JP4952412B2 - Rotational speed detection backup device - Google Patents

Description

  The present invention includes a main rotation speed sensor and a sub rotation speed sensor, and selects a higher rotation speed from among the rotation speeds obtained from the detection of these rotation speed sensors. The present invention relates to a rotational speed detection backup device that performs backup at the same time.

  A rotational speed sensor that detects the rotational speed and crank angle of an output shaft is used for control of a rotational driving force source, for example, control of an internal combustion engine for a vehicle or motor control. If this rotational speed sensor fails, the rotational driving force source cannot be operated normally.

  However, even if this rotational speed sensor (main rotational speed sensor) breaks down, the rotational driving force source is not immediately stopped, but another rotational speed sensor (sub-motor) is provided so that at least retreating to a repair shop is possible. In some cases, a rotation speed sensor) is provided to perform abnormality determination or backup (see, for example, Patent Document 1). Such abnormality determination and backup of the rotational speed sensor are the same when detecting the rotational speed of other rotational shafts, for example, when detecting the rotational speed of the input / output shaft in the transmission mechanism of the vehicle and using it for shift control. is there.

In Patent Document 1, when the rotation speed sensor fails due to disconnection or the like, the detection value of the rotation speed sensor rapidly decreases to almost 0 rpm, so that the detection values of the main rotation speed sensor and the sub rotation speed sensor are used as backup processing. The larger one is used as judged normal.
JP-A-8-70504 (page 3, FIG. 3)

  The sub rotational speed sensor described above may be newly provided, but is already provided in another mechanism interlocked with the output shaft of the rotational driving force source and detects the rotational speed of the shaft in this mechanism. May be diverted. The sub rotational speed sensor provided in this way does not always have the same responsiveness as the main rotational speed sensor. Therefore, always using the output of the main rotational speed sensor at normal time is important for stable rotational driving force source control.

  For this reason, it is conceivable to provide a reduction offset in the rotation speed detected by the sub rotation speed sensor. If there is no large difference in responsiveness between the sub rotation speed sensor and the main rotation speed sensor, the main rotation speed is always used in normal operation by providing a difference between both rotation speeds with a small reduction offset. It will be. Only when the main rotational speed sensor fails, it is possible to back up with the detection value of the sub rotational speed sensor. For this reason, stable rotational driving force source control is possible under normal conditions, and even when the main rotational speed sensor fails, there is no need for a large step in the rotational speed used for control, and relatively stable rotational driving force source control continues. it can.

  However, if the difference in responsiveness between the main rotational speed sensor and the sub rotational speed sensor is greatly different, even if both rotational speed sensors are normal when the rotational speed changes, the detected value will have a large difference. Become. For example, if the detection value of the sub rotation speed sensor temporarily becomes larger than the detection value of the main rotation speed sensor due to a difference in response, if this difference exceeds the decrease offset, the sub rotation speed is used for control even under normal conditions. A state occurs. When the rotation speed change stops, the main rotation speed is again used for control. As described above, since the rotation speed is repeatedly switched in the normal state, the stability of the rotational driving force source control may be impaired.

  In order to prevent this, it is conceivable to increase the reduction offset so as to cover all the changes in the rotational speed from the beginning. However, in this case, when the main rotational speed sensor fails, a large drop in the rotational speed is generated at the timing when the main rotational speed sensor is switched to the secondary rotational speed, and the rotational driving force source control may become unstable.

  The present invention provides a rotational speed detection backup device that includes a main rotational speed sensor and a sub rotational speed sensor, and that does not easily cause instability of control even when the rotational driving force source control is performed using the rotational speed on the higher side. It is the purpose.

In the following, means for achieving the above object and its effects are described.
The rotational speed detection backup device according to claim 1 is provided for a main rotational speed sensor provided for a measurement target rotation axis, and for the measurement target rotation axis or an axis linked to the measurement target rotation axis. A sub-rotation speed sensor, and a main rotation speed of the measurement target rotation shaft obtained by detection of the main rotation speed sensor and a sub rotation speed of the measurement target rotation shaft obtained by detection of the sub rotation speed sensor. Rotation speed detection backup device that performs backup in the event of failure of any rotation speed sensor by selecting the higher rotation speed at the measurement object rotation obtained from the detection value of the sub rotation speed sensor A sub rotation speed sensor reduction offset means for adding a reduction offset to the shaft sub rotation speed, and the main rotation speed and the sub rotation speed sensor reduction offset means. A rotation state detecting means for detecting a rotation state of the rotating shaft to be measured, which changes a difference between the sub rotation speed before the decrease offset or the sub rotation speed after the decrease offset, and the rotation state detection means performs the rotation. An offset adjusting means for changing the decreasing offset in a direction to absorb the change in the difference when the state is detected is provided.

  As described above, when the rotation state of the measurement target rotating shaft in which the difference between the main rotation speed and the sub rotation speed changes is detected by the rotation state detection means without increasing the decrease offset from the beginning. In the offset adjusting means, the decreasing offset is changed in such a direction as to absorb the change in the difference.

  For this reason, even if the reduction offset is made small, the sub rotational speed does not exceed the main rotational speed even though there is no failure, and the main rotational speed can always be used for control. When the main rotational speed sensor fails, a large difference in rotational speed is less likely to occur at the switching timing from the main rotational speed to the sub rotational speed as compared with the case where the decrease offset is increased as a fixed value.

  Therefore, not only can the stability of the rotational driving force source control be maintained at the normal time due to the reduced offset, but also the stability of the rotational driving force source control can be maintained even when the main rotational speed sensor fails.

  The rotational speed detection backup device according to claim 2 is a main rotational speed sensor provided for a measurement target rotation shaft, and has a higher response than the main rotation speed sensor, and the measurement target rotation shaft or the measurement target. A sub-rotation speed sensor provided for an axis interlocking with the rotation axis, and obtained by detection of the main rotation speed of the measurement target rotation axis and the sub-rotation speed sensor obtained by detection of the main rotation speed sensor. A rotational speed detection backup device that performs backup in the event of failure of any rotational speed sensor by selecting a higher rotational speed from the secondary rotational speeds of the measurement target rotational shaft, wherein the secondary rotation Responsiveness reduction means for adding a responsiveness reduction process for making the responsiveness of the speed equal to the main rotational speed is added to the auxiliary rotational speed.

