Dipl.Ing.（FH）Christoph Göbel ZF Friedrichshafen AG－Operations and Technology ZF Group

1 前言

多年来，无级变速器已成功进入市场。但是多档变速器（通常在部分载荷下换档）仍然是拖拉机的标准传动方式。这就是为什么会产生将无级变速器（功能更多、操作更便捷、更舒适、自动控制等）所具有的功能扩展到多档变速器中。

这里部分挑战来自定义批量生产准备阶段的功能和通过机械、液压和电子（硬件和软件）加以实现。不断增加的控制单元、界面、（某些时候与CAN网络的联接）功能需要更具创新性的开发过程，特别是涉及软件时。

本文通过实例叙述拖拉机用多档变速器功能的扩展和说明必要的软件开发过程基本原理。

1 Introduction

For some years now，continuously variable transmissions are introduced successfully on the market.Nevertheless，multistep transmissions（usually shiftable under partial load）remain the standard drive solution for tractors.This is why ideas from continuously variable transmissions（additional functions，easier operation with increased comfort，automation，etc.）are also applied to multistep transmissions more and more.

A particular challenge here is to specify volume－production－ready functions and implement them in mechanics，hydraulics，and electronics（both hardware and software）.The growing number of control units，interfaces，and（in some cases interlinked on e.g.CAN network）functions require more innovative development processes，especially when it comes to software.

This article uses examples to describe expanded functions of multistep transmissions for tractors，and explains basic principles of the necessary software development processes.

2 T7000拖拉机传动装置、系统详细资料

带动力换档的拖拉机具有很多种用于控制各项功能的操作机构和显示元件。考虑到当今复杂拖拉机所具有的范围广泛的行驶、作业和操作功能（图1），控制系统的人机工程设计就成为一个重要因素。目前在技术方面的创新关注于这些需求并至少向以下目标之一前进：

·通过自动控制的典型程序提高驾驶舒适性

·利用人机工程设计的控制和显示设备改善操作舒适性

·提高换档品质

·通过提高最高行驶速度扩展拖拉机使用范围

·缩短响应时间以优化作业过程

·减少反作用力以提高使用寿命

以下将通过大量实例论述在不影响安全性和可靠性的前提下这些目标是如何实现的。

2 T7000Tractor Transmission，System Details

Tractors with powershift transmissions feature a large number of operating and display elements for control of the various functions.Considering the extensive range of driving，working，and operating functions of today＇s complex tractors（Figureergonomic design of the control system is a major factor.Today＇s technological innovations address these needs and pursue at least one of the following goals：

·Increasing driving comfort through automation of typical processes

·Increasing operating comfort with ergonomic design of the controls and displays

·Improving shifting comfort

·Expanding the scope of the tractor by increasing the maximum driving speed

·Optimizing working processes through shorter reaction times

·Increasing service life with smaller reaction forces

In the following，various examples are used to illustrate how these goals are achieved without compromising on safety and reliability.

图1 T7000变速器控制系统简图Fig.1 System control schema of atypical T7000transmission application

3 增加舒适性、自动操作和安全性方面的功能

3.1 自动耕地/道路切换（FRRS）

ZF公司T7000变速器可作为一个频繁切换过程自动操作的良好实例。……