Negative pressure coolant filling device

Abstract

The utility model discloses negative pressure cooling liquid filling device, including the casing, the casing lower portion is provided with and connects the filling cover of subsidiary water tank, the casing inside still is provided with air pump, and the air pump's air inlet passes through the filling cover and is communicated with subsidiary water tank inside, and the gas outlet passes through the casing and is communicated with outside environment, the top of casing is provided with the filling mouth, and the casing is provided with the U type pipe, and one end of U type pipe is connected to the filling mouth, and the other end is connected with electric control two -way switch valve, and electric control two -way switch valve is three -way valve, and one export of electric control two -way switch valve is communicated to subsidiary water tank inside through the filling pipeline. The utility model solves the problem of the prior art when operating complex and time -consuming for the commercial vehicle normal pressure filling, and the problem of easy filling insufficient.

Description

Technical Field

[0001] This utility model belongs to the technical field of vehicle coolant filling equipment, specifically relating to a negative pressure coolant filling device. Background Technology

[0002] Currently, in the process of adding coolant to commercial vehicles, OEMs use dedicated vacuum filling devices to add coolant to the vehicle's cooling system after assembly on the final assembly line. Vacuum filling can efficiently and quickly complete the coolant filling without the need for degassing. However, due to its large size, high cost, and complex structure, vacuum filling equipment can only be used by OEMs when vehicles roll off the production line, limiting its application scenarios.

[0003] Furthermore, commercial vehicles, due to their unique operating conditions, require frequent coolant top-ups and engine maintenance. After maintenance, commercial vehicles typically use a method of adding coolant at atmospheric pressure followed by degassing to complete the coolant top-up. However, this method results in an initially low fill rate when the vehicle's cooling system has high resistance, easily leading to insufficient coolant volume, poor cooling effect, and consequently, cylinder scoring, premature wear, and other adverse effects, severely impacting engine lifespan. Moreover, this method involves a lengthy degassing time, and after degassing, coolant must be added to the required volume, making the operation cumbersome and reducing maintenance efficiency. Therefore, atmospheric pressure top-up is complex, time-consuming, and prone to insufficient coolant addition. Utility Model Content

[0004] The purpose of this invention is to provide a negative pressure coolant filling device, which solves the problems of complex operation, long time consumption, and insufficient filling when filling commercial vehicles with normal pressure in the existing technology.

[0005] The technical solution adopted by this utility model is a negative pressure coolant filling device, including a housing, a filling cover connected to an auxiliary water tank is provided at the bottom of the housing, and an air pump is also provided inside the housing. The air pump’s air inlet pipe passes through the filling cover as an air inlet and communicates with the interior of the auxiliary water tank, and the air outlet pipe passes through the housing as an air outlet and communicates with the external environment. The top of the shell is equipped with a filling port, and a U-shaped tube is installed inside the shell. One end of the U-shaped tube is connected to the filling port, and the other end is connected to an electrically controlled two-way switching valve. The electrically controlled two-way switching valve is a three-way valve, and one of the outlets of the electrically controlled two-way switching valve is connected to the interior of the auxiliary water tank through the filling pipeline.

[0006] The present invention is further characterized in that, The bottom of the U-shaped tube is lower than the connection points at both ends, which is used to form a liquid seal when the coolant flows through it.

[0007] The other port of the electrically controlled bidirectional switching valve is connected to a cooling water circuit. After the cooling water flows over the surface of the air pump, it merges with the filling pipeline.

[0008] A temperature sensor is installed on the surface of the air pump. The temperature sensor is attached to the surface of the air pump housing and is connected to the control terminal of the electronically controlled bidirectional switching valve via a signal line.

[0009] The housing contains a battery, which is connected to an air pump, a temperature sensor, and an electronically controlled bidirectional switching valve via wiring.

[0010] The top of the housing is also equipped with an air pump switch that controls the start and stop of the air pump. The air pump switch is electrically connected to the battery and the air pump.

[0011] The air pump is a miniature vacuum pump, and its operating voltage is matched with the battery voltage.

[0012] The U-tube is made of transparent or semi-transparent corrosion-resistant material, and its wall is marked with graduations to indicate the lowest liquid level.

