JP2011216683A - Solenoid driving control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solenoid driving control device with simple constitution that detects an open-circuit failure of a reflux circuit for supplying a reflux current.SOLUTION: The solenoid driving control device includes: a switching element 42b which connects or disconnects a power supply path L to a solenoid SOL by a power source BAT on a low side of the solenoid SOL; a reflux diode 42a which has an anode connected between the solenoid SOL and switching element 42b and a cathode connected between the power source BAT and solenoid SOL, and eliminates counter electromotive force generated accompanying the disconnection of the power supply path L by the switching element 42b; a low-side integrating circuit 43 which integrates a contact potential between the low side of the solenoid and switching element 42b; and a failure detection unit (CPU 41) of detecting an open-circuit failure of a parallel circuit 45 to the solenoid SOL due to the reflux diode 42a based upon a low-side integration signal as an output signal of the low-side integrating circuit 43.

Description

  The present invention relates to a solenoid drive control device.

  As a type of solenoid drive control device, one shown in Patent Document 1 is known. As shown in FIG. 1 of Patent Document 1, the solenoid drive control device includes a drive circuit 5, a CPU 6, and a monitor circuit 7. The drive circuit 5 is output via the output port 2 and the drive circuit 5 a that controls the magnitude of the drive current supplied to the connection terminal 3 of the solenoid 2 in accordance with the energization current control signal output via the output port 1. And a drive circuit 5b for controlling the return current flowing through the ground terminal 4 of the solenoid 2 in accordance with the return current control signal. The CPU 6 inputs a signal corresponding to the detection signal input to the input port to the drive circuit 5 via the output ports 1 and 2 and detects an abnormality on the connection terminal 3 side and the ground terminal 4 side according to the detection signal. The monitor circuit 7 has a first monitor threshold voltage for detecting an abnormality on the connection terminal 3 side and a second monitor threshold voltage for detecting an abnormality on the ground terminal 4 side. The monitor threshold voltage is switched between the first and second threshold voltages in accordance with the High (Hi) / Low (Lo) of the return current control signal output via the first and second threshold voltages.

  In the solenoid drive control apparatus configured as described above, the CPU 6 detects an abnormality from the output level output from the output port 1, the output level output from the output port 2, and the input signal level input to the input port. It is supposed to be.

JP 2005-248923 A

  In the solenoid drive control device described in Patent Document 1 described above, since the dedicated drive circuit 5b is provided to control the return current generated when the energization to the solenoid is stopped, the device is complicated. It was.

  Accordingly, the present invention has been made to solve the above-described problem, and an object of the present invention is to provide a solenoid drive control device having a simple configuration capable of detecting an open failure of a return circuit for supplying a return current. To do.

  In order to solve the above-mentioned problem, the structural feature of the invention according to claim 1 is that a switching element that opens or shuts off a low-side side of a solenoid in a power supply path to a solenoid by a power source, and between the solenoid and the switching element. Is applied to a solenoid driving circuit having a cathode connected between a power source and a solenoid, and a free-wheeling diode that eliminates back electromotive force due to interruption of the power supply path by the switching element, A solenoid drive control device that adjusts the power supplied to the solenoid by controlling the duty ratio, which is the ratio of the cutoff time to the unit time, by the switching element, and integrates the contact potential between the low side of the solenoid and the switching element. Low-side integrator and low-side integrator output A is based on the low side integrated signal No. is that it is a failure detecting means for detecting the open failure of the parallel circuit to the solenoid due to the return diode.

  The structural feature of the invention according to claim 2 is that, in claim 1, the steady signal level acquisition in which the signal level in a steady state where the signal level of the low-side integration signal is a value within a predetermined range is acquired as the steady signal level. The failure detection means determines whether or not the steady signal level acquired by the steady signal level acquisition means is greater than or equal to a threshold signal level that is greater than the normal value of the signal level in the steady state of the low-side integrated signal. When it is determined that the steady signal level is equal to or higher than the threshold signal level, it is detected that an open failure has occurred in the parallel circuit to the solenoid by the return diode.

  The structural feature of the invention according to claim 3 is that, in claim 2, threshold signal level setting means for setting a threshold signal level according to the duty ratio is provided.

  The structural feature of the invention according to claim 4 is that in claim 2 or claim 3, from the time when the duty ratio is changed until the low-side integrated signal that changes with the change of the duty ratio becomes a steady state. The steady time setting means for setting the steady time according to the changed duty ratio, the steady signal level acquisition means from the time when the steady time set by the steady time setting means after the change of the duty ratio has elapsed Next, in the period until the duty ratio is changed, the signal level of the low-side integration signal output from the low-side integration circuit is acquired as a steady signal level.

  A structural feature of the invention according to claim 5 is that in any one of claims 2 to 4, the time constant is the same as the time constant of the low-side integration circuit, A high-side integration circuit that integrates the side-side potential, and the failure detection means determines whether or not the steady-state signal level is equal to or higher than the threshold signal level. Is to take into account the signal level.

  The structural feature of the invention according to claim 6 is that, in any one of claims 1 to 5, the signal level of the low-side integration signal that changes with the change of the duty ratio becomes a value within a predetermined range. Based on the signal level acquired by the transient signal level acquisition means and the transient signal level acquisition means for acquiring the signal level of the low side integration signal output from the low side integration circuit in the transient state before the steady state as the transient signal level. And an actual change amount calculating means for calculating the change amount per unit time of the signal level as an actual change amount, and the failure detecting means is such that the change of the duty ratio decreases the duty ratio, and The actual change amount calculated by the actual change amount calculation means is the unit of the signal level of the low-side integrated signal in the transient state due to the change of the duty ratio. Whether or not the threshold reduction amount is smaller than the normal value of the reduction amount per hit, or the change of the duty ratio increases the duty ratio, and the actual change amount calculation means calculates It is determined whether the amount of change is equal to or greater than a threshold increase amount that is larger than the normal value of the increase amount per unit time of the signal level of the low-side integrated signal in the transient state accompanying the change of the duty ratio. When the result is affirmative, it is to detect that an open fault has occurred in the parallel circuit to the solenoid by the return diode.

  A structural feature of the invention according to claim 7 is that, in the sixth aspect, the low-side integrated signal that changes with the change of the duty ratio is changed according to the change of the duty ratio based on the changed duty ratio. Threshold change amount setting means for setting a threshold decrease amount or a threshold increase amount with respect to the changing low-side integral signal is provided.

  The structural feature of the invention according to claim 8 is that in claim 6 or claim 7, from when the duty ratio is changed, until the low-side integration signal that changes with the change of the duty ratio becomes a steady state. Transient time setting means for setting the transient time according to the duty ratio after the change, and the transient signal level acquisition means until the transient time set by the transient time setting means after the duty ratio change elapses. In this period, the signal level of the low-side integration signal output from the low-side integration circuit is acquired as a transient signal level.

  The structural feature of the invention according to claim 9 is that in any one of claims 6 to 8, the time constant is the same as the time constant of the low-side integrating circuit, A high-side integration circuit that integrates the potential on the side, and the failure detection means determines whether the actual change amount is less than or equal to the threshold decrease amount or greater than or equal to the threshold increase amount. This is to consider the signal level of the high-side integration signal that is the output signal of the integration circuit.

  In the invention according to claim 1 configured as described above, the solenoid drive control device includes a switching element that opens or closes the low-side side of the solenoid in the power supply path to the solenoid by the power source, and between the solenoid and the switching element. The anode is applied to a solenoid driving circuit including a cathode connected between a power source and a solenoid, and a free-wheeling diode that eliminates a back electromotive force associated with interruption of a power supply path by the switching element. And the duty ratio which is the ratio for the unit time of the opening time or interruption | blocking time of an electric power supply path | route is controlled by a switching element, and the electric power supplied to a solenoid is adjusted.

  Here, in the solenoid drive circuit to be controlled, if an open failure occurs in the parallel circuit to the solenoid by the freewheeling diode, flyback energy generated when the switching element is turned on and off is not consumed by the parallel circuit. The contact potential between the low side of the solenoid and the switching element changes.

  Therefore, in the invention according to claim 1, based on the low-side integration circuit that integrates the contact potential between the low-side side of the solenoid and the switching element, and the low-side integration signal that is the output signal of the low-side integration circuit, Fault detection means for detecting an open fault in the parallel circuit, and detecting an open fault in the parallel circuit with respect to the solenoid caused by the freewheeling diode based on a low side integration signal that is an output signal of the low side integration circuit.

  When an open failure occurs in the parallel circuit with respect to the solenoid by the return diode, the signal level in the steady state of the low-side integral signal becomes higher than the normal value.

