Waterway structure of vehicle cooling liquid heater and heater

Abstract

The utility model relates to a vehicle cooling liquid heater waterway structure and a heater, which are characterized in that the left side and the right side of the front end of a shell main body are provided with front support cover mounting interfaces, and a rear support cover mounting surface is arranged in the shell main body and close to the rear end; the front ends of two parallel vertical edges of the U-shaped water channel in the shell main body respectively extend to the front support cover mounting interfaces on the two sides, and the rear ends of the two parallel vertical edges extend to the rear support cover mounting surface; the two heating rod front supporting covers are composed of water inlet and outlet pipe parts and heating rod supporting cavity base parts. The two heating rod front support covers are respectively and fixedly arranged at the left and right front support cover mounting interfaces in a sealing manner; the heating rod rear supporting cover is fixedly arranged outside the rear supporting cover mounting surface in a sealing manner; the two heating rods are respectively inserted into the two parallel vertical cavities of the U-shaped water channel at intervals, the front ends of the two heating rods are hermetically inserted and supported in the heating rod supporting cavity seats of the two heating rod front supporting covers, and the rear ends of the two heating rods are hermetically inserted and supported in the left and right heating rod supporting cavity seats of the heating rod rear supporting cover. The structure is good in sealing effect and convenient to maintain.

Description

Technical Field

[0001] The utility model belongs to the technical field of vehicle electric heaters, and particularly relates to a waterway structure and a heater for a vehicle coolant heater. Background Art

[0002] The coolant electric heater is a core component of the ITMS (Integrated Thermal Management System). At present, the main heating methods of vehicle electric heaters are PTC ceramic chip heating, metal film heating, and resistance wire heating. The resistance wire heater has an increasing market share due to its high heating rate. The existing resistance wire heaters mainly adopt double-headed rod heating components, and the main body part of the double-headed rod heating component is spiral-shaped. The overall external dimension of the resistance wire heater adopting the double-headed rod heating component is relatively thick and large, and the gravity is large, making it difficult to meet the requirements of lightweight and miniaturization of the current vehicle-mounted devices, and it is not convenient for the reasonable design and sealing of the waterway of the existing heater, affecting the reliability of the product and being inconvenient for maintenance. Summary of the Utility Model

[0003] Aiming at the deficiencies of the prior art, the utility model provides a waterway structure and a heater for a vehicle coolant heater that are convenient for miniaturization and lightweight of the heater, can achieve a better sealing effect, and are convenient for maintenance.

[0004] One of the above-mentioned purposes of the utility model is realized through the following technical solutions:

[0005] A waterway structure for a vehicle coolant heater, characterized in that it includes a housing, two columnar heating rods, two front support covers for heating rods, and a rear support cover for heating rods;

[0006] The housing is a combined component, composed of a top cover and a housing main body; on the left and right sides of the front end of the housing main body, there are front support cover installation interfaces, the rear end of the housing main body adopts an open structure, and a rear support cover installation surface is arranged inside the housing main body near the rear end; a U-shaped waterway is built in the housing main body, and the front ends of the two parallel vertical sides of the U-shaped waterway respectively extend to the front support cover installation interfaces on both sides, and the rear ends of the two parallel vertical sides of the U-shaped waterway extend to the rear support cover installation surface;

[0007] The two front support covers for heating rods adopt a tube plate structure, which is composed of an inlet and outlet water pipe part and a heating rod support cavity seat part that are arranged in parallel and extend in the opposite direction; the two front support covers for heating rods are respectively detachably and hermetically fixed and installed at the left and right front support cover installation interfaces in a way that the inlet and outlet water pipe parts face outwards;

[0008] The rear support cover for heating rods adopts a cover body structure with heating rod support cavity seats arranged on the left and right; the rear support cover for heating rods is detachably and hermetically fixed and installed outside the rear support cover installation surface of the housing main body in a way that the heating rod support cavity seats face inwards;

[0009] The two columnar heating rods are respectively inserted into the two parallel cavities of the U-shaped water channel at intervals. The front ends of the two columnar heating rods are hermetically inserted and supported in the heating rod support cavity seats of the two front heating rod support covers. The rear ends of the two columnar heating rods are respectively hermetically inserted and supported in the left and right heating rod support cavity seats of the rear heating rod support cover, so as to form a closed flow channel cavity inside the housing.

