handle

Abstract

To provide a handle capable of inexpensively stabilizing performance of a sensor part.SOLUTION: A handle 1 includes: a core bar 10 electrically connected to a reference potential GND; a coating part coating a part of the core bar 10; a sensor part 23 which has a sensor body part 24 provided with a shield electrode 26, a sensor electrode 27, and a dielectric body 28 mediated between the shield electrode 26 and the sensor electrode 27, and disposed on the coating part with the shield electrode 26 on the core bar 10 side, and a detection part 25 electrically connected to the shield electrode 26 and the sensor electrode 27; and a wiring 46 which is connected to a capacitive element 45, electrically connects the shield electrode 26 and the core bar 10, and is chargeable between the shield electrode 26 and the core bar 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a handle equipped with a sensor unit. [Background technology]

[0002] In recent years, steering wheels, which are the handles used to steer automobiles, have become known to incorporate a grip sensor in the rim, which is the gripping portion, to detect whether the driver is gripping the rim. The grip sensor is formed in a mat shape and is wrapped around the surface of a covering, such as a urethane foam layer, that covers the rim core metal that forms the core of the rim. The grip sensor can detect whether the driver is gripping the rim by detecting a change in capacitance between electrodes that occurs when the driver's hand moves toward or away from the rim (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-190856 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the capacitance between the electrodes of the grip sensor can easily vary with, for example, slight changes in the thickness of the coating covering the rim core or the amount of air bubbles contained in the coating, and products that show variations greater than specified must be calibrated one by one, which raises concerns about rising manufacturing costs.

[0005] The present invention has been made in consideration of the above points, and has as its object to provide a handle that can stabilize the performance of the sensor unit at low cost. [Means for solving the problem]

[0006] A handle according to one aspect of the present invention comprises a core electrically connected to a reference potential, a covering portion covering a portion of the core, a shield electrode, a sensor electrode, and an insulator interposed between the shield electrode and the sensor electrode, and further comprises a sensor main body portion disposed in the covering portion with the shield electrode on the core side, a detection portion electrically connected to the shield electrode and the sensor electrode, and wiring connected to a capacitance element, electrically connecting the shield electrode and the core and capable of being charged between the shield electrode and the core. [Effects of the Invention]

[0007] According to the present invention, it is possible to stabilize the performance of the sensor unit at low cost. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is an explanatory diagram schematically illustrating the electrical configuration of the handle according to the embodiment of the present invention. [Figure 2] FIG. 2 is an equivalent circuit diagram of the handle. [Figure 3] FIG. 3 is a cross-sectional view of the grip portion of the handle. [Figure 4] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] In FIG. 4, reference numeral 1 denotes a steering wheel (steering wheel) for steering a vehicle such as an automobile. In this embodiment, the steering wheel 1 is exemplified as a steering wheel having a central boss 2 surrounded by a rim (grip) 3, which is a circular or arc-shaped handle, and the boss 2 and rim 3 connected by radial spokes 4. However, the steering wheel 1 is not limited to this, and may be a control stick type, such as a so-called yoke type. The steering wheel 1 is normally mounted on a steering shaft, which is a steering shaft provided in a vehicle in an inclined state. In the following description, the direction of arrow U is the upper side and the direction of arrow D is the lower side when viewing the steering wheel 1 from the passenger's side. Furthermore, the position and shape of each part of the steering wheel 1 will be described based on the steering reference state, i.e., the neutral position, shown in FIG. 4.

[0011] The boss portion 2 is attached to the steering shaft and is located at the center of rotation of the steering wheel 1.

[0012] The rim portion 3 is the portion that the occupant (driver) grips to operate the steering wheel 1. In other words, the rim portion 3 is the portion used for steering. In this embodiment, the rim portion 3 is formed to extend in the direction of rotation of the steering wheel 1, i.e., the circumferential direction. In the example shown in the figure, the rim portion 3 is formed in an arc or annular shape.