  Therefore, in the invention according to claim 2 configured as described above, the signal level in a steady state where the signal level of the low-side integration signal is a value within a predetermined range is acquired as a steady signal level, and the acquired steady signal When the level is equal to or higher than a threshold signal level larger than the normal value of the signal level in the steady state of the low-side integration signal, it is detected that an open failure has occurred in the parallel circuit to the solenoid by the return diode. Thereby, in the steady state of the low-side integration signal, it is possible to detect that an open failure has occurred in the parallel circuit to the solenoid by the return diode.

  The signal level in the steady state of the low-side integration signal varies depending on the duty ratio. Therefore, in the invention according to claim 3 configured as described above, the threshold signal level is set according to the duty ratio. Thereby, the occurrence of a failure can be detected appropriately and accurately regardless of the duty ratio.

  The steady time until the low-side integrated signal is in a steady state varies depending on the duty ratio. Therefore, in the invention according to claim 4 configured as described above, the steady time from when the duty ratio is changed until the low-side integrated signal that changes along with the change of the duty ratio becomes a steady state, Set according to the changed duty ratio, and the signal level of the low-side integration signal output from the low-side integration circuit during the period from when the set steady time has elapsed until the duty ratio is next changed. , Acquired as a steady signal level. As a result, an accurate steady signal level can be acquired.

  The contact potential between the low side of the solenoid and the switching element fluctuates due to fluctuations in the output voltage of the power supply (hereinafter referred to as “power supply voltage”). Therefore, in the invention according to claim 5 configured as described above, the high-side integration circuit has a time constant similar to the time constant of the low-side integration circuit, and the potential on the high-side side of the solenoid in the power supply path. Is integrated. When determining whether or not the steady signal level is equal to or higher than the threshold signal level, the signal level of the high-side integration signal that is the output signal of the high-side integration circuit is taken into account. As a result, the phase of the voltage signal and the reference voltage signal monitored for detecting the failure can be aligned, so that the erroneous detection of the failure due to the fluctuation of the power supply voltage can be suppressed.

  When an open failure occurs in the parallel circuit to the solenoid by the freewheeling diode, the amount of decrease in the signal level per unit time in the transient state of the low-side integral signal becomes smaller than the normal value, and the unit time of the signal level in the transient state of the low-side integral signal The amount of increase per hit is greater than the normal value.

  Therefore, in the invention according to claim 6 configured as described above, the low side in the transient state before the steady state where the signal level of the low side integrated signal that changes with the change of the duty ratio becomes a value within a predetermined range is obtained. The signal level of the low-side integration signal output from the integration circuit is acquired as a transient signal level, and the amount of change per unit time of the signal level is calculated as the actual change amount based on the acquired transient signal level. I have to. Then, by comparing the calculated actual change amount with the threshold decrease amount or the threshold increase amount, it is detected that an open failure has occurred in the parallel circuit to the solenoid by the reflux diode. Thereby, it is possible to detect that an open failure has occurred in the parallel circuit to the solenoid by the return diode in the transient state of the low-side integration signal. Therefore, for example, the failure can be detected when the duty ratio is changed not only during the initial check using only the fixed duty output but also during the control of the solenoid.

  The increase / decrease amount per unit time of the signal level in the transient state accompanying the change of the duty ratio of the low-side integration signal varies depending on the changed duty ratio. Therefore, in the invention according to claim 7 configured as described above, in claim 6, the low-side integration signal that changes as the duty ratio changes is changed based on the duty ratio after the change. A threshold decrease amount or a threshold increase amount is set for the low-side integrated signal that changes with the change. Thereby, the occurrence of a failure can be detected appropriately and accurately regardless of the duty ratio.

  The transient time until the low-side integration signal becomes a steady state varies depending on the duty ratio. Therefore, in the invention according to claim 8 configured as described above, the transition time from when the duty ratio is changed to when the low-side integrated signal that changes with the change of the duty ratio becomes a steady state, The signal level of the low-side integration signal output from the low-side integration circuit is acquired as a transient signal level during a period until the set transient time elapses, according to the changed duty ratio. Thereby, an accurate transient signal level can be acquired.

  The contact potential between the low side of the solenoid and the switching element fluctuates due to fluctuations in the power supply voltage. Therefore, in the invention according to claim 9 configured as described above, the high-side integration circuit has a time constant similar to the time constant of the low-side integration circuit, and the potential on the high-side side of the solenoid in the power supply path. Is integrated. In determining whether the actual change amount is equal to or less than the threshold decrease amount or equal to or greater than the threshold increase amount, the signal level of the high-side integration signal that is the output signal of the high-side integration circuit is taken into account. I am doing so. As a result, the phase of the voltage signal and the reference voltage signal monitored for detecting the failure can be aligned, so that the erroneous detection of the failure due to the fluctuation of the power supply voltage can be suppressed.

1 is a schematic diagram showing a first embodiment of a hydraulic brake device to which a solenoid drive control device according to the present invention is applied. It is a schematic diagram which shows the electrical structure of the solenoid drive control apparatus by this invention. It is an example of a flowchart of a control program executed by the brake ECU shown in FIG. It is a figure which shows an example (when a duty ratio is 10%) of the action | operation of the solenoid drive control apparatus by this invention. It is a figure which shows an example (when a duty ratio is 90%) of the action | operation of the solenoid drive control apparatus by this invention. It is a figure which shows an example (when a duty ratio is 50%) of the action | operation of the solenoid drive control apparatus by this invention. It is an example of the flowchart which concerns on 2nd Embodiment of the control program performed in brake ECU shown in FIG. It is an example of the flowchart which concerns on 3rd Embodiment of the control program performed in brake ECU shown in FIG.

1) First Embodiment Hereinafter, a first embodiment in which a solenoid drive control device according to the present invention is applied to a hydraulic brake device will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the hydraulic brake device, and FIG. 2 is a schematic diagram showing the electrical configuration of the solenoid drive control device.

  The hydraulic brake device is for braking the vehicle. As shown in FIG. 1, each of the wheel cylinders WCfl, WCfr, WCrl, WCrr, a brake pedal 11 as a brake operation member, and a vacuum brake booster 12 , A master cylinder 13, a reservoir tank 14, a brake actuator 15 that is an automatic hydraulic pressure generator, and a brake ECU 16 that is an abnormality detection device for the electric circuit 50.

  Each wheel cylinder WCfl, WCfr, WCrl, WCrr regulates rotation of each wheel Wfl, Wfr, Wrl, Wrr, and is provided in each caliper CLfl, CLfr, CLrl, CLrr. When at least one of the basic hydraulic pressure and the control hydraulic pressure is supplied to each wheel cylinder WCfl, WCfr, WCrl, WCrr, each piston (not shown) of each wheel cylinder WCfl, WCfr, WCrl, WCrr is a friction member. A pair of brake pads (not shown) are pressed to restrict the rotation of the disc rotors DRfl, DRfr, DRrl, DRrr, which are rotating members that rotate integrally with the wheels Wfl, Wfr, Wrl, Wrr from both sides. It has become. In this embodiment, the disc type brake is adopted, but a drum type brake may be adopted.

  The vacuum brake booster 12 is a booster that boosts (increases) the brake operating force generated by depressing the brake pedal 11 by applying the intake negative pressure of the engine to the diaphragm.

  The master cylinder 13 is a device that converts the operating force of the brake pedal 11 by the driver to form a basic hydraulic pressure, and can generate a basic hydraulic braking force on the wheels Wfl, Wfr, Wrl, Wrr by the basic hydraulic pressure. In the present embodiment, the master cylinder 13 converts the brake operation force boosted by the vacuum brake booster 12 into a basic hydraulic pressure and supplies it to the wheel cylinders WCfl, WCfr, WCrl, WCrr.

  The reservoir tank 14 stores brake fluid and replenishes the master cylinder 13 with the brake fluid.

  The brake actuator 15 is provided between the master cylinder 13 and each wheel cylinder WCfl, WCfr, WCrl, WCrr, and automatically generates a control hydraulic pressure regardless of whether the brake pedal 11 is operated or not. It is a device that can be applied to WCfr, WCrl, WCrr and can generate a control hydraulic braking force on the corresponding wheels Wfl, Wfr, Wrl, Wrr.

  The configuration of the brake actuator 15 will be described in detail with reference to FIG. The brake actuator 15 is composed of a plurality of systems that are hydraulic circuits that operate independently. Specifically, the brake actuator 15 has a first system 15a and a second system 15b that are X pipes. The first system 15a communicates the first hydraulic chamber 13a of the master cylinder 13 with the left rear wheel Wrl and the wheel cylinders WCrl and WCfr of the right front wheel Wfr to control the braking force of the left rear wheel Wrl and the right front wheel Wfr. It is a system concerning. The second system 15b communicates the second hydraulic chamber 13b of the master cylinder 13 with the left front wheel Wfl and the wheel cylinders WCfl and WCrr of the right rear wheel Wrr, respectively, and controls the braking force of the left front wheel Wfl and the right rear wheel Wrr. It is a system concerning.

  The first system 15 a includes a differential pressure control valve 21, a left rear wheel hydraulic pressure control unit 22, a right front wheel hydraulic pressure control unit 23, and a first pressure reduction unit 24.

