An automobile, a fuel cell stack cooling circuit and an insulation treatment method thereof

Abstract

The present invention discloses an automobile, a fuel cell stack cooling circuit and an insulation treatment method thereof. The insulation treatment method of the fuel cell stack cooling circuit uses the water inlet and the water outlet of the stack as position references respectively, and determines the insulation treatment area for the cooling circuit part within the pipeline length range at a preset length threshold from the position reference; the cooling circuit part at least includes corresponding pipe segments of the inlet pipe connected to the water inlet and the outlet pipe connected to the water outlet. Applying this solution, the optimization of the insulation treatment method can effectively reduce the secondary insulation points, and on the basis of effectively reducing the cost, the insulation reliability can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell cooling, and particularly relates to an automobile, a cooling circuit of a fuel cell stack and an insulation treatment method thereof. Background Art

[0002] When the fuel cell stack is in a working state, it needs to be connected to a cooling circuit to cool down the stack. According to the existing design scheme of the fuel cell stack, the coolant directly contacts the reaction plates of the stack, that is, the coolant directly contacts the high-voltage charged part of the stack. However, after the coolant enters the stack to absorb heat, it needs to circulate and dissipate heat through the cooling pipelines of the whole vehicle, and most of the cooling circuits of the fuel cell stack have multiple branch circuits for thermal management. If the coolant of the stack directly contacts the high-voltage conductors in the stack, it will cause leakage of high-voltage insulation. If the insulation performance of the cooling circuit flowing through the vehicle body ground is low, the insulation of the fuel cell vehicle will be significantly reduced.

[0003] In order to improve the insulation state of the fuel cell vehicle, it is necessary to strengthen the secondary insulation of each link of the stack cooling circuit. The treatment means include replacing the cooling pipelines with rubber materials with better insulation performance, using plastic joints with better insulation for all pipeline joints, and adding secondary insulation rubber pads at all installation points in all circuits and other insulation treatment methods. If all the above means are implemented, the cost of the whole vehicle will increase.

[0004] In addition, the requirements for the production and assembly links of the secondary insulation measures are also very high. Any mistake in any link may lead to the failure of the secondary insulation design scheme. In addition, there are too many secondary insulation points, and it will be very difficult to troubleshoot after problems occur.

[0005] In view of this, it is urgent to find another way to optimize the existing fuel cell stack cooling scheme to overcome the defect of too many secondary insulation points. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides an automobile, a cooling circuit of a fuel cell stack and an insulation treatment method thereof. By optimizing the insulation treatment method, the secondary insulation points can be effectively reduced, and on the basis of effectively reducing the cost, the insulation reliability can be improved.

[0007] The insulation treatment method for the cooling circuit of the fuel cell stack provided by the present invention takes the water inlet and outlet of the stack as the position reference respectively, and determines the insulation treatment area for the part of the cooling circuit within the pipeline length range with a preset length threshold from the position reference; the part of the cooling circuit at least includes the corresponding pipe segments of the inlet pipe connected to the water inlet and the outlet pipe connected to the water outlet.

[0008] Preferably, the cooling circuit portion within the pipeline length range that is a preset length threshold away from the position reference is specifically: the corresponding pipe section of the outlet pipe that is a first pipeline length away from the water outlet and the corresponding pipe section of the inlet pipe that is a second pipeline length away from the water inlet, and the first pipeline length and the second pipeline length satisfy the preset length threshold.

[0009] Preferably, the first pipeline length and the second pipeline length satisfy the following condition:

[0010] In the formula, L0 is the first pipeline length, L8 is the second pipeline length, R min is the minimum value of the insulation resistance of the stack to the ground, σ is the conductivity of the stack coolant, and r0 is the pipe radius of the outlet pipe and the inlet pipe.

[0011] Preferably, the water pump of the cooling circuit is configured at a position on the inlet pipe that is the first pipeline length away from the water inlet, and the thermostat of the cooling circuit is configured at a position on the outlet pipe that is the second pipeline length away from the water outlet; the components of the other cooling circuits except the water pump and the thermostat are configured on the cooling circuit on the side away from the stack of the water pump and the thermostat.

