high-quality gas-liquid mixed fuel to the combustion chamber. Example 7:

[0049] like Figures 1-5As shown, the liquid fuel preheating device provided in this embodiment includes an outer shell 1 for heat exchange. The outer shell 1 is defined as a double-layered hollow structure composed of an inner layer and an outer layer. The bottom of the inner layer and the outer layer are closed, forming an annular cavity with an open top. A auger 3 is placed in the annular cavity to divide the annular cavity into an inner preheating cavity 39 and an outer preheating cavity 34. The auger 3 has an annular cage body 31, and a spiral rib is integrally formed on the cage body 31. The rib protrudes from the outer circumferential sidewall of the cage body 31 to form an outer rib 32. An outer gap 36 is formed between the outer rib 32 and the outer sidewall of the outer shell 1, and the width of the outer gap 36 is L1=0.2mm. The rib protrudes from the inner circumferential sidewall of the cage body 31 to form an inner rib 37. An inner gap 38 is formed between the inner rib 37 and the inner sidewall of the outer shell 1, and the width of the inner gap 38 is L2=0.3mm. The bottom of the cage body 31 is provided with a pressure relief groove 35, which is defined as a notch extending spirally upward, and the pressure relief groove 35 is provided between two adjacent rings of convex ribs.

[0050] The winch 3 also includes an inner magnetic ring 33 disposed on the top of the cage body 31. The inner magnetic ring 33 has through holes 332 for introducing liquid fuel into the inner preheating chamber 39 and the outer preheating chamber 34 respectively, and blind holes 331 for installing the inner permanent magnet. The bottom opening of the through hole 332 is divided by the cage body 31 into an outer outlet 333 and an inner outlet 334. The outer outlet 333 is defined as the channel connecting the through hole 332 and the outer preheating chamber 34, and the inner outlet 334 is defined as the channel connecting the through hole 332 and the inner preheating chamber 39. An outer magnetic ring 2, magnetically coupled to the inner magnetic ring 33, is rotatably mounted on the outer outer wall of the outer shell 1. The outer magnetic ring 2 is driven by a motor. The outer magnetic ring 2 includes a toothed ring 21 and a magnetic shield 22 arranged coaxially. Multiple magnets 23 coupled to and driven by the inner permanent magnet are mounted in a circumferential array on the magnetic shield 22. The magnetic shield 22 is also provided with threaded holes 24 for mounting a ball bearing mechanism. The number of threaded holes 24 is N=6 and they are distributed in a circumferential array on the magnetic shield 22. The inner permanent magnet forms magnetic poles on the outer peripheral surface of its oriented magnetic shield 22, and the magnetic poles are arranged alternately with N and S poles along the circumferential direction; the magnet 23 forms magnetic poles on its inner peripheral surface facing the inner magnetic ring 33, and the magnetic poles are arranged alternately with S and N poles along the circumferential direction; in the installed state, the N pole of the inner permanent magnet and the S pole of the magnet 23 are radially aligned, the S pole of the inner permanent magnet and the N pole of the magnet 23 are radially aligned, and the number of magnetic pole pairs of the inner permanent magnet is equal to the number of magnetic pole pairs of the magnet 23.

[0051] The top of the outer shell 1 is sealed with a distribution ring 5 for supplying liquid fuel to the annular cavity, and the top of the distribution ring 5 is connected to a supply pipe 6; the bottom of the outer shell 1 is provided with an enlarged annular mixing chamber 4, and the bottom of the outer shell 1 has an injection pipe 7 for fuel to flow out. The injection pipe 7 is configured to communicate with the tangential direction of the mixing chamber 4, and an injection head 8 is installed at the end of the injection pipe 7.

[0052] Working Principle: This device is installed on the upper part of the burner of the flame weed killer. The inner sidewall of the outer shell 1 is in direct contact with the combustion chamber. The high temperature generated by combustion is continuously transferred to the liquid fuel in the annular cavity through the inner and outer layers of the outer shell 1. The liquid fuel enters the distribution ring 5 through the supply pipe 6, and is evenly distributed by the distribution ring 5 to the various through holes 332 on the inner magnetic ring 33. Then, it flows into the outer preheating chamber 34 and the inner preheating chamber 39 through the outer outlet 333 and the inner outlet 334, respectively. In this embodiment, the cross-sectional area of ​​the inner outlet 334 is larger than that of the outer outlet 333, allowing more fuel to flow into the higher-temperature inner preheating chamber 39, making full use of the waste heat of the combustion chamber and achieving balanced preheating of the fuel.

