JP5071313B2 - Indicators for vehicles - Google Patents

Description

  The present invention relates to an indicating instrument for a vehicle.

  2. Description of the Related Art Conventionally, there is known a vehicular indicating instrument that is driven to rotate by a step motor with respect to a pointer that indicates a vehicle state value set based on a zero value according to a rotational position. As a kind of such a vehicle indicating instrument, Patent Document 1 discloses a technique that realizes rotational driving of a pointer by applying an AC driving signal corresponding to an electrical angle to a field winding of a step motor. .

In the vehicle indicating instrument of Patent Document 1, the pointer that returns to the zero position that indicates the zero value of the vehicle state value by rotating in the return zero direction is indirectly stopped by the stopper mechanism at the zero position. Here, an induced voltage is generated in the field winding of the step motor while the pointer is rotating in the return-to-zero direction. On the other hand, when the pointer is stopped, the induced voltage generated in the field winding is reduced. Therefore, when the induced voltage generated in the field winding is detected and the detection result is lower than the set voltage, the step motor reaches the zero point of the electrical angle corresponding to the zero position of the pointer, and the pointer is stopped by the stopper. It is determined that the operation has been stopped by the means, and the zero point is updated. According to this, even if the pointer deviates from the zero position in the opposite direction to the zero return direction due to disturbance such as mechanical vibration before the start of power supply to the step motor, the drive signal control is performed based on the updated accurate zero point. Is possible.
JP 2002-267501 A

  By the way, in the indication instrument for vehicles of patent document 1, after rotating the pointer once in the direction opposite to the zero return direction and swinging it up, the pointer is rotated in the zero return direction and stopped by the stopper means. This is because, when the rotation range of the pointer until it stops is narrow, the rotation speed of the stepping motor that drives the pointer does not increase, and the induced voltage generated in the field winding does not exceed the set voltage. This is to avoid the zero point of being updated erroneously. However, in order to increase the zero point update accuracy, if the swinging amount of the pointer is sufficiently increased to widen the rotation range, the time required to update the zero point becomes longer, which may cause the vehicle occupant to misunderstand that it is malfunctioning. And there was a risk of lowering reliability.

  This invention is made | formed in view of such a problem, The objective is to provide the indication instrument for vehicles with high reliability.

  According to the first aspect of the present invention, the vehicle state value set with reference to the zero value is indicated according to the rotational position, the pointer returning to the zero position indicating the zero value by rotation in the return zero direction, A step motor that has a magnetic winding and that rotates the pointer by applying an AC drive signal corresponding to the electrical angle to the field winding, and a pointer that rotates in the zero return direction stops at the zero position. Corresponding to the zero position of the pointer when an update condition is established that the detection result of the induced voltage by the detecting means is equal to or lower than the set voltage. Update means for updating the zero point of the electrical angle, and control means for controlling the drive signal applied to the field winding based on the zero point updated by the update means, the drive for rotationally driving the pointer in the return zero direction About the zero return drive signal And a control means for continuing the control of the zero return drive signal until the electrical angle at which the update condition is properly established after controlling the needle motor to stop by the stopper means and forcibly stepping out the step motor. And

  According to the above invention, of the drive signals applied to the field winding of the step motor, the zero return drive signal for rotationally driving the pointer in the return zero direction is first set at the zero position of the zero value indication. Is controlled so that the stepping motor is forcibly stepped out by the stopper means. Therefore, if there is no deviation of the pointer from the zero position before the control of the zero return drive signal is started, the pointer is stopped by the stopper means and the step motor is forcibly stepped out. This forced step-out causes the pointer to rotate in the direction opposite to the zero return direction from the zero position corresponding to the zero point, and apparently corresponds to an electrical angle that is 360 degrees out of phase with respect to the electrical angle before the step-out. The position to be reached is reached. Therefore, after the forced step-out, the control of the null drive signal is continued until the electrical angle that is properly established for the update condition in which the detection result of the induced voltage generated in the field winding of the step motor is below the set voltage. Thus, the zero corresponding to the zero position where the induced voltage is reduced by the stop of the pointer can be accurately updated. According to such an invention, since the accuracy of the zero point update can be improved without expanding the rotation range of the pointer accompanying the zero point update, it is possible to shorten the time required for the zero point update and improve the reliability.

  According to the second aspect of the present invention, when the update condition is not satisfied at the electrical angle at which the update condition is normally satisfied, the control means returns until the detection result of the induced voltage by the detection means becomes equal to or lower than the set voltage. Extend control of drive signals. Here, when the deviation of the pointer from the zero position is large before the control of the zero return drive signal is started, the step motor is not forcedly stepped out, and the zero return to the electrical angle at which the update condition is normally established is obtained. Even if the drive signal is controlled, a situation may occur in which the induced voltage generated in the field winding does not fall below the set voltage. Therefore, when the update condition is not satisfied at the electrical angle where the update condition is normally established, the control of the zero return drive signal is extended until the detection result of the induced voltage becomes equal to or lower than the set voltage, thereby Even when the pointer deviation before the start of the control is large, the update condition can be established reliably and the zero point can be updated accurately.

  According to the third aspect of the present invention, the control means drives and rotates the pointer in a direction opposite to the zero return direction from the zero position prior to stopping the pointer by controlling the drive signal. According to this, because the step-out of the stepping motor does not occur, the induced voltage generated in the field winding is set even if the null drive signal is controlled to the electrical angle where the update condition is normally established. When the voltage does not fall below the voltage, the rotation range of the pointer up to the electrical angle can be secured. Therefore, in this case, the zero point can be accurately updated by extending the control of the zero return drive signal without satisfying the update condition at the electrical angle where the update condition is normally established. Moreover, as for the rotation range of the pointer that needs to be secured, the minimum necessary range is required so that the update condition is not satisfied at the electrical angle where the update condition is normally established. It is also possible to improve the appearance by reducing the size.