[0013] There are multiple spokes 4. In this embodiment, three spokes 4 are provided to connect the left and right sides and the bottom of the boss 2 to the rim 3, but the number is not limited to this and may be, for example, two or four or more.

[0014] The handlebar 1 has a core (armature) 10 which is the main body of the handlebar. The core 10 is made of metal, such as a conductive alloy of aluminum or magnesium. The core 10 includes a boss core 12 which corresponds to the boss 2, a rim core 13 which serves as a grip core and corresponds to the rim 3, and spoke cores 14 which correspond to the spokes 4. The spoke cores 14 are formed integrally and continuously from the boss core 12, and the rim core 13 is fixed to the spoke cores 14 by welding or the like to form an integral unit. The rim core 13 and the connecting portions of the spoke cores 14 and the rim core 13 are covered with a covering 15.

[0015] The boss core metal portion 12 forms the core of the boss portion 2. The boss core metal portion 12 has a substantially cylindrical boss with a serration structure that meshes with the steering shaft. A module 17 such as an airbag device is disposed in the boss core metal portion 12. The boss portion 2 is formed by the boss core metal portion 12 and the module 17. The back side of the boss core metal portion 12 is covered by a cover body, which is also called a back cover, a lower cover, or a body cover.

[0016] The rim core metal portion 13 forms the core of the rim portion 3. In this embodiment, the rim core metal portion 13 is formed in an annular or arc shape that continues around the entire circumference.

[0017] The spoke cores 14 form the cores of the spokes 4. The spoke cores 14 are arranged radially from the boss core 12. Note that not all spokes 4 necessarily have spoke cores 14, and some spokes 4 may not have spoke cores 14 and may instead be made up of a finisher, cover, or the like.

[0018] The covering portion 15 is a resin layer formed from, for example, a synthetic resin. For example, a soft foamable resin such as urethane foam is used as the synthetic resin forming the covering portion 15. The covering portion 15 has a rim covering portion 20, which is the gripping main body that covers the rim core portion 13, and spoke covering portions 21 that cover the ends of the spoke core portions 14 that connect to the rim core portion 13.

[0019] The rim covering portion 20 is formed in a shape that is easy for a rider to grip, such as a circular or elliptical cross section.

[0020] The spoke covering portion 21 is continuous with the rim covering portion 20 and covers the end of the spoke core portion 14 on the rim core portion 13 side up to a position adjacent to the module 17 and the finisher.

[0021] As shown in Figure 3, the handlebar 1 is provided with a sensor unit 23 that detects the rider's grip on the rim unit 3. The sensor unit 23 is a capacitance sensor that detects the grip of the rim unit 3 by the user based on a change in capacitance, which will be described later. The sensor unit 23 includes a sensor main body 24 disposed in the cover 15, and a detection unit 25.

[0022] The sensor main body 24 is formed in a sheet or mat shape. The sensor main body 24 may be embedded in the covering portion 15, but in this embodiment, the sensor main body 24 is curved in the meridian direction, the cross-sectional circumferential direction, or the minor diameter direction of the rim portion 3 so as to wrap around the rim covering portion 20, and is wrapped around the covering portion 15 (rim covering portion 20) so that both side edge portions extending in the longitudinal direction face the inner edge side of the rim covering portion 20, that is, the side facing the boss portion 2, in other words, at a position on the rotation center side of the steering wheel 1, and face each other at a distance in the meridian direction.

[0023] The sensor main body 24 is configured by a shield electrode 26, also called a guard electrode, and a sensor electrode 27, which are arranged facing each other, with an insulator, a dielectric 28, interposed between the shield electrode 26 and the sensor electrode 27. The shield electrode 26 and the sensor electrode 27 are each formed of a conductive cloth or the like. The dielectric 28 is an insulator, such as a soft synthetic resin, such as olefin-based elastomer (TPO). The sensor main body 24 is wrapped around the rim cover 20 of the cover 15, with the shield electrode 26 facing the inside, i.e., the surface side of the cover 15, which is the side closest to the core 10, and the sensor electrode 27 facing the outside.

