U.S. patent application number 13/363665 was filed with the patent office on 2013-08-01 for draft force sensor assembly.
The applicant listed for this patent is Mark S. Earley, Benjamin J. Heimuch, PETER A. KOSMICKI, Edwin R. Kreis, Andrew M. Tilkes. Invention is credited to Mark S. Earley, Benjamin J. Heimuch, PETER A. KOSMICKI, Edwin R. Kreis, Andrew M. Tilkes.
Application Number | 20130192854 13/363665 |
Document ID | / |
Family ID | 48783912 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130192854 |
Kind Code |
A1 |
KOSMICKI; PETER A. ; et
al. |
August 1, 2013 |
DRAFT FORCE SENSOR ASSEMBLY
Abstract
A draft sensing mechanism includes a draft frame adapted to be
attached to a frame of a vehicle. The draft frame has left and
right supports adapted to be coupled to corresponding left and
right draft links. A draft strap has a left end fixed to a front
side of the left support and a right end fixed to a front side of
the right support. The draft strap is deflectable in response to
draft forces applied to the left and right supports. A draft sensor
is attached to the draft strap. The sensor generates a draft signal
in response to deflection of the draft strap.
Inventors: |
KOSMICKI; PETER A.; (Cedar
Falls, IA) ; Heimuch; Benjamin J.; (Cedar Falls,
IA) ; Earley; Mark S.; (Traer, IA) ; Kreis;
Edwin R.; (Waterloo, IA) ; Tilkes; Andrew M.;
(Cedar Falls, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOSMICKI; PETER A.
Heimuch; Benjamin J.
Earley; Mark S.
Kreis; Edwin R.
Tilkes; Andrew M. |
Cedar Falls
Cedar Falls
Traer
Waterloo
Cedar Falls |
IA
IA
IA
IA
IA |
US
US
US
US
US |
|
|
Family ID: |
48783912 |
Appl. No.: |
13/363665 |
Filed: |
February 1, 2012 |
Current U.S.
Class: |
172/7 |
Current CPC
Class: |
B60D 2001/008 20130101;
B60D 1/248 20130101; B60D 1/62 20130101 |
Class at
Publication: |
172/7 |
International
Class: |
A01B 63/02 20060101
A01B063/02 |
Claims
1. A draft sensing mechanism comprising: a draft frame adapted to
be attached to a frame of a vehicle, the draft frame having left
and right supports adapted to be coupled to corresponding left and
right draft links; a draft strap having a left end fixed to a front
side of the left support and a right end fixed to a front side of
the right support, the draft strap being deflectable in response to
draft forces applied to the left and right supports; and a draft
sensor attached to the draft strap, the sensor generating a draft
signal in response to deflection of the draft strap.
2. The draft sensing mechanism of claim 1, wherein: the sensor is
attached to a front side of the draft strap.
3. The draft sensing mechanism of claim 1, wherein: the draft frame
comprises a central body adapted to be attached to a frame of the
vehicle, and the left support projecting from a left front corner
of the body, the right support projecting from a right front corner
of the body.
4. The draft sensing mechanism of claim 3, wherein: the draft strap
is spaced apart forwardly with respect to a lower front end of the
central body.
5. The draft sensing mechanism of claim 1, wherein: the draft strap
has a vertical dimension which is larger than its fore-and-aft
dimension.
6. A draft sensing mechanism comprising: a draft frame adapted to
be attached to a frame of a vehicle, the draft frame having left
and right supports adapted to be coupled to corresponding left and
right draft links, the draft frame comprising a central body
adapted to be attached to a frame of the vehicle, and the left
support projecting from a left front corner of the body, the right
support projecting from a right front corner of the body; a draft
strap having a left end fixed to a front side of the left support
and a right end fixed to a front side of the right support, the
draft strap being deflectable in response to draft forces applied
to the left and right supports; and a draft sensor attached to a
front side of the draft strap, the sensor generating a draft signal
in response to deflection of the draft strap.
7. The draft sensing mechanism of claim 6, wherein: the draft strap
is spaced apart forwardly with respect to a lower front end of the
central body.
8. The draft sensing mechanism of claim 6, wherein: the draft strap
has a vertical dimension which is larger than its fore-and-aft
dimension.
9. A draft sensing mechanism comprising: a vehicle draft frame; a
left draft link support on a left side of the draft frame; a right
draft link support on a right side of the draft frame, the supports
being adapted to be coupled to front ends of respective left and
right draft links, each support having a front side, and the draft
frame having a lower front end which is spaced apart rearwardly
with respect to the front sides of the left and right supports; a
draft strap having a left end fixed to the front side of the left
support and a right end fixed to the front side of the right
support, the draft strap being deflectable in response to draft
forces applied to the left and right supports, the draft strap
comprising a flat body which extends laterally from the left draft
link support to the right draft link support; and a draft sensor
attached to the draft strap, the sensor generating a draft signal
in response to deflection of the draft strap.
10. The draft sensing mechanism of claim 9, wherein: the sensor is
attached to an outer surface of the draft strap.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to a force sensor assembly
for sensing forces, such as the draft forces applied to the
implement hitch of an agricultural tractor.
