A range hood

Abstract

The utility model relates to technical fields discloses a kind of range hood, range hood includes machine body, air duct, centrifugal fan being located in air duct;Centrifugal fan includes volute, impeller being located in volute;The profile of volute, from volute tongue along the direction of impeller rotation, including diffuser part, the profile of diffuser part at least includes at least one reference helix segment and one outer expansion section;Outer expansion section is non-helix line section, in polar coordinate system with the rotation center of impeller as origin, in the polar angle range determined by the starting point and end point of outer expansion section, the radial dimension of outer expansion section is greater than the radial dimension on the virtual line formed by reference helix segment extension, with same polar angle position.This application's range hood, by setting outer expansion section in the diffuser part of volute of centrifugal fan, make that the radial dimension of volute internal flow passage in specific area increase, form the channel of local expansion, can effectively slow down the airflow speed in this area, reduce the flow resistance in volute interior, improve energy conversion efficiency, improve the maximum air volume of entire fan even range hood complete machine.

Description

Technical Field

[0001] This utility model relates to the technical field, and in particular to a range hood. Background Technology

[0002] Range hoods are an indispensable appliance in modern kitchens. Their core component, the centrifugal fan, generates negative pressure through a high-speed rotating impeller, drawing in cooking fumes and expelling them outdoors, thus purifying the kitchen air.

[0003] Centrifugal fans typically consist of an impeller driven by a motor and a volute casing surrounding the impeller. During operation, the impeller rotates at high speed, drawing in the oily fumes collected by the fume hood from its center and then ejecting them at high speed along the tangent of the blades using centrifugal force. The volute casing's main function is to collect this high-speed airflow exiting from the impeller's outer edge and, through its specially designed diffuser channel with a gradually increasing cross-sectional area along the airflow direction, smoothly and efficiently convert the airflow's kinetic energy into static pressure energy. This overcomes the resistance of subsequent exhaust ducts, ultimately allowing the oily fumes to be smoothly discharged outdoors.

[0004] In existing technologies, to achieve the aforementioned energy conversion, the volute profile design of centrifugal fans typically follows a continuous, smooth expansion pattern, most commonly employing a single helix, such as a logarithmic helix or an Archimedean helix. This traditional profile design can achieve good aerodynamic performance under certain conditions.

[0005] However, as modern kitchens increasingly demand slimmer and more compact range hood designs, the volute and the entire fan system within it must be installed inside a size-constrained frame (body). This inherent space limitation presents a significant challenge to traditional volute design. Specifically, once the frame dimensions (especially the width) of the range hood are determined, the overall size and expansion rate of the traditional volute are also strictly constrained.

[0006] Under these circumstances, the only way to further increase the maximum airflow of a range hood is usually to increase the impeller speed. However, high-speed airflow is prone to boundary layer separation within the confined volute channel, generating turbulence and causing a sharp increase in internal flow resistance. This significant internal resistance not only results in low energy conversion efficiency for the fan, making the increase in airflow negligible, but also significantly increases the aerodynamic noise generated by the turbulence, severely impacting the overall performance of the product.

[0007] Therefore, how to overcome the performance bottleneck of traditional volute design, effectively reduce internal flow resistance, and improve energy conversion efficiency under the strict constraints on the overall size of range hoods, so as to achieve maximum air volume without significantly increasing noise, has become a technical problem that urgently needs to be solved in this field.

[0008] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Utility Model Content

[0009] In response to the problems mentioned in the background art, this application provides a range hood that, by setting an outward expansion section in the diffuser section of the centrifugal fan, increases the radial dimension of the flow channel inside the volute in a local area, forming a locally expanded channel, which can effectively slow down the airflow speed in the area, reduce the flow resistance inside the volute, improve energy conversion efficiency, and increase the maximum air volume of the entire fan and even the entire range hood.

[0010] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0011] In some embodiments of this application, a range hood is provided, comprising:

[0012] The lower part of the body has a smoke collection hood;

[0013] An air duct is located inside the machine body, and its inlet is connected to the smoke collection hood;

[0014] A centrifugal fan, located inside the duct, is used to draw oil fumes from the duct inlet and discharge them from the machine body.

