Rail transit vehicle heat pump air conditioning system

Abstract

The utility model provides a kind of rail transit vehicle heat pump air conditioning system, including shell, shell includes indoor cavity, outdoor cavity, the indoor cavity and outdoor cavity are connected to form refrigerant circulation flow path by pipeline, still include fresh air cavity, the fresh air cavity includes respectively with first fresh air inlet, first fresh air outlet, waste exhaust air inlet and waste exhaust air outlet that communicate with total heat exchanger, fresh air and waste exhaust air carry out cross heat exchange in the total heat exchanger, the first fresh air outlet is communicated with first fresh air duct;Second fresh air opening is also set on the shell, the second fresh air opening is communicated with second fresh air duct, the first fresh air duct, second fresh air duct converge or respectively with the indoor cavity is communicated.The utility model provides a kind of rail vehicle heat pump air conditioning system, simple structure, low in cost, effectively realize the cold quantity / heat recovery of waste exhaust air in vehicle, improve the refrigeration effect of air conditioner.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning unit technology, and in particular to a heat pump air conditioning system for rail transit vehicles. Background Technology

[0002] During extreme weather events in summer or winter, excessively high or low ambient temperatures pose a significant challenge to the air conditioning systems of rail transit vehicles. Operating air conditioning in extreme environments not only faces the pressure of extreme temperatures, which can easily cause the system to shut down during operation, but also means that the system often needs to operate at full power to achieve the desired cooling effect, thus increasing energy consumption.

[0003] To address the aforementioned issues, patent application number 200320121172.1, "Evaporator for Heat Pumps with Subcooling Section," utilizes condensate water to exchange heat with the refrigerant before it enters the evaporator, achieving pre-cooling of the refrigerant and thus energy savings. However, years of market validation have shown that this patent's application is limited to cooling mode; it offers no effective energy improvement in heat pump heating mode. Therefore, to further address the energy-saving issues of air conditioning in rail transit vehicles, this paper proposes addressing the fresh air load—a crucial load source in rail transit vehicle air conditioning systems—to achieve energy savings and gradually respond to low-carbon and environmental protection policies. Utility Model Content

[0004] To address the technical problems in the existing technology, this utility model provides a heat pump air conditioning system for rail transit vehicles. It has a simple structure, low cost, and effectively recovers the cold / heat energy of the exhaust air inside the vehicle, thereby improving the cooling effect of the air conditioning.

[0005] To solve the above-mentioned technical problems, this utility model provides a heat pump air conditioning system for rail transit vehicles, which adopts the following technical solution: A heat pump air conditioning system for rail transit vehicles includes a housing, which comprises an indoor cavity and an outdoor cavity. The indoor cavity and the outdoor cavity are connected by a pipeline to form a refrigerant circulation path. The system also includes a fresh air cavity, which includes a first fresh air inlet, a first fresh air outlet, a waste air inlet, and a waste air outlet, all of which are respectively connected to a total heat exchanger. Fresh air and waste air undergo cross-heat exchange within the total heat exchanger. The first fresh air outlet is connected to a first fresh air duct. A second fresh air inlet is also provided on the housing, which is connected to a second fresh air duct. The first and second fresh air ducts either merge or are separately connected to the indoor cavity.

[0006] Furthermore, an evaporator fan is installed inside the indoor cavity, and a fresh air valve is installed at the first fresh air inlet or the first fresh air outlet.

[0007] Furthermore, when the air conditioning system is in cooling or heating mode, the fresh air valve and evaporator fan are open, and fresh air from outside enters the indoor cavity through the first fresh air inlet and the second fresh air inlet respectively; when the air conditioning system is in ventilation mode, the fresh air valve is closed, the evaporator fan is turned on, and fresh air from outside enters the indoor cavity through the second fresh air inlet.

[0008] Furthermore, the waste exhaust air inlet is connected to the waste exhaust unit through the waste exhaust air duct, which is a waste exhaust air duct.

