JP6700147B2 - Power steering device - Google Patents

Description

  The present invention relates to a power steering device.

  As an electric power steering apparatus including a moisture detection sensor, for example, an electric power steering apparatus described in Patent Document 1 below is known.

  In this electric power steering device, moisture detection sensors are provided in boots located at both axial ends of the rack bar housing.

JP 2012-224274 A

  In Patent Document 1, a moisture detection sensor that detects the infiltration of moisture into the boot is provided, but there is no function to determine the failure of the moisture detection sensor, and when the sensor fails, the infiltration of water causes electric power steering. There is a possibility that the device may malfunction.

  The present invention has been devised in view of the conventional circumstances, and an object of the present invention is to provide a power steering device that reduces defects of the electric power steering device due to infiltration of water.

  According to the present invention, in one aspect thereof, the power steering device includes a first abnormality determination unit that determines the presence or absence of moisture in the housing based on a change in voltage that is an output signal of the moisture detection circuit, and the moisture detection circuit. And a second abnormality determination unit that determines whether or not there is an abnormality.

  ADVANTAGE OF THE INVENTION According to this invention, the malfunction of the power steering apparatus by the infiltration of water reduces.

It is a front view showing the electric power steering device concerning the 1st example of the present invention. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is a longitudinal cross-sectional view which cuts and shows the internal structure of the electric motor and ECU which concern on a 1st Example along a perpendicular direction. It is a longitudinal cross-sectional view showing the stator of the electric motor according to the first embodiment. It is an expanded sectional view which expands and shows the instruction line C part of FIG. It is a perspective view which shows the water|moisture content sensor of 1st Example, a grommet, and a water receiving part. It is a block diagram which shows the outline of the water|moisture content detection process and abnormality determination process by the control circuit of a 1st Example. FIG. 3 is a schematic electric circuit diagram of a moisture detection circuit at a normal time in the first embodiment. It is a schematic electric circuit diagram of the moisture detection circuit at the time of moisture penetration in the first embodiment. It is explanatory drawing which showed the voltage applied to the A/D converter before and after water infiltration. It is a schematic electric circuit diagram of the moisture detection circuit of the first embodiment. It is explanatory drawing of the initial diagnosis of the moisture detection circuit of 1st Example. It is a schematic electric circuit diagram of the moisture detection circuit of a 2nd Example. It is explanatory drawing of the initial diagnosis of the moisture detection circuit of 2nd Example. It is a schematic electric circuit diagram of the water|moisture content detection circuit of 3rd Example.

An embodiment of the power steering device according to the present invention will be described below in detail with reference to the drawings.
[First Embodiment]
(Structure of power steering device)
FIG. 1 is a front view showing an electric power steering device 1.

  As shown in FIG. 1, the electric power steering device 1 includes a steering mechanism 2 that transmits a steering force from a driver and a steering assist mechanism 3 that assists the driver's steering operation. At least a part of the steering mechanism 2 and the steering assist mechanism 3 is housed in a housing member 4 made of metal such as aluminum.

  The housing member 4 corresponds to the "housing" described in the claims.

  The steering mechanism 2 mechanically connects a steering wheel (not shown) arranged in a driver's cab of the vehicle and two steered wheels (not shown) which are front wheels of the vehicle. The steering mechanism 2 includes a steering shaft 7 having an input shaft 5 to which the rotational force from the steering wheel is transmitted and an output shaft 6 connected to the input shaft 5 via a torsion bar (not shown), and a steering shaft 7. A conversion mechanism 8 for converting the rotation of the steering shaft 7 into a linear motion is provided. The conversion mechanism 8 is a rack-and-pinion mechanism including pinion teeth 6a (see FIG. 2) formed on the outer circumference of the output shaft 6 and rack teeth 9a (see FIG. 2) formed on the outer circumference of the rack bar 9. It is configured. Both ends of the rack bar 9 are connected to corresponding steered wheels via tie rods and knuckle arms (not shown).

  At the axial ends of the rack bar housing portion 10 for housing the rack bar 9, bellows-shaped boots 11, 11 that cover the outer peripheries of one end side of two tie rods (not shown) are installed. The boots 11 and 11 are made of an elastic material such as a synthetic rubber material so as to ensure a predetermined flexibility, and prevent water and dust from entering the rack bar 9 and the like.

  Further, mount brackets 12 for mounting the rack bar accommodating portion 10 to the vehicle body are provided at both ends of the rack bar accommodating portion 10 in the axial direction. A rubber bush (not shown) is installed on the mount bracket 12, and the rack bar accommodating portion 10 is attached to the vehicle body via the rubber bush.

  The steering assist mechanism 3 includes an electric motor 13 that applies a steering assist force to the steering mechanism 2, a control device (ECU) 14 that drives and controls the electric motor 13, and a worm gear 15 that is a speed reducer (transmission mechanism). I have it. The electric motor 13 is configured integrally with the control device 14. The electric motor 13 is housed in the motor housing portion 16. The worm gear 15 transmits the steering assist force (rotational force) output by the electric motor 13 to the output shaft 6 while decelerating it.

  With the configuration of the electric power steering device 1, when the driver rotationally operates the steering wheel, the input shaft 5 rotates and the torsion bar is twisted, and the elastic force of the torsion bar causes the output shaft 6 to rotate. Then, the rotational movement of the output shaft 6 is converted into a linear movement along the axial direction of the rack bar 9 by the rack and pinion mechanism, and a knuckle arm (not shown) is also moved in the vehicle width direction via two tie rods (not shown). By being pulled, the orientation of the corresponding steered wheels is changed.

  FIG. 2 is a cross-sectional view of the rack bar 9 and the like cut along the line AA of FIG.

  As shown in FIG. 2, the elongated cylindrical rack bar housing portion 10 is formed so as to communicate with the worm wheel housing portion 17 inside. As a result, the housing member 4 is configured so that the rack bar housing portion 10, the speed reducer housing portion 18, and a motor ECU housing portion 19 (see FIG. 3) described later that configure the housing member 4 all communicate with each other through the internal space. It has become.

  Further, the rack teeth 9a formed on the outer circumference of the rack bar 9 in the rack bar housing portion 10 and the pinion teeth 6a formed on the outer circumference of the output shaft 6 in the reduction gear housing portion 18 mesh with each other, This constitutes the rack and pinion mechanism. The rack bar accommodating portion 10 includes a rack retainer accommodating portion 20 that projects from the rack bar accommodating portion 10 in a cylindrical shape so as to be orthogonal to the rack bar 9. A rack retainer 21, a spring 22 that urges the rack bar 9 toward the output shaft 6, and a closed-end cylindrical closing member 23 that supports the spring 22 are provided in the rack retainer housing portion 20. There is. By biasing the rack bar 9 toward the output shaft 6 by the spring 22 and the rack retainer 21, backlash between the rack teeth 9a on the outer periphery of the rack bar 9 and the pinion teeth 6a on the outer periphery of the output shaft 6 is suppressed. There is.

  FIG. 3 is a cross-sectional view of the motor ECU housing portion 19 and the like taken along the line BB of FIG.

  As shown in FIG. 3, the electric motor 13 is a so-called three-phase induction motor driven based on a three-phase alternating current. The electric motor 13 includes a motor housing portion 16 that constitutes a part of the housing member 4, a stator 24 and a rotor 25 provided in the motor housing portion 16, and a drive shaft 26 that rotates integrally with the rotation of the rotor 25. And are equipped with.

  The motor housing portion 16 has a substantially cylindrical tubular portion 27 that accommodates the stator 24 and the rotor 25 therein, and one side wall 28 that is a wall portion that closes one end opening of the tubular portion 27 on the worm gear 15 side. It is mainly configured by a partition wall 29 provided at a substantially central position in the axial direction of the drive shaft 26 of the tubular portion 27.

