Steering wheel assembly for a vehicle and vehicle

Abstract

This application discloses a steering wheel assembly for a vehicle and a vehicle having the same. The steering wheel assembly includes: a steering wheel frame; a first foam layer covering the outside of the steering wheel frame; a second foam layer covering the outside of the first foam layer and serving as the outermost layer for direct contact with a human hand; the second foam layer is composed of or doped with a weakly conductive material to give it overall weakly conductive properties; the second foam layer is used to couple with the human hand to form a capacitor; and a detection device adapted to detect changes in capacitance caused by a human hand approaching or contacting the second foam layer. The steering wheel assembly for a vehicle designed according to this application incorporates a second foam layer with weakly conductive properties that directly contacts the human hand, thereby shortening the sensing distance while increasing the effective sensing area, thus improving the sensitivity and signal stability of off-hand detection.

Description

Cross-references to related applications

[0001] This application claims priority to Chinese patent application No. 202620417427.X, filed on March 31, 2026, entitled "Steering wheel assembly for a vehicle and vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of vehicles, and in particular to a steering wheel assembly for a vehicle and a vehicle. Background Technology

[0003] In related technologies, Hands-On Detection (HOD) is a function in vehicle intelligent driving assistance systems, used to detect in real time whether the driver's hands have left the steering wheel. Capacitive sensing HOD is based on the principle of capacitive sensing and has advantages such as fast response speed. In the principle of capacitive sensing, the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d.

[0004] In the structure of a steering wheel using capacitive sensing HOD, the components typically consist of, from the inside out, a steering wheel frame, a primary foam layer, a capacitive sensing layer, a secondary foam layer, and a leather layer. The capacitive sensing layer is usually used to detect the hand contact status, while the leather layer serves as the surface that the hand directly contacts. Because there is a relatively thick secondary foam layer between the capacitive sensing layer and the hand, i.e., a large sensing distance d, the capacitive sensing sensitivity of this type of steering wheel with capacitive sensing HOD is low. This makes it difficult for the vehicle to obtain the driver's hands-off signal in a timely manner, posing a safety hazard.

[0005] To improve capacitive sensing sensitivity, some existing technologies design the leather layer as a weakly conductive layer. However, using a weakly conductive material for the leather layer can affect the surface feel and performance of the leather. Furthermore, the connection between the leather layer and the secondary foaming layer may be weakened due to material modification, resulting in a poor user experience. Summary of the Invention

[0006] This application aims to address at least one of the technical problems existing in the prior art. To this end, one objective of this application is to provide a steering wheel assembly for vehicles. The steering wheel assembly for vehicles designed according to this application incorporates a second foam layer with weakly conductive properties that comes into direct contact with the human hand, thereby shortening the sensing distance while increasing the effective sensing area, thus improving the sensitivity and signal stability of off-hand detection.

[0007] This application also proposes a vehicle having the aforementioned steering wheel assembly for a vehicle.

[0008] The steering wheel assembly for a vehicle according to this application includes: a steering wheel frame; a first foam layer covering the outside of the steering wheel frame; a second foam layer covering the outside of the first foam layer and serving as the outermost layer for direct contact with a human hand, the second foam layer being composed of or doped with a weakly conductive material to give it overall weakly conductive properties, the second foam layer being used to couple with a human hand to form a capacitor; and a detection device adapted to detect changes in capacitance caused by a human hand approaching or contacting the second foam layer.

[0009] According to the steering wheel assembly for vehicles of this application, by designing the second foam layer to have weak conductivity and to be in direct contact with the human hand, the sensing distance is shortened. Since the entire second foam layer also serves as part of the sensing electrode, the effective sensing area is increased. As the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d in the principle of capacitive sensing, the steering wheel assembly designed according to this application, due to the shortened sensing distance and increased effective sensing area, allows the hands-off detection system to obtain a larger capacitance change, thereby improving the sensitivity and signal stability of hands-off detection. Furthermore, the hands-off detection system has high judgment accuracy, a good user experience, and enhances vehicle safety and intelligence.

[0010] According to some embodiments of this application, the surface sheet resistance of the second foaming layer is 10. 3 ~10 6 Ω.

[0011] According to some embodiments of this application, the second foaming layer is a polyurethane foaming layer doped with a weakly conductive material.

[0012] According to some embodiments of this application, the weakly conductive material comprises at least one of carbon black, carbon nanotubes, conductive fibers, and conductive powder.

[0013] According to some embodiments of this application, the detection device is electrically connected to the second foaming layer.

[0014] According to some embodiments of this application, the detection device is mounted on the steering wheel frame; a conductor is embedded inside the second foam layer, the conductor extending along the contour of the steering wheel frame and electrically connected to the detection device.

