Motor vehicles – Steering gear – With fluid power assist
Reexamination Certificate
2000-09-26
2001-08-14
Boehler, Anne Marie (Department: 3618)
Motor vehicles
Steering gear
With fluid power assist
C180S435000
Reexamination Certificate
active
06273209
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal structure of a tie rod mounting portion in a center take-off type power steering apparatus for a vehicle. More particularly to a seal structure of a tie rod mounting portion in a center take-off type power steering apparatus which improves a reliability for seal in a bolt passing portion of a dust boot passed through by a bolt in the tie rod mounting portion so as to be gripped.
2. Description of the Related Art
The conventional seal structure of the tie rod mounting portion in the center take-off type power steering apparatus is made as follows (refer to Japanese Patent Application No. 9-153292).
In
FIG. 8
, the structure is made such that respective inner ends of a pair of right and left tie rods
05
and
05
are respectively connected to a rack shaft
04
by a pair of right and left bolts
09
and
09
passing through a guide shoe
07
sliding within a notch groove
06
formed along a lengthwise direction of a gear box housing
03
. It then moves laterally in correspondence to a lateral motion of the rack shaft
04
while being guided by the guide shoe
07
.
A substantially center portion of a dust boot
011
is gripped between the guide shoe
07
and the respective inner ends of a pair of right and left tie rods
05
and
05
by being passed through by a pair of right and left bolts
09
and
09
. Then, a metal fitting
013
is interposed between the dust boot
011
and the respective inner ends of a pair of right and left tie rods
05
and
05
, and a collar
010
is fitted between the guide shoe
07
and the respective bolts
09
and between the dust boot
011
and the respective bolts
09
with overriding among the rack shaft
04
, the guide shoe
07
and the guide boot
011
.
One end portion (a lower end portion in
FIG. 8
) of the collar
010
protrudes from the dust boot
011
so as to be brought into contact with the metal fitting
013
. Further, an annular protruding wall
025
is formed in the dust boot
011
so as to surround one end portion of the collar
010
and be brought into contact with the metal fitting
013
.
Accordingly, as shown in
FIG. 9
, water going to enter from a direction of A is prevented by contact between the metal fitting
013
and the respective inner ends of a pair of right and left tie rods
05
and
05
. The water going to enter from a direction of B is prevented by contact between the metal fitting
013
and one end portion of the collar
010
and contact between the metal fitting
013
and the annular protruding wall
025
of the dust boot
011
. In the manner mentioned above, the water is prevented from entering into the dust boot
011
and further entering into the gear box
03
.
However, since the conventional seal structure of the tie rod mounting portion in the center take-off type power steering apparatus is made as mentioned above, for example, there is generated a risk that a compressive reaction force F from the dust boot
011
acts on the seal structure as shown in FIG.
9
. The force generates a stress in respective portions of the seal structure and breaks the seal structure, thereby reducing a waterproof performance when a force is transmitted to the dust boot
011
via the collar
010
in accordance with a lateral motion of the rack shaft
04
. As a result, the dust boot
011
is extended and compressed to a rack end at a maximum stroke of the rack shaft
04
. In this case, in
FIG. 9
, an arrow D indicates a moving direction of the rack shaft
04
and the tie rods
05
and
05
.
In particular, the inner surface side of the dust boot
011
is pressed by the guide shoe
07
in the contact portion between the metal fitting
013
and the annular protruding wall
025
of the dust boot
011
. Therefore, the compression reaction force F acts in a direction of contact with the metal fitting
013
in the outer surface side of the dust boot
011
and deforms the outer peripheral portion of the metal fitting
013
so as to bend outward toward the tie rods
05
and
05
side.
The metal fitting
013
is deformed in this manner, whereby a gap is generated in the contact portion between the metal fitting
013
and the annular protruding wall
025
. There occurs a situation where water flowing towards the direction of B enters into the dust boot
011
via the gap and further into the gear box housing
03
.
This situation is also generated in the same manner in the case that a tensile reaction force acts on the seal structure. Due to generation of this matter, there is a risk that a reliability with respect to the seal structure of the tie rod mounting portion in the center take-off type power steering apparatus is damaged.
In particular, since the compressive reaction force F and the tensile reaction force is further strengthened in the case that snow or the like are accumulated on a bellows portion of the dust boot
011
in winter season and the bellows can not move, the risk mentioned above is further increased.
The applicant of the present application has made an original idea of a seal structure of a tie rod mounting portion in a center take-off type power steering apparatus which can solve the problems mentioned above. It is provided in the conventional seal structure of the tie rod mounting portion in the center take-off type power steering apparatus, and can prevent the stress from being generated in the seal structure even when the force is transmitted to the dust boot via the collar. This happens in accordance with the lateral motion of the rack shaft and the dust boot is extended and compressed to the rack end at the maximum stroke of the rack shaft, thereby maintaining a waterproof performance and improving a reliability of the seal, and has filed a patent application (refer to Japanese Patent Application No. 11-1054).
SUMMARY OF THE INVENTION
The present invention intends to solve the above problems so as to improve a reliability of seal in a center take-off type power steering apparatus structured such that respective inner ends of a pair of right and left tie rods are swingably connected to a leg portion of a T-shaped connection member. Both arm portions of the T-shaped connection member are respectively connected to a rack shaft by a bolt passing through a guide shoe sliding within a notch groove formed along a lengthwise direction of a gear box housing. The respective inner ends of a pair of right and left tie rods laterally move in accordance with a lateral motion of the rack shaft while being guided by the guide shoe. A center portion of a dust boot is gripped between the guide shoe and both of the arm portions of the T-shaped connection member by being passed through. A collar is fitted between the guide shoe and the bolt and between the dust boot and the bolt so as to override between the rack shaft, the guide shoe and the dust boot. Also, one end portion of the collar protrudes from the dust boot so as to be brought into contact with the arm portion of the T-shaped connection member.
In accordance with the present invention, there is provided a seal structure of a tie rod mounting portion in a center take-off type power steering apparatus structured such that respective inner ends of a pair of right and left tie rods are swingably connected to a leg portion of a T-shaped connection member. Both arm portions of the T-shaped connection member are respectively connected to a rack shaft by a bolt passing through a guide shoe sliding within a notch groove formed along a lengthwise direction of a gear box housing. The respective inner ends of a pair of right and left tie rods laterally move in accordance with a lateral motion of the rack shaft while being guided by the guide shoe. A center portion of a dust boot is gripped between the guide shoe and both of the arm portions of the T-shaped connection member by being passed through by the bolts. A collar is fitted between the guide shoe and the bolt and also between the dust boot and the bolt so as to override between the rack shaft, the guide shoe and the dust boot. One end po
Hamano Satoshi
Saito Tatsuya
Boehler Anne Marie
Orum & Roth
Showa Corporation
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