[0013] The beneficial effects of this utility model are: (1) The negative pressure coolant filling device of this utility model is connected to the vehicle's auxiliary water tank through the filling cap, and the cooling system of the whole vehicle is kept in a negative pressure state through the internal air pump, forming a pressure difference similar to vacuum filling, which ensures that the initial filling amount can meet the application requirements of the whole vehicle during the filling process, and reduces the degassing time during traditional atmospheric pressure filling.

[0014] (2) The negative pressure coolant filling device of this utility model is also provided with a cooling water circuit inside the shell to cool the air pump. During the filling process of the device, once the temperature sensor detects that the temperature of the air pump surface is higher than the set threshold, the electronically controlled bidirectional switching valve will switch the valve to introduce the filled coolant into the space where the air pump is located, and flow through the air pump surface to cool it. After cooling, the coolant returns to the cooling water circuit and enters the auxiliary water tank, ensuring that the air pump can work efficiently and stably for a long time during the filling process, thereby maintaining the negative pressure state.

[0015] (3) The negative pressure coolant filling device of this utility model is small in size, easy to carry, and highly adaptable. It can be used in different working environments. Compared with the traditional atmospheric pressure filling method, it provides a pressure difference, which enables the filling to be completed quickly, reduces the degassing time, shortens the overall filling operation time, and improves the operation efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the negative pressure coolant filling device of this utility model.

[0017] In the diagram, 1. Filling cap, 2. Housing, 3. Air inlet, 4. Air pump, 5. Air outlet, 6. Cooling water circuit, 7. Temperature sensor, 8. Air pump switch, 9. Battery, 10. Electronically controlled two-way switching valve, 11. U-tube, 12. Filling port, 13. Filling pipeline. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Example 1 This utility model relates to a negative pressure coolant filling device, such as... Figure 1 As shown, the housing 2 serves as the supporting carrier for the overall structure. The housing 2 integrates the core components of the device into a compact unit, adapting to the mobile use requirements in commercial vehicle maintenance scenarios. A filling cap 1 is located at the bottom of the housing 2, corresponding to the top filling position of the auxiliary water tank. The filling cap 1 is securely connected to the auxiliary water tank through a suitable connection structure. At the same time, the filling cap 1 has a sealing function, which can prevent the direct communication between the inside of the auxiliary water tank and the outside atmosphere after connection, providing a sealed foundation for the subsequent construction of a negative pressure environment.

[0020] An air pump 4 is installed inside the housing 2. The air pump 4 is fixed in a suitable position inside the housing 2 to ensure that it does not shake excessively during operation. One end of the air pump 4's air inlet pipe is connected to the air inlet 3 of the air pump 4, and the other end extends through the filler cap 1 to the inside of the auxiliary water tank, so as to directly contact the space inside the auxiliary water tank to draw air from the auxiliary water tank and the vehicle's cooling system. One end of the air pump 4's air outlet pipe is connected to the air outlet 5 of the air pump 4, and the other end extends through the side wall of the housing 2 to the external environment, so as to directly discharge the drawn air outside the device. The combination of air intake through the air inlet pipe and air exhaust through the air outlet pipe provides power for the formation of negative pressure in the cooling system.

[0021] A filling port 12 is provided on the top of the housing 2, serving as the inlet for coolant injection, facilitating the operator to pour coolant into the device. A U-shaped tube 11 is also installed inside the housing 2. One end of the U-shaped tube 11 is connected to the bottom of the filling port 12, allowing coolant to flow directly into the U-shaped tube 11 after being injected through the filling port 12. The other end of the U-shaped tube 11 is connected to an electrically controlled bidirectional switching valve 10, a three-way valve capable of switching the coolant flow direction. One outlet of the electrically controlled bidirectional switching valve 10 is connected to a filling pipeline 13, the other end of which extends into the auxiliary water tank. This allows the coolant flowing through the U-shaped tube 11 to the electrically controlled bidirectional switching valve 10 to smoothly enter the auxiliary water tank through the filling pipeline 13, completing the coolant filling process.

