JP2013216308A - Electric steering lock device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric steering lock device configured to respond to a failure of a switching element constituting an H-bridge circuit.SOLUTION: When switching elements H1, H2 of four switching elements H1, H2, L1, L2 constituting an H-bridge circuit 3 are turned on, a motor 2 is rotated in a forward direction to lock a steering lock. The switching elements H2, L1 are turned on, the motor 2 is rotated in a reverse direction to release the steering lock. When an ON-failure is detected in any of the switching elements H1, H2, L1, and L2, a switching element on the same potential side as the faulty element is ON-controlled.

Description

  The present invention relates to an electric steering lock device that drives and drives a driving source with an H-type bridge circuit to lock and release a steering lock.

  Patent Document 1 discloses a technique for driving a motor by an H-type bridge circuit. In this technique, an example in which an H-type bridge circuit is configured in the manner shown in FIG. 7 and the steering lock motor is driven by the H-type bridge circuit is illustrated here. In this case, when the high-potential side switching element H1 and the low-potential side switching element L2 form a pair, and both the elements H1 and L2 are turned on, the steering lock motor is rotated in the forward direction. At this time, the lock bar is fitted with the lock holder, and the steering lock is locked. As a result, steering cannot be performed. On the other hand, when the high-potential side switching element H2 and the low-potential side switching element L1 form a pair and both the elements H2 and L1 are turned on, the steering lock motor is rotated in the reverse direction. At this time, the lock bar is disengaged and the steering lock is released. As a result, steering can be performed.

JP 2001-206236 A (paragraph [0002])

  By the way, when two of the four switching elements constituting the H-type bridge circuit are both turned ON, the steering lock is locked or released at a timing different from the original control timing.

  The present invention has been made paying attention to such problems, and an object thereof is to provide an electric steering lock device capable of dealing with a failure of a switching element constituting an H-type bridge circuit. It is in.

  In order to achieve the above object, the invention described in claim 1 is an electric steering lock device that locks and releases a steering lock by driving a drive source with an H-type bridge circuit. Failure detecting means for detecting the presence or absence of an ON failure of the four switching elements, and switching control means for ON-controlling the switching element on the same potential side as the switching element in which the ON failure is detected by the failure detecting means. This is the gist.

  According to the same configuration, when an ON failure of any of the four switching elements constituting the H-type bridge circuit is detected, the switching element on the same potential side as that element is ON-controlled, so that the drive source is locked. It becomes. Thereby, the state of the steering lock is maintained in the same state as before the ON failure of the switching element. That is, the steering lock is prevented from being released from the locked state or locked from the released state at a timing different from the original control timing. Therefore, it is possible to cope with a failure of the switching element constituting the H-type bridge circuit.

  According to a second aspect of the present invention, in the electric steering lock device according to the first aspect, the power supply line for the drive source is a power supply that cuts off the power supply to the drive source when the H-type bridge circuit is short-circuited. The gist is that a blocking means is provided.

  When an ON failure is detected in any of the four switching elements constituting the H-type bridge circuit, the switching element on the same potential side as that element is ON-controlled as in the configuration of claim 1. If, in this state, the “specific switching element” defined below among the four switching elements constituting the H-type bridge circuit fails to ON, a short circuit will occur in the H-type bridge circuit. According to the second aspect of the present invention, the supply of power to the drive source is interrupted by the power supply interrupting means in accordance with this short circuit. Therefore, since the drive source is surely locked, the steering lock state can be reliably maintained in the same state as before the switching element is turned on.

  The “specific switching element” is defined as follows. First, out of the four switching elements constituting the H-type bridge circuit, both the switching element in which the ON failure is detected and the switching element on the same potential side as the element are excluded from the definition target. That is, two switching elements on the potential side different from the two elements are to be defined. Of the two switching elements on the different potential side, a switching element that drives the drive source in the forward or reverse direction together with the switching element in which the ON failure is detected is defined as a “specific switching element”. Is done.