  The cylindrical portion 27 is formed such that the outer diameter of the one end portion 27a is smaller than that of the other portion, and the one end portion 27a is fitted in the opening portion of the worm shaft accommodating portion 30 of the worm gear 15 to be described later. And is fixed to the opening with a bolt 31 (see FIG. 1).

  Further, the tubular portion 27 is configured such that a portion on the other end side of the partition wall 29 in the axial direction of the drive shaft 26 constitutes a part of an ECU housing portion 32 of the ECU 14 which will be described later. That is, the motor housing portion 16 and the ECU housing portion 32 are integrally configured as the motor ECU housing portion 19 by sharing the tubular portion 27.

  The one side wall 28 is formed in a substantially disk shape, is fixed to the end surface of the tubular portion 27 on the one end portion 27a side by a bolt 33, and is disposed at a substantially central position on the worm gear 15 side in the axial direction of the drive shaft 26. A circular recessed wall portion recessed portion 28a is formed so as to open toward the side.

  A first insertion hole 28b into which one end 26a of the drive shaft 26 is inserted is formed at the center of the one side wall 28, and the end face on the rotor 25 side has a substantially cylindrical first bearing accommodating portion. 28c is formed to project. A first ball bearing 34 is housed in the first bearing housing 28c, and one end 26a of the drive shaft 26 is rotatably supported via the first ball bearing 34.

  The partition wall 29 is formed in a substantially disk shape and is fixed to the inner periphery of the tubular portion 27, and a second insertion hole 29a into which the other end portion 26b of the drive shaft 26 is inserted is formed at the central position thereof. Has been done. Further, the partition wall 29 has a substantially cylindrical second bearing accommodating portion 29b protrudingly formed on the end surface on the rotor 25 side. A second ball bearing 35 is housed in the second bearing housing portion 29b, and the other end portion 26b of the drive shaft 26 is rotatably supported via the second ball bearing 35.

  The ECU 14 is housed in an ECU housing portion 32 that forms a part of the housing member 4 and a control circuit housing portion 32 a formed inside the ECU housing portion 32, and is used for drive control of the electric motor 13 and the like. And a circuit 36.

  The ECU housing portion 32 closes the tubular portion 27 and the partition wall 29 that are also a part of the motor housing portion 16, the cylindrical casing member 37, and the open end of the casing member 37 on the opposite side of the tubular portion 27. The cover member 38 is mainly included. The casing member 37 is fixed to the open end of the tubular portion 27 on the other end portion 27b side by a bolt 39 (see FIG. 1). The cover member 38 is fixed to the opening end of the casing member 37 on the side opposite to the tubular portion 27 by a bolt 40 (see FIG. 1). The ECU housing portion 32 is adapted to communicate with the motor housing portion 16 inside via the second insertion hole 29 a of the partition wall 29.

  The control circuit 36 is composed of a circuit board, a microcomputer, and the like, and includes a power module 41 and a control module 42. The power module 41 generates three-phase AC power supplied to the electric motor 13 based on the power supplied from a battery (not shown) mounted on the vehicle. The control module 42 drives and controls a switching element (not shown) represented by a MOS-FET in the power module 41.

  As shown in FIG. 3, the worm gear 15 is fixed to one end 26 a of the drive shaft 26 of the electric motor 13 via a shaft coupling 43 so as to be integrally rotatable, and to the lower end of the output shaft 6. And a worm wheel 45 made of synthetic resin. A tooth portion 44 a is formed on the outer circumference of the worm shaft 44. Further, a tooth portion 45 a that meshes with the tooth portion 44 a of the worm shaft 44 is formed on the outer periphery of the worm wheel 45.

  The speed reducer accommodating portion 18 has a substantially bottomed cylindrical worm shaft accommodating portion 30 that accommodates the worm shaft 44 therein, and a flat cylindrical shape that communicates with the worm shaft accommodating portion 30 and accommodates the worm wheel 45 therein. The worm wheel accommodating portion 17 and the worm wheel accommodating portion 17. Further, the speed reducer housing portion 18 communicates with the motor ECU housing portion 19 connected to the worm shaft housing portion 30 via the first insertion hole 28b of the one side wall 28.

  FIG. 4 is a vertical cross-sectional view showing the internal structures of the electric motor 13 and the ECU 14 taken along the rotational axis of the motor.

  A through hole 28d, into which first and second electrodes 47 and 48 of a moisture detection sensor 46 to be described later are inserted, is formed through the side wall 28 along the axial direction of the drive shaft 26.

  The through hole 28d is formed to have a substantially oval cross section, and is formed at the lower end in the vertical direction of the wall recess 28a, which is vertically lower than the first ball bearing 34 and the second ball bearing 35 of the one side wall 28. The grommet 49, which is arranged and is made of a resin material or a rubber material, has a flat elliptical cylindrical shape that liquid-tightly seals between the first and second electrodes 47, 48 and the through hole 28d. Is provided.

  The power module 41 is attached to the inner end surface of the cover member 38 of the ECU housing portion 32 that functions as a heat sink. The power module 41 also has three current output terminals (not shown) for outputting the three-phase AC power generated by the power module 41 on its substrate. One end of each of the three bus bars 50u, 50v, 50w forming a part of the control circuit 36 is connected to each current output terminal.

  Each of the bus bars 50u, 50v, 50w is in-molded in a resin-made bus bar mold member 51 disposed adjacent to the end surface of the partition wall 29 on the ECU housing portion 32 side. The other ends of the bus bars 50u, 50v, 50w are connected to the corresponding coils 52 (see FIG. 5) of the electric motor 13 via the relay terminals (not shown), and are generated by the power module 41. The phase AC power is supplied to the electric motor 13.

  The control module 42 forms a conductor pattern (not shown) on each of the front and back surfaces of a substrate 53 made of a non-conductive resin material typified by a glass epoxy resin. It is configured by mounting parts. The control module 42 is arranged at a position closer to the electric motor 13 than the power module 41 in the ECU housing portion 32.

  The microcomputer 54 performs various processes such as a calculation process of a motor command signal for controlling the electric motor 13 and a fail-safe process when an abnormality occurs in the electric power steering device 1.

  A moisture detection sensor 46 is provided inside the housing member 4 to detect moisture when it enters the housing member 4.

  The moisture detection sensor 46 detects the infiltration of moisture into the housing member 4 based on the detection of moisture in the worm shaft accommodating portion 30. The moisture detection sensor 46 is made of a conductive material and is formed into a pair of substantially cylindrical rods. It is mainly composed of the first and second electrodes 47 and 48.

  Most of the first and second electrodes 47 and 48 are housed in the motor ECU housing portion 19, and one end portion on the ECU 14 side is electrically connected to the control circuit 36. On the other hand, the other end penetrates the through hole 28d formed in the one side wall 28 and projects into the worm shaft housing portion 30, and each of the projecting portions is used for moisture detection. It functions as 55 and 56. A water receiving portion 57 that holds the moisture that has entered the worm shaft housing portion 30 is provided below the first and second moisture detecting portions 55 and 56 in the vertical direction.

  Further, the first and second electrodes 47, 48 are formed so as to extend from the respective moisture detectors 55, 56 into the motor ECU housing portion 19 via the through holes 28d, and are electrically connected to the control circuit 36. As a result, first and second transmission units 58 and 59 for transmitting electric signals between the control circuit 36 and the moisture detection units 55 and 56 are provided. The first and second transmission parts 58 and 59 are formed so as to extend from the first and second moisture detection parts 55 and 56 through the inside of the motor housing part 16 to the control circuit housing part 32a while being bent appropriately. There is. In the first and second transmission portions 58 and 59, the portions in contact with the busbar mold member 51 are provided in the first and second transmission portion holding holes 51a and 51b which are the transmission portion holding portions integrally formed with the busbar mold member 51. It is in-molded. Further, the first and second transmission portions 58 and 59 are covered with an insulating material 60 in the outer peripheral portions of the range provided in the motor housing portion 16.

