Automatic gear transmission

• US 6,397,696 B2
• Filed: 12/08/2000
• Issued: 06/04/2002
• Est. Priority Date: 12/08/1999
• Status: Expired due to Fees

• Current Assignee: Aishin AI Company Limited (Aisin Corp.)
• Original Assignee: Aishin AI Company Limited (Aisin Corp.)
• Inventors: Ogami, Shiro
• Primary Examiner(s): Bonck, Rodney H.
• Assistant Examiner(s): Le, David D.
• Application Number:
  US09/731,926
• Publication Number:
  US 20010003250A1
• Time in Patent Office: 543 Days
• Field of Search: 743/35, 743/36, 743/36.R, 744/731.2, 477/906
• US Class Current: 74/335
• CPC Class Codes: F16H 2059/006 Overriding automatic control
• CPC Class Codes: F16H 2059/6807 Status of gear-change operation, e.g. clutch fully engaged
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/1232 Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios
• CPC Class Codes: F16H 2061/1284 the failing part is a sensor
• CPC Class Codes: F16H 2312/022 Preparing to drive off
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/28 with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted
• CPC Class Codes: F16H 61/682 with interruption of drive
• CPC Class Codes: Y10T 74/19251 Control mechanism

Abstract

A gear-shift mechanism for a gear transmission in which a shift-and-select lever on a changeover shaft is loaded by a compression spring assembled therewith toward an initial position where the shift-and-select lever is brought into engagement with a shift head for 1^st-2^nd speeds for selectively establishing first or second speed gear train, and in which in the occurrence of a failure in any one of a selection-stroke sensor and a shift-stroke sensor, a second actuator is deactivated under control of an electric controller to permit free movement of the changeover shaft in an axial direction and a second actuator is activated under control of the electric controller to effect rotary movement of the changeover shaft so that the shift-and-select lever is moved to the initial position under the load of the compression spring and brought into engagement with the shift head to establish first or second speed gear train.

Claims

1. A gear-shift mechanism for a gear transmission including a changeover shaft mounted within a housing of the gear transmission for both axial and rotary movements to be axially shifted from a neutral position to a forward or reverse position in selecting operation and to be rotated at its shifted position in shifting operation, a shift-and-select lever fixed to an intermediate portion of the changeover shaft for axial and rotary movements therewith, an interlock member rotatably mounted in place on the changeover shaft and having a pair of interlock arms located at the opposite sides of the shift-and-select lever, detent means for restricting rotary movement of the interlock member and for permitting axial movement of the interlock member, a plurality of fork shafts mounted in parallel within the housing for axial movement in a shift direction perpendicular to the changeover shaft;

a plurality of shift forks mounted on the fork shafts to be selectively engaged with each sleeve of a plurality of changeover mechanisms for selectively establishing a plurality of change-speed gear trains in the gear transmission, a plurality of shift heads mounted on the fork shafts to be selectively engaged with the shift-and-select lever at their neutral positions, a first actuator operatively connected to the changeover shaft for effecting rotary movement of the changeover shaft when activated under control of an electric controller, a shift-stroke sensor for detecting the operation of the first actuator, a second actuator operatively connected to the changeover shaft for effecting axial movement of the changeover shaft when activated under control of the electric controller, and a selection-stroke sensor for detecting the operation of the second actuator,

wherein said shift-and-select lever is loaded by resilient means assembled therewith toward an initial position in which said shift-and-select lever is brought into engagement with one of said shift heads for establishing a low speed gear train, and wherein in the occurrence of a failure in at least one of said selection-stroke sensor and said shift-stroke sensor, said second actuator is deactivated under control of said electric controller to permit free movement of said changeover shaft in an axial direction and said first actuator is activated under control of said electric controller to effect rotary movement of said changeover shaft so that said shift-and-select lever is moved to the initial position under the load of said resilient means and brought into engagement with the one of said shift heads to establish the low speed gear train.

2. A gear-shift mechanism as claimed in claim 1, wherein a position switch is provided to detect a shifted position of at least one of said fork shafts by engagement therewith for detecting a failure in any one of said stroke sensors in relation to the detected position.

4. A gear-shift mechanism as claimed in claim 1, wherein a plurality of position switches are provided to detect a shifted position of each of said fork shafts by engagement therewith for detecting a failure in any one of said stroke sensors in relation to the detected position.

3. A gear-shift mechanism for a gear transmission including a changeover shaft mounted with a housing of the gear transmission for both axial and rotary movements to be axially shifted from a neutral position to a forward or reverse position in selecting operation and to be rotated at its shifted position in shifting operation, a shift-and-select lever fixed to an intermediate portion of the changeover shaft for axial and rotary movements therewith, an interlock member rotatably mounted in place on the changeover shaft and having a pair of interlock arms located at the opposite sides of the shift-and-select lever, detent means for restricting rotary movement of the interlock member and for permitting axial movement of the interlock member, a plurality of fork shafts mounted in parallel within the housing for axial movement in a shift direction perpendicular to the changeover shaft, shift forks for 1^st-2^nd speeds, 3^rd-4^th speeds and 5^th-6^th speeds mounted on the fork shafts to be selectively engaged with each sleeve of a plurality of changeover mechanisms for selectively establishing first to sixth speed gear trains in the gear transmission, shift heads for 1^st-2^nd speeds, 3^rd-4^th speeds and 5^th-6^th speeds mounted on the fork shafts to be selectively engaged with the shift-and-select lever at their neutral positions, a first actuator operatively connected to the changeover shaft for effecting rotary movement of the changeover shaft when activated under control of an electric controller, a shift-stroke sensor for detecting the operation of the first actuator, a second actuator operatively connected to the changeover shaft for effecting axial movement of the changeover shaft when activated under control of the electric controller, and a selection-stroke sensor for detecting the operation of the second actuator,

wherein said shift-and-select lever is loaded by resilient means assembled therewith toward an initial position in which said shift-and-select lever is brought into engagement with said shift head for 1^st-2^nd speeds for selectively establishing first and second speed gear trains, and wherein in the occurrence of a failure in at least one of said selection-stroke sensor and said shift-stroke sensor, said second actuator is deactivated under control of said electric controller to permit free movement of said changeover shaft in an axial direction and said first actuator is activated under control of said electric controller to effect rotary movement of said changeover shaft so that said shift-and-select lever is moved to the initial position under the load of said resilient means and brought into engagement with said shift head for 1^st-2^nd speeds to establish the first or second speed gear train.