  According to a third aspect of the present invention, in the electric steering lock device according to the first or second aspect, the failure detection means includes two switching elements on the high potential side among the four switching elements constituting the H-type bridge circuit. When an element is to be detected for the presence or absence of an ON failure, it is determined that there is an ON failure of the switching element on the condition that the potential of the connection node of the switching element with respect to the drive source is fixed at the high potential. In addition, when two switching elements on the low potential side among the four switching elements constituting the H-type bridge circuit are to be detected as to whether there is an ON failure, the potential of the connection node of the switching element with respect to the drive source is Determining that there is an ON failure of the switching element on the condition that it is fixed at the low potential. It is the gist.

  According to the same configuration, the potential of the connection node with respect to the drive source of each switching element is monitored, and if the potential is fixed at the same potential as that during ON control at a timing different from the original control timing, there is an ON failure. It is determined. Therefore, it is possible to accurately determine the ON failure of the switching element.

  According to a fourth aspect of the present invention, in the electric steering lock device according to any one of the first to third aspects, the switching control means detects an ON failure of one of the switching elements by the failure detection means. In this case, the gist is to prohibit the driving of the driving source by the H-type bridge circuit.

  According to this configuration, when an ON failure of any switching element is detected, driving of the drive source by the H-type bridge circuit is prohibited. Thereby, when the ON failure of the switching element is detected before the vehicle travels, the steering lock can be maintained in the locked state. Therefore, in this case, it is possible to prevent the vehicle from traveling while the switching element is in the ON failure state.

  According to a fifth aspect of the present invention, in the electric steering lock device according to any one of the second to fourth aspects of the present invention, the power supply shut-off means is caused by an element being blown by a short-circuit current associated with a short circuit of the H-type bridge circuit. The main point is that it is a fuse.

  According to this configuration, when the H-bridge circuit is short-circuited, the fuse element is blown, so that the power supply to the drive source is reliably cut off without being controlled by the switching control means. Therefore, the drive source is reliably maintained in the locked state, and thereby the state transition of the steering lock can be surely prevented.

  According to a sixth aspect of the present invention, there is provided an electric steering lock device that locks and releases a steering lock by driving a driving source by an H-type bridge circuit, and the H-type bridge circuit has an H A failure detection means for detecting the presence or absence of an ON failure in the switching element constituting the H-type bridge circuit and the short-circuit prevention element, provided with a short-circuit prevention element which is a switching element for preventing a short-circuit of the type bridge circuit; And a switching control means for controlling ON of the switching element on the same potential side as the switching element in which the ON failure is detected when the ON failure of the switching element constituting the H-type bridge circuit is detected by the means. It is said.

  According to the same configuration, when an ON failure of a switching element constituting the H-type bridge circuit is detected, the switching element on the same potential side as that element is controlled to be ON, so that the drive source is locked and the steering lock Can be reliably maintained in the same state as before the failure, and the short circuit of the H type bridge circuit due to the double failure with the switching element on the different potential side constituting the H type bridge circuit by providing the short circuit prevention element. Can be prevented. Therefore, it is possible to cope with a failure of the switching element constituting the H-type bridge circuit.

  According to a seventh aspect of the present invention, in the electric steering lock device according to the sixth aspect, the switching control means drives the drive source when an ON failure of the short-circuit prevention element is detected by the failure detection means. Then, the gist is to turn on the switching elements constituting the H-type bridge circuit on the side where the steering lock is released.

  According to the same configuration, when an ON failure of the short-circuit prevention element is detected during traveling of the vehicle, among the switching elements constituting the H-type bridge circuit, the switching element on the side that releases the steering lock is ON-controlled, When a triple failure occurs with the two switching elements on the side that locks the steering lock, the drive source is locked, and the steering lock can be reliably maintained in the same released state as before the failure.

  According to an eighth aspect of the present invention, in the electric steering lock device according to the sixth or seventh aspect, the switching control means detects an ON failure of any switching element or the short-circuit prevention element by the failure detection means. In this case, the gist is to prohibit the driving of the driving source by the H-type bridge circuit.