  In this way, the responsiveness reducing means lowers the responsiveness of the auxiliary rotational speed to make it equal to the main rotational speed. From this, even if a sub-rotation speed sensor with higher response than the main rotation speed sensor is used, if the rotation change of the rotation axis to be measured occurs, does the difference between the main rotation speed and the sub-rotation speed not occur? Little if any.

  Therefore, the higher of the main rotation speed and the sub rotation speed is selected, and even when switching between the main rotation speed and the sub rotation speed occurs in the normal state, it is possible to switch with almost no step and the response. Therefore, the stability of the rotational driving force source control can be maintained.

Further, even when the main rotational speed sensor fails, since no decrease offset is used, there is almost no drop at the timing of switching from the main rotational speed to the sub rotational speed.
Therefore, the stability of the rotational driving force source control can be maintained both when the main rotational speed sensor is normal and when it fails.

  According to a third aspect of the present invention, there is provided the rotational speed detection backup device according to the second aspect, wherein the responsiveness reducing means increases the degree of responsiveness reduction by the responsiveness reduction process in a region where the time change of the sub rotational speed is positive. In the region where the time change of the sub rotation speed is negative, the degree of responsiveness reduction by the responsiveness reduction process is reduced.

  Thus, by adjusting the responsiveness according to the positive / negative of the temporal change of the sub rotation speed, the sub rotation speed can always be lower than the main rotation speed when the main rotation speed sensor is normal. When the main rotational speed sensor fails, the control can be continued by switching to the sub rotational speed with no step or small step.

As a result, the stability of the rotational driving force source control can be effectively maintained regardless of whether the main rotational speed sensor is normal or malfunctioning.
According to a fourth aspect of the present invention, in the backup device for detecting rotational speed according to the third aspect, the responsiveness reducing means responds by the responsiveness lowering process as the temporal change is larger in a positive region of the secondary rotational speed. The degree of responsiveness reduction is increased, and in a region where the temporal change in the auxiliary rotation speed is negative, the degree of responsiveness reduction by the responsiveness reduction process is reduced as the time change is smaller.

As a result, the stability of the rotational driving force source control can be more effectively maintained regardless of whether the main rotational speed sensor is normal or malfunctioning.
According to a fifth aspect of the present invention, in the backup rotational speed detection backup device according to any one of the second to fourth aspects, the sub rotational speed of the measurement target rotational shaft obtained from the detection value of the secondary rotational speed sensor or the responsiveness reducing means. And a sub-rotational speed sensor decreasing offset means for adding a decreasing offset to the sub-rotating speed after the responsiveness lowering process is applied.

  In addition, you may add the said subrotation speed sensor reduction | decrease offset means with respect to the structure in any one of the said Claims 2-4. This ensures that the main rotational speed can be used for control when normal, and the reduction offset can be reduced by the presence of the response reduction means, so when the main rotational speed sensor fails, it switches to the sub rotational speed with a small step. Control can be continued. As a result, the stability of the rotational driving force source control can be maintained regardless of whether the main rotational speed sensor is normal or malfunctioning.

  The rotational speed detection backup device according to claim 6 is the backup rotational speed detection apparatus according to claim 5, wherein the main rotational speed and the sub rotational speed before or after the decrease offset by the sub rotation speed sensor decreasing offset means are reduced. And a rotation state detection means for detecting a rotation state of the rotation shaft to be measured, and the rotation state detection means detects the rotation state in a direction to absorb the change in the difference. An offset adjusting means for changing the decrease offset is provided.

  The rotation state detecting means and the offset adjusting means may be added to the configuration of the fifth aspect. As a result, a smaller offset is sufficient, so that when the main rotational speed sensor fails, the control can be continued by switching to the sub rotational speed with a smaller step. As a result, the stability of the rotational driving force source control can be effectively maintained regardless of whether the main rotational speed sensor is normal or malfunctioning.

  The rotational speed detection backup device according to claim 7, wherein the rotation shaft to be measured is an output shaft of the rotational driving force source or a torque converter that mediates transmission of the rotational driving force of the rotational driving force source. The rotation state detection means detects the rotation state of the measurement target rotation shaft based on the accelerator operation amount.

  When such an output shaft is used for rotational driving force source control by detecting its rotational speed as a measurement target rotational axis, the rotational state of this rotational speed changes depending on the amount of accelerator operation. For this reason, the rotation state detecting means can easily detect the rotation state of the rotation shaft to be measured based on the accelerator operation amount. And the stability of rotational drive force source control can be easily maintained because an offset adjustment means changes a reduction | decrease offset based on the rotation state detected in this way.

  The rotational speed detection backup device according to claim 8, wherein, in claim 7, when the magnitude of the accelerator operation amount or the increase speed of the accelerator operation amount is greater than a reference value, the rotation state detection means It is assumed that the rotation state of the rotation shaft to be measured in which the difference between the main rotation speed and the sub rotation speed before or after the decrease offset by the sub rotation speed sensor decrease offset means changes. It is characterized by.

  Specifically, it is possible to determine the rotation state of the measurement target rotating shaft in which the difference between the main rotation speed and the sub rotation speed changes from the accelerator operation amount in this way, to appropriately change the decrease offset, and to control the rotational driving force source control. Stability can be maintained.

  According to a ninth aspect of the present invention, in the rotational speed detection backup device according to the first or sixth aspect, the measurement target rotational shaft is an output shaft of a vehicle rotational driving force source, and the rotational state detecting means is in a vehicle braking state. Based on the rotation state of the rotation shaft to be measured in which the difference between the main rotation speed and the sub rotation speed before the sub-offset by the sub-rotation speed sensor reduction offset means or the sub-rotation speed after the reduction offset changes. It is characterized by detecting.

  When the rotation shaft to be measured is the output shaft of the vehicle rotational driving force source, the rotational speed varies depending on the vehicle braking state. Therefore, it is possible to easily detect the rotation state of the rotation shaft to be measured based on the vehicle braking state, and to easily maintain the stability of the rotational driving force source control by changing the decrease offset based on this rotation state. be able to.

  According to a tenth aspect of the present invention, in the ninth aspect, the rotational state detecting means is configured to detect the main rotational speed when the vehicle braking operation amount or the vehicle braking magnitude is larger than a reference value. The rotation speed of the measurement target rotating shaft changes in a difference between the sub rotation speed before the decrease offset by the sub rotation speed sensor decrease offset means or the sub rotation speed after the decrease offset.

