Flood sensor and turning device

Abstract

To provide a flood sensor which suppresses an entry of water into a processing device like a control device, and which can detect the presence or absence of flooding at a portion subjected to a detection.SOLUTION: A PU 80 and a humidity sensing unit 82 are mounted on a substrate 70. The humidity sensing unit 82 is configured to sense the surrounding humidity, and to output the sensing result to the PU 80. The humidity sensing unit 82 faces a porous member 84 via an air gap GA. The porous member 84 is formed in an L-shape. The porous member 84 has an opposite end to an end facing the humidity sensing unit 82 in the pair of ends, the opposite end extending in a negative z-axis direction. Such an opposite end is located at the lowest position in the vertical direction in a casing where a motor is stored.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a water ingress sensor and a steering device. [Background technology]

[0002] Patent Document 1 listed below describes a device for detecting flooding of a steering device (electric power steering device). This device is configured by connecting a detection wire, one end of which extends into a water collection area, to a wire connected to the terminal of a motor of the steering device, and by connecting a connection wire, one end of which extends into the water collection area, to a control device. As a result, if the water collection area is flooded, the control device can detect a change in the potential of the wire connected to the terminal of the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-507812 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of the above-described device, there is a risk that water that has flowed along the detection lead wire or the connection lead wire may come into contact with the control device, causing an abnormality in the control device. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. 1. A water-immersion sensor comprising a water-absorbing member, a humidity sensing unit, and a determination unit, wherein the water-absorbing member extends from the area to be detected for water immersion to the humidity sensing unit and absorbs water from the area to be detected, the humidity sensing unit senses humidity in the vicinity of the humidity sensing unit, and the determination unit is configured to determine whether the area to be detected is flooded or not based on the sensing result of the humidity sensing unit.

[0006] If water is present in the detection target location, the water is absorbed by the water-absorbing member. The water absorbed by the water-absorbing member is guided to the vicinity of the humidity sensor while being retained inside the water-absorbing member. Therefore, when water is present in the detection target location, the humidity sensor detects a higher humidity level than when there is no water. Therefore, the determination unit can determine whether the detection target location is flooded with water based on the detection result of the humidity sensor. Therefore, the determination unit can determine whether the detection target location is flooded with water without directly coming into contact with water.

[0007] 2. The water immersion sensor according to claim 1, wherein the water-absorbing member is a porous member. In the above configuration, since the water-absorbing member is a porous member, it is possible to utilize capillary action to guide water from the detection target location to the vicinity of the humidity sensing portion.

[0008] 3. The water immersion sensor according to claim 1 or 2, wherein an air gap is provided between the end of the water absorbing member and the humidity sensing portion. In the above configuration, by providing an air gap between the humidity sensor and the water absorbing member, it is possible to prevent water from entering the determination unit via the humidity sensor.

[0009] 4. A steering device comprising a flood sensor described in any one of 1 to 3 above and a motor unit, wherein the motor unit contains a steering motor that steers steered wheels and a control device for the steering motor within a housing, and the detection target location is a location vertically below the space in the motor unit in which the control device is contained.

[0010] In the above configuration, since the detection target location is a location vertically downward within the housing, if water enters the housing, the intrusion of water into the housing can be detected before the water reaches the control device. 5. A steering device as described in 4 above, comprising a steering shaft and a gear assembly, wherein the steering shaft is configured to steer the steered wheels by displacing it in the axial direction, the rotation axis of the steering motor is arranged parallel to the axial direction of the steering shaft, and the gear assembly is configured to convert the rotational power of the steering motor into axial displacement of the steering shaft.

[0011] In the above configuration, the housing is located closer to the road surface than when, for example, the torque of the steering motor is applied to a position on the steering shaft closer to the steering wheel. Therefore, there is a greater risk of water entering the housing than when the torque of the steering motor is applied to a position on the steering shaft closer to the steering wheel. Therefore, there is particularly great value in setting a predetermined location inside the housing as the detection target location. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic configuration of an electric power steering device; [Figure 2] 2 is a cross-sectional view showing the cross-sectional configuration of a motor unit provided in the electric power steering device shown in FIG. 1. [Figure 3] 3 is an enlarged cross-sectional view of a part of the motor unit shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment will be described with reference to the drawings. "Overall structure" As shown in FIG. 1, the electric power steering device 10 includes a steering mechanism 20 that steers steered wheels 14 based on the operation of a steering wheel 12 by a driver, and an assist device 40 that assists the steering operation of the driver.

