Motor Control Device for Working Vehicle

• US 20120095655A1
• Filed: 06/17/2010
• Published: 04/19/2012
• Est. Priority Date: 06/19/2009
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Hyodo, Koji, Nakazono, Hiroki, Yoshikawa, Masaki, Aoki, Tadayoshi, Aoki, Isamu
• Granted Patent: US 8,655,557 B2
• Time in Patent Office: Days
• US Class Current: 701/50
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 30/184 Preventing damage resulting from overload or excessive wear of the driveline
• CPC Class Codes: E02F 9/2246 Control of prime movers, e.g. depending on the hydraulic load of work tools
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 2200/501 Vehicle speed
• CPC Class Codes: F02D 2200/602 Pedal position
• CPC Class Codes: F02D 2200/604 Engine control mode selected by driver, e.g. to manually start particle filter regeneration or to select driving style
• CPC Class Codes: F02D 2400/12 Engine control specially adapted for a transmission comprising a torque converter or for continuously variable transmissions
• CPC Class Codes: F02D 29/00 Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
• CPC Class Codes: F02D 31/001 Electric control of rotation speed
• CPC Class Codes: F02D 31/009 for maximum speed control
• CPC Class Codes: F02D 41/0205 using an auxiliary engine speed control engine speed control per se F02D31/00
• CPC Class Codes: F02D 41/0215 in relation with elements of the transmission
• CPC Class Codes: F02D 41/0225 in relation with the gear ratio or shift lever position
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F16H 2059/467 of torque converter
• CPC Class Codes: F16H 59/70 dependent on the ratio established

Abstract

A working vehicle motor control device includes: a rotational speed control device that controls a motor rotational speed in accordance with an operation amount of an accelerator pedal; a travel drive device that transmits rotation of the motor to wheels through a torque converter and a transmission; a speed ratio detection device that detects a speed ratio of an input shaft and an output shaft of the torque converter; and a speed restriction device that restricts a maximum rotational speed of the motor in accordance with a speed ratio detected by the speed ratio detection device. In the working vehicle motor control device, the speed restriction device restricts the maximum rotational speed when a detected speed ratio is in an acceleration region of the motor rotational speed to less than the maximum rotational speed when a detected speed ratio is in a non-acceleration region.

Claims

1. A motor control device for a working vehicle, comprising:

a rotational speed control device that controls a rotational speed of a motor in accordance with an operation amount of an accelerator pedal;

a travel drive device that transmits rotation of the motor to wheels through a torque converter and a transmission;

a speed ratio detection device that detects a speed ratio of an input shaft and an output shaft of the torque converter; and

a speed restriction device that restricts a maximum rotational speed of the motor in accordance with a speed ratio detected by the speed ratio detection device, wherein;

the speed restriction device restricts the maximum rotational speed when a detected speed ratio is in an acceleration region of the rotational speed of the motor to less than the maximum rotational speed when a detected speed ratio is in a non-acceleration region.

2. A motor control device for a working vehicle according to claim 1, wherein:

when a detected speed ratio becomes equal to or greater than a first predetermined value, the speed restriction device sets a restriction amount of the maximum rotational speed greater than that when a speed ratio is less than the first predetermined value.

3. A motor control device for a working vehicle according to claim 1, wherein:

the speed restriction device reduces a value of the maximum rotational speed when a detected speed ratio is equal to or greater than a first predetermined value and does not reduce a value of the maximum rotational speed when a speed ratio is less than the first predetermined value.

4. A motor control device for a working vehicle according to claim 2, wherein:

in a case where a speed step of the transmission is a low speed step of a first speed step or a second speed step, when a detected speed ratio is equal to or greater than the first predetermined value and less than a second predetermined value, which is greater than the first predetermined value, the speed restriction device, sets the restriction amount to be greater than that when a speed ratio is less than the first predetermined value and

equal to or greater than the second predetermined value.

5. A motor control device for a working vehicle according to claim 2, wherein:

the speed restriction device, after increasing the restriction amount, reduces the restriction amount as time passes.

6. A motor control device for a working vehicle according to claim 2, wherein:

in a case where a speed step of the transmission is a high speed step of equal to or greater than a third speed step, when a detected speed ratio is equal to or greater than the first predetermined value, the speed restriction device gradually increases the restriction amount with an increase in a speed ratio so that a maximum vehicle speed of a vehicle becomes a vehicle speed limit that is set in advance.

7. A motor control device for a working vehicle according to claim 6, further comprising:

a vehicle speed detection device that detects a vehicle speed, wherein;

when a vehicle speed detected by the vehicle speed detection device is equal to or greater than a set vehicle speed that is lower than the vehicle speed limit, the speed restriction device gradually increases the restriction amount, and, when a vehicle speed is less than the set vehicle speed, the speed restriction device does not restrict the maximum rotational speed.

8. A motor control device for a working vehicle according to claim 6, further comprising:

a determination device that makes a decision as to whether a value detected by the speed ratio detection device is normal or abnormal, wherein;

when the determination device makes a decision that the detection value is normal, the speed restriction device gradually reduces the maximum rotational speed to a predetermined value with an increase in a speed ratio, and, when the determination device makes a decision that the detection value is abnormal, the speed restriction device restricts the maximum rotational speed to the predetermined value regardless of a speed ratio.