[0010] Moreover, it also includes two front support cover sealing rings. A front end sealing ring installation groove is provided around the outer periphery of the installation interfaces of the two front support covers. The two front support cover sealing rings are respectively embedded in the two front end sealing ring installation grooves, so that the front heating rod support cover is in sealed contact with the front end of the housing.

[0011] Moreover, it also includes a rear support cover sealing ring; a rear end sealing ring installation groove is provided around the outer periphery of the rear end of the two parallel vertical sides of the U-shaped water channel on the rear support cover installation surface; the rear support cover sealing ring is embedded in the rear end sealing ring installation groove, so that the rear heating rod support cover is in sealed contact with the rear support cover installation surface.

[0012] Moreover, it also includes two front heating rod sealing rings and two rear heating rod sealing rings; an annular groove is provided on the inner hole wall of the heating rod support cavity seat part of the two front heating rod support covers. The two front heating rod sealing rings are respectively embedded in the two annular grooves and are respectively in sealed contact with the front ends of the two heating rods; an annular groove is provided on the inner hole wall of the two heating rod support cavities on the rear heating rod support cover. The two rear heating rod sealing rings are respectively embedded in the two annular grooves and are respectively in sealed contact with the rear ends of the two heating rods.

[0013] The second above-mentioned object of the present invention is achieved by the following technical solution:

[0014] A vehicle coolant heater includes the above-mentioned vehicle coolant heater waterway structure, and also includes a rear cover, a heating rod terminal row, a water temperature sensor, a heating rod temperature sensor, a high-voltage input terminal row, a high-voltage wire harness, a low-voltage connector, an IGBT fixing plate, an insulating shell, an insulating gasket, and a PCBA board;

[0015] An electrical cavity is formed outside the flow channel cavity in the housing main body;

[0016] The high-voltage wire harness and the low-voltage connector are fixedly connected to the part between the two front heating rod support covers at the front end of the housing main body; the top cover and the rear cover are respectively hermetically fixed to the top and the rear end of the housing main body by sealant;

[0017] The PCBA board is fixed at the lower position of the electrical cavity and below the top cover; the IGBT on the PCBA board and the IGBT fixing plate are attached to the heat dissipation platform on the housing main body, and an insulating gasket is provided on the heat dissipation platform, and the insulating shell is installed around the IGBT;

[0018] The high-voltage wiring harness is fixedly connected to the high-voltage input terminal block; the heating rod terminal block is arranged on the outer side of the rear support cover of the heating rod and is fixedly connected to the latter. The heating rod terminals are welded to the lead ends of the two heating rods; the pin ends of the high-voltage input terminal block, the low-voltage connector, and the heating rod terminal block are welded to the PCBA board.

[0019] There are two heating rod temperature sensors, and the two heating rod temperature sensors are electrically connected to the PCBA board through connectors; vertically installed cavities are respectively and vertically arranged above the positions close to the front ends of the two parallel cavities corresponding to the U-shaped water channel on the main body of the housing, and the vertically installed cavities extend upward into the electrical cavity. The two heating rod temperature sensors are respectively and hermetically inserted at the two vertically installed cavities and are fixedly connected to the housing part outside the installation cavity through the sensor mounting seats located at the upper part; a compression spring is arranged between the lower end of the sensor mounting seat and the limiting platform on the heating rod temperature sensor, so that the lower measuring end of the heating rod temperature sensor is in direct contact with the surface of the corresponding heating rod.

[0020] There are two water temperature sensors, and the two water temperature sensors are electrically connected to the PCBA board through connectors; the temperature sensing parts of the two water temperature sensors are respectively installed in two sinking grooves through heat-conducting silicone grease, and the two sinking grooves are respectively arranged on the outer side walls of the front ends of the two parallel cavities of the main body of the housing close to the U-shaped water channel.

[0021] Moreover, it further includes two insulating caps, and the two insulating caps are respectively installed on the outer sides of the two heating rod support cavities of the rear support cover of the heating rod.

[0022] Moreover, it further includes a breathing valve, and the breathing valve is installed at the bottom of the main body of the housing.

