JP6651435B2 - Control device for vehicle equipment - Google Patents

Description

  The present invention relates to a control device that controls a driving unit of a vehicle-mounted device.

  2. Description of the Related Art As a conventional control device for a vehicle-mounted device, for example, a control device described in Patent Literature 1 below is known.

  The control device controls an electric motor which is a driving unit of an electric power steering device. The CPU performs various calculations, and a state amount detection device detects a current value flowing through the electric motor as a current value signal which is an analog signal. And a current detecting resistor as a unit. Then, when the current value signal is input to the CPU, the control device performs feedback control of the electric motor by the CPU such that the current value matches a target current value calculated by calculation.

Japanese Patent No. 4089435

  By the way, in recent years, from the viewpoint of safety, it is demanded to make each component of the control device redundant. Even in the configuration of the conventional control device, a current value signal detected via a current detecting resistor is required. Is considered to be a double system. In such a case, when an abnormality occurs in a circuit for transmitting one current value signal (first signal) to the CPU, the one current value signal is compared with the other current value signal (second signal). By doing so, the abnormality can be detected.

  However, in the above-described configuration, when an abnormality due to a short circuit occurs between the first signal circuit and the second signal circuit, the short circuit causes the first and second signals to be substantially the same. Since the value indicates a value, the abnormality cannot be detected.

  The present invention has been devised in view of the conventional circumstances, and has a control device for a vehicle-mounted device capable of detecting an abnormality due to a short circuit between a circuit for detecting a first signal and a circuit for detecting a second signal. It is intended to provide.

  According to the present invention, in one aspect, in particular, provided between a CPU that calculates a command signal for controlling a drive unit of a vehicle-mounted device and a state amount detection unit that detects a state amount of the vehicle-mounted device, An amplitude changing section for changing the amplitude of the first signal detected by the state quantity detecting section; a first signal provided in the CPU and passing through the amplitude changing section; and a second signal detected by the state quantity detecting section. And an abnormality judging unit for judging the presence or absence of an abnormality in the device by comparing the signal with a signal.

  ADVANTAGE OF THE INVENTION According to this invention, the abnormality by the short circuit between the circuit which detects a 1st signal, and the circuit which detects a 2nd signal can be detected.

1 is a schematic diagram of a power steering device to which a control device according to the present invention is applied. It is a longitudinal section of the same power steering device. FIG. 2 is a system configuration diagram of a control device and an electric system including a motor and a sensor. FIG. 3 is a control block diagram illustrating an arithmetic circuit configuration of a CPU. FIG. 3 is a diagram illustrating details of an inverter circuit and a current detection circuit. 7A and 7B are diagrams illustrating a short-circuit diagnosis between the first signal circuit and the second signal circuit by the abnormality determination unit, wherein FIG. 9A illustrates a normal state and FIG. 9B illustrates a short-circuit state. 9A and 9B are diagrams illustrating a diagnosis of a short circuit between the first signal circuit and the second signal circuit by the abnormality determination unit according to the second embodiment of the present invention, wherein FIG. Is represented. It is a flowchart which shows the short circuit detection process between the circuits which detect the 1st, 2nd signal by the control apparatus which concerns on 2nd Embodiment.

  Hereinafter, an embodiment of a control device for a vehicle-mounted device according to the present invention will be described with reference to the drawings. In the following, an example in which the control device is applied to a power steering device as a vehicle-mounted device is shown.

[First Embodiment]
FIG. 1 is a perspective view of a power steering device according to a first embodiment of the present invention.

  As illustrated, the power steering device includes a steering mechanism 1 that steers a pair of steered wheels (not shown) based on a steering operation performed by a driver, and a steering assist mechanism 2 that assists the steering operation of the driver. . At least a part of each of the steering mechanism 1 and the steering assist mechanism 2 is housed in a housing 3 made of a metal material such as an aluminum alloy.

  FIG. 2 is a longitudinal sectional view of the power steering device.

  The steering mechanism 1 includes a steering shaft 4 connected to a steering wheel (not shown) arranged in the driver's cab of the vehicle, a rack bar 5 as a steering shaft linked to the steered wheels, a steering shaft 4 and a rack bar. And a conversion mechanism 6 for linking the control mechanism 5 with the conversion mechanism 5. The conversion mechanism 6 is a so-called rack composed of pinion teeth (not shown) formed on the outer periphery of the steering shaft 4 (output shaft 8 described later) and rack teeth (not shown) formed on the outer periphery of the rack bar 5. -It is a pinion mechanism.

  The steering shaft 4 has one end in the axial direction connected to the steering wheel so as to rotate integrally with the steering wheel, and one end in the axial direction is connected to the other end in the axial direction of the input shaft 7 via a torsion bar (not shown). An output shaft 8.

  The rack bar 5 has both ends in the axial direction linked to the pair of steered wheels via tie rods 9, 9 and a pair of knuckle arms, respectively. Thus, when the rack bar 5 moves in the axial direction, the knuckle arms are pulled through the tie rods 9 to change the directions of the pair of steered wheels.

  The rack bar 5 is accommodated in a rack bar accommodating portion 11 of a substantially cylindrical rack housing 10 constituting a part of the housing 3 so as to be movable in the axial direction with both axial ends exposed to the outside. ing. The rack housing 10 is formed by casting into two parts in the axial direction. The first housing 12 accommodates one end of the rack bar 5 in the axial direction, and the first housing 12 accommodates the other end of the rack bar 5 in the axial direction. The two housings 13 are fastened with a plurality of bolts (not shown). The rack bar housing 11 includes a first rack bar housing 14 that passes through the inside of the first housing 12 in the axial direction, and a second rack bar housing 15 that passes through the inside of the second housing 13 in the axial direction. , Is constituted.

