Vehicle speed sensor

Abstract

To provide a vehicle speed sensor capable of reducing idling caused by wear of a drive shaft.SOLUTION: The insertion key 2 is connected to the transmission of the vehicle and rotates in accordance with the rotation of the transmission. The drive shaft 3 is provided with a bearing hole 31 into which the tip of the insertion key 2 is inserted, and rotates according to the rotation of the insertion key 2. The rotating magnet 4 is attached to the drive shaft 3 and rotates in accordance with the rotation of the drive shaft 3. A Hall IC mounted on the wiring board 5 detects the rotation of the rotating magnet 4 to detect the vehicle speed. The tip of the insertion key 2 and the bearing hole 31 of the driving shaft 3 are provided in a hexagonal cross section.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vehicle speed sensor. [Background technology]

[0002] A conventional vehicle speed sensor is disclosed in Patent Document 1. The vehicle speed sensor disclosed in Patent Document 1 transmits the rotation of the transmission to a drive shaft (second rotation shaft) via an insert key (first rotation shaft). A magnet (rotating part) that rotates together with the drive shaft is attached to the drive shaft. A Hall IC detects the rotation of the magnet to detect the vehicle speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-221356 Summary of the Invention [Problem to be solved by the invention]

[0004] The drive shaft is provided with a bearing hole into which the tip of the bayonet key is inserted. Conventionally, the tip of the drive shaft and the bearing hole have been provided with a square cross section, as shown in Figure 5. This has led to the problem that the corners of the bayonet key can wear out the bearing hole of the drive shaft, causing it to spin freely.

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a vehicle speed sensor that can reduce spinning caused by wear of the second rotating shaft portion. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the vehicle speed sensor according to the present invention has the following features. a first rotating shaft portion connected to a transmission of a vehicle and rotating in response to rotation of the transmission; a second rotating shaft portion provided with a bearing hole into which a tip end of the first rotating shaft portion is inserted and which rotates in response to rotation of the first rotating shaft portion; a rotating part attached to the second rotating shaft part and rotating in response to rotation of the second rotating shaft part; a sensor unit that detects the rotation of the rotating unit and detects the vehicle speed. In the vehicle speed sensor, The tip of the first rotating shaft portion and the bearing hole of the second rotating shaft portion are provided with a cross section having a pentagonal or larger shape. It is a vehicle speed sensor. [Effects of the Invention]

[0007] The vehicle speed sensor according to the present invention has the effect of reducing spinning caused by wear of the second rotating shaft portion.

[0008] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of a vehicle speed sensor of the present invention. [Figure 2] FIG. 2 is a perspective view of the bayonet key shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the drive shaft shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the bayonet key and the drive shaft shown in FIG. 1 taken along line AA. [Figure 5] FIG. 5 is a cross-sectional view of an insertion key and a drive shaft in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0011] 1, the vehicle speed sensor 1 includes an insertion key 2 as a first rotating shaft, a drive shaft 3 as a second rotating shaft, a rotating magnet 4 as a rotating part, a wiring board 5, a storage case 6, terminals 7, and a connector housing 8. The insertion key 2 is connected to the vehicle's transmission and rotates in accordance with the rotation of the transmission.

[0012] As shown in Figure 2, the insertion key 2 has a large diameter portion 21 with a large cross-sectional area located on the lower side (away from the drive shaft 3) in the axial direction, and a small diameter portion 22 with a small cross-sectional area located on the upper side (closer to the drive shaft 3) in the axial direction. The large diameter portion 21 has a circular cross section. A key 23 that meshes with a driven gear of the transmission protrudes from the outer surface of the large diameter portion 21. In this embodiment, the small diameter portion 22 has a regular hexagonal cross section.

[0013] As shown in FIG. 3, the drive shaft 3 is provided with a bearing hole 31 into which the tip of the small diameter portion 22 of the insertion key 2 is inserted. The bearing hole 31 is provided to penetrate the drive shaft 3 in the axial direction. From bottom to top, the bearing hole 31 is provided with a large diameter hole 31A, a fitting hole 31B, a large diameter hole 31C, and a small diameter hole 31D. The large diameter hole 31A is provided at the lower end of the bearing hole 31 and is circular, larger than the fitting hole 31B but smaller than the large diameter portion 21 of the insertion key 2. The fitting hole 31B communicates with the upper side of the large diameter hole 31A and, as shown in FIG. 4, is regular hexagonal so that the small diameter portion 22 of the insertion key 2 can be fitted into it.

[0014] Large diameter hole 31C communicates with the upper side of fitting hole 31B and is circular and of the same size as large diameter hole 31A. Small diameter hole 31D is provided at the upper end of bearing hole 31 and communicates with the upper side of large diameter hole 31C. Small diameter hole 31D is circular and smaller than large diameter holes 31A and 31C.