[0022] In actual filling operation, the device is first connected and sealed to the auxiliary water tank through the filling cap 1. Then, coolant is injected into the filling port 12. The coolant will first fill the U-shaped tube 11, further enhancing the sealing effect of the auxiliary water tank. After the air pump 4 is started, the air inlet pipe draws air from the auxiliary water tank and discharges the air through the air outlet 5, so that a negative pressure is formed in the auxiliary water tank. The external pressure pushes the coolant in the filling port 12 to flow into the auxiliary water tank along the U-shaped tube 11, the electrically controlled two-way switching valve 10 and the filling pipeline 13, realizing the core function of negative pressure filling.

[0023] Example 2 This utility model relates to a negative pressure coolant filling device, such as... Figure 1 As shown, it includes a housing 2, a filling cover 1 connected to the auxiliary water tank is provided below the housing 2, and an air pump 4 is also provided inside the housing 2. The air inlet pipe of the air pump 4 passes through the filling cover 1 as an air inlet 3 and communicates with the interior of the auxiliary water tank, and the air outlet pipe passes through the housing 2 as an air outlet 5 and communicates with the external environment. The top of the shell 2 is provided with a filling port 12, and a U-shaped tube 11 is provided inside the shell 2. One end of the U-shaped tube 11 is connected to the filling port 12, and the other end is connected to an electrically controlled bidirectional switching valve 10. The electrically controlled bidirectional switching valve 10 is a three-way valve, and one of the outlets of the electrically controlled bidirectional switching valve 10 is connected to the interior of the auxiliary water tank through the filling pipeline 13.

[0024] Furthermore, the bottom bend of the U-shaped tube 11 is positioned lower than the connection ports at both ends with the filling port 12 and the electrically controlled bidirectional switching valve 10. This height difference structure provides the necessary conditions for the formation of the liquid seal.

[0025] In the initial stage of the actual filling operation, when the operator injects coolant into the filling port 12, the coolant flows into the pipe along one end of the U-shaped tube 11. Under the action of gravity, it first accumulates at the bottom bend of the U-shaped tube 11. As the coolant is continuously injected, the liquid level gradually rises and spreads to both ends until it fills the entire cavity of the U-shaped tube 11. At this time, the coolant at the bottom of the U-shaped tube 11 and in the cavity forms a closed liquid barrier, namely a "liquid seal". This liquid seal can effectively block the communication path between the internal space of the auxiliary water tank and the outside atmosphere through the filling port 12. Together with the sealing connection between the filling cap 1 and the auxiliary water tank, it creates a sealed environment inside the auxiliary water tank.

[0026] This liquid seal structure is a key prerequisite for the device to achieve negative pressure filling: when the air pump 4 starts, its air inlet 3 will draw air from the auxiliary water tank. If there is no liquid seal formed by the U-shaped tube 11, outside air will enter the auxiliary water tank in the opposite direction from the filling port 12, resulting in the inability to form a stable negative pressure. The presence of the liquid seal ensures that the pressure in the auxiliary water tank continues to decrease when the air pump 4 draws air, thereby forming a stable negative pressure. This provides power for the coolant to flow smoothly into the auxiliary water tank along the filling pipeline 13, while preventing outside air from entering the cooling system during the filling process. This reduces the workload and time of the subsequent degassing process, which is in line with the device's design goal of solving the problems of long degassing and insufficient filling during atmospheric pressure filling.

[0027] Furthermore, the electrically controlled bidirectional switching valve 10, as a three-way valve, is connected to the filling pipeline 13 through one valve port, and its other valve port is firmly connected to the cooling water circuit 6 through a special sealing connector. The connection part adopts a suitable sealing structure to ensure that the coolant does not leak during the flow process, and provides a sealing guarantee for the normal operation of the cooling water circuit.

[0028] The overall routing of the cooling water circuit 6 is designed around the heat dissipation requirements of the air pump 4. After being led out from the corresponding valve port of the electronically controlled bidirectional switching valve 10, it is arranged along the surface of the air pump 4, so that the flowing coolant can fully absorb the heat generated by the air pump 4 during operation, effectively reduce the surface temperature of the air pump 4, and avoid the air pump 4 from experiencing performance degradation or failure due to excessive temperature caused by long-term high-frequency operation.

