Land vehicles – Wheeled – Running gear
Reexamination Certificate
1999-07-23
2002-06-11
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Running gear
C280S086757, C280S086754
Reexamination Certificate
active
06402168
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a steering device used in industrial vehicles. More specifically, the present invention pertains to a steering device having a mechanism for adjusting toe angles.
A typical industrial vehicle such as forklift has a steering device for steering a pair of wheels in accordance with manipulation of a steering wheel. The correspondence between the orientation, or the toe angle, of each steered wheel and the position of the steering wheel must be accurately determined such that the vehicle travels in a straight line when the steering wheel is at the neutral position. However, the correspondence between the toe angles and the position of the steering wheel may be changed by errors produced when machining and assembling the parts of the steering device. The changed correspondence adversely affects the travel of the vehicle.
Japanese Unexamined Patent Publication No. 10-76977 discloses a steering device having a mechanism for adjusting toe angles.
FIG. 16
shows such steering device
71
. The steering device
71
is located in a vehicle axle
79
. A pair of steered wheels
76
are located at the ends of the axle
79
. Each wheel
76
is supported by a knuckle arm
74
. Each knuckle arm
74
is pivotally supported on the associated end of the axle
79
by a kingpin
80
. Each steered wheel
76
, together with the associated knuckle arm
72
, is pivoted about the axis of the kingpin
80
.
The device
71
has a cylinder
73
having an actuator rod
72
. The ends of the actuator rod
72
each extend toward one of the steered wheels
76
. Each knuckle arm
74
is coupled to the corresponding end of the actuator rod
72
by a tie-rod
75
. Each tie-rod
75
and the associated knuckle arm
74
are pivotally coupled to each other by a substantially cylindrical shaft
77
. The tie-rod
75
is pivotally connected to the associated end of the actuator rod
72
by an adjuster pin
78
. Axial movement of the actuator rod
72
is converted into pivoting movement of the knuckle arms
74
about the kingpins
80
by the tie-rods
75
.
Although not illustrated, each adjuster pin
78
includes a support portion and an eccentric portion. The support portion is rotatably supported by the actuator rod
72
and the eccentric portion is radially offset from the axis of the support portion. The tie-rod
75
is connected to the eccentric portion to pivot about the eccentric portion. The adjuster pin
78
also has a hexagonal head the center of which is aligned with the axis of the support portion. Brackets
81
are secured to the ends of the actuator rod
72
by bolts
82
. Each bracket
81
has a hexagonal hole
81
a,
which corresponds to the hexagonal head of the adjuster pin
78
. The hexagonal head is fitted in the hexagonal hole
81
a
so that the pin
78
does not rotate relative to the actuator rod
72
.
Rotating one of the adjuster pins
78
, with the corresponding bracket
81
removed, moves the axis of the eccentric portion about the axis of the support portion. Specifically, since the adjuster pin
78
is rotated about the axis of the support portion relative to the actuator rod
72
, the axis of the eccentric portion is moved along a circle, the radius of which is the distance between the axis of the support portion and the axis of the eccentric portion. Such movement of the axis of the eccentric portion moves the tie-rod
75
. This moves the knuckle arm
74
thereby changing the toe angle of the corresponding steered wheel
76
. The bracket
81
is installed after rotating the adjuster pin
78
by a desired angle. The bracket
81
prevents the adjuster pin
78
from rotating relative to the actuator rod
72
, thereby determining the correspondence between the toe angle and the position of the steering wheel. In this manner, the orientation, or the toe angle, of the steered wheel
86
is adjusted.
In the device
71
, the toe angle of each wheel
76
is adjusted by the corresponding adjuster pin
78
, which is located at the corresponding end of the actuator rod
72
. In order to adjust the toe angles of the steered wheels
76
, the pins
78
must be independently rotated, which complicates the adjustment of the toe angles and extends the time needed for the adjustment.
As shown in
FIG. 16
, the joints of the actuator rod
72
and the tie-rods
75
, or the parts including the pins
78
, are covered by the axle
79
. Thus, adjusting the toe angles is difficult because the axle
79
gets in the way.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a steering device that allows toe angles to be easily adjusted.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, a steering device for steering a pair of wheels about steering axes is provided. The wheels are located at left and right sides of a vehicle, respectively. The device includes left and right knuckle arms for supporting the wheels, respectively, an actuator rod, left and right tie-rods, left and right actuator joints and a toe angle adjusting mechanism. The knuckle arms are supported by the vehicle such that each knuckle arm rotates about the steering axis of the corresponding wheel. The actuator rod reciprocates in the lateral direction of the vehicle and has left and right ends, each end extending toward the corresponding knuckle arm. Each tie-rod connects the corresponding end of the actuator rod to the corresponding knuckle arm. The tie-rods convert reciprocation of the actuator rod into rotation of the knuckle arms. Each actuator joint is located between the corresponding end of the actuator rod and the corresponding tie-rod. The toe angle adjusting mechanism is located at only one of the left and right actuator joints to adjust the toe angle of the corresponding wheel.
The present invention may also be embodied as another steering device for steering a pair of wheels about steering axes. The device includes left and right knuckle arms, an actuator rod, left and right tie-rods, left and right steering joints and a toe angle adjusting mechanism. Each steering joint is located between the corresponding tie-rod and the corresponding knuckle arm. The toe angle adjusting mechanism is located at at least one of the steering joints to adjust the toe angle of the wheel.
The present invention may be embodied in yet another steering device for steering a pair of wheels about steering axes. The device includes left and right knuckle arms, an actuator rod, left and right tie-rods, and a variable pivot joint. The variable pivot joint is located in the steering device and pivotally joins a first member and a second member. The first member is one of the tie-rods and the second member is the actuator rod or a corresponding one of the knuckle arms. The variable pivot joint includes an adjuster pin, a retainer and a fastener. The adjuster pin has a support shaft, an eccentric shaft and an engagement portion. The axis of the support shaft is parallel to and spaced from the axis of the eccentric shaft. One of the first and second members pivots about the axis of the support shaft and the other member pivots about the axis of the eccentric shaft. The adjuster pin is rotated to vary the position of the first member with respect to the second member to adjust the characteristics of the steering device. The retainer engages the engagement portion of the adjuster pin and for locking the adjuster pin with respect to one of the members of the variable pivot joint. The retainer engages the adjuster pin at any one of a plurality of angular engagement positions. Each angular engagement position is spaced from an adjacent angular engagement position by a first angle. The fastener fastens the retainer to one of the members of the variable pivot joint at one of at least two fastening positions, which are separated from one another by a second angle. The second angle is different from the first angle.
Further, the present invention may be embodied as a method of adjusting the toe angles of a pair of steered wheel
Chino Kenji
Iwanaga Yoshihisa
Katae Kenichi
Johnson Brian L.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Luby Matt
Morgan & Finnegan , LLP
LandOfFree
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