  The differential pressure control valve 21 is a normally open linear solenoid valve (normally disposed between the master cylinder 13 and the upstream portion of the left rear wheel hydraulic pressure control unit 22 and the upstream portion of the right front wheel hydraulic pressure control unit 23. Open linear solenoid valve). The differential pressure control valve 21 is controlled to be switched between a communication state (non-differential pressure state) and a differential pressure state by the brake ECU 16. Although the differential pressure control valve 21 is not energized and is in a normal communication state, the hydraulic pressure on the wheel cylinders WCrl, WCfr side is changed to the hydraulic pressure on the master cylinder 13 side by energizing to the differential pressure state (closed side). The pressure can be kept higher than the predetermined control differential pressure. This control differential pressure is regulated by the brake ECU 16 in accordance with the control current. Thus, a control hydraulic pressure corresponding to the control differential pressure is formed on the premise of pressurization by the pumps 24a and 34a.

  The left rear wheel hydraulic pressure control unit 22 can control the hydraulic pressure supplied to the wheel cylinder WCrl, and is a two-port two-position switching type normally open electromagnetic on-off valve 22a and a two-port two-position switching type. And a pressure reducing valve 22b which is a normally closed electromagnetic on-off valve. The pressure increasing valve 22a is interposed between the differential pressure control valve 21 and the wheel cylinder WCrl, and can communicate or block the differential pressure control valve 21 and the wheel cylinder WCrl in accordance with a command from the brake ECU 16. . The pressure reducing valve 22b is interposed between the wheel cylinder WCrl and the pressure regulating reservoir 24c, and can communicate or block the wheel cylinder WCrl and the pressure regulating reservoir 24c in accordance with a command from the brake ECU 16. As a result, the hydraulic pressure in the wheel cylinder WCrl can be increased, held and reduced.

  The right front wheel hydraulic pressure control unit 23 can control the hydraulic pressure supplied to the wheel cylinder WCfr, and includes a pressure increasing valve 23 a and a pressure reducing valve 23 b as with the left rear wheel hydraulic pressure control unit 22. The pressure increasing valve 23a and the pressure reducing valve 23b are controlled by a command from the brake ECU 16, so that the hydraulic pressure in the wheel cylinder WCfr can be increased, held, and reduced.

  The first pressure reducing unit 24 includes a pump 24a, a pump motor 24b, and a pressure regulating reservoir 24c. The pump 24a pumps up the brake fluid in the pressure regulating reservoir 24c and supplies the brake fluid between the differential pressure control valve 21 and the pressure increasing valves 22a and 23a. The pump 24a is driven by a pump motor 24b that is driven in accordance with a command from the brake ECU 16.

  The pressure regulating reservoir 24c is a device that temporarily accumulates brake fluid extracted from the wheel cylinders WCrl and WCfr via the pressure reducing valves 22b and 23b. Further, the pressure regulating reservoir 24c communicates with the master cylinder 13, and when the brake fluid in the pressure regulating reservoir 24c is equal to or less than a predetermined amount, the brake fluid is supplied from the master cylinder 13 while the predetermined amount. In the case of more, the supply of brake fluid from the master cylinder 13 is stopped.

  Thereby, when a differential pressure state is formed by the differential pressure control valve 21 and the pump 24a is driven (for example, in the case of side slip prevention control, traction control, etc.), the brake fluid supplied from the master cylinder 13 is discharged. The pressure can be supplied to the upstream side of the pressure increasing valves 22a and 23a via the pressure regulating reservoir 24c.

  The second system 15 b includes a differential pressure control valve 31, a left front wheel hydraulic pressure control unit 32, a right rear wheel hydraulic pressure control unit 33, and a second pressure reducing unit 34.

  The differential pressure control valve 31 is a normally open linear solenoid valve interposed between the master cylinder 13 and the upstream part of the left front wheel hydraulic pressure control unit 32 and the upstream part of the right rear wheel hydraulic pressure control unit 33. . In the same manner as the differential pressure control valve 21, the differential pressure control valve 31 is a pressure that is higher by the brake ECU 16 than the hydraulic pressure on the master cylinder 13 side by the hydraulic pressure on the wheel cylinders WCfl, WCrr side by a predetermined control differential pressure. Can be retained.

  The left front wheel hydraulic pressure control unit 32 and the right rear wheel hydraulic pressure control unit 33 can control the hydraulic pressure supplied to the wheel cylinders WCfl and WCrr, respectively. The pressure increase valve 32a and the pressure reduction valve 32b, and the pressure increase valve 33a and the pressure reduction valve 33b are comprised. The pressure-increasing valve 32a and the pressure-reducing valve 32b, and the pressure-increasing valve 33a and the pressure-reducing valve 33b are respectively controlled by commands from the brake ECU 16, so that the hydraulic pressure in the wheel cylinder WCfl and the wheel cylinder WCrr can be increased, held, and reduced, respectively. It has become.

  Similar to the first decompression unit 24, the second decompression unit 34 includes a pump 34a, a pump motor 24b (shared with the first decompression unit 24), and a pressure regulating reservoir 34c. The pump 34a pumps up brake fluid in a pressure regulating reservoir 34c similar to the pressure regulating reservoir 24c, and supplies the brake fluid between the differential pressure control valve 31 and the pressure increasing valves 32a, 33a. The pump 34a is driven by a pump motor 24b that is driven in accordance with a command from the brake ECU 16.

  In the brake actuator 15 configured in this way, all the solenoid valves are de-energized during normal braking, and the brake hydraulic pressure corresponding to the operating force of the brake pedal 11, that is, the basic hydraulic pressure is set to the wheel cylinder WC. Each can be supplied to **. In addition, ** is a subscript corresponding to each ring and is any one of fl, fr, rl, and rr, and indicates left front, right front, left rear, and right rear. The same applies to the following description and drawings.

  Further, when the pump motor 24b, that is, the pumps 24a and 34a is driven and the differential pressure control valves 21 and 31 are excited, the brake hydraulic pressure obtained by adding the control hydraulic pressure to the basic hydraulic pressure from the master cylinder 13 is set to the wheel cylinder WC **. Can be supplied to each.

  Further, the brake actuator 15 can individually adjust the hydraulic pressure of the wheel cylinder WC ** by controlling the pressure increasing valves 22a, 23a, 32a, 33a and the pressure reducing valves 22b, 23b, 32b, 33b. . Thereby, according to instructions from the brake ECU 16, for example, well-known anti-skid control, front / rear braking force distribution control, side slip prevention control that is ESC (Electronic Stability Control) (specifically, understeer suppression control, oversteer suppression control), Traction control, inter-vehicle distance control, etc. can be achieved.

  In addition, the hydraulic brake device includes wheel speed sensors Sfl, Sfr, Srl, Srr. Wheel speed sensors Sfl, Sfr, Srl, Srr are provided in the vicinity of each wheel Wfl, Wfr, Wrl, Wrr, and brake a pulse signal having a frequency according to the rotation of each wheel Wfl, Wfr, Wrl, Wrr. It is output to the ECU 16.

  As shown in FIG. 2, the brake ECU 16 that is a solenoid drive control device includes a CPU 41, a solenoid drive circuit 42, a first monitor circuit 43, and a second monitor circuit 44. The brake ECU 16 adjusts the power supplied to the solenoid SOL by controlling the duty ratio, which is the ratio of the opening time or the cutoff time of the power supply path L to the unit time, by the switching element 42b.

  The CPU 41 is a solenoid valve to be controlled, that is, a solenoid corresponding to the solenoid valve, command information to the solenoid (control type information such as linear current control, on / off control, on / off time (duty ratio) information, etc.). A drive request is output to the solenoid drive unit 42c. Further, the CPU 41 inputs an integration signal output from the first and second monitor circuits 43 and 44.

  The solenoid drive circuit 42 includes a battery BAT, a solenoid SOL, a reflux diode 42a, and a switching element 42b.

  The battery BAT is a DC power source, for example. The solenoid SOL indicates only one solenoid SOL among the solenoids of the solenoid valves 21, 31, 22a, 22b, 23a, 23b, 32a, 32b, 33a, 33b described above, and a solenoid for driving the solenoid SOL. Only the drive circuit 42 is shown, and other solenoids and their solenoid drive circuits are omitted.

  The reflux diode 42a has an anode connected between the solenoid SOL and the switching element 42b, and a cathode connected between the positive electrode of the battery BAT and the solenoid SOL. The freewheeling diode 42a consumes a flyback current generated when the current supplied to the solenoid SOL is cut off, that is, eliminates the back electromotive force.

  The parallel circuit 45 is a parallel circuit for the solenoid SOL, and includes a freewheeling diode 42a.