[0029] After cooling the air pump 4, the cooling water passage 6 extends into the lower part of the housing 2, eventually merging with the filling pipe 13 near the filling cap 1. A suitable connection structure is used at the merging point to ensure that coolant can flow smoothly from the cooling water passage 6 into the filling pipe 13, merging with the coolant in the filling pipe 13 before entering the auxiliary water tank through the filling cap 1.

[0030] This connection structure not only effectively cools the air pump 4, ensuring its stable operation, but also allows the coolant involved in heat dissipation to directly enter the auxiliary water tank through the convergence design of the cooling water circuit 6 and the filling pipe 13, eliminating the need for an additional return pipe. This simplifies the internal structure of the device and avoids waste of coolant, aligning with the device's design goal of balancing negative pressure filling efficiency with the heat dissipation stability of core components. It solves the problem of insufficient heat dissipation capacity and difficulty in long-term stable operation of small air pumps due to size limitations.

[0031] Example 3 This utility model relates to a negative pressure coolant filling device, such as... Figure 1 As shown, it includes: Housing 2, housing 2 is provided with a filling cap 1 for sealing connection with the vehicle's auxiliary water tank; A negative pressure generating module, housed within the housing 2, is used to create a negative pressure by evacuating the vehicle's cooling system through the filler cap 1; and a cooling module, thermally connected to the negative pressure generating module, is used to guide the coolant flowing through the device to actively dissipate heat from the negative pressure generating module.

[0032] Furthermore, the negative pressure generating module includes an air pump 4, which has an air inlet 3 communicating with the outside and an air outlet 5 communicating with the inside of the filling cap 1. The cooling module includes a cooling water channel 6 that is coiled or covered on the surface of the air pump 4, a temperature sensor 7 for detecting the temperature of the air pump 4, and an electrically controlled bidirectional switching valve 10 controlled by the temperature sensor 7. The housing 2 is also provided with a filling port 12 for connecting to an external coolant source, and a filling pipe 13 with one end connected to the filling port 12 and the other end connected to the filling cap 1. An electrically controlled bidirectional switching valve 10 is provided on the filling pipe 13 to selectively guide the flowing coolant to the inlet end of the cooling water circuit 6 or directly to the filling cap 1.

[0033] The electrically controlled bidirectional switching valve 10 is a three-way solenoid valve with one inlet and two outlets; The inlet is connected to a U-shaped tube 11 from the filling port 12. The bottom of the U-shaped tube 11 is lower than the connection points at both ends to form a liquid seal when the coolant flows through it. The first outlet is directly connected to the filling cap 1 through the filling pipe 13, and the second outlet is connected to the inlet of the cooling water circuit 6 through a pipe. The outlet of cooling water circuit 6 leads to the filling cap 1.

[0034] Furthermore, the temperature sensor 7, as the core component for temperature monitoring of the air pump 4, is specifically set on the outer surface of the air pump 4, and its attachment position precisely corresponds to the main heat-generating areas of the air pump 4 during operation, such as the motor housing and the outer side of the core working components, to ensure that the actual surface temperature of the air pump 4 can be captured in real time and accurately, avoiding temperature monitoring delays or data distortion due to installation position deviations, and providing a reliable temperature basis for subsequent cooling control.

[0035] A stable connection is established between the temperature sensor 7 and the electrically controlled bidirectional switching valve 10 via a signal line. The signal line is arranged along a pre-defined wiring path inside the housing 2 and is secured by clips or slots inside the housing. This prevents interference between the signal line and components such as the air pump 4 and cooling water circuit 6, and also prevents the signal line from loosening or breaking due to device movement or vibration of the air pump 4, ensuring the continuity and stability of temperature signal transmission. One end of the signal line is connected to the signal output terminal of the temperature sensor 7, and the other end is directly connected to the control terminal of the electrically controlled bidirectional switching valve 10, forming a complete linkage path of "temperature monitoring - signal transmission - valve control".