[0009] Furthermore, a mixing zone is provided inside the interior cavity, which is connected to the vehicle interior through a return air vent. The first fresh air duct and the second fresh air duct either merge or are connected to the mixing zone separately.

[0010] Furthermore, a temperature sensor is provided on the housing to detect the ambient temperature and control whether the fresh air treatment function is activated.

[0011] Furthermore, the total heat exchanger has a hexagonal cross-section, with the top and bottom surfaces being planes. Fresh air is introduced from an inclined surface adjacent to the top surface and exits from the opposite side, while waste air is introduced from an inclined surface adjacent to the top surface and exits from the opposite side, forming an X-shaped exchange channel.

[0012] Furthermore, the internal core material of the total heat exchanger is graphene.

[0013] Furthermore, the total heat exchanger is provided with a frame made of plastic material.

[0014] In summary, the heat pump air conditioning system for rail transit vehicles provided by this utility model has the following advantages compared with the prior art: By installing a total heat exchanger, a fresh air fan, and an exhaust fan, the exhaust air that was originally discharged outdoors is diverted to the fresh air path with the total heat exchanger, where it exchanges heat with the fresh air flowing through the total heat exchanger. This effectively recovers the cold / heat of the exhaust air, improves the heat exchange effect of the evaporator, and thus enhances the cooling capacity of the air conditioning system, increases the energy efficiency ratio of the air conditioning system, and reduces the energy consumption of the air conditioning system.

[0015] By integrating the exhaust function into the air conditioning system, fresh air can be treated. This not only integrates the exhaust unit designed into the original vehicle body, but also treats only the fresh air without modifying the air conditioning components. Furthermore, it can demonstrate energy-saving effects for both cooling and heating functions.

[0016] By using a total heat exchanger as a medium, the exhaust air and fresh air come into indirect contact, and heat exchange is achieved through indirect contact. This makes the overall structure of the device simpler, easier to install, and easier to modify based on existing air conditioning systems, resulting in low modification costs. The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the overall structure of the air conditioning system of this utility model; Figure 2 This is a schematic diagram of the working principle of the total heat exchanger of this utility model; Figure 3 This is a schematic diagram of the overall structure of the total heat exchanger of this utility model; Figure 4 This is a schematic diagram of the internal structure of the total heat exchanger of this utility model; Figure 5 This is a front view of the core of the total heat exchanger of this utility model; In the picture: 1. Compressor; 2. Evaporator fan; 3. Condenser; 4. Evaporator; 5. First fresh air fan; 6. Total heat exchanger; 61. Frame; 62. Core; 7. Fresh air valve II; 8. Expansion valve; 9. Fresh air valve I; 10. Condenser fan; 11. Waste exhaust fan; 12. Waste exhaust valve.

[0019] It should be noted that the accompanying drawings and text description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0021] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" 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.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] This utility model provides a heat pump air conditioning system for rail transit vehicles, including a housing, which includes an indoor cavity and an outdoor cavity. The indoor cavity and the outdoor cavity are connected by a pipeline to form a refrigerant circulation path. It also includes a fresh air cavity, which includes a first fresh air inlet, a first fresh air outlet, a waste air inlet, and a waste air outlet, all of which are respectively connected to a total heat exchanger 6. Fresh air and waste air undergo cross-heat exchange within the total heat exchanger 6. The first fresh air outlet is connected to a first fresh air duct. The housing is also provided with a second fresh air inlet, which is connected to a second fresh air duct. The first fresh air duct and the second fresh air duct either merge or are separately connected to the indoor cavity.

[0024] This utility model provides a heat pump air conditioning system for rail vehicles, including a housing, which is divided into an indoor cavity, a compressor cavity, and a condenser cavity by a partition or similar structure. The air conditioning system also includes a compressor 1, an evaporator 4, an expansion valve 8, and a condenser 3 connected by pipelines.

