Steering wheel device

Abstract

To provide a steering wheel device that provides a feeling of warmth regardless of grip position. [Solution] The steering wheel device 10 comprises an annular adapter 12 that conforms to the shape of the grip portion 15, and a heater mat 13 that is arranged to wrap around the surface of the adapter 12. The heater mat 13 has multiple heating wires 40 that are used as both heating wires for heating and signal wires for sensors, and are individually arranged in multiple wiring regions. The multiple wiring regions extend in a direction along the annular shape of the adapter 12 and are aligned along the circumferential direction in a cross-section perpendicular to the direction along the annular shape of the adapter 12.

Description

Technical Field

[0001] The present invention relates to a steering wheel device.

Background Art

[0002] Conventionally, there is a steering wheel device with a built-in heater for warming the hands of passengers when driving a car in cold weather. Patent Document 1 discloses a technique related to a conductive heater that can also function as a sensor for detecting the presence of a passenger and can be adopted in a steering wheel device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The conductive heater disclosed in Patent Document 1 is shown in a form divided along the rotation direction of the steering wheel. However, considering the installation position of the power application part, it is conceivable that there will be variations in warmth depending on the gripping position by the passenger.

[0005] The present invention has been made in view of the problems of such conventional techniques. The object of the present invention is to provide a steering wheel device that feels warm regardless of the gripping position.

Means for Solving the Problems

[0006] A steering wheel device according to an aspect of the present invention comprises an annular base material conforming to the shape of the gripping portion, and a heater mat arranged to be wrapped around the surface of the base material. The heater mat has multiple heating wires, each individually arranged in a plurality of wiring regions, which are dual-purpose wires serving as both heating wires and signal wires as sensors. The plurality of wiring regions extend in a direction along the annular shape of the base material and are aligned along the circumferential direction in a cross-section perpendicular to the direction along the annular shape of the base material. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a steering wheel device that provides a feeling of warmth regardless of the grip position. [Brief explanation of the drawing]

[0008] [Figure 1] This is an exploded perspective view of a steering wheel device according to one embodiment. [Figure 2] This is a plan view of the heater mat. [Figure 3A] This is a front view of the steering wheel device held by the occupant. [Figure 3B] This is a cross-sectional view of the steering wheel device held by the occupant. [Figure 4A] This is a front view of the steering wheel mechanism as it is touched by the occupant. [Figure 4B] This is a cross-sectional view of the steering wheel mechanism as it is touched by the occupant. [Figure 5] This is a wiring diagram of a steering wheel device according to one embodiment. [Figure 6] This wiring diagram shows an example of current setting during energization control based on the first control pattern. [Figure 7] This chart shows the control flow based on the first control pattern. [Figure 8] This graph shows the current switching timing and other parameters in the first control pattern. [Figure 9] This wiring diagram shows an example of current setting during energization control based on the second control pattern. [Figure 10] This graph shows the current switching timing and other parameters in the second control pattern. [Figure 11] This graph shows the current switching timing and other parameters in the third control pattern. [Figure 12] This graph shows the current switching timing and other parameters in the fourth control pattern. [Modes for carrying out the invention]

[0009] The following describes in detail a steering wheel device according to one embodiment, using the drawings. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0010] Figure 1 is an exploded perspective view of a steering wheel device 10 according to one embodiment. The steering wheel device 10 is a device installed in a vehicle such as an automobile, which is operated by the occupant driving the vehicle to adjust the direction of travel of the vehicle. Hereinafter, the part of the steering wheel device 10 that is assumed to be gripped by the occupant will be referred to as the "grip portion 15" (see Figures 3A and 3B). In this embodiment, the grip portion 15 corresponds to an annular portion of the steering wheel device 10 that has a shape along the direction of rotation. The steering wheel device 10 comprises a core material 11, an adapter 12, a heater mat 13, a covering portion 14, and an ECU 20. In Figure 1, among the components of the steering wheel device 10, the components that are higher up are closer to the occupant sitting in the driver's seat.

[0011] The core material 11 is a skeletal member of the steering wheel device 10. The core material 11 has an annular rim core material 11a, a spoke core material 11b that supports the rim core material 11a, and a boss core material 11c that supports the spoke core material 11b. The core material 11 is manufactured by die casting using, for example, a magnesium alloy as the material.

