Speed control structure and method for work vehicle

• US 20070137338A1
• Filed: 09/07/2006
• Published: 06/21/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Kubota Corporation
• Original Assignee: Kubota Corporation
• Inventors: Nishi, Eiji, Shinkai, Atsushi, Nishi, Keishiro, Nakatani, Yasunobu
• Granted Patent: US 7,613,560 B2
• Time in Patent Office: Days
• US Class Current: 74/335
• CPC Class Codes: F16H 2059/065 Inching pedals for setting the ratio of an hydrostatic transmission
• CPC Class Codes: F16H 2059/6853 the state of the transmission units, i.e. motor or pump capacity, e.g. for controlled shifting of range gear
• CPC Class Codes: F16H 47/02 the fluid gearing being of the volumetric type
• CPC Class Codes: F16H 59/42 Input shaft speed
• CPC Class Codes: F16H 61/423 Motor capacity control by fluid pressure control means
• CPC Class Codes: F16H 61/433 Pump capacity control by fluid pressure control means
• CPC Class Codes: F16H 61/46 Automatic regulation in accordance with output requirements
• CPC Class Codes: F16H 61/462 for achieving a target speed ratio
• CPC Class Codes: Y10T 74/19251 Control mechanism
• CPC Class Codes: Y10T 74/20037 Occupant propelled vehicle

Abstract

A speed control structure for a work vehicle comprises: a speed change operating element for manipulation by an operator; a device for detecting operated position of the speed change operating element; a continuously variable speed change device that receives power from an engine of the work vehicle; speed change position detecting device for detecting a speed change operation position of the continuously variable speed change device; operating device for speed-shifting the continuously variable speed change device; control device for controlling the operating means, wherein the control means: sets a target speed change operating position based on detected information by the operated position detection device and a predetermined correlation data that correlates the operated position of the speed change operating element and the speed change operation position of the continuously variable speed change device, and calculates a deviation between the target seed change operating position and of the continuously variable speed change device and the actual speed change operation position based on the set target seed change operating position and detected information from the speed change position detecting device, and sets a target operating speed for the continuously variable speed change device based on the calculated deviation and a further correlation data that correlates the deviation with an operating speed at which the continuously variable speed change device is operated, and controls the operating means such that the continuously variable speed change device is operated toward the target speed change operating position and at the target operating speed.

Claims

1. A speed control structure for a work vehicle comprising:

a speed change operating element for manipulation by an operator;

means for detecting operated position of the speed change operating element;

a continuously variable speed change device that receives power from an engine of the work vehicle;

speed change position detecting means for detecting a speed change operation position of the continuously variable speed change device;

operating means for speed-shifting the continuously variable speed change device;

control means for controlling the operating means, wherein the control means;

(a) sets a target speed change operating position based on detected information by the operated position detection means and a predetermined correlation data that correlates the operated position of the speed change operating element and the speed change operation position of the continuously variable speed change device, and

(b) calculates a deviation between the target seed change operating position and of the continuously variable speed change device and an actual speed change operation position based on the set target seed change operating position and detected information from the speed change position detecting means, and

(c) sets a target operating speed for the continuously variable speed change device based on the calculated deviation and a further correlation data that correlates the deviation with an operating speed at which the continuously variable speed change device is operated, and

(d) controls the operating means such that the continuously variable speed change device is operated toward the target speed change operating position and at the target operating speed.

2. A speed control structure according to claim 1, wherein

the control means is configured to be able to change the relationship between the deviation and the operating speed for the continuously variable speed change device based on an operation of an operator manipulated control.

3. A speed control structure according to claim 1, wherein

means for determining if the vehicle is traveling forward or in reverse is provided, and the control means is configured to be able to change the relationship between the deviation and the operating speed at which the continuously variable speed change device is operated, based on the detected information from the forward reverse determining means such that when the vehicle is in reverse, the operating speed at which the continuously variable speed change device is operated is slower than the speed when the vehicle is traveling forward.

4. A speed control structure according to claim 1, wherein

the operating means hydraulically operated and wherein the control structure includes an oil temperature sensor and wherein the control means is configured to be able to change the relationship between the deviation and the operating speed at which the continuously variable speed change device is operated, based on the detected information by the oil temperature sensor.

