COOLANT FLOW DISTRIBUTORS AND METHOD FOR THEIR USE

Abstract

Methods, devices, and vehicles for liquid cooling of a high-voltage device are provided. The devices comprise a body, a channel defining a coiled flow path through the body, the flow path being configured to accommodate a coolant flow through it, the channel walls being formed from a low-conductivity material exhibiting high electrical resistance in directions perpendicular to the coolant flow directions through the flow path, an inlet at a first end of the channel providing access to the flow path, and an outlet at a second end of the channel providing access to the flow path.

Description

INTRODUCTION

[0001] The technical field generally refers to the electrical insulation of coolants and, in particular, to a coolant flow distributor with a channel that defines a coiled flow path for a coolant.

[0002] Electric vehicles are subject to safety requirements that pose certain challenges for designers and engineers of vehicles with liquid-cooled fuel cell stacks. Although a certain degree of high impedance is permissible, liquid-cooled fuel cell stacks must be largely electrically isolated from the coolant circuit.

[0003] Electrical insulation of the coolant circuit can be achieved by using non-conductive or dielectric fluids. However, even traditionally non-conductive coolants (e.g., deionized water, oil) exhibit non-zero conductivity properties that can lead to leakage current through the coolant circuit.

[0004] Therefore, electrical insulation in coolant circuits is typically achieved through a combination of a low-conductivity fluid and a hose system configured to provide an elongated flow path to increase overall resistance, a process known as insulation resistance. However, these hose systems may be limited in their ability to increase electrical resistance. In particular, there may be insufficient hose length available due to limited space within the vehicle and / or the minimum bend radii of large-diameter hoses. Relatively small radii and changes in direction between hoses can be achieved using fittings; however, each additional fitting can introduce additional hydraulic losses.

[0005] Accordingly, there is a constant demand for systems and methods capable of promoting the electrical insulation of a coolant circuit in fuel cell stacks of electric vehicles. Furthermore, other desirable features and properties of the present disclosure will become apparent from the following detailed description and the attached claims in conjunction with the attached drawings and the preceding introduction. DESCRIPTION

[0006] A device for increasing the insulation resistance of a coolant is provided. In one example, the device comprises a body, a channel defining a coiled flow path through the body, the flow path being configured to accommodate a coolant flow through it, the walls of the channel being formed from a low-conductivity material exhibiting high electrical resistance in directions perpendicular to the directions of coolant flow through the flow path, an inlet at a first end of the channel providing access to the flow path, and an outlet at a second end of the channel providing access to the flow path.

[0007] In various examples, the body can be a single, integral structure.

[0008] In various examples, the body can consist entirely of a material with low conductivity.

[0009] In various examples, the channel can define the flow path in a helical shape.

[0010] In various examples, the channel can define the flow path in such a way that it has the shape of an Archimedean spiral.

[0011] In various examples, the device may include end connectors attached to or beside the inlet and outlet and configured to connect the inlet and outlet to other components of a liquid cooling system, so that the flow path defined by the channel is in fluid communication with a coolant circuit of the liquid cooling system, the liquid cooling system being exposed to a high voltage source.

[0012] In various examples, the device may include body connectors configured to attach the body to a structural component in a fixed position relative to it.

[0013] In various examples, the channel can have a bending radius of the centerline relative to the pipe's inner diameter of 1.5 or more.

[0014] A method for increasing the insulation resistance of a coolant is provided.In one example, the method comprises directing a stream of liquid coolant to cooling channels connected to a high-voltage device to dissipate heat generated during its operation, directing the stream of liquid coolant from the high-voltage device to an inlet of a coolant flow manifold, directing the stream of liquid coolant through a channel of the coolant flow manifold in fluid communication with the inlet, the channel defining a convoluted flow path configured to increase the length of the flow path and therefore increase the insulation resistance of the liquid coolant, and directing the liquid coolant from an outlet of the coolant flow manifold in fluid communication with the channel to a heat exchanger configured to reduce the temperature of the liquid coolant.

[0015] In various examples, the coolant flow distributor can be a one-piece, integrated structure made entirely of a low-conductivity material.

