HVAC air outlet air filtering and purifying structure

Abstract

The utility model discloses a kind of heating ventilation air conditioner air outlet air filtration purification structures, belong to heating ventilation air conditioning technical field.The utility model adopts technical scheme for a kind of heating ventilation air conditioner air outlet air filtration purification structure, including the air duct shell in air conditioner air outlet, the air duct shell middle part is rotatably connected with purification assembly, the purification assembly has four circumferential equidistant settings, mutually intercommunicating channel mouth, every described channel mouth is detachably connected with filter assembly;The utility model is through the design of rotatably connected purification assembly and detachable filter assembly, realizes multi-channel filtration switching, avoids the efficiency drop caused by single filter screen blockage, simultaneously simplifies maintenance process by modular structure, with the advantages of improving filtration efficiency, reducing energy consumption and convenient maintenance.

Description

Technical Field

[0001] This utility model belongs to the field of heating, ventilation and air conditioning technology, and specifically relates to an air filtration and purification structure for heating, ventilation and air conditioning vents. Background Technology

[0002] In modern building environments, HVAC systems, as core equipment for regulating indoor temperature and humidity and improving air quality, directly impact the health and comfort of the indoor environment through their air filtration and purification functions at the vents. As people's demands for indoor air quality continue to rise, the filtration structures of traditional HVAC vents are gradually revealing numerous shortcomings.

[0003] Currently, most HVAC vent filter devices on the market use a single, fixed filter design, requiring air to continuously pass through the same filter for purification. This structure has significant drawbacks: First, after long-term use, the filter is easily clogged by dust and particulate matter, leading to a substantial decrease in filtration efficiency. This not only affects the purification effect but also increases the operating resistance of the air conditioning system, resulting in energy waste. Second, replacing or cleaning the filter often requires shutting down the air conditioning system and disassembling the vent components, which is cumbersome and disrupts normal operation. In large public places or industrial environments, frequent downtime for maintenance can cause significant inconvenience and economic losses.

[0004] Furthermore, while some improved filter structures in existing technologies attempt to increase the number of filters, their unreasonable structural design prevents flexible switching and efficient utilization of the filters. These structures either cannot guarantee rapid filter replacement or fail to achieve smooth switching between different filters, resulting in low maintenance efficiency. Simultaneously, existing structures often lack effective drive mechanisms, hindering automatic rotation and switching of filter components and increasing the workload of manual operation.

[0005] More importantly, existing filtration structures generally suffer from difficulties in maintenance. When internal components need maintenance or parts such as bearings need to be replaced, the entire device often needs to be completely disassembled, which is not only time-consuming and labor-intensive but also prone to damaging components. This design flaw seriously affects the ease of maintenance and service life of the equipment. Utility Model Content

[0006] This utility model provides an air filtration and purification structure for HVAC vents to solve at least one of the above-mentioned technical problems.

[0007] The technical solution adopted in this utility model is as follows:

[0008] An air filtration and purification structure for a heating, ventilation, and air conditioning (HVAC) vent includes a duct housing located at the HVAC vent. A purification component is rotatably connected to the middle of the duct housing. The purification component has four circumferentially equidistant and interconnected channel openings, and a filter component can be detachably connected to each channel opening.

[0009] Furthermore, this application also proposes to include a drive unit for driving the purification component, the drive unit including a drive motor, the output end of the drive motor being fixedly connected to a shaft, the shaft being coaxially arranged and fixedly connected to the purification component.

[0010] Furthermore, this application also proposes that the purification component includes a rotating member, which is cylindrical or spherical, and the four channel openings are equally spaced along the circumference of the cylinder or sphere.

[0011] Furthermore, this application also proposes that the filter assembly includes a filter screen, which is fixed to the channel opening by screws and nuts.

[0012] Furthermore, this application also proposes that the air duct housing includes an air inlet, a middle housing, and an air outlet, wherein the inner cavity of the middle housing matches the shape of the rotating component so that the rotating component can rotate within the inner cavity of the middle housing.