BACKGROUND OF THE INVENTION
[0002] Agricultural implements can be attached to a three point
hitch of an agricultural tractor. A three point hitch normally
includes a draft sensing mechanism which provides a draft force
signal to a control system which lowers and raises the implement as
a function of sensed draft force and possibly as a function of
other sensed parameters, such as position, engine speed, wheel
slip, etc. Some known production draft sensing mechanisms have a
number of moving parts that require periodic maintenance. This
includes removing mud and dirt accumulation and lubricating a draft
sensor plunger to prevent moisture and dirt contamination. In
certain conditions, accumulated dirt and mud can prevent the
required component movement and can causes false draft force
signals. Future tractor designs will have less room for such draft
sensor components. Thus, it is desired to have a draft sensor which
requires less space, which has no moving parts requiring
lubrication and which does not need to be protected from dirt
accumulation.
[0003] Other known a draft sensing mechanisms have required costly
draft sensing pins, bending bars, and draft sensing shafts. Draft
sensing pins require two instrument pins which double the cost and
decrease the reliability. Certain current draft sensing system on
John Deere four wheel drive tractors measures the deflections of
the draft link mount straps. These straps are large and a large
number of parts are required to measure this signal. The system
also has moving parts. The bending bar and draft sensing shaft
systems have moving parts and require a sealed compartment and a
fair amount of space. A simpler, lower cost and more reliable draft
sensing mechanism is desired.
SUMMARY
[0004] According to an aspect of the present disclosure, a draft
sensing mechanism includes a draft frame adapted to be attached to
a frame of a vehicle. The draft frame has left and right supports
adapted to be coupled to corresponding left and right draft links.
A draft strap has a left end fixed to a front side of the left
support and a right end fixed to a front side of the right support.
The draft strap is deflectable in response to draft forces applied
to the left and right supports. A draft sensor is attached to the
draft strap. The sensor generates a draft signal in response to
deflection of the draft strap. The sensor is preferably attached to
a front side of the draft strap. The draft frame has a central body
adapted to be attached to a frame of the vehicle. The left support
projects from a left front corner of the body, and the right
support projects from a right front corner of the body. The central
body forms a recess and the draft strap spans the recess. The draft
strap has a vertical dimension which is larger than its
fore-and-aft dimension. This draft sensing mechanism mechanically
averages the signal with only a single sensor unit, resulting in a
simpler design, decreased cost and improved reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a perspective side view of a draft sensing
mechanism embodying the invention; and
[0006] FIG. 2 is a bottom view of the draft sensing mechanism of
FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0007] Referring to FIGS. 1 and 2, a draft sensing mechanism 10 is
attached to a draft frame 12 for a work vehicle, such as a tractor
(not shown). The draft frame 12 has a central body 14 on which are
formed forward facing mounting surfaces 16 and 18 for engaging
rearward facing mounting surfaces (not shown) of a tractor frame
(not shown). The draft frame 12 also includes a left draft link
support 20 projecting from a left front corner of the body 14 and a
right draft link support 22 projecting from a right front corner of
the body 14. The left and right supports 20 and 22 are adapted for
coupling to corresponding left and right draft links (not shown).
As best seen in FIG. 1, the lower front end 24 of the body 14 is
spaced apart rearwardly with respect to the front sides of the left
and right supports 20 and 22.
[0008] A draft strap 30 has a left end 32 fixed, such as by bolts
34, to the front side of the left support 20, and a right end 36
fixed, such as by bolts 38, to a front side of the right support
22. Thus, a recess or gap 26 is formed between the lower front end
24 of the body 14 and the draft strap 30. Also, the draft strap 30
is spaced apart forwardly with respect to the lower front end 24 of
the body 14. The draft strap 30 has vertical dimension which is
larger than its fore-and-aft dimension, and its stiffness in the
vertical direction is greater than its stiffness in the horizontal
direction --it is more flexible in the horizontal direction so that
it is more sensitive to horizontal draft forces. The draft strap 30
will be deflected by draft forces applied to the left and right
supports 20 and 22.
[0009] A strain gauge sensor 40 is attached with adhesive and
screws or bolts to the front side of the draft strap 30. For
example, Loctite 638 may be used to bond the sensor 40 to the strap
30. Sensor 40 is preferably a full strain gage bridge and is
preferably a multi-element bolt-on strain sensor, such as a Series
460 2-Hole Sensor manufactured by Datum Electronics. The sensor 40
generates a draft or draft force signal in response to deflection
of the draft strap 30. A cable 42 connects the sensor 40 to a
conventional electrical connector 44 for communicating the draft
signal to draft control system (not shown) of the tractor (not
shown).
[0010] This draft sensing mechanism 10 mechanically averages the
horizontal draft load between the left draft link support 20 and
the right draft link support 22. This sensed horizontal load or
draft force is used as an input to a draft control system. The
structure of the draft frame 12, the left draft link support 20 and
the right draft link support 22 is flexible for horizontal load
measurement and stiff in the vertical load direction. The shape of
the draft frame 12 and the placement of the draft sensing strap 30
also helps to maximizes horizontal draft signal and minimizes
vertical load signal. The draft sensing system requires very little
space and does not require periodical lubrication and
maintenance.
[0011] While the disclosure has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description is to be considered as exemplary and not
restrictive in character, it being understood that illustrative
embodiments have been shown and described and that all changes and
modifications that come within the spirit of the disclosure are
desired to be protected. It will be noted that alternative
embodiments of the present disclosure may not include all of the
features described yet still benefit from at least some of the
advantages of such features. Those of ordinary skill in the art may
readily devise their own implementations that incorporate one or
more of the features of the present disclosure and fall within the
spirit and scope of the present invention as defined by the
appended claims.
* * * * *