  The first and second transmission parts 58 and 59 have respective one ends extending in the control circuit housing part 32a along connector shafts 61a and 61b provided on the substrate 53 of the control circuit 36 along the axial direction of the drive shaft 26. It is held by the control circuit 36 and electrically connected by being inserted.

  Here, the control circuit 36 outputs an electric signal to one of the moisture detectors 55 and 56 at all times or at regular intervals, and at the same time monitors the other moisture detector to detect the other moisture. When the electric signal is input from the detection unit, it is determined that water has entered the inside of the housing member 4. For example, after the boot 11 is damaged and water enters the inside of the housing member 4 from the damaged portion, the water reaches the worm shaft accommodating portion 30 and drops into the water receiving portion 57. Normally, the two moisture detectors 55 and 56, which are normally kept in a non-conducting state by being separated from each other, are in a moisture detecting state in which they are conducted through moisture, and the control circuit 36 transfers them to the first moisture detector 55 via the first transmitter 58. The output electric signal is input to the control circuit 36 from the second moisture detector 56 via the second transmitter 59. The control circuit 36 determines that the water has entered the inside of the housing member 4 by the input of the electric signal from the second moisture detector 56.

  The first and second electrodes 47 and 48 correspond to the "first terminal portion" and the "second terminal portion" described in the claims, respectively.

  FIG. 5 is a vertical cross-sectional view showing the stator 24 of the electric motor 13.

  The stator 24 includes a cylindrical stator core (not shown) formed of a magnetic material and a coil 52 wound around the stator core. The stator core is a substantially T-shaped split core 62 shown in FIG. Are formed in a circular ring shape.

  The split core 62 is formed by laminating a plurality of thin plates punched by a press. The split core 62 includes an arc-shaped core back 62a extending along the circumferential direction of the drive shaft 26, and teeth 62b protruding from the inner peripheral surface of the core back 62a. The coil 52 is wound. Further, a bobbin 63 formed of a non-conductive resin material is mounted on the portion of the split core 62 where the coil 52 abuts, that is, on the inner peripheral surface of the core back 62a and the outer surface of the tooth 62b. 52 is held in an electrically insulated state.

  Further, at a predetermined position on the outer peripheral surface of the core back 62a, a stator core recess 64 having a rectangular cross section is provided along the axial direction of the drive shaft 26.

  Further, the stator 24 is housed in the motor housing portion 16 in a state of being surrounded by a stator cover 65 formed of a metal material in a substantially cylindrical shape.

  As shown in FIG. 5, at least a part of the first and second transmission portions 58 and 59, which is substantially integrated with the stator 24, includes a stator core recess 64 and a stator cover 65 that form the electric motor 13. It is housed and arranged in between.

  FIG. 6 is an enlarged cross-sectional view showing an enlarged portion of the instruction line C in FIG.

  As shown in FIG. 6, the first and second moisture detectors 55 and 56 are naturally arranged below the first and second ball bearings 34 and 35 in the vertical direction in view of the formation position of the through hole 28d. It has become so.

  The first and second moisture detectors 55 and 56 are each formed in a straight line, and are arranged in the worm shaft accommodating portion 30 in a non-contact state in which they are substantially parallel to each other and slightly apart from each other in the radial direction.

  FIG. 7 is a perspective view showing the moisture detection sensor 46, the grommet 49, and the water receiver 57.

  The water receiving portion 57 is formed integrally with the grommet 49, and includes a U-shaped holding portion 57a and a dam portion 57b. The holding portion 57a projects from the end surface of the grommet 49 on the worm shaft housing portion 30 side along the axial direction of the drive shaft 26, and opens upward in the vertical direction. The dam portion 57b is provided on the tip side (the side opposite to the grommet 49 side) of the holding portion 57a and dams the water that has dropped onto the holding portion 57a.

  The holding portion 57a is provided at a position slightly above the inner peripheral surface of the wall recess 28a of the one side wall 28 in the vertical direction. Further, at least a part of each of the first and second moisture detectors 55 and 56 is housed inside the holder 57a, and when the amount of moisture dropped into the holder 57a exceeds a predetermined amount, the moisture is removed. The first and second moisture detectors 55 and 56 are electrically connected via the above.

  The dam portion 57b has arcuate groove-shaped first and second water receiving portion side engaging portions 57c and 57d that engage with the tip portions 55a and 56a of the first and second moisture detecting portions 55 and 56, respectively, on the upper side thereof. Are formed. These first and second water receiving portion side engaging portions 57c and 57d are provided so as to be separated from each other in the radial direction, and when the first and second water detecting portions 55 and 56 are engaged, The first and second moisture detectors 55 and 56 are held in a separated state.

  That is, in the present embodiment, the meat portion between the first water receiving portion side engaging portion 57c and the second water receiving portion side engaging portion 57d of the dam portion 57b is the first and second moisture detecting portion 55. , 56, and is configured as a spacer portion 57e that functions as a spacer member that separates the first moisture detector 55 and the second moisture detector 56 by a predetermined distance.

  FIG. 8 is a block diagram showing an outline of the moisture detection process and the abnormality determination process by the control circuit 36.

  The control circuit 36 has an abnormality handling unit 66 that performs various abnormality handling processes assuming that an abnormality has occurred in the electric power steering device 1 when the moisture detection sensor 46 detects moisture in the housing member 4. ing.

The abnormality handling unit 66 is provided in the control circuit 36 as software in the microcomputer 54. As shown in FIG. 8, the abnormality handling unit 66 includes a storage unit 67 that stores information on moisture detection by the moisture detection sensor 46, a first abnormality determination unit 69 that determines the presence or absence of moisture in the housing member 4, and a later-described abnormality determination unit 69. And a second abnormality determination unit 70 that determines whether or not there is an abnormality in the moisture detection circuits 68A to 68D. The first abnormality determination unit 69 determines the presence or absence of water based on the change in the voltage V _OUT which is the output signal of the water detection circuits 68A to 68D described later.
In addition, the abnormality response unit 66 outputs a warning signal to the speaker 71 mounted on the vehicle or a warning lamp 72 provided on an instrument panel (not shown) when the moisture detection sensor 46 detects moisture, and outputs a warning signal. And are equipped with. The speaker 71 emits a warning sound when a warning signal is input from the warning signal output unit 73, while the warning lamp 72 lights up when a warning signal is input from the warning signal output unit 73, and both are cautioned to the driver. Evoke.
(Structure of moisture detection circuit)
FIG. 9 is a schematic electric circuit diagram showing a moisture detection circuit 68A in a normal state for explaining the basic logic of moisture detection.

  The moisture detection circuit 68A is provided between the first and second moisture detection units 55 and 56 (see FIG. 8) and the A/D converter, more specifically, in the first and second electrodes 47 and 48 and the control device 14. It is provided between the A/D converter and the A/D converter. The moisture detection circuit 68A includes a connection circuit 74 that electrically connects the first and second electrodes 47, 48 and the control device 14. The connection circuit 74 includes a voltage application unit VCC to which a predetermined voltage is applied, a first resistor R1, a second resistor R2, a third resistor R3 for removing noise, and a ground 75. Here, the first and second resistors R1 and R2 are both several tens of kΩ, and the third resistor R3 is several kΩ. In this embodiment, the voltage application unit VCC is, for example, 5V, and the first and second resistors R1 and R2 are both 10 kΩ.