  According to the fourth aspect of the present invention, the braking and controlling means controls the feedback drive signal so as to straddle the electrical angle that is 180 degrees out of phase with respect to the zero point from the zero point side, and then until the electrical angle that satisfies the update condition. Continue to control the null drive signal. Here, the forced step-out of the step motor is caused by changing the electrical angle to a point 180 degrees out of phase with respect to the zero point corresponding to the zero position while stopping the pointer at the zero position by the stopper means. . Therefore, when the zero return drive signal is controlled so as to straddle the electrical angle that is 180 degrees out of phase with respect to the zero point from the zero point side, the 180 degree phase is obtained in a state where the pointer is stopped at the zero position by the stopper means. The stepping motor can be forcedly stepped out to update the zero point by reliably changing to the electrical angle of deviation.

  According to the fifth aspect of the present invention, the control means continues the control of the zero return drive signal up to the electrical angle that is 360 degrees out of phase with respect to the zero point after the forced step-out of the step motor. Here, the pointer in which the electrical angle corresponding to the rotational position is apparently shifted by 360 degrees due to the forced step-out is the point where the electrical angle is shifted 360 degrees from the zero point by the control of the null drive signal after the forced step-out. Changes to zero position. Therefore, at this time, the pointer is stopped by the stopper means at the zero position, so that the induced voltage generated in the field winding becomes equal to or lower than the set voltage. Therefore, after the step-out of the stepping motor, if the control of the zero return drive signal is continued until the electrical angle is shifted by 360 degrees with respect to the zero point, the update condition is such that the detection result of the induced voltage is not more than the set voltage. Thus, the zero can be accurately updated.

  According to the sixth aspect of the present invention, the control means continues the control of the zero return drive signal up to the electrical angle before reaching the point 360 degrees out of phase with respect to the zero point after the stepping motor is forcibly stepped out. Here, after the stepping motor stepping out, the rotational speed of the stepping motor that drives the pointer increases even before the electrical angle reaches a point that is 360 degrees out of phase with respect to the zero point by controlling the zero return drive signal. By not doing so, the induced voltage generated in the field winding becomes lower than the set voltage. Therefore, if the control of the zero return drive signal is continued until the electric angle before reaching the point 360 degrees out of phase with respect to the zero point after the stepping motor stepping out, the detection result of the induced voltage is set. The update condition that is lower than the voltage is established before the arrival, and the time required for the zero update can be shortened. Moreover, even if the pointer rotates to a position that apparently corresponds to an electrical angle whose phase is shifted by 360 degrees or more with respect to the electrical angle before the step-out due to the forced step-out of the step motor, the pointer until the update condition is satisfied By narrowing the rotation range, unintentional step-out of the step motor can be avoided.

  According to the seventh aspect of the present invention, the detecting means detects the induced voltage generated in the field winding at a detection point as an electrical angle at which the voltage of the drive signal applied to the field winding becomes zero. Then, the control means continues to control the zero return drive signal up to the detection point before reaching the point 360 degrees out of phase with respect to the zero point after the stepping motor stepping out. As a result, at the detection point, the voltage of the drive signal applied to the field winding becomes zero, so that highly accurate detection of the induced voltage generated in the field winding can be easily realized. Therefore, after the step-out of the stepping motor, the control of the zero return drive signal is continued until the detection point before reaching the point 360 degrees out of phase with respect to the zero point. It can be updated accurately.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows a vehicle indicating instrument 1 according to a first embodiment of the present invention. The vehicle indicating instrument 1 is installed as a vehicle speed meter in front of the driver's seat in the vehicle.

  As shown in FIGS. 1 to 3, the vehicle indicating instrument 1 includes an instrument panel 10, a pointer 20, a rotary inner unit 30, a substrate 40, and a control unit 50.

  The instrument panel 10 shown in FIGS. 1 and 2 is disposed with its display surface 10a facing the driver's seat, and has a vehicle speed display unit 11 that displays a vehicle speed value as a vehicle state value. The vehicle speed display unit 11 displays a plurality of vehicle speed values in an arc shape from a zero value (0 km / h) set as a reference to an upper limit value (180 km / h).

  The pointer 20 is connected to the pointer shaft 30b of the turning inner unit 30 on the base end portion 21 side, and is rotatable along the display surface 10a of the instrument panel 10. As a result, the pointer 20 indicating a value corresponding to the rotational position among the vehicle speed values displayed on the vehicle speed display unit 11 is returned to the zero position indicating the zero value by rotating in the return zero direction X (see FIG. 1). It is possible.

  The rotating inner unit 30 includes an inner unit main body 30a, a pointer shaft 30b, and a casing 30c. The internal unit main body 30 a is disposed on the back side of the substrate 40 substantially parallel to the instrument panel 10. The internal unit main body 30a includes a two-phase step motor M, a reduction gear train G, and a stopper mechanism S shown in FIG. 4 in a casing 30c. The pointer shaft 30 b is supported by a casing 30 c fixed to the back surface of the substrate 40, and supports the proximal end portion 21 of the pointer 20 through the substrate 40 and the instrument panel 10. Therefore, the internal unit main body 30a can rotationally drive the pointer shaft 30b coaxially with the output stage gear 34 of the reduction gear train G and thus the pointer 20 by the reduction rotation of the reduction gear train G accompanying the rotation of the step motor M. It has become.