  According to this configuration, when an ON failure of any switching element or short-circuit prevention element is detected in the parking state before the vehicle travels, driving of the drive source by the H-type bridge circuit is prohibited. As a result, the steering lock can be maintained in the locked state. Therefore, in this case, it is possible to prevent the vehicle from traveling while the switching element or the short-circuit prevention element constituting the H-type bridge circuit remains ON.

  ADVANTAGE OF THE INVENTION According to this invention, it can respond to the failure of the switching element which comprises an H-type bridge circuit.

The electric circuit diagram which shows the principal part structure of the steering lock electronic control apparatus which drive-controls the motor with which this electric steering lock apparatus is provided about 1st Embodiment of the electric steering lock apparatus which concerns on this invention. The table | surface which shows an example of the failure determination by a microcomputer. The electric circuit diagram which shows the principal part structure of sterol ECU about 2nd Embodiment. The table | surface which shows an example of the failure determination by a microcomputer. The electric circuit diagram which shows the principal part structure of sterol ECU about 3rd Embodiment. The table | surface which shows an example of the failure determination by a microcomputer. The electric circuit diagram which shows the example of a drive of the steering lock motor by an H type bridge circuit.

(First embodiment)
Hereinafter, a first embodiment of an electric steering lock device according to the present invention will be described. This electric steering lock device includes a steering lock motor as a drive source, and a lock bar that receives a driving force from the motor and that can be displaced over a lock position where the lock holder is engaged and a release position where the engagement is released. I have. When the lock bar is in the locked position, the steering lock is locked, and steering cannot be performed. On the other hand, when the lock bar assumes the release position, the steering lock is released, and steering can be performed. The steering lock motor is a DC motor that can rotate in both the forward and reverse directions under the control of a microcomputer provided in a steering lock electronic control unit (STERO ECU: Electronic Control Unit).

  As shown in FIG. 1, the steering ECU 1 is provided with an H-type bridge circuit 3 that drives a motor 2. The H-type bridge circuit 3 includes a switching element H1 that is disposed on the high potential side and connected to the first end of the motor 2, and a switching element H2 that is disposed on the high potential side and connected to the second end of the motor 2. The switching element L1 is connected to the first end of the motor 2 while being arranged on the low potential side, and the switching element L2 is connected to the second end of the motor 2 while being arranged on the low potential side.

  Among these elements, the high-potential side elements H1 and H2 are each composed of a P-channel power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), and each drain is connected to the motor 2 and each source is connected to each other. It is connected to the + terminal of the + B power source through one fuse F. That is, a fuse F is provided on the power supply line for the motor 2. On the other hand, each of the low-potential side elements L1 and L2 is composed of an N-channel power MOSFET, and each drain is connected to the motor 2 and each source is grounded. The gates of the elements H1, H2, L1, and L2 are connected to the microcomputer 10.

  The microcomputer 10 drives the motor 2 by the H-type bridge circuit 3 by controlling the gate voltages of the elements H1, H2, L1, and L2. More specifically, when the microcomputer 10 rotates the motor 2 in the forward direction, the gate voltage of the high-potential side element H1 is set to the L level while the gate voltage of the high-potential side element H1 is set to the L level. By setting the gate voltage of the element L2 to the H level, both the elements H1 and L2 are turned on. At this time, a current flows from the first end portion to the second end portion of the motor 2, whereby the motor 2 is rotated in the forward direction, and the lock bar takes the locking position. On the other hand, when the microcomputer 10 rotates the motor 2 in the opposite direction, the low-potential side element L1 is set while setting the gate voltage of the high-potential side element H2 to the L level for the pair of the two switching elements H2 and L1. Both of the elements H2 and L1 are turned ON by setting the gate voltage of H2 to H level. At this time, a current flows from the second end portion to the first end portion of the motor 2, whereby the motor 2 is rotated in the reverse direction and the lock bar takes the release position.