  The switching element 42b is provided on the low side of the solenoid SOL in the power supply path L to the solenoid SOL by the battery BAT, and opens or shuts off the power supply path L. The switching element 42b is composed of, for example, a MOSFET (MOS field effect transistor). The switching element 42b includes a switching unit 42b1 and a diode unit 42b2. The drain (input end) of the switching unit 42b1 is connected to the low-side end of the solenoid SOL. The source (output terminal) of the switching unit 42b1 is grounded (connected to the negative electrode of the battery BAT). A gate (signal input terminal) of the switching unit 42b1 is connected to an output port (not shown) of the solenoid driving unit 42c. The cathode of the diode part 42b2 is connected to the drain of the switching part 42b1, and the anode is connected to the source of the switching part 42b1. Therefore, the switching element 42b also has a function of allowing only a current flowing from the output end side to the input end side.

  The solenoid drive unit 42c performs on / off control of a drive current applied to the solenoid SOL to be controlled in response to a drive request from the CPU 41. The solenoid drive unit 42c transmits an on / off signal corresponding to a drive request command from the CPU 41 to the switching element 42b to control energization / non-energization of the solenoid SOL.

  The first monitor circuit 43 is a circuit for monitoring the voltage on the low side of the solenoid SOL. The first monitor circuit 43 is a low side integration circuit that integrates the contact potential between the low side of the solenoid SOL and the switching element 42b. Specifically, the first monitor circuit 43 includes a resistor 43a, a resistor 43b, and a capacitor 43c. The resistors 43a and 43b are used to divide the contact potential between the low side of the solenoid SOL and the switching element 42b, and are set to resistance values that can be monitored by the CPU 41.

  Resistor 43a and capacitor 43c act as an RC integrating circuit. The relationship between the input voltage Vin and the output voltage Vout when the switching element 42b is on is expressed by the following equation 1, and the relationship between the input voltage Vin and the output voltage Vout when the switching device 42b is off is expressed by the following equation 2.

(Equation 1)
Vout = Vin × (Rb / (Ra + Rb)) × e ^{(−t / RC)}
(Equation 2)
Vout = Vin * (Rb / (Ra + Rb)) * (1-e ^{(-t / RC)} )

Here, Ra is the resistance value of the resistor 43a, Rb is the resistance value of the resistor 43b, and C is the capacitance of the capacitor 43c.
Further, the time constant τ of this integrating circuit is RC.

  The second monitor circuit 44 is a circuit for monitoring the voltage supplied from the battery BAT to the solenoid SOL, that is, the reference voltage. The second monitor circuit 44 is a high-side integration circuit that integrates the high-side potential of the solenoid in the power supply path L supplied from the battery BAT to the solenoid SOL. Specifically, the second monitor circuit 44 includes a resistor 44a, a resistor 44b, and a capacitor 44c. The resistors 44a and 44b are used to divide the voltage of the battery BAT, and are set to resistance values that can be monitored by the CPU 41. The resistance values of the resistors 44a and 44b are the same as the resistance values of the resistors 43a and 43b, and the capacitance of the capacitor 44c is the same as the capacitance of the capacitor 43c.

  Resistor 44a and capacitor 44c act as an RC integrating circuit. Also in this integration circuit, the time constant is the same as that of the first monitor circuit 43.

  Next, an example of failure determination of the return diode 42a at the initial check of the normally open valve (hereinafter, abbreviated as NO valve) of the solenoid drive control device described above will be described with reference to the flowchart of FIG. When an ignition switch (not shown) of the vehicle is turned on, the brake ECU 16 executes a program corresponding to the above flowchart. When the brake ECU 16 is activated, the brake ECU 16 determines whether or not the NO valve initial check flag is turned on (step 102). The NO valve initial check flag is a flag indicating whether or not an initial check is necessary, and indicates that it is necessary for “ON”, and indicates that it is not necessary for “OFF”. The NO valve initial check flag is turned on when the brake ECU 16 is activated.

  If the NO valve initial check flag is on, the brake ECU 16 performs an initial check. If it is off, the initial check is not executed and the flowchart of FIG. 3 is terminated.

  At the initial check, the brake ECU 16 determines whether or not the steady signal level is equal to or higher than a threshold signal level that is greater than the normal value of the signal level in the steady state of the low-side integral signal, and the steady signal level is the threshold signal level. When it determines with it being above, it detects that the open failure has generate | occur | produced in the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a. The open fault of the parallel circuit 45 includes an open fault of the freewheeling diode 42a itself, a connection failure of the connection terminal of the warm current diode 42a, and the like.

  Specifically, the brake ECU 16 sets the drive duty ratio of the solenoid SOL to 50% (step 104). Thereby, the solenoid SOL starts on / off control with a duty ratio of 50%.

  Next, the brake ECU 16 acquires the steady signal level Vst after the steady time Tst has elapsed (steps 106 and 108). Specifically, the brake ECU 16 starts from the first monitor circuit 43 when the steady time Tst has elapsed from the time when a drive request is made at a drive duty ratio of 50% (when drive control is started at a duty ratio of 50%). The signal level of the input low-side integration signal is acquired as the steady signal level Vst (step 108).

  The steady signal level Vst is a signal level in a steady state where the signal level of the low-side integrated signal input from the first monitor circuit 43 is a value within a predetermined range. The steady state is a state in which a change in signal level has settled after a predetermined time (for example, the steady time Tst) has elapsed since the start of duty drive control.

  Further, the brake ECU 16 compares the steady signal level Vst with the threshold signal level Vth to detect whether or not an open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. Specifically, the brake ECU 16 determines whether or not the steady signal level Vst acquired in step 108 is equal to or higher than the threshold signal level Vth (step 110).

  The threshold signal level Vth is set to a value larger than the normal value of the signal level in the steady state of the low-side integrated signal. Specifically, the threshold signal level Vth is obtained by adding the predetermined value α to the duty ratio set in step 104 to the signal level Vhi of the high-side integration signal input from the second monitor circuit 44. The value is set to be multiplied (Vth = Vhi × (duty ratio + α)). Thus, the threshold signal level Vth is set according to the duty ratio.

  This is because when the switching element 42b is off, the high-side integration signal and the low-side integration signal are the common voltage (Vhi = Vst), and the high-side side is calculated as the reference voltage. Further, the predetermined value α is a voltage fluctuation caused by charging / discharging of the capacitor in the circuit due to the on / off duty of the switching element 42b input to the low side integration signal, and a circuit (resistor, capacitor) of the low side integration signal and the high side integration signal It is set from the initial value due to temperature, and the value taking into account variations due to temperature and deterioration.

  If the steady signal level Vst is equal to or higher than the threshold signal level Vth, the brake ECU 16 determines “YES” in step 110, and an open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. Is detected. Then, the brake ECU 16 performs a failure process such as issuing a warning indicating a failure (step 112). Thereafter, the brake ECU 16 sets the NO valve initial check flag to OFF and ends the program (step 114).

  If the steady signal level Vst is less than the threshold signal level Vth, the brake ECU 16 makes a “NO” determination at step 110, and no open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. Is detected. Thereafter, the brake ECU 16 sets the NO valve initial check flag to OFF (step 114) and ends the program.

  Here, as described above, the reason why an open failure can be detected by using the low-side integration signal will be described.

  When the duty ratio is set to 10%, the case where the return diode 42a is normal and the case where an open failure occurs will be described with reference to FIG. The upper part shows the on / off signal input to the switching element 42b, the middle part shows the downstream voltage of the solenoid SOL, and the lower part shows the low-side integration signal input to the CPU 41.

  Since the duty ratio is 10%, the opening time (on time) is 10%, and the cutoff time (off time) is 90%.

  When the return diode 42a is normal, the back electromotive force generated when the switching element 42b is turned off from the on state is eliminated by the flyback current passing through the return diode 42a. Therefore, the downstream voltage of the solenoid SOL is equal to GND because it is grounded via the switching element 42b when the switching element 42b is on, and is connected to the positive electrode of the battery BAT via the solenoid SOL when it is off. + B).

  Furthermore, when starting the duty drive control for the switching element 42b that has been in the off state, the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c is just before the switching element 42b is off. Is equipotential with the battery voltage. Next, when the switching element 42b is turned on, since the connection potential between the resistor 43a and the capacitor 43c is + B as described above and is higher than the downstream voltage (GND) of the solenoid SOL, the capacitor 43c is discharged. Therefore, the connection potential between the resistor 43a and the capacitor 43c decreases while the switching element 42b is turned on. Next, when the switching element 42b is turned off, the connection potential between the resistor 43a and the capacitor 43c is lower than the downstream voltage (+ B) of the solenoid SOL, so that the capacitor 43c is charged. Therefore, the connection potential between the resistor 43a and the capacitor 43c increases while the switching element 42b is turned on.

  As described above, when the switching element 42b is repeatedly turned on and off, as shown by the solid line in the lower part of FIG. 4, the low-side integration signal decreases and converges as a whole while decreasing and increasing.