  As shown in FIGS. 4 and 5, the step motor M is a combination of a stator Ms and a magnet rotor Mr. The stator Ms has a yoke 31 and two-phase field windings 32 and 33. The yoke 31 forms a pair of magnetic poles 31a and 31b having a pole shape, and an A-phase field winding 32 is wound around the magnetic pole 31a, while a B-phase field winding is wound around the magnetic pole 31b. 33 is wound. The magnet rotor Mr is coaxially fixed to the rotation shaft 35a of the reduction gear train G. N and S poles as magnetic poles are alternately formed in the circumferential direction on the outer peripheral surface of the magnet rotor Mr that opens a gap between the tip surfaces of the magnetic poles 31 a and 31 b of the yoke 31.

  In the step motor M having such a configuration, an AC phase A drive signal in which the voltage alternates in a cosine function with respect to the electrical angle is applied to the A phase field winding 32 as shown in FIG. On the other hand, an AC B-phase drive signal whose voltage alternates in a sine function with respect to the electrical angle is applied to the B-phase field winding 33 as shown in FIG. Thus, the drive signals of the phases A and B, which are 90 degrees out of phase with each other, are applied to the field windings 32 and 33, so that the alternating magnetic flux generated in the windings 32 and 33 is converted into the yoke 31 and the magnet rotor. It passes between the magnetic poles of Mr. Therefore, the rotational position of the magnet rotor Mr changes in accordance with the voltage change of the drive signals of the A and B phases according to the electrical angle.

  As shown in FIG. 4, the reduction gear train G includes an output gear 34, an input gear 35, and intermediate gears 36 and 37. The output gear 34 is coaxially connected to the pointer shaft 30b. The input stage gear 35 is coaxially supported by a rotating shaft 35a fixed to the casing 30c. The intermediate gears 36 and 37 are coaxially supported by a rotating shaft 36a fixed to the casing 30c, so that they can rotate integrally. The intermediate gear 36 meshes with the output stage gear 34, while the intermediate gear 37 meshes with the input stage gear 35.

  With such a configuration, the reduction gear train G decelerates the rotation of the magnet rotor Mr of the step motor M connected to the input stage gear 35 via the rotary shaft 35a, and is connected to the output stage gear 34 via the pointer shaft 30b. The reduced rotation is transmitted to the indicated pointer 20. Therefore, when the rotational position of the magnet rotor Mr changes according to the change of the drive signals of the A and B phases according to the electrical angle, the rotational position of the pointer 20 also changes. Particularly in this embodiment, the zero position of the pointer 20 shown in FIG. 1 is adjusted in advance so as to accurately correspond to the zero point θ0 (0 degree) of the electrical angle shown in FIG.

  As shown in FIG. 4, the stopper mechanism S includes a contact member 38 and a stopper member 39. The abutting member 38 is formed in a strip plate shape protruding from the output stage gear 34, and can rotate integrally with the gear 34. The stopper member 39 is formed in an L shape protruding inward from the casing 30 c, and the protruding end portion 39 a is located on the rotation track of the contact member 38. Thereby, when the abutting member 38 is abutted and locked to the tip end portion 39a of the stopper member 39, the pointer 20 returns to the zero position in FIG. 1, and the rotation of the pointer 20 in the return zero direction X is stopped. It will be. As described above, in the present embodiment, the pointer 20 that is rotated in the return zero direction X and returned to the zero position is indirectly stopped by the stopper mechanism S.

  The control unit 50 shown in FIG. 2 is mainly composed of a microcomputer and is mounted on the substrate 40. The control unit 50 can realize a predetermined operation by executing a computer program stored in the built-in memory 52 shown in FIG. 3 under power supply.

  The control unit 50 is electrically connected to the vehicle door sensor 60, the ignition switch IG, and the battery power source B. The control unit 50 is started by direct power supply from the battery power source B when the door sensor 60 detects the opening of the vehicle door. When the ignition switch IG is turned on before a set time (for example, 2 minutes) elapses, the started control unit 50 maintains the operating state by power supply from the battery power supply B, and then the ignition switch IG is turned off. Operation is stopped. On the other hand, the started control unit 50 is temporarily stopped when the ignition switch IG is not turned on until the set time elapses, and then restarted when the ignition switch IG is turned on. Operation stops when IG is turned off. In addition to restarting the control unit 50 after starting once, it is performed in response to, for example, opening the door of the vehicle, depressing the brake pedal, etc. in addition to performing it in response to turning on the ignition switch IG. May be.

  The control unit 50 is further electrically connected to the field windings 32 and 33 of the step motor M, and feeds power to the field windings 32 and 33 in the operating state. In particular, the control unit 50 of the present embodiment controls the drive signals for both the A and B phases applied to the field windings 32 and 33 of the step motor M as the nulling process, which will be described in detail later. An induced voltage generated in the magnetic windings 32 and 33 is detected.

  Here, at the electrical angle at which the signal voltage is greater than zero (0V) for the drive signals of the A and B phases, the path for applying a signal to the corresponding field windings 32 and 33 is electrically connected by the switching function. In both cases, the path for detecting the induced voltage generated in the corresponding winding is cut off. On the other hand, at the electrical angle where the signal voltage is zero (0V) for the drive signals of the A and B phases, the switching function cuts off the path for applying a signal to the corresponding field windings 32 and 33, and The path for detecting the induced voltage generated is electrically connected to the corresponding winding. Therefore, in this embodiment in which the driving signals of the phases A and B alternate in the form of a cosine function and a sine function according to the electrical angle, the phase shift of 90 degrees from the zero point θ0 indicated by the black circle in FIG. 6 and the zero point θ0. The electrical angle is set to the detection point θd of the induced voltage. That is, in this embodiment, the detection interval Δθd of the induced voltage is set to a phase width of 90 degrees in electrical angle. As for the switching function of the control unit 50, for example, the path may be connected and disconnected by switching processing in the microcomputer constituting the control unit 50, and the input / output port of the microcomputer may be connected. The path may be connected and disconnected by switching.