[0025] like Figure 1 As shown, the casing is provided with the following components from left to right: The interior cavity is equipped with an evaporator 4 and an evaporating fan 2, which are connected to the interior of the carriage through a duct to provide the carriage with heat-exchanged air, thereby achieving cooling or heating in the carriage, as well as regular ventilation. The fresh air chamber has a built-in total heat exchanger 6, which is connected to the fresh air and waste exhaust devices to realize heat exchange between some of the fresh air and waste exhaust air, thereby improving the heat exchange efficiency of the air conditioning system. The outdoor cavity is used to house the compressor 1 and the condenser 3. In this embodiment, there are two condensers 3, which are located on both sides of the compressor 1 and are equipped with condenser fans 10. In practical applications, the relative positions of the compressor 1 and the condenser 3 can be set as needed.

[0026] An expansion valve 8 is also installed between the compressor 1 and the evaporator 4.

[0027] Compressor 1 is used in the heat pump air conditioning system to compress the refrigerant; the expansion valve assembly is used for refrigerant throttling, cooling and depressurizing the refrigerant; the evaporator assembly serves as the medium for the refrigerant to absorb heat from the air; the condenser assembly serves as the heat dissipation medium for the refrigerant discharged from compressor 1; the total heat exchanger, installed at the fresh air inlet, serves as the medium for heat exchange between exhaust air and fresh air, realizing the functions of pre-cooling the fresh air during cooling to reduce the heat load, and preheating the fresh air during heating to reduce the cooling load. The total heat exchanger does not use refrigerant and is made of environmentally friendly materials.

[0028] The air conditioning system has two different fresh air paths. During seasons when only ventilation is needed, the total heat exchanger 6 is not required, and fresh air is absorbed through the conventional fresh air path for rail vehicles. During seasons requiring cooling or heating, fresh air is absorbed through the fresh air inlet of the total heat exchanger 6. Because the total heat exchanger 6 has significant resistance, an induced draft fan and dampers are required in this fresh air path to control airflow. This invention has a simple structure and can effectively recover the cold and heat of exhaust air during the air conditioning season, reducing the cooling and heating load on the fresh air, improving the heat exchange effect of the air conditioning system, and increasing the energy efficiency ratio of the air conditioning system.

[0029] The total heat exchanger is independent of the air conditioning system and is housed in a separate fresh air chamber. As a single component, the internal core 62 can be made of materials such as fiber paper, graphene, or metal to improve heat exchange efficiency. The external frame 61 is made of a plastic material to reduce overall weight. The ventilation path of the internal core 62 is an X-shaped exchange channel, with exhaust air on one side and fresh air on the other. A fan draws air in, causing the two air sources with different temperatures to exchange heat within the total heat exchanger, thus pre-cooling or preheating the fresh air.

[0030] like Figures 1 to 5As shown, this utility model provides a heat pump air conditioning system for rail transit vehicles. Heat exchange between fresh air and exhaust air occurs in the fresh air cavity. A first fresh air fan 5, an exhaust fan 11, and a total heat exchanger 6 are installed in the fresh air cavity. A first fresh air inlet is provided in the fresh air cavity, communicating with the environment outside the casing. A first fresh air outlet is connected to the indoor cavity through a first fresh air duct. An exhaust air inlet is connected to the exhaust air duct and the exhaust air device. The first fresh air inlet, first fresh air outlet, exhaust air inlet, and exhaust air outlet are respectively connected to the corresponding air outlets of the total heat exchanger 6. This allows the fresh air and exhaust air to undergo sufficient heat exchange after passing through the total heat exchanger 6. The exhaust air is then discharged outside the casing, and the fresh air enters the indoor cavity through the first fresh air duct.

[0031] A return air vent is also provided in the interior cavity. A further return air vent is located in the mixing zone of the interior cavity. In the mixing zone, the fresh air and the return air are mixed and then enter the carriage through the evaporator 4 for heat exchange.