  On the other hand, when the freewheeling diode 42a has an open failure, the counter electromotive force generated when the switching element 42b is turned off is not eliminated because the flyback current does not pass through the freewheeling diode 42a. Therefore, the downstream voltage of the solenoid SOL is equal to GND because it is grounded via the switching element 42b when the switching element 42b is on, and is connected to the positive electrode of the battery BAT via the solenoid SOL when it is off. + B) is a potential obtained by adding a back electromotive voltage (indicated by a broken line in the middle of FIG. 4).

  Furthermore, when starting the duty drive for the switching element 42b in the off state, the connection potential (low-side integration signal) of the resistor 43a and the capacitor 43c is off immediately before the start, so the switching element 42b is off. It is equipotential with the battery voltage. Next, when the switching element 42b is turned on, the connection potential between the resistor 43a and the capacitor 43c becomes + B and is higher than the downstream voltage (GND) of the solenoid SOL, so that the capacitor 43c is discharged. Therefore, the connection potential between the resistor 43a and the capacitor 43c decreases while the switching element 42b is turned on. Next, when the switching element 42b is turned off, the connection potential between the resistor 43a and the capacitor 43c is higher by the counter electromotive voltage than the downstream voltage (+ B) of the solenoid SOL. Charged extra. Therefore, the connection potential between the resistor 43a and the capacitor 43c is further increased as compared with the normal time while the switching element 42b is turned off (indicated by a broken line in the lower part of FIG. 4).

  Thus, when the switching element 42b is on, the low-side integration signal decreases at the time of failure as in the normal state. On the other hand, at the time of OFF, the amount of increase is larger by the amount of flyback energy than at the time of failure. Therefore, when ON / OFF is repeatedly performed, as indicated by a broken line in the lower part of FIG. 4, the low-side integration signal converges while repeating increase / decrease as in the normal state. The convergence value is larger than that in a normal state and is larger than the threshold signal level Vth.

  As described above, when the free-wheeling diode 42a is normal, the convergence value is smaller when the low-side integrated signal is in a steady state than when it is a failure. The inventor of the present application pays attention to this, and finds that the failure of the parallel circuit 45 is detected by comparing the steady-state low-side integration signal, that is, the steady-state signal level Vst and the threshold signal level Vth.

  Next, when the duty ratio is set to 90%, the case where the return diode 42a is normal and the case where an open failure occurs will be described with reference to FIG. The upper part shows the on / off signal input to the switching element 42b, the middle part shows the downstream voltage of the solenoid SOL, and the lower part shows the low-side integration signal.

  Since the duty ratio is 90%, the opening time (on time) is 90%, and the cutoff time (off time) is 10%.

  When the free-wheeling diode 42a is normal and the duty ratio is 10%, when the switching element 42b is turned on, the on-time becomes longer and the discharge time from the capacitor 43c becomes longer, so that the resistors 43a and 43c The voltage drop amount of the connection potential (low side integration signal) increases. Further, when the switching element 42b is turned off, the difference in connection potential between the resistor 43a and the capacitor 43c does not become relatively large because the off time of the switching element 42b is short. Therefore, as with the duty ratio of 10%, the voltage of the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c increases, but the increase amount is small.

  As described above, when the switching element 42b is repeatedly turned on and off, as shown by the solid line in the lower part of FIG. 5, the low-side integration signal decreases and increases as a whole and converges. The convergence value is a small value compared to the case of 10%.

  On the other hand, when the return diode 42a has an open failure, when the switching element 42b is on, the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c is the same as when the return diode 42a is normal. Further, when the switching element 42b is turned off, the difference in connection potential between the resistor 43a and the capacitor 43c increases by the amount of flyback energy. However, since the switching element 42b has a short off time and is turned on while flyback energy is generated, the difference between the connection potentials of the resistor 43a and the capacitor 43c is not relatively large as compared with the case where the freewheeling diode 42a is normal. . Therefore, as with the duty ratio of 10%, the voltage of the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c increases, but the increase amount is small.

  Therefore, as in the case where the duty ratio is 10%, when the ON / OFF operation is repeated, the low-side integration signal converges while repeating the increase / decrease as in the normal state as shown by the broken line in the lower part of FIG. . The convergence value is larger than that in a normal state and is larger than the threshold signal level Vth.

  Furthermore, when the duty ratio is set to 50%, the case where the freewheeling diode 42a is normal and the case where there is an open failure will be described with reference to FIG. The upper part shows the on / off signal input to the switching element 42b, the middle part shows the downstream voltage of the solenoid SOL, and the lower part shows the low-side integration signal.

  Since the duty ratio is 50%, both the opening time (on time) and the cutoff time (off time) are 50%.

  When the free-wheeling diode 42a is normal and the duty ratio is 10%, when the switching element 42b is turned on, the on-time becomes longer and the discharge time from the capacitor 43c becomes longer, so that the resistors 43a and 43c The voltage drop amount of the connection potential (low side integration signal) increases. Compared with the case where the duty ratio is 90%, the voltage drop amount decreases.

  Further, when the switching element 42b is turned off, the switching element 42b can be kept off for a relatively long time, so that the difference in connection potential between the resistor 43a and the capacitor 43c can be made relatively large. Therefore, as with the duty ratio of 10%, the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c increases, but the increase amount is large.

  As described above, when the switching element 42b is repeatedly turned on and off, as shown by the solid line in the lower part of FIG. 6, the low-side integration signal decreases and increases as a whole and converges. The convergence value is a small value compared to the case where the duty ratio is 10% and a large value compared to the case where the duty ratio is 90%.

  On the other hand, when the return diode 42a has an open failure, when the switching element 42b is on, the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c is the same as when the return diode 42a is normal.

  Further, when the switching element 42b is turned off, the switching element 42b can be secured for a long time and is turned on again after the completion of the flyback energy, so that a certain amount of flyback energy can be obtained. Further, since a certain amount of off-time until re-on can be ensured, the difference in connection potential between the resistor 43a and the capacitor 43c can be made relatively large as compared with the case where the free wheel diode 42a is normal. Therefore, the connection potential (low-side integration signal) between the resistor 43a and the capacitor 43c has a larger voltage increase than the duty ratio of 10% or 90%.

  Therefore, as in the case where the duty ratio is 10%, when the ON / OFF operation is repeated, the low-side integration signal converges while repeating the increase / decrease as in the normal state as shown by the broken line in the lower part of FIG. . The convergence value is larger than that in a normal state and is larger than the threshold signal level Vth. In addition, the difference between the low-side integrated signal at normal time and the low-side integrated signal at open failure is larger than when the duty ratio is 10% or 90%.

  As is apparent from the above description, according to the present embodiment, the solenoid drive control device (brake ECU 16) opens the low side of the solenoid SOL in the power supply path L to the solenoid SOL by the power source (battery BAT). Alternatively, an anode is connected between the switching element 42b to be cut off, the solenoid SOL and the switching element 42b, and a cathode is connected between the power source (battery BAT) and the solenoid SOL, and the back electromotive force caused by the interruption of the power supply path L by the switching element 42b. The present invention is applied to a solenoid drive circuit 42 that includes a free-wheeling diode 42a that eliminates electric power. Then, the switching element 42b controls the duty ratio, which is the ratio of the power supply path L to the opening / closing time or the unit time, to adjust the power supplied to the solenoid SOL.

  Here, in the solenoid drive circuit 42 to be controlled, when an open failure occurs in the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a, flyback energy generated when the switching element 42b is turned on / off is converted into the parallel circuit 45. Therefore, the contact potential between the low side of the solenoid SOL and the switching element 42b changes.

  Therefore, according to the present embodiment, the output of the low side integration circuit (first monitor circuit 43) that integrates the contact potential between the low side of the solenoid SOL and the switching element 42b, and the output of the low side integration circuit (first monitor circuit 43). A failure detection means (CPU 41) for detecting an open failure of the parallel circuit 45 with respect to the solenoid SOL by the free-wheeling diode 42a based on the low-side integration signal as a signal; and an output signal of the low-side integration circuit (first monitor circuit 43) Based on a certain low-side integration signal, an open failure of the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a is detected. Therefore, it is possible to provide a solenoid drive control device having a simple configuration capable of detecting an open failure of a return circuit for supplying a return current.

  Further, when an open failure occurs in the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a, the signal level in the steady state of the low-side integral signal becomes higher than the normal value. Therefore, in the present embodiment, the signal level in a steady state where the signal level of the low-side integration signal is a value within a predetermined range is acquired as a steady signal level (steady signal level acquisition means, step 108), and the acquired steady signal When the level is equal to or higher than the threshold signal level larger than the normal value of the signal level in the steady state of the low-side integration signal, it is detected that an open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. (Failure detection means, step 110). Thereby, in the steady state of the low-side integration signal, it is possible to detect that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a.