[0015] The centrifugal fan includes a volute and an impeller disposed inside the volute;

[0016] The profile of the volute extends from the volute tongue along the impeller rotation direction and includes a diffuser section. The profile of the diffuser section includes at least a reference helical segment and an outward expansion segment.

[0017] The extended section is a non-helical line segment. In the polar coordinate system with the rotation center of the impeller as the origin, within the polar angle range determined by the start and end points of the extended section, the radial dimension of the extended section is greater than the radial dimension of the virtual line formed by the extension of the reference helical line segment, which has the same polar angle position.

[0018] In some embodiments of this application, the outwardly expanding segment is an eccentric circular arc segment. The geometric features of the eccentric circular arc segment are clear, easy to draw accurately, and in subsequent mold manufacturing and product injection molding, it is also easy to ensure its processing accuracy and surface quality.

[0019] In some embodiments of this application, the profile of the diffuser is further provided with a transition arc segment at each end of the outward expansion section, for smoothly connecting the outward expansion section with the adjacent line segment. The function of the transition arc segment is to smoothly and tangentially connect the outward expansion section with the adjacent reference spiral line segment, so that the airflow can transition smoothly.

[0020] In some embodiments of this application, the profile of the volute further includes a first straight segment and a volute tongue arc segment that are sequentially arranged and smoothly connected before the diffuser, and the volute tongue arc segment is connected to the front end of the diffuser.

[0021] The profile of the volute is connected to a second straight segment after the diffuser section, which forms the outlet of the volute. In this way, a complete profile structure of the volute is formed.

[0022] In some embodiments of this application, the profile of the volute includes a first straight line segment AB, a volute tongue arc segment BC, a first spiral segment CD, a first transition arc segment DE, an eccentric arc segment EF as the outward expansion segment, a second transition arc segment FG, a second spiral segment GI, and a second straight line segment IK, which are sequentially arranged and smoothly connected on the circumference.

[0023] Among them, the first helical segment CD and the second helical segment GI are reference helical segments that follow the same helical formula. The volute profile is formed by the above eight segments arranged sequentially on the circumference and smoothly connected to form a complete volute profile.

[0024] In some embodiments of this application, a rectangular coordinate system is established with the rotation center of the impeller as the coordinate origin O, the horizontal line passing through the coordinate origin as the X-axis, and the vertical line passing through the coordinate origin as the Y-axis; the eccentric circular arc segment EF passes through the Y-axis and is compared with the Y-axis at point Q, and intersects the virtual line at point P;

[0025] Among them, the distance from point Q to the origin O is greater than the distance from point P to the origin O.

[0026] By introducing a Cartesian coordinate system and using the above geometric relationships, it can be demonstrated again in a measurable way that the eccentric circular arc segment EF is outwardly expanded relative to the original reference helix. Furthermore, the eccentric circular arc segment EF is designed to pass through the Y-axis, which fully utilizes the relatively ample height space inside the frame, increasing the flow channel cross-sectional area at the bottom of the volute without increasing the critical installation width of the volute.

[0027] In some embodiments of this application, the distance between point Q and point P is H2, and the value of H2 ranges from 10 mm to 15 mm. Within this value range, flow resistance can be effectively reduced without causing excessive curvature of the outward expansion section.

[0028] In some embodiments of this application, the center of the eccentric circular arc segment EF is O1, and the vertical distance from O1 to the X-axis and Y-axis is b;

[0029] The radial distance from the outer edge of the impeller along the negative X-axis to the volute profile is T;

[0030] The distance b and the distance T satisfy the following relationship: b = (0.4 ~ 0.5) * T.

[0031] In some embodiments of this application, the reference spiral segment is a logarithmic spiral segment; the logarithmic spiral segment satisfies the polar coordinate formula r1=R×e ωθ1 Where R is the impeller radius, r1 is the polar diameter, θ1 is the polar angle, and ω is the correction constant;

[0032] The volute has a width S1 determined by the correction constant ω, S1 = Rπ + R2π; where Rπ is the polar radius calculated by the polar coordinate formula when the polar angle θ1 is 180°, and R2π is the polar radius calculated by the polar coordinate formula when the polar angle θ1 is 360°.