[0032] The first fresh air fan 5 is installed at any position at the first fresh air inlet, the first fresh air outlet, or the first fresh air duct to guide fresh air into the fresh air cavity; the waste exhaust fan 11 is installed at any position at the waste exhaust inlet or the waste exhaust duct to introduce waste exhaust air from the waste exhaust device into the fresh air cavity.

[0033] The first fresh air unit 5 and the waste exhaust fan 11 guide the fresh air and waste exhaust air through the total heat exchanger 6. After absorbing the heat / cooling energy of the fresh air through the total heat exchanger 6, the waste exhaust air is directly discharged into the air. The heat / cooling energy of the fresh air is absorbed by the waste exhaust air and, guided by the first fresh air unit 5, combines with the return air of the air conditioner to form a mixed airflow, which flows through the evaporator 4 and is discharged into the passenger room to provide cooling or heating functions for the passengers in the passenger room.

[0034] like Figure 1 As shown, in this embodiment, the air conditioning system adopts an integrated air conditioning unit structure, consisting of an indoor cavity, an outdoor cavity, and a fresh air cavity. The indoor cavity and the outdoor cavity are connected by pipes to form a refrigerant circulation path. An evaporator 4, an evaporator fan 2, an expansion valve 8, etc. are installed in the indoor cavity; a condenser 3, a condenser fan 10, a compressor 1, etc. are installed in the outdoor cavity. A heat dissipation grille is provided on the shell of the outdoor cavity for heat dissipation of components such as the condenser 3 and the compressor 1. The condenser 3 can be a shell-and-tube heat exchanger, a finned tube heat exchanger, etc.; a first fresh air fan 5, a total heat exchanger 6, an exhaust fan 11, etc. are installed in the fresh air cavity.

[0035] In this embodiment, the first fresh air fan 5, the total heat exchanger 6, and the waste exhaust fan 11 are respectively installed inside the fresh air cavity. The fresh air is guided by the first fresh air fan 5 and flows through the total heat exchanger 6, while the waste exhaust fan is guided by the waste exhaust fan 11 and flows through the total heat exchanger, so that the two exchange heat in the total heat exchanger 6.

[0036] Furthermore, a second fresh air inlet is provided on the inner cavity side of the casing, and the second fresh air inlet is connected to the inner cavity through a second fresh air duct. Preferably, the second fresh air duct merges with the first fresh air duct before connecting to the inner cavity; more preferably, it connects to the mixing zone of the inner cavity. In practical applications, the first fresh air duct and the second fresh air duct can be connected to the inner cavity separately.

[0037] A fresh air valve I9 ​​is ​​installed at the first fresh air inlet to control the opening and closing of the first fresh air inlet, thereby realizing the flow of fresh air into the new inner cavity. A fresh air valve II7 is installed at the second fresh air inlet to control the opening and closing of the second fresh air inlet.

[0038] like Figure 2 and Figure 3 As shown, in this embodiment, the first fresh air unit 5 is not directly connected to the total heat exchanger 6 and the waste exhaust fan 11. Furthermore, a fresh air valve I9 ​​and a waste exhaust valve 12 need to be installed in the fresh air cavity to realize the function of changing the fresh air path and adjusting the waste exhaust air volume during non-air conditioning seasons.

[0039] During the non-air conditioning season, when the air conditioning system is in ventilation mode, close the fresh air valve I9 ​​so that fresh air can enter the indoor cavity directly through the regular fresh air path via the fresh air valve II7 without being processed by the total heat exchanger 6.

[0040] During the air conditioning season, when the air conditioning system is in cooling or heating mode, to handle fresh air, fresh air valve II7 is closed and fresh air valve I9 ​​is ​​opened. Simultaneously, by adjusting the opening of exhaust air valve 12, heat exchange between fresh air and exhaust air is achieved under conditions of consistent airflow. If necessary, both fresh air valves can be opened simultaneously in cooling or heating mode, and fresh air control can be achieved by adjusting their openings.