[0053] Liquid fuel entering the outer preheating chamber 34 flows downward along the spiral channel formed by the outer convex rib 32, while liquid fuel entering the inner preheating chamber 39 flows downward along the spiral channel formed by the inner convex rib 37. The spiral channels significantly extend the fuel flow path, allowing for sufficient heat exchange between the fuel and the high-temperature outer shell 1, resulting in a gradual increase in temperature and partial vaporization. The outer gap 36 and inner gap 38 allow a small amount of fuel to flow directly along the axial direction, avoiding the obstruction of fuel flow caused by the complete closure of the spiral channels. At the same time, by precisely controlling the width of the outer gap 36 and inner gap 38, the flow rate and preheating degree of the fuel are balanced, preventing excessive preheating and resulting in excessively high internal pressure. When the fuel flows to the bottom of the cage body 31, the fuel in the inner preheating chamber 39 and the outer preheating chamber 34 is pre-mixed through the pressure reducing groove 35, quickly balancing the pressure difference between the two and eliminating local high pressure and uneven vaporization problems.

[0054] When dynamic adjustment of the preheating effect is required, the motor is started. The motor drives the outer magnetic ring 2 to rotate around the outer shell 1 through gear meshing with the gear ring 21. The magnet 23 on the magnetic shield 22 and the inner permanent magnet in the blind hole 331 of the inner magnetic ring 33 are magnetically coupled, driving the inner magnetic ring 33 and the entire winch 3 to rotate synchronously. The ball bearing mechanism installed in the threaded hole 24 on the magnetic shield 22 makes rolling contact with the outer wall of the outer shell 1, converting sliding friction into rolling friction, greatly reducing rotational resistance. At the same time, it eliminates the need for traditional bearings, solving the problems of bearing heat resistance, lubrication, and space occupation. When the winch 3 rotates in the forward direction, the rotation direction of the outer protrusion 32 and the inner protrusion 37 is opposite to the direction of fuel gravity flow, further slowing down the fuel flow speed, prolonging the heat exchange time, and improving the preheating degree. When the winch 3 rotates in the reverse direction, the rotation direction of the outer protrusion 32 and the inner protrusion 37 is the same as the direction of fuel gravity flow, accelerating the fuel flow speed, shortening the heat exchange time, and reducing the preheating degree. By controlling the motor's speed and direction, the preheating effect of the fuel can be precisely adjusted over a very wide range to meet the combustion requirements under different operating conditions.

[0055] The preheated and initially mixed fuel flows into the annular mixing chamber 4 at the bottom of the outer casing 1, where it is further thoroughly mixed and pressurized to eliminate pressure fluctuations. Since the injection pipe 7 is tangentially connected to the mixing chamber 4, the fuel forms a swirling flow along the inner wall of the mixing chamber 4 under pressure. After passing through the injection pipe 7, it is atomized and ejected by the injection head 8, entering the combustion chamber for combustion. The swirling fuel atomization effect is better, allowing for more thorough mixing with air, significantly improving combustion efficiency and calorific value utilization, greatly reducing carbon deposit formation, and extending the burner's service life.

[0056] This embodiment integrates all the core technical features of the present invention. By utilizing the waste heat of the combustion chamber through a double-layer hollow structure, extending the preheating path with spiral convex ribs, controlling the degree of preheating through gap adjustment, balancing the pressure difference with a pressure-reducing groove, achieving dynamic adjustment through magnetic coupling transmission, achieving balanced preheating through a flow-dividing structure, and improving atomization effect through swirling mixing, a complete, efficient, and safe liquid fuel preheating system is formed. It is particularly suitable for the combustion chamber of a non-pressurized flame weed cutter with good openness. It can improve combustion efficiency and reduce fuel consumption without changing the original combustion chamber structure, while completely solving the problems of poor sealing, unstable pressure, and narrow adjustment range of traditional preheating devices.