[0033] The range hood also includes a frame for assembling the volute, wherein the width W1 of the frame and the width S1 of the volute satisfy the relationship: W1 = S1 + C, where C is a preset assembly gap.

[0034] The correction constant ω in the polar coordinate formula is obtained by back-calculating the ω value using the known frame width W1, thereby transforming the complex curve design into a simple dimensional substitution calculation, which significantly simplifies the design process and enhances the operability of the solution.

[0035] In some embodiments of this application, the outlet of the volute forms an opening, and the ratio of the area of ​​the opening to the inlet area of ​​the exhaust pipe is between 0.95 and 1.05. By designing the areas of the two to be approximately equal, it is ensured that the flow cross-sectional area does not change drastically when the airflow enters the exhaust pipe from the outlet of the volute. This maximizes the smooth transition of the airflow, reduces local pressure loss caused by abrupt changes in the interface area, and avoids airflow loss.

[0036] Compared with the prior art, the advantages and positive effects of this utility model are:

[0037] In the above embodiments, the range hood, by setting an outward expansion section in the diffuser of the centrifugal fan, increases the radial dimension of the internal flow channel in a local area, forming a locally expanded channel. This effectively slows down the airflow velocity in that area and suppresses the boundary layer separation tendency of the airflow near the volute wall, thereby significantly reducing the flow resistance inside the volute. The reduction in flow resistance allows the fan to deliver more air with the same input power, optimizing energy conversion efficiency and ultimately achieving the beneficial effect of increasing the maximum airflow of the entire fan and even the entire range hood. Simultaneously, a more stable internal flow field also reduces aerodynamic noise caused by turbulence and eddies, achieving a balance between high airflow and low noise.

[0038] Other features and advantages of this utility model will become clearer after reading the detailed embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic diagram of a range hood structure according to some embodiments is shown;

[0041] Figure 2 A schematic diagram of the structure of a centrifugal fan in a range hood according to some embodiments is shown;

[0042] Figure 3 A side view of a centrifugal fan in a range hood according to some embodiments is shown;

[0043] Figure 4 A schematic diagram of the profile of a volute according to some embodiments is shown;

[0044] Figure 5 A schematic diagram of the specific structure of the volute profile according to some embodiments is shown;

[0045] Figure 6 An enlarged view of the volute tongue portion in the volute profile according to some embodiments is shown;

[0046] Figure 7 A schematic diagram of the connection between the centrifugal fan and the exhaust pipe in a range hood according to some embodiments is shown;

[0047] Figure 8 It shows Figure 7 The front view;

[0048] Figure 9 A schematic diagram of the structure of a connector in a range hood according to some embodiments is shown;

[0049] Figure 10 A design flowchart of the volute profile according to some embodiments is shown;

[0050] Explanation of reference numerals in the attached figures:

[0051] 100 - Body 100; 110 - Smoke hood;

[0052] 200 - Centrifugal fan; 210 - Volute; 220 - Impeller;

[0053] 300-rack;

[0054] 400-exhaust pipe;

[0055] 500-Connector. Detailed Implementation

[0056] 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. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application.

[0058] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0059] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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.

[0060] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0061] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0062] like Figures 1-10 As shown, some embodiments of this application provide a range hood that aims to solve the problem that, under the condition of a fixed frame size, the centrifugal fan of the range hood has a bottleneck in aerodynamic efficiency, resulting in large airflow resistance, low energy conversion efficiency, and difficulty in further increasing the air volume.

[0063] like Figure 1 As shown, the range hood includes a body 100, the lower part of which is usually designed as an open smoke collection hood 110 to cover the cooking area of ​​the stove so as to efficiently collect the rising fumes.

[0064] An air duct is installed inside the unit, which is a sealed channel for the flow of cooking fumes. The inlet of the air duct is connected to the cavity of the fume collection hood, allowing the cooking fumes collected by the hood to smoothly enter the air duct. The outlet of the air duct is connected to the outdoor exhaust pipe.

[0065] A centrifugal fan is installed inside the duct. The function of the centrifugal fan is to generate strong suction to draw the oil fumes in from the duct inlet and finally exhaust them out of the machine through the exhaust port on the machine body.