  A monitor terminal a is set at the first end of the motor 2 via a 5V circuit, and a monitor terminal b is also set at the second end of the motor 2. The microcomputer 10 monitors the potentials of the monitor terminals a and b, analyzes the monitoring results, detects the presence / absence of an ON failure in each of the elements H1, H2, L1, and L2, and further detects the detection results. Accordingly, ON / OFF control of each element is performed.

Here, a method for determining ON failure will be described.
As shown in FIG. 2, when the switching element L1 is determined as an ON failure determination target, the potential of the monitor terminal a is referred to. 2, when the potential of the monitor terminal “a” is at the GND level, the ON state of the switching element L1 is grasped. In this case, the microcomputer 10 controls the element L1 to be ON. It is determined that there is an ON failure except for. That is, if the drain potential of the switching element L1 is fixed at the same GND potential as that during ON control at a timing different from the original control timing, it is determined that there is an ON failure of the element L1. As shown in the second stage of FIG. 2, when the potential of the monitor terminal a is at the 5V level, or as shown in the third stage of FIG. 2, the potential of the monitor terminal a is at the + B level. It is determined that there is no ON failure of the switching element L1.

  When the switching elements H1, L2, and H2 are determined as ON failure determination targets, the ON failure of each element is determined based on the same principle as described above. Although details are omitted, it is determined that there is an ON failure of the switching element H1 when the potential of the monitor terminal a is at the + B level, and there is an ON failure of the switching element L2 when the potential of the monitor terminal b is at the GND level. When the potential of the monitor terminal b is at the + B level, it is determined that there is an ON failure of the switching element H2 (see FIG. 2).

Next, the operation of the electric steering lock device will be described.
When the vehicle is parked, the steering lock is locked. In this state, the microcomputer 10 determines whether or not each element H1, H2, L1, L2 has an ON failure in the manner shown in FIG. If it is determined that there is no ON failure for all the elements, the steering lock is released on condition that a regular electronic key suitable for the vehicle exists in the vehicle. That is, in this case, both the elements H2 and L1 are controlled to be turned ON by the microcomputer 10, whereby the motor 2 is rotated in the reverse direction and the lock bar takes the release position. As a result, upon completion of the release of the steering lock, the engine is started and the vehicle can travel.

  The failure determination by the microcomputer 10 is continued even while the vehicle is traveling. For example, if it is determined that there is an ON failure of the element H1, the microcomputer 10 controls the element H2 on the same potential side as the element H1. Then, since the electric potentials at both ends of the motor 2 become substantially the same + B level, the motor 2 is locked. As a result, the steering lock state is maintained in the same released state as before the ON failure of the element H1. As a result, the steering lock is prevented from being locked while the vehicle is traveling.

  In the state where the element H2 is ON-controlled in response to the ON failure of the element H1 while the vehicle is running, if the element L2 that is paired with the element H1 is ON-failed, both the elements H2 and L2 are turned ON. A short circuit occurs in the type bridge circuit 3. In this case, the element of the fuse F is blown by the short-circuit current, whereby the power supply itself to the motor 2 is cut off. As a result, the steering lock is reliably maintained in the released state.

  Incidentally, when it is determined that there is an ON failure of the element L2 while the vehicle is running, the element L1 is ON-controlled based on the same principle as described above. Then, since the electric potentials at both ends of the motor 2 become substantially the same GND level, the motor 2 is locked. As a result, the steering lock is maintained in the released state. In this state, when the element H1 is turned ON and a short circuit occurs in the H-type bridge circuit 3, the fuse F is blown and the power supply to the motor 2 is cut off. As a result, the steering lock is reliably maintained in the released state. .

  By the way, when the ON failure of any element is detected in the parking state before the vehicle travels, the driving of the motor 2 by the H-type bridge circuit 3 is prohibited. For example, if it is determined that there is an ON failure of the element H1, the element H2 is ON-controlled in the same manner as described above, whereby the steering lock is maintained in the locked state. As a result, the engine is not started.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When an ON failure of any of the four switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3 is detected, the switching element on the same potential side as that element is controlled to be ON. The motor 2 is locked. Thereby, the state of the steering lock is maintained in the same state as before the ON failure of the switching element. That is, the steering lock is prevented from being released from the locked state or locked from the released state at a timing different from the original control timing. Therefore, it is possible to cope with a failure of the switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3.