[0012] Adapter 12 is a base material for installing the heater mat 13. The adapter 12 has a first adapter 12a and a second adapter 12b. The first adapter 12a and the second adapter 12b are combined with each other to form a hollow annular shape. The adapter 12 encloses the rim core material 11a in the hollow part and is fixed to the core material 11. That is, the outer shape of the adapter 12 conforms to the surface shape of the grip portion 15. Assuming that the annular adapter 12 is divided by a plane connecting the outer circumference and the inner circumference, the divided body located on the front side is the first adapter 12a, and the divided body located on the rear side is the second adapter 12b. Here, the front side refers to the side facing the occupant who operates the steering wheel device 10, and the rear side refers to the opposite side of the front side. Also, the first adapter 12a and the second adapter 12b are made of synthetic resin and are combined with each other by, for example, adhesion. Incidentally, the inside of the adapter 12 may be filled with a filler made of a soft material such as foamed polyurethane provided so as to cover the rim core material 11a.

[0013] Figure 2 is a plan view of the heater mat 13 before being incorporated into the steering wheel device 10. The heater mat 13 functions as a heater for warming the grip portion 15 of the steering wheel device 10 and also functions as a sensor for detecting the contact of the occupant.

[0014] The heater mat 13 is generally a single-layer sheet-like shape that can be deformed according to the surface shape of the member to be installed. The heater mat 13 has a sheet material 13a and a plurality of heating wires 40 arranged in a pattern on the sheet material 13a. In FIG. 2, a part of one heating wire 40 is illustrated by a broken line. Since the sheet material 13a is wound and installed on the adapter 12, it is desirable that it has excellent stretchability. For example, it is desirable that it is a foamed resin sheet or a foamed rubber sheet. The plurality of heating wires 40 are, for example, copper alloy wires and are connected to the ECU 20.

[0015] Further, as shown in FIG. 2, the heater mat 13 is long and strip-shaped along one direction. The heater mat 13 is wound around the adapter 12 such that the longitudinal direction of the heater mat 13 follows the annular shape which is the overall shape of the adapter 12. Here, the direction along the annular shape of the adapter 12 is synonymous with the rotational direction of the steering wheel device 10 corresponding to the first direction D1 in FIG. 3A. At the same time, the heater mat 13 is wound around the adapter 12 such that the width direction of the heater mat 13 orthogonal to the longitudinal direction follows the outer periphery in the cross-section of each part of the adapter 12. Here, the direction along the outer periphery in the cross-section of each part of the adapter 12 corresponds to the circumferential direction in the cross-section orthogonal to the core material 11 in each part of the steering wheel device 10 corresponding to the second direction D2 in FIG. 3B. Note that the heater mat 13 may be configured as a single unit extending over the entire circumference of the steering wheel device 10 along the first direction D1, or may be configured by being divided into a plurality of parts.

[0016] Furthermore, in the heater mat 13, a plurality of wiring regions for individually arranging a plurality of heating wires 40 are set. The plurality of wiring regions are each strip-shaped along the longitudinal direction of the heater mat 13 and are arranged in parallel with each other. In the present embodiment, as an example, as shown in FIG. 2, three wiring regions, i.e., a first wiring region R1, a second wiring region R2, and a third wiring region R3, are set in the heater mat 13. The first wiring region R1 is a wiring region set in the central region in the width direction of the heater mat 13. The second wiring region R2 and the third wiring region R3 are wiring regions set in the end regions sandwiching the first wiring region R1 in the width direction of the heater mat 13.

[0017] Note that the wiring pattern of the heating wires 40 arranged for each wiring region can be set as appropriate. Also, it is not limited to the case where only one heating wire 40 is arranged for one wiring region, and a plurality of heating wires 40 may be arranged. Further, although the boundary between adjacent wiring regions is schematically shown as a dashed line in FIG. 2, for example, it may include a curved portion in part.

[0018] Figures 3A and 3B show the steering wheel device 10 being held by the occupant with an overhand grip.

