Bolt fastener

A bolt fastener (1) is attachable to a bolt (23) by pressing the base (3) onto the bolt to receive the bolt in a receiving hole (2) of the base (3), while the fastener (1) has an increased pulling resistance force (pulling load) against a pulling force of the fastener from the bolt. An inner wall (9) of the bolt receiving hole (2) is provided with a pair of opposed engagement means (10) member into engagement with a threaded portion of the bolt as the received in the bolt receiving hole (2). Each of the engagement means (10) comprises a plurality of resilient arms (15,17) extending from the inner wall (9) of the bolt receiving hole (21) toward the center of the hole and a plate-like engagement portion (18) supported by the resilient arms to extend longitudinally with respect to the bolt receiving hole. Each of the opposed surfaces of the engagement portions (18) of the paired engagement means (10) is formed with a plurality of multi-stepped engagement pawls (19) arranged longitudinally with respect to the bolt receiving hole (2) for engagement with threaded portion of the bolt (23).

BACKGROUND OF THE INVENTION 
The present invention relates to a bolt fastener comprising a base having a 
bolt receiving hole formed to receive a bolt projecting from a panel, with 
an inner wall of the bolt receiving hole formed with a pair of opposed 
engagement means to engage with a threaded portion of the received bolt 
and, more specifically, to a bolt fastener adapted to hold a fuel pipe, a 
brake pipe or the like through its engagement with a bolt such as a stud 
bolt projecting from the panel of a vehicle body or the like. 
Bolt fasteners capable of holding a fuel pipe, a brake pipe or the like to 
a panel such as a vehicle body by making use of a stud or a bolt provided 
to project from the panel have been developed. A typical example of such a 
bolt fastener has a base formed with a bolt receiving hole to receive a 
bolt fixed to the panel, and a pipe holder which extends integrally 
sideways from the base and holds pipes pressed into opened portions 
thereof, and the bolt receiving hole of the base is formed with engagement 
pawls to engage with a threaded portion of the received bolt. In the 
mounting operation, where the pipes are held in the pipe holders, the 
receiving hole of the base is held to the bolt and the base is simply 
pressed down. The base is then fixed to the panel and the pipes held in 
the pipe holder are fixedly placed on the panel. 
Such a bolt fastener is convenient in that pipes can be mounted on the 
panel when the base is simply pressed onto the bolt. Nevertheless, even 
this bolt fastener has a problem still to be solved. The problem with 
conventional bolt fasteners is that only limited portions of the 
engagement pawls catch the threaded portion of the bolt, which makes it 
impossible to increase the resistance force (pulling load) against a force 
to pull the bolt fastener out from the bolt. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a bolt 
fastener that can have an increased resistance force (pulling load) 
against a force to pull the fastener out from the bolt while maintaining 
operational facility that allows the fastener to be attached simply when 
the receiving hole of the base is pressed onto the bolt. 
The present invention provides a bolt fastener comprising a base having a 
bolt receiving hole formed to receive a bolt projecting from a panel 
therein, with the bolt receiving hole including an inner wall formed with 
a pair of opposed engagement means for engagement with a threaded portion 
of the received bolt; characterised in that each of the engagement means 
comprises a plurality of resilient arms extending from the inner wall of 
the bolt receiving hole toward the centre of the hole, and a plate-like 
engagement portion which is supported by the resilient arms and extend 
longitudinally with respect to the bolt receiving hole, and the opposed 
surfaces of the engagement portions are provided with a plurality of 
engagement pawls translatedly arranged longitudinally with respect to the 
bolt receiving hole for engagement with a threaded portion of the bolt. 
The above structure allows the engagement pawls of the engagement portions 
to engage with a plurality of threads to ensure a large engagement area, 
and the engagement of the engagement pawls is maintained stably and firmly 
by the resilience of the resilient arms supporting the engagement 
portions. Therefore, the fastener has an increased engagement force with 
the bolt and the resistance force (pulling load) against a force to pull 
out the fastener from the bolt can be increased. 
The resilient arms of each engagement means are preferably formed as four 
resilient arms to support the four corners of each engagement portion. It 
is preferred that each resilient arm extends toward the inlet side of the 
bolt receiving force, and makes an acute angle with the inner wall of the 
bolt receiving hole, and a parallelogram can be formed by the inner wall 
of the receiving hole, the resilient arm in an inlet side portion of the 
receiving hole, the resilient arm in an outlet side portion of the 
receiving hole, and an engagement portion supported by the resilient arms. 