[0066] like Figure 2 As shown, the centrifugal fan 200 mainly consists of a volute 210 and an impeller 220 disposed inside the volute.

[0067] The impeller is driven by a motor to rotate at high speed. The blades on the impeller do work on the gas, increasing its speed and pressure. The volute collects the gas ejected at high speed from the outer edge of the impeller and, through a diffuser channel, smoothly and efficiently converts the gas's kinetic energy into static pressure energy to overcome the resistance of the subsequent air duct and exhaust pipe.

[0068] See Figure 4 The core technical solution of this application lies in the optimized design of the profile of the volute.

[0069] The profile of the volute starts from the volute tongue and extends along the direction of impeller rotation, mainly forming a diffuser section.

[0070] The diffuser section design in this application breaks through the limitations of the traditional single spiral line, and includes at least a reference spiral segment and an outer expansion segment. In this embodiment, the diffuser section includes two reference spiral segments, namely the CD segment and the GI segment; the outer expansion segment is the EF segment (red segment).

[0071] The reference spiral segment is the curved segment that constitutes the basic profile of the diffuser, and it follows the conventional spiral expansion law.

[0072] The outer extension segment is a non-helical line segment. In the polar coordinate system with the impeller's rotation center as the origin, within the polar angle range determined by the start and end points of the outer extension segment, the radial dimension of the outer extension segment is greater than the radial dimension of the virtual line formed by the extension of the reference helical line segment, which has the same polar angle position.

[0073] This can be understood as follows: if the complete, traditional spiral profile is regarded as a baseline path, then the design of this application involves a local expansion outward (away from the impeller center) at a certain segment of that path, forming this outward expansion segment.

[0074] This imaginary path, formed by extending from the baseline spiral segment and used for comparison, is the virtual line mentioned above, as shown by the dashed line segment in the figure.

[0075] By setting up such an outward expansion section, it is equivalent to actively increasing the cross-sectional area of ​​airflow in a specific region inside the volute.

[0076] The aforementioned range hood, by incorporating an outward expansion section in the diffuser of the centrifugal fan's volute, increases the radial dimension of the internal flow channel in a specific area, creating a locally expanded channel. This effectively slows down the airflow velocity in that area and suppresses boundary layer separation near the volute wall, significantly reducing flow resistance within the volute. This reduced flow resistance allows the fan to deliver more air with the same input power, optimizing energy conversion efficiency and ultimately increasing the maximum airflow of the entire fan and range hood. Simultaneously, the smoother internal flow field reduces aerodynamic noise caused by turbulence and eddies, achieving a balance between high airflow and low noise.

[0077] In some embodiments, the specific geometry of the outer extension segment is preferred. The outer extension segment can be specifically configured as an eccentric circular arc segment.

[0078] An eccentric arc segment refers to a segment whose center is not located at the impeller's rotation center, but rather offset at a specific position. By rationally designing the center position and radius of this arc, a smooth, convex curve that meets the requirements for outward expansion can be easily constructed.

[0079] Using an eccentric circular arc segment as the outer expansion segment results in clear geometric features, making it easy to draw accurately. Furthermore, it facilitates ensuring processing precision and surface quality during subsequent mold manufacturing and product injection molding.

[0080] In other embodiments, the outward expansion segment can also take the form of other non-spiral curves. For example, it can be an elliptical arc, a parabolic segment, or a smooth spline curve generated through multiple control points. These curves can also achieve the radial expansion function, providing a variety of design options.

[0081] In some embodiments, in order to ensure the smoothness of the overall profile of the volute, a transition arc segment, DE segment and FG segment (green line segment) are respectively provided at both ends of the outward expansion segment.

[0082] The two transition arc segments serve to smoothly connect the outward expansion segment with the adjacent reference spiral segment, enabling the airflow to smoothly transition when passing through different curve segments, further optimizing the internal flow field and minimizing energy loss.