  Specifically, by determining the amount of vehicle braking operation or the magnitude of vehicle braking in this way, it is possible to determine the rotation state of the measurement target rotating shaft in which the difference between the main rotation speed and the sub rotation speed changes, and appropriately The decrease offset can be changed, and the stability of the rotational driving force source control can be maintained.

  In the rotational speed detection backup device according to claim 11, in claim 9, the rotational state detection means detects which of a plurality of regions corresponds to the amount of vehicle braking operation or the magnitude of vehicle braking, and The offset adjusting means sets the decreasing offset for each region.

  In this way, by setting a decrease offset for each region with respect to the amount of vehicle braking operation or the magnitude of vehicle braking, the decrease offset can be appropriately changed according to the size of the vehicle braking operation amount or the size of vehicle braking, and the rotation The stability of the driving force source control can be maintained.

  According to a twelfth aspect of the present invention, there is provided a rotational speed detection backup device according to the first aspect, wherein the sub rotational speed is more responsive than the main rotational speed, and the rotational state detecting means detects the time of the sub rotational speed. When the change is larger than a reference change, the difference between the main rotation speed and the sub rotation speed before or after the decrease offset by the sub rotation speed sensor decrease offset means changes. The rotating shaft is in a rotating state.

  Thus, when the sub rotational speed is more responsive, if the time change of the sub rotational speed is large, the difference between the main rotational speed and the sub rotational speed tends to change. Therefore, by comparing the time change of the sub rotation speed with the reference change, it is possible to easily detect the rotation state of the rotation axis to be measured, and it is easy to improve the stability of the rotational driving force source control by changing the decrease offset. Can be maintained.

[Embodiment 1]
FIG. 1 is a schematic block diagram of a drive system and a control system of a vehicle to which the above-described invention is applied. An engine (gasoline engine, diesel engine, hybrid engine, etc.) 2 mounted on the vehicle as a vehicle rotational driving force source is connected to a speed change mechanism 4, and an output shaft 4 a of the speed change mechanism 4 is connected via a differential 6. The left and right drive wheels 8 and 10 are connected.

  The transmission mechanism 4 includes a torque converter 12 and a continuously variable transmission (hereinafter abbreviated as CVT) 14. The shift state in the CVT 14 is controlled by a continuously variable transmission electronic control unit (hereinafter abbreviated as CVT-ECU) 16. The CVT-ECU 16 receives the shift signal SHFT from the shift position sensor 18, the rotation speed signal NP from the input side rotation speed sensor 14a of the CVT 14, the rotation speed signal NS from the output side rotation speed sensor 14b of the CVT 14, and the turbine rotation speed sensor of the torque converter 12. The rotational speed signal NT is input from 12a.

  The operating state of the engine 2 is controlled by an engine control electronic control unit (hereinafter abbreviated as EG-ECU) 20. The EG-ECU 20 generates an accelerator opening ACCP (corresponding to the accelerator operation amount) signal indicating the operation amount of the accelerator pedal 22 detected by the accelerator opening sensor 22a, a rotation signal of the crankshaft 2a detected by the engine speed sensor 24, and the like. You are typing.

  A brake control electronic control unit (hereinafter abbreviated as BS-EC) 26 inputs a signal obtained by detecting the depression state of the brake pedal 28 by the brake switch 28a or the depression force sensor 28b.

  These CVT-ECU 16, EG-ECU 20 and BS-ECU 26 exchange data with each other and use them for their respective controls. As a result, the CVT-ECU 16 executes the shift control of the CVT 14 and the lock-up control for the torque converter 12. The EG-ECU 20 controls the operating state of the engine 2 by adjusting the throttle opening, the fuel injection amount, and the like. The BS-ECU 26 controls the braking force of the vehicle by adjusting the hydraulic pressure for the brake master cylinder.

Here, the rotational speed detection backup process performed by the CVT-ECU 16 as the rotational speed detection backup device in the control executed by the CVT-ECU 16 will be described.
2 shows a flowchart of the rotational speed detection backup process, and FIG. 3 shows a flowchart of the offset adjustment process. These processes are processes for backing up the detection of the input side rotational speed sensor 14a, and are interrupted at a constant time period.

  The rotational speed detection backup process (FIG. 2) will be described. When this process is started, first, the input side rotational speed NP (rpm) of the CVT 14 obtained by the input side rotational speed sensor 14a is read into the work memory in the CVT-ECU 16 (S102). Next, the turbine rotational speed NT (rpm) of the torque converter 12 obtained by the turbine rotational speed sensor 12a is read into the work memory in the CVT-ECU 16 (S104).

Then, as shown in Expression 1, a reduction offset process is performed on the turbine rotational speed NT, and the post-offset turbine rotational speed NToffset is calculated (S106).
[Formula 1] NToffset <-NT-D
Here, the decrease offset D is a decrease offset value set in an offset adjustment process (FIG. 3) described later.

Next, it is determined whether or not Expression 2 is satisfied (S108).
[Formula 2] NP ≧ NToffset
That is, it is determined whether or not the input side rotational speed NP is equal to or higher than the post-offset turbine rotational speed NToffset.

  If NP ≧ NToffset (yes in S108), the value of the input side rotational speed NP is set as it is as the control input side rotational speed NPa actually used for control as shown in Expression 3 (S110).

[Formula 3] NPa ← NP
If NP <NToffset (no in S108), the value of the post-offset turbine rotational speed NToffset is set to the control input rotational speed NPa actually used for control as shown in Expression 4 (S112).

[Formula 4] NPa ← NToffset
Thus, the present process is temporarily exited. Thereafter, the above-described processing is repeated every control cycle.

  Next, offset adjustment processing (FIG. 3) will be described. When this process is started, first, a vehicle driving state is detected (S152). Here, data that can capture the rotation state of the crankshaft 2a or the input shaft 14c of the CVT 14 (which is also the output shaft of the torque converter 12) is acquired by a driver operation (accelerator operation) on the accelerator pedal 22.

  Examples of this data include the accelerator opening ACCP, the acceleration speed of the accelerator opening ACCP, the rotational acceleration of the engine rotational speed NE, and the rotational acceleration of the turbine rotational speed NT, and any one of these data is acquired. .

  Next, based on the vehicle operating state thus detected, it is determined whether or not the post-offset turbine rotational speed NToffset approaches the input-side rotational speed NP (S154). This determination is equivalent to the determination as to whether or not the difference between the input side rotational speed NP and the turbine rotational speed NT changes (here, the upward separation of the turbine rotational speed NT). Therefore, step S154 may determine whether or not the turbine rotational speed NT deviates upward from the input side rotational speed NP.

