Change-speed control system for utility vehicle having stepless change-speed apparatus for speed-changing engine output and transmitting the speed-changed output to traveling unit

• US 6,887,182 B2
• Filed: 08/29/2003
• Issued: 05/03/2005
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Kubota Corporation
• Original Assignee: Kubota Corporation
• Inventors: Horiuchi, Yoshifumi, Nakatani, Yasunobu
• Primary Examiner(s): LEWIS, TISHA D
• Application Number:
  US10/652,581
• Publication Number:
  US 20050037892A1
• Time in Patent Office: 613 Days
• Field of Search: 477/120, 477/902, 477/904, 180/364, 180/368, 180/900
• US Class Current: 477/120
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/103 of fluid type
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/18063 Creeping
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 57/04 Features relating to lubrication or cooling or heatingin hydrokinetic gearing F16H41/30; control of lubrication or cooling in hydrostatic gearing F16H61/4165
• CPC Class Codes: Y10S 180/90 Argicultural-type tractors
• CPC Class Codes: Y10T 74/19149 with fluid drive
• CPC Class Codes: Y10T 74/2186 Gear casings

Abstract

A change-speed control system is provided for a utility vehicle having a stepless change-speed apparatus for speed-changing an engine output and transmitting the speed-changed output to a traveling unit. The system includes an engine speed governor for adjusting speed of the engine, an accelerator controller and a change-speed control linkage device for providing operative displacements in the stepless change-speed apparatus and the engine speed governor in association with an operation of the accelerator controller. The change-speed control linkage device sets an operation amount for the stepless change-speed apparatus and an operation amount for the engine speed governor in correlation with the operation amount of the accelerator controller, such that an acceleration ratio for the engine speed is greater than an acceleration ratio for the stepless change-speed apparatus until the engine reaches a predetermined speed and also the stepless change-speed apparatus reaches a predetermined speed.

Claims

1. A change-speed control system for a utility vehicle having a stepless change-speed apparatus for speed-changing an engine output and transmitting the speed-changed output to a traveling unit, comprising:

an engine speed governor for adjusting speed of the engine;

an accelerator controller; and

a change-speed control linkage device for providing operative displacements in the stepless change-speed apparatus and the engine speed governor in association with an operation of the accelerator controller;

wherein said change-speed control linkage device sets an operation amount for the stepless change-speed apparatus and an operation amount for the engine speed governor in correlation with the operation amount of the accelerator controller, such that an acceleration ratio for the engine speed is greater than an acceleration ratio for the stepless change-speed apparatus until the engine reaches a predetermined speed and also the stepless change-speed apparatus reaches a predetermined speed.

2. The change-speed control system according to claim 1, wherein the change-speed control linkage device comprises a pivot link mechanism for dividing an operational displacement of the accelerator controller by a predetermined ratio between an operational displacement of the stepless change-speed apparatus and an operational displacement of the engine speed governor.

3. The change-speed control system according to claim 2, wherein the pivot link mechanism includes a pivot link member operatively connected with the accelerator controller, a governor side link member slidable by said pivot link member for operating an operational portion of the engine speed governor, and a change-speed apparatus side link member slidable by said pivot link member for operating an operational portion of the stepless change-speed apparatus.

4. The change-speed control system according to claim 3, wherein the governor side link member and the change-speed apparatus side link member are operably connected with the pivotal link member as a pivot link such that with increase in the engine speed, an operational efficiency of the governor side link member by the pivot link member may be reduced and at the same time an operational efficiency of the change-speed apparatus side link member by the pivot link member may be increased.