Automatic transmission

Abstract

An automatic transmission includes a planetary gear arrangement, and a plurality of engaging elements each arranged to vary an engagement state among the rotating elements of the planetary gear arrangement in such a manner to establish a normal gear ratio set and an emergency gear ratio set excluded from the normal gear ratio set. A control section performs the following: selecting a gear from the normal gear ratio set in accordance with a running state of a vehicle under normal operating conditions; controlling the engagement state of each of the engaging elements in such a manner to shift into the selected gear; establishing, when an interlock state is detected, an escape gear by releasing one of the engaging elements needed to be applied to establish the selected gear; and identifying an incorrectly-applied engaging element in accordance with the running state of the vehicle resulting from establishing the escape gear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a skeleton diagram showing the construction of an automatic transmission provided in a first embodiment, which is adapted for a front-engine rear-drive automotive vehicle to establish seven forward gear ratios and one reverse gear ratio.

FIG. 2 is a circuit diagram showing a hydraulic circuit of a control valve unit provided in the first embodiment.

FIG. 3 is a schematic diagram showing the construction of a first pressure regulating valve provided in the first embodiment.

FIG. 4 is a schematic diagram showing the construction of a first directional control valve provided in the first embodiment.

FIG. 5 is a schematic diagram showing the construction of a second directional control valve provided in the first embodiment.

FIG. 6 is a schematic diagram showing the construction of a third directional control valve provided in the first embodiment.

FIG. 7 is a schematic diagram showing the construction of a fourth directional control valve provided in the first embodiment.

FIG. 8 is a diagram showing in tabular form a set of clutch and brake engagements required to establish each of the seven forward gear ratios and the one reverse gear ratio in the automatic transmission provided in the first embodiment.

FIG. 9 is a speed relationship diagram (lever diagram) showing the rotational speed of rotating elements of the automatic transmission provided in the first embodiment when establishing each of the seven forward gear ratios and one reverse gear ratio.

FIG. 10 is a diagram showing in tabular form a set of operational states of solenoid valves required to establish each of the seven forward gear ratios and the one reverse gear ratio in the automatic transmission provided in the first embodiment.

FIG. 11 is a flow chart showing an outline of a process of failure detection and failure handling provided in the first embodiment.

FIG. 12 is a flow chart showing a process of abnormality detection control provided in the first embodiment.

FIG. 13 is a flow chart showing a process of escape shift control provided in the first embodiment, which is carried out when it is judged that an interlock-state failure is present in the automatic transmission.

FIG. 14 is a diagram showing in tabular form a relationship among each selected gear, each possible incorrectly applied engaging element, a released engaging element corresponding to the selected gear, and a gear ratio established under such a condition.

FIG. 15 is a speed relationship diagram of the automatic transmission, in which an engaging-state failure occurs in a 2346-brake provided in the automatic transmission to change the state of speed relationship of the automatic transmission in first gear.

FIG. 16 is a speed relationship diagram of the automatic transmission, in which an engaging-state failure occurs in a front brake provided in the automatic transmission to change the state of speed relationship of the automatic transmission in second gear.

FIG. 17 is a diagram showing in tabular form a set of possible gear ratios established when a failure occurs in each selected gear.

FIG. 18 is a flow chart showing a process of escape shift control provided in the first embodiment, which is carried out when it is judged that an abnormal gear ratio failure is present in the automatic transmission.

FIG. 19 is a speed relationship diagram of the automatic transmission in 1-2 intermediate gear (1.5th gear) in the first embodiment.

FIG. 20 is a speed relationship diagram of the automatic transmission in 2-3 intermediate gear (2.5th gear) in the first embodiment.

FIG. 21 is a flow chart showing a process of escape shift control provided in the first embodiment, which is carried out when it is judged that a neutral-state failure is present in the automatic transmission.

FIG. 22 is a speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in fifth gear.

FIG. 23 is another speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in fifth gear.

FIG. 24 is a speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in sixth gear.

FIG. 25 is another speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in sixth gear.

FIG. 26 is another speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in sixth gear.

FIG. 27 is a speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in seventh gear.

FIG. 28 is another speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in seventh gear.

FIG. 29 is another speed relationship diagram of the automatic transmission, in which a neutral-state failure occurs to change the state of speed relationship of the automatic transmission in seventh gear.

FIG. 30 is a flow chart showing a process of abnormality identification control and abnormality handling shift control provided in the first embodiment.

Claims

1. An automatic transmission comprising: a planetary gear arrangement including a plurality of rotating elements, and including an input rotating element adapted to be connected to a driving source of a vehicle and an output rotating element adapted to be connected to a drive wheel set of the vehicle;a plurality of engaging elements each arranged to vary an engagement state among the rotating elements of the planetary gear arrangement in such a manner to establish at least a normal gear ratio set; anda control section configured to perform the following: selecting a gear from the normal gear ratio set in accordance with a running state of the vehicle under normal operating conditions;controlling the engagement state of each of the engaging elements in such a manner to shift into the selected gear;detecting an interlock state in which one of the engaging elements is incorrectly applied to hold the input rotating element and the output rotating element stationary;establishing, when the interlock state is detected, an escape gear by releasing one of the engaging elements needed to be applied to establish the selected gear; andidentifying the incorrectly-applied engaging element in accordance with the running state of the vehicle resulting from establishing the escape gear.

2. The automatic transmission as claimed in claim 1, wherein the control section is configured to perform the following: detecting an actual transmission gear ratio between the input rotating element and the output rotating element; andidentifying the incorrectly-applied engaging element based on comparison between the actual transmission gear ratio and the selected gear when the interlock state is detected.

3. The automatic transmission as claimed in claim 1, wherein the escape gear is included in an escape gear ratio set including at least an emergency gear ratio set excluded from the normal gear ratio set.

4. The automatic transmission as claimed in claim 1, wherein the control section is configured to complete the identifying the incorrectly-applied engaging element before stop of the vehicle after the interlock state is detected.

5. A method of controlling an automatic transmission comprising: a planetary gear arrangement including a plurality of rotating elements, and including an input rotating element adapted to be connected to a driving source of a vehicle and an output rotating element adapted to be connected to a drive wheel set of the vehicle; and a plurality of engaging elements each arranged to vary an engagement state among the rotating elements of the planetary gear arrangement in such a manner to establish at least a normal gear ratio set, the method comprising: selecting a gear from the normal gear ratio set in accordance with a running state of the vehicle under normal operating conditions;controlling the engagement state of each of the engaging elements in such a manner to shift into the selected gear;detecting an interlock state in which one of the engaging elements is incorrectly applied to hold the input rotating element and the output rotating element stationary;establishing, when the interlock state is detected, an escape gear by releasing one of the engaging elements needed to be applied to establish the selected gear; andidentifying the incorrectly-applied engaging element in accordance with the running state of the vehicle resulting from establishing the escape gear.