[0015] According to some embodiments of this application, the steering wheel assembly for a vehicle further includes: a capacitive sensing layer disposed between the first foam layer and the second foam layer, and having conductive properties; wherein the detection device is electrically connected to the second foam layer and / or the capacitive sensing layer.

[0016] According to some embodiments of this application, in the thickness direction of the second foamed layer, the concentration of the weakly conductive material on the side closer to the human hand is higher than the concentration on the side closer to the capacitive sensing layer.

[0017] According to some embodiments of this application, the first foam layer is a polyurethane foam layer that is foamed and molded on the steering wheel frame in one step.

[0018] The vehicle according to another embodiment of this application is briefly described below.

[0019] The vehicle according to this application includes the steering wheel assembly for a vehicle described in any of the above embodiments. Since the vehicle according to this application is equipped with the steering wheel assembly for a vehicle described in the above embodiments, the vehicle has better safety performance.

[0020] In summary, the steering wheel assembly for vehicles according to this application shortens the sensing distance by designing the second foam layer to have weak conductivity and direct contact with the human hand. Since the entire second foam layer also serves as part of the sensing electrode, the effective sensing area is increased. Because the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d in the capacitive sensing principle, the steering wheel assembly designed according to this application, with its shortened sensing distance and increased effective sensing area, allows the hands-off detection system to obtain a larger capacitance change, thereby improving the sensitivity and signal stability of hands-off detection. Furthermore, the hands-off detection system has high judgment accuracy, a good user experience, and enhances vehicle safety and intelligence.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a steering wheel assembly structure according to some embodiments of this application.

[0023] Figure 2 According to the first embodiment of this application Figure 1 Enlarged view of point A in the middle.

[0024] Figure 3 This is a schematic diagram of a steering wheel assembly structure according to other embodiments of this application.

[0025] Figure 4 This is a schematic diagram of a steering wheel assembly structure according to some embodiments of this application.

[0026] Figure 5 yes Figure 3 and Figure 4 A schematic diagram of the capacitance monitoring principle in the embodiment.

[0027] Figure 6 According to the second embodiment of this application Figure 1 Enlarged view of point A in the middle.

[0028] Figure 7 yes Figure 6 A schematic diagram of the capacitance monitoring principle in an embodiment.

[0029] Figure 8 This is a schematic diagram of the application principle of a steering wheel assembly according to some embodiments of this application.

[0030] Figure 9 This is a schematic diagram of the application of a steering wheel assembly according to other embodiments of this application.

[0031] Figure 10 This is a schematic diagram of the detection device according to an embodiment of this application.

[0032] Figure 11 This is a schematic diagram of a hands-free monitoring system according to an embodiment of this application.

[0033] Figure label: 1. Steering wheel assembly; 10. Steering wheel frame; 11. Ring frame; 12. Support frame; 20. First foam layer; 30. Capacitive sensing layer; 40. Second foam layer; 50. Conductor; 60. Detection device; 2. Hand. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] In related technologies, Hands-On Detection (HOD) is a function in vehicle intelligent driving assistance systems, used to detect in real time whether the driver's hands have left the steering wheel. Capacitive sensing HOD is based on the principle of capacitive sensing and has advantages such as fast response speed. In the principle of capacitive sensing, the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d.

[0040] In the structure of a steering wheel using capacitive sensing HOD, the components typically consist of, from the inside out, a steering wheel frame, a primary foam layer, a capacitive sensing layer, a secondary foam layer, and a leather layer. The capacitive sensing layer is usually used to detect the hand contact status, while the leather layer serves as the surface that the hand directly contacts. Because there is a relatively thick secondary foam layer between the capacitive sensing layer and the hand, i.e., a large sensing distance d, the capacitive sensing sensitivity of this type of steering wheel with capacitive sensing HOD is low. This makes it difficult for the vehicle to obtain the driver's hands-off signal in a timely manner, posing a safety hazard.

[0041] To improve capacitive sensing sensitivity, some existing technologies design the leather layer as a weakly conductive layer. However, using a weakly conductive material for the leather layer can affect the surface feel and performance of the leather. Furthermore, the connection between the leather layer and the secondary foaming layer may be weakened due to material modification, resulting in a poor user experience.

[0042] The following is for reference. Figures 1-11 A steering wheel assembly 1 for a vehicle according to an embodiment of this application is described.

[0043] like Figures 1-7 As shown, the steering wheel assembly 1 for a vehicle according to this application includes: a steering wheel frame 10, a first foam layer 20, a second foam layer 40, and a detection device 60. The first foam layer 20 covers the outside of the steering wheel frame 10; the second foam layer 40 covers the outside of the first foam layer 20 and serves as the outermost layer for direct contact with a human hand 2. The second foam layer 40 is made of or doped with a weakly conductive material to give it overall weakly conductive properties. The second foam layer 40 is used to couple with the human hand 2 to form a capacitor; the detection device 60 is adapted to detect the capacitance change caused by the human hand 2 approaching or contacting the second foam layer 40.

