Method and apparatus for controlling transmission system

• US 5,231,898 A
• Filed: 10/22/1992
• Issued: 08/03/1993
• Est. Priority Date: 11/24/1988
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Original Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Inventors: Okura, Yasunori
• Primary Examiner(s): Lorence, Richard M.
• Assistant Examiner(s): Levi, Benjamin
• Application Number:
  US07/965,622
• Time in Patent Office: 285 Days
• Field of Search: 74/866, 74/867, 192/0.044, 192/0.052, 192/0.075, 192/0.076
• US Class Current: 477/95
• CPC Class Codes: F16H 2059/6807 Status of gear-change operation, e.g. clutch fully engaged
• CPC Class Codes: F16H 2061/0096 using a parameter map
• CPC Class Codes: F16H 2061/0258 Proportional solenoid valve
• CPC Class Codes: F16H 59/18 dependent on the position of the accelerator pedal
• CPC Class Codes: F16H 59/54 dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 63/44 Signals to the control unit of auxiliary gearing

Abstract

In a configuration in which electronically operated pressure control valves (31-36) are respectively connected to clutches of a two-stage transmission (3) composed of main transmissions (1st, 2nd, R, 4th, 3rd) and sub transmissions (L, H), when a downshift is effected from a present speed stage to a next speed stage with power on, the supply of oil pressure to a speed-changing clutch for the present speed stage is stopped on the basis of a speed-change command, the pressure control valve is actuated when a relative number of revolutions of the speed-changing clutch for the next speed stage becomes zero, which commences the supply of oil pressure to that speed-changing clutch, and the supply of oil pressure is gradually increased upon confirming the completion of a filling time of the speed-changing clutch. Thus discomfort owing to a speed-change shock is prevented in whatever state the amount of an accelerator operated and the state of operation of a brake are.

In addition, in a downshift accompanying the operation of clutches of both transmissions, torque off time is not provided for the sub transmission clutch, and the supply of oil pressure to a next stage clutch is commenced immediately so as to supply oil pressure at a gradually increasing rate. After engagement of the clutch, the supply of oil pressure to the main transmission clutch at a gradually increasing rate is effected upon completion of the filling time, thereby preventing discomfort attributable to a speed-change shock.

Claims

1. A method of controlling a transmission system including an output shaft for receiving an output of an engine, an output shaft for outputting a drive force corresponding to said engine output to drive wheels, a plurality of speed-changing clutches provided for each of a plurality of speed stages and adapted to engage said input shaft and said output shaft at a time point when a pressure of supplied pressure oil exceeds a predetermined pressure so as to set a speed reduction rate corresponding to a speed stage selected by a speed-change command, and a plurality of pressure control valves respectively connected to said plurality of speed-changing clutches and adapted to supply pressure oil to one of said speed-changing clutches corresponding to said speed stage selected by said speed-change command during a filling time to fill out said one of said speed-changing clutches with the pressure oil and to gradually increase the pressure of the supplied oil after completion of the filling time so as to carry out said engagement, wherein said control valves are controlled when an output torque of said engine is more than a predetermined value and when a content of the speed-change command represents a shift down for selecting as a next speed stage a speed stage with a speed reduction rate greater than a presently selected speed stage, comprising the steps of:

a) turning off a first pressure control valve connected to a first speed-changing clutch corresponding to the presently selected speed stage upon the issuance of the speed-change command;

b) actuating a second pressure control valve connected to a second speed-changing clutch corresponding to said next speed stage at an operation start timing when a filling time of said second speed-changing clutch is completed, at a point of time when the relative number of revolutions of said second speed-changing clutch becomes zero, so as to supply pressure oil to said second speed-changing clutch; and

c) confirming the completion of said filling time of said second speed-changing clutch corresponding to said next speed stage, and subsequently controlling said second pressure control valve connected to said second speed-changing clutch in such a manner as to gradually increase the oil pressure of said second speed-changing clutch.