[0024] In this embodiment, the sensor main body 24, together with mainly the surface of the rim covering portion 20 of the covering portion 15, is covered by the skin body 30. The skin body 30 is formed in the shape of a thin sheet of natural leather, synthetic leather, synthetic resin, or the like, and is wrapped around the surface of the rim covering portion 20 to cover the entire rim covering portion 20. The skin body 30 is in close contact with the sensor electrode 27 and is set to the same electrical potential as the sensor electrode 27. In this embodiment, the surface of the skin body 30 forms the surface of the rim portion 3, but if the sensor main body 24 is embedded in the covering portion 15, the skin body 30 may not be provided.

[0025] The detection unit 25 periodically detects a differential signal between the input (AC voltage) to the shield electrode 26 and the output from the sensor electrode 27 as a voltage value, and detects the state of grip of the rim portion 3 by the user based on the differential signal. The detection unit 25 includes an amplifier that amplifies the output and a detection resistor that is a current-voltage conversion element. For example, an on-board control unit (ECU) or the like is used as the detection unit 25. The detection unit 25 is installed on the core bar 10 or the cover body, for example.

[0026] A heater or the like for warming the user's fingers may be provided on the handle 1. The heater may be formed in a sheet or mat shape and may be wrapped around the covering portion 15 or embedded in the covering portion 15, similar to the sensor main body 24 of the sensor unit 23.

[0027] Next, the principle of detection by the sensor unit 23 will be described.

[0028] 1 and 2, the shield electrode 26 and the sensor electrode 27 are directly electrically connected to the detection unit 25 by wires 35 and 36, which are lead wires, respectively. The reference potential of the detection unit 25 is directly electrically connected to the core 10 by wire 37, which is a lead wire, and is also directly electrically connected to the reference potential GND of the vehicle body by wire 38, which is a lead wire. The core 10 is also electrically connected to the reference potential GND of the vehicle body via the steering shaft 40. Therefore, the core 10 and the detection unit 25 are each set to substantially the same potential as the reference potential GND of the vehicle body. Furthermore, power is supplied to the detection unit 25 from the vehicle body via power supply lines 42 and 43.

[0029] In this electrical configuration, a capacitance Crs (=ε·S / d) is generated between the shield electrode 26 and the sensor electrode 27 in the sensor unit 23, and the capacitance Crs is determined by the opposing area S between the shield electrode 26 and the sensor electrode 27, the distance d, and the dielectric constant ε of the dielectric 28. A capacitance Csg is generated between the shield electrode 26 and the core 10. A capacitance Crgl, which is a structural parasitic capacitance, is generated between the sensor electrode 27 and the core 10.

[0030] When the user's hand H approaches or comes into contact with the rim 3, the detection unit 25 detects that the user is gripping the rim 3 in response to fluctuations in the differential signal due to the capacitance Chg that occurs between the hand H and the sensor electrode 27. The differential signal therefore has a value proportional to Chg / (Crs+Chg). Specifically, the detection unit 25 periodically counts the number of times that the detected differential signal is equal to or greater than a predetermined threshold, and if the count exceeds a predetermined number within a predetermined time period, it determines that the user is gripping the rim 3.

[0031] At this time, the capacitance Csg between the shield electrode 26 and the core 10 is charged by the input from the detection unit 25 to the shield electrode 26. Therefore, if there is a large variation in the capacitance Csg, there will be a large variation in the input to the shield electrode 26, i.e., the differential signal, and the number of counts will change.