[0083] In some embodiments, a complete profile structure of the volute is defined. Before the diffuser, i.e., near the starting region of the volute tongue, the volute profile also includes a first straight segment and a volute tongue arc segment, i.e., segments AB and BC, which are sequentially arranged and smoothly connected. The volute tongue arc segment is the true starting point of the diffusion process and connects to the front end of the diffuser.

[0084] Following the diffuser section, at the end of the volute, the profile is connected to a second straight section, namely the IK section. This second straight section forms the outlet of the volute, used to discharge the pressurized airflow and connect it to the subsequent air duct.

[0085] In some embodiments, a preferred and complete volute profile configuration is provided.

[0086] like Figure 5 As shown, the profile is formed by eight line segments arranged sequentially and smoothly connected on the circumference, namely: the first straight line segment AB, the volute tongue arc segment BC, the first spiral line segment CD, the first transition arc segment DE, the eccentric arc segment EF as the outer expansion segment, the second transition arc segment FG, the second spiral line segment GI, and the second straight line segment IK.

[0087] The first helical segment CD and the second helical segment GI together constitute the reference helical segment.

[0088] Furthermore, the first helical segment CD and the second helical segment GI follow the same helical formula. That is, both the first helical segment CD and the second helical segment GI are generated by the same helical equation.

[0089] This clarifies the concept of the invention, which is to cut off a middle section from an originally complete and continuous reference spiral line and replace it with the combined structure of "first transition arc segment DE + eccentric arc segment EF + second transition arc segment FG", thereby realizing the function of local expansion.

[0090] In some embodiments, a Cartesian coordinate system is introduced to more accurately describe the geometric features of the extension segment.

[0091] like Figure 5 As shown, with the center of rotation of the impeller as the origin O, the horizontal line passing through the origin is defined as the X-axis, and the vertical line passing through the origin is defined as the Y-axis, thus establishing a standard rectangular coordinate system.

[0092] In this rectangular coordinate system, the eccentric circular arc segment EF is designed to pass through the Y-axis and intersect the Y-axis at a point, denoted as Q.

[0093] At the same time, the virtual line formed by extending the reference spiral segment will also intersect the Y-axis at a point, denoted as P.

[0094] The distance from point Q to the origin O is greater than the distance from point P to the origin O.

[0095] The above geometric relationships confirm, in a measurable way, that the eccentric circular arc segment EF is outwardly expanded relative to the original reference spiral.

[0096] Furthermore, the eccentric arc segment EF is designed to pass through the Y-axis, causing the volute to expand outward in the vertical direction, i.e., along the height of the frame. This fully utilizes the relatively ample height space inside the frame, increasing the flow channel cross-sectional area at the bottom of the volute without increasing the critical installation width. Simultaneously, this allows the high-speed airflow at the bottom of the volute to be slowed and buffered, effectively suppressing turbulence and significantly reducing internal flow resistance.

[0097] In some embodiments, the outward distance between points Q and P is optimized and limited.

[0098] The distance between point Q and point P, i.e., H2 = |OQ| - |OP|, has a preferred value range of 10 mm to 15 mm.

[0099] This numerical range is not set arbitrarily, but is an optimized range obtained by the designers through a large number of flow field simulation calculations and experimental verifications.

[0100] If H2 is too small, the outward expansion effect will be insignificant, and its contribution to reducing flow resistance will be limited. If H2 is too large, although the flow channel space will be further increased, it may lead to excessive curvature of the outward expansion section, which may cause new airflow separation and make the overall size of the volute too large, affecting its installation in the machine body.

[0101] In some embodiments, key design parameters for achieving the above-mentioned optimal outward extension distance are further provided.

[0102] Let O1 be the center of the eccentric circular arc segment EF, and let r2 be the radius. Let b be the perpendicular distance from O1 to the X-axis and y-axis, respectively. The center O1 is located in the third quadrant.

[0103] Define another parameter T, which is the radial distance from the outer edge of the impeller along the negative X-axis to the volute profile. Parameter T can reflect the dimension of the volute in the width direction.

[0104] The distance b and the distance T satisfy the following proportional relationship: b = (0.4 ~ 0.5) * T.

[0105] In some embodiments, the reference helical segment is a logarithmic helical segment. When a logarithmic helix is ​​used as the volute profile, the angle of attack loss of the airflow is small, making it a helix with excellent hydrodynamic performance and the most widely used in fan design.