2. A method of controlling a transmission system including a sub transmission for reducing a revolutional speed of an input shaft for receiving an output of an engine to transmit a revolution of said input shaft to an intermediate shaft, a main transmission for reducing a revolutional speed of said intermediate shaft to transmit a revolution of said intermediate shaft to an output shaft connected to drive wheels, a plurality of sub transmission clutches provided in said sub transmission and adapted to engage said input shaft and said intermediate shaft at a time point when a pressure of supplied pressure oil exceeds a predetermined pressure so as to set a speed reduction rate of said sub transmission to be a speed reduction rate corresponding to a speed stage selected by a speed-change command, a plurality of main transmission clutches provided in said main transmission and adapted to engage said intermediate shaft and said output shaft at a time point when the pressure of the supplied pressure oil exceeds the predetermined pressure so as to set a speed reduction rate of said main transmission to be a speed reduction rate corresponding to the speed stage selected by said speed-change command, and a plurality of pressure control valves respectively connected to said sub transmission clutches and said main transmission clutches and adapted to supply the pressure oil to one of said sub transmission clutches and one of said main transmission clutches respectively corresponding to said speed stage selected by said speed-change command during respective filling times to fill out said ones of sub and main transmission clutches with the pressure oil and gradually increase the pressure of the supplied oil within said ones of sub and main transmission clutches after completion of the respective filling times so as to carry out said engagement, wherein said pressure control valves are controlled when an output torque of said engine is more than a predetermined value, when a content of said speed-change command represents a shift down for selecting as a next speed stage a speed stage in which a speed reduction rate from said input shaft to said output shaft becomes greater than the presently selected speed stage, and when a first sub transmission clutch and a first main transmission clutch corresponding to the presently selected speed stage respectively differ from a second sub transmission clutch and a second main transmission clutch corresponding to said next speed stage, comprising the steps of:

a) turning off a first pressure control valve connected to said first sub transmission clutch and said first main transmission clutch corresponding to said presently selected speed stage upon the issuance of said speed-change command;

b) starting the supply of pressure oil to said second sub transmission clutch corresponding to said next speed stage at a point of time when said first pressure control valve connected to said first sub transmission clutch corresponding to said presently selected speed stage is turned off, and subsequently controlling a second pressure control valve connected to said second sub transmission clutch in such a manner as to gradually increase the oil pressure of said second sub transmission clutch;

c) actuating said second pressure control valve connected to said second main transmission clutch corresponding to said next speed stage at an operation start timing when a filling time of said second main transmission clutch is completed, at a point of time when the relative number of revolutions of said second main transmission clutch becomes zero, so as to supply the pressure oil to said second main transmission clutch; and

d) confirming the completion of said filling time of said second main transmission clutch corresponding to said next speed stage, and subsequently controlling said second pressure control valve connected to said second main transmission clutch in such a manner as to gradually increase the oil pressure of said second main transmission clutch.

3. An apparatus for controlling a transmission system including an input shaft for receiving an output of an engine, an output shaft for outputting a drive force corresponding to the engine output to drive wheels, a plurality of speed-changing clutches provided for each of a plurality of speed stages and adapted to engage said input shaft and said output shaft at a time point when a pressure of supplied pressure oil exceeds a predetermined pressure so as to set a speed reduction rate corresponding to a speed stage selected by a speed-change command, and a plurality of pressure control valves respectively connected to said speed-changing clutches and adapted to supply pressure oil to one of said speed-changing clutches corresponding to said speed stage selected by said speed-change command during a filling time to fill out said one of said speed-changing clutches with the pressure oil and to change the oil pressure in response to an input electric command to gradually increase the oil pressure within said one of said speed changing clutches after completion of said filling time so as to carry out the engagement, said apparatus comprising;

first detecting means for detecting an a degree of actuation of an acceleration of a vehicle on which said transmission system is adapted to be mounted;

second detecting means for detecting a state of operation of a brake of such vehicle;

third detecting means for detecting a speed stage selected as a next speed stage by said speed-change command; and

controlling means for determining a rate of gradual increase of pressure of the pressure oil supplied to another one of said speed-changing clutches corresponding to said next speed stage in such a manner that;

if said second detecting means detects that said brake is not operating, said gradual increase rate increases as said degree of the actuation of the accelerator detected by said first detecting means increases;

if said second detecting means detects that said brake is operating, said gradual increase rate becomes a predetermined value regardless of the degree of the actuation of the accelerator detected by said first detecting means; and

the higher the next speed stage detected by said third detecting means is, the greater said gradual increase rate becomes; and

for outputting an electrical command corresponding to the determined gradual increase rate to one of said pressure control valves connected to said another one of said speed-changing clutches corresponding to said next speed stage.

4. An apparatus for controlling a transmission system according to claim 3, wherein said controlling means includes a memory for storing in advance a plurality of oil pressure gradual increase rates corresponding to the degree of the actuation of the accelerator, the state of operation of said brake, and said next speed stage, and generates said electric command outputted to said one of said pressure control valves connected to said another one of said speed-changing clutches corresponding to said next speed stage on the basis of data read from said memory.