[0044] Specifically, the steering wheel assembly 1 is used in a vehicle and includes a steering wheel frame 10, a first foam layer 20, a second foam layer 40, and a detection device 60. The steering wheel frame 10 is the internal support structure of the steering wheel, generally made of metal, and serves as the load-bearing frame of the steering wheel. The steering wheel assembly 1 designed according to this application uses a capacitive sensing HOD, which is based on the principle of capacitive sensing, where the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d.

[0045] Here, the first foam layer 20 covers the outside of the steering wheel frame 10 and is made of insulating material. The first foam layer 20 generally has no conductivity or very low conductivity to ensure the stability of the capacitance detection signal. The second foam layer 40 covers the outside of the first foam layer 20 and serves as the outermost layer of the steering wheel, directly contacting the driver's hand 2. The second foam layer 40 is made of a weakly conductive material, or a weakly conductive material is doped into its matrix material, thus giving the second foam layer 40 overall weak conductivity. When the driver's hand contacts the steering wheel assembly 1, the hand 2 directly contacts the outer surface of the second foam layer 40. Due to the overall weak conductivity of the second foam layer 40, capacitive coupling is formed between the hand 2 and the second foam layer 40, and the entire second foam layer 40 is equivalent to part of the sensing electrode. At this time, the sensing distance between the hand 2 and the second foam layer 40 is shortened to approximately zero, thereby obtaining a larger capacitance change. The detection device 60 is used to collect the capacitance value of the second foam layer 40 in real time and determine the hand contact state based on the change in capacitance value. The second foam layer 40 and the detection device 60 together form the hand-off monitoring system of the steering wheel assembly 1. When the hand 2 touches the second foam layer 40, the detection device 60 detects an increase in capacitance value. When the hand 2 leaves, the capacitance value returns to the reference value.

[0046] According to the steering wheel assembly 1 for vehicles of this application, by designing the second foam layer 40 to have weak conductivity and to be in direct contact with the human hand 2, the sensing distance is shortened. Since the entire second foam layer 40 also serves as part of the sensing electrode, the effective sensing area is increased. As the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d in the principle of capacitive sensing, the steering wheel assembly 1 designed according to this application, due to the shortened sensing distance and increased effective sensing area, allows the hands-off monitoring system to obtain a larger capacitance change, thereby improving the sensitivity and signal stability of hands-off monitoring. Furthermore, the hands-off monitoring system has high judgment accuracy, a good user experience, and enhances vehicle safety and intelligence.

[0047] According to some embodiments of this application, the surface sheet resistance of the second foaming layer 40 is 10. 3 ~10 6 Ω. Specifically, when the surface sheet resistance of the second foam layer 40 is less than 10 Ω. 3 When the resistance is Ω, its conductivity is too strong, which may lead to capacitance signal saturation, making it difficult for the detection device 60 to distinguish signal differences under different gripping states. Furthermore, excessive addition of weakly conductive material will reduce the flowability of the foaming material, affecting the foaming quality and potentially causing problems such as uneven density, surface porosity, or cracking in the second foam layer 40. When the surface sheet resistance of the second foam layer 40 is higher than 10... 6When the surface resistance is Ω, its weak conductivity is not obvious, the capacitive coupling effect between the hand 2 and the second foam layer 40 is weak, and the improvement effect on the sensitivity of off-hand detection is limited. By limiting the surface sheet resistance of the second foam layer 40 to 10Ω... 3 ~10 6 Between Ω, better capacitive coupling effect can be achieved while ensuring the mechanical properties and molding quality of the second foam layer 40, thereby improving the sensitivity and signal stability of the off-hand monitoring system.

[0048] According to some embodiments of this application, the second foaming layer 40 is a polyurethane foaming layer doped with a weakly conductive material. Specifically, polyurethane foam is the mainstream molding material for steering wheel foam layers, possessing advantages such as mature technology, good flowability, excellent resilience, and comfortable feel. In the steering wheel assembly 1 designed according to this application, based on the existing polyurethane foaming process, carbon black, carbon nanotubes, conductive fibers, or conductive powder can be selected as weakly conductive materials and mixed into the polyurethane foaming raw materials in a certain proportion. By doping the polyurethane foaming raw materials with weakly conductive materials, the originally insulating polyurethane foam body acquires certain weakly conductive properties. Furthermore, the weakly conductive materials can be selected as a single filler or a combination scheme according to color and cost requirements. For example, carbon nanotubes can be used for light-colored steering wheels, and carbon black can be used for dark-colored steering wheels, to balance appearance and performance. This design of the second foaming layer 40 allows the steering wheel assembly 1 to be achieved without changing the existing steering wheel production process, simply by optimizing the foaming material formula of the second foaming layer 40, without adding production steps. It has low cost, low production process difficulty, high yield, and good process compatibility.