  (2) For example, when the element L2 that is paired with the element H1 is ON-failed in a state where the element H2 is ON-controlled in response to the ON failure of the element H1 while the vehicle is running, a short circuit occurs in the H-type bridge circuit 3 In this case, however, the fuse F is blown by the short-circuit current, whereby the power supply to the motor 2 is cut off. Therefore, since the motor 2 is surely locked, the steering lock state can be reliably maintained in the same release state as before the ON failure of the elements H1 and L2.

  (3) If the potential of the connection node with respect to the motor 2 of each switching element H1, H2, L1, L2 is monitored and the potential is fixed at the same potential as that during ON control at a timing different from the original control timing. It is determined that there is an ON failure. Accordingly, it is possible to accurately determine the ON failure of the switching elements H1, H2, L1, and L2.

  (4) When an ON failure of any of the switching elements H1, H2, L1, and L2 is detected in the parking state before the vehicle travels, driving of the motor 2 by the H-type bridge circuit 3 is prohibited. As a result, the steering lock can be maintained in the locked state. Therefore, in this case, it is possible to prevent the vehicle from traveling while the switching elements H1, H2, L1, and L2 are in the ON failure state.

  (5) When the H-type bridge circuit 3 is short-circuited, the fuse F element is blown, so that power supply to the motor 2 is reliably cut off without being controlled by the microcomputer 10. Therefore, the motor 2 is reliably maintained in the locked state, and thereby the state transition of the steering lock can be reliably prevented.

The first embodiment can be modified and embodied as follows.
-For example, a configuration in which a switching element such as an FET is connected in series downstream of the fuse F and the steering lock is locked when the switching element and the switching elements H1 and L2 are all controlled to be ON can be adopted. Good. In this case, the steering lock is released when the switching elements and the switching elements H2 and L1 are all turned on. Here, when the microcomputer 10 detects the presence or absence of an ON failure of the switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3, the switching element is ON-controlled and determined in the manner shown in FIG. Is made.

  ・ Instead of the fuse F, a switching element such as an FET is provided in the power supply line for the motor 2, and the switching is performed when an ON failure of the switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3 is detected. The power supply to the motor 2 may be cut off by controlling the element OFF. In this case, when the microcomputer 10 detects the presence or absence of an ON failure of the switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3, the mode shown in FIG. The decision is made.

  The switching elements H1, H2, L1, and L2 constituting the H-type bridge circuit 3 are not limited to power MOSFETs. For example, the H-type bridge circuit 3 may be configured by four relays.

-The drive source is not limited to a motor. For example, the lock bar may be displaced using a solenoid as a drive source.
(Second Embodiment)
Next, a second embodiment of the electric steering lock device will be described.

  As shown in FIG. 3, the electric steering lock device according to the second embodiment includes a fuse F and an H-type bridge of the power line of the motor 2 with respect to the steering ECU 1 with respect to the steering ECU 1 of the first embodiment. A short-circuit prevention element HH is provided in series between the circuits 3.

  The short-circuit prevention element HH is composed of a P-channel power MOSFET similar to the switching elements H1 and H2 on the high potential side, the gate is connected to the microcomputer 10, and the source is connected to the + terminal of the + B power supply via the fuse F. Further, the drain is connected to the sources of the elements H1 and H2.

  A monitor terminal a is set to the drain of the short-circuit prevention element HH through a circuit having two resistors. Accordingly, the monitor terminal a of the first embodiment is set as the monitor terminal b, and the monitor terminal b of the first embodiment is set as the monitor terminal c. The microcomputer 10 monitors the potentials of the monitor terminals a to c, analyzes the monitoring results to detect the presence / absence of an ON failure of each element HH, L1, and L2, and further determines each element according to the detection result. ON / OFF control is performed.