[0106] In other embodiments, the reference helical segment may also be an Archimedean spiral or other spirals capable of gradually expanding the cross-sectional area.

[0107] In some embodiments, the logarithmic spiral segment satisfies the polar coordinate formula r1=R×e ωθ1, where R is the radius of the impeller, which is the design reference; r1 is the polar diameter of a point on the helix, θ1 is the polar angle of that point; ω is the correction constant.

[0108] The magnitude of the correction constant ω directly determines the radial expansion rate of the volute, thus affecting the overall left-right width of the volute, denoted as S1.

[0109] The formula for calculating S1 is: S1=Rπ+R2π.

[0110] Where Rπ is the theoretical polar radius calculated by the polar coordinate formula when the polar angle θ1 is 180° (i.e., π radians).

[0111] Similarly, R2π refers to the theoretical polar radius value calculated when the polar angle θ1 is 360° (i.e., 2π radians).

[0112] Furthermore, such as Figure 7 As shown, the range hood also includes a frame 300 for mounting and fixing the volute housing. The internal width W1 of the frame 300 is greater than the width S1 of the volute housing to allow for assembly clearance.

[0113] The two satisfy the relationship: W1 = S1 + C, where C is a preset assembly gap.

[0114] The preferred range for the assembly gap C is 4mm to 5mm. This range ensures ease of assembly while providing sufficient structural stability and support.

[0115] This embodiment provides a highly practical method for determining the correction constant ω in polar coordinate formulas. This method calculates the ω value using the known rack width W1, thereby transforming complex curve design into simple dimensional substitution calculations, significantly simplifying the design process and enhancing the operability of the solution.

[0116] In some embodiments, see Figure 9 The connection between the volute outlet and the flue pipe 400 was optimized.

[0117] The outlet of the volute forms an opening with a defined area. The ratio between the area of ​​this opening and the inlet cross-sectional area of ​​the exhaust pipe 400 installed in the user's home is between 0.95 and 1.05, meaning that the area of ​​the volute outlet is approximately equal to the inlet cross-sectional area of ​​the exhaust pipe 400.

[0118] The area of ​​both is designed to be approximately equal to ensure that the cross-sectional area of ​​the airflow does not change drastically when the airflow enters the exhaust pipe from the volute outlet.

[0119] If the areas of the two are too different (for example, the volute outlet is much larger or smaller than the flue inlet), strong turbulence and eddies will form at the interface, causing local pressure loss and noise.

[0120] By controlling the area ratio within a small range, the smooth transition of airflow can be ensured to the greatest extent, the local pressure loss caused by sudden changes in interface area can be reduced, and the loss of air volume can be avoided.

[0121] The mainstream 400 exhaust pipes on the market typically have a diameter φ of 180mm or 190mm.

[0122] Therefore, its inlet cross-sectional area S can be expressed by the formula S = πφ 2 / 4 is calculated.

[0123] The outlet of the volute is typically a rectangular opening. The length L of this rectangular opening is the distance between endpoint A of the first straight line segment AB and endpoint K of the second straight line segment IK. The length of the rectangular opening is equal to the thickness W of the volute.

[0124] Therefore, the outlet area of ​​the volute can be calculated using L*W.

[0125] In other embodiments, such as Figure 6 , Figure 7 and Figure 9 As shown, a connector 500 can be provided to connect the rectangular outlet of the volute and the circular inlet of the exhaust pipe. One end of the connector 500 has a rectangular opening that matches the outlet of the volute, and the other end has a circular opening that matches the standard exhaust pipe.

[0126] In some embodiments, other key geometric parameters of the volute profile are further optimized and limited to achieve optimal aerodynamic performance and overall assembly compatibility.

[0127] In the established rectangular coordinate system, such as Figure 4 As shown, the angle α formed by the first straight line segment AB and the X-axis preferably falls within the range of 50°≤α≤70°. This angle α defines the initial state of the airflow entering the volute tongue region. Within this range, it ensures that the airflow smoothly enters the volute tongue region, effectively avoiding flow separation and vortices caused by improper inlet angles.