[0049] During the preparation process, the weakly conductive material can be dispersed in the polyurethane foam raw material components, and the stirring speed should be controlled at 1000-3000 rpm, the dispersion time at 10-30 min, and the dispersion temperature at 20-40℃. This ensures that the weakly conductive material is uniformly dispersed in the polyurethane foam raw material components, avoiding problems such as uneven mixing and density caused by directly adding the weakly conductive material. The foaming process parameters, such as the ratio of A and B materials, mold temperature, injection pressure, curing time, and holding time, can be finely adjusted and optimized according to the actual product quality to ensure that there are no defects such as foam collapse, surface pores, or cracks.

[0050] Here, the weakly conductive material includes at least one of carbon black, carbon nanotubes, conductive fibers, and conductive powder. In other words, the weakly conductive material incorporated into the polyurethane foam raw material can include at least one of carbon black, carbon nanotubes, conductive fibers, and conductive powder. Micro-conductivity is achieved by mixing in a certain proportion of carbon black, carbon nanotubes, conductive fibers, or conductive powder, giving the originally insulating polyurethane foam a certain degree of weak conductivity. This allows for the weakly conductive modification of the second foam layer 40 with lower process modification and material costs, while fully utilizing the advantages of existing polyurethane foaming processes, thus providing a capacitive coupling medium for the off-hand monitoring system.

[0051] According to some embodiments of this application, such as Figures 3-5 As shown, the detection device 60 is electrically connected to the second foam layer 40. Specifically, the detection device 60 can be installed on the steering wheel frame 10 or inside the steering wheel assembly 1. The detection device 60 and the second foam layer 40 form an electrical path. During the detection process, the detection device 60 collects the capacitance value of the second foam layer 40 in real time. Since the second foam layer 40 has weak conductivity and is in direct contact with the hand 2, capacitive coupling can be formed between the hand 2 and the second foam layer 40. This capacitance change is directly transmitted to the detection device 60 through the electrical connection. The capacitance detection circuit inside the detection device 60 collects the capacitance signal and determines the hand contact state based on the change in capacitance value, outputting the hand-off monitoring result. By electrically connecting the detection device 60 to the second foam layer 40, efficient signal transmission can be achieved without intermediate signal conversion, thereby improving detection sensitivity, increasing the reliability of the hand-off monitoring system, and simplifying the structure of the hand-off monitoring system.

[0052] According to some embodiments of this application, such as Figures 3-5 As shown, the detection device 60 is mounted on the steering wheel frame 10; a conductor 50 is embedded inside the second foam layer 40, extending along the contour of the steering wheel frame 10 and electrically connected to the detection device 60. In some embodiments, the steering wheel frame 10 includes an annular frame 11 and a support frame 12. The annular frame 11 is covered with a first foam layer 20, and the support frame 12 is located radially inside the annular frame 11, connected to the annular frame 11, and used for connection to the vehicle body. The detection device 60 can be directly mounted on the annular frame 11 or the support frame 12 to utilize the inherent space of the steering wheel for installation. A conductor 50 is embedded inside the second foam layer 40. One end of the conductor 50 is electrically in contact with the second foam layer 40, and the other end is electrically connected to the input terminal of the detection device 60 to form a complete signal transmission path. The conductor 50 can be one or more of wires, conductive ink, conductive film or conductive mesh, and it extends along the contour of the annular skeleton 11 or the support skeleton 12 to ensure reliable contact between itself and each area of ​​the second foam layer 40.

[0053] During the molding process of the second foam layer 40, the conductor 50 can be pre-placed in the corresponding position within the mold, followed by the injection of foaming material. After foaming and molding, the conductor 50 is embedded inside the second foam layer 40, forming a tight, integrated structure with it. No additional fixing or bonding is required, resulting in a simple process and reliable connection. In some specific embodiments, the conductor 50 is a copper wire. The portion of the copper wire sheath stripped during the molding process of the second foam layer 40 can be completely wrapped to achieve electrical connection. A stripped wire sheath length of approximately 100mm is sufficient. The copper wire is then electrically connected using a hard connection process (terminal crimping or rivet) to achieve the off-hand detection function.