Resilience of the resilient arms forming the parallelograms, rigidity of 
the engagement portions and the multi-step engagement pawls ensure that 
the engagement pawls engage with whichever threads coming to engagement 
positions, and that the engagement portions engage with the bolt stably in 
a large engagement area. It is preferable to form cutouts at the portions 
of each inner wall adjacent the root of the resilient arms so that the 
resilient arms can change their shape easily. It is also preferable to 
make the bolt receiving hole of the base in an elongated form so as to 
absorb an offset of the mounting positions of the bolts on the panel, and 
to make the engagement portions wide enough correspondingly to the 
elongated hole. Preferably, each engagement portion is formed with a 
reinforcement rib on the opposite side to its engagement pawls so as to 
have a high rigidity.

The bolt fastener 1 is formed as a one-piece pipe holder moulded from a 
plastics material. As illustrated, the bolt fastener 1 of the present 
invention is suitable for use as a pipe holder, but it is not limited to 
the illustrated bolt fastener configuration. Other examples of bolt 
fasteners according to the invention include, a fastener to join a 
plurality of panels placed one above each other and a fastener to connect 
another member to a panel through engagement thereof with a bolt 
projecting from the panel. 
DETAILED DESCRIPTION OF THE INVENTION 
In the embodiment of FIG. 1, the bolt fastener 1 has a base 3 formed with a 
bolt receiving hole 2 to receive a bolt projecting from the panel and a 
pipe holder 7 extending sideways integrally from the base 3 for holding a 
pipe 6 by pressing the pipe 6 into an opening 5. As shown in FIG. 2, the 
bolt receiving hole 2 of the base 3 is formed to define a space which is 
substantially rectangular in section, with inner walls 9,9 facing each 
other which form outline of the bolt receiving hole 2. As shown in FIG. 1, 
the lower end of the bolt receiving hole 2 is on the inlet side for the 
bolt and the upper end is on the outlet side for the bolt, which 
penetrates the hole and extends from this portion. As shown in FIG. 3, a 
hole 2a on the outlet side is formed as an elongated hole so as to absorb 
an offset of the mounting positions of the bolts on the panel. The inner 
walls 9,9 of the bolt receiving hole 2 are respectively formed with 
engagement means 10 to engage with a threaded portion of the bolt. In FIG. 
1, the base 3 is formed with windows 11 on its sides in order to form 
engagement means 10 in the bolt receiving hole 2 by moulding and a column 
13 is formed in the centre of each window for maintaining the strength of 
the base 3 uniformly. From the bolt inlet side of the base 3, resilient 
holding members 14 to hold the pipes 6 extend toward the respective bases 
of the openings 5 of the pipe holder 7. 
Engagement means 10 of a specific structure are provided on the inner walls 
9 of the bolt receiving hole 2. The engagement means 10 are described in 
the following, with reference to FIGS. 1 to 5 and FIG. 6. Each of the 
engagement means 10 is made up of a plurality of resilient arms 15,17 
extending from the inner wall 9 toward the centre of the hole, and a 
plate-like engagement portion 18 which is supported by the resilient arms 
15 and 17 and extends longitudinally with respect to the bolt receiving 
hole 2. Each of opposed surfaces of the engagement means 18, which faces 
the threaded portion of the bolt, is provided with engagement pawls 19 to 
engage with the threaded portion of the bolt. The engagement pawls are 
multiple steps arranged longitudinally with respect to the bolt receiving 
hole. On the opposite side to the engagement pawls 19, each of the 
engagement portions 18 is formed with a reinforcement rib 21 to maintain 
high rigidity. 
The resilient arm 15 (17) of each engagement means 10 respectively support 
the four corners of the plate-like engagement portion 18. In other words, 
each of the engagement portions 18 is supported by four resilient arms 15 
and 17. Each resilient arm 15 (17), facing the inlet side of the bolt 
receiving hole 2 (the lower end side of FIG. 6), makes an acute angle 0 
with an inner wall 9, as can be seen from FIG. 6. 
Accordingly, when the bolt receiving hole 2 is viewed from one side (i.e. a 
window 11), each engagement means 10 defines a parallelogram formed by the 
engagement portion 18, the resilient arm 15 supporting a portion of the 
engagement portion on the inlet side of the receiving hole, the resilient 
arm 17 supporting a portion of the engagement portion on the outlet side 
of the bolt receiving hole, and a portion of the inner wall 9 between the 
bases of the resilient arms 15 and 17. The parallelograms are shown 
schematically in FIG. 6(A). In this Figure, vertical sides 9 (inner walls) 
and 18 (engagement portions) are rigid and never change their forms, 
whereas upper and lower sides 17 and 15, extending diagonally are variable 
in shape. Therefore, the two parallelograms change the shapes so as to 
come closer to or get away from each other while the sides 18, i.e. the 
engagement portions 18 remain to be vertical. This means that the 
engagement portions 18 are held parallel to the threaded surface of the 
bolt. In the base portions of the resilient arms 15 and 17 in the inner 
walls 9, cutouts 22 are formed to enable the resilient arms to change 
their shapes easily, as best shown in FIGS. 5 and 6. 