[0012] The present invention also provides a fuel cell stack cooling circuit that applies the fuel cell stack cooling circuit insulation treatment method as described above. The insulation treatment area is the cooled circuit portion of the insulation treatment, and the insulation treatment at least includes using insulating pipes for the corresponding pipe sections of the inlet pipe and the outlet pipe.

[0013] Preferably, the insulation treatment further includes using insulating joints and / or insulating gaskets.

[0014] Preferably, the cooling circuit portion within the pipeline length range that is a preset length threshold away from the position reference is specifically: the corresponding pipe section of the outlet pipe that is a first pipeline length away from the water outlet and the corresponding pipe section of the inlet pipe that is a second pipeline length away from the water inlet; and the first pipeline length L0 and the second pipeline length L8 satisfy the following condition:

[0015] In the formula, L0 is the first pipeline length, L8 is the second pipeline length, R min is the minimum value of the insulation resistance of the stack to the ground, σ is the conductivity of the stack coolant, and r0 is the pipe radius of the outlet pipe and the inlet pipe.

[0016] Preferably, the cooling circuit includes: a water pump disposed at a position on the inlet pipe that is at a distance of the first pipe length from the water inlet; a thermostat disposed at a position on the outlet pipe that is at a distance of the second pipe length from the water outlet; and other components of the cooling circuit other than the water pump and the thermostat are disposed on the side of the water pump and the thermostat away from the fuel cell stack.

[0017] Preferably, other components of the cooling circuit include: an intercooler, a heat exchanger, and a deionizer, which are connected in parallel between the inlet of the water pump and the first working interface of the thermostat; a main radiator and a secondary radiator, which are connected in parallel between the inlet of the water pump and the second working interface of the thermostat.

[0018] The present invention also provides an automobile, including a fuel cell stack, and further including the fuel cell stack cooling circuit as described above.

[0019] For the fuel cell stack, this solution innovatively proposes an insulation treatment solution for the cooling circuit. Specifically, taking the water inlet and the water outlet of the fuel cell stack as the position references respectively, and determining the part of the cooling circuit within the pipeline length range at a preset length threshold from the position reference as the insulation treatment area; that is to say, based on the fact that the coolant used in the fuel cell stack is deionized water and the conductivity can be effectively controlled, an effective convergence solution for the fuel cell stack cooling circuit is proposed. This solution divides the cooling circuit of the fuel cell stack, and only performs it on the local cooling circuit that has an obvious impact on the insulation resistance, such as but not limited to the corresponding pipe sections of the inlet pipe connected to the water inlet and the outlet pipe connected to the water outlet. The remaining part of the cooling circuit does not need to be subjected to secondary insulation treatment. Compared with the solution of performing secondary insulation treatment on the entire cooling circuit, this solution can effectively control the secondary insulation points, and on the basis of effectively reducing costs, can greatly improve the insulation reliability.

[0020] In the preferred solution of the present invention, the first pipe length L0 and the second pipe length L8 satisfy the following conditions: wherein, R min is the minimum value of the insulation resistance of the fuel cell stack to the ground. With such a setting, the length of the corresponding pipe section that needs secondary insulation treatment can be minimized to further reduce the material cost and the assembly cost; and the water pump of the cooling circuit is disposed at a position on the inlet pipe that is at a distance of the first pipe length L0 from the water inlet, and the thermostat of the cooling circuit is disposed at a position on the outlet pipe that is at a distance of the second pipe length L8 from the water outlet; the components of the other cooling circuits other than the water pump and the thermostat are disposed on the side of the water pump and the thermostat away from the fuel cell stack on the cooling circuit; with such a setting, the number of secondary insulation points can be minimized. Description of the Drawings

[0021] Figure 1Schematic diagram of the principle of the fuel cell stack cooling circuit described in the specific implementation mode;

[0022] Figure 2 is Figure 1 Schematic diagram of the equivalent resistance of the fuel cell stack cooling circuit shown in

[0023] In the figure:

[0024] Stack 1, water inlet 11, water outlet 12, water pump 2, thermostat 3, first working interface 31, second working interface 32, intercooler 4, heat exchanger 5, deionizer 6, main radiator 7, auxiliary radiator 8, expansion water tank 9. Specific implementation mode

[0025] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Without loss of generality, this embodiment takes Figure 1 the fuel cell stack cooling circuit of the fuel cell vehicle shown in

[0027] Please refer to Figure 1 , which is a schematic diagram of the principle of the fuel cell stack cooling circuit.

