Method of automatically changing the speed stage of a vehicle based on vehicle loading

• US 5,319,559 A
• Filed: 03/30/1993
• Issued: 06/07/1994
• Est. Priority Date: 02/04/1987
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Original Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Inventors: Kusaka, Kohei, Kato, Yoshiaki, Kato, Takeo, Kaneko, Kiyoshi
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US08/040,378
• Time in Patent Office: 434 Days
• Field of Search: 364/424.1, 364/426.01, 364/426.04, 364/442, 364/431.01, 364/431.07, 74/866, 74/856, 74/860, 74/861, 123/352, 123/357, 123/358, 123/478, 180/306, 180/338
• US Class Current: 701/110
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 2530/16 Driving resistance
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: B60Y 2200/14 Trucks; Load vehicles, Busses
• CPC Class Codes: F16H 2059/743 using engine performance or power for control of gearing transmission input torque F16H2059/147
• CPC Class Codes: F16H 2061/0012 Transmission control for optimising power output of driveline
• CPC Class Codes: F16H 2061/0015 Transmission control for optimising fuel consumptions
• CPC Class Codes: F16H 2061/0209 with independent solenoid valves modulating the pressure individually for each clutch or brake
• CPC Class Codes: F16H 2061/026 On-off solenoid valve
• CPC Class Codes: F16H 2302/04 Determining a modus for shifting selection of shift speed modus F16H2059/0226
• CPC Class Codes: F16H 2306/44 Removing torque from current gears
• CPC Class Codes: F16H 2306/54 Synchronizing engine speed to transmission input speed
• CPC Class Codes: F16H 59/14 Inputs being a function of torque or torque demand
• CPC Class Codes: F16H 59/18 dependent on the position of the accelerator pedal
• CPC Class Codes: F16H 59/48 Inputs being a function of acceleration
• CPC Class Codes: F16H 59/52 dependent on the weight of the machine, e.g. change in weight resulting from passengers boarding a bus
• CPC Class Codes: F16H 59/54 : dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 61/0021 : Generation or control of line pressure
• CPC Class Codes: F16H 61/0213 : characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/0437 : by using electrical signals F16H61/0403 and F16H61/061 take precedence
• CPC Class Codes: F16H 61/061 : using electric control means
• CPC Class Codes: F16H 61/14 : Control of torque converter lock-up clutches
• CPC Class Codes: F16H 61/143 : using electric control means
• CPC Class Codes: F16H 61/68 : specially adapted for stepped gearings
• CPC Class Codes: F16H 61/686 : with orbital gears
• CPC Class Codes: F16H 61/70 : specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements
• CPC Class Codes: F16H 63/502 : for smoothing gear shifts
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration

Abstract

A method for automatically changing the speed of a dump truck for use as a construction vehicle which is capable of improving the fuel cost by utilizing the engine output effectively and efficiently, improving the durability of the power transmission system and giving the driver a comfortable ride. According to this automatic speed change method, a desired, optimum speed stage which meets the loading condition of the dump truck and/or the engine output condition can be selected by using controllers each having a built-in computer.

Claims

1. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

establishing engagement of said lock-up clutch for direct transmission of engine output to said power transmission while said vehicle is in a normal running condition;

disengaging said lock-up clutch in response to a shifting down signal issued from said controller for transmission of the engine output through said torque converter;

commanding for temporarily increasing an engine speed in a given magnitude for a given period and responsive to completion of a shifting down operation of the transmission speed ratio in order to minimize a difference between an engine speed and an input speed downstream of the torque converter for said power transmission; and

re-establishing a lock-up condition while the engine speed is held at the temporarily increased speed so that said lock-up condition of said torque converter is established while said speed difference is minimized.

2. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

detecting an engine speed;

discriminating a weight load condition on said construction vehicle between a heavy weight load condition and a light weight load condition; and

differentiating shifting points of the transmission speed ratio in such a manner that when the discriminated weight load condition is the heavy weight load condition, the shifting point is set at an engine speed generating a maximum output and when the discriminated weight load condition is the light weight load condition, the shift point is set at an engine speed lower than said engine speed generating the maximum output.

3. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

detecting an engine speed;

discriminating a weight load condition on said construction vehicle between a heavy weight load condition and a light weight load condition; and

differentiating shifting points of the transmission speed ratio in such a manner that when the discriminated weight load condition is the heavy weight load condition, the shifting point is set at an engine speed generating a maximum output and when the discriminated weight load condition is the light weight load condition, the shifting point is set at an engine speed lower than said engine speed generating the maximum output;

driving the construction vehicle at a constant speed under said light weight load condition when a marginal engine output is sufficient so as not to cause hunting,

inputting the position of a means for controlling the amount of fuel injected into the engine and the engine speed developed by the engine when the construction vehicle is running at the constant speed to said controller for computing the end-developed output and then computing the engine speed at a point of intersection of the equi-horsepower curve and an engine characteristics curve corresponding to that developed by the engine at its maximum output condition; and

comparing the product of the computed engine speed and the speed reduction ratio at a corresponding next higher speed stage with the product of the current engine speed and speed reduction ratio at a current speed stage if the former product is larger than the latter product, outputting a shift-up signal to said controller so that a speed stage is selected which is higher than that which would be selected by said automatic speed change in the event that vehicle was running in the heavy load condition.

4. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

providing a running mode change over switch operable for selecting a plurality of predetermined running modes;

adjusting fuel delivery amount to the engine corresponding to the selected running mode for adjusting maximum output of the engine between a higher level and a lower level;

setting the maximum output of the engine at said higher level by switching said running mode change over switch and setting the shifting point of said power transmission for each speed ratio at the engine speed corresponding to the higher level of the engine maximum output while the weight load on the vehicle is heavy; and

setting the maximum output of the engine at said lower level by switching said running mode change over switch and setting the shifting point of said power transmission for each speed ratio at the engine speed corresponding to the lower level of the maximum engine output and lower than that set under the heavy weight load condition while the weight load on the vehicle is light.

5. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

detecting input speed of said power transmission;

detecting abrupt deceleration of said vehicle from a running condition at a high speed;

detecting accelerator position for generating a first signal indicative thereof;

detecting an input speed of said power transmission for generating a second signal indicative thereof;

detecting a current speed ratio of the power transmission for generating a third signal indicative thereof;

deriving a vehicular deceleration on the basis of said input speed of the power transmission at the high speed and the current input speed;

selecting one of said speed ratios which are preliminarily set in terms of said high speed and said vehicular deceleration, on the basis of the derived vehicular deceleration; and

outputting the selected speed ratio to said controller when a vehicular speed reaches a speed corresponding to the selected speed ratio for performing shifting to the selected speed ratio at one shifting operation.

6. A method for automatically shifting speed ratios of an automatic power transmission for a construction vehicle, in which the output side of an engine is connected to a torque converter incorporating a lock-up clutch, the output side of said torque converter is connected to the input side of a hydraulically actuated power transmission having a plurality of clutches for a plurality of mutually distinct speed ratios, and the output side of the power transmission is connected through a differential gear mechanism to drive wheels, and a computer-based transmission controller for selectively establishing an optimum speed ratio on the basis of predetermined control parameters,

the method comprising the steps of:

generating a weight load signal representative of a weight of a load to be carried by the vehicle; and

adjusting a line pressure of the working fluid to be supplied to said hydraulically actuated power transmission in such a manner that the clutch of the selected speed ratio is swiftly engaged for establishing the selected speed ratio with a high response while the weight represented by said weight load signal is heavy and the clutch of the selected speed ratio is moderately engaged for establishing the selected speed ratio with minimized shift shock.