  The control unit 50 is further electrically connected to a vehicle speed sensor 62 of the vehicle. In the operating state after the nulling process, the control unit 50 controls the driving signals of both phases A and B based on the zero point θ0 of the electrical angle stored in the memory 52, thereby determining the detected vehicle speed value of the vehicle speed sensor 62. The pointer 20 is instructed. Here, as the zero point θ0 stored in the memory 52, as described in detail later, the latest one updated by the nulling process is used.

  Hereinafter, a control flow for carrying out the nulling process of the first embodiment by the control unit 50 will be described in detail with reference to FIG. This control flow is started when the control unit 50 is started, and the deviation from the zero position of the pointer 20 occurring before the start of power feeding to the field windings 32 and 33 due to the start is as follows. Hereinafter, it will be referred to as “guideline deviation before feeding”.

  First, in S1 of the control flow, a drive signal having a voltage corresponding to the zero point θ0 of the electrical angle is applied to the field windings 32 and 33 of the A and B phases as initial drive signals of the A and B phases. In S2, the current electrical angle is set to the reference point θb. As a result, when the phase shift of the electrical angle due to the shift of the pointer before power feeding is smaller than 180 degrees with respect to the zero point θ0, the pointer 20 is rotationally driven to the zero position by the change of the electrical angle to the zero point θ0. θ0 is set as the reference point θb. On the other hand, when the phase shift of the electrical angle due to the shift of the pointer before power feeding is greater than 180 degrees with respect to the zero point θ0, the pointer 20 moves to a position corresponding to one of the electrical angles shifted in phase by 360 degrees from the zero point θ0. It is rotationally driven and one of the electrical angles is set to the reference point θb.

  Next, in S3, synchronous sub-processing is performed. In this synchronous sub-process, a driving signal for synchronizing the electrical angle and the magnetic pole of the magnet rotor Mr by the rotational driving of the pointer 20 in the return zero direction X is used as a synchronous driving signal for the phases A and B. Applied to the field windings 32 and 33 of each phase. Further, in the synchronous sub-process, the electrical angle is set to the reference point θb by the rotational drive of the pointer 20 in the counter-zero direction Y (see FIG. 1) opposite to the return-zero direction X as return drive signals for the phases A and B. Is applied to the field windings 32 and 33 of the phases A and B.

  In the subsequent S4, as the drive signals for the A and B phases, the drive signals for rotating and driving the pointer 20 in the counter-zero direction Y are used as the field windings 32 and 33 for the A and B phases. Apply to. At this time, the swing amount R (see FIGS. 8 to 10) of the pointer 20 is preferably less than 180 degrees in terms of electrical angle, and is set to 90 degrees in the present embodiment.

  In the subsequent S5, the pointer 20 is rotationally driven in the zero return direction X so as to straddle the electrical angle shifted by 180 degrees from the reference point θb from the reference point θb side as a zero return drive signal for each of the phases A and B. Drive signals are applied to the A and B field windings 32 and 33. Here, when the reference point θb is coincident with the zero point θ0 by S1 and S2, the zero return drive signal indicates the critical point θth that is 180 degrees out of phase with the zero point θ0 (see FIGS. 8 to 10). It is controlled so as to straddle from the zero point θ0 side. Therefore, in that case, first, the electrical angle changes to the zero point θ0, the pointer 20 is stopped at the zero position by the stopper mechanism S, and further, under the stopped state, the electric angle is changed to the critical point θth that is 180 degrees out of phase from the zero point θ0. The step-out of the stepping motor M occurs when the angle changes reliably. By such a forced step-out, the pointer 20 rotates to a position that apparently corresponds to an electrical angle that is 360 degrees out of phase with respect to the critical point θth with the zero point θ0 interposed therebetween.

  In S6 after this, the zero return drive signals of the phases A and B are continuously applied to the field windings 32 and 33, and in S7, the electrical angle is applied to the detection point θd that is 360 degrees out of phase with the reference point θb. It is determined whether or not has reached. As a result, if a negative determination is made, the process returns to S6 and repeats S6 and the subsequent S7 to further continue the application control of the null drive signal, while if an affirmative determination is made, The process proceeds to S8.

  In S8, among the A and B phase field windings 32 and 33, the detection target winding in which the voltage of the null drive signal becomes zero at the current detection point θd that is 360 degrees out of phase with the reference point θb (here) Then, the induced voltage of the field winding 33) is detected, and it is determined whether the update condition is met so that the detection result is equal to or lower than the set voltage. As a result, if a positive determination is made, the process proceeds to S9, whereas if a negative determination is made, the process proceeds to S10.

  In S9 when the update condition is satisfied, it is assumed that the pointer 20 has returned to the zero position, and the zero point θ0 is updated by the current detection point θd that is 360 degrees out of phase with the reference point θb, and the update result is stored in the memory 52. To do. On the other hand, in S10 when the update condition is not satisfied, the pointer 20 is not returned to the zero position, and it is assumed that the induced voltage of the detection target winding is in a rotating state exceeding the set voltage. The phase null drive signal is extended and applied to the field windings 32 and 33. In subsequent S11, it is determined whether or not the electrical angle has reached a detection point θd that is 90 degrees out of phase from the detection point θd of the immediately preceding induced voltage. Here, the detection point θd of the immediately preceding induced voltage refers to the electrical angle when the induced voltage is detected by the process closest to the execution time in S8 and S12 described later. If a negative determination is made as a result of such a determination, the process returns to S10 and repeats S10 and the subsequent S11, thereby further extending the application control of the null drive signal while making a positive determination. If so, the process proceeds to S12.