[0023] The advantages and positive effects of the present utility model are as follows:

[0024] 1. The present utility model arranges a U-shaped water channel in the housing and cooperates with the two front support covers of the heating rods, the two columnar heating rods, and the rear support cover of the heating rod to form an internally closed flow channel cavity. During the process of the coolant passing through the flow channel cavity, the coolant is heated on both sides successively by the two columnar heating rods. On the premise of meeting the heating performance, the thin, small, and light design of the coolant heater housing can be realized, so as to achieve the goals of miniaturization and light weight of the heater.

[0025] 2. The present utility model detachably installs the two front support covers of the heating rods at the front end of the housing and detachably installs the rear support cover of the heating rod at a position close to the rear end of the housing, and seals and connects them through a sealing ring, realizing the sealing of the head and tail of the flow channel cavity. Once the airtightness of the waterway structure is poor, it can be conveniently disassembled and maintained, and the cost can be saved.

[0026] 3. The utility model adopts a columnar heating rod. Compared with the existing spiral-bent heating rod, the magnesium powder inside the heating rod is evenly distributed, no local hot spots occur, and the heating reliability and heating efficiency are improved. Description of the Drawings

[0027] Figure 1 is a schematic diagram of the overall structure of the vehicle coolant heater;

[0028] Figure 2 is a three-dimensional exploded view of the waterway structure of the vehicle coolant heater;

[0029] Figure 3 is an overall cross-sectional view of the waterway structure of the vehicle coolant heater;

[0030] Figure 4 is a three-dimensional exploded view of the vehicle coolant heater;

[0031] Figure 5 is an exploded view of the electrical part of the coolant heater of the present invention. Detailed Embodiment

[0032] The structure of the utility model will be further described below in conjunction with the drawings and through embodiments. It should be noted that this embodiment is narrative rather than restrictive.

[0033] For a waterway structure of a vehicle coolant heater, please refer to Figures 1 - 5 , and its inventive points are as follows: It includes a housing 1, two columnar heating rods 8, two front support covers 2 for the heating rods, a rear support cover 11 for the heating rods, two front support cover sealing rings 5, two front sealing rings 7 for the front ends of the heating rods, a rear support cover sealing ring 10, two rear sealing rings 9 for the rear ends of the heating rods, etc. The columnar heating rod is a resistive heating rod, and its internal structure refers to the existing heating rod structure with a single-end outlet.

[0034] The housing is a combined part, composed of a top cover 1.2 and a housing main body 1.1. The housing main body is an injection molded part. At the front end of the housing main body, there are front support cover installation interfaces on both the left and right sides, which are used for installing the front support covers. An outer front sealing ring installation groove is provided around the two front support cover installation interfaces for installing the front support cover sealing rings. The rear end of the housing main body adopts an open structure, and a rear support cover installation surface is provided inside the housing main body near the rear end for positioning and installing the rear support cover for the heating rod.

[0035] A U-shaped water channel is provided inside the housing main body. The front ends of the two parallel vertical sides of the U-shaped water channel respectively extend to the front support cover installation interfaces on both sides, and the rear ends of the two parallel vertical sides of the U-shaped water channel extend to the rear support cover installation surface. A rear sealing ring installation groove is provided on the rear support cover installation surface around the rear ends of the two parallel vertical sides of the U-shaped water channel for installing the rear support cover sealing ring.

[0036] The front support cover of the two heating rods adopts a tube sheet structure, which is composed of an inlet and outlet water pipe part 2.1 and a heating rod support cavity seat part 2.2 that are parallel and extend in the reverse direction. Screw through holes are provided at the position of the front support cover of the heating rod near the outer edge for installing screws to achieve the fixed installation of the front support cover of the heating rod. The inner diameter of the heating rod support cavity seat part is consistent with the outer diameter of the front end of the heating rod, and an annular groove is provided on the inner hole wall of the heating rod support cavity seat part for installing the front end sealing ring of the heating rod. The two front support covers of the heating rods are respectively positioned at the left and right front support cover installation interfaces with the inlet and outlet water pipe parts facing outward. Through the front support cover sealing ring embedded in the corresponding front end sealing ring installation groove, the sealing contact with the front end of the housing body is achieved, and through screw fastening, the fixed connection between the front support cover of the heating rod and the housing body is achieved.