[0019] Figure 3A is a front view of the steering wheel device 10 as seen from the occupant's perspective. The gripping position shown in Figure 3A corresponds to the gripping position during normal driving, with the occupant's hands 100 positioned on the gripping portion 15 such that the gripping positions of the left hand 100a and the right hand 100b are symmetrical. The first direction D1 indicated by the arrow in Figure 3A is the rotation direction of the steering wheel device 10.

[0020] Figure 3B is a cross-sectional view of the steering wheel device 10 near the left hand 100a shown in Figure 3A. The heater mat 13 is positioned on the adapter 12, for example, such that the first wiring area R1 is located in the outer peripheral area of ​​the adapter 12. In this case, the second wiring area R2 may be located in the side area of ​​the adapter 12 facing the occupant, and the third wiring area R3 may be located in the side area opposite to the side facing the occupant.

[0021] Figures 4A and 4B show the steering wheel device 10 being simply touched by the occupant.

[0022] Figure 4A is a front view of the steering wheel device 10 as seen from the occupant's perspective. As an example, Figure 4A shows the occupant touching the surface of the gripping part 15 with the palm of their left hand 100a.

[0023] Figure 4B is a cross-sectional view of the steering wheel device 10 near the left hand 100a shown in Figure 4A. When an occupant in a normal driving position attempts to touch the gripping part 15 with their left hand 100a as shown in Figure 4A, a portion of their palm will touch the area of ​​the gripping part 15 on the first wiring area R1 and the area of ​​the gripping part 15 on the second wiring area R2.

[0024] The heater mat 13 also includes a steering heater switch 30 and a thermistor 31 (see Figure 5). The steering heater switch 30 is a thermostat that turns off when the temperature of the heater mat 13 rises excessively. The thermistor 31 is a temperature sensing element that feeds back information about the temperature of the heater mat 13 to the ECU 20. Note that the steering heater switch 30 and thermistor 31 are not shown in Figure 2 for convenience.

[0025] The covering portion 14 is a surface member of the steering wheel device 10. The covering portion 14 may be made of, for example, leather, or it may be formed by injection reaction molding using soft foamed polyurethane as the material.

[0026] Figure 5 is a wiring diagram of the steering wheel device 10.

[0027] The ECU 20 is an electronic control unit that controls at least the heater function and sensor function of the steering wheel device 10. Although not shown, the ECU 20 incorporates a CPU (Central Processing Unit) that executes control operations in a predetermined procedure, and a ROM (Read-Only Memory) that stores control programs for controlling various operations. The ECU 20 may also be built into the steering wheel device 10.

[0028] Multiple heating wires 40 provided on the heater mat 13 are connected to the ECU 20 via the first connector 50. In this embodiment, the heating wires 40 serve as both heating wires and signal wires for occupant detection. In Figure 5, for convenience, multiple heating wires 40 are depicted as a single dashed line. The steering heater switch 30 is electrically connected to the ECU 20 via the first wire 41 and the first connector 50, and is also electrically connected to the vehicle-side wires 200 via the first wire 41 and the second connector 51.

[0029] The thermistor 31 is electrically connected to the ECU 20 via the second wire 42 and the third connector 52. The ECU 20 receives the output voltage corresponding to the resistance change of the thermistor 31 and measures the temperature of the heater mat 13 based on this output voltage. A ground wire 43, one end of which is connected to a rim core material 11a made of metal, is connected to the third connector 52. The third connector 52 is also electrically connected to the fourth connector 53 via a wire group 44, and the fourth connector 53 is connected to the vehicle-side wire 200. The wire group 44 includes communication lines and ground lines, etc.

[0030] Next, the control of the heater mat 13 by the ECU 20 will be described. The heater mat 13 has three independent heating elements 40 arranged in each wiring area. The ECU 20 individually controls the power supply to each heating element 40 arranged in each wiring area. Below, four control patterns that the ECU 20 can appropriately execute will be illustrated.

[0031] Herein, in explaining the control of the heater mat 13, the following terms are defined: "Heating" refers to warming the gripping part 15 so that when a part of the occupant touches the gripping part 15, it provides a feeling of warmth. "Sensing" refers to detecting whether a part of the occupant is touching the gripping part 15. In this context, the part of the occupant is usually the palm of the occupant's hand 100.