[0016] In various examples, the channel can define the flow path in a helical shape.

[0017] In various examples, the channel can define the flow path in such a way that it has the shape of an Archimedean spiral.

[0018] In various examples, the procedure may involve connecting the inlet and outlet to other components of a liquid cooling system by means of end connectors attached to or next to the inlet and outlet, so that the flow path defined by the channel is in fluid communication with a coolant circuit of the liquid cooling system.

[0019] In various examples, the method can include attaching the coolant flow distributor to a component in a fixed position relative to it, with body connections attached to the coolant flow distributor.

[0020] In various examples, the channel can have a bending radius of the centerline relative to the pipe's inner diameter of 1.5 or more.

[0021] A vehicle is provided to supply liquid cooling for a high-voltage device. In one example, the system comprises the high-voltage device, which generates heat during its operation; a liquid cooling system configured to circulate a coolant through a coolant loop in thermal contact with the high-voltage device, the liquid cooling system being configured to carry heat away from the high-voltage device with the coolant; a heat exchanger in thermal contact with the coolant loop and configured to reduce the temperature of the coolant; and a coolant flow distributor in fluid communication with the coolant loop.The coolant flow distributor comprises a body, a channel defining a coiled flow path through the body, the flow path being configured to accommodate the flow of the coolant, the walls of the channel being formed from a low-conductivity material exhibiting high electrical resistance in directions perpendicular to the directions of coolant flow through the flow path, an inlet at a first end of the channel providing access to the flow path, and an outlet at a second end of the channel providing access to the flow path.

[0022] In various examples, the body of the coolant flow distributor can be a one-piece, integral structure made entirely of the low-conductivity material.

[0023] In various examples, the channel of the coolant flow distributor can define the flow path in a helical shape or in the form of an Archimedean spiral.

[0024] In various examples, the channel can have a bending radius of the centerline relative to the pipe's inner diameter of 1.5 or more.

[0025] In various examples, the high-voltage device can be a fuel cell system. BRIEF DESCRIPTION OF THE FIGURES

[0026] The exemplary embodiments are described below in conjunction with the following figures, where the same numbers denote the same elements: Fig. Figure 1 is a functional block diagram showing an exemplary vehicle that includes a liquid cooling system with a coolant flow distributor according to certain aspects of an example; Fig. Figure 2 is a perspective view showing a first example of the coolant flow distributor of Fig. 1 represents in accordance with certain aspects of an example; Fig. Figure 3 is a perspective view showing a second example of the coolant flow distributor from Fig. 1 represents in accordance with certain aspects of an example; and Fig. Figure 4 is a flowchart showing an exemplary procedure for operating a liquid cooling system in accordance with certain aspects of an example. DETAILED DESCRIPTION

[0027] The following detailed description is merely exemplary and is not intended to limit application and use. Furthermore, there is no intention to be bound by any express or implied theory presented in the preceding introduction or the following detailed description.

[0028] Fig. Figure 1 shows an example vehicle 10. In certain examples, vehicle 10 is an automobile. In various examples, vehicle 10 can be any type of automobile, such as a sedan, station wagon, truck, or sport utility vehicle (SUV), and it can have two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD), and / or various other types of vehicles or mobile platforms in certain examples. In certain examples, vehicle 10 can be a bus, an airplane, a boat, a train, or an industrial vehicle.

[0029] As in Fig. As shown in Figure 1, the example vehicle 10 generally comprises a chassis 12, a body 14, front wheels 16, and rear wheels 18. The body 14 is mounted on the chassis 12 and essentially encloses components of the vehicle 10. The body 14 and the chassis 12 can together form a frame. The wheels 16 and 18 are each rotatably connected to the chassis 12 near a corner of the body 14.

[0030] The vehicle 10 also includes a drive system 20 and a fuel cell system. The drive system 20 includes an electric motor (e.g., a 3-phase AC motor) and can be connected to the vehicle wheels either directly or via a series of gears and differentials.