  Boots 16, 16 formed in a bellows shape are attached to both ends in the axial direction of the rack housing 10 so as to straddle the tie rods 9, 9. These boots 16, 16 are formed of an elastic material such as a synthetic rubber material so as to secure a predetermined flexibility, so that water, dust and the like enter the inside of the housing 3.

  The steering assist mechanism 2 includes an electric motor 17 that is a driving unit that generates a steering assist force, a transmission mechanism 18 that transmits the driving force of the electric motor 17 to the rack bar 5, and various types that detect various state quantities of the power steering device. It includes a sensor and a control device 19 that drives and controls the electric motor 17 based on signals output from the various sensors.

  Among the various sensors, a steering angle sensor 20 that detects a steering angle, which is a rotation amount from a neutral position of the steering wheel, and a torque sensor 21 that detects a steering torque input to the steering shaft 4 are both a steering shaft 4. Is housed in a sensor housing 22 which is a part of the housing 3 formed so as to surround the outer periphery of the sensor housing 22.

  The steering angle sensor 20 is attached to the outer periphery of the input shaft 7 of the steering shaft 4, and detects the steering angle based on the rotation angle of the input shaft 7. The steering angle sensor 20 has main and sub steering angle detection units 20a and 20b, each of which detects the steering angle (see FIG. 3).

  The torque sensor 21 is provided so as to straddle between the input shaft 7 and the output shaft 8, and detects the steering torque based on a displacement amount of a relative rotation between the input shaft 7 and the output shaft 8. The torque sensor 21 has main and sub torque detectors 21a and 21b, each of which detects a steering torque (see FIG. 3).

  The steering angle sensor 20 and the torque sensor 21 are electrically connected to the control device 19 via a harness (not shown) provided along the outer periphery of the rack housing 10.

  The electric motor 17 is a so-called three-phase AC motor driven based on three-phase AC power, and includes a motor housing 23 forming a part of the housing 3 and a motor element provided in the motor housing 23. ing.

  The motor housing 23 has a cylindrical tubular portion 23a that houses the motor element therein, and first and second end wall portions 23b and 23c that close openings of the tubular portion 23a, respectively. I have.

  The motor element includes a cylindrical stator 26 fixed to the inner peripheral surface of the cylindrical portion 23a by shrink fitting or the like, and a cylindrical rotor disposed on the inner peripheral side of the stator 26 via a predetermined radial gap. 27, and a motor shaft 28 fixed to the inner peripheral side of the rotor 27 so as to be integrally rotatable and outputting the rotation of the rotor 27.

  The stator 26 is configured by winding U-phase, V-phase, and W-phase coils 26u, 26v, 26w (see FIG. 5) around a stator core (not shown) formed by laminating a plurality of thin plates. In the present embodiment, the coils 26u, 26v, 26w are connected by a so-called Y connection (star connection), but they may be connected by a delta connection.

  The motor shaft 28 has both ends 28a, 28b exposed from the motor housing 23 through through holes formed in the first and second end walls 23b, 23c, respectively. Among these, the one end 28a on the opposite side to the control device 19 faces a transmission mechanism housing 31 described later that houses the transmission mechanism 18. On the other hand, the other end 28b faces a control device housing portion 43 for housing the control device 19, which will be described later.

  The motor shaft 28 includes a first ball bearing 29 provided between the outer peripheral surface on the one end 28a side and the inner peripheral surface of the through hole of the first end wall 23b, and an outer peripheral surface on the other end 28b side. It is rotatably supported by a second ball bearing 30 provided between the second end wall portion 23c and the inner peripheral surface of the through hole.

  The transmission mechanism 18 is housed in a transmission mechanism housing portion 31 of the housing 3, and includes an input pulley 32 and an output pulley 33, a belt 34 wound between the pulleys 32 and 33, and an output pulley. A ball screw mechanism 35 for converting the rotation of the rack bar 5 into the axial movement of the rack bar 5 while reducing the rotation thereof.

  The transmission mechanism housing part 31 includes a first transmission mechanism housing part 36 provided at an end of the first rack bar housing part 14 on the second housing 13 side in an enlarged shape, and a first rack bar housing part 15 of the first rack bar housing part 14. It is formed by joining a second transmission mechanism accommodating portion 37 provided in an end portion on the side of the housing 12 to have an enlarged diameter.

  The input-side pulley 32 is formed in a cylindrical shape having a relatively small diameter with respect to the output-side pulley 33, and is press-fitted and fixed to one end 28a of the motor shaft 28 of the electric motor 17 through a through-hole formed in the inner peripheral side. Have been.

  The output side pulley 33 is arranged on the outer peripheral side of the rack bar 5 and is linked to the rack bar 5 via a ball screw mechanism 35. More specifically, the output pulley 33 has a cylindrical shape with a relatively large diameter and a bottom with respect to the input pulley 32, is fixed to an outer periphery of a nut 38 of the ball screw mechanism 35, and rotates together with the nut 38. It has become.

  The belt 34 is an endless V-belt in which glass fiber, steel wire, or the like is embedded as a core material, and rotates the input pulley 32 and the output pulley 33 synchronously to rotate the input pulley 32. The force is transmitted to the output pulley 33.

  The ball screw mechanism 35 has a cylindrical nut 38 disposed on the outer peripheral side of the rack bar 5, a ball circulation groove 39 formed between the nut 38 and the rack bar 5, and rolls into the ball circulation groove 39. A plurality of balls 40 are provided so as to be able to be provided, and a circulation mechanism (not shown) for circulating each ball 40 from one end of the ball circulation groove 39 to the other end.