  As shown in FIG. 9, in the connection circuit 74, the positive electrode of the first capacitor C1 is electrically connected to the first electrode 47, one end of the first resistor R1, one end of the second resistor R2, and one end of the third resistor R3. Has been done. The other end of the first resistor R1 is electrically connected to the voltage applying unit VCC. The other end of the third resistor R3 and the positive electrode of the second capacitor C2 are electrically connected to the A/D converter via the common connection point 76.

  Also, as shown in FIG. 9, in the connection circuit 74, the negative electrode of the first capacitor C1 is electrically connected to the second electrode 48 and a common connection point between the second resistor R2 and the ground 75. The other end of the second resistor R2, the negative electrode of the second capacitor C2, and the ground 75 are electrically connected via 77.

In the connection circuit 74 configured as described above, in a normal state, that is, when moisture does not enter the inside of the housing member 4, a current flows as indicated by a solid arrow 78A in FIG. Specifically, in the normal state, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 flows to the A/D converter via the third resistor R3 and the second resistor R2. Through the ground 75. At this time, the voltage V _OUT applied to the A/D converter is 2.5 V according to Ohm's law.

  FIG. 10 is a schematic electric circuit diagram showing a moisture detection circuit 68A at the time of moisture penetration for explaining the basic logic of moisture detection.

In the moisture detection circuit 68A of FIG. 10, the moisture invades the interior of the housing member 4 to cause a short circuit between the first and second electrodes 47 and 48, which causes a resistance R _W. In this embodiment, the resistance R _W is, for example, 10Ω.

In the connection circuit 74 of the water content detection circuit 68A, when water enters the housing member 4, a current flows as indicated by a dashed arrow 80A in FIG. Specifically, at the time of infiltration of water, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 flows to the A/D converter via the third resistor R3, and then flows to the second resistor R2. Through the common connection point 79 to the common connection point 77 via the resistor R _W. At this time, the voltage V _OUT becomes 0.0049V.

FIG. 11 is a diagram showing changes in the voltage V _OUT applied to the A/D converter before and after the infiltration of water into the housing member 4.

In FIG. 11, the current flows along the solid arrow 78A until time t1 when the water has entered the housing member 4 (see FIG. 9), and the voltage V _OUT is higher than the predetermined threshold value A 2. It is set to 0.5V. On the other hand, at the time t1, when water enters, current flows along the broken line arrow 80A (see FIG. 10), and the voltage V _OUT drops to 0.0049 V which is lower than the threshold A.

As described above, in the first embodiment, the first abnormality determination unit 69 determines that the voltage V _OUT, which was higher than the threshold A before the infiltration of water, normally drops to a value lower than the threshold A after the infiltration of water. Therefore, it can be determined that there is water in the housing member 4.

  FIG. 12 is a schematic electric circuit diagram of the moisture detection circuit 68B of the first embodiment.

  The connection circuit 74 of the water content detection circuit 68B includes a voltage application unit VCC, first to third resistors R1 to R3, first and second capacitors C1 and C2, and a ground 75 of the water content detection circuit 68A, and a first noise removal circuit. It includes 4,5 resistors R4 and R5 and a first switching circuit 81. Here, the voltage application unit VCC, the first resistance R1 and the second resistance R2 are 5V, 10 kΩ, and 10 kΩ, respectively, as in the moisture detection circuit 68A. The first switching circuit 81 is a circuit provided for performing an initial diagnosis for determining whether or not there is an abnormality (fault) in the moisture detection circuit 68B. The first switching circuit 81 is a switching element such as a field effect transistor. In this embodiment, the first switching circuit 81 is the FET 1 which is a MOS transistor (MOS-FET).

  The first switching circuit 81 corresponds to the "switching circuit" described in the claims.

  As shown in FIG. 12, in the connection circuit 74, the positive electrode of the first capacitor C1 is connected to the first electrode 47, the drain of the FET1, one end of the first resistor R1, one end of the second resistor R2, and one end of the third resistor R3. It is electrically connected. The other end of the first resistor R1 is electrically connected to the voltage applying unit VCC. The other end of the third resistor R3 and the positive electrode of the second capacitor C2 are electrically connected to the A/D converter via the common connection point 76. The gate of the FET1 is electrically connected to one end of the fourth resistor R4 and one end of the fifth resistor R5 via the common connection point 82. The other end of the fourth resistor R4 is electrically connected to the CPU port.

  Also, as shown in FIG. 12, in the connection circuit 74, the negative electrode of the first capacitor C1 is electrically connected to the second electrode 48 and the source of the FET1, and the second resistor is connected via the common connection point 77. The other end of R2, the other end of the fifth resistor R5, the negative electrode of the second capacitor C2, and the ground 75 are electrically connected. The source of the FET1 is electrically connected to the common connection point 77.

  In FIG. 12, when the FET1 is off, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 passes through the third resistor R3 as shown by a solid arrow 78B in FIG. Flow to the A/D converter and also to the ground 75 via the second resistor R2. Further, when the FET1 is turned on, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 and the common resistor A3 via the third resistor R3 as shown by a broken line arrow 80B in FIG. The current flows to the /D converter, flows to the ground 75 via the second resistor R2, and further flows to the common connection point 77 via the FET1. The FET1 is switched on and off when the ignition is on.

  The connection circuit 74 constitutes a voltage dividing circuit 90 that switches the FET 1 from OFF to ON and divides a predetermined voltage applied to the voltage application unit VCC to the common connection point 77 via the FET 1. The voltage dividing circuit 90 constitutes a voltage dividing circuit which is substantially the same as the circuit (see FIG. 10) when water enters, by switching the FET 1 from OFF to ON, and simulates the state where water entered. Is causing.

  FIG. 13 is an explanatory diagram of an initial diagnosis regarding an abnormality (fault) of the moisture detection circuit 68B of the first embodiment.

  The initial diagnosis of the moisture detection circuit 68B is performed by switching the FET1 on and off at time t1 when the ignition is on, and the first diagnosis executed when the FET1 is off and when the FET1 is on. The second diagnosis is executed.

In the first diagnosis, the current is flowing along the solid arrow 78B (see FIG. 12), and the voltage V _OUT is 2.5V. Here, the voltage V _OUT of 2.5V is between the threshold value B and the threshold value C lower than the threshold value B. In the present embodiment, for convenience of explanation, the threshold value B is set to 4V, for example.

In the second diagnosis, the current flows along the broken line arrow 80B (see FIG. 12), and the voltage V _OUT is 0 V which is lower than the threshold value D. Here, the threshold value D is set to a value lower than the threshold value C. In this embodiment, the threshold value D is set to, for example, 1V for convenience of explanation.

  Next, with reference to Table 1, an initial diagnosis regarding abnormality (fault) of each component of the moisture detection circuit 68B of the second embodiment will be described.

In Table 1, the values located on the upper side of the first diagnosis and the second diagnosis indicate the voltage V _OUT applied to the A/D converter, and “OK” or “NOK (=NOT OK)” on the lower side is The pass/fail judgment in the first diagnosis and the second diagnosis is shown.

“OK” in the first diagnosis indicates when the voltage V _OUT is between the threshold value B and the threshold value C, and “NOK” indicates when the voltage V _OUT is not between the threshold value B and the threshold value C. Shows. Further, “OK” in the second diagnosis indicates when the voltage V _OUT is lower than the threshold value D, and “NOK” indicates when the voltage V _OUT is higher than the threshold value D.

