JP2921255B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission in which a plurality of shift ranges can be selected by electrical control.

[0002]

2. Description of the Related Art In an automatic transmission, selection of each shift range such as a forward range, a reverse range, a parking range and a neutral range is performed by switching a range switching valve (manual valve). Although the range switching valve is generally switched by manual operation, an automatic transmission having a configuration in which the switching is performed by electrical control has already been proposed.

The present applicant has also proposed a control device for an automatic transmission as shown in the specification and drawings, for example, filed in Japanese Patent Application No. 304182/1991.

In this control apparatus, a range switching valve of an automatic transmission is switched by a motor driven based on a range control signal output from a shift-by-wire control unit. The switching position of the range switching valve is detected by a change in the output voltage of a sensor using a rotary potentiometer or the like whose variable resistance value indicates a linear characteristic, and this detection signal is transmitted to the shift-by-wire control unit. It has become. That is, during the switching control of the range switching valve by the drive of the motor, the switching position of the range switching valve is always detected by the sensor, so that the automatic transmission is switched to the target shift range.

[0005]

When the detection signal of the sensor fails, the detection value (output voltage value) of the sensor changes if the signal is under the switching control of the range switching valve by driving the motor. Therefore, it is difficult to judge a failure. However, unless this fail judgment is made correctly,
The target shift range cannot be achieved. Also, when the detection signal of the sensor fails while the vehicle is traveling (while the motor and the range switching valve are stopped), if this failure is not determined, the shift range position due to an erroneous detection signal and the actual shift range of the automatic transmission. When the control for adjusting the adjustment is carelessly executed, a disadvantage such as achievement of a shift range not intended by the driver occurs.

An object of the present invention is to appropriately determine a signal failure of a range detection sensor according to whether switching control of a range switching valve is being performed and whether the range switching valve is being stopped, thereby performing appropriate fail-safe control corresponding to each of them. Is to make it possible.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a shift control device for an automatic transmission according to the present invention is configured as follows. That is, the range switching valve is switched by a motor driven based on the range control signal output from the shift-by-wire control unit, and the switching position of the range switching valve is detected by a change in the output voltage of the range detection sensor. In the shift control device for an automatic transmission configured to transmit a detection signal to the shift-by-wire control unit, the shift-by-wire control unit controls the output voltage of the range detection sensor during switching control of the range switching valve by driving the motor. When the amount of change per time exceeds a predetermined value, or when the output voltage corresponding to the switching position at that time while the range switching valve is stopped exceeds the above-described predetermined value, the range detection sensor is used. Means for determining that the signal has failed. Note that the preset “predetermined value” is a value determined in consideration of a production error of the range detection sensor or the motor, an operating environment, aging, and the like, and is not output in a normal state. Value.

[0008]

According to this configuration, during the switching control of the range switching valve by the driving of the motor, based on the detection signal input from the range detection sensor to the shift-by-wire control unit, the output voltage of this sensor per time is determined. When the change amount exceeds a predetermined value, it is determined that the sensor signal has failed. While the range switching valve is stopped, when the output voltage corresponding to the position of the range switching valve (shift range of the automatic transmission) at that time exceeds a predetermined value, it is determined that the sensor signal has failed. This enables accurate fail determination not only during stoppage of the range switching valve, but also particularly during switching control of the range switching valve, for which failure determination has been difficult.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a perspective view schematically showing a range switching valve 30 for switching a shift range of the automatic transmission and a driving system thereof. The range switching valve 30 is of a spool valve type, and is supplied with a line hydraulic pressure serving as a basic hydraulic pressure for controlling the automatic transmission. By operating the spool 30a of the range switching valve 30 in the axial direction, the discharge port is switched, and engagement and release of a friction engagement device (not shown) for setting each shift range is controlled. .

A detent lever 36 is fixed on the control shaft 32 shown in FIG. By the rotation of the control shaft 32 around the axis, the rotation of the detent lever 36 causes the range switching valve 3 to rotate.
The zero spool 30a is moved in the axial direction. The detent lever 36 has a fan shape, and a plurality of uneven portions 36a are formed on the outer periphery thereof. For one of these concave and convex portions 36a,
Roller 3 provided at end of detent spring 38
8a are selectively engaged. A detent mechanism 34 that determines the rotational position of the control shaft 32, that is, each switching position of the range switching valve 30, by these members.
Is configured.

A DC motor 50 is used as an actuator for switching the range switching valve 30. A worm 54 formed on a drive shaft 52 of the motor 50 meshes with a worm wheel 56 arranged coaxially with the control shaft 32. The end of the control shaft 32 is engaged with the boss 58 at the rotation axis of the worm wheel 56 so as to transmit the rotation. As a result, the rotation of the drive shaft 52 of the motor 50 is
The transmission is performed at a reduced speed due to the engagement between the worm wheel 4 and the worm wheel 56.