[0014] The steering mechanism 20 includes the steering wheel 12 and a steering shaft 22 that rotates integrally with the steering wheel 12. The lower end of the steering shaft 22 is connected to a rack shaft 26 via a rack-and-pinion mechanism 24. Therefore, in the steering mechanism 20, the rotational motion of the steering shaft 22 is converted into reciprocating linear motion in the axial direction of the rack shaft 26 (the left-right direction in FIG. 1 ) via the rack-and-pinion mechanism 24. This reciprocating linear motion is transmitted to tie rods 30 via rack ends 28 that are connected to both ends of the rack shaft 26, respectively. The motion of these tie rods 30 is transmitted to the left and right steered wheels 14, respectively, thereby changing the steering angle of the steered wheels 14.

[0015] The assist device 40 is provided on the rack shaft 26. The assist device 40 is made up of a motor unit 50, a ball screw mechanism 42 integrally attached around the rack shaft 26, and a reducer 44 that transmits the rotational force of a rotating shaft 66 of a motor 60 provided in the motor unit 50 to the ball screw mechanism 42. The assist device 40 converts the rotational force of the rotating shaft 66 of the motor 60 into a force applied in the axial direction of the rack shaft 26 via the reducer 44 and the ball screw mechanism 42. This axial force applied to the rack shaft 26 becomes an assist force, thereby assisting the steering operation of the driver.

[0016] The ball screw mechanism 42, the reducer 44, a portion of the steering shaft 22, and the rack shaft 26 are covered by a housing 32. The housing 32 has an insertion portion 34a through which the rack shaft 26 is inserted. The housing 32 has a reducer housing 34b that protrudes in a direction intersecting the direction in which the rack shaft 26 extends (downward in the figure). A portion of the reducer 44 is accommodated inside the reducer housing 34b. A through-hole 34c is formed in the outer wall (the right wall in the figure) of the reducer housing 34b. The rotating shaft 66 of the motor 60 extends into the reducer housing 34b through the through-hole 34c formed in the reducer housing 34b. The motor unit 50 is fixed to the reducer housing 34b with bolts 51 so that the rotating shaft 66 of the motor 60 is parallel to the rack shaft 26. A small gap S1 is provided between the insertion portion 34a and the rack shaft 26.

[0017] A bellows-shaped rack boot 34 is disposed at each end of the housing 32 (insertion portion 34a). One end of the rack boot 34 is connected to an end of the housing 32, and the other end of the rack boot 34 is connected to the tie rod 30. The housing 32 and the rack end 28 are covered by the corresponding rack boot 34. Each rack boot 34 prevents foreign matter such as water and dust from entering the housing 32 and the rack end 28.

[0018] "Motor Unit 50" FIG. 2 shows a cross-sectional configuration of the motor unit 50. 2 includes a motor housing 52 and a cover 54 as a housing. A motor 60 and a control unit are housed in a packaged state within the space defined by the motor housing 52 and the cover 54.

[0019] A motor 60 is housed in the space defined by the motor housing 52 of the motor unit 50. The motor 60 includes a stator 62, a rotor 64, and a rotary shaft 66.

[0020] In Fig. 2, the axial direction of the rotation shaft 66 is the x-axis direction. Therefore, the radial direction of the rotor 64 is a direction perpendicular to the x-axis. In other words, the radial direction of the rotor 64 is expressed by the sum of a vector in the y-axis direction and a vector in the z-axis direction. Note that the x-axis, y-axis, and z-axis are depicted in Fig. 1 to be consistent with Fig. 2.

[0021] The motor housing 52 has a peripheral wall (side wall 56) that forms the outer periphery. The motor housing 52 is open at the other end of the side wall 56. In other words, the motor housing 52 is open in the positive direction of the x-axis in FIG. 1. The opening of the motor housing 52 is closed by a bearing holder 58. The bearing holder 58 is generally plate-shaped.