  The nut 38 is rotatably supported via a ball bearing 41 housed in the first transmission mechanism housing part 36. The ball bearing 41 is provided between the inner race part 41a formed integrally with the nut 38, the outer race part 41b fixed to the inner peripheral surface of the first transmission mechanism housing part 36, and the inner race part 41a and the outer race part 41b. And a plurality of balls 41c accommodated so as to be rollable. In the present embodiment, the inner race 41a is formed integrally with the nut 38. However, the inner race 41a and the nut 38 may be formed separately.

  The ball circulation groove 39 includes a shaft-side ball screw groove 39a provided on the outer peripheral side of the rack bar 5 and having a spiral groove shape, and a nut side provided with a spiral groove shape provided on the inner peripheral side of the nut 38. And a ball screw groove 39b.

  The control device 19 includes a control housing 42 that forms a part of the housing 3, and a control board 44 housed in a control device housing 43 of the control housing 42.

  The control housing 42 has a cylindrical body 45 whose one end on the electric motor 17 side covers the outer periphery of the motor housing 23, and a cover 46 for closing an opening on the other end side of the body 45.

  The control board 44 has a conductor pattern (not shown) formed on both front and back surfaces of a board made of a non-conductive resin material typified by a glass epoxy resin, and a large number of electronic components are mounted on the conductor pattern. It consists of.

  Although not shown in FIG. 2, a motor rotation angle sensor, which is one of the various sensors and detects the motor rotation angle of the rotor 27 of the electric motor 17, is provided on the control board 44. 47 (see FIG. 3) is provided.

  The motor rotation angle sensor 47 detects the rotation angle of the motor shaft 28 (rotor 27) based on a change in a magnetic field generated by a magnet (not shown) attached to the other end 28b of the motor shaft 28. The motor rotation angle sensor 47 has main and sub motor rotation angle detectors 47a and 47b, each of which detects the rotation angle of the motor shaft 28 (see FIG. 3).

  FIG. 3 is a system configuration diagram of an electric system including the control device 19, the electric motor 17, and various sensors.

  As shown in the figure, the control board 44 of the control device 19 includes a power supply circuit 51 serving as a power supply on the control board 44, a CPU 52 for performing various arithmetic processing, and a pulse width modulation signal (PWM signal) from the CPU 52. A pre-driver 53, which is an integrated circuit to be inputted, and an inverter circuit 54 driven by the pre-driver 53 are provided.

  When power VB is supplied from the battery Batt with the ON operation of the ignition switch IGN-SW of the vehicle, the power supply circuit 51 appropriately reduces the power VB while reducing the CPU 52, the sensors 20, 21, 47, and the pre-driver 53. To supply.

  The CPU 52 receives a vehicle speed signal Vs detected by a vehicle speed sensor or the like installed on a differential gear (not shown) via a CAN communication circuit 55.

  The CPU 52 is electrically connected to the main and sub steering angle detection units 20a and 20b of the steering angle sensor 20, and the main and sub steering angle signals θs (Main) and θs from the detection units 20a and 20b, respectively. (Sub) is input.

  Similarly, the CPU 52 is also electrically connected to the main and sub torque detectors 21a and 21b of the torque sensor 21, and the main and sub torque signals Tr (Main) and Tr (Main) are output from the detectors 21a and 21b, respectively. Sub) is input.

  Further, the CPU 52 is also electrically connected to main and sub motor rotation angle detection units 47a and 47b of the motor rotation angle sensor 47, and from these detection units 47a and 47b, respectively, a main and sub motor rotation angle signal θm ( Main) and θm (Sub) are input.

  When receiving the PWM signal from the pre-driver 53, the inverter circuit 54 converts the power VB from the battery Batt from DC to three-phase AC according to the PWM signal and supplies the power VB to the electric motor 17.

  Further, between the battery Batt and the inverter circuit 54, a fail-safe relay 56 configured to be able to cut off the power VB transmitted from the battery Batt to the inverter circuit 54 is provided.

  The fail-safe relay 56 receives the cutoff signal Sb output from the CPU 52 or the CPU monitoring unit 57 when the CPU 52 determines that continuation of the steering assist is difficult, or when the CPU monitoring unit 57 detects an abnormality of the CPU 52. In this case, the power VB sent from the battery Batt to the inverter circuit 54 is cut off. The CPU monitoring unit 57 determines the state of the CPU 52 by Q & A (Question and Answer). That is, the CPU monitoring unit 57 transmits a predetermined question to the CPU 52, and determines that the CPU 52 is abnormal when the answer to the question is incorrect.

  Further, between the inverter circuit 54 and the ground GRD, there is provided a current sensor 58 which is a state quantity detecting unit for detecting a motor current value Im flowing to the electric motor 17 which is one of the state quantities. .

  The current sensor 58 is a so-called shunt resistor, and detects a motor current value Im based on a potential difference between both ends of the shunt resistor.

  The motor current value Im detected by the current sensor 58 is converted to analog main and sub current value signals Imm and Ims via a current detection circuit 59 provided between the CPU 52 and the current sensor 58. It is redundant. These redundant current value signals Imm and Ims are amplified in amplitude based on the amplification commands AmpM and AmpS output from the CPU 52, input to the CPU 52, and then subjected to the control processing of the CPU 52. It has become.