In the initial diagnosis of the moisture detection circuit 68B, the second abnormality determination unit 70 determines that the voltage V _OUT is between the threshold value B and the threshold value C in the first diagnosis, and the voltage V _OUT is the threshold value D in the second diagnosis. It is determined that the moisture detection circuit 68 is normal when the moisture detection circuit 68 falls to a lower value. As a result, the result of the initial diagnosis is “pass”, and in the electric power steering device 1, the steering assist mechanism 3 assists the steering operation of the driver.

On the other hand, in the initial diagnosis, in the first diagnosis, the voltage V _OUT is out of the range between the threshold B and the threshold C, or in the second diagnosis, the voltage V _OUT is higher than the threshold D. , It is determined that the moisture detection circuit 68B is abnormal. As a result, the result of the initial diagnosis is “fail”, the steering assist mechanism 3 does not assist the steering operation of the driver, and the driver is notified of the abnormality through the speaker 71 and the warning light 72 (see FIG. 8). ).

In the initial diagnosis 1, when the first resistor R1 has a disconnection failure, in the first diagnosis, the voltage V _OUT becomes 0V in a state where the current flows along the solid arrow 78B (see FIG. 12). There is. Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 1 is "fail" because "NOK" is determined in the first diagnosis.

Further, in the initial diagnosis 2, when the second resistor R2 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 5 V with the current flowing along the solid arrow 78B (see FIG. 12). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 2 is "fail" because "NOK" is determined in the first diagnosis.

Further, in the initial diagnosis 3, when the third resistor R3 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 0 V with the current flowing along the solid arrow 78B (see FIG. 12). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 3 is “fail” because “NOK” is determined in the first diagnosis.

Further, in the initial diagnosis 4, when the first capacitor C1 has a short circuit failure, in the first diagnosis, the voltage V _OUT is 0 V with the current flowing along the solid arrow 78B (see FIG. 12). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 4 is “fail” because “NOK” is determined in the first diagnosis.

Furthermore, in the initial diagnosis 5, when the second capacitor C2 has a short-circuit fault, in the first diagnosis, the voltage V _OUT is 0 V with the current flowing along the solid arrow 78B (see FIG. 12). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 5 is “fail” because “NOK” is determined in the first diagnosis.

Further, in the initial diagnosis 6, when the FET 1 has a short circuit failure, in the first diagnosis, the voltage V _OUT is 0 V in a state where the current flows along the solid arrow 78B (see FIG. 12). .. Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 6 is “failed” because “NOK” is determined in the first diagnosis.

Furthermore, in the initial diagnosis 7, when the FET 1 has a disconnection failure, in the first diagnosis, the voltage V _OUT becomes 2.5 V while the current flows along the solid line arrow 78B (see FIG. 12). ing. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is higher than the threshold value D, and "NOK" is determined. Therefore, the diagnosis result of the initial diagnosis 7 is "fail" because "NOK" is determined in the second diagnosis.

Further, in the initial diagnosis 8, when the fourth resistor R4 has a disconnection fault, in the first diagnosis, the voltage V _OUT is 2. with the current flowing along the solid arrow 78B (see FIG. 12). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is higher than the threshold value D, and "NOK" is determined. Therefore, the diagnosis result of the initial diagnosis 8 is “fail” because the judgment of “NOK” is made in the second diagnosis.

Further, in the initial diagnosis 9, when the fifth resistor R5 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 2. with the current flowing along the solid arrow 78B (see FIG. 12). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 9 is “pass” because the judgment of “OK” is made in both the first diagnosis and the second diagnosis.

Further, in the initial diagnosis 10, when the CPU is out of order, the voltage V _OUT becomes 2.5 V in the first diagnosis in the state where the current flows along the solid arrow 78B (see FIG. 12). There is. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is higher than the threshold value D, and "NOK" is determined. Therefore, the diagnosis result of the initial diagnosis 10 is “fail” because the judgment of “NOK” is made in the second diagnosis.

Further, in the initial diagnosis 11, when the water detection state is set, the voltage V _OUT is 0 V in the first diagnosis in the state where the current is flowing along the solid arrow 78B (see FIG. 12 ). Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80B (see FIG. 12). Therefore, in the second diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 11 is “fail” because “NOK” is determined in the first diagnosis.

  Here, the water detection state is a state in which the FET 1 is turned on in the moisture detection circuit 68B of FIG. 12 to cause a situation in which moisture has infiltrated, which is being detected.

In the first embodiment, the abnormality of the moisture detection circuit 68B can be determined by the change in the voltage V _OUT due to the switching of the FET1 from OFF to ON. That is, when the voltage V _OUT changes over the threshold value D with the switching of the FET 1 from OFF to ON, that is, when it drops, the moisture detection circuit 68B is normal, and when this voltage V _OUT does not drop. Indicates that the moisture detection circuit 68B is abnormal.

  By determining the abnormality of the moisture detection circuit 68B in this manner, for example, as shown in Table 1 above, regarding the failure of each component of the moisture detection circuit 68B, the initial diagnosis 1 to 8, 10, 11 "fail" It is possible to judge “pass” of the initial diagnosis 9.

  For example, in the electric power steering device described in Patent Document 1, when the moisture detection sensor provided in the boot fails, moisture enters the housing, causing a short circuit in the ECU and ignition. There is a possibility that it may be caused or the gear may be rusted and fixed.

However, in the first embodiment, by determining the abnormality of the moisture detection circuit 68B based on the change of the voltage V _OUT , the abnormality determination is performed in a relatively short time, and the malfunction of the electric power steering device 1 due to the infiltration of moisture is suppressed. can do. As a result, the reliability of the electric power steering device 1 is improved.
[Second Embodiment]
FIG. 14 is a schematic electric circuit diagram of the moisture detection circuit 68C of the second embodiment.

  The connection circuit 74 of the moisture detection circuit 68C is added to the voltage application unit VCC, the first to fifth resistors R1 to R5, the first and second capacitors C1 and C2, the ground 75 and the first switching circuit 81 of the moisture detection circuit 68B. Thus, the sixth and seventh resistors R6 and R7 for removing noise and the second switching circuit 83 are provided. The second switching circuit 83, like the first switching circuit 81, is a switching element such as a field effect transistor. In this embodiment, the second switching circuit 83 is the FET 2 which is a MOS transistor (MOS-FET).

  In the connection circuit 74, the positive electrode of the first capacitor C1 is electrically connected to the first electrode 47, the drain of the FET1, one end of the first resistor R1, one end of the second resistor R2, and one end of the third resistor R3. .. The other end of the first resistor R1 is electrically connected to the voltage applying unit VCC. The gate of the FET1 is electrically connected to one end of the fourth resistor R4 and one end of the fifth resistor R5 via the common connection point 84. The other end of the fourth resistor R4 is electrically connected to the CPU port. The FET1 is connected in series with the FET2, and the source of the FET1 is electrically connected to the drain of the FET2 via the common connection point 85. The common connection point 85 is electrically connected to the second electrode 48. The gate of the FET 2 is electrically connected to one end of the sixth resistor R6 and one end of the seventh resistor R7 via the common connection point 86. The source of the FET2 is electrically connected to the negative electrode of the first capacitor C1, the negative electrode of the second capacitor C2, the other end of the fifth resistor R5 and the other end of the seventh resistor R7. The other end of the sixth resistor R6 is electrically connected to the CPU port.

  In FIG. 14, when both FET1 and FET2 are off, current flows as indicated by the solid arrow 78C in FIG. Specifically, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 flows to the A/D converter via the third resistor R3 and is grounded via the second resistor R2. Flows to 75.

  Further, when both FET1 and FET2 are turned on, a current flows as shown by a dashed arrow 80C in FIG. Specifically, the current flowing from the voltage applying unit VCC to the common connection point 79 via the first resistor R1 flows to the A/D converter via the third resistor R3, and is grounded via the second resistor R2. To the ground 75 via FET1 and FET2.