FIG. 3 shows an enlarged view of the engagement between the end of the control shaft 32 and the boss 58 of the worm wheel 56. As is apparent from this drawing, the end of the control shaft 32 is formed in a rectangular cross section, and this portion is inserted into the boss 58. The engaging portion is provided with a predetermined play amount δ with respect to the rotation transmission direction between them. That is, the play amount δ is provided in a power transmission path between the motor 50 and the range switching valve 30, and the rotational force of the worm wheel 56 associated with the drive of the motor 50 reduces the play amount δ after reducing the play amount δ. This is transmitted to the control shaft 32.

By the rotation of the control shaft 32, the range switching valve 30 is switched through the detent lever 36 as described above. At this time, in each range position of the range switching valve 30, the roller 38a of the detent spring 38
The operation of moving over one convex portion of the concave / convex portion 36a and engaging with the adjacent concave portion is repeated. Therefore, during a period from the time when the roller 38a crosses one convex portion of the concave and convex portion 36a to the time when the roller 38a reaches the concave portion, the control shaft 32 is driven by the motor 50 based on the elastic force of the detent spring 38.
Irrespective of the driving of the vehicle, the vehicle runs within the range of the play amount δ. Immediately after this self-propelled operation until the play amount δ is reduced again by the rotation of the worm wheel 56 driven by the motor 50, the control shaft 3
The rotation amount of 2, that is, the operation amount of the range switching valve 30 hardly changes.

FIG. 1 shows an electric control system diagram for selecting a shift range of the automatic transmission AT. In this drawing, a range select switch 10 is connected to an automatic transmission A.
A position switch that is switched in response to a shift lever operation by the driver to select a shift range of T (PRND, etc.) or a push switch that is directly operated by the driver.

A shift-by-wire control unit (SBW-ECU) 20 shown in FIG. 1 uses a microcomputer and stores programs necessary for switching the shift range of the automatic transmission AT and various software processes related thereto. It mainly comprises a read-only memory (ROM), a central processing unit (CPU) for executing the program, and a writable memory (RAM) for temporarily storing variables required for the program. Automatic transmission control (ECT) 22 also shown in FIG.
The automatic transmission control unit 22 can control the switching of the solenoid valve for automatic transmission in the automatic transmission AT based on the vehicle speed and the engine load (throttle opening) as is well known.

The shift-by-wire control unit 20 (hereinafter abbreviated as “SBW control unit 20”) includes a contact signal of the range select switch 10 and the range switching valve 30.
The respective detection signals from a valve sensor 12 as a range detection sensor and a neutral switch 14 for detecting the switching position are input. The SBW control unit 20
From the control signal corresponding to the contact signal from the range select switch 10 to the drive circuit 2 of the motor 50.
4, the automatic transmission control unit 22 and the range indicator 2
8, respectively.

As the valve sensor 12, as shown in FIG. 2, a rotary potentiometer or the like provided on the control shaft 32 is used, and the rotation angle of the control shaft 32 (the rotation of the range switching valve 30) is used. The electric resistance value that changes in accordance with the operation amount shows a linear characteristic, and the range switching valve 30
Is detected. The detection signal of this sensor is converted into a digital signal by the analog / digital converter 26 of FIG. 1 and input to the SBW control unit 20.

The neutral switch 14 is turned on when the switching position of the range switching valve 30 is in the neutral (N) range or the parking (P) range, and a signal thereof is input to the SBW control unit 20. The range indicator 28 is provided on the instrument panel in front of the driver's seat, and basically illuminates and displays a portion corresponding to the shift range of the automatic transmission AT.

FIG. 4 shows a change in the output voltage value U of the valve sensor 12 with respect to time t (the rotation angle of the motor 50) during the switching control of the range switching valve 30 by the driving of the motor 50. FIG. 4A shows a case where the range switching valve 30 is controlled to be switched from the drive (D) range to the P range, and FIG.
Indicates a case where the range switching valve 30 is controlled to switch from the P range to the D range. As is apparent from these drawings, the output voltage value U changes along the inclination of the predetermined angle α when the range switching valve 30 reduces the play amount δ and is interlocked with the driving of the motor 50. Further, when the range switching valve 30 self-runs in the range of the play amount δ by the function of the detent mechanism 34 at each range position,
Until the output voltage value U instantaneously changes greatly and the play amount δ is reduced again by driving the motor 50,
The output voltage value U hardly changes.

The permissible range of the output voltage value U indicated by the imaginary lines a and b in FIG. 4A is expressed by the following equation 1, respectively, and is indicated by the imaginary lines c and d in FIG. The permissible range of the output voltage value U shown is represented by Expression 2. These allowable ranges are set to determine the signal failure of the valve sensor 12.