  Here, in the present embodiment, it is assumed that the turbine rotational speed sensor 12a is more responsive to the rotational speed change than the input side rotational speed sensor 14a. When the rotational speed of the engine 2 is stable, NT = NP, and the post-offset turbine rotational speed NToffset is different from the input-side rotational speed NP by a decrease offset D according to the equation (1). Therefore, at the time of such stabilization, if at least the input side rotational speed sensor 14a is normal, the relationship of the above formula 2 is satisfied even if the decrease offset D is small.

  However, when the rotational speed of the engine 2 increases, the turbine rotational speed NT detected by the turbine rotational speed sensor 12a in the early stage of the increase becomes abrupt as compared with the input side rotational speed NP.

  For this reason, if the reduction offset D is fixed to be small, the post-offset turbine rotation speed NToffset cannot temporarily maintain the difference of the reduction offset D with respect to the input side rotation speed NP. That is, the post-offset turbine rotational speed NToffset approaches the input-side rotational speed NP, and in some cases, exceeds the input-side rotational speed NP, and there is a possibility that the expression 2 is not satisfied.

  As described above, the operating state in which the post-offset turbine rotational speed NToffset may approach the input-side rotational speed NP and exceed the input-side rotational speed NP is a case where any of the following conditions is satisfied.

1. The accelerator opening ACCP is larger than the reference opening.
2. The increasing speed of the accelerator opening ACCP is larger than the reference increasing speed.
3. The rotational acceleration of the engine rotational speed NE detected by the engine rotational speed sensor 24 or the turbine rotational speed NT detected by the turbine rotational speed sensor 12a is larger than the reference rotational acceleration.

Here, the reference opening, the reference increase speed, and the reference rotational acceleration are determination reference values obtained in advance by experiments or simulation calculations.
If any of the conditions 1 to 3 is satisfied, it is determined that the post-offset turbine rotational speed NToffset approaches the input-side rotational speed NP and exceeds the input-side rotational speed NP. The

  If none of the above conditions 1 to 3 is satisfied, even if the post-offset turbine rotational speed NToffset approaches a difference less than the decrease offset D with respect to the input-side rotational speed NP, there is a possibility that the input-side rotational speed NP will be exceeded. If not, it is determined as no in step S154.

  As described above, when it is determined to be no in step S154, the initial value Dbase is set to the decrease offset D as shown in Equation 5 (S158). That is, the value of the decrease offset D is kept small.

[Formula 5] D ← Dbase
When there is a possibility that the turbine rotational speed NToffset after offset may exceed the input side rotational speed NP (yes in S154), the initial value is obtained by adding the decreased offset increase value dd to the decreased offset D as shown in Expression 6. A value larger than Dbase is set (S156).

[Formula 6] D ← Dbase + dd
By increasing the decrease offset D in this way, in step S106 of the above-described rotational speed detection backup process (FIG. 2), the offset turbine rotational speed NToffset is normal (FIG. 3: S154: no) , S158).

  The decreased offset increase value dd is set to a value such that the post-offset turbine rotational speed NToffset does not exceed the input-side rotational speed NP even when any of the above conditions 1 to 3 is satisfied. The value of the decrease offset increase value dd is obtained by experiment or simulation calculation.

  Therefore, if the input side rotational speed sensor 14a does not break down, the formula 2 is satisfied even if the rotational speed of the engine 2 is not stable. That is, even if the turbine rotational speed NToffset after offset temporarily approaches the input-side rotational speed NP due to the driver's operation or the like, it does not exceed.

  Therefore, if the input side rotational speed sensor 14a does not break down, the formula 2 is always satisfied in step S108 of the rotational speed detection backup process (FIG. 2) (yes in S108). As a result, the state (S110) in which the input side rotational speed NP detected by the input side rotational speed sensor 14a is set as shown in the equation 3 is maintained for the control input side rotational speed NPa.

  If the input side rotational speed sensor 14a fails, the value of the input side rotational speed NP is greatly reduced. For example, “0” is output due to disconnection or the like. In this case, NP <NToffset is satisfied (no in S108), and the post-offset turbine rotational speed NToffset is set as the control input rotational speed NPa as shown in Equation 4 (S112). Thus, the detection of the input side rotational speed sensor 14a can be backed up by the turbine rotational speed sensor 12a.

An example of the control of the present embodiment is shown in the timing charts of FIGS.
In the timing chart of FIG. 4, when the acceleration operation of the driver is performed (t0) and the increase speed of the accelerator opening ACCP becomes larger than the reference increase speed (t1), the turbine rotational speed NToffset after the offset is reduced more than before. Decrease by D minutes. Thereafter, when the increase speed of the accelerator opening ACCP becomes smaller than the reference increase speed (t2), the turbine rotational speed NToffset after offset returns to the initial value Dbase.

  As described above, the response of the turbine rotational speed sensor 12a is higher than that of the input side rotational speed sensor 14a. Therefore, the offset turbine rotational speed NToffset based on the turbine rotational speed NT rapidly increases before the input-side rotational speed NP with respect to the rotational speed increase of the input shaft 14c due to the increase in the accelerator opening ACCP. To do. Therefore, unless the post-offset turbine rotational speed NToffset is further reduced by the decreased offset increase value dd, the post-offset turbine rotational speed NToffset exceeds the input-side rotational speed NP as indicated by the broken line in FIG.

  However, in the present embodiment, in such a period (t1 to t2), the post-offset turbine rotational speed NToffset is further reduced by the decreased offset increase value dd from the initial value Dbase. This can prevent the post-offset turbine rotational speed NToffset from exceeding the input side rotational speed NP. Therefore, the state where the value of the input side rotational speed NP is set as the control input side rotational speed NPa (S110) continues.

  In the timing chart of FIG. 5, a failure occurs in the input side rotational speed sensor 14a (t10), and the detected value of the input side rotational speed NP becomes 0 rpm. At this time, since NP <NToffset (FIG. 2: no in S108), the offset turbine rotational speed NToffset is set as the control input rotational speed NPa (S112). Therefore, failure of the input side rotational speed sensor 14a can be backed up by the turbine rotational speed sensor 12a.