  In S12, among the field windings 32 and 33 of the A and B phases, the induced voltage of the detection target winding in which the voltage of the null drive signal becomes zero at the current detection point θd determined to be reached in the immediately preceding S11 Is detected, and it is determined whether or not an update condition for which the detection result is equal to or lower than the set voltage is satisfied. As a result, when a negative determination is made, the process returns to S10 and repeats S10 and subsequent S11 and S12, thereby further extending the application control of the null drive signal. On the other hand, if an affirmative determination is made, it is determined that the pointer 20 has returned to the zero position, the process proceeds to S13, the zero point θ0 is updated with the current detection point θd, and the update result is stored in the memory 52.

  In S14 after the zero point θ0 is updated and stored in S9 and S13, the correction sub-process is performed. This correction sub-process is stored in the memory 52 when there is a deviation between the rotational position of the pointer 20 stopped at the zero position by the stopper mechanism S and the zero value displayed on the vehicle speed display unit 11. This is performed to correct the deviation based on the characteristic data. At the end of the correction sub-process, the electrical angle is set to the latest zero point θ0, and this control flow ends.

  Hereinafter, an operation example realized by the nulling process of the first embodiment will be described with reference to FIGS. 8 to 10, the alternate long and short dash line graph represents the time change of the electrical angle, and the solid line graph represents the time change of the rotational position of the pointer 20 by the time change of the electrical angle corresponding thereto. It is a thing.

(Operation example I)
FIG. 8 shows a case where the phase shift of the electrical angle due to the shift of the pointer before feeding is 90 degrees smaller than 180 degrees. In this case, when the control unit 50 is started, the electrical angle changes to the zero point θ0 that is the reference point θb, and the pointer 20 is rotationally driven to the zero position (t1). Subsequently, after the synchronous sub-process is performed (t1 to t2), the pointer 20 is swung up by the swing amount R in the counterclockwise zero direction Y from the zero position (t2 to t3).

  Next, by the control of the zero return drive signal as shown in FIG. 11, first, the electrical angle changes to the zero point θ0 as the reference point θb and the pointer 20 is rotationally driven to the zero position in the return zero direction X. The stopper mechanism S stops the pointer 20 at the zero position (t4). Further, under the stop state of the pointer 20 by the stopper mechanism S, the electric angle changes so that the phase from the zero point θ0 to the critical point θth is shifted by 180 degrees by the control of the zero return drive signal as shown in FIG. Is generated (t5), the pointer 20 rotates in the counterclockwise zero direction Y. As a result, the rotational position of the pointer 20 is a position that apparently corresponds to an electrical angle that is 360 degrees out of phase with respect to the zero point θ0 from the critical point θth, that is, a phase that is 180 degrees from the zero point θ0 to the opposite side of the critical point θth. It becomes a position that apparently corresponds to the shifted electrical angle. Incidentally, the pointer 20 of the present embodiment is slightly shifted from the zero position to the zero return direction X as shown in FIG. 8 due to its elastic deformation until the electrical angle changes from the zero point θ0 to the critical point θth. It is like that.

  Thereafter, the electrical angle changes from the zero point θ0 as the reference point θb to the detection point θd that is 360 degrees out of phase by the control of the zero return drive signal as shown in FIG. 11, that is, from the critical point θth at the time of forced step-out to 180 °. The electrical angle changes up to the detection point θd that is out of phase (t6). Thus, at the time of the previous forced step-out, the pointer 20 rotating to the corresponding position of the electrical angle that is 360 degrees out of phase from the critical point θth is driven to rotate to the zero position corresponding to the zero point θ0. A stop action is received from the stopper mechanism S. At this time, in the present embodiment, the induced voltage of the detection target winding among the field windings 32 and 33 of each of the A and B phases is equal to or lower than the set voltage. The detection point θd at the time of establishment that is 360 degrees out of phase from the zero point θ0 is updated as the latest zero point θ0. After this update, the correction sub-process (t6 to t7) is performed. In addition, for example, the zero point θ0 may be performed at the end of the correction sub-process (t7). .

  As described above, in the first embodiment, when the phase shift of the electrical angle due to the deviation of the pointer before power feeding is smaller than 180 degrees, the update condition is made normal by rotating the pointer 20 to the zero position after the stepping-out of the step motor M. Can be correctly updated as the zero point θ0. According to this, the update accuracy of the zero point θ0 can be improved without increasing the amount of swing R of the pointer 20 in the reversal zero direction Y sufficiently to increase the rotation range of the pointer 20 necessary for the zero point update. Can be. Therefore, the time required for updating the zero point θ0 can be shortened to improve the reliability, and the appearance can be improved.

(Operation example II)
FIG. 9 shows a case where the phase shift of the electrical angle due to the shift of the pointer before power feeding is 270 degrees larger than 180 degrees. In this case, when the control unit 50 is started, the electrical angle changes from the zero point θ0 to the reference point θb that is 360 degrees out of phase, and the pointer reaches the position corresponding to the reference point θb in the reversal zero direction Y from the zero position. 20 is driven to rotate (t1). Subsequently, after the synchronization sub-process is performed (t1 to t2), the pointer 20 is swung up from the corresponding position of the reference point θb by the swing amount R in the return zero direction Y, and the electrical angle is changed from the zero point θ0 to ( 360 + R) degrees out of phase (t2 to t3).

  Thereafter, the electrical angle is changed by the control of the null return drive signal, and the pointer 20 is rotationally driven in the null return direction X. However, the electrical angle change amount until the first determination of the update condition is (360 + R) degrees. Therefore, the electrical angle does not reach the critical point θth that causes the stepping motor M to step out. Further, since the electrical angle change amount until the first determination becomes (360 + R) degrees, the pointer 20 is rotationally driven to the zero position and stopped by the stopper mechanism S (t6). At this time, in the present embodiment, the induced voltage of the detection target winding out of the field windings 32 and 33 of the respective phases A and B is equal to or lower than the set voltage. Therefore, the detection point θd when the update condition is satisfied is satisfied. The zero point θ0 is updated as the latest zero point θ0. After this update, correction sub-processing (t6 to t7) is performed.