[0031] The fuel cell system is configured to generate electricity to power the electric motor of the drive system 20. In this example, the fuel cell system comprises a first fuel cell 24, a second fuel cell 26, a hydrogen storage unit 30, and a liquid cooling system 32. However, the fuel cell system can also contain fewer or more fuel cells. The fuel cell system generates electricity through an electrochemical reaction between hydrogen and oxygen. In short, in each of the fuel cells 24, 26, hydrogen molecules (H2) enter an anode, where they are split into protons and electrons. The protons migrate through an electrolyte membrane to a cathode, while the electrons travel through an external circuit, generating electricity. The oxygen (e.g.,The hydrogen (from the air) is supplied to the cathode side of the fuel cells 24, 26, where it combines with the protons and electrons that have come from the anode side, forming water (H2O) as a byproduct. Although not shown, the vehicle 10 may contain one or more batteries (e.g., lithium-ion battery packs) configured to store excess electricity generated by the fuel cell system.

[0032] The liquid cooling system 32 is configured to circulate a coolant through a coolant circuit comprising a network of channels or passages in or adjacent to the fuel cells 24, 26, and to dissipate heat from it. The liquid cooling system 32 may include a pump configured to circulate the coolant through the coolant circuit, as well as a heat exchanger configured to extract heat from the coolant. The heat exchanger may include passages or channels that are part of the coolant circuit, or it may be separate from it but in thermal contact with the coolant circuit. Various coolants can be used in the liquid cooling system 32, including, but not limited to, various low-conductivity coolants. In some examples, the coolant may be a water-based solution with additives, e.g.,a mixture of water and antifreeze (such as ethylene glycol or propylene glycol).

[0033] The liquid cooling system 32 can comprise various components configured such that the coolant is electrically isolated from the fuel cells 24 and 26. In this example, the liquid cooling system 32 comprises at least one coolant flow distributor 28, which includes at least one channel forming part of the coolant circuit and is configured to provide a flow path for the coolant. In this non-restrictive example, the coolant flow distributor 28 provides a flow path from the first fuel cell 24 to the second fuel cell 26; however, the coolant flow distributor 28 can also be located at other points in the coolant circuit, for example, upstream of the first fuel cell 24 or downstream of the second fuel cell 26.The coolant flow distributor 28 can comprise an integral body formed from or containing one or more non-conductive materials, such as various non-conductive polymers and ceramics, to provide high electrical resistance perpendicular to the direction of coolant flow. The coolant flow distributor 28 can be manufactured using various manufacturing processes. In some examples, the coolant flow distributor 28 can be manufactured by casting, injection molding, or additive manufacturing processes.

[0034] The flow path provided by the coolant flow distributor 28 can be elongated to electrically insulate the coolant via an insulation resistance. The electrolytic resistance is directly proportional to the length of the conductive fluid flow path and inversely proportional to the cross-sectional diameter of the fluid flow path. Therefore, to reduce the electrical current losses through a fluid, the length of the fluid path can be increased—given constant material properties of the fluid—to increase the total resistance, which is referred to as the insulation resistance and is represented in Equation 1. R=ρLA where R is the resistance, ρ is the specific resistance of the coolant, L is the length of the coolant flow path and A is the cross-sectional area of ​​the coolant flow path.

[0035] In this example, the coolant flow distributor 28 provides a flow path that is coiled to increase its overall length within a predetermined range, thereby promoting improved coolant resistance within the coolant circuit. In various other applications, the coolant flow distributor 28 can provide a channel that defines a flow path within a fixed volume that is longer than would otherwise be possible with a hose of comparable diameter and insulation properties. For example, large-diameter hoses can have relatively large bending radii due to their limited flexibility. Therefore, existing hose systems typically use connectors between the hoses to achieve small bending radii. However, these connectors can increase hydraulic losses within the hose systems.In contrast, the coolant flow distributor 28, due to its integral body structure, allows for relatively small bending radii compared to the large diameter of the flow path. For example, the body of the coolant flow distributor 28 can have common walls between adjacent sections of the channel, eliminating or reducing the packing clearance required for a given length of flow path. Furthermore, the absence of connecting pieces along the flow path avoids the hydraulic losses typically associated with such pieces.