[0028] The fuel cell stack cooling circuit includes main components such as a water pump 2, a thermostat 3, an intercooler 4, a heat exchanger 5, a deionizer 6, a main radiator 7, an auxiliary radiator 8, and an expansion water tank 9, so as to start different levels of heat dissipation treatment according to the system operation state.

[0029] Based on the characteristics that the coolant used in the fuel cell stack is deionized water and the conductivity can be effectively controlled, the following insulation treatment method is adopted in this scheme to divide the insulation treatment area. Specifically, the water inlet 11 and the water outlet 12 of the stack 1 are used as the position references respectively, and the cooling circuit part within the pipeline length range with a preset length threshold from the position reference is determined as the insulation treatment area; that is, the cooling circuit part within this length range is used as the secondary insulation treatment area, while the cooling circuit part outside this length range does not need to be insulated.

[0030] Compared with the scheme of implementing secondary insulation treatment for the entire cooling circuit, this embodiment proposes a convergent scheme that can effectively reduce the number of secondary insulation points.

[0031] It is understandable that the cooling circuit part as the secondary insulation treatment area at least includes the corresponding pipe sections of the inlet pipe connected to the inlet 11 of the stack to establish the cooling circuit and the corresponding pipe sections of the outlet pipe connected to the outlet 12 of the stack. This solution can effectively control the secondary insulation points, and on the basis of effectively reducing costs, can greatly improve the insulation reliability.

[0032] The "preset length threshold" here refers to a preset value that meets the insulation requirements of the system operation. It should be noted that for different cooling circuits, this preset value should be determined according to the system parameters.

[0033] Combined with parameters such as the pipe diameter of the cooling circuit, the conductivity of the coolant, and the insulation resistance value that the vehicle requires the stack to reach, the following formula calculates the shortest distance required for secondary insulation treatment at the inlet and outlet of the stack.

[0034] The specific calculation is as follows in Formula 1:

[0035] The resistance calculation formula of the coolant body is: Among them, ρ is the resistivity, L is the pipe length, and S is the cross-sectional area of the pipe. The conductivity σ is the reciprocal of the resistivity ρ, that is, σ = 1 / ρ.

[0036] In order to further effectively reduce the number of secondary insulation points, the cooling circuit insulation treatment method provided by this solution can limit the insulation treatment area to the corresponding pipe sections of the outlet pipe and the inlet pipe.

[0037] Specifically, the cooling circuit part within the pipe length range with a preset length threshold from this position reference is: the corresponding pipe section of the outlet pipe with a distance of the first pipe length L0 from the outlet 12 and the corresponding pipe section of the inlet pipe with a distance of the second pipe length L8 from the inlet 11, where the first pipe length L0 and the second pipe length L8 meet the preset length threshold. That is, the first pipe length L0 and the second pipe length L8 are at least greater than the corresponding preset length threshold, that is, the technical effect of effectively reducing the number of secondary insulation points can be achieved.

[0038] Based on the above Formula 1, the Figure 1 cooling water pipe paths of each part of the stack cooling circuit shown in can be equivalent to resistors. Please refer to Figure 2 together. This figure is Figure 1 the equivalent resistance schematic diagram of the fuel cell stack cooling circuit shown in.

[0039] Assume that r0 is the pipe radius (inner diameter) of the water pipe from the stack to the water pump, and r8 is the pipe radius (inner diameter) of the water pipe from the stack to the thermostat. Substituting into Formula 1, the following Formula 2 can be obtained:

[0040]

[0041] Under normal circumstances, the pipe diameters of the inlet and outlet of the stack are equal, that is, r0 = r8, then On this basis, as described above, in order to limit the insulation treatment area to the corresponding pipe sections of the outlet pipe and the inlet pipe, the minimum value of R in the above formula should be taken, that is, the minimum value of the insulation resistance of the stack to the ground And the insulation grounding points are located at the water pump 2 and the thermostat 3. The first pipe length L0 and the second pipe length L8 meet the above formula, that is, meet the preset length threshold.