[0128] If α is too small (<50°), the airflow will impact the volute tongue too gently, resulting in poor acceleration and early vortices; if it is too large (>70°), the airflow will generate vortex separation on the back of the volute tongue, which will also increase noise and reduce efficiency.

[0129] Meanwhile, the preferred range for the angle β formed by the second straight segment IK and the X-axis is 70°≤β≤85°. This angle β determines the direction in which the pressurized airflow exits from the volute. A reasonable β angle design is crucial for the efficient and low-resistance entry of the airflow into the subsequent air duct, achieving a smooth connection with the overall air duct system.

[0130] If β is too small (<70°), the airflow outlet direction does not match the subsequent air duct, resulting in turning losses, increased resistance, and reduced airflow; if β is too large (>85°), the airflow guidance effect is poor, the kinetic energy conversion is insufficient, and the outlet loss increases.

[0131] like Figure 5 As shown, the circumferential arc segment BC is the worm tongue part, and its profile is related to the worm tongue radius r and the gap t between the worm tongue and the outer edge of the impeller.

[0132] To achieve better noise reduction, the range of the volute tongue radius r must satisfy 8mm≤r≤12mm.

[0133] If r is too small (<8mm), the volute tongue will be very sharp, producing high-frequency whistling noise; if r is too large (>12mm), although it can make the airflow smoother and reduce noise, it will also reduce the effective volume of the volute, increasing internal airflow interference and reducing performance.

[0134] Meanwhile, the clearance t is directly related to the impeller diameter D, and its value range is 0.04D≤t≤0.06D.

[0135] If the gap t is too small (<0.04D), the blades and the volute tongue are prone to interference, resulting in extremely high noise and a risk of collision; if the gap t is too large (>0.06D), it will cause severe airflow backflow, large leakage losses, and a significant decrease in efficiency and wind pressure.

[0136] Regarding the impeller diameter D, the design starting point for the centrifugal fan casing is to determine the impeller diameter D based on the working air pressure p and rotational speed n of the smoke fan.

[0137] Where ρ is the air density. These are coefficients related to the impeller structure.

[0138] The impeller width b is usually proportional to the diameter D, and is generally taken as b = (0.4~0.6) * D.

[0139] like Figure 3 As shown, the thickness W of the volute must be sufficient to completely accommodate the impeller and provide enough space for airflow. Therefore, the volute thickness W is related to the impeller width b and must satisfy the relationship W = Δ * b, where Δ is a constant, typically ranging from 1.1 to 1.3.

[0140] To ensure that the volute can be installed smoothly in the frame of the range hood, the distance H1 from the top of the volute to the center of the impeller must be within the range of 170mm≤H1≤190mm.

[0141] like Figure 10 As shown, the design method of the volute profile in this application is as follows:

[0142] 1. Establish a coordinate system: With the center of rotation of the impeller as the origin O, establish a rectangular coordinate system.

[0143] 2. Determine the impeller size: Calculate the impeller diameter D and impeller width b based on the known parameters such as the required air pressure and speed of the range hood.

[0144] 3. Determine the basic dimensions of the volute: Calculate the volute thickness W based on the determined impeller width b. Simultaneously, calculate the clearance t between the impeller and the volute based on the impeller diameter D.

[0145] 4. Based on the known parameters of the flue pipe diameter, calculate the inlet cross-sectional area S of the flue pipe, and based on S and the volute thickness W, calculate the outlet length L of the volute.

[0146] 5. Draw the reference helical segment: Based on the frame length W1 and the assembly clearance C, determine the volute width S1, calculate the correction coefficient ω based on S1, and draw the reference helical segment CI that constitutes the main part of the volute diffuser.

[0147] 6. Draw the starting and ending line segments of the volute: Based on the determined volute tongue radius r, the distance H1 from the volute outlet to the impeller center, the clearance t, the included angle α, and the included angle β, draw the first straight line segment AB, the volute tongue arc segment BC, and the second straight line segment IK.