Here, a method for determining ON failure will be described.
As shown in FIG. 4, when the short-circuit prevention element HH is determined as an ON failure determination target, the potential of the monitor terminal a is referred to. As shown in the third stage of FIG. 4, when the potential of the monitor terminal a is at the + B level, the ON state of the short-circuit prevention element HH is grasped. In this case, the microcomputer H 10 controls the element HH to be ON. It is determined that there is an ON failure unless That is, if the drain potential of the short-circuit prevention element HH is fixed at the same + B potential as that during ON control at a timing different from the original control timing, it is determined that there is an ON failure of the element HH. As shown in the uppermost stage of FIG. 4, when the potential of the monitor terminal a is at the GND level, it is determined that there is no ON failure of the short-circuit prevention element HH. Incidentally, since the monitor terminal a is disconnected from the 5V system circuit, the detection result that the potential of the monitor terminal a is at the 5V level as shown in the second stage of FIG. It is not used for the failure judgment.

  Even when the switching elements L1 and L2 are determined as ON failure determination targets, the ON failure of each element is determined based on the same principle as described above. When the potential of the monitor terminal b is at the GND level, it is determined that there is an ON failure of the switching element L1, and when the potential of the monitor terminal c is at the GND level, it is determined that there is an ON failure of the switching element L2. When the potential of the monitor terminal b (monitor terminal c) is at 5V level, it is determined that there is no ON failure of the switching element L1 (switching element L2). Incidentally, since the monitor terminal b (monitor terminal c) is disconnected from the + B system circuit, the detection result that the potential of the monitor terminal b (monitor terminal c) is at the + B level is the switching element L1 (switching element L1). It is not used for the failure determination of L2).

Next, the operation of the electric steering lock device will be described.
Prior to starting the engine, when there is a request to release the steering lock, the steering lock is released on the condition that each element HH, L1, L2 has no ON failure. In this case, each element HH, H2, L1 is ON-controlled. On the other hand, if any of the elements HH, L1, and L2 has an ON failure, the steering lock is not locked or released even if requested.

  When an ON failure occurs in the short-circuit prevention element HH during traveling of the vehicle, the element L1 is controlled to be ON among the elements on the low potential side. In addition, when an ON failure occurs in the switching element L2 while the vehicle is running, the other switching element L1 on the same potential side is turned ON to prevent a short circuit of the H-type bridge circuit 3 due to a double failure. The steering lock is prevented from shifting to the locked state due to a triple failure.

As described above, according to the present embodiment, the following effects can be obtained.
(6) When an ON failure of the switching element L2 constituting the H-type bridge circuit 3 is detected during traveling of the vehicle, the switching element L1 on the same potential side as the element L2 is controlled to be ON, thereby locking the motor 2 The steering lock state can be reliably maintained in the same state as before the failure, and a double failure with the switching element H1 or H2 constituting the H-type bridge circuit 3 by providing the short-circuit prevention element HH. It is possible to prevent the H-type bridge circuit 3 from being short-circuited. Therefore, it is possible to cope with a failure of the switching element constituting the H-type bridge circuit 3.

  (7) When an ON failure of the short-circuit prevention element HH is detected during traveling of the vehicle, the H-type bridge circuit 3 is configured by ON-controlling the element L1 among the low-potential side elements of the H-type bridge circuit 3. The motor 2 is locked when a triple failure occurs between the switching element H1 and the element L2, and the steering lock state can be reliably maintained in the same release state as before the failure.

  (8) When an ON failure of any of the switching elements HH, L1, and L2 is detected in the parking state before the vehicle travels, driving of the motor 2 by the H-type bridge circuit 3 is prohibited. As a result, the steering lock can be maintained in the locked state. Therefore, in this case, it is possible to prevent the vehicle from traveling while the switching elements HH, L1, and L2 are in the ON failure state.