[0042] Assume that combined with the requirements of the vehicle insulation resistance value, the insulation resistance requirement for the stack system is greater than 2 MΩ, the pipe diameter of the inlet and outlet of the stack is 40 mm, and the conductivity is 5 μS / cm. That is, R min > 2 MΩ. Substituting the above values, we can get:

[0043] Furthermore, if the lengths of the two ends of the water pipes are equal, then L0 = L8 > 251.2 cm. Therefore, it is only necessary to ensure that the lengths of the corresponding pipe sections at both ends (the first pipe length L0 and the second pipe length L8) are both greater than 251.2 cm. For example, but not limited to Figure 1 As shown in the stack cooling circuit, the water pump 2 is arranged at a position on the inlet pipe that is the first pipe length L0 away from the water inlet 11, and the thermostat 3 is arranged at a position on the outlet pipe that is the second pipe length L8 away from the water outlet 12; other components of the cooling circuit except the water pump 2 and the thermostat 3 are arranged on the side of the circuit away from the stack 1 of the water pump 2 and the thermostat 3.

[0044] Preferably, the insulation treatment of this solution includes using insulating pipes for the corresponding pipe sections of the above-mentioned pipe lengths (the first pipe length L0 and the second pipe length L8) of the inlet pipe and the outlet pipe.

[0045] Of course, for the component characteristics of the circuit system, this insulation treatment includes, for example, but not limited to, using insulating joints and / or insulating pads and other treatment means. It can be understood that the specific implementation methods of the insulating pipe, insulating joint and insulating pad are not the core invention points of this application, and those skilled in the art can implement them based on the prior art, so they will not be elaborated herein.

[0046] In this solution, the inlet pipe and the outlet pipe are connected to the water inlet 11 and the water outlet 12 of the stack 1, thereby minimizing the material cost and assembly cost of the secondary insulation treatment. By ensuring good insulation of the corresponding pipe sections of the first pipe length L0 and the second pipe length L8 to the ground of the cooling circuit, the insulation state of the fuel cell vehicle can be effectively guaranteed. And the rest of the cooling circuit does not need to be subjected to secondary insulation treatment, and a lower-cost solution can be used for design and implementation.

[0047] In addition, except for the water pump 2 and the thermostat 3, the other components of the cooling circuit can be configured according to the actual circuit function requirements. As shown in the figure, the intercooler 4, the heat exchanger 5, and the deionizer 6 of this solution are arranged in parallel between the inlet of the water pump 2 and the first working interface 31 of the thermostat 3; the main radiator 7 and the auxiliary radiator 8 are arranged in parallel between the inlet of the water pump 2 and the second working interface 32 of the thermostat 3.

[0048] When the coolant temperature is low during the operation of the circuit, the thermostat 3 automatically closes the second working interface 32 leading to the main radiator 7 and the auxiliary radiator 8, and opens the first working interface 31 leading to the intercooler 4, the heat exchanger 5, and the deionizer 6. According to the processing needs, it enters the water pump 2 through the intercooler 4, the heat exchanger 5, and / or the deionizer 6, and is sent back to the fuel cell stack by the water pump 2 for recycling. This circulation route is equivalent to a small cycle.

[0049] When the coolant temperature is high during the operation of the circuit, the thermostat 3 automatically closes the first working interface 31 and opens the second working interface 32 leading to the main radiator 7 and the auxiliary radiator 8. The coolant flowing out of the fuel cell stack 1 is cooled by the radiator and then sent into the fuel cell stack 1 by the water pump 2, which improves the cooling intensity to prevent the fuel cell stack 1 from overheating. This circulation route is equivalent to a large cycle. Of course, according to the needs, the large and small cycles can also operate simultaneously, that is, part of the cooling water undergoes a large cycle, while the other part of the cooling water undergoes a small cycle.