[0022] The bearing holder 58 has a first surface and a second surface that face opposite to each other in the x-axis direction. The first surface faces the stator 62 and the rotor 64 in the x-axis direction. The second surface is a control side that faces the substrate 70. The substrate 70 is fixed to the motor housing 52 with bolts 72.

[0023] A drive circuit and a control circuit that constitute a control unit are mounted on the substrate 70. The drive circuit is a circuit that drives the motor 60. The drive circuit includes an inverter and the like. The control circuit is a circuit that controls the torque of the motor 60 by operating the drive circuit.

[0024] "Water ingress sensor" FIG. 3 shows an enlarged view of a portion near the substrate 70. As shown in FIG. 3, a PU 80 and a humidity sensor 82 are mounted on the substrate 70. The PU 80 is a processing unit that executes software processing. The PU 80 operates a drive circuit to control the torque of the motor 60. The PU 80 may be composed of at least one of a CPU, a GPU, etc., for example. The humidity sensor 82 is configured to sense the ambient humidity and output the sensing result to the PU 80.

[0025] The humidity sensor 82 faces the porous member 84 via an air gap GA. The porous member 84 is formed, for example, from a sponge. The porous member 84 is an L-shaped member. One of a pair of ends of the porous member 84, the end opposite the end facing the humidity sensor 82, extends in the negative z-axis direction. The opposite end is located at the vertically lowest position in the space on the cover 54 side of the internal space of the motor unit 50, which is divided into two by the bearing holder 58. In the space on the cover 54 side of the internal space of the motor unit 50, which is divided into two by the bearing holder 58, the vertically lowest region is the region where water first accumulates when water enters the motor unit 50. This region is set as a water detection target location DA.

[0026] The PU 80 receives the detection result signal output by the humidity sensor 82. Based on the detection result signal as an input signal, the PU 80 monitors whether water has entered the motor unit 50. If the humidity indicated by the detection result signal is equal to or greater than a threshold, the PU 80 determines that water has entered the motor unit 50. If the PU 80 determines that water has entered, the PU 80 notifies the user by operating a user interface (not shown). The user interface may be, for example, a speaker. In this case, the PU 80 may notify the user of the water intrusion by using an audio signal. Alternatively, the user interface may be a display device. In this case, the PU 80 may notify the user of the water intrusion by displaying visual information indicating the water intrusion on the display device.

[0027] "Actions and Effects of the Present Embodiment" When water enters the motor unit 50, the water accumulates in a detection target location DA, which is a vertically lower region of the internal space of the motor unit 50. An end of a porous member 84 is provided at the detection target location DA. The porous member 84 is formed so as to extend vertically upward and then bend to approach the humidity sensing unit 82.

[0028] When water accumulates at the detection target location DA, the porous member 84 absorbs the water. The water absorbed by the porous member 84 seeps into the end portion facing the humidity sensing unit 82 due to capillary action. The water that seeps into the porous member 84 near the end portion facing the humidity sensing unit 82 evaporates, increasing the humidity in the surrounding area. This increases the humidity near the air gap GA. When the humidity near the air gap GA increases, the humidity sensed by the humidity sensing unit 82 also increases. Therefore, the PU 80 determines that water has entered the motor unit 50 based on a comparison of the humidity indicated by the sensing result signal as an input signal with a threshold value. This makes it possible to determine whether water has entered the motor unit 50 without immersing the circuit board 70 in water.

[0029] According to the present embodiment described above, the following actions and effects can be further obtained. (1) The air gap GA is provided between the end of the porous member 84 and the humidity sensor 82, so that water can be prevented from entering the PU 80 via the humidity sensor 82.

[0030] (2) The location of water ingress detection, which is the location where water is absorbed by the porous member 84, is set to a location vertically downward within the space inside the housing of the motor unit 50. Therefore, if water infiltrates into the housing, the intrusion of water into the housing can be detected before the water reaches the control device.