[0013] Furthermore, this application also proposes that maintenance windows are provided on both sides of the central housing, and a sealing cover is detachably connected to the maintenance window.

[0014] Furthermore, this application also proposes that an inspection cover be detachably connected to the upper end of the middle housing.

[0015] Furthermore, this application also proposes that bearings are provided between the two ends of the rotating component and the central housing.

[0016] Due to the adoption of the above technical solution, the beneficial effects achieved by this utility model are as follows:

[0017] 1. This solution utilizes periodic switching between different filter units to ensure even load distribution across all filter components, extending their overall lifespan. This application enables the alternating use and maintenance of filter components during air conditioning system operation, preventing system downtime due to maintenance work. The rotary switching mechanism allows for rapid activation of a backup unit when a single filter component becomes clogged, maintaining stable air purification efficiency. The detachable connection structure simplifies the filter component replacement process and reduces the difficulty of routine maintenance.

[0018] 2. This solution ensures that at least one filter component is in effective working condition through a rotational switching mechanism, preventing increased system resistance due to clogging of a single filter component. This application enables online switching and maintenance of filter components, solving the problem of system operation interruption caused by downtime maintenance in traditional structures. The drive unit ensures smooth rotation of the purification components through coaxial transmission, avoiding component wear or noise caused by eccentric vibration, while simplifying the positioning operation of the filter components and improving maintenance efficiency.

[0019] 3. This solution utilizes a rotatable cylindrical or spherical structure, allowing four filter components to take turns performing filtration tasks. When one filter component becomes clogged, it can be switched to a backup filter component without system shutdown, overcoming the drawback of traditional structures that require system interruption for maintenance. This application enables online switching and maintenance of filter components, avoiding operational interruptions caused by air conditioning system shutdowns. The circumferentially equidistant channel openings result in a more uniform airflow pressure distribution, reducing the problem of excessive local resistance. The structural design of the cylindrical or spherical rotating components can adapt to duct housings with different spatial shapes, improving the equipment's applicability.

[0020] 4. This solution achieves a detachable connection using screws and nuts, ensuring installation stability while preventing damage to the duct structure during maintenance. This application allows for quick disassembly and assembly when the filter is clogged, without shutting down the air conditioning system or disassembling the air vent components, significantly shortening maintenance time and reducing labor costs. It is particularly suitable for high-dust environments requiring frequent filter replacements.

[0021] 5. This solution matches the inner cavity of the central housing with the shape of the rotating component, enabling stable rotation of the rotating component within the housing. Simultaneously, it retains the inspection window structure, allowing maintenance to be performed without complete disassembly of the housing. This application solves the problem of low maintenance efficiency caused by the cumbersome disassembly of traditional filter structures. The matching housing cavity and rotating component structure enable rapid switching of filter components, while the segmented housing design reduces the complexity of maintenance operations and minimizes system downtime. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of a specific embodiment of the present utility model;

[0023] Figure 2 This is a three-dimensional cross-sectional structural diagram of a specific embodiment of the present utility model;

[0024] Figure 3 This is a schematic diagram of the structure of the filter component in a specific embodiment of this utility model.

[0025] The accompanying drawings, which are provided to further illustrate the present invention and constitute a part of the present invention, illustrate exemplary embodiments of the present invention and are used to explain the present invention, but do not constitute an undue limitation of the present invention.

[0026] In the attached diagram:

[0027] 1. Duct housing; 11. Air inlet; 12. Middle housing; 121. Inspection cover; 122. Sealing cover; 13. Exhaust outlet; 2. Rotating component; 21. Channel opening; 22. Drive motor; 23. Bearing; 3. Filter screen. Detailed Implementation

[0028] To more clearly illustrate the overall concept of this utility model, a detailed description will be provided below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0030] Furthermore, it should be understood in the description of this utility model that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0031] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "implementation," "example," "aspect," or "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] Reference Figures 1 to 3 A HVAC air vent air filtration and purification structure includes a duct housing 1 located at the air vent, a filter screen 3, and a purification component rotatably connected to the middle of the duct housing 1. The filter screen 3 purification component has four circumferentially equidistant and interconnected channel openings 21, and each filter screen 3 channel opening 21 can be detachably connected to a filter component.