  Further, the signal level in the steady state of the low-side integration signal varies depending on the duty ratio. Therefore, in this embodiment, the threshold signal level is set according to the duty ratio (threshold signal level setting means, step 110). Thereby, the occurrence of a failure can be detected appropriately and accurately regardless of the duty ratio.

  Further, the contact potential between the low side of the solenoid SOL and the switching element 42b fluctuates due to fluctuations in battery voltage (power supply voltage). Therefore, in the present embodiment, the high-side integration circuit (second monitor circuit 44) has a time constant similar to that of the low-side integration circuit (first monitor circuit 43), and the solenoid SOL in the power supply path L. The potential on the high side is integrated. When determining whether or not the steady signal level is equal to or higher than the threshold signal level, the signal level of the high-side integration signal that is the output signal of the high-side integration circuit (second monitor circuit 44) is taken into account. (Failure detection means, step 110). As a result, the phase of the voltage signal and the reference voltage signal monitored for detecting the failure can be aligned, so that the erroneous detection of the failure due to the fluctuation of the battery power supply can be suppressed.

2) Second Embodiment Next, a second embodiment in which the solenoid drive control device according to the present invention is applied to a hydraulic brake device will be described with reference to FIG. FIG. 7 shows an example of determining an open failure of the return diode 42a when the solenoid drive control device (brake ECU 16) shifts to, for example, the ABS pressure reduction mode other than the initial check.

  When an ignition switch (not shown) of the vehicle is turned on, the brake ECU 16 executes a program corresponding to the above flowchart. When the brake ECU 16 is activated, the brake ECU 16 determines whether or not the NO valve check flag is turned on (step 202), as in step 102 described above. The NO valve check flag is turned on when the brake ECU 16 is activated or whenever ABS control is started.

  If the NO valve check flag is on, the brake ECU 16 performs a NO valve check in step 206 and subsequent steps. If it is off, the NO valve check is not executed and the flowchart of FIG. 7 is terminated.

  When the NO valve is checked, the brake ECU 16 determines that the actual change amount calculated based on the transient signal level is equal to or less than the threshold decrease amount when the change of the duty ratio is to decrease the duty ratio. Alternatively, when the change of the duty ratio is to increase the duty ratio, if it is determined that the actual change amount is equal to or greater than the threshold increase amount, an open failure occurs in the parallel circuit 45 to the solenoid SOL by the freewheeling diode 42a. Detect what is happening.

  Specifically, when the brake ECU 16 shifts to the ABS pressure reduction mode, the brake ECU 16 determines “YES” in step 204, and the low side input from the first monitor circuit 43 at the time of shift (duty ratio change time). The signal level of the integrated signal is acquired as the transient signal level Vtr1 (transient signal level acquisition means, step 206).

  The brake ECU 16 also closes the NO valve by changing the duty ratio of the NO valve from 0% to 90%.

  Next, the brake ECU 16 acquires the transient signal level Vtr2 after a predetermined time T1 has elapsed (steps 208 and 210). Specifically, the brake ECU 16 starts to count the elapsed time Tp1 that has elapsed since the time when the brake ECU 16 shifted to the decompression mode, and when the elapsed time Tp1 has passed the predetermined time T1 (when determined “YES” in step 208) At that time, the signal level of the low-side integration signal input from the first monitor circuit 43 is acquired as the transient signal level Vtr2 (transient signal level acquisition means, step 210).

  The transient signal levels Vtr1 and Vtr2 are obtained from the first monitor circuit 43 in a transient state before the steady state (described above) in which the signal level of the low-side integrated signal that changes with the change of the duty ratio becomes a value within a predetermined range. This is the signal level of the output low-side integration signal.

  Further, the brake ECU 16 calculates the amount of change per unit time of the signal level of the low-side integral signal as the actual change amount ΔVtr based on the transient signal levels Vtr1 and Vtr2 (actual change amount calculating means, step 212). Specifically, the brake ECU 16 acquires a value obtained by subtracting the transient signal level Vtr2 from the transient signal level Vtr1 as the actual change amount ΔVtr.

  Further, the brake ECU 16 compares the actual change amount ΔVtr with the threshold change amount ΔVth to detect whether or not an open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. Specifically, the brake ECU 16 determines whether or not the actual change amount ΔVtr acquired in step 212 is equal to or less than the threshold change amount ΔVth (step 214).

  The threshold change amount ΔVth is a threshold change amount that is smaller than the normal value of the change amount per unit time of the signal level of the low-side integrated signal in the transient state accompanying the change of the duty ratio. In step 214, the threshold change amount ΔVth for the low-side integration signal that changes with the change of the duty ratio is set for the low-side integration signal that changes with the change of the duty ratio, based on the changed duty ratio. (Threshold change amount setting means).

For example, the threshold change amount ΔVth can be set as a value obtained by subtracting the threshold value Vth2 at the time of acquiring the transient signal level Vtr2 from the threshold value Vth1 at the time of acquiring the transient signal level Vtr1. The threshold value Vth1 and the threshold value Vth2 are the voltage Vth (= V _th−1 × e ^{(−ton / τ)} ) during the on-time during duty drive control and the voltage Vth (= ( Vhi−V _th−1 ) × e ^{(−toff / τ)} + V _th−1 ). For example, the average value of the voltage Vth during a predetermined period may be calculated based on the voltage Vth during the on-time during duty drive control and the voltage Vth during the off-time during duty drive control, and when the transient signal level Vtr1 is acquired. An average value of the voltage Vth during a predetermined period including may be calculated.

Here, ton is the on-time, toff is the off-time, τ is the time constant of the low-side integration circuit, and V _th−1 is the voltage during the on-time during the previous duty drive control and the off during the duty drive control. It is the voltage in time. Vhi is an input voltage (= battery voltage × resistance value of resistor 44b / (resistance value of resistor 44a + resistance value of resistor 44b)) of the high-side integration circuit. The voltage Vth when the duty drive is off is battery voltage × resistance value of the resistor 43b / (resistance value of the resistor 43a + resistance value of the resistor 43b). The voltage division ratio and time constant of the high side integration circuit and the low side integration circuit are the same.

  If the actual change amount ΔVtr is less than or equal to the threshold change amount ΔVth, the brake ECU 16 determines “YES” in step 214, and an open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. Is detected. Then, the brake ECU 16 performs a failure process such as issuing a warning indicating a failure (step 216). Thereafter, the brake ECU 16 sets the NO valve check flag to OFF and ends this program (step 218).

  If the actual change amount ΔVtr is larger than the threshold change amount ΔVth, the brake ECU 16 makes a “NO” determination at step 214 to indicate that no open failure has occurred in the parallel circuit 45 to the solenoid SOL by the return diode 42a. To detect. Thereafter, the brake ECU 16 sets the NO valve check flag to OFF (step 218) and ends the program.

  By the way, when an open failure occurs in the parallel circuit 45 with respect to the solenoid SOL by the freewheeling diode 42b, the decrease amount per unit time of the signal level in the transient state of the low-side integral signal becomes smaller than the normal value, and in the transient state of the low-side integral signal. The amount of increase in signal level per unit time is larger than the normal value.

  Therefore, as described above, according to the present embodiment, the low-side integration circuit 43 is in a transient state before the steady state in which the signal level of the low-side integration signal that changes with the change of the duty ratio becomes a value within a predetermined range. Is acquired as a transient signal level (transient signal level acquisition means, steps 206 and 210), and based on the acquired transient signal level, the signal level per unit time is acquired. The change amount is calculated as the actual change amount (actual change amount calculating means, step 212). Then, by comparing the calculated actual change amount with the threshold decrease amount or the threshold increase amount, it is detected that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the reflux diode 42a. (Failure detection means, step 214). Thus, it is possible to detect that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the free-wheeling diode 42a in the transient state of the low-side integration signal. Therefore, for example, the failure can be detected when the duty ratio is changed not only during the initial check using only the fixed duty output but also during the control of the solenoid.

  Further, the amount of increase or decrease of the signal level per unit time in the transient state accompanying the change of the duty ratio of the low-side integration signal varies depending on the changed duty ratio. Therefore, according to the present embodiment, with respect to the low-side integration signal that changes with the change of the duty ratio, the threshold reduction with respect to the low-side integration signal that changes with the change of the duty ratio is based on the duty ratio after the change. An amount or threshold increase amount is set (threshold change amount setting means, step 214). Thereby, the occurrence of a failure can be detected appropriately and accurately regardless of the duty ratio.

  Further, the contact potential between the low side of the solenoid SOL and the switching element 42b fluctuates due to the fluctuation of the battery voltage. Therefore, in the present embodiment, the high side integration circuit 44 has a time constant similar to the time constant of the low side integration circuit 43, and integrates the potential on the high side of the solenoid SOL in the power supply path. . Then, in determining whether the actual change amount is equal to or less than the threshold decrease amount or greater than the threshold increase amount, the signal level of the high side integration signal that is the output signal of the high side integration circuit 44 is taken into account. Like to do. As a result, the phase of the voltage signal and the reference voltage signal that are monitored to detect the failure can be aligned, so that the erroneous detection of the failure due to the fluctuation of the battery voltage can be suppressed.