[0054] exist Figure 5 In the illustrated embodiment, the steering wheel assembly 1 includes a steering wheel frame 10, a first foam layer 20, and a second foam layer 40. The capacitance Cdb between the second foam layer 40 and the steering wheel frame 10 can be monitored at the DB point. When the second foam layer 40 has weak conductivity and is in contact with a human hand 2, the Cdb value of the second foam layer 40 with weak conductivity is larger because the second foam layer 40 with weak conductivity is denser and closer to the human hand 2, and the effective projected area of ​​the human hand 2 is larger.

[0055] According to some embodiments of this application, such as Figures 6-7 As shown, the steering wheel assembly 1 for a vehicle also includes a capacitance sensing layer 30, which is disposed between the first foam layer 20 and the second foam layer 40 and has conductive properties; wherein, the detection device 60 is electrically connected to the second foam layer 40 and / or the capacitance sensing layer 30. Specifically, the capacitance sensing layer 30 can be selected from one or more of flexible circuit boards, conductive films, conductive fabrics, or metal meshes, and its surface is distributed with multiple sensing electrodes for sensing capacitance changes. When a hand comes into contact with the second foam layer 40, the hand, the weakly conductive second foam layer 40, and the capacitance sensing layer 30 generate capacitance with each other. Compared to the hand directly contacting the second foam layer 40, this increases the total capacitance occupied by the human body, thereby improving the sensitivity of capacitance detection.

[0056] Furthermore, the detection device 60 can be electrically connected only to the second foam layer 40. In this case, the second foam layer 40, as a weakly conductive layer, directly contacts the human hand 2. The capacitance change formed by coupling is directly transmitted to the detection device 60 through the second foam layer 40, realizing the off-hand monitoring function. Alternatively, the detection device 60 can be electrically connected only to the capacitance sensing layer 30. In this case, the second foam layer 40, as a weakly conductive electric field coupling medium, shortens the sensing distance between the human hand 2 and the capacitance sensing layer 30 to approximately zero. The capacitance sensing layer 30 detects the capacitance change caused by the human hand 2 approaching or contacting it and transmits the signal to the detection device 60, improving the off-hand monitoring sensitivity. Alternatively, the detection device 60 can be electrically connected to the second foaming layer 40 and the capacitive sensing layer 30 respectively. In this case, the detection device 60 can simultaneously collect the capacitance signals of the second foaming layer 40 and the capacitive sensing layer 30, and judge the hand contact status by comprehensively judging the signals, thereby further improving the detection accuracy and reliability. At the same time, if one signal path is abnormal, the other path can still maintain the off-hand monitoring function, ensuring that the off-hand detection function is normal and improving the system reliability.

[0057] It is worth mentioning that in the steering wheel assembly 1 designed according to this application, since the second foam layer 40 has weak conductivity, the second foam layer 40 forms a capacitive electrode, which can realize off-hand detection without the need to set up a separate capacitive sensing layer 30, thus reducing the cost. In the aforementioned embodiment, designing a capacitive sensing layer 30 on the basis of setting up the second foam layer 40 can further improve the off-hand detection sensitivity.

[0058] exist Figure 7 In the illustrated embodiment, the steering wheel assembly 1 includes a steering wheel frame 10, a first foam layer 20, a capacitive sensing layer 30, and a second foam layer 40. The capacitance Cab between the capacitive sensing layer 30 and the steering wheel frame 10 can be monitored at points A and B. When the second foam layer 40 is non-conductive and the hand 2 is not in contact, the capacitance Cab at point A and B is C3; when the second foam layer 40 is non-conductive and the hand 2 is in contact, the capacitance Cab at point A and B is C3 + [C1*C2 / (C1+C2)]; when the second foam layer 40 is weakly conductive and the hand 2 is in contact, the capacitance Cab at point A and B is C3 + {C2*[C1+C4*C5 / (C4+C5)] / C2+C1+C4*C5 / (C4+C5)}. In other words, since the second foam layer 40 with weak conductivity is denser and closer to the hand 2, and the effective projected area of ​​the hand 2 is larger, C4 is much larger than C1; at the same time, since the second foam layer 40 with weak conductivity completely seals and wraps the capacitive sensing layer 30, the distance between it and the capacitive sensing layer 30 is 0, so C3 is much larger than C1. Therefore, the Cab value of the second foam layer 40 with weak conductivity is larger.

[0059] According to some embodiments of this application, in the thickness direction of the second foam layer 40, the concentration of the weakly conductive material closer to the hand 2 is higher than that closer to the capacitive sensing layer 30. Specifically, the distribution of the weakly conductive material in the second foam layer 40 is not uniform, but exhibits a gradient distribution characteristic along the thickness direction, with a higher concentration of the weakly conductive material closer to the radial outer side of the steering wheel and a lower concentration closer to the radial inner side of the steering wheel.