[0034] The duct housing 1 refers to the supporting structure that forms the airflow path. Specifically, it can be made of welded metal sheets to form a sealed channel that runs through the air conditioning vent, guiding airflow through the purification component. The purification component refers to a rotating device with multiple channels. Specifically, it can be a cylindrical or spherical metal cavity, which is rotatably connected to the duct housing 1 via bearings 23 to achieve the switching of different filter channel positions.

[0035] Specifically, when the air conditioning system is running, airflow enters the duct housing 1 from the air inlet 11 and flows through the currently aligned channel port 21 of the purification component and its connected filter component. When maintenance is required, the purification component is rotated to align the spare channel port 21 with the duct. At this time, the filter component of the original channel port 21 can be disassembled and cleaned without interrupting the air conditioning operation. The design of the four channel ports 21 being evenly distributed circumferentially allows switching to the adjacent filter unit with each quarter-circle rotation.

[0036] This solution utilizes periodic switching between different filter units to evenly distribute the load across all filter components, extending their overall lifespan. This application enables the alternating use and maintenance of filter components during air conditioning system operation, preventing system downtime due to maintenance work. The rotary switching mechanism allows for rapid activation of a backup unit when a single filter component becomes clogged, maintaining stable air purification efficiency. The detachable connection structure simplifies the filter component replacement process and reduces the difficulty of routine maintenance.

[0037] As a preferred example of the above embodiment, it also includes a drive unit for driving the purification component of filter screen 3. The drive unit of filter screen 3 includes a drive motor 22. The output end of the drive motor 22 of filter screen 3 is fixedly connected to a shaft. The shaft of filter screen 3 is coaxially arranged and fixedly connected to the purification component.

[0038] The drive motor 22 is a device used to provide rotational power, and can be implemented using an AC motor or a DC motor, transmitting torque to the shaft through its output end. The shaft refers to the transmission component connecting the drive motor 22 and the purification assembly, and can be implemented using a cylindrical rod made of metal or high-strength composite material, used to transmit the rotational motion of the motor to the purification assembly. Coaxial alignment means that the central axis of the shaft coincides with the rotation axis of the purification assembly, which can be achieved through precision machining or assembly processes to ensure uniform force distribution and reduce vibration during transmission.

[0039] After the drive motor 22 starts, it drives the shaft to rotate. The shaft is fixedly connected to the purification component and rotates coaxially, causing the entire purification component to rotate around its axis. The four circumferentially arranged channels 21 of the purification component switch to different working positions as it rotates, and the air is purified by passing through the filter components of different channels 21 in sequence. When a filter component needs maintenance, the drive motor 22 controls the purification component to rotate to a preset angle, moving the filter component to be maintained to the maintenance window position, allowing for disassembly and replacement without interrupting the operation of the air conditioning system.

[0040] Traditional fixed filter screens require system shutdown for disassembly and maintenance. This solution, however, utilizes a drive unit to automatically rotate and switch the purification components, separating the filter maintenance process from system operation. In existing technologies, filter screen 3 cannot be switched to a backup filter unit promptly after clogging. This solution ensures at least one filter component is in effective working condition through a rotational switching mechanism, preventing increased system resistance due to clogging of a single filter component. This application achieves online switching and maintenance of filter components, solving the system operation interruption problem caused by maintenance shutdowns in traditional structures. The drive unit uses coaxial transmission to ensure smooth rotation of the purification components, avoiding component wear or noise caused by eccentric vibration, while also simplifying the positioning operation of the filter components and improving maintenance efficiency.