[0036] After the air pump 4 starts running, the temperature sensor 7 continuously monitors its casing temperature. When the temperature of the air pump 4 does not reach the preset threshold, the temperature sensor 7 does not send a switching signal, the electrically controlled bidirectional switching valve 10 remains in its initial open state, and the coolant flows into the auxiliary water tank only through the filling pipe 13, ensuring that the normal filling process is not disturbed. When the temperature of the air pump 4 rises to the threshold due to long-term operation or high-frequency use, the temperature sensor 7 immediately converts the monitored high temperature signal into an electrical signal, which is transmitted in real time to the control terminal of the electrically controlled bidirectional switching valve 10 through the signal line.

[0037] Upon receiving a high-temperature signal, the electrically controlled bidirectional switching valve 10 quickly switches its internal pathway, redirecting the coolant flow from the filling pipe 13 to the cooling water path 6. As the coolant flows through the cooling water path 6 and passes over the surface of the air pump 4, it absorbs heat, thus cooling the air pump 4 and preventing performance degradation or failure due to high temperatures. The entire process requires no manual intervention and relies entirely on the automatic linkage between the temperature sensor 7 and the electrically controlled bidirectional switching valve 10. This ensures both the long-term stable operation of the air pump 4 and the continuity of the negative pressure filling function, aligning with the design goal of addressing the risk of high-temperature air pump failure and improving reliability.

[0038] Example 4 Based on Embodiment 3 above, this embodiment has a battery 9 installed inside the housing 2 of this utility model. The battery 9 serves as the core power supply for all electrical components of the device. The installation area inside the housing is usually equipped with a slot or bracket that fits the size of the battery 9. The battery 9 is stably fixed by buckles or fastening components to prevent the battery 9 from shifting or colliding due to vibration or tilt when the device is moved or used in commercial vehicle maintenance sites, thus ensuring the stability of power supply and the safety of the internal structure of the device.

[0039] The power supply lines of the storage battery 9 are specifically divided into three lines, which establish stable electrical connections with the air pump 4, the temperature sensor 7, and the electrically controlled bidirectional switching valve 10, respectively: one line is connected to the power input terminal of the air pump 4, providing the power required for the air pump 4 to operate, ensuring that the air pump 4 can continuously draw air from the auxiliary water tank to create a negative pressure environment; another line is connected to the power interface of the temperature sensor 7, providing the power required for the temperature sensor 7 to monitor, ensuring that the temperature sensor 7 can capture the temperature of the air pump 4 casing in real time and transmit signals; the third line is connected to the control terminal power interface of the electrically controlled bidirectional switching valve 10, providing power for the valve core switching, signal reception and execution of the electrically controlled bidirectional switching valve 10, ensuring that the valve can adjust the passage status in a timely manner according to the signal of the temperature sensor 7.

[0040] This eliminates the device's reliance on an external fixed power source, enabling portable and mobile use thanks to the independent power supply capability of battery 9. It is perfectly suited for scenarios without external power, such as commercial vehicle repair sites and outdoor emergency refueling, solving the problem of limited application scenarios caused by the dependence on a fixed power source for traditional vacuum refueling equipment. Simultaneously, battery 9 provides synchronous power to air pump 4, temperature sensor 7, and electronically controlled bidirectional switching valve 10, ensuring that the three can work together effectively.

[0041] Furthermore, the air pump 4 is a miniature vacuum pump, and its operating voltage is matched with the voltage of the battery 9.

[0042] Example 5 Based on Embodiment 4 above, this embodiment also includes an air pump switch 8 on the top of the housing 2 of this utility model for controlling the start and stop of the air pump 4. The air pump switch 8 is electrically connected to the battery 9 and the air pump 4 through two lines respectively, forming a power supply control circuit of "battery 9-air pump switch 8-air pump 4": one line is connected to the battery 9 to obtain electrical energy, and the other line is connected to the air pump 4 to transmit power signals.

[0043] During operation, the operator presses the air pump switch 8, which connects the circuit and allows the battery 9 to supply power to the air pump 4. The air pump 4 then starts pumping air to create negative pressure. When filling is complete or needs to be paused, pressing the switch again disconnects the circuit and stops the air pump 4. This design allows the operator to flexibly control the pressure according to the filling progress, avoiding idling and power consumption. It aligns with the device's design goals of portability and ease of operation, solving the problem of inconvenient operation of traditional equipment.