  Specifically, after the main current value signal Imm is input to the CPU 52 in a state where it is basically amplified to the same magnification (substantially not amplified), it is subjected to feedback control of the electric motor 17. You.

  On the other hand, the amplitude of the sub current value signal Ims is appropriately amplified by the CPU 52. When the signal is amplified, the motor overcurrent detection process and the short-circuit diagnosis process between the first and second current detection circuits 78 and 79 to be described later through which the main and sub current value signals Imm and Ims flow. Provided. On the other hand, when the amplitude is input to the CPU 52 without being amplified, the signal is subjected to a redundancy monitoring process by comparison with the main current value signal Imm.

  Note that, of these main and sub current value signals Imm and Ims, the main current value signal Imm corresponds to the second signal of the present invention, and the sub current value signal Ims corresponds to the first signal of the present invention.

  FIG. 4 is a control block diagram showing the arithmetic circuit configuration of the CPU 52.

  As shown in the figure, the CPU 52 includes a command signal calculation unit 61 that calculates a command signal Io for controlling the electric motor 17, and a motor control unit that drives and controls the electric motor 17 via a pre-driver 53 and the like based on the command signal Io. 62.

  Further, the CPU 52 includes a fail-safe determining unit 63 that determines whether the steering assist mechanism 2 requires a fail-safe, and a fail-safe determining unit that performs various fail-safe processes based on the determination result of the fail-safe determining unit 63. And a processing unit 64.

  The command signal calculator 61 calculates a basic signal Ib from the vehicle speed signal Vs and the main torque signal Tr (Main) based on an assist Map 65 prepared in advance. At the same time, the command signal calculation unit 61 generates a correction signal Ic for improving the returnability of the steering wheel to the neutral position by the steering assist control unit 66 based on the main steering angle signal θs (Main). The instruction signal Io is calculated by adding the correction signal Ic to the basic signal Ib by the adder 67.

  The command signal calculating section 61 has a limiter 68 for variably controlling the upper limit of the command signal Io. When the electric motor 17 is overheated by the limiter 68, for example, the upper limit of the command signal Io is increased. Is set lower than usual.

  The motor control unit 62 drives and controls the electric motor based on the main current value signal Imm and the command signal Io when a short-circuit diagnosis unit 69 described later determines that there is no abnormality in the control device 19. More specifically, when the control device 19 is normal, the motor control unit 62 follows the command signal Io input from the command signal calculation unit 61 with the main current value signal Imm fed back via the current detection circuit 59. Thus, the PWM command is output to the pre-driver 53.

  The fail-safe judging section 63 includes a result of a short-circuit (short-circuit) diagnosis between the first and second current detection circuits 78 and 79 described later by the short-circuit diagnosis section 69 and various sensors by the first to fourth redundancy monitoring sections 70 to 73. Judge whether or not the fail-safe processing is necessary, based on the result of the redundant comparison of the signals output by.

  The short diagnosis section 69 corresponds to the abnormality determination section of the present invention, and performs a diagnosis as part of an initial check when, for example, the ignition switch IGN-SW is turned on and the control device 19 is started. More specifically, the short diagnosis unit 69 includes a main current value signal Imm that is equal to, that is, not amplified, and a sub current value signal Ims amplified by a predetermined magnification (hereinafter, the amplified sub current value signal Ims ) Is compared with the first and second current detection circuits 78 and 79 to be described later. Then, when it is determined that a short circuit has occurred, a short determination signal Ssc indicating the short circuit is output to the fail-safe determination unit 63.

  Note that the short diagnosis section 69 does not perform the short diagnosis from the viewpoint of diagnosis accuracy when the motor current value Im is low. More specifically, when the value of the main current value signal Imm is equal to or more than a predetermined value (for example, 30 A) at which the driving of the electric motor 17 is stabilized, the short-circuit diagnosis unit 69 performs the short-circuit diagnosis. In this embodiment, the short diagnosis by the short diagnosis unit 69 is performed as part of the initial check. However, the short diagnosis may be performed periodically or constantly after the control device 19 is started.

  The first redundancy monitoring unit 70 fetches the main and sub steering angle signals θs (Main) and θs (Sub) from the first and second steering angle detection units 20a and 20b, and the absolute value | θs (Main) of the difference between them. ) −θs (Sub) | is calculated. When the absolute value | θs (Main) −θs (Sub) | is equal to or greater than a predetermined value, an abnormality has occurred in one of the main and sub steering angle signals θs (Main) and θs (Sub). As a result, the steering angle abnormality signal Ssa is output to the fail-safe determination unit 63.

  The second redundancy monitoring unit 71 takes in the main and sub torque signals Tr (Main) and Tr (Sub) from the first and second torque detection units 21a and 21b, and obtains the absolute value | Tr (Main) − of the difference between them. Tr (Sub) | is calculated. When the absolute value | Tr (Main) -Tr (Sub) | is equal to or greater than a predetermined value, an abnormality occurs in one of the main and sub torque signals Tr (Main) and Tr (Sub). And outputs the torque abnormality signal Str to the fail-safe determination unit 63.

  The third redundancy monitoring unit 72 takes in the main and sub motor rotation angle signals θm (Main) and θm (Sub) from the first and second motor rotation angle detection units 47a and 47b, and obtains the absolute value | θm of the difference between them. (Main) −θm (Sub) | is calculated. If the absolute value | θm (Main) −θm (Sub) | is equal to or greater than a predetermined value, an abnormality occurs in one of the main and sub motor rotation angle signals θm (Main) and θm (Sub). As a result, the motor rotation angle abnormality signal Sma is output to the fail-safe determination unit 63.