The operation to mount the pipes 6 on a panel 23 by using the bolt fastener 
1 of the above-described structure are explained with reference to FIGS. 7 
and 8. At predetermined points on the panel 23, which is a vehicle body or 
the like, bolts 25 for example, stud bolts, are fixed by welding or some 
other means. Bolt fasteners 1 are attached to predetermined positions of 
the pipes 6. The pipes 6 attached with bolt fasteners 1 at the 
predetermined positions thereof are brought to a place where the panel 23 
is. Each bolt fastener 1 is pressed onto the corresponding bolt 25 to 
receive the bolt in the bolt receiving hole 2 (see FIG. 7). At the 
beginning of and during this pressing operation, as shown in FIG. 7(A), 
the resilient arms 15 and 17 are bent from the position shown by broken 
lines to the position indicated by solid lines, and then the engagement 
portion 18 then moves away from the threaded surface of the bolt 25. As 
mentioned earlier, the arms 15 and 17 are resilient while the engagement 
portions 18 and the inner walls 9 are rigid, and the resilient arms 15 and 
17, the engagement portion 18 and the inner wall 9 form a parallelogram, 
so that the engagement portion 18 moves in the direction indicated by an 
arrow 26, in parallel with the inner wall 9. Since the surface of the 
inner wall 9 is substantially parallel to the threaded surface of the bolt 
25, the engagement portion 18 moves from the bolt 25, parallel to the 
threaded surface of the bolt. 
As illustrated in FIG. 8, upon completion of pressing the bolt fastener 1, 
the multi-step engagement pawls 19 of the engagement means 10 come into 
engagement with the complete threads of the bolt 25. When the pressing 
operation is finished, the resilient arms 15 and 17 which have bent as 
shown in FIG. 7(A) return from the positions shown by broken lines to 
those of solid lines as indicated by an arrow 27 in FIG. 8(A). In 
returning, the engagement portion 18 is moved from the position shown by a 
broken line to the position shown by a solid line while maintaining its 
perpendicular form, and comes into engagement with the threaded surface of 
the bolt 25. Accordingly, it is ensured that the multi-step engagement 
pawls 19 formed on the bolt-side surfaces of the engagement portions 18 
engage with correspondingly positioned threads of the bolt 25, 
respectively. Thus, each of the engagement portions 18 and the threads of 
the bolt 25 are engaged with each other over a wide area and the 
engagement portion 18 is capable of engaging with the bolt 25 with an 
increased force. The engagement pawls 19 of one of the engagement portions 
18 is staggered heightwise from the engagement pawls 19 of the other 
engagement portion 18 by a length corresponding to a half pitch of the 
threads of the bolt 25. This arrangement allows the engagement pawls 19 to 
engage fully with the corresponding threads of the bolt 25 and increases 
the engagement force of the engagement means with the bolt. 
As described above, when the fastener 1 engages with the bolt 25 and is 
fixed, the pipes 6 are mounted on the panel 23. Because the multi-step 
engagement pawls 19 of the engagement portions 18 engage with the threaded 
portion of the bolt 25 at many points and their engagement is stable, the 
bolt fastener 1 has an increased resistant force against a force to pull 
out it from the bolt 26 (pulling load) and the pipes never leave the 
panel. 
According to the present invention, the engagement pawls of the engagement 
portions engage with a plurality of threads to maintain a large engagement 
area, and engagement of the engagement pawls with the bolt is maintained 
stably and firmly owing to the resilience of the resilient arms supporting 
the engagement portions. Therefore, it has an increased engagement force 
with the bolt and the resistance force against a force to pull the 
fastener out from the bolt is also increased. In the present invention, it 
may be arranged that each resilient arm, facing the inlet side of the bolt 
receiving hole, makes an acute angle with an inner wall of the bolt 
receiving hole so as to form a parallelogram by a portion of the inner 
wall of the receiving hole, the resilient arm in the inlet side portion of 
the receiving hole, the resilient arm in the outlet side portion of the 
receiving hole and the engagement portion supported by the resilient arms. 
This allows the engagement pawls to engage reliably with threads in any 
positions of the bolt and the resilient arms enable each of the engagement 
portions to contact the bolt appropriately and to engage with the bolt 
stably in a wide engagement area.