(Third embodiment)
Next, a third embodiment of the electric steering lock device will be described.
As shown in FIG. 5, the electric steering lock device according to the third embodiment has a short-circuit prevention element on the upstream side of the H-type bridge circuit 3 with respect to the steering ECU 1 with respect to the steering ECU 1 of the second embodiment. HH is omitted, and a short-circuit prevention element LL is provided on the downstream side of the H-type bridge circuit 3.

  The short-circuit prevention element LL is composed of an N-channel power MOSFET similar to the low-potential side switching elements L1 and L2, and has a gate connected to the microcomputer 10 and a drain connected to each source of the elements L1 and L2. The source is grounded.

  A monitor terminal a is set to the first end of the motor 2, that is, the drain of the switching element H 1 via a circuit with two resistors, and the second end of the motor 2, that is, the drain of the switching element H 2 Similarly, the monitor terminal b is set. A monitor terminal c is set to the drain of the short-circuit prevention element LL through a 5V system circuit. The microcomputer 10 monitors the potential of each of the monitor terminals a to c, analyzes the monitoring result to detect the presence / absence of an ON failure in each of the elements H1, H2, and LL, and further detects each element according to the detection result. ON / OFF control is performed.

Here, a method for determining ON failure will be described.
As shown in FIG. 6, when the short-circuit prevention element LL is determined as an ON failure determination target, the potential of the monitor terminal c is referred to. 6, when the potential of the monitor terminal c is at the GND level, the ON state of the short-circuit prevention element LL is grasped. In this case, the microcomputer 10 controls the element LL to be ON. It is determined that there is an ON failure except in the case where it is set. That is, if the drain potential of the short-circuit prevention element LL is fixed at the same GND potential as that during ON control at a timing different from the original control timing, it is determined that there is an ON failure of the element LL. As shown in the second stage from the bottom in FIG. 6, when the potential of the monitor terminal c is at the 5V level, it is determined that there is no ON failure of the short-circuit prevention element LL. Incidentally, since the monitor terminal c is disconnected from the + B system circuit, the detection result that the potential of the monitor terminal c is at the + B level as shown in the lowest stage of FIG. It is not used for judgment.

  When the switching elements H1 and H2 are determined as ON failure determination targets, the ON failure of each element is determined based on the same principle as described above. When the potential of the monitor terminal a is at the + B level, it is determined that there is an ON failure of the switching element H1, and when the potential of the monitor terminal b is at the + B level, it is determined that there is an ON failure of the switching element H2. When the potential of the monitor terminal a (monitor terminal b) is at the GND level, it is determined that there is no ON failure of the switching element H1 (switching element H2). Incidentally, since the monitor terminal a (monitor terminal b) is disconnected from the 5V circuit, the detection result that the potential of the monitor terminal a (monitor terminal b) is at the 5V level is the switching element H1 (switching element H1). It is not used for the failure determination of H2).

Next, the operation of the electric steering lock device will be described.
Prior to starting the engine, when there is a request for releasing the steering lock, the steering lock is released on condition that there is no ON failure in each of the elements H1, H2, and LL. In this case, each element H2, L1, LL is ON-controlled. On the other hand, if any of the elements H1, H2, and LL has an ON failure, the steering lock is not locked or released even if requested.

  When an ON failure occurs in the short-circuit prevention element LL during traveling of the vehicle, the element H2 is controlled to be ON among the elements on the high potential side. In addition, when an ON failure occurs in the switching element H1 while the vehicle is running, the other switching element H2 on the same potential side is controlled to be ON, thereby preventing a short circuit of the H-type bridge circuit 3 due to a double failure. The steering lock is prevented from shifting to the locked state due to a triple failure.

As described above, according to the present embodiment, the following effects can be obtained.
(9) When an ON failure of the switching element H1 constituting the H-type bridge circuit 3 is detected during traveling of the vehicle, the switching element H2 on the same potential side as the element H1 is ON-controlled, so that the motor 2 is locked. The steering lock state can be reliably maintained in the same state as before the failure, and a double failure with the switching element L1 or L2 constituting the H-type bridge circuit 3 by providing the short-circuit prevention element LL. It is possible to prevent the H-type bridge circuit 3 from being short-circuited. Therefore, it is possible to cope with a failure of the switching element constituting the H-type bridge circuit 3.

