Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Nonmetallic element
Reexamination Certificate
1999-10-27
2001-07-17
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Nonmetallic element
C464S078000, C464S051000, C464S100000, C403S306000
Reexamination Certificate
active
06261182
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coupler apparatus for a rotation sensor for detecting rotation of a rotating shaft such as a kingpin in vehicles.
Generally, in forklifts, pivoting of a rear axle is limited so that the vehicle body does not incline excessively from centrifugal force when turning. The pivoting of the rear axle is controlled according to, for example, the velocity of the vehicle and the steering angle. Japanese Examined Patent Publication No. 4-24270 describes a method for detecting the steering angle. In this publication, a displacement sensor attached to a steering cylinder detects the piston displacement, and the steering angle is calculated from the displacement. However, using this method, it is difficult to obtain the steering angle. Therefore, the present applicant devised a potentiometer located on an upper bracket of an axle beam for detecting the pivoting angle of a kingpin and for obtaining the steering angle from the detected pivoting angle.
As shown in
FIG. 21
, a potentiometer
52
for detecting the rotation of the kingpin
10
is mounted on the upper bracket
51
supporting a kingpin
50
in a rear axle beam. The potentiometer
52
is fixed to the upper bracket
51
through a sensor support plate
54
so that the potentiometer
52
is located above a bearing hole
53
in which the kingpin
50
is supported. The potentiometer
52
is fixed to the support late
54
by screws (not shown), and the support plate
54
is fixed to an upper bracket
51
by bolts (not shown). An input shaft
55
of the potentiometer
52
passes through the through hole
54
a
toward the kingpin
50
, and a body
56
of the potentiometer
52
is fixed to the support plate
54
. The axis of the input shaft
55
is aligned with the axis of the kingpin
50
. A coupling portion
55
a,
the cross section of which is D-shaped, is formed at the distal end of the input shaft
55
, and the coupling portion engages a D-shaped coupling hole
57
in the upper end of the kingpin
50
. This prevents relative rotation between the input shaft
55
and the kingpin
50
.
Dimensional inaccuracy of parts occurs, and this may offset the axis of the input shaft
55
from the axis of the kingpin
50
. Roller bearings wear after a long period of use, and this may cause the axis of the kingpin
50
to shift from the original position at the center of the bearing hole
53
. This may also offset the axis of the input shaft
55
from the axis of the kingpin
50
. As a result, a radial force is applied from the kingpin
50
to the input shaft
55
, which may degrade the detection sensitivity and durability of the potentiometer
52
. If the radial force becomes excessive, the potentiometer
52
may be damaged.
It is possible to prevent the input shaft
55
from receiving the radial force from the kingpin
50
by providing a clearance between the kingpin
50
and the input shaft
55
. However, this may cause slack between the input shaft
55
and the kingpin
50
in the rotational direction and may degrade detection sensitivity.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide an installation structure for a rotation detector that prevents application of a radial force to an input shaft and slack between a rotational shaft and the input shaft, thus improving durability and detection sensitivity of the rotation detector.
To achieve the objective, the present invention provides an coupler apparatus for a rotation detector, wherein the rotation detector is fixed to a support member supporting the rotational shaft such that an input shaft of the rotation detector is coupled to and does not rotate with respect to the rotational shaft and such that the axis of the input shaft is substantially aligned with the axis of the rotational shaft. The coupler apparatus is characterized in that the input shaft is coupled to the rotational shaft through a rotation transmitter that permits misalignment of the axis of the input shaft from the axis of the rotational shaft by elastic deformation while limiting relative rotation of the input shaft with respect to the rotational shaft.
The input shaft of the rotation detector is coupled to the rotational shaft through the rotation transmitter such that relative rotation of the input shaft with respect to the rotational shaft is prevented and the axis of the input shaft is substantially aligned with the axis of the rotational shaft. When the axis of the input shaft is offset from the axis of the rotational shaft, the rotation transmitter is elastically deformed, which permits the misalignment while limiting relative rotation between the input shaft and the rotational shaft. Accordingly, when the axis of the input shaft is offset from the axis of the rotational shaft, radial force applied from the rotational shaft to the input shaft is absorbed and reduced, and the rotation of the rotational shaft is transmitted to the input shaft. This prevents wear and damage caused by radial force and also prevents slack between the input shaft and the rotational shaft in the rotational direction, which improves detection accuracy.
The rotation transmitter includes a coupling recess located at an end of either the rotational shaft or the input shaft, and a coupling shaft is located at an end of the other shaft. The coupling shaft is placed in the coupling recess, and an elastic coupler that elastically couples the coupling recess with the coupling shaft connects the two together.
The elastic coupler, which couples the coupling recess, which is located in one end of the rotational shaft or the input shaft, with the coupling shaft, which is located at an end of the other shaft, permits misalignment of the coupling recess from the coupling shaft and limits relative rotation of the coupling recess to the coupling shaft. This simplifies the structure and reduces the number of parts and installation steps.
In one embodiment, the elastic coupler includes an engaging portion that integrally rotates with the coupling recess and an elastic member having a fitting portion in which the coupling shaft is inserted to integrally rotate with the elastic member.
The elastic member is coupled to the coupling recess to integrally rotate with the coupling recess by engagement of the engaging portion of the elastic member with the coupling recess. Similarly, the elastic member is coupled to the coupling shaft to integrally rotate with the coupling shaft by engagement of the coupling shaft with the fitting portion of the elastic member. Accordingly, the elastic member, which engages the coupling shaft and the coupling recess, respectively, to integrally rotate with them, limits relative rotation between the input shaft and the rotational shaft and permits misalignment of their axes by elastic deformation. The elastic coupler is made of elastic material that is easy to form.
The coupling recess may be located in the end of the rotational shaft, and the coupling shaft may be located at the end of the input shaft. In this case, the coupling shaft and the coupling recess are easily machined.
In one embodiment, the coupling recess includes first and second columnar holes. The first columnar hole is coaxial with the rotational shaft, and the axis of the second columnar hole is parallel to the axis of the first columnar hole. The engaging portion of the elastic member includes a first body corresponding to the first hole and a second body corresponding to the second hole. In this case, the coupling recess stops relative rotation. Only one drilling is necessary for forming each of the first and second holes, which reduces time spent for machining the coupling recess.
The cross section of the coupling shaft may be D-shaped, and the fitting portion of the elastic member may be a D-shaped engaging hole that passes through the first body. In this case, an existing rotation detector, the coupling shaft of which has a D-shaped cross section, can be used.
When the elastic member is made of synthetic rubber, formation of the elastic member is easier.
In one embodiment, a
Chino Kenji
Hyodo Masaya
Ishikawa Kazuo
Iwanaga Yoshihisa
Browne Lynne H.
Dunwoody Aaron M
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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