[0036] The channel within the coolant flow distributor 28 can define various flow paths. For simplicity, the radii of the bends within the channel are referred to as the major radius(s), and the inner radius of the channel as the minor radius. In general, the shape and size of the flow path can be determined by balancing competing factors, including maximizing the length within a limited volume (i.e., saving space) and minimizing hydraulic loss. In particular, reducing the major radii allows for a greater overall flow path length within a fixed volume. However, reducing the major radii also increases hydraulic losses in the flow path, requiring higher pressures to move the coolant through it. The specific major and minor radii of the channel can be determined according to the requirements of the particular application.

[0037] Fig. Figure 2 shows a first example of a coolant flow distributor 128, which can be used as the coolant flow distributor 28 of the vehicle 10. In this example, the coolant flow distributor 128 comprises a one-piece body 130 with a channel 136 located therein, defining a helical flow path. The coolant flow distributor 128 can therefore be particularly advantageous for cylindrical or cuboid packing volumes. The body 130 includes a first inlet / outlet 132 at a first end of the channel 136 and a second inlet / outlet 134 at a second end of the channel 136. The length, the major radius(s), and the minor radius of the channel 136 can be adjusted to achieve a specific degree of insulation resistance. In this example, the channel 136 has a uniform curvature with a uniform major radius over the entire flow path.Alternatively, channel 136 can have a non-uniform curvature with more than one principal radius.

[0038] The coolant flow distributor 128 can include connections that are integrated with or attached to the body 130 to connect and secure the coolant flow distributor 128 within the liquid cooling system 32. For example, end connectors 138 can be located next to the first and second inlet / outlet 132, 134, configured to attach the coolant flow distributor 128 to other components of the coolant circuit, such as other hoses or the fuel cells 24, 26. Body connectors 140 can be located on the outer surfaces of the body 130 to secure the body 130 in a fixed position within the vehicle 10, e.g., to the frame.The end connectors 138 and the body connectors 140 can be various types of connectors, including but not limited to hose clamps, barbed connectors, quick-release connectors, threaded connectors, flange connectors, flanges with holes or slots for receiving fasteners, hose clamps, etc.

[0039] Fig. Figure 3 presents a second exemplary coolant flow distributor 228, which can be used as the coolant flow distributor 28 of the vehicle 10. In this example, the coolant flow distributor 228 comprises a one-piece body 230 with a channel 236 located therein, defining an Archimedean spiral flow path. As such, the coolant flow distributor 228 can be particularly advantageous for relatively shallow packaging volumes. The body 230 includes a first inlet / outlet 232 at a first end of the channel 236 and a second inlet / outlet 234 at a second end of the channel 236. The length, larger radii, and smaller radii of the channel 136 can be adjusted to achieve a specific degree of insulation resistance. In this example, the channel 136 has a non-uniform curvature with larger radii that decrease as the flow path approaches the center of the body 230.Therefore, the main radius at or near the second inlet / outlet 234 can be considered the minimum main radius of the channel 236.

[0040] As in the previous example in Fig. 2 The coolant flow distributor 228 can include connections that are integrated with or attached to the body 230 to couple and secure the coolant flow distributor 228 within the liquid cooling system 32. For example, end connectors 238 can be located next to the first and second inlet / outlet 232, 234, configured to attach the coolant flow distributor 228 to other components of the coolant circuit, such as other hoses or the fuel cells 24, 26. Body connectors 240 can be located on the outer surfaces of the body 230 to secure the body 230 in a fixed position within the vehicle 10, e.g., to its frame.The end connectors 238 and the body connectors 240 can be various types of connectors, including but not limited to hose clamps, barbed fittings, quick-release fittings, threaded fittings, flange fittings, flanges with holes or slots for receiving fasteners, hose clamps, etc.

