JP2007309429A - Failure detecting method of line oil pressure control part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a failure of a linear solenoid valve (SLT) without adding a special sensor. <P>SOLUTION: It is grasped from a change in engine load whether or not the SLT is forcibly driven or whether useless racing occurs or not in changing the gear. In the case of a system in which it is grasped from a change in engine load whether or not oil pressure supplied from the SLT is optimum to learn and control, it is grasped by the number of the occurrence of learning in the same direction in changing the gear, whereby the failure of the SLT is detected without adding a special sensor for detecting a failure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to failure detection of a linear solenoid valve (SLT) for line hydraulic control.

  The AT (automatic transmission) is a system that automatically switches to the appropriate gear with the solenoid valve for clutch according to the vehicle speed and the amount of accelerator depression, and tries to run comfortably. In this AT system, if the control is performed so that the line hydraulic pressure supplied to the clutch solenoid valve is kept at an appropriate value in accordance with the traveling speed, the clutch solenoid valve can be controlled so as to have an appropriate operating time. Shock and wear during engagement due to abnormal engine blow-up or sudden coupling of friction materials can be reduced. For this reason, there are vehicles that control line oil pressure using a linear solenoid valve (SLT) for line oil pressure control.

  Patent Document 1 shows an example of a system that adjusts the optimum line oil pressure with a controller based on signals from a throttle opening, an engine rotation sensor, a vehicle speed sensor, and the like.

  If the SLT fails, the car cannot operate normally. Since the hydraulic pressure supplied to the transmission solenoid cannot be optimally controlled in the event of an SLT failure, the time until gear engagement is too long during gear shifting, causing the engine to be idle and causing an unnecessary engine blow-up for a moment. Or a shock due to a sudden engagement of the gears, resulting in poor ride comfort and unnecessary wear of the friction material.

  Patent Document 2 discloses a patent in which an abnormality in SLT is detected by a sensor and the amount of intake air during idling is increased in order to prevent engine stall. Although a specific example of what kind of abnormality detection sensor is not shown in this document, a signal line enters the controller from the line pressure solenoid, and an abnormality is detected in the ECU based on the signal, and any sensor is replaced with SLT. An SLT abnormality is detected by adding to.

JP 2000-46171 A JP 2000-265871 A

  It is an object of the present invention to detect using a signal from a sensor already used in conventional engine control or transmission control without adding a special sensor for detecting an SLT failure.

  The line pressure control valve is forcibly driven electrically, and the failure of the valve is diagnosed by detecting a change in the engine load at that time.

  A time until the friction material of the automatic transmission is engaged or a time until the friction material is detected is detected based on a change in the engine load, and whether or not the line pressure control valve is out of order is determined based on the time.

  A failure detection method for the line pressure control valve in an automatic transmission, wherein the increase in the supply energy when increasing or decreasing the supply energy to the line pressure control valve according to the length of engagement time required for shifting at the time of shifting. Alternatively, the failure of the line pressure control valve is determined by the number of adjustments in the same direction of decrease.

  The failure of the valve for line pressure control can be detected using the sensor signal that has been used for engine control and transmission control.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing input / output signals and the like related to an engine, a transmission, and a control device (ECU) that controls the engine. The ECU includes a microcomputer, an input / output circuit, a memory, and the like (not shown). Signals from various sensors are input to the ECU, and signals are output from the ECU to a linear solenoid, a transmission solenoid, and a diagnostic lamp output unit that notifies abnormality. The transmission includes a linear solenoid valve (SLT) that controls the hydraulic pressure supplied to the transmission solenoid.
The output unit includes lighting of a MIL (Mulfunction Indicator Lamp) failure display lamp, and output of a diagnosis failure result of diagnosis.

  The various sensors include an engine speed sensor that is an engine load estimation sensor, an intake air amount sensor, and the like.

  FIG. 2 shows a cross-sectional view of a linear solenoid valve (SLT). The hydraulic pressure of OUT is controlled by a movable piece driven by electric current. The current flowing through the SLT is normally controlled by a current having a short time period of ON-OFF, and the movable piece moves to a predetermined position with the average current value to control the hydraulic pressure.

  FIG. 3 is a characteristic diagram for line hydraulic control. The oil pressure is controlled by current using SLT to supply a predetermined line oil pressure.