  In the configuration described above, the relationship with the claims is that the input shaft 14c of the CVT 14 corresponds to the rotation shaft to be measured, the input side rotation speed sensor 14a corresponds to the main rotation speed sensor, and the turbine rotation speed sensor 12a corresponds to the sub rotation speed sensor. . The CVT-ECU 16 corresponds to a sub rotation speed sensor decrease offset unit, a rotation state detection unit, and an offset adjustment unit. Of the processes executed by the CVT-ECU 16, step S106 in FIG. 2 is the process as the sub rotational speed sensor decrease offset means, steps S152 and S154 in FIG. 3 are the processes as the rotation state detecting means, and step S156 is the offset adjustment. It corresponds to processing as means.

According to the first embodiment described above, the following effects can be obtained.
(I). When the rotation state of the input shaft 14c in which the difference between the input side rotational speed NP and the turbine rotational speed NT or the offset turbine rotational speed NToffset changes is detected by the offset adjustment process (FIG. 3) (yes in S154) ), Equation 6 is executed. Thus, even if the decrease offset D is not increased from the beginning, the decrease offset D is changed to the increase side by the decrease offset increase value dd in a direction to absorb the change in the difference in the rotation state (S156). ). Therefore, it is possible to prevent the post-offset turbine rotational speed NToffset from exceeding the input-side rotational speed NP even though it is not a failure of the input-side rotational speed sensor 14a.

  Compared with the case where the decrease offset D is always increased, the switching timing from the input-side rotational speed NP to the post-offset turbine rotational speed NToffset when the input-side rotational speed sensor 14a fails (FIG. 5: t10) is large. It becomes difficult to produce a drop in rotational speed.

  Therefore, when the input side rotational speed sensor 14a is normal, the input side rotational speed NP is set to the control input side rotational speed NPa, so that the stability of the engine control can be maintained. Therefore, engine control stability can be maintained.

  (B). The change in the rotation speed of the input shaft 14c of the CVT 14 reflects the change in the rotation speed of the crankshaft 2a via the torque converter 12. Therefore, the change in the rotational speed of the input shaft 14c of the CVT 14 can be easily detected in the acceleration state of the accelerator opening ACCP and its increasing speed, or the engine rotational speed NE and the turbine rotational speed NT. On the basis of this detection, the decrease offset D can be appropriately changed, so that the stability of the engine control can be easily maintained.

  (C). Since the turbine rotational speed sensor 12a is more responsive than the input rotational speed sensor 14a, if the rotational speed change on the turbine rotational speed NT side is large, the input rotational speed NP and the offset turbine rotational speed NToffset (or the turbine) The difference from the rotational speed NT) changes. Specifically, if the increase in the rotational speed on the turbine rotational speed NT side is large, the difference between the input-side rotational speed NP and the post-offset turbine rotational speed NToffset becomes small. Therefore, by comparing and determining the rotational acceleration of the turbine rotational speed NT and the reference rotational acceleration, the rotational state of the input shaft 14c of the CVT 14 can be easily detected, and the reduction offset D can be appropriately changed based on this detection, thereby stabilizing engine control. Sex can be easily maintained.

[Embodiment 2]
In this embodiment, instead of the rotation speed detection backup process (FIG. 2) and the offset adjustment process (FIG. 3) of the first embodiment, the rotation speed detection backup process shown in FIG. ing. Other configurations are the same as those of the first embodiment. Therefore, description will be made with reference to FIG.

  When the rotational speed detection backup process (FIG. 6) is started, first, the input rotational speed NP (rpm) obtained by the input rotational speed sensor 14a is read (S202), and the turbine rotational speed sensor 12a. The obtained turbine rotation speed NT (rpm) is read (S204). The processes in these steps S202 and 204 are the same as those in steps S102 and S104 in FIG.

  Then, as shown in Expression 7, the response responsiveness lowering process Fexp for making the responsiveness equivalent to the input side rotational speed NP is executed with respect to the turbine rotational speed NT. Calculated (S206).

[Formula 7] NTexp ← Fexp (NT)
Here, the responsiveness lowering process Fexp is, for example, a first-order lag process or a moving average process with respect to the turbine rotational speed NT. This is a process of adjusting to the same level as NP.

Next, it is determined whether or not Expression 8 is satisfied (S208).
[Formula 8] NP ≧ NTexp
That is, it is determined whether or not the input side rotational speed NP is equal to or higher than the low response turbine rotational speed NTexp.

  If NP ≧ NTexp (yes in S208), as shown in Expression 9, the value of the input side rotational speed NP is set as it is to the control input side rotational speed NPa actually used for control (S210).

[Formula 9] NPa ← NP
If NP <NTexp (no in S208), the value of the low-response turbine rotational speed NTexp is set to the control input rotational speed NPa actually used for control as shown in Expression 10 (S212).

[Formula 10] NPa ← NTexp
Thus, the present process is temporarily exited. Thereafter, the above-described processing is repeated every control cycle.

  In the configuration described above, the relationship with the claims is that the input shaft 14c of the CVT 14 corresponds to the rotation shaft to be measured, the input side rotation speed sensor 14a corresponds to the main rotation speed sensor, and the turbine rotation speed sensor 12a corresponds to the sub rotation speed sensor. . The CVT-ECU 16 corresponds to responsiveness reducing means. Of the processing executed by the CVT-ECU 16, step S206 in FIG. 6 corresponds to processing as responsiveness reduction means.

According to the second embodiment described above, the following effects can be obtained.
(I). By reducing the responsiveness of the turbine rotational speed NT, which is the sub rotational speed, and setting it as the low-response turbine rotational speed NTexp by the processing of step S206 in FIG. 6, it is equivalent to the input side rotational speed NP, which is the main rotational speed. Responsiveness. Therefore, even if the rotational change of the input shaft 14c of the CVT 14 that is the measurement target rotational shaft occurs, the difference between the input side rotational speed NP and the low-response turbine rotational speed NTexp does not occur or is small.

  Therefore, in a state where the higher one is selected between the input side rotational speed NP and the low response turbine rotational speed NTexp (S208 to S212), the input side rotational speed NP and the low response are reduced when the input side rotational speed sensor 14a is normal. Even if switching occurs between the turbine rotation speed NTexp and the turbine rotation speed NTexp, it can be switched with almost no step. For this reason, engine control stability can be maintained.

  Furthermore, even when the input side rotational speed sensor 14a fails, the present embodiment does not use a reduction offset, so that a large drop occurs at the timing when the input side rotational speed NP is switched to the low response turbine rotational speed NTexp. There is no. Therefore, the stability of engine control can be maintained both during normal operation and during failure.