[0032] First, the energization control for the heating wires 40 in each wiring area, based on the first control pattern, will be explained. The first control pattern refers to a control pattern in which the first wiring area R1 functions mainly as a sensing area, and the second wiring area R2 and the third wiring area R3 function mainly as heating areas. Referring to Figure 3B, according to the arrangement of the heater mat 13 in the steering wheel device 10, when the occupant is gripping a part of the gripping part 15, the palm of the hand 100 is likely to face the first wiring area R1. In other words, the first wiring area R1 is a wiring area suitable for prioritizing sensing because a touch response is easily obtained due to its positional relationship with the palm. On the other hand, similarly when the occupant is gripping a part of the gripping part 15, the fingertips of the hand 100 are likely to face the second wiring area R2 or the third wiring area R3. In other words, the second wiring area R2 or the third wiring area R3 can quickly warm the fingertips, which tend to get colder than the palm, making them suitable wiring areas for prioritizing heating.

[0033] Figure 6 is a wiring diagram showing an example of current settings during energization control based on the first control pattern. In the first control pattern, the ECU 20 switches between the current value that energizes the heating wire 40 located in the first wiring area R1 and the current value that energizes the heating wire 40 located in the second wiring area R2 or the third wiring area R3, at the timings and intervals exemplified below. In this embodiment, the current value that energizes the heating wire 40 located in the wiring area where heating is to be performed is set to 10A. When a current of 10A is applied, the heating wire 40 functions as a heating element. On the other hand, the current value that energizes the heating wire 40 located in the wiring area where sensing is to be performed is set to 3A. When a current of 3A is applied, the heating wire 40 functions as a signal line that transmits a signal to sense contact with an occupant. Figure 6 illustrates the power supply control state at a time when the ECU 20 is performing power supply control based on the first control pattern, and sensing is being performed in the first wiring region R1, while heating is being performed in the second wiring region R2 or the third wiring region R3. In Figure 6, the resistance values ​​set for the corresponding heating wires 40 are shown as examples for each wiring region.

[0034] Figure 7 is a flowchart showing the control flow of the heater mat 13 based on the first control pattern.

[0035] First, the ECU 20 determines whether the steering heater switch 30 is ON (step S101). If it is determined that the steering heater switch 30 is NOT ON (NO), the ECU 20 may perform sensing only in all wiring areas (step S102). In this case, the ECU 20 sets the current value for energizing all heating elements 40 to 3A. Step S102 may be performed until it is determined in step S101 that the steering heater switch 30 is ON.

[0036] On the other hand, in step S101, if it is determined that the steering heater switch 30 is ON (YES), the ECU 20 determines whether the measured temperature of the thermistor 31 is lower than a preset temperature (step S103). If it is determined that the measured temperature of the thermistor 31 is not lower than a preset temperature (NO), the ECU 20 may perform 8ms of sensing every 80ms in all wiring areas (step S104). In this case, the ECU 20 sets the current value supplied to all heating wires 40 to 3A while sensing is being performed, and sets the current value supplied to all heating wires 40 to 10A while sensing is not being performed, i.e., while heating is being performed. On the other hand, if it is determined that the measured temperature of the thermistor 31 is lower than a preset temperature (YES), the ECU 20 executes step S105.

[0037] Figure 8 is a graph showing an example of the current switching timing for each wiring region in step S105 based on the first control pattern. In step S105, first, the ECU 20 may set the current value supplied to the heating element 40 to mainly 10A in the first wiring region R1 to perform heating, and then switch the current value to 3A for 8ms every 80ms to perform sensing. On the other hand, in the second wiring region R2 and the third wiring region R3, the ECU 20 may set the current value supplied to the heating element 40 to mainly 10A to perform heating, and then switch the current value to 3A for 8ms every 256ms to perform sensing. Here, the timing of sensing in the second wiring region R2 and the third wiring region R3 is matched to one of the timings of sensing in the first wiring region R1. This makes sensing more accurate or reliable in the heater mat 13.

[0038] Then, after the completion of step S104 or step S105, the ECU 20 may decide, for example, whether to change from the first control pattern to a control pattern different from the first control pattern (step S106). If it is decided not to change the control pattern (NO), the energization control based on the first control pattern will continue to be performed, and if it is decided to change the control pattern (YES), the energization control based on the first control pattern may be terminated.

