Gear ratio shift control system for automatic vehicle transmission

• US 5,964,675 A
• Filed: 08/26/1998
• Issued: 10/12/1999
• Est. Priority Date: 08/29/1997
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Shimada, Takamichi, Sekine, Noboru
• Primary Examiner(s): Wright, Dirk
• Assistant Examiner(s): KWON, TAI CHOON
• Application Number:
  US09/140,283
• Time in Patent Office: 412 Days
• Field of Search: 477/176, 477/174, 477/175, 477/86, 477/143, 477/156, 701/67, 701/66, 475/116, 475/120, 475/121, 475/123, 475/128, 74/335, 74/336 R
• US Class Current: 475/123
• CPC Class Codes: F16H 2061/0087 Adaptive control, e.g. the control parameters adapted by learning
• CPC Class Codes: F16H 2061/0462 by controlling slip rate during gear shift transition
• CPC Class Codes: F16H 2200/201 with three sets of orbital gears
• CPC Class Codes: F16H 2200/2097 comprising an orbital gear set member permanently connected to the housing, e.g. a sun wheel permanently connected to the housing
• CPC Class Codes: F16H 3/666 with compound planetary gear units, e.g. two intermeshing orbital gears F16H3/663 takes precedence
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/686 with orbital gears

Abstract

A system for controlling gear (gear ratio) shifting in an automatic transmission mounted on a vehicle, including a shift control means for generating a shift command to upshift from one gear (gear ratio) currently established to a next gear (gear ratio) by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear (gear ratio) so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear (gear ratio) to be shifted to. The system includes a first step for determining the command such that an actual slip rate of the frictional engaging elements that establish the current gear (gear ratio) converges to a first desired slip rate, a second step for determining the command such that the actual slip rate of the frictional engaging elements that establish the current gear (gear ratio) converges to a second desired slip rate, maximum slip rate detecting means for detecting a maximum actual slip rate, slip rate difference calculating means for calculating a difference between the detected maximum actual slip rate and the second desired slip rate, command correcting means for correcting the command in response to the calculated difference, and command storing means for storing the corrected command to be used as the command in the first step in controlling a next upshift. This arrangement can avoid the clutches (and brakes) from being suffered excessive slippage, thereby improving the service life of the clutches and brakes and making the control to smooth shift to that for the next gear (gear ratio).

Claims

1. A system for controlling gear ratio shifting in an automatic transmission mounted on a vehicle, including:

a plurality of gear trains which transmit engine torque to a drive shaft;

a plurality of frictional engaging elements which operate to selectively establish one gear ratio from among the gear ratios;

shift solenoid valves provided in an oil pressure control circuit connected to a source of pressurized oil; and

shift control means for generating a shift command to upshift from one gear ratio currently established to a next gear ratio by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear ratio so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear ratio to be shifted to;

wherein;

said shift control means comprises;

a first step for determining the command such that an actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a first desired slip rate;

a second step for determining the command such that the actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a second desired slip rate;

maximum slip rate detecting means for detecting a maximum actual slip rate;

slip rate difference calculating means for calculating a difference between the detected maximum actual slip rate and the second desired slip rate;

command correcting means for correcting the command in response to the calculated difference; and

command storing means for storing the corrected command to be used as the command in the first step in controlling a next upshift.

2. A system according to claim 1, wherein the command in the second step is larger than that in the first step.

3. A system according to claim 1, where said second desired slip rate determining means determines the second desired slip rate by calculating an average value of the detected maximum slip rate and the first desired slip rate.

4. A system according to claim 2, where said second desired slip rate determining means determines the second desired slip rate by calculating an average value of the detected maximum slip rate and the first desired slip rate.

5. A method of controlling gear ratio shifting in an automatic transmission mounted on a vehicle, including:

a plurality of gears each of which transmit engine torque to a drive shaft;

a plurality of frictional engaging elements which operate to selectively establish one gear ratio from among the gear ratios; and

shift solenoid valves provided in an oil pressure control circuit connected to a source of pressurized oil;

and including the step of;

generating a shift command to upshift from one gear ratio currently established to a next gear ratio by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear ratio so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear ratio to be shifted to;

wherein the method comprises the steps of;

determining the command such that an actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a first desired slip rate;

determining the command such that the actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a second desired slip rate;

detecting means for detecting a maximum actual slip rate;

calculating a difference between the detected maximum actual slip rate and the second desired slip rate;

correcting the command in response to the calculated difference ; and

storing the corrected command to be used as the command in the first step in controlling a next upshift.

6. A method according to claim 5, wherein the command in the second step is larger than that in the first step.

7. A method according to claim 5, where said second desired slip rate is determined by calculating an average value of the detected maximum slip rate and the first desired slip rate.

8. A method according to claim 6, where said second desired slip rate is determined by calculating an average value of the detected maximum slip rate and the first desired slip rate.

9. A computer program embodied on a computer-readable medium for controlling gear ratio shifting in an automatic transmission mounted on a vehicle, including:

a plurality of gear trains each of which transmits engine torque to a drive shaft;

a plurality of frictional engaging elements which operate to selectively establish one gear ratio from among the gear ratios; and

shift solenoid valves provided in an oil pressure control circuit connected to a source of pressurized oil;

and including the step of;

generating a shift command to upshift from one gear ratio currently established to a next gear ratio by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear ratio so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear ratio to be shifted to;

wherein the method comprises the steps of;

determining the command such that an actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a first desired slip rate;

determining the command such that the actual slip rate of the frictional engaging elements that establish the current gear ratio converges to a second desired slip rate;

detecting means for detecting a maximum actual slip rate;

calculating a difference between the detected maximum actual slip rate and the second desired slip rate;

correcting the command in response to the calculated difference; and

storing the corrected command to be used as the command in the first step in controlling a next upshift.