FIG. 4 shows changes in the engine speed when the drive current is forcibly changed when the SLT is normal when the vehicle is stopped and idling, and the engine speed at the time of failure where the SLT is fixed. Show. When the drive current is changed when the SLT is normal, the engine speed changes. However, even if the drive current is changed in the event of a failure such as sludge stuck in the solenoid, the engine speed does not change. .
FIG. 5 is a first embodiment showing a determination procedure.

  Logic for forcibly driving the SLT during idling to see if there is a predetermined change in engine load such as engine speed, etc., and determining that the SLT is abnormal if there is a predetermined change (flow chart) Indicates.

  In this embodiment, in S2, the engine rotation is stabilized under the condition that the shift lever of AT (automatic transmission) is in (P) parking, or (N) the gear is in neutral and the brake is stepped on. The linear solenoid valve current value is forcibly changed when the engine is running, and the engine load change is detected by the change in the rotational speed to determine whether or not there is an abnormality.

  Specifically, if all the measurement start conditions such as “stopped” are satisfied in S2, and if the engine speed is stable for a certain time in S3, the engine speed is first measured in S4 and the value is stored in NE0. To do. Thereafter, in S5, a time (for example, 1 to 2 seconds) forcibly energizing the linear solenoid valve is provided, the engine speed at the last moment of energization is stored in NE1, and the engine speed after the SLT forcible drive is stored. Capture the change in number (NE1-NE0). This forcible drive time is preferably set to a time from when the solenoid is driven to when the increase in the engine speed ends. After that, the waiting time at S6 is terminated, and at S7, it is checked whether or not the engine has settled at a predetermined rotational speed. If the engine is stable, the result is trusted, and at S8, the engine rotational speed is measured and stored in NE2. To do. In S9, the process proceeds to a step of determining whether or not the result data of the forced drive is to be trusted. If the engine speed has changed as a result of the forced drive, it is determined to be normal, and if not changed, it is determined to be abnormal in S10.

  After IGON (ignition on), once the determination step is passed, a measurement completion flag is set in S12, it is determined whether or not a predetermined number of measurements have been made in S1, and this measurement / determination step can be passed again during IGON. Make sure there is no. This is to prevent the driver from recognizing something abnormal as the engine speed changes when the SLT is forcibly driven.

  If it is determined that there is an abnormality, the warning lamp is turned on in S11 to prompt the driver to go to the failure repair shop, and the failure state is stored in the diagnosis.

In the present invention, the failure determination of the SLT is performed immediately after the engine is started or within a relatively short time after the operation is started, the failure state is stored in the diagnosis, and the diagnosis lamp is turned on and guided to the repair shop. Further, by analyzing the stored diagnosis information even in a repair shop or the like, it is possible to provide a method for accurately identifying the true failure site.
Also, while the forced drive is being performed and the change in engine load is measured, the setting value of the idle speed changes due to engine warming, etc., and the engine load may change, so in that case, the measurement result is not trusted, The result is not used for judgment.

  Further, if the SLT is forcibly driven every time the vehicle is stopped, the engine rotation changes unnecessarily every time. Therefore, there is a possibility that it becomes a mental stress for the driver. In this embodiment, the logic for measuring only once from the engine start is shown.

  Note that the first start condition in the flowchart of FIG. 5 starts with IGON and is subsequently executed, for example, every 16 ms in the main routine. Although not shown in the drawing, this flowchart allows time-sharing to execute other flows without waiting for the end of processing in the flow. In other words, if this flow is executed for a predetermined period of time, it is usually designed so that other processing flows also rotate. In this embodiment, this flow is executed every 16 ms, for example, and if the execution time passes, for example, 1 ms, the address and result are stored, and the continuation is executed at the next timing. In the embodiment shown in FIGS. 6 and 7, the same time sharing is generally performed. This 16 ms is an example, and there are products that are designed to be 10 times longer, for example, and products that are designed to be as short as 1/10.

  In this example, the change in the engine speed is regarded as the engine load and the measurement is performed. However, the engine load is measured based on the intake air amount of the engine, the change in the engine negative pressure or the engine delay angle, and the advance time. Is also possible. The same applies to the following embodiments.

