Apparatus and method for limiting vehicle speed of a working vehicle

An apparatus suitable for limiting a vehicle speed of a working vehicle, wherein the working vehicle includes:

• an accelerator pedal;
• a depressing stroke detector, for detecting a depressing stroke amount of said accelerator pedal;
• an engine control device, for outputting an accelerating signal based on the magnitude of a depressing stroke signal inputted from said depressing stroke detector;
• and
• an engine, a speed of which is controlled by said accelerating signal;
• said apparatus comprising:
• a vehicle speed detector, for detecting the vehicle speed of said working vehicle to output a vehicle speed signal;
• and
• a vehicle speed control device, connected to said depressing stroke detector, said vehicle speed detector, and said engine control device;
• wherein said vehicle speed control device:
• inputs said vehicle speed signal and said depressing stroke signal to compare a predetermined vehicle speed threshold value, which is smaller than a vehicle speed limit value, with said vehicle speed signal,
• judges a vehicle speed limit traveling period, when said vehicle speed signal is equal to or greater than said predetermined vehicle speed threshold value, to calculate a corrected depressing stroke signal, by a control gain which obtains a correction amount of said depressing stroke signal based on acceleration calculated from said vehicle speed signal and a deviation value between said vehicle speed signal and said predetermined vehicle speed limit value so that said deviation value becomes smaller, and to output said corrected depressing stroke signal to said engine control device, and
• judges an accelerated traveling period, when said vehicle speed signal is smaller than said predetermined vehicle speed threshold value, to output said depressing stroke signal to said engine control device.

An apparatus suitable for limiting a vehicle speed of a working vehicle, wherein the working vehicle includes:

• an accelerator pedal;
• an accelerator lever, operated based on a depressing stroke amount of said accelerator pedal;
• and
• an engine, a speed of which is controlled by said accelerator lever through a mechanical governor device;
• said apparatus comprising:
• a vehicle speed detector, for detecting a vehicle speed of the working vehicle;
• a vehicle speed control device, for inputting a vehicle speed signal from said vehicle speed detector, and having:
• a vehicle speed limit control means,
• an acceleration-deceleration/constant speed judging means, and
• a control gain changing means;
• a driving device, for inputting a command signal from said vehicle speed control device;
• and
• an actuator, driven by said driving device and correcting said depressing stroke amount to control said accelerator lever;
• wherein said vehicle speed limit control means:
• judges a vehicle speed limit traveling period, when said vehicle speed signal is equal to or greater than a predetermined vehicle speed limit value, to output to said driving device a command signal calculated by a control gain, based on a deviation value between said vehicle speed signal and said vehicle speed limit value or based on acceleration calculated by said vehicle speed signal and said deviation value, such that said deviation value becomes smaller, and
• judges an accelerated traveling period, when said vehicle speed signal is smaller than said predetermined vehicle speed limit value and the calculated command signal is smaller than a predetermined initial value, to output a command of said predetermined initial value to said driving device;
• wherein said acceleration-deceleration/constant speed judging means:
• judges a stable vehicle speed period, when said deviation value in said vehicle speed limit traveling period is less than or equal to a predetermined value over a predetermined period of time, and
• judges an acceleration-deceleration period, in a case other than said stable vehicle speed period, to output to said control gain changing means a result of a judgment by said acceleration-deceleration/constant speed judging means, and
• wherein said control gain changing means outputs to said vehicle speed limit control means, a control gain in said stable vehicle speed period or a control gain in said acceleration-deceleration period, in response to a result of a judgment by said acceleration-deceleration/constant speed judging means.

An apparatus suitable for limiting a vehicle speed of a working vehicle, wherein the working vehicle includes:

• an accelerator pedal;
• an accelerator lever, operated based on a depressing stroke amount of said accelerator pedal;
• and
• an engine, a speed of which is controlled by said accelerator lever through a mechanical governor device;
• said apparatus comprising:
• a vehicle speed detector, for detecting a vehicle speed of the working vehicle;
• a vehicle speed control device, in which a vehicle speed limit value and a predetermined vehicle speed threshold value, which is smaller than said vehicle speed limit value, are set in advance, to which a vehicle speed signal is inputted from said vehicle speed detector, and which has:
• a vehicle speed limit control means,
• an acceleration-deceleration/constant speed judging means, and
• a control gain changing means;
• a driving device, for inputting a command from said vehicle speed control device;
• and
• an actuator, driven by said driving device, for correcting said depressing stroke amount to control said accelerator lever;
• wherein said vehicle speed limit control means:
• judges a vehicle speed limit traveling period, when said vehicle speed signal is equal to or greater than said predetermined vehicle speed threshold value, to output to said driving device a command calculated by a control gain, based on a deviation value between said vehicle speed signal and said predetermined vehicle speed limit value or based on acceleration calculated from said vehicle speed signal and said deviation value such that said deviation value becomes smaller, and
• judges an accelerated traveling period, when said vehicle speed signal is smaller than said vehicle speed threshold value, to output a command of a predetermined initial value to said driving device;
• wherein said acceleration-deceleration/constant speed judging means:
• judges a stable vehicle speed period, when said deviation value in said vehicle speed limit traveling period is less than or equal to a predetermined value over a predetermined period of time, and
• judges an acceleration-deceleration period, in a case other than said stable vehicle speed period, to output to said control gain changing means a results of a judgment by said acceleration-deceleration/constant speed judging means;
• and
• wherein said control gain changing means outputs to said vehicle speed limit control means a control gain in said stable vehicle speed period or a control gain in said acceleration-deceleration period in response to a result of a judgment by said acceleration-deceleration/constant speed judging means.

An apparatus suitable for limiting a vehicle speed of a working vehicle, wherein the working vehicle includes:

• an accelerator pedal;
• an accelerator lever, operated based on a depressing stroke amount of said accelerator pedal;
• and
• an engine, a speed of which is controlled by said accelerator lever through a mechanical governor device;
• said apparatus comprising:
• a vehicle speed detector, for detecting a vehicle speed of the working vehicle;
• a vehicle speed control device, for:
• inputting a vehicle speed signal from said vehicle speed detector, and
• judging a vehicle speed limit traveling period, when said vehicle speed signal is equal to or greater than a predetermined vehicle speed limit value, to output to said driving device a command calculated such that a deviation between said vehicle speed signal and said predetermined vehicle speed limit value becomes smaller;
• a driving device, for inputting a command from said vehicle speed control device;
• an actuator, driven by said driving device, for correcting said depressing stroke amount to control said accelerator lever;
• a first shaft, having said accelerator pedal adhered to an outer periphery thereof;
• a first member, of which a first end is adhered to said first shaft, and which rotates about a first central axis of said first shaft in proportion to said depressing stroke amount;
• and
• a second shaft, through which a second end of said first member is passed in a direction of a second central axis, which is parallel to said first central axis, and which freely rotates about said second central axis while being supported by said first member;
• wherein said actuator rotates said second shaft about said second central axis;
• and
• wherein said second shaft is rotated by at least one of said actuator and said accelerator pedal to actuate said accelerator lever.

A method of limiting a vehicle speed of a working vehicle to be equal to or lower than a vehicle speed limit value, based on a depressing stroke amount of an accelerator pedal and the vehicle speed, said method comprising:

• judging a vehicle speed limit traveling period, when said vehicle speed is equal to or greater than said vehicle speed limit value, to calculate a corrected depressing stroke amount based on a deviation value between said vehicle speed and said vehicle speed limit value so that said deviation value becomes smaller, to control said vehicle speed by said corrected depressing stroke amount;
• judging an accelerated traveling period, when said vehicle speed is lower than said vehicle speed limit value and said corrected depressing stroke amount is larger than said depressing stroke amount, to control said vehicle speed by said depressing stroke amount;
• judging a stable vehicle speed period, when said deviation value in said vehicle speed limit traveling period is less than or equal to a predetermined value over a predetermined period of time;
• and
• judging an acceleration-deceleration period, in a case other than said stable vehicle speed period, to control said vehicle speed by a corrected depressing stroke amount calculated, based on different control gains in said stable vehicle speed period or in said acceleration-deceleration period, and said deviation value so that said deviation value becomes smaller.

A method of limiting a vehicle speed of a working vehicle to be less than or equal to a vehicle speed limit value, based on a depressing stroke amount of an accelerator pedal and the vehicle speed, said method comprising:

• setting in advance a predetermined vehicle speed threshold value, which is smaller than said vehicle speed limit value;
• judging a vehicle speed limit traveling period, when said vehicle speed is equal to or greater than said vehicle speed threshold value, to calculate a corrected depressing stroke amount based on acceleration calculated from said vehicle speed and a deviation value between said vehicle speed and said vehicle speed limit value so that said deviation becomes smaller, and to control said vehicle speed by said corrected depressing stroke amount;
• and
• judging an accelerated traveling period, when said vehicle speed is lower than said vehicle speed threshold value, to control said vehicle speed by said depressing stroke amount.