[0041] In this embodiment, the second fresh air inlet is located on the side wall of the housing on the interior cavity side, and the first fresh air inlet is located on the side wall of the housing of the fresh air cavity. By adjusting the opening of their respective fresh air valves, the fresh air treatment under the heat exchange mode (cooling and heating mode) and the fresh air path switching under the ventilation mode can be realized. In the ventilation mode, there is no need to perform heat exchange between fresh air and exhaust air, avoiding unnecessary heat exchange and causing fluctuations in the vehicle interior temperature.

[0042] In this embodiment, the decision to activate the fresh air handling unit, i.e., the selection of the fresh air path, primarily relies on the temperature detected by an ambient temperature sensor located near the fresh air inlet on the outside of the air conditioner casing. Based on the temperature feedback from the sensor, a suitable ambient temperature can be set in the controller to activate the fresh air handling unit. For example, when the ambient temperature reaches 30°C, the air conditioner can activate the fresh air handling unit, allowing fresh air and exhaust air to pass through the total heat exchanger, thereby generating heat exchange between them, helping to improve the air conditioner's cooling capacity and reduce energy consumption. When the ambient temperature is below 30°C, or when only the air conditioner needs to operate in ventilation mode, the fresh air handling unit is not activated, and the fresh air simply passes through the conventional fresh air path.

[0043] Considering the specific usage of air conditioning in rail transit vehicles, it is recommended that the first fresh air unit 5, the waste exhaust fan 11, the total heat exchanger 6, etc., be connected with bolts with appropriate torque and marked with anti-loosening marks.

[0044] like Figures 2 to 5 As shown, the total heat exchanger 6 provided in this embodiment has a hexagonal cross-section and a certain length. The top and bottom surfaces of the total heat exchanger 6 are flat to facilitate installation inside the shell.

[0045] The casing is equipped with an X-shaped heat exchange channel, enabling X-shaped cross-heat exchange between fresh air and exhaust air. For example... Figure 2 As shown, fresh air is introduced from the left inclined surface adjacent to the top surface, and correspondingly, it is discharged from the right inclined surface. Exhaust air is introduced from the right inclined surface adjacent to the top surface, and correspondingly, it is discharged from the left inclined surface. The exhaust air and the inlet air form an X-shaped exchange channel inside the total heat exchanger 6.

[0046] Configure the total heat exchanger 6 as follows: Figure 2 The structural form shown can facilitate assembly with the shell, extend the heat exchange path of fresh air and exhaust air in the total heat exchanger 6, improve heat exchange efficiency, and reduce the height of the entire total heat exchanger 6, thereby reducing the shell and the overall height of the air conditioning system.

[0047] As mentioned above, Figure 4 As shown, the total heat exchanger 6 includes an outer frame 61 made of plastic material and an inner core 62 including multiple heat exchange layers made of materials such as graphene. Fresh air and exhaust air pass between adjacent heat exchange layers and achieve heat exchange between fresh air and exhaust air through the heat exchange layers.

[0048] The core 62 of the total heat exchanger 6 includes multiple heat exchange layers arranged in parallel, such as... Figure 5As shown, the cross-section of each heat exchange layer is a zigzag shape, including the middle horizontal section, the upper zigzag section on the left side of the horizontal section, and the lower zigzag section on the right side. The zigzag surface of the heat exchange layer is a zigzag shape, including the middle horizontal section, the upper zigzag section on the left side, and the lower zigzag section on the right side. Its main function is to adapt to the thinner models of rail vehicle air conditioners and the limited air inlet and outlet area of ​​the total heat exchanger. It is made into a diamond-shaped cross-section, and it can enable reverse heat exchange between the inlet and outlet air to improve heat exchange efficiency.