3) Third Embodiment Next, a third embodiment in which the solenoid drive control device according to the present invention is applied to a hydraulic brake device will be described with reference to FIG. FIG. 8 shows an example in which the solenoid drive control device (brake ECU 16) determines an open failure of the return diode 42a when, for example, the duty ratio is changed in addition to the initial check.

  When an ignition switch (not shown) of the vehicle is turned on, the brake ECU 16 executes a program corresponding to the above flowchart. When the duty ratio is changed, the brake ECU 16 starts measuring the elapsed time Tp from the time of the change (step 302).

  Then, the brake ECU 16 determines whether or not the normal close valve (for example, the pressure reducing valve 32b) check flag is turned on, as in step 202 described above (step 304). If the NO valve check flag is on, the brake ECU 16 performs a NO valve check in step 306 and thereafter. If it is off, the flowchart of FIG. 8 is terminated without executing the NO valve check.

  The brake ECU 16 sets the transient time Ttr based on the current duty ratio (step 306), and detects the failure based on the transient signal level and the failure detection based on the steady signal level according to the elapsed time from the duty ratio change. Selectively. That is, before the elapsed time Tp passes the transient time Ttr (determined as “YES” in step 308), the brake ECU 16 performs failure detection based on the transient signal level (steps 310 to 326), and the elapsed time Tp. After the transition time Ttr has elapsed (determined as “NO” in step 308), failure detection based on the steady signal level (steps 330 to 342, 326) is performed. The transient time is the time until the steady state is reached after the duty ratio is changed.

  First, failure detection based on the transient signal level will be described. The brake ECU 16 acquires the signal level of the low-side integration signal input from the first monitor circuit 43 as the transient signal level Vtr1 at the time of changing the duty ratio (transient signal level acquisition means, step 310).

  Further, the brake ECU 16 acquires the transient signal level Vtr2 after the predetermined time T1 has elapsed (steps 312 and 314). Specifically, the brake ECU 16 starts measuring the elapsed time Tp that has elapsed since the duty ratio was changed, and when the elapsed time Tp has passed the predetermined time T1 (when “YES” is determined in step 312). At that time, the signal level of the low-side integration signal input from the first monitor circuit 43 is acquired as the transient signal level Vtr2 (transient signal level acquisition means, step 314).

  Further, the brake ECU 16 calculates the amount of change per unit time of the signal level of the low-side integrated signal as the actual change amount ΔVtr based on the transient signal levels Vtr1 and Vtr2 (actual change amount calculating means, step 316). Specifically, the brake ECU 16 acquires a value obtained by subtracting the transient signal level Vtr2 from the transient signal level Vtr1 as the actual change amount ΔVtr.

  Further, the brake ECU 16 sets the threshold change amount ΔVth based on the current duty ratio and the elapsed time Tp (step 318). That is, the brake ECU 16 determines, based on the duty ratio after the change, the threshold reduction amount with respect to the low-side integration signal that changes with the change of the duty ratio or the above-described low-side integration signal that changes with the change of the duty ratio. A threshold increase amount is set (threshold change amount setting means).

  Furthermore, when the brake ECU 16 determines that the actual change amount calculated based on the transient signal level is equal to or less than the threshold reduction amount when the change of the duty ratio is to decrease the duty ratio, It is detected that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the diode 42a (steps 320 and 322). In other cases, it is detected that no failure has occurred.

  Alternatively, when the change in the duty ratio is to increase the duty ratio, the brake ECU 16 determines that the actual change amount is equal to or greater than the threshold increase amount, and the parallel circuit 45 for the solenoid SOL by the return diode 42a. It is detected that an open failure has occurred (steps 320 and 324). In other cases, it is detected that no failure has occurred.

  In step 320, it is determined whether or not the duty ratio change is to decrease the duty ratio (whether or not the change amount ΔVtr> 0). In step 322, it is determined whether or not the absolute value of the change amount ΔVtr is equal to or less than the threshold decrease amount ΔVthd1. In step 324, it is determined whether or not the absolute value of the change amount ΔVtr is equal to or greater than the threshold increase amount ΔVthu1.

  The threshold decrease amount ΔVthd1 and the threshold increase amount ΔVthu1 are set in the same manner as the threshold change amount ΔVth described above. The threshold decrease amount ΔVthd1 is a value smaller than the normal value of the decrease amount per unit time of the signal level of the low-side integrated signal in the transient state accompanying the change of the duty ratio. The threshold increase amount ΔVthu1 is a value larger than the normal value of the increase amount per unit time of the signal level of the low-side integrated signal in the transient state accompanying the change of the duty ratio.

  If a failure is detected, the brake ECU 16 performs a failure process such as issuing a warning indicating a failure (step 326). Thereafter, the brake ECU 16 sets the NO valve check flag to OFF and ends the program (step 328). On the other hand, if no failure is detected, the brake ECU 16 sets the NO valve check flag to OFF (step 328) and ends the program.

  Next, failure detection based on the steady signal level will be described. The brake ECU 16 acquires the signal level of the low-side integration signal input from the first monitor circuit 43 as the steady signal level Vst1 when the duty ratio is changed (steady signal level acquisition means, step 330).

  Further, the brake ECU 16 acquires the transient signal level Vtr2 after the steady time Tst (described above) has elapsed (steps 332 and 334). Specifically, the brake ECU 16 starts counting the elapsed time Tp that has elapsed since the duty ratio was changed, and when the elapsed time Tp has passed the steady time Tst (when determined “YES” in step 332). At that time, the signal level of the low-side integration signal input from the first monitor circuit 43 is acquired as the steady signal level Vst2 (steady signal level acquisition means, step 334).

  Further, the brake ECU 16 calculates the amount of change per unit time of the signal level of the low-side integral signal as the actual change amount ΔVst based on the steady signal levels Vst1 and Vst2 (actual change amount calculating means, step 336). Specifically, the brake ECU 16 acquires a value obtained by subtracting the steady signal level Vst2 from the steady signal level Vst1 as the actual change amount ΔVst.

  Further, the brake ECU 16 sets the threshold signal level Vth based on the current duty ratio (threshold signal level setting means, step 338). The threshold signal level Vth is set in the same manner as in step 110 described above. Further, the brake ECU 16 sets the threshold increase amount ΔVthu2 based on the current duty ratio and the elapsed time Tp (step 338). That is, the brake ECU 16 sets a threshold increase amount for the low-side integration signal that changes with the change of the duty ratio, based on the changed duty ratio, for the low-side integration signal that changes with the change of the duty ratio. (Threshold change amount setting means).

  Further, the brake ECU 16 determines that the signal level Vst2 of the low-side integral signal in the steady state is larger than the threshold signal level Vth, or the signal level change amount ΔVst of the low-side integral signal in the steady state is larger than the threshold increase amount ΔVthu2. If larger, it is detected that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the return diode 42a (steps 320 and 322). In other cases, it is detected that no failure has occurred.

  In step 340, it is determined whether or not the steady signal level Vst2 is greater than the threshold signal level Vth. In step 342, it is determined whether or not the change amount ΔVst is larger than the threshold increase amount ΔVthu2. The threshold increase amount ΔVthu2 is set in the same manner as the threshold increase amount ΔVthu1 described above. The threshold increase amount ΔVthu2 is a value larger than the normal value of the increase amount per unit time of the signal level of the low-side integrated signal in the steady state.

  If a failure is detected, the brake ECU 16 performs a failure process such as issuing a warning indicating a failure (step 326). Thereafter, the brake ECU 16 sets the NO valve check flag to OFF and ends the program (step 328). On the other hand, if no failure is detected, the brake ECU 16 sets the NO valve check flag to OFF (step 328) and ends the program.

  By the way, the steady time until the low-side integrated signal is in a steady state varies depending on the duty ratio. Therefore, as described above, according to the present embodiment, the steady time from when the duty ratio is changed until the low-side integrated signal that changes with the change of the duty ratio becomes a steady state is changed to the value after the change. Is set in accordance with the duty ratio (steady time setting means, step 306), and the low side output from the low side integration circuit in the period from when the set steady time has elapsed until the next duty ratio is changed. The signal level of the integrated signal is acquired as a steady signal level (steady signal level acquisition means, steps 330 and 334). As a result, an accurate steady signal level can be acquired.

  Further, when an open failure occurs in the parallel circuit 45 to the solenoid SOL by the freewheeling diode 42a, the decrease amount per unit time of the signal level in the transient state of the low-side integral signal becomes smaller than the normal value, and the transient state of the low-side integral signal The amount of increase in signal level per unit time is larger than the normal value.

