s*******e
发帖数: 1298 | | i****x
发帖数: 17565 | 2 有意思
这有个设计图，谁能看明白道理。。我看起来，这就是个比较复杂的万向轴，一般万向
轴有两个垂直运动面，这玩意不知为啥有四个 | p*********e
发帖数: 32207 | 3 看了一下wiki的介绍
"
Thompson coupling[edit]
Thompson coupling from U.S. Patent 7,442,126. Note: drawing on the right
omits certain components in order to illustrate the control yoke's spherical
pantograph.
The Thompson constant velocity joint (TCVJ), also known as a Thompson
coupling, assembles two cardan joints within each other to eliminate the
intermediate shaft. A control yoke is added to keep the input and output
shafts aligned. The control yoke uses a spherical pantograph scissor
mechanism to bisect the angle between the input and output shafts and to
maintain the joints at a relative phase angle of zero. The alignment ensures
constant angular velocity at all joint angles. Eliminating the intermediate
shaft and keeping the input shafts aligned in the homokinetic plane greatly
reduces the induced shear stresses and vibration inherent in double cardan
shafts.[12][13][14] While the geometric configuration does not maintain
constant velocity for the control yoke that aligns the cardan joints, the
control yoke has minimal inertia and generates little vibration. Continuous
use of a standard Thompson coupling at a straight-through, zero-degree angle
will cause excessive wear and damage to the joint; a minimum offset of 2
degrees between the input and output shafts is needed to reduce control yoke
wear.[15] Modifying the input and output yokes so that they are not
precisely normal to their respective shafts can alter or eliminate the "
disallowed" angles.[16]
The cardan joints within the Thompson Coupling can use roller bearings for
all bearing surfaces; this reduces friction and wear when compared to the
sliding joints used in Rzeppa-type CV joints.[17]
The novel feature of the coupling is the method for geometrically
constraining the pair of cardan joints within the assembly by using, for
example, a spherical four bar scissors linkage (spherical pantograph) and it
is the first coupling to have this combination of properties.[18]
The coupling earned its inventor, Glenn Thompson, the Australian Society for
Engineering in Agriculture Engineering Award.[
"
简单的说,它是基于double cardan CV joint的设计
而double cardan就是两个universal joint通过一个中间轴连在一起,
从而避免universal joint当转角角度变化时两轴相位产生变化
这个thompson coupling相当于是把中间轴去掉,把两个universal joint直接连在一起
然后另外加入约束来保证两者相位同步,于此同时使得两个半轴的偏移角度相同,
或者说对一个总偏移角度,让两个universal joint的子偏移角度对半分
通过这个方法来让作用到每个半轴的法向上的力明显降低,因此也就降低了摩擦和振动
另外因为这个设计不涉及到bearing本身的相对滑动,所以可以用滚动轴承,
而不是像车用CV joint那样需要用一个同时能滑动和滚动的轴承,这方面也更减少损耗
不过我看了下里面说的,这个CV如果长期工作在完全准直的工况,
会导致约束机制(yoke)有很大的磨损,
需要两轴偏角有两度或更高来避免此类磨损
那么或许它更适合用来长期进行angled动力传送
【在 i****x 的大作中提到】
: 有意思
: 这有个设计图，谁能看明白道理。。我看起来，这就是个比较复杂的万向轴，一般万向
: 轴有两个垂直运动面，这玩意不知为啥有四个
| i****x
发帖数: 17565 | 4 谢谢
看来我看的没错，就是两个万向轴捏一起，根本原理是把摩擦对半分
那要是能把三个万向轴捏在一起，岂不是能更顺滑。。。
spherical
【在 p*********e 的大作中提到】
: 看了一下wiki的介绍
: "
: Thompson coupling[edit]
: Thompson coupling from U.S. Patent 7,442,126. Note: drawing on the right
: omits certain components in order to illustrate the control yoke's spherical
: pantograph.
: The Thompson constant velocity joint (TCVJ), also known as a Thompson
: coupling, assembles two cardan joints within each other to eliminate the
: intermediate shaft. A control yoke is added to keep the input and output
: shafts aligned. The control yoke uses a spherical pantograph scissor
| p*********e
发帖数: 32207 | 5 这个不是把摩擦对半分了
是通过那个约束机制让两个子万向节的偏移角度平分
使得彼此对称,从而明显减小轴与轴之间的作用力,也就是压力
压力降下来了摩擦力就降下来了
但那里面只提到这个设计原则和定性的实现方法,
具体那个约束是如何作用的我还没搞明白:)
【在 i****x 的大作中提到】
: 谢谢
: 看来我看的没错，就是两个万向轴捏一起，根本原理是把摩擦对半分
: 那要是能把三个万向轴捏在一起，岂不是能更顺滑。。。
:
: spherical
| s*******e
发帖数: 1298 | 6 这种小装置非常有意思。
都是大牛，以后我也花时间研究研究~~ |
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