[0041] As one specific implementation method of the purification component, refer to Figures 1-3 The filter screen 3 purification assembly includes a rotating component 2, which is cylindrical or spherical. Four filter screen 3 channel openings 21 are evenly spaced along the circumference of the cylinder or sphere. The rotating component 2 is a rigid structural component that can rotate around an axis. It can be made of metal or high-strength plastic material and has a through airflow channel inside. Its cylindrical or spherical shape can be adapted to the shape of the inner cavity of the air duct housing 1 to facilitate rotational movement.

[0042] A cylindrical or spherical rotating component 2 is supported within the duct housing 1 by bearings 23 at both ends. Four channel openings 21 are evenly arranged at 90-degree intervals along the circumference. When a filter element requires maintenance, the drive motor 22 rotates the rotating component 2, switching the adjacent channel opening 21 to the working position, allowing the filter element corresponding to the original channel opening 21 to be disassembled and replaced. The cylindrical structure reduces rotational inertia, while the spherical structure facilitates multi-angle airflow distribution; both shapes enable rapid switching of filter elements.

[0043] This solution utilizes a rotatable cylindrical or spherical structure to allow four filter components to take turns performing filtration tasks. When one filter component becomes clogged, it can be switched to a backup filter component without stopping the system, overcoming the drawback of traditional structures that require system interruption for maintenance. This application enables online switching and maintenance of filter components, avoiding interruptions caused by air conditioning system shutdowns. The circumferentially equidistant channel openings 21 result in a more uniform airflow pressure distribution, reducing the problem of excessive local resistance. The structural design of the cylindrical or spherical rotating component 2 can adapt to different spatial shapes of the duct housing 1, improving the equipment's applicability.

[0044] As one specific implementation of the filtering component, refer to Figure 2 and Figure 3 The filter assembly includes a filter screen 3, which is fixed to the channel opening 21 by screws and nuts. The filter screen 3 is a mesh structure woven from metal wire or plastic fiber, specifically stainless steel wire mesh or polyester fiber mesh, used to intercept dust, particulate matter, and other pollutants in the air. The screws and nuts are mechanical connectors consisting of a screw and a nut, specifically hexagonal head bolts with flat washers and spring washers. Tightening the nut generates axial pressure, rigidly fixing the filter screen 3 to the channel opening 21.

[0045] When filter screen 3 needs to be installed, the operator aligns it with the installation position of the channel opening 21, ensuring that the fixing holes on the edge of filter screen 3 are aligned with the pre-drilled threaded holes in the channel opening 21. Then, the screws are passed through the fixing holes and screwed into the threaded holes, and finally, the nut is used to tighten the screws. When filter screen 3 needs to be replaced or cleaned, simply loosen the nut in the reverse direction and remove the screws to remove the entire filter screen 3. This structure allows for quick installation and removal of filter screen 3 without compromising the airtightness of the duct.

[0046] This solution achieves a detachable connection using screws and nuts, ensuring installation stability while preventing damage to the duct structure during maintenance. This application allows for quick disassembly and assembly when the filter 3 is clogged, without shutting down the air conditioning system or disassembling the air vent components, significantly shortening maintenance time and reducing labor costs. It is particularly suitable for high-dust environments requiring frequent filter 3 replacements.

[0047] As a preferred embodiment of the air duct housing 1, refer to Figure 1 and Figure 2 The filter screen 3 and the air duct housing 1 include an air inlet 11, a middle housing 12 and an air outlet 13. The inner cavity of the middle housing 12 of the filter screen 3 matches the shape of the rotating part 2 so that the rotating part 2 can rotate in the inner cavity of the middle housing 12.