  Therefore, according to the present embodiment, the low side output from the low side integration circuit 43 in the transient state before the steady state where the signal level of the low side integration signal that changes with the change of the duty ratio becomes a value within a predetermined range. The signal level of the integrated signal is acquired as a transient signal level (transient signal level acquisition means, steps 310 and 314), and the amount of change per unit time of the signal level is actually changed based on the acquired transient signal level. It is calculated as an amount (actual change amount calculating means, step 316). Then, by comparing the calculated actual change amount with the threshold decrease amount or the threshold increase amount, it is detected that an open failure has occurred in the parallel circuit to the solenoid by the return diode (failure detection). Means, steps 320-324). Thus, it is possible to detect that an open failure has occurred in the parallel circuit 45 with respect to the solenoid SOL by the free-wheeling diode 42a in the transient state of the low-side integration signal. Therefore, for example, the failure can be detected when the duty ratio is changed not only during the initial check using only the fixed duty output but also during the control of the solenoid SOL.

  Further, the amount of increase or decrease of the signal level per unit time in the transient state accompanying the change of the duty ratio of the low-side integration signal varies depending on the changed duty ratio. Therefore, according to the present embodiment, with respect to the low-side integration signal that changes with the change of the duty ratio, the threshold reduction with respect to the low-side integration signal that changes with the change of the duty ratio is based on the duty ratio after the change. The amount or the threshold increase amount is set (threshold change amount setting means, step 318). Thereby, the occurrence of a failure can be detected appropriately and accurately regardless of the duty ratio.

  In addition, the transition time until the low-side integration signal becomes a steady state varies depending on the duty ratio. Therefore, according to this embodiment, the transition time from when the duty ratio is changed until the low-side integrated signal that changes with the change of the duty ratio becomes a steady state is determined according to the changed duty ratio. Set (transient time setting means, step 306), and acquire the signal level of the low-side integration signal output from the low-side integration circuit as the transient signal level during the period until the set transient time elapses (transient signal level) Acquisition means, steps 310, 314). Thereby, an accurate transient signal level can be acquired.

  Further, the contact potential between the low side of the solenoid SOL and the switching element 42b fluctuates due to fluctuations in the power supply voltage. Therefore, according to the present embodiment, the high side integration circuit 44 has a time constant similar to the time constant of the low side integration circuit 43 and integrates the potential on the high side of the solenoid SOL in the power supply path L. I have to. In determining whether the actual change amount is equal to or less than the threshold decrease amount or equal to or greater than the threshold increase amount, the signal level of the high-side integration signal that is the output signal of the high-side integration circuit is taken into account. I am doing so. As a result, the phase of the voltage signal and the reference voltage signal that are monitored to detect the failure can be aligned, so that the erroneous detection of the failure due to the fluctuation of the battery voltage can be suppressed.

  In the above-described embodiment, the switching element 42b may be provided on the high side of the solenoid SOL.

  The present invention can also be applied to solenoids other than the solenoid of the NO valve constituting the brake actuator.

  DESCRIPTION OF SYMBOLS 11 ... Brake pedal, 12 ... Vacuum-type brake booster, 13 ... Master cylinder, 14 ... Reservoir tank, 15 ... Brake actuator, 16 ... Brake ECU (solenoid drive control device), 21, 31 ... Differential pressure control valve (linear) Solenoid valve), 22 ... left rear wheel hydraulic pressure control unit, 23 ... right front wheel hydraulic pressure control unit, 24 ... first pressure reducing unit, 32 ... left front wheel hydraulic pressure control unit, 33 ... right rear wheel hydraulic pressure control unit, 34 ... 2nd decompression part, 41 ... CPU, 42 ... Solenoid drive circuit, 42a ... Freewheeling diode, 42b ... Switching element, 43 ... 1st monitor circuit (low side integration circuit), 44 ... 2nd monitor circuit (high side integration circuit) 45 ... Parallel circuit, BAT ... Battery (power source), SOL ... Solenoid, L ... Power supply path, Wfl, Wfr, Wrl, Wrr ... Wheel, Sfl, Sfr, Srl Srr ... wheel speed sensor, WCfl, WCfr, WCrl, WCrr ... wheel cylinder.

Claims (9)

Of the power supply path (L) to the solenoid (SOL) by the power source (BAT), the switching element (42b) for opening or closing the low side of the solenoid, and the anode between the solenoid and the switching element are connected to the power source And a cathode connected between the solenoids and applied to a solenoid drive circuit (42) comprising a return diode (42a) for eliminating a counter electromotive force caused by the interruption of the power supply path by the switching element,
A solenoid drive control device that adjusts the power supplied to the solenoid by controlling a duty ratio, which is a ratio of a unit time of an opening time or a cutoff time of the power supply path, by the switching element;
A low side integration circuit (43) for integrating a contact potential between the low side of the solenoid and the switching element;
Solenoid comprising failure detection means (16, 41) for detecting an open failure of a parallel circuit with respect to the solenoid by the reflux diode based on a low side integration signal which is an output signal of the low side integration circuit Drive control device. In Claim 1, the steady signal level acquisition means (16, step 108, 330, 334) which acquires the said signal level in the steady state in which the signal level of the said low side integration signal becomes a value within a predetermined range as a steady signal level. Prepared,
In the failure detection means (16, 41, steps 110, 340, 342), the steady signal level acquired by the steady signal level acquisition means is larger than the normal value of the signal level in the steady state of the low-side integral signal. When it is determined whether or not the threshold signal level is greater than or equal to the threshold signal level, an open fault has occurred in the parallel circuit to the solenoid by the return diode. Solenoid drive control device characterized by detecting   3. The solenoid drive control device according to claim 2, further comprising threshold signal level setting means (16, 41, steps 110, 338) for setting the threshold signal level according to the duty ratio. The steady state time from when the duty ratio is changed until the low-side integrated signal that changes with the change of the duty ratio becomes the steady state is the duty after the change. A stationary time setting means (16, 41, step 306) for setting according to the ratio;
The steady signal level acquisition means (16, 41, step 338) is in a period from the time when the steady time set by the steady time setting means has elapsed after the change of the duty ratio to the next change of the duty ratio. A solenoid drive control device that acquires the signal level of the low-side integration signal output from the low-side integration circuit as the steady-state signal level. In any one of Claims 2 thru | or 4,
A time constant similar to the time constant of the low side integration circuit, and a high side integration circuit (44) for integrating the high side potential of the solenoid in the power supply path,
The failure detection means (16, 41, steps 110, 340, 342) determines whether the steady signal level is equal to or higher than the threshold signal level. A solenoid drive control device characterized by taking into account the signal level of an integral signal. In any one of Claims 1 to 5,
The signal level of the low-side integration signal output from the low-side integration circuit in the transient state before the steady state where the signal level of the low-side integration signal that changes with the change of the duty ratio becomes a value within a predetermined range is set. Transient signal level acquisition means (16, 41, steps 206, 210, 310, 314) for acquiring as a transient signal level;
Based on the signal level acquired by the transient signal level acquisition means, actual change amount calculation means (16, 41, steps 212, 316) for calculating a change amount per unit time of the signal level as an actual change amount; With
In the failure detection means (16, 41, steps 214, 320-324), the change of the duty ratio decreases the duty ratio, and the actual change amount calculated by the actual change amount calculation means is Whether the signal level of the low-side integrated signal in the transient state associated with the change of the duty ratio is equal to or less than a threshold reduction amount smaller than a normal value of the reduction amount per unit time, or the change of the duty ratio is The duty ratio is increased, and the actual change amount calculated by the actual change amount calculating means is an increase per unit time of the signal level of the low-side integrated signal in a transient state accompanying the change of the duty ratio. It is determined whether or not the threshold increase amount is greater than the normal value of the amount, and when the determination result is affirmative, Solenoid drive control apparatus characterized by detecting that the open failure has occurred in the parallel circuit of diode for the solenoid.   7. The threshold for the low-side integration signal that changes with the change of the duty ratio, based on the duty ratio after the change, for the low-side integration signal that changes with the change of the duty ratio. A solenoid drive control device comprising threshold change amount setting means (16, 41, step 318) for setting a decrease amount or the threshold increase amount. The transient time from when the duty ratio is changed to when the low-side integrated signal that changes as the duty ratio changes becomes the steady state according to claim 6 or claim 7. A transient time setting means (16, 41, step 306) for setting according to the ratio;
The transient signal level acquisition means (16, 41, steps 310, 314) is output from the low-side integration circuit during a period until the transient time set by the transient time setting means elapses after the duty ratio is changed. A solenoid drive control device that acquires the signal level of the low-side integration signal as the transient signal level. In any one of Claims 6 to 8,
A time constant similar to the time constant of the low side integration circuit, and a high side integration circuit (44) for integrating the high side potential of the solenoid in the power supply path,
The failure detection means (16, 41, step 318) determines whether the actual change amount is less than or equal to the threshold decrease amount or greater than or equal to the threshold increase amount. A solenoid drive control device characterized by taking into account the signal level of a high-side integration signal that is an output signal of a circuit.

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