  The fourth redundancy monitoring unit 73 takes in the main and sub current value signals Imm and Ims from the current detection circuit 59 via the short diagnosis unit 69, and calculates the absolute value | Imm-Ims | If the absolute value | Imm-Ims | is equal to or greater than a predetermined value, it is determined that one of the main and sub current value signals Imm and Ims has failed, and the motor current value abnormality signal Smc is determined as fail-safe. Output to the unit 63.

  Further, when the short diagnosis unit 69 is performing the short diagnosis, that is, when the sub current value signal Ims is amplified, the fourth redundancy monitoring unit 73 outputs the main and sub currents from the short diagnosis unit 69. The value signals Imm and Ims are not output. Accordingly, it is possible to prevent the fourth redundancy monitoring unit 73 from making an erroneous abnormality determination based on a comparison between the main current value signal Imm that has not been amplified and the sub current value signal Ims that has been amplified. it can. In the present embodiment, as described above, the short diagnosis is performed as part of the initial check, and the short diagnosis is not performed after the control device 19 is started. Thus, the redundancy monitoring by the fourth redundancy monitoring unit 73 can be continuously performed after the activation of the control device 19.

  The fail-safe determination unit 63 needs a fail-safe process when the short-circuit determination signal Ssc, the torque abnormality signal Str, the steering angle abnormality signal Ssa, the motor rotation angle abnormality signal Sma, and the motor current value abnormality signal Smc are input. Judge. Then, a fail-safe signal Sfs indicating that fact is output to the fail-safe processing unit 64.

  Further, the fail-safe determination unit 63 is configured to receive a predetermined question from the CPU monitoring unit 57 when the CPU monitoring unit 57 determines the abnormality of the CPU 52 based on the Q & A. When the predetermined question is input, the fail-safe determination unit 63 outputs an answer to this question to the CPU monitoring unit 57.

  When the fail-safe processing unit 64 receives the fail-safe signal Sfs from the fail-safe determining unit 63, the fail-safe processing unit 64 turns on a warning light provided on an instrument panel (not shown) of the vehicle according to the situation to alert the driver. Fail-safe processing such as reducing the output of the electric motor 17 by outputting a signal to the motor control unit 62 or outputting the cutoff signal Sb to the fail-safe relay 56 is performed as appropriate.

  FIG. 5 is a diagram showing details of the inverter circuit 54 and the current detection circuit 59.

  As shown, the inverter circuit 54 is a p-channel type as three sets of switching elements that individually drive the u-phase, v-phase, and w-phase coils 26u, 26v, 26w via drive lines 74u, 74v, 74w. It has MOS-FETs 75H, 75L, 76H, 76L, 77H, 77L. The MOS-FETs 75H, 75L, 76H, 76L, 77H, and 77L are controlled on / off by the pre-driver 53 to drive the electric motor 17. Note that, as the switching element, an n-channel MOS-FET, an NPN transistor, a PNP transistor, or the like can be applied in addition to the p-channel MOS-FET described above.

  The current detection circuit 59 includes a first current detection circuit 78 through which the main current value signal Imm flows, and a second current detection circuit 79 through which the sub current value signal Ims flows. The current detection circuits 78 and 79 are arranged adjacent to each other.

  The first current detection circuit 78 includes a first amplifier 80 that is an amplitude changing unit that changes the amplitude of the main current value signal Imm, and a filter that reduces noise and the like of the main current value signal Imm passing through the first amplifier 80. And a circuit 81.

  The second current detection circuit 79 includes a second amplifier 82 that is an amplitude changing unit that changes the amplitude of the sub current value signal Imm, and a filter that reduces noise and the like of the sub current value signal Ims passing through the second amplifier 82. And a circuit 83.

  The first amplifier 80 and the second amplifier 82 are provided in a common IC (integrated circuit: Integrated Circuit) 84 with a built-in amplifier. Further, when the amplification commands AmpM and AmpS are input from the fail-safe determination unit 63 of the CPU 52, the amplifiers 80 and 82 respectively amplify the main and sub current value signals Imm and Ims to the magnifications according to the commands. It has become. The amplifiers 80 and 82 of the present embodiment can amplify the amplitudes of the main and sub current value signals Imm and Ims to 1, 2, 4 and 8 times in accordance with the amplification commands AmpM and AmpS. Is configured.

  FIGS. 6A and 6B are diagrams showing details of a short-circuit diagnosis between the first and second current detection circuits 78 and 79 by the short-circuit diagnosis unit 69, wherein FIG. 6A shows a normal state and FIG. It is.

  As shown in the figure, the amplification commands AmpM and AmpS output from the fail-safe determination unit 63 of the CPU 52 to the first and second amplifiers 80 and 82 in the short diagnosis are equal-size commands and quadruple commands, respectively. Therefore, the sub-current value signal Ims that has passed through the second amplifier 82 exhibits an output value that is approximately four times the main current value signal Imm that has passed through the first amplifier 80.

  Thus, in a state where the first and second current detection circuits 78 and 79 are not short-circuited as shown in FIG. 6A, the main and sub current value signals Imm, The difference between Ims is about three times as large as the main current value signal Imm.

  On the other hand, when a short circuit occurs downstream of the first and second amplifiers 80 and 82 as shown in FIG. 6B, the main and sub current values received by the short diagnosis unit 69 in accordance with the short circuit. The signals Imm and Ims show almost the same output value. As a result, when comparing the main and sub current value signals Imm and Ims by the short diagnosis unit 69, almost no difference is seen between the two signals Imm and Ims.