  As described above, in the first embodiment, the update accuracy of the zero point θ0 can be improved even in a situation in which the step-out of the step motor M does not occur due to the phase shift of the electrical angle due to the shift of the pointer before feeding. is there.

(Operation example III)
FIG. 10 shows a case where the phase shift of the electrical angle due to the deviation of the pointer before feeding is 630 degrees which is larger than 180 degrees. In this case, when the control unit 50 is started, the electrical angle changes from the zero point θ0 to the reference point θb that is 720 degrees out of phase, and the pointer moves to the position corresponding to the reference point θb in the reversal zero direction Y from the zero position. 20 is driven to rotate (t1). Subsequently, after the synchronization sub-process is performed (t1 to t2), the pointer 20 is swung up from the corresponding position of the reference point θb by the swing amount R in the return zero direction Y, and the electrical angle is changed from the zero point θ0 to ( 720 + R) degrees out of phase (t2 to t3).

  Thereafter, the electrical angle is changed by the control of the zero return drive signal and the pointer 20 is rotationally driven in the zero return direction X. However, until the first determination of the update condition, the electrical angle change amount is (360 + R) degrees. Therefore, the electrical angle does not reach the critical point θth that causes the stepping motor M to step out. Further, until the first determination time, the electrical angle change amount is (360 + R) degrees, so that the rotational position of the pointer 20 becomes a position corresponding to the electrical angle that is 360 degrees out of phase from the zero point θ0 (t6). . At this time, in this embodiment, since the rotational speed of the step motor M that drives the pointer 20 is sufficiently increased by appropriately setting the swing amount R of the pointer 20, the field windings for the phases A and B are provided. The induced voltage of the winding to be detected out of 32 and 33 exceeds the set voltage, and the update condition is not satisfied at the first determination.

  Therefore, in the present embodiment, when the update condition is not satisfied at the time of the first determination, the control of the zero return drive signal is extended. As a result, the electrical angle changes and the pointer 20 is rotationally driven in the return zero direction X. However, the electrical angle reaches the zero point θ0 before the critical point θth that causes the stepping motor M to step out. It will be. Further, until the electrical angle reaches the zero point θ0, the rotation speed of the step motor M is sufficiently increased, so that the detection target winding among the field windings 32 and 33 of the A and B phases is induced. The voltage will exceed the set voltage. Therefore, when the pointer 20 that has returned to the zero position when the electrical angle reaches the zero point θ0 is stopped by the stopper mechanism S (t8), the induced voltage of the detection target winding becomes equal to or lower than the set voltage, and the update condition is satisfied. The zero point θ0 that is the detection point θd at the time of establishment is updated as the latest zero point θ0. After this update, correction sub-processing (t6 to t7) is performed.

  As described above, in the first embodiment, even when there is no forced step-out of the step motor M due to the large phase shift of the electrical angle due to the shift of the pointer before power feeding, the zero point θ0 is controlled by the extension control of the zero return drive signal. The update accuracy can be increased.

  In the first embodiment so far, the stopper mechanism S corresponds to the “stopper means”, the control unit 50 that executes the control flows S7, S8, S11, and S12 corresponds to the “detection means”, and the control flow. The control unit 50 that executes S8, S9, S12, and S13 corresponds to “update means”, and the control unit 50 that executes S1 to S14 of the control flow corresponds to “control means”.

(Second embodiment)
As shown in FIG. 12, the second embodiment of the present invention is a modification of the first embodiment. In the control flow of the second embodiment, the specific detection that is the detection point θd immediately before reaching the point 360 degrees out of phase with the reference point θb in the subsequent S207 under the condition that the application of the null drive signal is continued in S6. It is determined whether or not the electrical angle has reached the point θds, that is, the specific detection point θds that is 270 degrees out of phase with the reference point θb. As a result, when a negative determination is made, the process returns to S6 and repeats S6 and subsequent S207 to further continue the application control of the null drive signal, while when an affirmative determination is made, The process proceeds to S208.

  In S208, among the field windings 32 and 33 for the phases A and B, induction of the detection target winding (here, the field winding 32) at which the voltage of the null drive signal becomes zero at the specific detection point θds. A voltage is detected, and it is determined whether an update condition that results in a detection result equal to or lower than a set voltage is satisfied. As a result, when a negative determination is made, the process proceeds to S10, whereas when an affirmative determination is made, the process proceeds to S209.

  In S209, the electrical angle θcal obtained by adding the detection interval Δd to the specific detection point θds, that is, the electrical angle θcal shifted by 360 degrees from the reference point θb is calculated, and the latest zero point θ0 at which the pointer 20 returns to the zero position is calculated. The angle θcal is updated and stored in the memory 52. In the present embodiment, after the execution of S209, the process proceeds to S14 and the correction sub-process is performed, whereby the electrical angle is set to the latest zero point θ0, and the control flow ends.

  Hereinafter, an operation example realized by the nulling process of the second embodiment will be described with reference to FIGS. 13 to 15, the alternate long and short dash line graph represents the time change of the electrical angle, and the solid line graph represents the time change of the rotational position of the pointer 20 by the time change of the electrical angle corresponding thereto. It is a representation.