[0039] Next, the energization control for the heating wires 40 in each wiring area, based on the second control pattern, will be explained. The second control pattern refers to a control pattern in which the first wiring area R1 is mainly used as a heating area, and the second wiring area R2 and the third wiring area R3 are mainly used as sensing areas. The first control pattern, which has already been explained, is suitable when the heater mat 13 is placed on the adapter 12, as illustrated in Figure 3B. In contrast, depending on the specific shape of the adapter 12, and consequently the specific shape of the steering wheel device 10, it may be preferable to prioritize heating in the first wiring area R1 and to prioritize sensing in the second wiring area R2 or the third wiring area R3.

[0040] Figure 9 is a wiring diagram showing an example of current settings during energization control based on the second control pattern. In the second control pattern, the ECU 20 switches between the current value supplied to the heating element 40 located in the first wiring area R1 and the current value supplied to the heating element 40 located in the second wiring area R2 or the third wiring area R3 at the timings exemplified below. Here, the current value supplied to the heating element 40 located in the wiring area where heating is to be performed is set to 10A. On the other hand, the current value supplied to the heating element 40 located in the wiring area where sensing is to be performed is set to 3A. Figure 9 exemplifies the energization control state at the timing when heating is performed in the first wiring area R1 and sensing is performed in the second wiring area R2 or the third wiring area R3 while the ECU 20 is performing energization control based on the second control pattern. In Figure 9, the resistance values ​​set for the corresponding heating element 40 for each wiring area are also exemplified.

[0041] Figure 10 is a graph showing an example of the current switching timing for each wiring region based on the second control pattern. In the first wiring region R1, the ECU 20 may primarily set the current value supplied to the heating element 40 to 10A to perform heating, while switching the current value to 3A for 8ms every 192ms to perform sensing. On the other hand, in the second wiring region R2 and the third wiring region R3, the ECU 20 may keep the current value supplied to the heating element 40 at 3A at all times to perform sensing.

[0042] Next, we will explain the energization control for the heating wires 40 in each wiring area based on the third control pattern. The third control pattern refers to a control pattern that switches only the current value supplied to the heating wires 40 located in the first wiring area R1.

[0043] Figure 11 is a wiring diagram showing an example of current settings during energization control based on the third control pattern. In the third control pattern, only the first wiring region R1 switches between functioning primarily as a sensing region and primarily as a heating region. In this case, the second wiring region R2 or the third wiring region R3 is always set to a current of 10A supplied to the heating element 40, and functions as a heating region. Figure 11 also shows examples of resistance values ​​set for the corresponding heating element 40 for each wiring region. According to the third control pattern, since only the first wiring region R1 switches between heating and sensing regions, the control is simplified compared to, for example, the first control pattern.

[0044] Next, we will explain the energization control for the heating wires 40 in each wiring area based on the fourth control pattern. The fourth control pattern is a control pattern in which the resistance value set for each heating wire 40 in each wiring area is set individually in advance, and the current value supplied to all heating wires 40 located in all wiring areas is switched uniformly at certain timings.

[0045] Figure 12 is a wiring diagram showing an example of current settings during energization control based on the fourth control pattern. In the fourth control pattern, the current value for all wiring areas is switched between 10A and 3A as appropriate, so that the heater mat 13 as a whole switches between prioritizing heating and prioritizing sensing. On the other hand, when the fourth control pattern is adopted, the resistance value to be set for the heating wire 40 is set individually in advance for each wiring area, as shown in Figure 12. With the fourth control pattern, the current value supplied to all heating wires 40 is switched uniformly, so the control is simplified compared to the first control pattern, etc., and it is possible to set which wiring area should be heated higher among the multiple wiring areas where heating is prioritized.

[0046] Next, the effects of the steering wheel device 10 will be explained.

[0047] The steering wheel device 10 comprises an adapter 12, which is an annular base material conforming to the shape of the grip portion 15, and a heater mat 13 arranged to wrap around the surface of the adapter 12. The heater mat 13 has multiple heating wires 40, which are dual-purpose wires that serve as both heating wires and signal wires for sensors, and are individually arranged in multiple wiring regions. The multiple wiring regions extend in a direction along the annular shape of the adapter 12 and are aligned along the circumferential direction in a cross-section perpendicular to the direction along the annular shape of the adapter 12.