  In view of these, the short diagnosis unit 69 sets an arbitrary value less than three times the main current value signal Imm as a predetermined value (judgment threshold), and sets the absolute value | of the difference between the main and sub current value signals Imm and Ims. It is configured to determine whether there is a short circuit between the first and second current detection circuits 78 and 79 based on whether Imm-Ims | is equal to or greater than a predetermined value.

  More specifically, when the absolute value | Imm-Ims | of the difference between the main and sub current value signals Imm and Ims is equal to or greater than a predetermined value, the short-circuit diagnosis unit 69 performs the first and second current detection circuits 78 and 79. It is determined that no short circuit has occurred in between. On the other hand, if the absolute value | Imm-Ims | is less than the predetermined value, it is determined that a short circuit has occurred between the first and second current detection circuits 78 and 79.

  The predetermined value set here may be a fluctuation value that gradually increases as the motor current value Im increases, or may be a fixed value that is always constant regardless of the magnitude of the motor current value Im.

[Operation and Effect of First Embodiment]
The conventional control device detects a current value flowing through the electric motor by a current detecting resistor, and performs feedback control of the electric motor by a CPU based on a current value signal which is an analog signal of the detected current value. However, in the conventional control device, since the current value signal transmitted to the CPU is only one system, there is a case where an abnormality occurs in a circuit for transmitting the one current value signal to the CPU, for example. However, the abnormality cannot be detected.

  Therefore, in order to improve the safety of the device, in a configuration such as the conventional control device, the CPU detects the current value detected via the current detection resistor by using a two-system (double system) current value signal. A way to communicate this was considered. According to this, when an abnormality occurs in a circuit that transmits one current value signal to the CPU, the abnormality can be detected by comparing the one current value signal with the other current value signal.

  By the way, in the configuration using a dual current value signal, when an abnormality due to a short circuit occurs between the circuit of the one current value signal and the circuit of the other current value signal, the short circuit is performed. Since the two current value signals indicate substantially the same value based on the above, the abnormality cannot be detected. That is, in the configuration using the current value signal of the dual system, the abnormality can be detected when an abnormality occurs in one of the circuits by using the current value signal as the dual system. There is a problem that can not be detected.

  On the other hand, in the present embodiment, the motor current value Im is configured to be fetched into the CPU 52 as main and sub current value signals Imm and Ims, which are two-system analog signals, and when the control device 19 is started. One of the two signals Imm and Ims is taken into the CPU 52 while being amplified by the second amplifier 82, and is compared and judged by the short diagnosis unit 69. Thereby, when an abnormality based on a short circuit occurs between the first current detection circuit 78 and the second current detection circuit 79, the short circuit abnormality can be detected.

  After the control device 19 is started, the main and sub current value signals Imm and Ims that have not been amplified are taken into the CPU 52, and the two signals Imm and Ims are compared by the fourth redundancy monitoring unit 73. Accordingly, when an abnormality occurs in one of the first and second current detection circuits 78 and 79, the abnormality can be detected.

  Therefore, according to the present embodiment, an abnormality based on a failure of one of the first and second current detection circuits 78 and 79 and an abnormality based on a short circuit between the first and second current detection circuits 78 and 79 are determined. Then, fail-safe processing can be appropriately performed based on these abnormality detections. As a result, the safety of the device can be improved.

  The above operation and effect are particularly useful in a configuration in which the first current detection circuit 78 and the second current detection circuit 79 are arranged adjacent to each other as in the present embodiment.

  Further, in the present embodiment, the short-circuit diagnosis unit 69 does not perform the short-circuit diagnosis when the motor current value Im decreases in the determination accuracy, but performs the short-circuit diagnosis when the motor current value Im is equal to or more than the predetermined value. As a result, it is possible to improve the determination accuracy for the short diagnosis.

  Further, in the present embodiment, since the first and second amplifiers 80 and 82 are provided in the IC 84 with built-in amplifier, the main and sub current value signals Imm, Imm, The amplitude of Ims can be changed.

  In the present embodiment, when the short-circuit diagnosis unit 69 determines that there is no abnormality in the control device 19, the CPU 52 (motor control unit 62) basically uses a current value signal used for drive control of the electric motor 17. The main current value signal Imm in which the signal is not amplified is used. In other words, at the time of the short-circuit diagnosis, the sub-current value signal Ims not used for the drive control of the electric motor 17 is amplified. Thus, it is possible to suppress a change in the amplitude of the current value signal due to the amplification from affecting the motor control.

  In the present embodiment, the amplification commands AmpM and AmpS are set to the same and quadruple commands, respectively, in order to ensure the ease of the short diagnosis. However, if the short diagnosis can be sufficiently performed, the main and sub currents are increased. The amplification factors of the value signals Imm and Ims can be arbitrarily changed.

[Second embodiment]
In the second embodiment of the present invention shown in FIG. 7, the sub-current value signal Ims amplified by the second amplifier 82 is restored in the CPU 52 before the short-circuit diagnosis. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and a specific description thereof will be omitted.

  That is, in the CPU 52 according to the present embodiment, the main and sub current value signals Imm and Ims fetched from the first and second current detection circuits 78 and 79 are input to the first and The two converters 85 and 86 are used.

  The first and second converters 85 and 86 convert the main and sub current value signals Imm and Ims changed at a predetermined magnification by the first and second amplifiers 80 and 82 based on the amplification commands AmpM and AmpS, respectively. Change by a factor of 1 / magnification. That is, as shown in the figure, when the amplification command AmpM output from the CPU 52 to the first amplifier 80 is the same-size command, the magnification change by the first converter 85 is one (one-fold). . Further, when the amplification command AmpS output to the second amplifier 82 is a quadruple command, the magnification change by the second converter 86 is 1/4. As a result, the main and sub current value signals Imm and Ims whose amplitudes are not amplified are input to the short diagnosis section 69.