(Operation example I)
FIG. 13 shows a case where the phase shift of the electrical angle due to the shift of the pointer before power feeding is 90 degrees smaller than 180 degrees. In this case, immediately after the start of the control unit 50 (t1), the rotational position of the pointer 20 that is rotationally driven to the corresponding position of the zero point θ0 that becomes the reference point θb is 360 degrees from the critical point θth across the zero point θ0. The operation is the same as that of the operation example I of the first embodiment until the rotation position that apparently corresponds to the electrical angle whose phase is shifted (t5).

  After that, the electrical angle is returned to the specific detection point θds immediately before the electrical angle shifted 360 degrees from the zero point θ0 as the reference point θb, that is, to the specific detection point θds shifted 270 degrees from the zero point θ0. The pointer 20 is rotationally driven in the return zero direction X by changing the control. As a result, the pointer 20 has a position that apparently corresponds to an electrical angle that is 360 degrees out of phase with respect to the zero point θ0 from the specific detection point θds, that is, a position that apparently corresponds to an electrical angle that is 90 degrees out of phase from the zero point θ0. Driven by rotation (t6). Therefore, although the pointer 20 is not stopped by the stopper mechanism S, the rotational speed of the stepped motor M that has been forcibly stepped out cannot sufficiently increase up to the specific detection point θds. Of the windings 32 and 33, the induced voltage of the detection target winding is equal to or lower than the set voltage. As a result, since the update condition is normally established at the first determination at the specific detection point θds, the electrical angle θcal when the pointer 20 returns to the zero position is based on the specific detection point θds before the return. By calculating, the zero point θ0 can be correctly updated to the electrical angle θcal. After this update, correction sub-processing (t6 to t7) is performed.

  According to such a second embodiment, it is not necessary to sufficiently increase the amount of swing R of the pointer 20 in the reversal zero direction Y so as to expand the rotation range of the pointer 20 necessary for updating the zero point θ0. The update accuracy of the zero point θ0 can be improved. Therefore, the time required for updating the zero point θ0 can be drastically shortened and the reliability can be improved. Moreover, even if the pointer 20 rotates to a position that apparently corresponds to an electrical angle whose phase is shifted by 360 degrees or more from the critical point θth due to the forced step-out of the step motor M, 180 degrees in terms of electrical angle from the rotational position. The update of the zero point θ0 is completed at the specific detection point θd within the phase width. That is, after the forced step-out, the rotation range of the pointer 20 until the update of the zero point θ0 is completed is smaller than a phase width of 180 degrees at which an unintended step-out occurs in the step motor M in terms of the electrical angle. Unintentional step-out can be avoided.

(Operation example II)
FIG. 14 shows a case where the phase shift of the electrical angle due to the deviation of the pointer before feeding is 270 degrees larger than 180 degrees. In this case, immediately after the control unit 50 is started (t1), the rotational position of the pointer 20 that is rotationally driven to the corresponding position of the reference point θb that is 360 degrees out of phase from the zero point θ0 is swung up from the zero point θ0 to (360 + R) degrees. The operation is the same as that of the operation example II of the first embodiment until the position corresponding to the electrical angle shifted in phase is reached (t3).

  After that, the electrical angle is changed by the control of the null return drive signal, and the pointer 20 is rotationally driven in the null return direction X. The change amount of the electrical angle until the first determination of the update condition is (270 + R) degrees. It becomes. Therefore, by the time of the first determination, the stepping motor M is not forcedly stepped out due to the electrical angle reaching the critical point θth, and at the time of the determination, the rotational position of the pointer 20 is 90 degrees out of phase from the zero point θ0. Corresponding to the specific detection point θds (t6). At this time, in the second embodiment in which the swing amount R of the pointer 20 is 90 degrees larger than that of the first embodiment, the rotational speed of the step motor M that drives the pointer 20 can be sufficiently increased. . Therefore, since the induced voltage of the detection target winding out of the field windings 32 and 33 of each phase A and B exceeds the set voltage, the update condition is not satisfied at the first determination.

  Therefore, in the second embodiment, when the update condition is not satisfied at the time of the first determination, the control of the zero return drive signal is extended. As a result, the electrical angle changes and the pointer 20 is rotationally driven in the return zero direction X. However, until the electrical angle reaches the zero point θ0 and the pointer 20 returns to the zero position, the forced step-out of the step motor M is not performed. It does not occur, and the induced voltage in the detection target winding out of the field windings 32 and 33 of the A and B phases exceeds the set voltage. Therefore, when the pointer 20 that has returned to the zero position by the electrical angle reaching the zero point θ0 is stopped by the stopper mechanism S (t8), the renewal condition is satisfied because the induced voltage of the winding to be detected becomes lower than the set voltage. The zero point θ0 that is the detection point θd at the time of establishment is updated as the latest zero point θ0. After this update, correction sub-processing (t6 to t7) is performed.

  In such a second embodiment, even in a situation where the step-out of the step motor M does not occur due to the phase shift of the electrical angle due to the shift of the pointer before feeding, the zero point θ0 is controlled by the extension control of the zero return drive signal. The update accuracy can be increased.

(Operation example III)
FIG. 15 shows a case where the phase shift of the electrical angle due to the shift of the pointer before feeding is 630 degrees larger than 180 degrees. In this case, the operation is the same as the operation example II of the present embodiment except for the following differences. Here, one of the differences is that immediately after the control unit 50 is started (t1), the pointer 20 is rotationally driven to a corresponding position of the reference point θb that is 720 degrees out of phase from the zero point θ0. Another difference is that the rotational position of the pointer 20 by swinging up becomes a corresponding position of an electrical angle shifted by (720 + R) degrees from the zero point θ0 (t3). Another difference is that the electrical angle change amount until the determination of the first update condition is (270 + R) degrees, so that the rotational position of the pointer 20 at the time of the determination has a phase of 450 degrees from the zero point θ0. The position corresponds to the shifted specific detection point θds (t6).