  (10) When an ON failure of the short-circuit prevention element LL is detected during traveling of the vehicle, the H-type bridge circuit 3 is configured by ON-controlling the element H2 among the high-potential side elements of the H-type bridge circuit 3. The motor 2 is locked when a triple failure occurs between the switching element H1 and the element L2, and the steering lock state can be reliably maintained in the same release state as before the failure.

  (11) When an ON failure of any of the switching elements H1, H2, and LL is detected in the parking state before the vehicle travels, driving of the motor 2 by the H-type bridge circuit 3 is prohibited. As a result, the steering lock can be maintained in the locked state. Therefore, in this case, it is possible to prevent the vehicle from traveling while the switching elements H1, H2, and LL are in the ON failure.

  DESCRIPTION OF SYMBOLS 1 ... Steering lock electronic control apparatus, 2 ... Motor (drive source), 3 ... H type bridge circuit, 10 ... Microcomputer (failure detection means, switching control means), a ... Monitor terminal, b ... Monitor terminal, c ... Monitor terminal , F ... fuse (power supply cutoff means), H1 ... switching element, H2 ... switching element, HH ... short circuit prevention element, L1 ... switching element, L2 ... switching element, LL ... short circuit prevention element.

Claims (8)

In the electric steering lock device that drives and drives the drive source by the H-type bridge circuit to lock and release the steering lock.
Failure detection means for detecting the presence or absence of an ON failure of the four switching elements constituting the H-type bridge circuit;
An electric steering lock device comprising: a switching control means for controlling ON of a switching element on the same potential side as a switching element in which an ON failure is detected by the failure detecting means. In the electric steering lock device according to claim 1,
The electric power steering lock device, wherein the power supply line for the drive source is provided with a power supply cutoff means for cutting off the supply of power to the drive source when the H-type bridge circuit is short-circuited. When the failure detection means uses two switching elements on the high potential side among the four switching elements constituting the H-type bridge circuit as detection targets for the presence or absence of an ON failure, a connection node of the switching element to the drive source On the condition that the potential of the switching element is fixed at the high potential, two of the four switching elements constituting the H-type bridge circuit on the low potential side are determined to have an ON failure. When a switching element is to be detected for the presence or absence of an ON failure, if there is an ON failure of the switching element, provided that the potential of the connection node of the switching element with respect to the drive source is fixed at the low potential. The electric steering lock device according to claim 1 or 2. The said switching control means prohibits the drive of the said drive source by the said H-type bridge circuit, when the ON failure of any switching element is detected by the said failure detection means. The electric steering lock device described. The electric steering lock device according to any one of claims 2 to 4, wherein the power supply cutoff unit is a fuse in which an element is blown by a short-circuit current associated with a short circuit of the H-type bridge circuit. In the electric steering lock device that drives and drives the drive source by the H-type bridge circuit to lock and release the steering lock.
On the upstream side or downstream side of the H-type bridge circuit, a short-circuit prevention element that is a switching element that prevents a short-circuit of the H-type bridge circuit is provided,
A failure detection means for detecting the presence or absence of an ON failure in the switching element and the short-circuit prevention element constituting the H-type bridge circuit;
Switching control means for controlling ON of the switching element on the same potential side as the switching element in which the ON failure is detected when the failure detecting means detects the ON failure of the switching element constituting the H-type bridge circuit. An electric steering lock device. The switching control means turns on the switching elements constituting the H-type bridge circuit on the side that drives the drive source and releases the steering lock when the failure detection means detects an ON failure of the short-circuit prevention element. The electric steering lock device according to claim 6. The switching control means prohibits driving of the drive source by the H-type bridge circuit when an ON failure of any switching element or the short-circuit prevention element is detected by the failure detection means. The electric steering lock device described.