[0050] In addition, the expansion water tank 9 in this solution is set at the interface position where the two branch circuits return, that is, between the heat exchanger 5 and the deionizer 6 shown in the figure.

[0051] In addition to the aforementioned fuel cell stack cooling circuit and its secondary insulation treatment method, this embodiment also provides a vehicle including a fuel cell stack, and also includes the fuel cell stack cooling circuit as described above. It should be understood that the other functional components of this vehicle are not the core inventive points of this application, and those skilled in the art can implement them based on the prior art, so they will not be elaborated herein.

[0052] It should be noted that in the actual application of the vehicle, there are certain control requirements for the conductivity of the fuel cell stack within a certain number of years and kilometers. The implementation path of the cooling circuit can be restricted by using the above calculation method in combination with the control requirements for conductivity.

[0053] It should be noted that in this embodiment, the configuration of the water pump 2 and the thermostat 3 is determined based on the corresponding pipe sections that meet the first pipe length L0 and the second pipe length L8, and the insulation area is divided. Of course, the division of this insulation area is not limited to the aforementioned preferred exemplary description, and can be specifically selected according to different circuit design requirements. As long as the core inventive concept of this application is applied, it is within the scope of protection requested by this application.

[0054] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for insulating treatment of a cooling circuit of a fuel cell stack, characterized in that, Taking the inlet and outlet of the stack as the position references respectively, and determining the insulation treatment area for the cooling circuit part within the pipeline length range that is at a preset length threshold away from the position reference; the cooling circuit part at least includes the corresponding pipe segments of the inlet pipe connected to the inlet and the outlet pipe connected to the outlet. The cooling circuit part within the pipeline length range that is at a preset length threshold away from the position reference is specifically: the corresponding pipe segment of the outlet pipe that is at a first pipeline length away from the outlet and the corresponding pipe segment of the inlet pipe that is at a second pipeline length away from the inlet, and the first pipeline length and the second pipeline length satisfy the following condition: Wherein, L0 is the length of the first pipeline, L8 is the length of the second pipeline, R min is the minimum value of the insulation resistance of the stack to the ground, σ is the conductivity of the coolant of the stack, and r0 is the pipe radius of the water outlet pipe and the water inlet pipe.

2. The method for insulating treatment of the cooling circuit of the fuel cell stack according to claim 1, wherein The water pump of the cooling circuit is arranged at the position of the inlet pipe that is at the first pipeline length away from the inlet, and the thermostat of the cooling circuit is arranged at the position of the outlet pipe that is at the second pipeline length away from the outlet; the other components of the cooling circuit except the water pump and the thermostat are arranged on the cooling circuit side away from the stack of the water pump and the thermostat.

3. Fuel cell stack cooling circuit, characterized in that, Applying the fuel cell stack cooling circuit insulation treatment method described in claim 1, the insulation treatment area is the insulated cooling circuit part, and the insulation treatment at least includes using insulated pipes for the corresponding pipe segments of the inlet pipe and the outlet pipe, and the inlet pipe and the outlet pipe are connected to the inlet and outlet of the stack.

4. The fuel cell stack cooling circuit according to claim 3, characterized in that, The insulation treatment further includes using insulated joints and / or insulated gaskets.

5. The fuel cell stack cooling circuit according to claim 3, characterized in that, The cooling circuit includes: A water pump, arranged at the position of the inlet pipe that is at the first pipeline length away from the inlet; A thermostat, arranged at the position of the outlet pipe that is at the second pipeline length away from the outlet; The other components of the cooling circuit except the water pump and the thermostat of the cooling circuit are all arranged on the side away from the stack of the water pump and the thermostat.

6. The fuel cell stack cooling circuit according to claim 5, characterized in that, The other components of the cooling circuit include: An intercooler, a heat exchanger and a deionizer, which are arranged in parallel between the inlet of the water pump and the first working interface of the thermostat; A main radiator and a secondary radiator, which are arranged in parallel between the inlet of the water pump and the second working interface of the thermostat.

7. An automobile, comprising a fuel cell stack, characterized in that, It further includes the fuel cell stack cooling circuit described in any one of claims 3-6.

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