  Therefore, in such a second embodiment, even when there is no forced step-out of the step motor M due to a large phase shift of the electrical angle due to the shift of the pointer before power feeding, the extension control of the zero return drive signal is performed. The update accuracy of the zero point θ0 can be increased.

  In the second embodiment so far, the control unit 50 that executes S207, S208, S11, and S12 of the control flow corresponds to “detection means”, and the control that executes S208, S209, S12, and S13 of the control flow. The unit 50 corresponds to “update means”, and the control unit 50 that executes S1 to S6, S10 to S14, and S207 to S209 of the control flow corresponds to “control means”.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. it can.

  Specifically, as the “stopper means”, the pointer 20 may be directly locked and stopped. In addition, as for the driving signals of the A and B phases, if the signals alternate according to the electrical angle, the voltage changes to a trapezoidal waveform, a triangular waveform, or the like other than a signal whose voltage changes to a cosine function or a sine function. It may be a signal. Further, the vehicle state value instructed by the pointer 20 may be, for example, the remaining fuel amount, the coolant temperature, the engine speed, or the like as long as it is a value relating to various vehicle states. Further, in the control flow, any one of S3 for executing the synchronization sub-process, S4 for raising the pointer 20 and S14 for executing the correction sub-process may not be executed.

It is a front view which shows the indicator device for vehicles by 1st embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is a block diagram which shows the electric circuit structure of the indicator device for vehicles by 1st embodiment of this invention. It is a perspective view which shows the principal part of the indicator device for vehicles by 1st embodiment of this invention. It is a top view which shows the principal part of the indicator device for vehicles by 1st embodiment of this invention. It is a characteristic view for demonstrating the drive signal of the indicator device for vehicles by 1st embodiment of this invention. It is a flowchart which shows the control flow of the indicator device for vehicles by 1st embodiment of this invention. FIG. 6 is a characteristic diagram for explaining an operation example I of the vehicle indicating instrument according to the first embodiment of the present invention. It is a characteristic view for demonstrating the operation example II of the indicator device for vehicles by 1st embodiment of this invention. It is a characteristic view for demonstrating the operation example III of the indicator device for vehicles by 1st embodiment of this invention. It is a characteristic view for demonstrating the zero return drive signal of the indicator device for vehicles by 1st embodiment of this invention. It is a flowchart which shows the control flow of the indicator device for vehicles by 2nd embodiment of this invention. It is a characteristic view for demonstrating the operation example I of the indicator device for vehicles by 2nd embodiment of this invention. It is a characteristic view for demonstrating the operation example II of the indicator device for vehicles by 2nd embodiment of this invention. It is a characteristic view for demonstrating the operation example III of the indicator device for vehicles by 2nd embodiment of this invention.

Explanation of symbols

1 vehicle indicating instrument, 10 instrument panel, 10a display surface, 11 vehicle speed display section, 20 pointer, 30 rotating inner machine, 30a inner machine body, 31 yoke, 32, 33 field winding, 38 abutting member, 39 Stopper member, 40 substrate, 50 control unit (detection means / update means / control means), 52 memory, B battery power supply, G reduction gear train, M step motor, Mr magnet rotor, Ms stator, S stopper mechanism (stopper means) , Θ0 zero

Claims (7)

Indicating a vehicle state value set based on the zero value according to the rotational position, and a pointer that returns to the zero position indicating the zero value by rotation in the return zero direction;
A step motor that has a field winding and rotationally drives the pointer by applying an AC drive signal according to an electrical angle to the field winding;
Stopper means for stopping the pointer rotating in the return zero direction at the zero position;
Detecting means for detecting an induced voltage generated in the field winding;
An update means for updating a zero point of the electrical angle corresponding to the zero position when an update condition is established in which a detection result by the detection means is a set voltage or less;
Control means for controlling the drive signal applied to the field winding based on the zero point updated by the update means, the return signal being the drive signal for rotationally driving the pointer in the return zero direction. With respect to the zero drive signal, the pointer is stopped by the stopper means and the step motor is forced to step out, and then the control of the null drive signal is continued until the electrical angle at which the update condition is properly established. Control means to
A vehicle indicating instrument comprising:   The control means extends the control of the zero return drive signal until the detection result by the detection means becomes a set voltage or lower when the update condition is not satisfied at the electrical angle at which the update condition is normally satisfied. The vehicle indicating instrument according to claim 1.   3. The control means according to claim 2, wherein the control means drives and rotates the pointer in a direction opposite to the zero return direction from the zero position before the stop of the pointer by the control of the driving signal. The vehicle indicating instrument as described.   The control means controls the feedback drive signal so as to straddle the electrical angle that is 180 degrees out of phase with respect to the zero point from the zero point side, and then returns the return to the electrical angle at which the update condition is properly established. The vehicle indicating instrument according to any one of claims 1 to 3, wherein the control of the zero drive signal is continued.   The said control means continues control of the said zero return drive signal to the said electrical angle which carried out 360 degree phase shift | offset | difference with respect to the said zero point after forced step-out of the said step motor. The vehicle indicating instrument according to claim 1.   The control means continues the control of the zero return drive signal up to the electrical angle before reaching a point 360 degrees out of phase with respect to the zero point after the stepping motor is forcibly stepped out. Item 5. The vehicle indicating instrument according to any one of Items 1 to 4. The detection means detects the induced voltage generated in the field winding at a detection point as the electrical angle at which the voltage of the drive signal applied to the field winding becomes zero,
The control means continues the control of the return-to-zero drive signal until the detection point before reaching a point that is 360 degrees out of phase with respect to the zero point after the step-out of the step motor is forced. Item 7. The vehicle indicating instrument according to Item 6.