  Further, when the FET1 is on and the FET2 is off, the current cannot flow along the broken line arrow 80C because it does not flow through the FET2, but substantially flows along the solid line arrow 78C.

  FIG. 15 is an explanatory diagram of an initial diagnosis regarding an abnormality (fault) of the moisture detection circuit 68C according to the second embodiment.

  The initial diagnosis of the moisture detection circuit 68C is performed by switching the FET1 from off to on at the time t1 when the ignition is on, and switching the FET2 from off to on at the time t2 while keeping the FET1 on. The initial diagnosis includes a first diagnosis executed when the FET1 is off and the FET2 is off, a second diagnosis executed when the FET1 is on and the FET2 is off, and a first diagnosis executed when the FET1 is on and the FET2 is off. And a third diagnosis executed when the power switch is on.

In the first diagnosis, the current is flowing along the solid arrow 78C (see FIG. 14), and the voltage V _OUT is 2.5V. Here, threshold values B and C similar to those of the first diagnosis of the first embodiment are set in the first diagnosis of the second embodiment.

Further, in the second diagnosis, the current substantially flows along the solid arrow 78C (see FIG. 14), and the voltage V _OUT is 2.5V. Here, also in the second diagnosis of the second embodiment, the threshold values B and C similar to those in the first diagnosis of the first embodiment are set.

Further, in the third diagnosis, the current is flowing along the dashed arrow 80C (see FIG. 14), and the voltage V _OUT is 0V. Here, the threshold value D similar to that of the second diagnosis of the first embodiment is set for the third diagnosis of the second embodiment.

  Next, with reference to Table 2, an initial diagnosis regarding abnormality (fault) of each component of the moisture detection circuit 68C of the second embodiment will be described.

In the initial diagnosis of the moisture detection circuit 68C, the second abnormality determination unit 70, in the first diagnosis, while the voltage V _OUT of the threshold B and threshold value C, in the second diagnosis, and the voltage V _OUT threshold B It is between the threshold value C and the voltage V _OUT drops to a value lower than the threshold value D in the third diagnosis, so that the moisture detection circuit 68C is determined to be normal. As a result, the result of the initial diagnosis is “pass”, and in the electric power steering device 1, the steering assist mechanism 3 assists the steering operation of the driver.

On the other hand, in the initial diagnosis, the second abnormality determination unit 70, in the first diagnosis, the voltage V _OUT is out from between the threshold value B and threshold value C, and the second diagnosis voltage V _OUT is the threshold B and threshold If at least one of the fact that the voltage V _OUT is higher than the threshold value D in the third diagnosis is satisfied, the moisture detection circuit 68C is abnormal. To judge. As a result, the result of the initial diagnosis is “fail”, the steering assist mechanism 3 does not assist the steering operation of the driver, and the driver is notified of the abnormality through the speaker 71 and the warning light 72 (see FIG. 8). ).

In the initial diagnosis 1, when the first resistor R1 has a disconnection fault, in the first diagnosis, the voltage V _OUT becomes 0V in a state where the current flows along the solid arrow 78C (see FIG. 14). There is. Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 1 is “fail” because “NOK” is determined in the first diagnosis and the second diagnosis.

Further, in the initial diagnosis 2, when the second resistor R2 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 5 V in a state where the current flows along the solid arrow 78C (see FIG. 14). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 5 V in a state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 2 is “fail” because the judgment of “NOK” is made in the first diagnosis and the second diagnosis.

Furthermore, in the initial diagnosis 3, when the third resistor R3 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 0 V with the current flowing along the solid arrow 78C (see FIG. 14). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 3 is “fail” because “NOK” is determined in the first diagnosis and the second diagnosis.

Further, in the initial diagnosis 4, when the first capacitor C1 has a short-circuit fault, the voltage V _OUT is 0 V in the first diagnosis in the state where the current flows along the solid arrow 78C (see FIG. 14). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 4 is “fail” because “NOK” is determined in the first diagnosis and the second diagnosis.

Further, in the initial diagnosis 5, when the second capacitor C2 has a short circuit failure, in the first diagnosis, the voltage V _OUT is 0 V with the current flowing along the solid arrow 78C (see FIG. 14). Is becoming Therefore, in the first diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 5 is “fail” because “NOK” is determined in the first diagnosis and the second diagnosis.

Further, in the initial diagnosis 6, when the FET 1 has a short circuit failure, the voltage V _OUT becomes 2.5V in the first diagnosis in the state where the current flows along the solid arrow 78C (see FIG. 14). ing. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 6 is “pass” because the judgment of “OK” is made in all of the first to third diagnoses.

Further, in the initial diagnosis 7, when the FET 1 has a disconnection failure, the voltage V _OUT becomes 2.5V in the first diagnosis in the state where the current flows along the solid arrow 78C (see FIG. 14). ing. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is higher than the threshold value D, and “NOK” is determined. Therefore, the diagnosis result of the initial diagnosis 7 is "fail" because "NOK" is determined in the third diagnosis.

Further, in the initial diagnosis 8, when the FET 2 has a short-circuit fault, the voltage V _OUT becomes 2.5 V in the first diagnosis in the state where the current flows along the solid line arrow 78C (see FIG. 14). ing. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 0 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is out of the range between the threshold value B and the threshold value C, and “NOK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 8 is “fail” because the judgment of “NOK” is made in the second diagnosis.

Further, in the initial diagnosis 9, when the FET 2 has a disconnection failure, the voltage V _OUT becomes 2.5 V in the first diagnosis in the state where the current flows along the solid line arrow 78C (see FIG. 14 ). ing. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is higher than the threshold value D, and “NOK” is determined. Therefore, the diagnosis result of the initial diagnosis 9 is "fail" because "NOK" is determined in the third diagnosis.

Further, in the initial diagnosis 10, when the fourth resistor R4 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 2. while the current flows along the solid arrow 78C (see FIG. 14). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is higher than the threshold value D, and “NOK” is determined. Therefore, the diagnosis result of the initial diagnosis 10 is “fail” because the judgment of “NOK” is made in the third diagnosis.

Further, in the initial diagnosis 11, when the fifth resistor R5 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 2. with the current flowing along the solid arrow 78C (see FIG. 14). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 11 is “pass” because the judgment of “OK” is made in all of the first to third diagnoses.

Further, in the initial diagnosis 12, when the sixth resistor R6 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 2. while the current is flowing along the solid arrow 78C (see FIG. 14). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is higher than the threshold value D, and “NOK” is determined. Therefore, the diagnosis result of the initial diagnosis 12 is “fail” because the judgment of “NOK” is made in the third diagnosis.

Further, in the initial diagnosis 13, when the seventh resistor R7 has a disconnection failure, in the first diagnosis, the voltage V _OUT is 2. while the current flows along the solid arrow 78C (see FIG. 14). It is 5V. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 13 is “pass” because the judgment of “OK” is made in all of the first to third diagnoses.

Further, in the initial diagnosis 14, when the CPU is out of order, the voltage V _OUT becomes 2.5 V in the first diagnosis in the state where the current flows along the solid arrow 78C (see FIG. 14). There is. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 2.5 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is higher than the threshold value D, and “NOK” is determined. Therefore, the diagnosis result of the initial diagnosis 14 is "fail" because "NOK" is determined in the third diagnosis.