[0015] As shown in FIG. 1, the rotary magnet 4 is attached to the upper end of the drive shaft 3 and rotates in response to the rotation of the drive shaft 3. In this embodiment, the rotary magnet 4 has a disk portion 41 and a magnet main body 42. The disk portion 41 is disk-shaped, and the upper end of the drive shaft 3 is inserted into the center. The magnet main body 42 is disposed on the disk portion 41. The magnet main body 42 is ring-shaped, with the center of the disk portion 41 as its center. The magnet main body 42 has alternating north and south poles arranged along the ring.

[0016] A Hall IC (sensor unit) that detects the rotation of the rotating magnet 4 and detects the vehicle speed is mounted on the wiring board 5. In this embodiment, the wiring board 5 is provided in a disk shape. The wiring board 5 is disposed above the rotating magnet 4 and is disposed opposite to the rotating magnet 4 in the axial direction.

[0017] The storage case 6 is cylindrical and stores the above-mentioned insertion key 2, drive shaft 3, rotary magnet 4, and wiring board 5. The end of the insertion key 2 protrudes from the opening on the bottom side of the storage case 6.

[0018] One end of the terminal 7 is connected to the wiring board 5, and the other end protrudes upward. The connector housing 8 is cylindrical, and the lower side is fitted into the accommodating case 6. The connector housing 8 accommodates the tip of the terminal 7.

[0019] Next, the effects of the above-described embodiment will be described in comparison with a comparative example shown in FIG. 5. In the comparative example shown in FIG. 5, the bearing holes 310 of the insertion key 200 and drive shaft 300 have a square cross section. In the comparative example, the four corners of the insertion key 200 abut against the inner surface of the bearing hole 310. In contrast, according to this embodiment, the tip (small diameter portion 22) of the insertion key 2 has a hexagonal cross section, and the bearing hole 31 of the drive shaft 3 also has a hexagonal cross section. As shown in FIG. 4, when the insertion key 2 rotates, six corners of the insertion key 2 abut against the inner surface of the bearing hole 31. This increases the number of corners compared to the insertion key 200 of the comparative example, which has a square cross section. As a result, the force at the corners of the insertion key 2 is dispersed, reducing wear on the bearing hole 31 due to the corners and reducing idling caused by wear on the drive shaft 3.

[0020] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. Furthermore, the material, shape, size, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0021] In the above-described embodiment, an example has been described in which the rotating magnet 4 is used as the rotating part, but the present invention is not limited to this. For example, the rotation speed may be optically detected by providing a slit or a light source in the disk part 41.

[0022] In the above-described embodiment, the insertion key 2 and the bearing hole 31 of the drive shaft 3 are provided with a hexagonal cross section, but this is not limited to this. The insertion key 2 and the bearing hole 31 may be pentagonal or heptagonal or more as long as they have a pentagonal or more polygonal shape. It is more preferable that the insertion key 2 and the bearing hole 31 have an octagonal or less polygonal shape.

[0023] Here, the features of the above-described embodiments of the vehicle speed sensor according to the present invention will be briefly summarized and listed below in [1].

[0024] [1] a first rotating shaft portion (2) connected to a transmission of a vehicle and rotating in response to rotation of the transmission; a second rotating shaft portion (3) provided with a bearing hole (31) into which the tip of the first rotating shaft portion (2) is inserted and which rotates in response to the rotation of the first rotating shaft portion (2); a rotating part (4) attached to the second rotating shaft part (3) and rotating in response to rotation of the second rotating shaft part (3); a sensor unit (5) that detects the rotation of the rotating unit (4) and detects the vehicle speed; In the vehicle speed sensor (1), The tip of the first rotating shaft portion (2) and the bearing hole (31) of the second rotating shaft portion (3) are provided with a cross section having a pentagonal or greater shape. Vehicle speed sensor (1).

[0025] According to the vehicle speed sensor (1) having the configuration [1] above, the force at the corners of the first rotating shaft portion (2) is dispersed, which reduces wear on the bearing hole (31) of the second rotating shaft portion (3) due to the corners, thereby reducing spinning caused by wear on the second rotating shaft portion (3). [Explanation of symbols]

[0026] 1 Vehicle speed sensor 2 Insertion key (first rotating shaft) 3 Drive shaft (second rotating shaft) 4 Rotating magnet (rotating part) 5. Wiring board (sensor section) 31 Bearing hole

Claims

[Claim 1] a first rotating shaft portion connected to a transmission of a vehicle and rotating in response to rotation of the transmission; a second rotating shaft portion having a bearing hole into which a tip end of the first rotating shaft portion is inserted and which rotates in response to rotation of the first rotating shaft portion; a rotating part attached to the second rotating shaft part and rotating in response to rotation of the second rotating shaft part; a sensor unit that detects the rotation of the rotating unit and detects the vehicle speed. In the vehicle speed sensor, The tip of the first rotating shaft portion and the bearing hole of the second rotating shaft portion are provided with a cross section having a pentagonal or larger shape. Vehicle speed sensor.

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