  The short-circuit diagnosis unit 69 according to the present embodiment is configured to short-circuit between the first and second current detection circuits 78 and 79 when there is a difference of a predetermined value or more between the input main and sub current value signals Imm and Ims. Is determined to have occurred.

  That is, in a state where the first and second current detection circuits 78 and 79 are not short-circuited as shown in FIG. 7A, the main and sub current value signals Imm and Ims received by the short diagnosis unit 69. Show almost the same value, so that there is almost no difference between the two signals Imm and Ims.

  On the other hand, when a short-circuit abnormality occurs downstream of the first and second amplifiers 80 and 82 as shown in FIG. 7B, the short-circuit abnormality causes input to the first and second converters 85 and 86. The main and sub current value signals Imm and Ims have substantially the same output value. In addition, since the amplitude of the sub current value signal Ims is multiplied by a factor of four by the second converter 86, the main and sub current value signals Imm and Ims received by the short diagnosis unit 69 are: A difference of about three quarters of the main current value signal Imm is seen. Based on this difference, the short-circuit diagnosis section 69 determines that a short-circuit has occurred between the first and second current detection circuits 78 and 79.

  FIG. 8 is a flowchart illustrating a process of detecting a short circuit between the first and second current detection circuits 78 and 79 by the control device 19 according to the second embodiment.

  That is, in this flow, first, it is determined whether or not the short-circuit abnormality confirmation flag Fsc is set in step S101. If the determination is Yes, it is determined that a short circuit has occurred between the first and second current detection circuits 78 and 79, and the fail-safe processing unit 64 shifts the system of the control device 19 to a safe state. Is performed (step S125). After that, a command to turn on a warning lamp arranged on an instrument panel (not shown) is output (step S126), and the program ends.

  On the other hand, if No is determined in the step S101, it is determined whether or not the short-circuit diagnosis completion flag Ff is set in a succeeding step S102. If the determination is Yes, it is determined that no short circuit has occurred between the first and second current detection circuits 78 and 79, and both the normal counter CNn and the abnormal counter CNa are cleared (steps S122 and S123). Then, after the post-amplification timer Tmr is also cleared (step S124), the program ends.

  If No is determined in step S102, the main and sub current value signals Imm and Ims are taken into the CPU 52 via the first and second current detection circuits 78 and 79 (steps S103 and S104), and then continued. It moves to step S105.

  In this step S105, it is determined whether or not the captured main current value signal Imm is equal to or more than a predetermined value Ix (for example, 30 A). If No is determined here, it is determined that it is difficult to diagnose a short circuit between the first and second current detection circuits 78 and 79, and the processes in steps S122 to S124 are performed, and then this program ends. On the other hand, if Yes is determined in step S105, it is determined that the short-circuit diagnosis between the first and second current detection circuits 78 and 79 is to be performed, and the amplitude of the sub current value signal Ims is sent from the CPU 52 to the second amplifier 82. After outputting the amplification command AmpS for amplifying by four times (step S106), the process proceeds to step S107.

  In step S107, it is determined whether a sufficient time has elapsed since the amplitude of the sub current value signal Ims was amplified. That is, in step S107, it is determined whether or not the post-amplification timer Tmr indicating the elapsed time after the amplification of the current value signal Ims is equal to or greater than a predetermined value Tx (for example, 10 ms). Here, if the determination is No, it is determined that the output of the amplified current value signal Ims is still in an unstable state, and the post-amplification timer Tmr is incremented (step S121), and then the present program is terminated. . On the other hand, if Yes is determined in step S107, it is determined that the output of the amplified current value signal Ims has become stable, and the post-amplification timer is cleared in subsequent step S108. Then, in step S109, a process of changing the amplitude of the current value signal Ims amplified by the second amplifier 82 to a quarter in the second converter 86, that is, returning the amplitude to the original amplitude of the current value signal Ims Are performed, the process proceeds to step S110.

  In step S110, it is determined whether or not the absolute value | Imm-Ims | of the difference between the main and sub current value signals Imm and Ims is equal to or greater than a predetermined value Iy (for example, 15A). If the determination is No, it is determined that there is a high possibility that a short circuit has not occurred between the first and second current detection circuits 78 and 79, and the normal counter CNn is incremented (step S111), and the abnormality counter CNa is incremented. After decrementing (step S112), the process proceeds to step S113. Then, in a step S113, it is determined whether or not the normal counter CNn is equal to or more than a predetermined value CNx (for example, a counter value for 100 ms). If the determination is No, it is highly likely that a short circuit has not occurred between the first and second current detection circuits 78 and 79, but it is determined that the short circuit diagnosis will be continued without making a final determination. Quit the program. On the other hand, if the determination is Yes, it is determined that the diagnosis result that no short circuit has occurred between the first and second current detection circuits 78 and 79 has been sufficiently accumulated, and the short-circuit diagnosis completion flag Ff is set ( (Step S114), this program ends.