[0041] In various examples, the coolant flow distributors 28, 128, 228 can have a larger radius or an average larger radius (or alternatively, a center bend radius) that is greater than or equal to the inner diameter of the channel 236, with the hydraulic losses being proportional to the center bend radius divided by the inner diameter. It has been found that the hydraulic loss factors are greatest near a ratio of 1.0 between the center bend radius and the inner diameter of the pipe, with significant improvements at ratios of approximately 1.5 to 2.0, and the loss reduction decreasing further at ratios between 2.0 and 6.0. Therefore, the coolant flow distributors 28, 128, 228 can have a center bend radius to pipe inner diameter ratio of 1.5 or greater, such as 1.5–2.0.

[0042] It goes without saying that the examples in the Fig. 2 and Fig. 3 are merely examples and the coolant flow distributor 28 may have other structures, including channels that define flow paths with different shapes and / or patterns with different major and minor radii. In contrast to the examples in the Fig. 2 and Fig. 3. The coolant flow distributor 28 can also have external surfaces that do not correspond to the shape of the channel contained therein. For example, the coolant flow distributor 28 can have one or more external surfaces that are essentially flat. As a specific example, the coolant flow distributor 28 can have an external shape that essentially defines a cuboid.

[0043] Although in the Fig. While the coolant flow distributors 128, 228 are shown separately from other components of the liquid cooling system 32 and the fuel cells 24, 26 in Figures 1-3, the coolant flow distributor 28 can instead be an integral part or an assembled component of the liquid cooling system 32 and / or the fuel cells 24, 26. For example, the coolant flow distributor 28 can be an integral part of a component of the first fuel cell 24 and / or the second fuel cell 26, such as a component that has cooling channels within one or both fuel cells 24, 26.

[0044] With reference to Fig. 4 and with continued reference to the Fig. Figures 1 to 3 show a flowchart of a method 300 for operating a liquid cooling system, such as the liquid cooling system 32 of vehicle 10, in accordance with various examples. As can be seen from the disclosure, the sequence of method 300 is not limited to the one shown in Fig. The sequential execution shown in section 4 is limited, but can be carried out in one or more different sequences depending on applicability and in accordance with the present disclosure.

[0045] In one example, the method 300 may begin at 310. At 312, the method 300 may include directing a flow of liquid coolant to cooling channels connected to a high-voltage device to dissipate the heat generated during operation. In some examples, the high-voltage device may include one or more fuel cells. At 314, the method 300 may include directing the flow of liquid coolant from the high-voltage device to an inlet of a coolant flow distributor. At 316, the method 300 may include directing the flow of liquid coolant through a channel of the coolant flow distributor in fluid communication with the inlet, the channel defining a convoluted flow path configured to increase the length of the flow path and therefore increase the insulation resistance of the liquid coolant.In 318, method 300 may involve directing the liquid coolant from an outlet of the coolant flow distributor, which is in fluid communication with the channel, to a heat exchanger configured to reduce the temperature of the liquid coolant. In some examples, the cooling channels associated with the high-voltage device, the channel of the coolant flow distributor, and / or the heat exchanger may be part of a coolant circuit of a liquid cooling system. In such examples, the liquid coolant may be circulated through the coolant circuit by a pump. Method 300 may terminate at 320.

[0046] Although the coolant flow distributors 28, 128, 228 are discussed here in relation to vehicle 10 and its fuel cell system, the coolant flow distributors are not limited to vehicles or fuel cell systems. Rather, the coolant flow distributors can be used for various liquid-cooled high-voltage devices, where a coolant is electrically isolated from a high-voltage source.

[0047] The systems and methods disclosed here offer several advantages over certain existing systems and methods. For example, the integrated body of the coolant flow distributors described here can enable flow paths with smaller bending radii (major radii) compared to certain existing hose systems, while simultaneously avoiding hydraulic losses associated with hose connections. As such, the coolant flow distributors can offer improved insulation resistance for the coolant in a compact form factor.

[0048] Although at least one exemplary embodiment has been presented in the preceding detailed description, it should be understood that there are numerous variations. It should also be noted that the exemplary embodiment or embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the preceding detailed description is intended to provide the person skilled in the art with a practical guide for implementing the exemplary embodiment or embodiments. It is understood that various modifications to the function and arrangement of the elements can be made without departing from the scope of the disclosure as set forth in the appended claims and their statutory equivalents.

Images