[0049] The rail vehicle heat pump air conditioning system provided by this utility model has the following advantages compared with the prior art: This device is compatible with single-cooling or heat pump air conditioners. Through the installation of a total heat exchanger, a first fresh air unit, and an exhaust fan, the exhaust air that was originally discharged outdoors is guided to flow through the total heat exchanger to exchange heat with the fresh air, thereby reducing the fresh air load. This effectively realizes the recovery of the cold / heat of the exhaust air, improves the cooling / heating capacity of the air conditioning system, increases the energy efficiency ratio of the air conditioning system, and reduces the energy consumption of the air conditioning system.

[0050] This device, through the setting of two sets of fresh air paths, can ensure the operation of the regular fresh air path during the non-air-conditioning season. If only the ventilation mode needs to be run during the non-air-conditioning season, the regular fresh air path can be considered, without passing through the fresh air handling unit, and the first fresh air unit can be shut down, which can reduce energy consumption and ensure the ventilation volume of the guest room. During the air-conditioning season, when the cooling or heating mode needs to be turned on, the fresh air can be pre-treated by passing through the fresh air handling unit. Moreover, the core of the total heat exchanger is made of paper or graphene material, which is easy to replace and has good heat exchange capacity.

[0051] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. The implementation schemes in the above embodiments can be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A heat pump air conditioning system for rail transit vehicles, comprising a housing, the housing including an indoor cavity and an outdoor cavity, wherein the indoor cavity and the outdoor cavity are connected by a pipeline to form a refrigerant circulation path, characterized in that: It also includes a fresh air cavity, which includes a first fresh air inlet, a first fresh air outlet, a waste air inlet, and a waste air outlet, all of which are connected to a total heat exchanger. Fresh air and waste air undergo cross-heat exchange within the total heat exchanger. The first fresh air outlet is connected to a first fresh air duct. A second fresh air inlet is also provided on the shell, which is connected to a second fresh air duct. The first and second fresh air ducts either merge or are connected to the indoor cavity.

2. The heat pump air conditioning system for rail transit vehicles as described in claim 1, characterized in that: A fresh air valve I is installed at the first fresh air inlet, and a fresh air valve II is installed at the second fresh air inlet.

3. A heat pump air conditioning system for rail transit vehicles as described in claim 2, characterized in that: When the air conditioning system is in cooling or heating mode, the fresh air valve I is open and the fresh air valve II is closed, and fresh air from the outside enters the indoor cavity through the first fresh air inlet and the second fresh air outlet respectively; when the air conditioning system is in ventilation mode, the fresh air valve I is closed and the fresh air valve II is open, and fresh air from the outside enters the indoor cavity through the second fresh air outlet.

4. A heat pump air conditioning system for rail transit vehicles as described in claim 1, characterized in that: The waste exhaust air inlet is connected to the waste exhaust unit through the waste exhaust air duct, which is the waste exhaust air duct.

5. A heat pump air conditioning system for rail transit vehicles as described in claim 1, characterized in that: The interior cavity is provided with a mixing zone, which is connected to the vehicle interior through a return air vent. The first fresh air duct and the second fresh air duct either merge or are connected to the mixing zone.

6. A heat pump air conditioning system for rail transit vehicles as described in claim 1, characterized in that: The housing is equipped with a temperature sensor that detects the ambient temperature to control whether the fresh air treatment function is activated.

7. A heat pump air conditioning system for rail transit vehicles as described in any one of claims 1 to 6, characterized in that: The total heat exchanger has a hexagonal cross-section with a flat top and bottom surface. Fresh air is introduced from the inclined surface adjacent to the top surface and exits from the opposite side. Waste air is introduced from the inclined surface adjacent to the top surface and exits from the opposite side, forming an X-shaped exchange channel.

8. A heat pump air conditioning system for rail transit vehicles as described in claim 7, characterized in that: The internal core material of the total heat exchanger is graphene.

9. The heat pump air conditioning system for rail transit vehicles as described in claim 8, characterized in that: The total heat exchanger is equipped with a frame made of plastic material.

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