[0048] The duct housing 1 refers to the main structure that constitutes the airflow channel. It can be implemented using a segmented design, for example, by connecting the air inlet 11, the middle housing 12, and the exhaust outlet 13 into a single unit via flanges, facilitating installation and maintenance. The inner cavity of the middle housing 12 is the hollow structure that houses the rotating component 2. Its shape is adapted to the shape of the rotating component 2. For example, when the rotating component 2 is cylindrical, the inner cavity can be designed as a cylindrical cavity to ensure a uniform gap between the rotating component 2 and the housing during rotation. Matching the shape of the rotating component 2 means that the geometry of the outer surface of the rotating component 2 and the inner wall of the middle housing 12 are complementary, such as using a spherical or cylindrical fit, so that the rotating component 2 only needs to overcome minimal friction to achieve rotational movement within the housing.

[0049] The middle housing 12 serves as a transition section connecting the air inlet 11 and the air outlet 13, and its internal cavity shape is customized according to the shape of the rotating component 2. For example, when the rotating component 2 is cylindrical, the internal cavity of the middle housing 12 can be set as a cylindrical structure with a diameter slightly larger than that of the rotating component 2. The two ends of the rotating component 2 are supported by bearings 23, allowing it to rotate around its axis under the impetus of airflow or motor drive. The four circumferentially distributed channel openings 21 of the rotating component 2 align sequentially with the direction of the air inlet 11 as it rotates, allowing different filter components to take turns performing the filtration task. When maintenance is required, the rotating component 2 can be cleaned or replaced directly by opening the inspection windows on both sides of the middle housing 12.

[0050] This solution matches the inner cavity of the central housing 12 with the outer shape of the rotating component 2, enabling the rotating component 2 to rotate stably within the housing. Simultaneously, it retains the inspection window structure, allowing maintenance to be performed without complete disassembly of the housing. This application solves the problem of low maintenance efficiency caused by the cumbersome disassembly of housings in traditional filter structures. The matching housing inner cavity and rotating component 2 structure enable rapid switching of filter components, while the segmented housing design reduces the complexity of maintenance operations and minimizes system downtime.

[0051] As a preferred embodiment of the central shell 12, refer to Figure 1 The filter screen 3 has maintenance windows on both sides of the central housing 12, and a detachable sealing cover 122 is attached to each maintenance window. The maintenance window is an opening on both sides of the central housing 12 for maintenance of the internal filter components or rotating parts 2. It can be a rectangular or circular through-hole, and a flange structure can be provided at the edge of the opening to enhance the connection strength. The sealing cover 122 is a plate-like component covering the outside of the maintenance window, and can be fixed with screws or a snap-fit ​​connection. A sealing strip can be provided at its edge to maintain the airtightness of the air duct.

[0052] When cleaning or replacing the filter assembly is required, simply remove the sealing cover 122 to directly access the internal components through the access window, without disassembling the entire central housing 12. The sealing cover 122 fits snugly with the access window during installation to prevent air leakage. The access window can be positioned at an easily accessible height, such as a certain distance from the end of the housing, ensuring that maintenance tools can be easily inserted.

[0053] This solution, by incorporating a detachable inspection window structure, eliminates the need for complete disassembly of the air duct during maintenance, significantly reducing operation time and maintenance difficulty. This application enables rapid maintenance of the filter components without interrupting the air conditioning system, effectively minimizing equipment downtime while ensuring the air duct's sealing remains intact, avoiding structural wear caused by frequent disassembly.

[0054] Furthermore, a maintenance cover 121 is detachably connected to the upper end of the middle housing 12 of the filter screen 3. The maintenance cover 121 is located in the top area of ​​the middle housing 12 and is bolted to the mounting flange on the edge of the housing. When maintenance or replacement of the internal purification components is required, operators only need to remove the fixing bolts of the maintenance cover 121 to directly access the internal space of the housing without dismantling the entire air duct structure. A sealing strip can be installed between the maintenance cover 121 and the housing to maintain airtightness and prevent air leakage from affecting system operating efficiency. For example, the maintenance cover 121 can be designed as a split unit, and its coverage area can be adjusted according to the housing size to ensure that the operator's hands or tools can easily enter the interior for work.