Further, in the initial diagnosis 15, the voltage V _OUT is 2.5 V in the first diagnosis when the current is flowing along the solid arrow 78C (see FIG. 14) in the water detection state. .. Therefore, in the first diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Further, in the second diagnosis, the voltage V _OUT is 2.5 V in the state where the current substantially flows along the solid arrow 78C (see FIG. 14). Therefore, in the second diagnosis, the voltage V _OUT is between the threshold value B and the threshold value C, and “OK” is determined. Furthermore, in the third diagnosis, the voltage V _OUT is 0 V in the state where the current flows along the broken line arrow 80C (see FIG. 14 ). Therefore, in the third diagnosis, the voltage V _OUT is lower than the threshold value D, and "OK" is determined. Therefore, the diagnosis result of the initial diagnosis 15 is “pass” because the judgment of “OK” is made in all of the first to third diagnoses.

In the second embodiment, compared with the first embodiment, the diagnosis is increased by one stage like the second diagnosis, and then the second abnormality determination unit 70 sets the FET1 and the FET2 to the ON state. Switching control to the off state is performed, and it is determined whether or not the voltage V _OUT changes across the threshold value D, that is, drops. That is, the second abnormality determination unit 70 determines whether or not there is an abnormality in the moisture detection circuit 68C based on the combination of the on/off states of the FET1 and FET2 and the voltage V _OUT output from the moisture detection circuit 68C. .. Therefore, by considering the combination of the ON/OFF switching of FET1 and FET2 and the combination of the voltage V _OUT of the moisture detection circuit 68C at the time of switching in a plurality of patterns, the moisture detection circuit 68C can be compared with the case where the determination is made in one pattern. It is possible to improve the accuracy of the determination regarding the abnormality.

  For example, in the first example, as shown in Table 1, the diagnosis result of the short circuit failure of the FET 1 of the initial diagnosis 6 and the water detection state of the initial diagnosis 11 was “fail”. However, in the second embodiment, as shown in Table 2 above, the diagnosis result of the short circuit failure of the FET 1 of the initial diagnosis 6 and the water detection state of the initial diagnosis 15 is “pass”. Therefore, by using the moisture detection circuit 68C, the result of the initial diagnosis can be further narrowed down, and the accuracy of abnormality determination is further improved.

[Third Embodiment]
FIG. 4 is a schematic electric circuit diagram of the moisture detection circuit 68D of the third embodiment.

  In the third embodiment, as shown in FIG. 16, the first electrode 47 is electrically connected to the third electrode 91, while the second electrode 48 is electrically connected to the fourth electrode 92. There is. Then, the first and second electrodes 47, 48 are electrically connected to the A/D converter via the moisture detection circuit 68D.

  The connection circuit 74 of the moisture detection circuit 68D includes a voltage application unit VCC, eighth to twelfth resistors R8 to 12, a third capacitor C3, and grounds 94 to 96.

  In the connection circuit 74, the voltage application unit VCC is electrically connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is electrically connected to the first electrode, one end of the ninth resistor R9, and one end of the tenth resistor R10. The other end of the ninth resistor R9 is electrically connected to one end of the eleventh resistor R11 and the positive electrode of the third capacitor C3. The other end of the eleventh resistor R11 is electrically connected to the A/D converter. The negative electrode of the third capacitor C3 is electrically connected to the ground 94. The other end of the tenth resistor R10 is electrically connected to the ground 95. One end of the twelfth resistor R12 is electrically connected to the second electrode 48, while the other end of the twelfth resistor R12 is electrically connected to the ground 96.

  Furthermore, the moisture detection circuit 68D includes a second connection circuit (diagnosis circuit) 93 that electrically connects the third and fourth electrodes 91 and 92 and the control device 14, and the third and fourth electrodes 91 and 92 are , And is electrically connected to the microcomputer port via the second connection circuit 93.

  The second connection circuit 93 includes a third switching circuit 97, thirteenth to fifteenth resistors R13 to 15, a level shifter 98, and a ground 99. The third switching circuit 97 is a switching element such as a field effect transistor. In this embodiment, the third switching circuit 97 is the FET 3 which is a MOS transistor (MOS-FET).

  In the second connection circuit 93, one end of the thirteenth resistor R13 is electrically connected to the third electrode 91, while the other end of the thirteenth resistor R13 is electrically connected to the drain of the FET3. The gate of the FET 3 is electrically connected to one end of the fourteenth resistor R14 and one end of the fifteenth resistor R15. The other end of the fourteenth resistor R14 is electrically connected to one end of the level shifter 98. The other end of the level shifter 98 is electrically connected to the microcomputer port. The other end of the fifteenth resistor R15 is connected to the ground 99.

  When the FET3 is off, the current flowing from the voltage applying section VCC to the common connection point 100 via the eighth resistor R8 is A/D via the ninth and eleventh resistors R9 and R11 as shown by a solid arrow 78D. The current flows to the converter and also to the ground 95 via the tenth resistor R10.

  When the FET 3 is on, the current that has flowed from the voltage application unit VCC to the common connection point 100 via the eighth resistor R8 flows as indicated by the dashed arrow 80D. Specifically, this current flows to the A/D converter via the ninth and eleventh resistors R9 and R11, to the ground 95 via the tenth resistor R10, and further to the first electrode 47 and the third electrode 91. , The thirteenth resistor R13, the FET3, the fourth electrode 92, the second electrode 48, and the twelfth resistor R12 to the ground 96.

In the third embodiment, it is possible to determine the abnormality of the moisture detection circuit 68D based on the change in the voltage V _OUT due to the switching of the FET 3 from OFF to ON.
In addition, in the third embodiment, a third electrode 91 electrically connected to the first electrode 47 and a fourth electrode 92 electrically connected to the second electrode 48 are provided outside the moisture detection circuit 68D. Therefore, when the FET 3 is turned on, a current flows through the first and second electrodes 47 and 48. Therefore, for example, disconnection of the first and second electrodes 47, 48 and disconnection in the moisture detection sensor 46 can be determined based on the change in the voltage V _OUT accompanying the switching of the FET 3 from OFF to ON.
Further, by providing the second connection circuit 93, it is possible to accurately determine the abnormality of the moisture detection circuit 68D even when the moisture detection units 55 and 56 are detecting moisture.

  In each of the above-described embodiments, the example in which the field effect transistors FET1 and FET2 are used as the switching element is disclosed, but the present invention can be applied to the configuration using the relay as the switching element.

(Effects of the first to third embodiments)
The effects obtained by the power steering device 1 according to the first to third embodiments will be listed below.

(1) The power steering device includes a steering mechanism 2 that transmits the rotation of the steering wheel to the steered wheels, an electric motor 13 that applies a steering force to the steering mechanism 2, and an electric motor that is provided between the steering mechanism 2 and the electric motor 13. A worm gear 15 that transmits the rotational force of the motor 13 to the steering mechanism 2, a housing member 4 that houses at least a part of the steering mechanism 2, the worm gear 15, and the electric motor 13 are provided in the housing member 4, and are separated from each other. Of the moisture detectors 55 and 56 for detecting moisture, the controller 14 having the microcomputer 54, the moisture detectors 55 and 56, and the controller 14. A connection circuit 74 that is provided between the first electrode 47 and the second electrode 48 and electrically connects the control device 14 to each other, and a voltage application unit VCC that is provided in the connection circuit 74 and to which a predetermined voltage is applied. A first abnormality determination for determining the presence/absence of moisture in the housing member 4 based on the change in the voltage V _OUT which is the output signal of the moisture detection circuits 68A to 68D, which is provided in the moisture detection circuits 68A to 68D provided and the control device 14. The controller 69 includes a unit 69 and a second abnormality determination unit 70 that is provided in the control device 14 and determines whether or not there is an abnormality in the moisture detection circuits 68B to 68D.

  Therefore, the reliability of the device can be improved by making an abnormality determination of the moisture detection circuits 68B to 68D.