[0048] Here, the multiple wiring regions correspond to the first wiring region R1, the second wiring region R2, and the third wiring region R3 in the above example. The direction along the annular shape of the adapter 12 corresponds to the first direction D1 in the above example. The circumferential direction in the cross-section perpendicular to the direction along the annular shape of the adapter 12 corresponds to the second direction D2 in the above example.

[0049] In the configuration of the steering wheel device 10, each wiring area where an individual heating element 40 is placed extends in a first direction D1 along the annular shape of the adapter 12, and is also aligned along a second direction D2, which is the circumferential direction in a cross-section perpendicular to the first direction D1. Therefore, in the parts of the gripping portion 15 where the heater mat 13 is placed, the width spacing of each wiring area is maintained at approximately a constant level in the first direction D1. Consequently, in the steering wheel device 10 in which the heater mat 13 has both a heating function and a sensor function, the occupant can feel the same level of warmth regardless of where they grip the steering wheel with their hand 100.

[0050] As described above, according to this embodiment, a steering wheel device 10 that provides warmth regardless of the grip position can be provided.

[0051] Furthermore, the steering wheel device 10 may include an ECU 20 that energizes multiple heating elements 40. The ECU 20 may control the current value when energizing each heating element 40 for each wiring area.

[0052] With the steering wheel device 10, the current value when energizing each heating element 40 is controlled for each wiring area, so that the area heated by the heater mat 13 can be freely allocated to each wiring area.

[0053] Furthermore, in the steering wheel device 10, each heating element 40 may switch between functioning as a heating element or a signal element based on the current value. Multiple wiring areas may be individually switched between areas where heating is prioritized and areas where sensing is prioritized, based on the timing and interval at which each heating element 40 switches to a signal element.

[0054] With the steering wheel device 10, for example, by setting the number of wiring areas that will be used as sensing areas to a minimum among multiple wiring areas, and designating the other wiring areas as heating areas, it is possible to prioritize temperature rise. In other words, with the steering wheel device 10, it is not necessary to refrain from performing sensing for a long period of time in order to prioritize temperature rise.

[0055] Furthermore, in the steering wheel device 10, one of the multiple wiring areas may be a first wiring area R1 located in the outer peripheral area of ​​the adapter 12. The first wiring area R1 may be an area where sensing is prioritized.

[0056] With the steering wheel device 10, as illustrated in Figure 3B, when the occupant is gripping a part of the gripping portion 15, the palm of the hand is more likely to face the first wiring area R1, which is advantageous in that it makes it easier to obtain a touch response.

[0057] In the above explanation, the timing and interval of sensing were exemplified using various numerical values, but other values ​​can also be freely set.

[0058] Although one embodiment has been described above, the embodiment is not limited to this, and various modifications are possible within the scope of the gist of the embodiment. [Explanation of Symbols]

[0059] 10. Steering wheel device 12 adapters 13 Heater Mat 15 Gripping part 20 ECU 40 Heating wire D1 1st direction D2 2nd direction R1 1st wiring area R2 2nd wiring area R3 3rd wiring area

Claims

1. An annular base material conforming to the shape of the gripping part, The facility comprises a heater mat arranged to be wrapped around the surface of the substrate, The heater mat has multiple heating wires, each individually arranged in multiple wiring areas, which are dual-purpose wires serving as both heating elements and signal lines for sensors. A steering wheel device in which multiple wiring regions extend in a direction along the annular shape of the base material and are arranged along the circumferential direction in a cross-section perpendicular to the direction along the annular shape of the base material.

2. It comprises an electronic control unit that energizes multiple heating elements, The steering wheel device according to claim 1, wherein the electronic control unit controls the current value when energizing each heating element in each wiring region.

3. Each of the aforementioned heating wires switches between functioning as a heating wire or a signal wire based on the current value. The steering wheel device according to claim 2, wherein each of the multiple wiring regions switches individually between a region where heating is prioritized and a region where sensing is prioritized, based on the timing and interval at which each of the heating wires switches to the signal line.

4. One of the plurality of wiring regions is a first wiring region located in the outer peripheral region of the substrate, The steering wheel device according to claim 3, wherein the first wiring region is a region in which sensing is prioritized.

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