[Embodiment 3]
In the present embodiment, in addition to the rotational speed detection backup process (FIG. 6) of the second embodiment, the responsiveness adjustment process shown in FIG. 7 is further interrupted and executed at regular time intervals. Other configurations are the same as those of the second embodiment. Therefore, description will be made with reference to FIG.

  The responsiveness adjustment process (FIG. 7) adjusts the responsiveness of the low-response turbine rotational speed NTexp obtained in step S206 of the rotational speed detection backup process (FIG. 6).

  When the responsiveness adjustment process (FIG. 7) is started, first, the time change of the turbine rotational speed NT is calculated with one control cycle as a time unit (S352). That is, as shown in Expression 11, the turbine rotational speed that is the difference between the turbine rotational speed NT detected by the turbine rotational speed sensor 12a in the current control cycle and the turbine rotational speed NTold detected in the previous control cycle. A time change amount dNT is calculated.

[Formula 11] dNT ← NT-NTold
Next, based on the turbine rotational speed time variation dNT, processing Fnt for setting responsiveness (for example, time constant, weighting) is executed based on the relationship shown in FIG. 8, for example, the relationship shown in the map (S354). . In FIG. 8, the response is set to level E when the turbine rotational speed time variation dNT = 0 (rpm / 1 control cycle). Level E is a level equivalent to the input side rotational speed NP described in the second embodiment. On the side where the turbine rotational speed change amount dNT <0, that is, on the side where the turbine rotational speed NT decreases, the response level Max is set as the upper limit, and the higher the degree of decrease, the higher the response is set. On the side where the turbine rotational speed change amount dNT> 0, that is, on the side where the turbine rotational speed NT increases, the response level Min is set as the lower limit, and the lower the response, the lower the response.

  As a result, when the rotational speed of the input shaft 14c increases, the response of the low-response turbine rotational speed NTexp becomes lower than the input-side rotational speed NP, and the delayed response of the turbine rotational speed lags behind the increase of the input-side rotational speed NP. NTexp will rise. However, when the rotational speed of the input shaft 14c is reduced, the response of the low-response turbine rotational speed NTexp is higher than the input-side rotational speed NP, and the low-response turbine rotational speed NTexp is set before the decrease of the input-side rotational speed NP. Will be reduced. Therefore, if the input side rotational speed sensor 14a is normal, the state of the input side rotational speed NP ≧ the low response turbine rotational speed NTexp is always maintained.

  An example of the control of the present embodiment is shown in the timing chart of FIG. As shown in the figure, if the input side rotational speed sensor 14a is normal (before t20), the low response turbine rotational speed NTexp is always less than or equal to the input side rotational speed NP, and the control input side rotational speed NPa is always input side rotation. A speed NP is set. When the input side rotational speed sensor 14a breaks down and the output is greatly reduced (t20), after that (from t20), the low response turbine rotational speed NTexp is set as the control input side rotational speed NPa.

  In the configuration described above, the relationship with the claims is that the input shaft 14c of the CVT 14 corresponds to the rotation shaft to be measured, the input side rotation speed sensor 14a corresponds to the main rotation speed sensor, and the turbine rotation speed sensor 12a corresponds to the sub rotation speed sensor. . The CVT-ECU 16 corresponds to responsiveness reducing means. Of the processes executed by the CVT-ECU 16, step S206 and the responsiveness adjusting process (FIG. 7) in FIG. 6 correspond to the process as the responsiveness reducing means.

According to the third embodiment described above, the following effects can be obtained.
(I). As shown in FIG. 8, in the time change of the turbine rotational speed NT, the response of the low-response turbine rotational speed NTexp is increased more on the deceleration side than on the acceleration side. Specifically, the deceleration side has a higher response than the input side rotational speed NP corresponding to the magnitude of deceleration, and the acceleration side has a response lower than the input side rotational speed NP corresponding to the magnitude of acceleration. Yes. For this reason, if the input side rotational speed sensor 14a is normal, the low-response turbine rotational speed NTexp can always be made smaller than the input side rotational speed NP even when the rotational speed of the input shaft 14c varies.

Therefore, the stability of the rotational driving force source control can be effectively maintained.
[Embodiment 4]
In the present embodiment, instead of the rotational speed detection backup process (FIG. 6) of the second embodiment, the rotational speed detection backup process shown in FIG. 10 is interrupted and executed at regular intervals. Other configurations are the same as those of the second embodiment. Therefore, description will be made with reference to FIG.

  Steps S402, S404, and S408 to S412 of the rotational speed detection backup process (FIG. 10) are the same processes as steps S202, S204, and S208 to S212 of the rotational speed detection backup process (FIG. 6). The difference is that, instead of step S206 in which the processing of equation 7 is performed, equation 12 or equation 13 is executed in step S406.

[Formula 12] NTexp ← Fexp (NT) − D
[Formula 13] NTexp ← Fexp (NT-D)
In other words, in this expression 12 or expression 13, compared to the expression 7, the required low-response turbine rotation speed NTexp is reduced by the decrease offset D for Fexp (NT) or the decrease offset D for the turbine rotation speed NT. It is calculated in a state where the minute reduction process has been performed. The decrease offset D is set to a constant value here.

  In the configuration described above, the relationship with the claims is that the input shaft 14c of the CVT 14 corresponds to the rotation shaft to be measured, the input side rotation speed sensor 14a corresponds to the main rotation speed sensor, and the turbine rotation speed sensor 12a corresponds to the sub rotation speed sensor. . The CVT-ECU 16 corresponds to responsiveness reducing means and auxiliary rotational speed sensor decreasing offset means. Of the processing executed by the CVT-ECU 16, step S406 in FIG. 10 corresponds to processing as responsiveness reduction means and auxiliary rotational speed sensor reduction offset means.

According to the fourth embodiment described above, the following effects can be obtained.
(I). By the process of step S406 in FIG. 10, the response of the turbine rotation speed NT, which is the sub rotation speed, is reduced and the decrease by the decrease offset D is also executed to calculate the low response turbine rotation speed NTexp. As a result, the low-response turbine rotational speed NTexp is made to have a response equivalent to the input-side rotational speed NP, which is the main rotational speed, and further lower than the input-side rotational speed NP. Therefore, even if the rotational speed of the input shaft 14c of the CVT 14 that is the measurement target rotational shaft changes, the low-response turbine rotational speed NTexp can always be a value smaller than the input-side rotational speed NP.

  Accordingly, when the input side rotational speed sensor 14a is normal, the input side rotational speed NP is always set to the control input side rotational speed NPa (yes in S408, S410), so that the stability of the engine control can be maintained.