[0031] (3) A configuration is adopted in which the rotating shaft 66 of the motor 60 is disposed parallel to the axial direction of the rack shaft 26. In this case, the motor unit 50 is disposed closer to the road surface than when the torque of the motor 60 is applied to a position on the steering shaft 22 closer to the steering wheel 12. Therefore, there is a greater risk of water entering the motor unit 50 than when the torque of the motor 60 is applied to a position on the steering shaft 22 closer to the steering wheel 12. Therefore, there is particularly great value in setting a predetermined location within the motor unit 50 as the detection target location DA.

[0032] <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the "Means for solving the problem" column is as follows. Below, the correspondence is shown for each number of the means for solving the problem described in the "Means for solving the problem" column. [1-3] The water-absorbing member corresponds to the porous member 84. The determination unit corresponds to the PU 80. The steering device corresponds to the electric power steering device 10. [4] The steering motor corresponds to the motor 60. The control device corresponds to the PU 80. [5] The gear assembly corresponds to the ball screw mechanism 42 and the reducer 44, and the steering shaft corresponds to the rack shaft 26.

[0033] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0034] "About water-absorbing materials" The shape of the porous member 84 is not limited to the example shown in Fig. 3. For example, it may be a rod-shaped member that does not have any bent portions.

[0035] The porous member 84 does not necessarily have to be a sponge. The porous member 84 may be, for example, charcoal. Also, for example, the porous member 84 may be porous ceramic.

[0036] The water-absorbing material is not limited to a porous material as long as it can absorb water. It is not essential to provide an air gap between the water absorbing member and the humidity sensor. "Detection target areas" The location to be detected for flooding is not limited to the location illustrated in FIG. 3 . For example, it may be a location that is vertically low in the space defined by the motor housing 52 and the bearing holder 58. The location to be detected for flooding is not limited to a predetermined location within the interior space of the motor unit 50. For example, it may be a predetermined location within the gear assembly housing space, such as the interior of the reducer housing 34b. In this case, the humidity sensor 82 may be provided within the gear assembly housing space, and the humidity sensor 82 may be connected to the PU 80 within the motor unit 50 by a signal line. Furthermore, for example, a determination unit that determines whether flooding has occurred may be formed by a component independent of the control device, and this component may be provided within the gear assembly housing space. Furthermore, for example, the detection location may be a predetermined location within a housing that houses a torque sensor that detects torque input to the steering wheel 12. In this case, the housing that houses the torque sensor may be a housing separate from the motor unit 50.

[0037] "About the steering device" The steering device is not limited to a device that can transmit power between the steering wheel 12 and the steered wheels 14. The steering device may be, for example, a steer-by-wire type device in which power transmission between the steering wheel 12 and the steered wheels 14 is blocked. [Explanation of symbols]

[0038] 10...Electric power steering device 12...Steering wheel 14...Steering wheel 22...Steering shaft 32…Housing 34...Rack boots 42...Ball screw mechanism 44...Reducer 50...Motor unit 51...Bolt 52...Motor housing 54...Cover 60...Motor 82...Humidity sensing section 84...Porous material

Claims

1. The device includes a water-absorbing member, a humidity sensor, and a determination unit, The water-absorbing member extends from the location to be detected for flooding to the humidity sensor and absorbs water from the location to be detected, the humidity sensor is a member that senses humidity in the vicinity of the humidity sensor, The determination unit is configured to determine whether the detection target location is flooded or not based on the detection result of the humidity detection unit.

2. 2. The water immersion sensor according to claim 1, wherein the water-absorbing member is a porous member.

3. 2. The water immersion sensor according to claim 1, wherein an air gap is provided between the end of said water absorbing member and said humidity sensing portion.

4. The water immersion sensor according to claim 1; a motor unit; The motor unit includes a steering motor for steering the steered wheels and a control device for the steering motor housed in a housing, The detection target location is a steering device that is a location vertically below the space in the motor unit in which the control device is housed.

5. Equipped with a steering shaft and gear assembly, The steering shaft is configured to steer the steered wheels by being displaced in an axial direction, a rotation axis of the steering motor is arranged parallel to the axial direction of the steering shaft, 5. The steering device according to claim 4, wherein the gear assembly is configured to convert the rotational power of the steering motor into an axial displacement of the steering shaft.

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