[0060] During the foaming process of the second foam layer 40, a layered injection molding process can be adopted. First, a raw material with a lower concentration of weakly conductive material is injected, followed by a raw material with a higher concentration of weakly conductive material. This creates a continuous gradient transition between the two layers, resulting in a concentration gradient of weakly conductive material in the thickness direction of the second foam layer 40, with the outer layer having a higher concentration than the inner layer. This design optimizes capacitive coupling efficiency, makes the electric field distribution more uniform, and improves the smoothness and stability of the detection signal, thus enhancing signal stability. Simultaneously, the lower concentration in the inner layer of the second foam layer 40 ensures a good grip on the steering wheel, while the higher concentration in the outer layer guarantees the conductivity of the second foam layer 40. Furthermore, it reduces the overall amount of weakly conductive material used while maintaining the conductivity of the second foam layer 40, thereby lowering material costs.

[0061] According to some embodiments of this application, the first foam layer 20 is a polyurethane foam layer that is foamed and molded onto the steering wheel frame 10 in one step. Specifically, the first foam layer 20 is made of polyurethane foam material, which has good fluidity, resilience and formability. After foaming and molding, the texture is uniform and the surface is smooth, which can provide good cushioning performance and grip feel for the steering wheel.

[0062] In some embodiments, the steering wheel assembly 1 may also have a heating function, which includes a heating pad. The conductivity of the second foam layer 40 is not affected by the heating pad; only insulation protection is needed between the second foam layer 40 and the heating pad to prevent electrical short circuits. Furthermore, the capacitive sensing layer 30 also has a heating function.

[0063] According to this application, the steering wheel assembly 1 is applicable to a capacitive off-hand capacitive sensing layer 30 with enameled wire and / or metal cloth scheme, and also to a capacitive sensing layer 30 with single-layer enameled wire time-division multiplexing control.

[0064] For the detection device 60, such as Figures 8-9 As shown, the detection device 60 can be an ECU controller, which is communicatively connected to the vehicle controller. The ECU controller system includes capacitance detection, vehicle body power supply and communication, optional heating functions, and other functions. The core function of HOD is to measure the magnitude and change of the sensing capacitance. The steering wheel assembly 1 may only have HOD function (e.g., Figure 8 As shown), it can also have both HOD and heating functions (such as...). Figure 9As shown), it employs a time-division multiplexing control method and can only use enameled wire, not metal cloth. Figure 10 As shown, the software of the ECU controller system needs to handle algorithms and logic such as data filtering, reference value maintenance, temperature drift correction, status determination, and fault detection.

[0065] like Figure 11 As shown, when the hand 2 is not in contact, the value of the sensing capacitance C is called the base value, which is the capacitance value between the sensing electrode and the steering wheel frame 10 and the surrounding space; when the hand 2 is in contact, the capacitance increases and exceeds the set threshold, which is when it is determined that there is a hand.

[0066] In some specific embodiments, the preparation process of the second foaming layer 40 is as follows: Step 1: Preparation and Classification of Conductive Micropowder. A weakly conductive material (preferably carbon black, carbon nanotubes, conductive carbon fibers, or a combination thereof) is physically pulverized in a high-speed air jet mill or ball mill. The pulverization process parameters are controlled (e.g., air pressure 0.6-0.8 MPa, grinding media diameter 0.1-0.5 mm) to ensure the particle size D90 (the cumulative 90% particle size distribution) of the weakly conductive material is between 1 μm and 10 μm. Subsequently, an air classifier is used to remove ultrafine powder smaller than 0.5 μm (to prevent excessive agglomeration) and coarse particles larger than 20 μm (to prevent the formation of macroscopic conductive spots), obtaining conductive micropowder with a concentrated particle size distribution. This step aims to form individual conductive units from the weakly conductive material, rather than a continuous conductive layer.

[0067] Step 2: Substrate Mixing and Pre-dispersion. Select polyurethane foaming raw materials, including a polyol component (Component A) and an isocyanate component (Component B). Add the conductive micropowder prepared in Step 1 to the polyol component (Component A) at a weight percentage of 3%-15%. Simultaneously add a coupling agent (such as a titanate coupling agent, added at 0.5%-2% of the weight of the conductive micropowder) and a dispersant (such as a high molecular weight polyurethane dispersant). Stir using a high-speed disperser at 1500-3000 rpm for 30-60 minutes to form a uniform and stable suspension dispersion of the conductive micropowder in the polyol, ensuring that the conductive micropowder is encapsulated by the organic coating layer and preventing direct agglomeration.

[0068] Step 3: Foaming and Conductive Network Reconstruction. The polyol component (component A) mixed with conductive micropowder and the isocyanate component (component B) are injected into the steering wheel mold through a high-pressure foaming machine mixing head in a specific ratio (typically A:B weight ratio of 100:60-100:80). A steering wheel frame 10 covered with the first foam layer 20 is pre-placed in the mold. The mixture undergoes a polymerization reaction and foaming within the mold.