  Further, since the low-response turbine rotational speed NTexp has the same responsiveness as the input-side rotational speed NP, even if the decrease offset D which is a fixed value is small, if the input-side rotational speed sensor 14a is normal, the rotational fluctuation Even in such a case, the low response turbine rotational speed NTexp shows a value less than the input side rotational speed NP. For this reason, even when the input side rotational speed sensor 14a fails, a large rotational speed drop is unlikely to occur, and the stability of engine control can be maintained.

[Embodiment 5]
In the present embodiment, unlike the case of the first embodiment, it is assumed that the input side rotational speed sensor 14a is more responsive to a rotational speed change than the turbine rotational speed sensor 12a. Therefore, there is a possibility that the condition described in step S154 of the offset adjustment process (FIG. 3) described in the first embodiment, that is, the post-offset turbine rotational speed NToffset approaches the input-side rotational speed NP and exceeds the input-side rotational speed NP. Certain operating conditions are different. For example, in step S154, it is determined whether vehicle braking is being performed.

  When the rotational speed of the engine 2 is stable, NT = NP, and the post-offset turbine rotational speed NToffset is different from the input-side rotational speed NP by a decrease offset D according to the equation (1). However, since the input side rotational speed sensor 14a is more responsive than the turbine rotational speed sensor 12a, when the rotational speed of the engine 2 decreases, the input side rotational speed NP decreases at the initial stage of the decrease. It becomes steep compared to the speed NT.

  Therefore, the post-offset turbine rotational speed NToffset cannot maintain the difference of the decrease offset D with respect to the input-side rotational speed NP, and the input-side rotational speed NP approaches the post-offset turbine rotational speed NToffset, and in some cases, the input-side rotational speed NP. May be less than the turbine rotational speed NToffset after offset.

  Based on the difference in response between the turbine rotational speed sensor 12a and the input side rotational speed sensor 14a, in step S154, the post-offset turbine rotational speed NToffset approaches the input side rotational speed NP and is input in the vehicle braking state. A driving state that may exceed the side rotational speed NP is determined.

  As a determination of the vehicle braking state, for example, the brake switch 28a is turned on, the output of the pedal force sensor 28b is equal to or higher than the reference pedal force (in the case of the brake master cylinder pressure), an antilock brake system (ABS) is mounted. In this case, a braking state such as a state where the ABS is operated is determined. Here, the ON state of the brake switch 28a, the output value of the pedal force sensor 28b, or the operation amount of the ABS corresponds to the amount of vehicle braking operation, and the brake master cylinder pressure corresponds to the magnitude of vehicle braking. Note that the reference pedaling force and the reference pressure are obtained in advance through experiments and simulation calculations.

  If any of these conditions is satisfied, it is determined that the post-offset turbine rotational speed NToffset is in an operating state in which the input-side rotational speed NP may approach the input-side rotational speed NP (FIG. 3). : Yes in S154).

According to the fifth embodiment described above, the following effects can be obtained.
(I). Even when the input side rotational speed sensor 14a is more responsive than the turbine rotational speed sensor 12a, the post-offset turbine rotational speed NToffset approaches the input side rotational speed NP by determining the vehicle braking state. It is possible to determine an operating state that may exceed the rotational speed NP. As a result, the effect (a) of the first embodiment can be produced.

[Other embodiments]
(A). As shown in FIG. 1, the turbine rotational speed sensor 12a and the input side rotational speed sensor 14a in the above-described embodiments detect the rotational speed of the input shaft 14c of the CVT 14. As long as the rotation speed ratio is not limited to the same axis, the turbine rotation speed sensor 12a and the input-side rotation speed sensor 14a may detect rotation speeds on different axes. . Even if the rotational speeds of the respective shafts are different, the rotational speeds of the shafts on the input side rotational speed sensor 14a side are also converted to the turbine rotational speed sensor 12a by conversion using the known rotational speed ratio. Can be detected. As described above, the processing of each embodiment can be executed at this rotational speed.

(B). In the fourth embodiment, the decrease offset D may be adjusted as in the offset adjustment process (FIG. 3).
(C). In the fifth embodiment, the determination condition in step S154 includes, as a logical sum condition, “the engine speed NE detected by the engine speed sensor 24 or the turbine speed NT detected by the turbine speed sensor 12a”. May be added. "Deceleration is greater than the reference rotation deceleration."

  (D). In the first embodiment, the decrease offset increase value dd is set according to the magnitude of the accelerator opening ACCP, the magnitude of the acceleration opening ACCP, or the acceleration of the engine rotational speed NE or the turbine rotational speed NT. May be set larger.

Similarly, in the fifth embodiment, the decrease offset increase value dd may be set larger according to the reference pedaling force or the brake master cylinder pressure.
(E). In each of the above-described embodiments, the rotational speed detection backup device for the input side rotational speed sensor 14a provided in the CVT 14 has been described. In addition to this, the engine rotational speed sensor 24 that detects the engine rotational speed NE and the tachometer or cam angle sensor are combined and processed as described in each of the above embodiments, so that the engine rotational speed sensor 24 When a failure occurs, the output of the tachometer or cam angle sensor may be used.

  Further, each of the above embodiments is an example of a vehicle equipped with an internal combustion engine. However, the present invention is not limited to this. Rotation speed detection comprising a main rotation speed sensor and a sub rotation speed sensor set for other rotation shafts. It can also be applied to backup devices.

  (F). In each of the above embodiments, the sub rotation speed sensor is a rotation speed sensor already used in another system (in each of the above embodiments, a turbine rotation speed sensor for a torque converter). A speed sensor may be provided. In this case, even if an inexpensive rotational speed sensor with low responsiveness is used as the secondary rotational speed sensor, a rotational speed detection backup device that is unlikely to cause instability of control can be provided by the processing as in the fifth embodiment. . When a rotational speed sensor with high responsiveness is used as the auxiliary rotational speed sensor, a rotational speed detection backup device that hardly causes instability of control can be provided by the processing as in the first to fourth embodiments.