[0021]

## EQU1 ## a = U ₀ + ΔU ₁ + αt b = U ₀ −ΔU ₂ + αt

## EQU2 ## c = U ₀ + ΔU ₁ −αt d = U ₀ −ΔU ₂ −αt

However, in Equations 1 and 2, U0
Is an output voltage value when the motor 50 not shown in FIG. 4 is not driven, ΔU1 and ΔU2 are allowable values of the output voltage value U when judging a signal failure of the valve sensor 12, and α is an output voltage. The amount of change in the value U per unit time. Therefore, in the sample example shown in FIG. 4, if the output voltage value U of the valve sensor 12 is within the range of the imaginary lines a and b in FIG. 4A, it is normal, and in FIG. If it is within the range of d, it is normal.

In the shift control device having the above-described structure, when the range select switch 10 shown in FIG. 1 is controlled to be switched, based on a control signal output from the SBW control unit 20 in accordance with the contact signal. The motor 5
0 is driven. As a result, the switching of the range switching valve 30 is controlled, and the shift range of the automatic transmission AT is selected. The switching position of the range switching valve 30 is always detected by a change in the output voltage from the valve sensor 12.

FIGS. 5 to 7 are flowcharts showing the contents of software processing by the SBW control unit 20 for determining a signal failure of the valve sensor 12. First, in step S1 of FIG. 5, it is determined whether or not shift range switching control is being performed by operating the range select switch 10. If the determination result is yes, the process proceeds to the next step S2. The process moves to step S14 in FIG. 7 to be described. In this step S2, it is determined whether or not the motor 50 is being driven. If the determination result is YES, the process proceeds to step S3 to determine whether or not the movement start flag FT of the range switching valve 30 is "1". I do.

If the result of the determination in step S3 is YES, the process proceeds to step S9 in FIG. 6, which will be described later, and if NO, the process proceeds to step S4. In this step S4, it is determined whether or not the rotation direction of the motor 50 is a direction for moving the range switching valve 30 to the P range side. If the result of this determination is yes, the process moves to step S5, where it is determined whether or not the output voltage value U of the valve sensor 12 has changed in accordance with the characteristic of FIG. 4A (U ₀ + ΔU <U). .

In step S5, U0 is the output voltage value before the start of driving of the motor 50, as described above, and ΔU is the output voltage value set in advance to determine that the motor 50 is driven. It is a change value (change amount). Therefore, if the determination result in step S5 is YES, since the range switching valve 30 has started to move in the P range direction, the process proceeds to step S6. In this step S6, the range switching valve 3
The movement start flag FT of 0 is set to “1” and the timer is started.

If the result of the determination in step S2 is NO, that is, if the motor 50 is not driven, the process proceeds to step S7, where the movement start flag FT of the range switching valve 30 is set to "0". Reset the timer. If the result of the determination in step S4 is NO, that is, if the rotation direction of the motor 50 is
Is moved to the D range side, the process proceeds to step S8. In this step S8, the valve sensor 12
Is determined according to the characteristics of FIG. 4B (U ₀ −ΔU <U). If the result of this determination is YES, since the range switching valve 30 has begun to move in the direction of the D range, the aforementioned step S
The process proceeds to 6 and the same processing as described above is executed.

Next, the failure determination control during the switching control of the range switching valve 30 will be described with reference to the flowchart of FIG. In step S9 of this drawing, it is determined again whether the rotation direction of the motor 50 is a direction for moving the range switching valve 30 to the P range side. If the result of this determination is yes, the process moves to step S10, where the valve sensor 12
It is determined whether or not the output voltage value U is within the range of the characteristics represented by the imaginary lines a and b in FIG. 4A (a <U <b). If the result of the determination in step S9 is NO, that is, if the rotation direction of the motor 50 is the direction in which the range switching valve 30 is moved to the D range side, the process proceeds to step S13. In this step S13, it is determined whether or not the output voltage value U of the valve sensor 12 is within the range of the characteristic represented by the imaginary lines c and d in FIG. 4B (c <U <d).

Step S10 or step S1
If the result of the determination in No. 3 is no, that is, if the amount of change per hour of the output voltage value U exceeds a predetermined value that is not output in a normal state, the valve is controlled during the switching control of the range switching valve 30. Since a signal failure of the sensor 12 has occurred, the flow shifts to step S11, and the failure flag FL1 during the switching control is set to "1". On the other hand, step S10 or step S13
If the determination result in step (1) is YES, it means that the detection signal of the valve sensor 12 has been determined to be normal, and the process shifts to step S12, where the fail flag FL1 during the switching control is set to "0".