[0037] The rear support cover of the heating rod adopts a cover body structure with heating rod support cavity seats arranged on the left and right, and screw through holes are provided at the position of the rear support cover of the heating rod near the outer edge for installing screws to achieve the fixed installation of the rear support cover of the heating rod. The rear support cover of the heating rod is positioned outside the rear support cover installation surface of the housing body with the heating rod support cavity seats facing inward. Through the rear support cover sealing ring embedded in the rear end sealing ring installation groove, the sealing contact with the rear support cover installation surface of the housing body is achieved, and through screw fastening, the fixed connection between the rear support cover of the heating rod and the housing body is achieved. Annular grooves are provided on the inner hole walls of the two heating rod support cavity seats on the rear support cover of the heating rod for installing the rear end sealing rings of the heating rods.

[0038] The two columnar heating rods are respectively inserted into the two parallel cavities of the U-shaped water channel at a set gap. The front ends of the two columnar heating rods are respectively sealed and inserted and supported in the heating rod support cavity seats of the two front support covers of the heating rods through a front end sealing ring of the heating rod. The rear ends of the two columnar heating rods are respectively sealed and inserted and supported in the left and right heating rod support cavity seats of the rear support cover of the heating rod through a rear end sealing ring of the heating rod.

[0039] Through the installation of the above two front support covers of the heating rods, two columnar heating rods, and the rear support cover of the heating rod on the housing body, a closed flow channel cavity 12 is formed inside the housing. The two heating rods are arranged in series in the flow channel cavity. The inlet and outlet water pipes on one front support cover of the heating rod are used as the inlet pipe, and the other is used as the outlet pipe. The coolant that needs to be heated enters the flow channel cavity inside the housing through the inlet pipe. When passing through the gap between the cavity wall of the flow channel cavity and the outer surface of the heating rod, it is heated through the surface of the heating rod. After being heated successively by the two heating rods, finally, the coolant with the required high temperature flows out of the fluid channel through the outlet pipe for use by the heat supply management system.

[0040] To achieve axial limit of the heating rod and prevent axial displacement of the heating rod, an axial limit rubber ring 6 is further provided at the front end of the heating rod within the heating rod support cavity seat of the front support cover of the two heating rods, which contacts the front end face of the heating rod. The rear end of the heating rod is limited by the bottom surface of the heating rod support cavity seat of the rear support cover of the heating rod.

[0041] The above-mentioned columnar heating rod is a single-end lead heating rod, and the lead is taken from the rear end of the heating rod.

[0042] The heater adopting the above-mentioned waterway structure of the vehicle coolant heater, in addition to including the above-mentioned waterway structure of the vehicle coolant heater, further includes a rear cover 13, a heating rod terminal row 14, an insulating cap 15, a water temperature sensor 20, a heating rod temperature sensor 17, a high-voltage input terminal row 19, a high-voltage wire harness 3, a low-voltage connector 4, an IGBT fixing plate 22, an insulating shell 21, an insulating gasket 24, a PCBA board 23, a breather valve 16, etc.

[0043] An electrical cavity is formed outside the flow channel cavity within the housing main body for installing electrical components. Refer to Figure 4 and Figure 5 . The high-voltage wire harness and the low-voltage connector are fixedly connected to the front end of the housing main body between the front support covers of the two heating rods by screws. The breather valve is installed at the bottom of the housing main body to balance the internal and external pressures. The top cover and the rear cover are respectively sealed with the top and rear ends of the housing main body by sealant, thus forming an electrical cavity isolated from the outside. The pin ends of the high-voltage input terminal row, the low-voltage connector, and the heating rod terminal row are welded to the PCBA board together. The high-voltage wire harness is fixedly connected to the high-voltage input terminal row by screws. The heating rod terminal row is arranged outside the rear support cover of the heating rod, and the two are fixedly connected by screws. The heating rod terminals are welded to the lead ends of the two heating rods, thereby forming the electrical connection between the PCBA board, the high- and low-voltage connectors, and the heating rods.

[0044] The high-voltage wire harness of the heater is connected to the vehicle's high-voltage power supply system to provide power, and the low-voltage connector is connected to the vehicle's low-voltage system. The vehicle end uses a 12V low-voltage circuit to control the 400V - 800V high-voltage system to achieve control of the heater.