[0057] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A liquid fuel preheating device, characterized in that: Includes an outer shell (1) for heat exchange, the outer shell (1) is defined as a double-layer hollow structure consisting of an inner layer and an outer layer, the bottom of the inner layer and the outer layer are closed to form an annular cavity with an opening at the top, a auger (3) for dividing the annular cavity into an inner preheating cavity (39) and an outer preheating cavity (34) is placed in the annular cavity, the top of the outer shell (1) is sealed with a distribution ring (5) for supplying liquid fuel to the annular cavity, the auger (3) is also fixedly provided with a protrusion for extending the path or time of liquid fuel flow to the bottom of the outer shell (1), and the bottom of the outer shell (1) has an injection pipe (7) for fuel to flow out.

2. The liquid fuel preheating device according to claim 1, characterized in that: The winch (3) has a ring-shaped cage body (31), and the cage body (31) is integrally formed with a spiral-shaped protrusion.

3. The liquid fuel preheating device according to claim 2, characterized in that: The protruding ridge is provided on the outer circumferential side wall of the cage body (31) to form an outer protruding ridge (32), and an outer gap (36) is formed between the outer protruding ridge (32) and the outer side wall of the outer shell (1), and the width of the outer gap (36) is L1=0.1-0.4mm; the protruding ridge is provided on the inner circumferential side wall of the cage body (31) to form an inner protruding ridge (37), and an inner gap (38) is formed between the inner protruding ridge (37) and the inner side wall of the outer shell (1), and the width of the inner gap (38) is L2=0.1-0.5mm.

4. A liquid fuel preheating device according to claim 2, characterized in that: The bottom of the cage body (31) is provided with a pressure-reducing groove (35), which is defined as a notch extending spirally upward, and the pressure-reducing groove (35) is provided between two adjacent rings of the convex ridges.

5. A liquid fuel preheating device according to claim 2, characterized in that: The winch (3) also includes an inner magnetic ring (33) disposed on the top of the cage body (31). The inner magnetic ring (33) has through holes (332) for introducing liquid fuel into the inner preheating chamber (39) and the outer preheating chamber (34) respectively, and blind holes (331) for installing the inner permanent magnet. An outer magnetic ring (2) magnetically coupled to the inner magnetic ring (33) is rotatably mounted on the outer outer wall of the outer shell (1). The outer magnetic ring (2) is connected to the motor drive.

6. A liquid fuel preheating device according to claim 5, characterized in that: The outer magnetic ring (2) includes a toothed ring (21) and a magnetic shield (22) arranged coaxially. Multiple outer permanent magnets (23) coupled and driven by the inner permanent magnet are mounted in a circumferential array on the magnetic shield (22).

7. A liquid fuel preheating device according to claim 6, characterized in that: The magnetic shield (22) is also provided with threaded holes (24) for installing ball bearing mechanism. The number of threaded holes (24) is N≥3 and they are distributed in a circumferential array on the magnetic shield (22).

8. A liquid fuel preheating device according to claim 5, characterized in that: The bottom opening of the through hole (332) is divided into an outer outlet (333) and an inner outlet (334) by the cage body (31). The outer outlet (333) is defined as the channel through which the through hole (332) communicates with the outer preheating cavity (34), and the inner outlet (334) is defined as the channel through which the through hole (332) communicates with the inner preheating cavity (39).

9. A liquid fuel preheating device according to any one of claims 1-8, characterized in that: The bottom of the outer shell (1) is provided with an enlarged annular mixing chamber (4), and the injection pipe (7) is connected to the tangential direction of the mixing chamber (4).

10. A liquid fuel preheating device according to claim 6, characterized in that: The inner permanent magnet forms magnetic poles on its outer circumferential surface facing the magnetic shield (22), and the magnetic poles are arranged alternately with N and S poles along the circumferential direction; the magnetic shield (22) is provided with a plurality of outer permanent magnets (23) arranged along the circumferential direction, the outer permanent magnets (23) form magnetic poles on their inner circumferential surface facing the inner magnetic ring (33), and the magnetic poles are arranged alternately with S and N poles along the circumferential direction; in the installed state, the N pole of the inner permanent magnet and the S pole of the outer permanent magnet (23) are radially aligned, the S pole of the inner permanent magnet and the N pole of the outer permanent magnet (23) are radially aligned, and the number of magnetic pole pairs of the inner permanent magnet is equal to the number of magnetic pole pairs of the outer permanent magnet (23).

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