[0069] During the foaming process, as the polyurethane molecular chains grow and cross-link, the conductive microparticles (conductive islands) originally uniformly dispersed in the liquid phase are "pushed away" and "fixed" by the gradually growing polyurethane molecular chains. Due to the phase separation effect of the foaming process, the conductive microparticles are eventually displaced and enriched on the pore walls and pillars of the polyurethane foam, forming a "pearl necklace"-like conductive network structure. These conductive microparticles are not in complete contact with each other, but form weak conductive pathways through tunneling effects or tiny gaps. By precisely controlling the amount of conductive microparticles added (e.g., 5%-12%) and the foaming process (e.g., mold temperature controlled at 50-70°C, demolding time 5-8 minutes), the resulting second foamed layer 40 exhibits macroscopically weak conductive properties, and its surface sheet resistance is precisely controlled at 10. 3 ~10 6 Within the range.

[0070] Step 4, Post-processing and Gradient Concentration Control (Optional): To achieve better touch sensitivity, based on the above process, a secondary injection molding or in-mold spraying process can be used to form a surface layer with a thickness of 0.05-0.3 mm and a higher concentration of conductive micropowder on the surface of the second foam layer 40 (near the hand). For example, at the moment the mold opens, a polyurethane liquid containing conductive micropowder is sprayed into the cavity, allowing it to fuse with the surface layer of the curing second foam layer 40. This ultimately forms a structure with an increasing concentration gradient of conductive micropowder from the inside out, meaning the concentration of the weakly conductive material near the hand 2 is higher than that near the capacitive sensing layer 30. This structure can enhance the capacitive coupling efficiency when the hand contacts the object, while maintaining sufficient internal insulation to reduce accidental touches and power consumption.

[0071] Through the above design, the capacitance detection formula and dual threshold judgment method provided in this application upgrade the traditional single capacitance change judgment to a comprehensive judgment of the change slope and absolute value. Combined with the stable coupling path provided by the weak conductive layer, it can effectively shield interference from rain, sweat, gloves, etc., and achieve high-precision "bare hand-with-glove" compatible recognition, thus improving the detection reliability.

[0072] Furthermore, by employing a "break-up and reconstruction" process for manufacturing weakly conductive materials, the dilemma of insulation versus conductivity in traditional solutions was overcome, allowing for optimization of material properties. The resulting weakly conductive foam layer maintains the softness, wear resistance, and weather resistance of polyurethane while possessing stable and uniform weak conductivity. Its three-dimensional "pearl necklace" conductive network structure ensures macroscopic electrical conductivity while avoiding "hard spots" or "bright spots" caused by completely continuous conductive materials, perfectly matching the appearance and tactile requirements of the steering wheel.

[0073] Meanwhile, the detection function is directly integrated into the outermost foam layer. Compared with the traditional method of embedding metal wires or thin film sensors under the steering wheel leather, the structure of this application is simpler, the assembly process is more user-friendly, and the cost is lower. Moreover, since the weakly conductive material is part of the second foam layer 40, there are no problems such as sensor detachment or displacement, resulting in extremely high reliability and lifespan.

[0074] The core of this application lies in utilizing the weak conductivity of the second foam layer 40 to construct a stable and quantifiable capacitance detection model. When a human hand 2 approaches or touches the surface of the second foam layer 40, a coupling capacitance is formed between the human body and the second foam layer 40. The detection device 60 determines the touch state by detecting the change in this capacitance. To accurately and reliably identify touches, this application establishes the following detection and determination mechanism, assuming the total capacitance detected by the detection device 60 is C, which consists of the basic capacitance Co and the capacitance change ΔC caused by the touch, C = Co + ΔC. The basic capacitance Co includes the parasitic capacitance of the steering wheel assembly itself and the environmental noise capacitance. When the human hand 2 contacts the second foam layer 40, the coupling capacitance ΔC can be approximately equivalent to a planar capacitor model between a human hand and the weakly conductive layer: △C=ε0*εr*S / d; Wherein, ε0 is the vacuum dielectric constant, εr is the equivalent relative dielectric constant of the contact interface between the second foam layer 40 and the human hand 2, S is the actual contact area between the human hand 2 and the second foam layer 40, and d is the equivalent contact distance. Since there is a gap between the human hand 2 and the surface of the weakly conductive layer, this value is between the thickness of the stratum corneum of the human hand skin and the air gap at the interface.