[0045] Screw through holes are provided at the edges of the PCBA board and are fixed at the lower position of the top cover within the electrical cavity by screws passing through the screw through holes. The IGBT on the PCBA board dissipates heat through the heat dissipation platform on the housing main body, and electrical isolation between the two is achieved through an insulating gasket. To not affect the heat dissipation of the IGBT on the PCBA board, the IGBT on the PCBA board and the IGBT fixing plate are closely attached to the heat dissipation platform on the housing main body by screws. At the same time, to increase the creepage distance between the IGBTs on the PCBA board, an insulating shell is installed around the IGBT.

[0046] To ensure product and personnel safety, in addition to overvoltage, overcurrent and other protection functions, this solution also adds an over-temperature protection function. For example Figure 4 and Figure 5 As shown, this type of heater is provided with a heating rod temperature sensor and a water temperature sensor. Both sensors are electrically connected to the PCBA board through connectors. There are two heating rod temperature sensors. Vertically installed cavities are respectively and vertically provided above the two parallel cavities corresponding to the U-shaped water channel near the front end on the main body of the housing. The vertically installed cavities extend upward into the electrical cavity. The two heating rod temperature sensors are respectively sealed and inserted at the two vertically installed cavities, and are fixedly connected to the housing part outside the installation cavity through a sensor mounting seat located at the upper part by screws. A compression spring is arranged between the lower end of the sensor mounting seat and the limit platform on the heating rod temperature sensor, so that the lower measuring end of the heating rod temperature sensor is in direct contact with the surface of the corresponding heating rod, and the temperature of the heating rod measured in this way is more direct and accurate. There are two water temperature sensors. The temperature sensing parts of the two water temperature sensors are respectively installed in the sinking grooves on the outer side walls of the two parallel cavities of the main body of the housing near the front end of the U-shaped water channel through thermal conductive silicone grease. By measuring the temperature of the housing part corresponding to the sinking grooves, the water temperature at the inlet and outlet can be obtained, and the temperature of the water temperature sensors at the inlet and outlet collected can be directly transmitted to the PCBA board.

[0047] To achieve insulation, the above two insulating caps are respectively installed on the outer sides of the two heating rod support cavity seats of the rear support cover of the heating rod.

[0048] In addition, this heater is also provided with a grounding bolt 18, and the grounding bolt is fixedly installed at the front end of the main body of the housing.

[0049] For the heater provided in this embodiment, the housing is made of metal material, which can well solve the electromagnetic compatibility (EMC) problem of electronic components. In addition, this heater has a small overall volume and light weight; has a variety of protection functions and high product reliability; is applicable to high-voltage platforms of 400V to 800V, and has a wider application range.

[0050] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that: within the spirit of the present invention and the appended claims, various substitutions, changes and modifications are possible. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments and drawings.

Claims

1. A water channel structure of a vehicle coolant heater, characterized in that: It includes a shell, two columnar heating rods, two front support covers of the heating rods, and a rear support cover of the heating rods; The shell is a combination, consisting of a top cover and a shell body; front support cover mounting interfaces are arranged on the left and right sides of the front end of the shell body, the rear end of the shell body adopts an open structure, and a rear support cover mounting surface is arranged in the shell body near the rear end; a U-shaped water channel is built into the shell body, the front ends of the two parallel vertical sides of the U-shaped water channel extend to the front support cover mounting interfaces on both sides respectively, and the rear ends of the two parallel vertical sides of the U-shaped water channel extend to the rear support cover mounting surface; The two heating rod front support covers adopt a tube sheet structure, which is composed of an inlet and outlet water pipe part and a heating rod support cavity seat part that are arranged in parallel and in opposite directions; the two heating rod front support covers are detachably sealed and fixedly installed at the left and right front support cover installation interfaces in a manner that the inlet and outlet water pipe parts are arranged outward; The heating rod rear support cover adopts a cover structure with heating rod support cavity seats arranged on the left and right sides; the heating rod rear support cover is detachably sealed and fixedly installed outside the rear support cover installation surface of the shell body in a manner that the heating rod support cavity seats are arranged inward; The two columnar heating rods are respectively inserted into the two parallel cavities of the U-shaped water channel with a gap, the front ends of the two columnar heating rods are sealed and inserted and supported in the heating rod support cavity seats of the two heating rod front support covers, and the rear ends of the two columnar heating rods are respectively sealed and inserted and supported in the left and right heating rod support cavity seats of the heating rod rear support cover, so that a closed flow channel cavity is formed inside the shell.