[0148] 7. Draw the outer expansion segment and transition segment: Select an appropriate H2 to determine the intersection point Q of the eccentric circular arc segment EF and the Y-axis; calculate the coordinates of the center O1 of the eccentric circular arc segment EF based on the dimensional parameter T of the volute in the width direction; draw the eccentric circular arc segment EF as the outer expansion segment with O1 as the center and O1Q as the radius; finally, draw two transition circular arc segments DE and FG, which are used to smoothly and tangentially connect the eccentric circular arc segment EF to the reference helix CI. The final volute profile is then drawn.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

[0150] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A range hood, comprising: The body has a smoke collection hood at its lower part; An air duct is located inside the machine body, and its inlet is connected to the smoke collection hood; A centrifugal fan, located inside the duct, is used to draw oil fumes from the duct inlet and discharge them from the machine body. The centrifugal fan includes a volute and an impeller disposed inside the volute; Its features are, The profile of the volute extends from the volute tongue along the impeller rotation direction and includes a diffuser section. The profile of the diffuser section includes at least a reference helical segment and an outward expansion segment. The extended segment is a non-spiral line segment. In a polar coordinate system with the rotation center of the impeller as the origin, within the polar angle range determined by the start and end points of the extended section, the radial dimension of the extended section is greater than the radial dimension of the virtual line formed by the extension of the reference helical segment, which has the same polar angle position.

2. The range hood according to claim 1, characterized in that, The extended section is an eccentric circular arc segment.

3. The range hood according to claim 2, characterized in that, The profile of the diffuser section also has a transition arc segment at each end of the outer expansion section.

4. The range hood according to claim 1, characterized in that, The profile of the volute, before the diffuser, also includes a first straight segment and a volute tongue arc segment that are sequentially arranged and smoothly connected, and the volute tongue arc segment is connected to the front end of the diffuser. The profile of the volute is connected to a second straight segment after the diffuser section, which forms the outlet of the volute.

5. The range hood according to claim 3, characterized in that, The profile of the volute includes a first straight line segment AB, a volute tongue arc segment BC, a first spiral segment CD, a first transition arc segment DE, an eccentric arc segment EF as the outward expansion segment, a second transition arc segment FG, a second spiral segment GI, and a second straight line segment IK, which are sequentially arranged and smoothly connected on the circumference. Wherein, the first spiral segment CD and the second spiral segment GI are reference spiral segments that follow the same spiral formula.

6. The range hood according to claim 2, characterized in that, With the volute's outlet facing upwards as a reference, and the impeller's rotation center as the origin O, a rectangular coordinate system is established with the horizontal line passing through the origin as the X-axis and the vertical line passing through the origin as the Y-axis. The eccentric arc segment EF passes through the Y-axis and is compared with the Y-axis at point Q, and intersects the virtual line at point P. Among them, the distance from point Q to the origin O is greater than the distance from point P to the origin O.

7. The range hood according to claim 6, characterized in that, The distance between point Q and point P is H2, and the value of H2 ranges from 10mm to 15mm.

8. The range hood according to claim 7, characterized in that, The center of the eccentric circular arc segment EF is O1, and the perpendicular distance from O1 to the X-axis and Y-axis is b. The radial distance from the outer edge of the impeller along the negative X-axis to the volute profile is T; The distance b and the distance T satisfy the following relationship: b = (0.4 ~ 0.5) * T.

9. The range hood according to claim 1, characterized in that, The reference spiral segment is a logarithmic spiral segment; the logarithmic spiral segment satisfies the polar coordinate formula r1=R×e ωθ1 Where R is the impeller radius, r1 is the polar diameter, θ1 is the polar angle, and ω is the correction constant; The volute has a width S1 determined by the correction constant ω, S1 = Rπ + R2π; where Rπ is the polar radius calculated by the polar coordinate formula when the polar angle θ1 is 180°, and R2π is the polar radius calculated by the polar coordinate formula when the polar angle θ1 is 360°. The range hood also includes a frame for assembling the volute, wherein the width W1 of the frame and the width S1 of the volute satisfy the relationship: W1 = S1 + C, where C is a preset assembly gap.

10. The range hood according to claim 1, characterized in that, The outlet of the volute forms an opening, and the ratio of the area of ​​the opening to the inlet area of ​​the exhaust pipe is between 0.95 and 1.05.

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