[0055] This solution, through the design of the removable top access cover 121, ensures that the maintenance operation direction is aligned with the direction of gravity, preventing tools and parts from falling out and avoiding the risk of dust accumulation inside the equipment during maintenance. This application enables rapid inspection and maintenance of internal components without interrupting the air conditioning system, significantly reducing equipment downtime. The sealing structure of the access cover 121 effectively prevents external contaminants from entering the air duct, ensuring the cleanliness of the working environment for the purification components. Furthermore, the top access port optimizes the ergonomics of maintenance operations, reducing the labor intensity of operators.

[0056] As a preferred example of this application, see reference to Figures 1-3Bearings 23 are provided at both ends of the rotating component 2 of the filter screen 3 and between the rotating component 2 and the central housing 12. The rotating component 2 is rotatably connected to the central housing 12 through the bearings 23. When the drive unit drives the rotating component 2 to rotate, the bearings 23 can effectively distribute the radial load and reduce wear on the contact surface. For example, during the operation of the air conditioning system, the airflow pushes the particles attached to the surface of the filter assembly, causing uneven force on the rotating component 2. At this time, the bearings 23 can maintain the smooth rotation of the rotating component 2 and avoid jamming or abnormal noise due to excessive friction. Furthermore, the sealing design of the bearings 23 can prevent dust from entering the rotation gap and extend the service life of the components.

[0057] Compared to existing technologies, traditional filter structures typically use bushings or sliding fits for rotational support, which are prone to increased clearance or rotational resistance due to wear after long-term use. This solution, by introducing bearing 23, significantly reduces mechanical losses, ensuring smooth operation of the rotating component 2 even during frequent filter component switching, while also reducing the impact of heat generated by friction on the air conditioning system.

[0058] Through the above technical solution, this application can effectively reduce the frictional loss between the rotating part 2 and the housing, extend the maintenance cycle of the purification component, and improve the reliability of the filter component switching process, thereby reducing the need for downtime maintenance due to mechanical failure.

[0059] For any parts not mentioned in this utility model, existing technologies can be used or referenced.

[0060] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0061] The above description is merely an embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.

Claims

1. An air filtration and purification structure for a heating, ventilation, and air conditioning (HVAC) vent, comprising a duct housing (1) located at the HVAC vent, characterized in that, The air duct housing (1) is rotatably connected to a purification component. The purification component has four circumferentially equidistant and interconnected channel openings (21). Each channel opening (21) can be detachably connected to a filter component.

2. The air filtration and purification structure for HVAC vents according to claim 1, characterized in that, It also includes a drive unit for driving the purification component, the drive unit including a drive motor (22), the output end of the drive motor (22) is fixedly connected to a shaft, the shaft is coaxially arranged and fixedly connected to the purification component.

3. The air filtration and purification structure for HVAC vents according to claim 1, characterized in that, The purification component includes a rotating part (2), which is cylindrical or spherical, and the four channel openings (21) are equally spaced along the circumference of the cylinder or sphere.

4. The air filtration and purification structure for HVAC vents according to claim 3, characterized in that, The filter assembly includes a filter screen (3), which is fixed to the channel opening (21) by screws and nuts.

5. The air filtration and purification structure for HVAC vents according to claim 3, characterized in that, The air duct housing (1) includes an air inlet (11), a middle housing (12) and an air outlet (13). The inner cavity of the middle housing (12) matches the shape of the rotating part (2) so that the rotating part (2) can rotate in the inner cavity of the middle housing (12).

6. The air filtration and purification structure for HVAC vents according to claim 5, characterized in that, The middle housing (12) has inspection windows on both sides, and a sealing cover (122) is detachably connected to the inspection window.

7. The air filtration and purification structure for a heating, ventilation, and air conditioning vent according to claim 5, characterized in that, The upper end of the middle housing (12) is detachably connected to an inspection cover (121).

8. The air filtration and purification structure for a heating, ventilation, and air conditioning vent according to claim 7, characterized in that, The rotating part (2) is provided with bearings (23) between its two ends and the middle housing (12).

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