2. The water channel structure of the vehicle coolant heater according to claim 1, characterized in that: It also includes two front support cover sealing rings, and a front end sealing ring installation groove is provided on the periphery of the two front support cover installation interfaces. The two front support cover sealing rings are respectively embedded in the two front end sealing ring installation grooves, so that the front support cover of the heating rod is in sealing contact with the front end of the shell.

3. The water channel structure of the vehicle coolant heater according to claim 1, characterized in that: It also includes a rear support cover sealing ring; a rear end sealing ring installation groove is arranged on the periphery of the rear ends of the two parallel vertical sides of the U-shaped water channel on the rear support cover installation surface; the rear support cover sealing ring is embedded in the rear end sealing ring installation groove, so that the rear support cover of the heating rod forms a sealing contact with the rear support cover installation surface.

4. The water channel structure of the vehicle coolant heater according to claim 1, characterized in that: It also includes two heating rod front end sealing rings and two heating rod rear end sealing rings; an annular groove is provided on the inner hole wall of the heating rod support cavity seat part of the two heating rod front support covers, and the two heating rod front end sealing rings are respectively embedded in the two annular grooves and form a sealing contact with the front ends of the two heating rods respectively; annular grooves are provided on the inner hole wall of the two heating rod support cavity seats on the heating rod rear support cover, and the two heating rod rear end sealing rings are respectively embedded in the two annular grooves and form a sealing contact with the rear ends of the two heating rods respectively.

5. A vehicle coolant heater, characterized in that: The vehicle coolant heater water channel structure comprises any one of claims 1 to 4, and further comprises a rear cover, a heating rod terminal block, a water temperature sensor, a heating rod temperature sensor, a high-voltage input terminal block, a high-voltage wiring harness, a low-voltage connector, an IGBT fixing plate, an insulating shell, an insulating gasket, and a PCBA board; An electrical cavity is formed in the housing body outside the flow channel cavity; The high-voltage wiring harness and the low-voltage connector are fixedly connected to the front end of the housing body between the front support covers of the two heating rods; the top cover and the rear cover are respectively sealed and fixed to the top and rear end of the housing body by sealant; The PCBA board is fixed in the electrical cavity at the lower position of the top cover; the IGBT on the PCBA board and the IGBT fixing plate are fitted with the heat dissipation platform on the shell body, and an insulating gasket is arranged on the heat dissipation platform, and the insulating shell is installed around the IGBT; The high-voltage wiring harness is fixedly connected to the high-voltage input terminal block; the heating rod terminal block is arranged on the outside of the rear support cover of the heating rod, and the two are fixedly connected, and the heating rod terminal is welded and connected to the lead ends of the two heating rods; the high-voltage input terminal block, the low-voltage connector, and each pin end of the heating rod terminal block are welded and connected to the PCBA board; There are two heating rod temperature sensors, and the two heating rod temperature sensors are electrically connected to the PCBA board through a connector; vertical installation cavities are respectively vertically arranged at the upper position of the two parallel cavities corresponding to the U-shaped water channel on the shell body near the front end, and the vertical installation cavities extend upward into the electrical cavity; the two heating rod temperature sensors are respectively sealed and inserted in the two vertical installation cavities, and are fixedly connected to the shell part outside the installation cavity through the sensor mounting seat located at the upper part; a compression spring is arranged between the lower end of the sensor mounting seat and the limit platform on the heating rod temperature sensor, so that the lower measuring end of the heating rod temperature sensor is in direct contact with the corresponding heating rod surface; There are two water temperature sensors, which are electrically connected to the PCBA board through a connector; the temperature sensing parts of the two water temperature sensors are respectively installed in two sunken grooves through thermal conductive silicone grease, and the two sunken grooves are respectively arranged on the outer side walls of the front ends of the two parallel cavities on the shell body close to the U-shaped water channel.

6. The vehicle coolant heater according to claim 5, characterized in that: It also includes two insulating caps, which are respectively installed on the outer sides of the two heating rod supporting cavities of the rear supporting cover of the heating rod.

7. The vehicle coolant heater according to claim 5, characterized in that: Also included is a breathing valve, which is installed at the bottom of the housing body.

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