5. A speed control structure for a work vehicle comprising:

a speed change operating element configured to automatically return to a zero speed position;

means for detecting operated position of the speed change operating element;

constant speed operating element configured to be able to be maintained at any operated position;

means for detecting the maintained position of the constant speed operating element;

a continuously variable speed change device that receives power from an engine of the work vehicle;

speed change position detecting means for detecting a speed change operation position of a speed change operating member of the continuously variable speed change device;

operating means for operating the speed change operating member;

control means for controlling the operating means, wherein the control means sets a target speed change operating position based on detected information by the maintained position detecting means and detected information by the speed change position detecting means and based on correlation data that correlates the maintained position with the speed change operation position and

controls the operating means such that the speed change operating member is moved to the target speed change operating position.

6. A speed control structure according to claim 5, wherein

the control means sets a target operating speed based on correlation data that correlates a deviation between an actual speed change operation position detected by the speed change position detecting means and the target speed change operating position, with an operating speed at which the speed change control member, and controls the operating means such that the speed change control member is operated at the target operating speed.

7. A method for controlling a speed of a work vehicle, the work vehicle having a speed change operating element for manipulation by an operator, means for detecting operated position of the speed change operating element, a continuously variable speed change device that receives power from an engine of the work vehicle;

speed change position detecting means for detecting a speed change operation position of the continuously variable speed change device;

operating means for speed-shifting the continuously variable speed change device;

control means for controlling the operating means, the method comprising the steps of;

setting a target speed change operating position based on detected information by the operated position detection means and a predetermined correlation data that correlates the operated position of the speed change operating element and the speed change operation position of the continuously variable speed change device;

calculating a deviation between the target seed change operating position and of the continuously variable speed change device and an actual speed change operation position based on the set target seed change operating position and detected information from the speed change position detecting means;

setting a target operating speed for the continuously variable speed change device based on the calculated deviation and a further correlation data that correlates the deviation with an operating speed at which the continuously variable speed change device is operated; and

controlling the operating means such that the continuously variable speed change device is operated toward the target speed change operating position and at the target operating speed.

8. A method according to claim 7 further comprising:

changing the relationship between the deviation and the operating speed for the continuously variable speed change device based on an operation of an operator manipulated control.

9. A method according to claim 7, wherein

the work vehicle has means for determining if the vehicle is traveling forward or in reverse, and

wherein the method includes changing the relationship between the deviation and the operating speed at which the continuously variable speed change device is operated, based on the detected information from the forward reverse determining means such that when the vehicle is in reverse, the operating speed at which the continuously variable speed change device is operated is slower than the speed when the vehicle is traveling forward.

10. A method according to claim 7, wherein

the operating means operates hydraulically, and the work vehicle has a temperature sensor for detecting a temperature of the hydraulic fluid, and

the method includes changing the relationship between the deviation and the operating speed for the continuously variable speed change device based on detected information from the temperature sensor.

11. A method for controlling a speed of a work vehicle, the work vehicle having a speed change operating element that configured to automatically return to a zero speed position;

means for detecting operated position of the speed change operating element;

constant speed operating element configured to be able to be maintained at any operated position;

means for detecting maintained position of the constant speed operating element;

a continuously variable speed change device that receives power from an engine of the work vehicle;

speed change position detecting means for detecting a speed change operation position of a speed change operating member of the continuously variable speed change device;

operating means for operating the speed change operating member;

control means for controlling the operating means, the method comprising the steps of;

setting a target speed change operating position based on detected information by the maintained position detecting means and detected information by the speed change position detecting means and based on correlation data that correlates the maintained position with the speed change operation position; and

controlling the operating means such that the speed change operating member is moved to the target speed change operating position.

12. A method according to claim 11, wherein

setting a target operating speed based on correlation data that correlates a deviation between an actual speed change operation position detected by the speed change position detecting means and the target speed change operating position, with an operating speed at which the speed change control member is operated;

and

controlling the operating means such that the speed change operating member is operated at the target operating speed.