(2) The water content detection circuit 68B includes the FET 1, and the second abnormality determination unit 70 determines whether the water content detection circuit 68B has an abnormality based on the change in the voltage V _OUT of the water content detection circuit 68B associated with the switching on and off of the FET 1. Determine the presence or absence.

  Therefore, the presence/absence of an abnormality is determined by the change in the voltage associated with the on/off operation of the FET 1, so that the presence/absence of abnormality can be determined in a short time.

  (3) FET1 is a switching element.

  Therefore, it is possible to configure the circuit 68B that detects an abnormality in the electronic circuit.

  (4) The moisture detection circuit 68B has a voltage dividing circuit 90 that divides the predetermined voltage applied to the voltage applying unit VCC when the FET1 is in the ON state.

  Therefore, when the voltage drops normally due to the partial pressure, it is possible to determine that the moisture detection circuit 68B is normal.

(5) The moisture detection circuit 68C includes the FET2, and the second abnormality determination unit 70 controls the switching of each of the FET1 and FET2 to the ON state and the OFF state so that the FET1 and the FET2 are turned on and off. Whether or not there is an abnormality in the moisture detection circuit 68 is determined based on the combination of the voltage V _OUT of the moisture detection circuit 68C.

Therefore, the FET 1 and FET 2 are switched on and off, respectively, and the combination and the combination of the voltage V _OUT of the moisture detection circuit 68C at that time are taken into consideration in a plurality of patterns, so that an abnormality judgment is made as compared with the case of making a judgment in one pattern The accuracy can be improved.

(6) The moisture detectors 55 and 56 each include the third electrode 91 electrically connected to the first electrode 47 and the fourth electrode 92 electrically connected to the second electrode 48, and the moisture detector circuit 68D. Includes a second connection circuit 93 that electrically connects the third electrode 91 and the fourth electrode 92 to the control device 14, and the second abnormality determination unit 70 is based on the change in the voltage V _OUT of the second connection circuit 74. The presence or absence of water in the housing member 4 is determined.

  Therefore, by providing the second connection circuit 93, it is possible to accurately determine the abnormality of the moisture detection circuit 68D even when the moisture detection units 55 and 56 are detecting moisture.

  As a power steering device based on the above-described embodiment, for example, the following modes are conceivable.

In one aspect thereof, the power steering device includes a steering mechanism that transmits the rotation of the steering wheel to the steered wheels, and an electric motor that applies a steering force to the steering mechanism.
A transmission mechanism (reducer) provided between the steering mechanism and the electric motor for transmitting the rotational force of the electric motor to the steering mechanism; and at least a part of the steering mechanism, the transmission mechanism, and the electric motor. A housing for accommodating, a first terminal portion and a second terminal portion provided in the housing and spaced apart from each other, a moisture detector for detecting moisture, a controller having a microcomputer, and A connection circuit provided between the moisture detector and the control device to electrically connect the first terminal part and the second terminal part to the control device, and a predetermined voltage applied to the connection circuit. A first abnormality determination which is provided in the controller and which determines the presence or absence of moisture in the housing based on a change in voltage which is an output signal of the moisture detection circuit. And a second abnormality determination unit that is provided in the control device and determines whether or not there is an abnormality in the moisture detection circuit.

  In a preferred aspect of the power steering device, the moisture detection circuit includes a switching circuit, and the second abnormality determination unit is configured to change the voltage of the moisture detection circuit based on a change in ON/OFF of the switching circuit. Determine whether there is an abnormality in the moisture detection circuit.

  In another preferred aspect, in any one of the aspects of the power steering device, the switching circuit is a switching element.

  In another preferred aspect, in any one of the aspects of the power steering device, the moisture detection circuit divides the predetermined voltage applied to the voltage application unit when the switching circuit is in an ON state. have.

  In another preferred aspect, in any one of the aspects of the power steering device, the moisture detection circuit includes a second switching circuit, and the second abnormality determination unit includes a switching circuit and a second switching circuit. Each of them is controlled to be switched between an on state and an off state, and an abnormality of the moisture detection circuit is detected based on a combination of the on/off states of the switching circuit and the second switching circuit and the voltage of the moisture detection circuit. Determine the presence or absence.

  In another preferred aspect, in any one of the aspects of the power steering device, the moisture detection unit is electrically connected to the third terminal unit electrically connected to the first terminal unit, and electrically connected to the second terminal unit. A second connection circuit that electrically connects the third terminal unit and the fourth terminal unit to the control device; and the second abnormality determination unit. Determines the presence/absence of water in the housing based on the change in the voltage of the second connection circuit.

DESCRIPTION OF SYMBOLS 1... Electric power steering device, 2... Steering mechanism, 3... Steering assist mechanism, 4... Housing member, 11... Boots, 13... Electric motor, 14... Control device (ECU), 15... Worm gear, 47... First electrode, 48... Second electrode, 55... First moisture detector, 56... Second moisture detector, 68A to 68D. ..Moisture detection circuit, 69... First abnormality determination section, 70... Second abnormality determination section, VCC... Voltage application section, R1... First resistance, R2... Second resistance, 74... Connection circuit, 81... First switching circuit (FET1), 83... Second switching circuit (FET2), 91... Third electrode, 92... Fourth electrode, 93 ...Second connection circuit, 97...Third switching circuit (FET3)

Claims (6)

A steering mechanism that transmits the rotation of the steering wheel to the steered wheels,
An electric motor for applying a steering force to the steering mechanism,
A transmission mechanism that is provided between the steering mechanism and the electric motor and transmits the rotational force of the electric motor to the steering mechanism;
A housing that houses at least a part of the steering mechanism, the transmission mechanism, and the electric motor;
A moisture detector provided in the housing, having a first terminal portion and a second terminal portion provided separately from each other, for detecting moisture;
A control device having a microcomputer;
A connection circuit provided between the moisture detection unit and the control device and electrically connecting the first terminal unit and the second terminal unit to the control device, and a predetermined voltage provided in the connection circuit. A moisture detection circuit including an applied voltage application unit,
A first abnormality determination unit provided in the control device, for determining the presence or absence of water in the housing based on a change in voltage that is an output signal of the water detection circuit;
A second abnormality determination unit provided in the control device, for determining whether or not there is an abnormality in the moisture detection circuit;
A power steering device comprising: The power steering device according to claim 1, wherein the moisture detection circuit includes a switching circuit,
The power steering apparatus, wherein the second abnormality determination unit determines whether or not there is an abnormality in the water content detection circuit based on a change in voltage of the water content detection circuit caused by switching on/off of the switching circuit.   The power steering device according to claim 2, wherein the switching circuit is a switching element.   The power steering device according to claim 2, wherein the moisture detection circuit includes a voltage dividing circuit that divides the predetermined voltage applied to the voltage applying unit when the switching circuit is in an ON state. Power steering device The power steering device according to claim 2, wherein the moisture detection circuit includes a second switching circuit,
The second abnormality determination unit controls switching of the switching circuit and the second switching circuit to an ON state and an OFF state, respectively, and an ON state and an OFF state of the switching circuit and the second switching circuit, respectively. A power steering apparatus, which determines whether or not there is an abnormality in the moisture detection circuit based on a combination of the voltage of the moisture detection circuit and the voltage of the moisture detection circuit. The power steering device according to claim 1, wherein the moisture detector is a third terminal electrically connected to the first terminal and a fourth terminal electrically connected to the second terminal. Section,
The moisture detection circuit includes a second connection circuit that electrically connects the third terminal portion and the fourth terminal portion to the control device ,
The power steering device, wherein the second abnormality determination unit determines the presence or absence of water in the housing based on a change in the voltage of the second connection circuit.