Next, the failure determination control during stoppage of the range switching valve 30 will be described with reference to the flowchart of FIG. In step S14 of this drawing, it is determined that the output voltage value Ue of the valve sensor 12 at the end of the switching control of the range switching valve 30 (at the time of stop) and that the range select switch 10 has not been operated in step S1 of FIG. Whether or not the absolute value of the difference from the output voltage value U at the time is within the range of the failure determination voltage value ΔUn during non-control (| Ue −
Un | <ΔUn). If the result of this determination is NO, since the signal failure of the valve sensor 12 has occurred when the range switching valve 30 is stopped, the flow proceeds to step S15, where the failure flag FL0 at the time of non-control is set to "1". To

If the decision result in the step S14 is YES, the process shifts to a step S16 for a return decision. In step S16, it is determined whether the error of the actual output voltage value U with respect to the set voltage value Un of the valve sensor 12 determined for each shift range is within the range of the fail determination voltage value ΔUn, that is, Un− It is determined that ΔUn <Ue <Un + ΔUn. If the result of this determination is yes, the flow moves to step S17 to set the fail flag FL0 during non-control to "0". If the result of the determination in step S16 is NO, the flow shifts to another control (not shown) to continue the predetermined circulation processing.

As described above, during the switching control of the range switching valve 30, when the rate of change of the output voltage value U of the valve sensor 12 per time t exceeds a predetermined value, it is determined that the detection signal has failed. While the range switching valve 30 is stopped, when the output voltage value corresponding to the shift range at that time exceeds a predetermined value, it is determined that the detection signal has failed. As a result, accurate failure determination is performed regardless of whether the range switching valve 30 is under switching control or stopped.

An example of control when it is determined that the signal of the valve sensor 12 has failed will be described with reference to the flowchart of FIG. First failure flag FL ₀ during the non-control, it is determined whether "1" in step S50, the determination result is transferred to the next step S51 if YES. In this step S51, it is determined whether or not a contact signal for instructing a traveling range in the direction opposite to the current traveling of the vehicle from the range select switch 10 is input. If the result of this determination is YES, the process moves to step S52, where the shift range of the automatic transmission AT is switched to the N range using the detection signal of the neutral switch 14.

[0034] The case determination result in step S50 is NO and proceeds to step S53, where the control in the failure flag FL ₁ determines whether "1". If the determination result is yes, the process shifts to step S52 to perform the same processing as described above. If the result of the determination in step S53 is NO, the flow shifts to another control (not shown) to continue the predetermined circulation processing. On the other hand, if the decision result in the step S51 is NO, the process shifts to a step S54 to cancel the shift range switching control.

When the shift range of the automatic transmission AT is switched to the N range, or when the switching control is cancelled, a predetermined portion of the range indicator 28 is blinked or displayed, and a valve sensor is provided by voice from a voice navigation (not shown). It is necessary to alert the driver that the control based on the 12 signal failures has been performed.

[0036]

As described above, according to the present invention, the signal failure of the range detection sensor can be determined both during the switching control of the range switching valve and during the stop of the range switching valve. And appropriate fail-safe control according to whether the vehicle is stopped or not.

[Brief description of the drawings]

FIG. 1 is an electric control system diagram for selecting a shift range of an automatic transmission.

FIG. 2 is a perspective view showing an outline of a range switching valve of an automatic transmission and a drive system thereof.

FIG. 3 is an enlarged plan view of an engagement portion between a control shaft and a worm wheel.

FIG. 4 is a characteristic diagram showing a change in a sensor output voltage during range switching control.

FIG. 5 is a flowchart for determining the start of movement of a range switching valve.

FIG. 6 is a flowchart for determining a failure during range switching control.

FIG. 7 is a flowchart for determining a failure during non-switching control.

FIG. 8 is a flowchart illustrating control at the time of a failure determination.

[Explanation of symbols]

 12 Range detection sensor (valve sensor) 20 Shift-by-wire control unit 30 Range switching valve 50 Motor

Claims (1)

(57) [Claims] A range control valve is controlled to be switched by a motor driven based on a range control signal output from a shift-by-wire control unit, and a switching position of the range control valve is determined by a change in an output voltage of a range detection sensor. A shift control device for an automatic transmission configured to detect and transmit a detection signal to the shift-by-wire control unit, wherein the shift-by-wire control unit is configured to control the range detection sensor during switching control of a range switching valve by driving the motor. When the change amount per hour of the output voltage of the output voltage exceeds a predetermined value, or when the output voltage corresponding to the switching position at that time during the stop of the range switching valve exceeds the predetermined value, A shift control device for an automatic transmission, comprising: means for determining a signal failure of a range detection sensor.