[0075] Furthermore, considering that the second foamed layer 40 itself has weak conductivity (surface sheet resistance of 10), 3 ~10 6 (Between Ω), it is not an ideal insulator. Therefore, the actual sensing model of the detection device 60 should be a resistance-capacitance coupling model. When the hand 2 touches, the detection signal forms a conductive path through the weakly conductive network of the second foam layer 40, and the signal amplitude V detected by the detection device 60 is... sense The contact intensity satisfies the following relationship: Among them, V drive The drive signal emitted by the detection device 60 That is, the human body equivalent impedance Z body Equivalent impedance Z of the second foam layer layer The parallel value of Z (" / / " is the abbreviation for parallel connection). ref To detect the reference impedance. When a person touches the steering wheel, The value of changes, causing the signal amplitude V to change. sense Changes are detected by the detection device as touch.

[0076] The comparator or microcontroller unit (MCU) built into the detection device 60 is configured to determine a valid touch when the change in C exceeds a preset contact slope threshold and the absolute value of ΔC is greater than a preset contact capacitance threshold within a continuous sampling period. This dual-threshold determination method (slope + absolute value) can effectively distinguish between human hand touch and unexpected events such as electromagnetic interference and water splashes, greatly improving the robustness of the detection.

[0077] The vehicle according to this application is briefly described below.

[0078] The vehicle according to this application includes the steering wheel assembly 1 for a vehicle as described in any of the above embodiments. Since the vehicle according to this application is equipped with the steering wheel assembly 1 for a vehicle as described in the above embodiments, the vehicle has better safety performance.

[0079] In summary, according to the steering wheel assembly 1 for vehicles of this application, by designing the second foam layer 40 to have weak conductivity and to be in direct contact with the human hand 2, the sensing distance is shortened. Since the entire second foam layer 40 also serves as part of the sensing electrode, the effective sensing area is increased. As the sensing capacitance is directly proportional to the sensing area S and inversely proportional to the sensing distance d in the principle of capacitive sensing, the steering wheel assembly 1 designed according to this application, due to the shortened sensing distance and increased effective sensing area, allows the hands-off monitoring system to obtain a larger capacitance change, thereby improving the sensitivity and signal stability of hands-off monitoring. Furthermore, the hands-off monitoring system has high judgment accuracy, a good user experience, and enhances vehicle safety and intelligence.

[0080] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0081] Although embodiments of this application have been shown and described above, variations, modifications, substitutions and alterations can be made to the above embodiments.

Claims

1. A steering wheel assembly for a vehicle, characterized in that, include: Steering wheel frame (10); The first foam layer (20) covers the outside of the steering wheel frame (10); The second foam layer (40) covers the outside of the first foam layer (20) and serves as the outermost layer to directly contact the human hand (2). The second foam layer (40) is made of or doped with a weakly conductive material to give it weakly conductive properties. The second foam layer (40) is used to couple with the human hand (2) to form a capacitor. The detection device (60) is adapted to detect the capacitance change caused by a human hand approaching or touching the second foam layer (40).

2. The steering wheel assembly for a vehicle according to claim 1, characterized in that, The surface sheet resistance of the second foamed layer (40) is 10. 3 ~10 6 Ω.

3. The steering wheel assembly for a vehicle according to claim 1, characterized in that, The second foam layer (40) is a polyurethane foam layer doped with a weakly conductive material.

4. The steering wheel assembly for a vehicle according to claim 1, characterized in that, The weakly conductive material includes at least one of carbon black, carbon nanotubes, conductive fibers, and conductive powder.

5. The steering wheel assembly for a vehicle according to claim 1, characterized in that, The detection device (60) is electrically connected to the second foaming layer (40).

6. The steering wheel assembly for a vehicle according to claim 5, characterized in that, The detection device (60) is mounted on the steering wheel frame (10); The second foam layer (40) has an embedded conductor (50) that extends along the outline of the steering wheel frame (10) and is electrically connected to the detection device (60).

7. The steering wheel assembly for a vehicle according to claim 1, characterized in that, Also includes: A capacitive sensing layer (30) is disposed between the first foam layer (20) and the second foam layer (40) and has conductive properties; wherein, The detection device (60) is electrically connected to the second foaming layer (40) and / or the capacitive sensing layer (30).

8. The steering wheel assembly for a vehicle according to claim 7, characterized in that, In the thickness direction of the second foamed layer (40), the concentration of the weakly conductive material on the side closer to the hand (2) is higher than the concentration on the side closer to the capacitive sensing layer (30).

9. The steering wheel assembly for a vehicle according to claim 1, characterized in that, The first foam layer (20) is a polyurethane foam layer that is foamed and molded on the steering wheel frame (10) in one step.

10. A vehicle, characterized in that, Includes a steering wheel assembly for a vehicle according to any one of claims 1-9.

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