  On the other hand, if it is determined in step S110 that the absolute value | Imm-Ims | is equal to or larger than the predetermined value Iy, it is determined that there is a short circuit between the first and second current detection circuits 78 and 79, and the process is continued. It moves to step S115. Then, in step S115, it is determined whether or not the accumulated abnormality counter CNa is equal to or greater than a predetermined value CNy (for example, a counter value for 10 ms). If the determination is No, the diagnosis is continued without performing the final determination, the abnormality counter CNa is incremented (step S116), and the normal counter CNn is decremented (step S117). finish. On the other hand, if Yes is determined in step S115, it is determined that a short circuit has occurred between the first and second current detection circuits 78 and 79, and the short-circuit abnormality determination flag Fsc is set (step S118). Then, the process of shifting the system of the control device 19 to the safe state is performed by the fail-safe processing unit 64 (step S119), and after outputting a command to turn on the warning lamp (step S120), the program ends.

  With this configuration, according to the control device 19 of the present embodiment, the same operation and effect as those of the first embodiment can be obtained, and the main and sub current value signals Imm and Ims of the same magnification are compared. can do. This makes it easier to set a predetermined value (judgment threshold) Iy and the like, as compared with the case where comparisons are made using current value signals Imm and Ims of different magnifications, thereby improving controllability.

  Further, according to this embodiment, the main and sub current value signals Imm and Ims at the stage when they are input to the short diagnosis unit 69 are not amplified (cancelled) in amplitude. For this reason, even during the short diagnosis, the main and sub current value signals Imm and Ims input to the short diagnosis unit 69 are output to the fourth redundancy monitoring unit 73, and the fourth redundancy monitoring unit 73 performs the redundancy monitoring. Can be.

  The present invention is not limited to the configuration of each of the above embodiments, and the configuration can be changed without departing from the spirit of the invention.

  For example, in each of the embodiments described above, an example in which the present invention is applied to a power steering device is described, but the present invention is applicable to all on-vehicle devices.

  Also, the power steering device as a vehicle-mounted device is not limited to the rack and pinion type shown in each of the above embodiments, and the present invention can be applied to a so-called integral type or column type power steering device.

  Further, in each of the above embodiments, the motor current value Im is described as an example of the state quantity of the on-vehicle equipment. However, the state quantity is not limited to this. Or a steering angle.

  As the control device of the vehicle-mounted device based on each of the embodiments described above, for example, the following devices can be considered.

  In one aspect, a control device for a vehicle-mounted device includes a CPU that calculates a command signal for controlling a driving unit of the vehicle-mounted device, a state amount detection unit that detects a state amount of the vehicle-mounted device, the CPU and the CPU. An amplitude changing section provided between the state quantity detecting sections, for changing the amplitude of a first signal which is an analog signal of the state quantity detected by the state quantity detecting section; and the amplitude changing section provided in the CPU. An abnormality judging unit that executes a comparison judgment for judging the presence or absence of an abnormality in the device by comparing the first signal that has passed through the second unit with a second signal that is an analog signal of the state quantity detected by the state quantity detecting unit. And

  In a preferred aspect of the control device for a vehicle-mounted device, the state quantity detection unit is a current sensor that detects a current value.

  In another preferred aspect, in any of the aspects of the control device for a vehicle-mounted device, the abnormality determination unit performs the comparison determination when the current value is equal to or greater than a predetermined value.

  In yet another preferred aspect, in any one of the aspects of the control device for a vehicle-mounted device, the amplitude changing unit changes the amplitude of the first signal at a predetermined magnification, and the CPU passes the amplitude changing unit. The changed first signal is changed at a magnification of 1 / predetermined magnification.

  In still another preferred aspect, in any one of the aspects of the control device for a vehicle-mounted device, the amplitude changing section is provided in an IC with a built-in amplifier.

  In still another preferred aspect, in any one of the aspects of the control device of the vehicle-mounted device, the CPU, when the abnormality determination unit determines that there is no abnormality in the device, controls the drive unit based on the second signal. Control.

  19: control device, 52: CPU, 58: current sensor (state amount detection unit), 69: short-circuit diagnosis unit (abnormality judgment unit), 82: second amplifier (amplitude change unit), Im: motor current value (state amount) ), Imm: Main current value signal (second signal), Ims: Sub current value signal (first signal), Io: Command signal

Claims (6)

A control device for a vehicle-mounted device,
A CPU for calculating a command signal for controlling a drive unit of the vehicle-mounted device;
A state quantity detection unit that detects a state quantity of the vehicle-mounted device;
An amplitude changing unit that is provided between the CPU and the state amount detection unit and changes an amplitude of a first signal that is an analog signal of the state amount detected by the state amount detection unit;
The CPU is provided to determine whether there is an abnormality in the apparatus by comparing the first signal that has passed through the amplitude change unit with a second signal that is an analog signal of the state quantity detected by the state quantity detection unit. An abnormality determination unit that performs a comparison determination for determining;
A control device for a vehicle-mounted device, comprising: The control device for a vehicle-mounted device according to claim 1,
The control device for a vehicle-mounted device, wherein the state quantity detection unit is a current sensor that detects a current value. The control device for a vehicle-mounted device according to claim 2,
The control device for a vehicle-mounted device, wherein the abnormality determination unit performs the comparison determination when the current value is equal to or greater than a predetermined value. The control device for a vehicle-mounted device according to claim 1,
The amplitude changing unit changes the amplitude of the first signal at a predetermined magnification,
The control device for a vehicle-mounted device, wherein the CPU changes the first signal that has passed through the amplitude changing unit at a magnification of the predetermined magnification. The control device for a vehicle-mounted device according to claim 1,
The control device for a vehicle-mounted device, wherein the amplitude changing unit is provided in an IC with a built-in amplifier. The control device for a vehicle-mounted device according to claim 1,
The control device for a vehicle-mounted device, wherein the CPU controls the drive unit based on the second signal when the abnormality determination unit determines that there is no abnormality in the device.

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