[0032] Here, if the capacitance Csg is a parasitic capacitance that naturally occurs structurally between the shield electrode 26 and the core 10, it is due to factors such as variations in the thickness of the cover 15 (shown in FIG. 3) between the sensor main body 24 (shield electrode 26) and the core 10, variations in the area of the shield electrode 26 and / or the sensor electrode 27, and variations in the dielectric constant of the cover 15 (shown in FIG. 3) that are caused by the manufacturing process of the steering wheel 1. When the cover 15 is made of urethane foam or the like, variations in the dielectric constant of the cover 15 (shown in FIG. 3) are one of the factors that arise from the size of the air gap within the cover 15. This capacitance Csg is typically approximately 250 to 350 pF, and even if the steering wheel 1 is equipped with a heater, it is approximately 1300 to 1800 pF due to the influence of the heater's heat rays. In these cases, the ratio of the minimum value to the maximum value, which indicates the variation in capacitance Csg, is approximately 1.4 to 1.385.

[0033] Therefore, in this embodiment, the shield electrode 26 and the metal core 10 are electrically connected via wiring 46 connected to the capacitance element 45, and the wiring 46 is configured to be capable of charging between the shield electrode 26 and the metal core 10. That is, the wiring 46 is provided so that the capacitance element 45 is electrically connected in parallel to the capacitance Csg1 structurally generated between the shield electrode 26 and the metal core 10. As a result, the capacitance Csg is the composite capacitance (sum) of the capacitance Csg1 structurally generated between the shield electrode 26 and the metal core 10 and the capacitance Csg2 of the capacitance element 45. That is, Csg = Csg1 + Csg2. The capacitance element 45 is, for example, a capacitor. The capacitance Csg2 of the capacitance element 45 is larger than the capacitance Csg1 structurally generated between the shield electrode 26 and the metal core 10 (Csg2 >> Csg1), and is, for example, approximately 5000 pF.

[0034] Therefore, in the present embodiment, compared to capacitance Csg1 that is structurally generated between shield electrode 26 and core 10, which may cause variation in capacitance Csg, capacitance Csg2 of capacitive element 45, which has a large value and variation that is within the component tolerance, becomes dominant, thereby suppressing variation in capacitance Csg and bringing the ratio between the minimum and maximum values of capacitance Csg closer to 1. Therefore, since variation in the differential signal detected by detection unit 25 can be suppressed, it is possible to stabilize the performance of sensor unit 23 at low cost without performing calibration or the like for each steering wheel 1 individually.

[0035] In particular, by making the capacitance Csg2 of the capacitive element 45 larger than the capacitance Csg1 structurally generated between the shield electrode 26 and the core 10, the variation in the capacitance Csg, which is the combined capacitance of these, can be more reliably suppressed.

[0036] Therefore, the accuracy of detecting the state of grip of the rim portion 3 by the user can be improved, which also contributes to improving the accuracy of automatic driving based on the detection of the grip state. [Industrial Applicability]

[0037] The present invention can be suitably used as a steering wheel for a vehicle such as an automobile. [Explanation of symbols]

[0038] 1 handle 3 Rim part that serves as the gripping part 10 Core 13 Rim core metal part which is the core metal part of the grip part 15 Covering part 23 Sensor section 24 Sensor body 25 Detector 26 Shield electrode 27 Sensor electrode 28 Dielectrics, which are insulators 45 Capacitor element 46 Wiring GND reference potential

Claims

1. a core metal electrically connected to a reference potential; a covering portion that covers a part of the core metal; a sensor unit including a sensor body portion including a shield electrode, a sensor electrode, and an insulator interposed between the shield electrode and the sensor electrode, the sensor body portion being disposed in the covering portion with the shield electrode on the core metal side, and a detection portion electrically connected to the shield electrode and the sensor electrode; a wiring connected to the capacitance element, electrically connecting the shield electrode and the core metal, and capable of being charged between the shield electrode and the core metal; A handle comprising:

2. The capacitance of the capacitive element is larger than the capacitance generated structurally between the shield electrode and the core metal.

2. The handle of claim 1.

3. A grip portion to be gripped by a user is provided, the core metal has a grip portion core metal portion that forms a core of the grip portion, the covering portion covers at least the grip portion core metal portion, The sensor unit is a capacitance sensor that detects the state of gripping of the grip unit by the user based on a change in capacitance.

3. The handle according to claim 1 or 2.

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