[0044] Example 6 Based on Embodiment 5 above, the U-shaped tube 11 of this utility model, as a key component for constructing a liquid seal and ensuring negative pressure injection, is made of transparent or semi-transparent corrosion-resistant material. The transparency / semi-transparency allows operators to intuitively observe the filling status of the coolant inside the tube, confirming whether the coolant fills the tube cavity without disassembling the device, which meets the design requirement of "easy operation" of the device. The corrosion resistance can resist the erosion of chemical components in the coolant, avoiding corrosion and damage to the tube wall after long-term use, which would lead to coolant leakage, and ensuring the structural stability and service life of the U-shaped tube 11.

[0045] The U-shaped tube 11 has specially designed graduation lines on its wall, which precisely correspond to the minimum liquid level required for the formation of the liquid seal. When the operator injects coolant into the filling port 12, the rise of the liquid level can be observed through the transparent / semi-transparent tube wall. When the liquid level reaches the graduation line, it means that the bottom of the U-shaped tube 11 is full of coolant, which can effectively block the connection between the auxiliary water tank and the outside atmosphere, providing a sealed foundation for the air pump 4 to draw air and build a stable negative pressure. If the liquid level does not reach the graduation line, the outside air will enter the auxiliary water tank in reverse due to the incomplete liquid seal, and an effective negative pressure cannot be formed. The graduation line can quickly guide the operator to control the amount of coolant added, avoiding waste due to excessive injection or failure of the liquid seal due to insufficient injection.

[0046] Finally, it should be noted that in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A negative pressure coolant filling device, characterized in that, Includes a housing (2), with a filling cover (1) connected to the auxiliary water tank at the bottom of the housing (2), and an air pump (4) inside the housing (2). The air inlet pipe of the air pump (4) passes through the filling cover (1) as an air inlet (3) and connects to the inside of the auxiliary water tank, and the air outlet pipe passes through the housing (2) as an air outlet (5) and connects to the external environment. The top of the shell (2) is provided with a filling port (12), and a U-shaped pipe (11) is provided inside the shell (2). One end of the U-shaped pipe (11) is connected to the filling port (12), and the other end is connected to an electrically controlled two-way switching valve (10). The electrically controlled two-way switching valve (10) is a three-way valve, and one of the outlets of the electrically controlled two-way switching valve (10) is connected to the interior of the auxiliary water tank through the filling pipeline (13).

2. The negative pressure coolant filling device according to claim 1, characterized in that, The bottom of the U-shaped tube (11) is lower than the connection points at both ends, which is used to form a liquid seal when the coolant flows through it.

3. The negative pressure coolant filling device according to claim 1, characterized in that, The other port of the electrically controlled bidirectional switching valve (10) is connected to a cooling water path (6). After the cooling water path (6) flows through the surface of the air pump (4), it merges with the filling pipeline (13).

4. The negative pressure coolant filling device according to claim 1, characterized in that, A temperature sensor (7) is provided on the surface of the air pump (4). The temperature sensor (7) is attached to the outer surface of the air pump (4) and connected to the control terminal of the electronically controlled bidirectional switching valve (10) through a signal line.

5. The negative pressure coolant filling device according to claim 4, characterized in that, The housing (2) is equipped with a storage battery (9), which is connected to an air pump (4), a temperature sensor (7) and an electronically controlled bidirectional switching valve (10) via wiring.

6. The negative pressure coolant filling device according to claim 5, characterized in that, The top of the housing (2) is also provided with an air pump switch (8) for controlling the start and stop of the air pump (4), and the air pump switch (8) is electrically connected to the battery (9) and the air pump (4).

7. The negative pressure coolant filling device according to claim 5, characterized in that, The air pump (4) is a miniature vacuum pump, and its operating voltage is matched with the voltage of the battery (9).

8. The negative pressure coolant filling device according to claim 1, characterized in that, The U-tube (11) is made of a transparent or semi-transparent corrosion-resistant material, and its wall is provided with scale lines for indicating the lowest liquid level.

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