FIG. 6 is a second embodiment showing a determination procedure, and shows a failure detection logic (flow chart) by measuring the time from the start of gear shifting to the engagement. This system determines a SLT failure while driving.
First, in S61, it is confirmed whether or not the vehicle is traveling at a constant speed, whether or not the vehicle is traveling at a constant speed, and whether or not the accelerator opening is below a certain value. When the gear shift is performed by detecting that there is a change, the time from the start to the end of the gear shift is measured by a change in engine load such as a change in the engine speed in S63, and it is determined whether or not the predetermined time is reached in S65. By doing so, it is determined whether or not the line hydraulic pressure is normal, and it is determined whether or not the SLT is operating normally. By the way, if the engagement is not completed within a predetermined time, the hydraulic pressure is low. In this case, the engine blows up unnecessarily, and it is determined in S66 that the SLT has an ON failure, and in S67, an abnormal code is stored. Turn on MIL. If the engagement is performed in an abnormally shorter time than the predetermined time, it is determined that the SLT has an OFF failure.

  The start of shifting refers to the timing of shifting determination, and the end of shifting depends on whether or not the input shaft rotation speed of the transmission, that is, the engine rotation speed, and the target rotation speed after shifting are substantially the same.

  Even at the end of measurement, if it is determined that the vehicle is not in steady running, such as when the difference between the speed before the start of measurement and the speed immediately after the end is large in S64, the measurement result is not determined.

  In the above determination, the end of engagement is determined only by the rotation speed of the input shaft on the assumption that the vehicle speed does not change if the vehicle speed is short. However, as another method of determining the end of shifting more reliably, There is also a method of determining the end of the shift based on the input shaft speed, the output shaft speed, and the gear stage.

  FIG. 7 is a third embodiment showing a failure determination procedure, and shows a logic (flow chart) for determining an SLT abnormality by observing the learning process in a system that performs learning control of the SLT pressure. This learning control system determines the SLT pressure based on the change in the input rotational speed to the transmission, performs control for optimizing them by controlling the supply current value to the SLT, and supplies the hydraulic pressure at the time of gear change of the automatic transmission To optimize. This system is designed to absorb variations in the parts that make up an automatic transmission and changes in characteristics over time.

  That is, a failure is determined when the learning control is continuously performed in the same direction for a certain number of times.

  If the control in the reverse direction is performed even once in the meantime, it is determined that the control is not in the same direction, and a predetermined value is subtracted from the cumulative number, or the determination is returned to the initial value and checked again. To do.

  Here, the determination as to whether or not the vehicle is in steady running is executed in S71, which is the same as in the second embodiment. In S72, it is confirmed that shifting is in progress, and then in S73, it is detected that learning about the SLT pressure has been performed. If the learning is continuous learning in the same direction, the number of times is set to N1 in S74. , Store in N2. If the value exceeds, for example, 10 times in S75, it is determined that the SLT is abnormal. If they are not in the same direction, the values of N1 and N2 are reset, and failure diagnosis is performed again from the beginning. In S76, it is determined whether or not N2 is high. If the pressure in S77 is high, it is determined that an SLT-ON failure (or failure tends to occur). If not, an SLT-OFF failure (or failure tends to occur) in S78. ). In S79, the abnormal code is stored and the MIL is turned on.

Block diagram of engine control and transmission control Sectional view showing an example of linear solenoid valve Linear solenoid valve Input current-Output hydraulic pressure Changes in engine speed when the drive current of the linear solenoid valve is changed during idling Failure detection flowchart Linear solenoid ON failure detection flowchart based on transmission engagement time measurement Linear solenoid failure judgment flowchart based on the number of learnings

Claims (3)

  A failure detection method comprising: diagnosing a failure of the valve by electrically forcibly driving a line pressure control valve and detecting a change in engine load at that time.   A failure detection method characterized by detecting a time until the friction material of the automatic transmission is engaged or a time until the friction material is released, and determining whether or not the line pressure control valve is failed based on the time. A method of detecting a failure of the line pressure control valve in an automatic transmission, wherein the increase in the supply energy when increasing or decreasing the supply energy to the line pressure control valve according to the length of engagement time required for shifting at the time of shifting. Alternatively, the failure detection method is characterized in that the failure of the line pressure control valve is determined by the number of adjustments in the same direction of decrease.