FIG. 2 is a schematic block diagram of a drive system and a control system in the vehicle according to the first embodiment. The flowchart of the rotational speed detection backup process which CVT-ECU of Embodiment 1 performs. 5 is a flowchart of offset adjustment processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 10 is a flowchart of rotation speed detection backup processing according to the second embodiment. 10 is a flowchart of responsiveness adjustment processing according to the third embodiment. 10 is a graph showing the contents of responsiveness setting processing Fnt used in the third embodiment. 10 is a timing chart illustrating an example of processing according to the third embodiment. 10 is a flowchart of rotation speed detection backup processing according to the fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine, 2a ... Crankshaft, 4 ... Transmission mechanism, 4a ... Output shaft, 6 ... Differential, 8, 10 ... Drive wheel, 12 ... Torque converter, 12a ... Turbine rotational speed sensor, 14 ... CVT, 14a ... Input side Rotational speed sensor, 14b ... output side rotational speed sensor, 14c ... input shaft, 16 ... CVT-ECU, 18 ... shift position sensor, 20 ... EG-ECU, 22 ... accelerator pedal, 22a ... accelerator opening sensor, 24 ... engine Rotational speed sensor 26 ... BS-ECU 28 ... Brake pedal 28a ... Brake switch 28b ... Treading force sensor

Claims (12)

A main rotation speed sensor provided for a measurement target rotation axis; and a main rotation speed sensor provided for the measurement target rotation axis or a sub-rotation speed sensor linked to the measurement target rotation axis. By selecting the higher rotation speed from the main rotation speed of the measurement target rotation shaft obtained by the detection of the sub rotation speed sensor and the sub rotation speed of the measurement target rotation shaft obtained by the detection of the sub rotation speed sensor, A rotational speed detection backup device that performs backup in the event of a malfunction of the rotational speed sensor,
A sub rotation speed sensor decrease offset means for adding a decrease offset to the sub rotation speed of the rotation shaft to be measured, which is obtained from the detection value of the sub rotation speed sensor
Rotation for detecting a rotation state of the rotation shaft to be measured in which a difference between the main rotation speed and the sub rotation speed before or after the decrease offset by the sub rotation speed sensor decrease offset means changes. State detection means;
When the rotation state is detected by the rotation state detection unit, an offset adjustment unit that changes the decrease offset in a direction to absorb the change in the difference;
A rotational speed detection backup device comprising: A main rotation speed sensor provided for the measurement target rotation axis, and a sub-rotation provided for the measurement target rotation axis or an axis linked to the measurement target rotation axis that is more responsive than the main rotation speed sensor. A rotation speed sensor, and a main rotation speed of the measurement target rotation shaft obtained by detection of the main rotation speed sensor and a sub rotation speed of the measurement target rotation shaft obtained by detection of the sub rotation speed sensor. A rotational speed detection backup device that performs backup when any rotational speed sensor fails by selecting a higher rotational speed,
A rotational speed detection backup device, comprising: responsiveness reduction means for adding a responsiveness reduction process for making the responsiveness of the secondary rotational speed equal to the primary rotational speed to the secondary rotational speed. In Claim 2, the responsiveness reducing means increases the degree of responsiveness reduction due to the responsiveness reduction process in a region where the temporal change of the secondary rotational speed is positive, and in a region where the temporal change of the secondary rotational speed is negative. A rotational speed detection backup device, wherein the degree of responsiveness reduction by the responsiveness reduction process is reduced. 4. The responsiveness reducing means according to claim 3, wherein in a region where the time change of the sub rotational speed is positive, the responsiveness reduction due to the responsiveness reduction process is increased as the time change is large, and the time of the sub rotational speed is increased. A rotational speed detection backup device characterized in that, in a region where the change is negative, the degree of responsiveness reduction by the responsiveness reduction process is reduced as the time change is smaller. 5. The sub rotational speed after adding a responsiveness lowering process in the sub rotational speed of the rotation shaft to be measured obtained from the detection value of the sub rotational speed sensor or the responsiveness reducing means according to any one of claims 2 to 4. A rotational speed detection backup device comprising sub rotational speed sensor decreasing offset means for adding a decreasing offset to the rotation speed sensor. In claim 5,
Rotation for detecting a rotation state of the rotation shaft to be measured in which a difference between the main rotation speed and the sub rotation speed before or after the decrease offset by the sub rotation speed sensor decrease offset means changes. State detection means;
When the rotation state is detected by the rotation state detection unit, an offset adjustment unit that changes the decrease offset in a direction to absorb the change in the difference;
A rotational speed detection backup device comprising: 7. The rotating shaft according to claim 1, wherein the rotation shaft to be measured is an output shaft of a rotational driving force source or an output shaft from a torque converter that mediates transmission of the rotational driving force of the rotational driving force source. Is a rotational speed detection backup device that detects a rotational state of the rotation shaft to be measured based on an accelerator operation amount. 8. The rotational state detection means according to claim 7, wherein the main rotation speed and the sub rotation speed sensor decrease offset means are provided when the magnitude of the accelerator operation amount or the increase speed of the accelerator operation amount is greater than a reference value. The rotational speed detection backup device according to claim 1, wherein the rotational speed of the measurement target rotating shaft changes in a difference between the sub rotational speed before the decrease offset due to or the sub rotational speed after the decrease offset. 7. The measurement target rotation shaft according to claim 1, wherein the measurement target rotation shaft is an output shaft of a vehicle rotational driving force source, and the rotation state detection means is configured to determine the main rotation speed and the sub rotation speed based on a vehicle braking state. A rotational speed detection backup device for detecting a rotational state of the rotation shaft to be measured in which a difference between the sub rotational speed before the reduced offset by the sensor decreasing offset means or the sub rotational speed after the reduced offset changes. 10. The rotational state detection means according to claim 9, wherein when the amount of vehicle braking operation or the magnitude of vehicle braking is greater than a reference value, the main rotational speed and the sub-rotational speed sensor reduction offset means before the offset is reduced. A rotational speed detection backup device, characterized in that it is in a rotational state of the rotating shaft to be measured where the difference from the secondary rotational speed or the secondary rotational speed after the decrease offset changes. 10. The rotational state detection means according to claim 9, wherein the rotational state detection means detects which of a plurality of areas corresponds to a vehicle braking operation amount or a magnitude of vehicle braking, and the offset adjustment means determines the decrease offset for each of the areas. A rotational speed detection backup device characterized by setting. 2. The main rotation speed according to claim 1, wherein the sub rotation speed is more responsive than the main rotation speed, and the rotation state detection means detects the main rotation speed when the time change of the sub rotation speed is larger than a reference change. And a rotation state of the rotation shaft to be measured in which a difference between the sub rotation speed before the decrease offset by the sub rotation speed sensor decrease offset means or the sub rotation speed after the decrease offset changes. Rotation speed detection backup device.

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