Handgrip with built-in heater

A cylindrical rubber handgrip body to be connected to a handle bar pipe of, for example, a motor cycle, has a sheet-like heater embedded therein, and a power supply cord soldered to the heater and extending out of a side face of the grip body. The power supply cord extends inside the handgrip body along the circumference thereof over at least half a turn. A cord support of a high stiffness is provided in a cord exit portion of the handgrip body, for bearing the pulling force that acts on the power supply cord. Both the cord support and the handgrip body bear the pulling force that acts on the power supply cord and reduce the pulling force that is transmitted by the cord to the soldered connection to the heater.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a handgrip with a built-in heater and, 
more particularly, to a handgrip with a built-in heater for motor cycles. 
2. Description of the Related Art 
A conventional handgrip with a built-in heater as shown in FIG. 13 
comprises a cylindrical rubber handgrip body 2A fitable to the handle bar 
pipe 1 of a motor cycle, a reinforcing plate 3 having a transverse 
sectional shape of an arc, and a sheet-like heater 4, such as an FPC 
heater. The reinforcing plate 3 and the heater 4 are integrally embedded 
in the handgrip body 2A. The sheet-like heater 4 is connected to a power 
supply cord 5 by a soldered connection 4a. 
However, there is a danger that the power supply cord 5 may be disconnected 
at the soldered connection 4a from the sheet-like heater 4 when the cord 5 
extending out from the handgrip body 2A is pulled by a hand or other 
external objects accidentally hitting the cord 5, or by turning the 
handgrip body for throttle operation in the case of the right-side 
handgrip whose handgrip body is connected to the throttle pipe. 
Technologies for increasing the structural strength of the connection 
between the power supply cord and the sheet-like heater have been 
proposed. For example, as shown in FIG. 14, a ring 7 provided with cord 
clips 7a for clamping a cord 5 is embedded integrally in a handgrip body 
2B so that the clamping of the cord 5 by the ring 7 (the clips 7a) 
prevents pulling forces from acting on the soldered connection 4a between 
the cord 5 and an FPC heater 4. FIG. 14 further shows a throttle pipe 8. 
In another technology (not shown), the end of a power supply cord is 
provided with a power supply end connector that is connected to a 
heater-end connector provided in the handgrip body. 
However, although the aforementioned technologies ensure high strength of 
the connection between the sheet-like heater and the power supply cord, 
the provision of the ring 7 or the connector in the handgrip body 
complicates the construction of the handgrip, and increases the size of 
the cord exit portion of the handgrip body, interfering with the operation 
of switches or the like disposed next to the handgrip. 
SUMMARY OF THE INVENTION 
The present invention is intended to solve the above-stated problems of the 
conventional art. It is an object of the invention to provide a handgrip 
with a built-in heater that has a simple construction in which a power 
supply cord soldered to a sheet-like heater is led out sideways from the 
handgrip body, and that eliminates the danger of accidental disconnection 
at the soldered connection between the power cord and the sheet-like 
heater without increasing the size of the cord exit portion of the 
handgrip body. 
To achieve the aforementioned objects, according to an aspect of the 
invention, there is provided a handgrip with a built-in heater comprising: 
a heater provided inside a handgrip body; a power supply cord that is 
connected for electrical connection to the heater and that extends out of 
the handgrip body; and means for damping pulling force that acts on the 
power supply cord, within a length of the power supply cord between a site 
where the power supply cord extends out of the handgrip body and a site 
where the power supply cord is connected for electrical connection to the 
heater. 
In a preferred construction of the aforementioned pulling force damping 
means, the handgrip body has a generally circular sectional shape, and the 
power supply cord extends inside the handgrip body in a substantially 
circumferential direction, over at least a half turn, and then extends out 
of the handgrip body. The handgrip of the invention may be suitably 
connected to the handle bar pipe of a motor cycle. 
As a more specific construction of the pulling force damping means, the 
handgrip with a built-in heater of the invention may comprise a 
heater-reinforcing inner piece fixed inside the handgrip body, the inner 
piece having a cord placement groove in which the power supply cord is 
disposed. 
As another preferred construction of the pulling force damping means, the 
handgrip with a built-in heater may comprise a cord support disposed 
substantially at the site where the power supply cord extends out of the 
handgrip body, the cord support having a higher stiffness than the 
handgrip body and being capable of bearing pulling force that acts on the 
power supply cord. The cord support may be formed together with the inner 
piece. In addition, the cord support may extends substantially in the form 
of an arch across the cord placement groove, so that the power supply cord 
extends passing the cord support, and then extends out of the handgrip 
body. 
According to another aspect of the invention, there is provided a handgrip 
with a built-in heater comprising: a heater disposed inside a handgrip 
body; a power supply cord that is electrically connected to the heater and 
that extends from the heater along a generally annular portion of the 
handgrip body and then extends out of the handgrip; and a cord support 
disposed substantially at the site where the power supply cord extends out 
of the handgrip body, the cord support having a higher stiffness than the 
handgrip body and being capable of bearing pulling force that acts on the 
power supply cord. 
The handgrip body may be connected to a right hand-side handle bar pipe 
provided with throttle means, and the power supply cord may extend from 
the heater along the generally annular portion in the same direction as 
the direction in which the throttle means is turned. 
According to the invention, since a considerable length of the power supply 
cord extending from the connections to the sheet-like heater is embedded 
within the handgrip body, preferably, with that length of the power supply 
cord turning through the cord placement groove over at least a half turn, 
the handgrip body becomes able to bear the forces that act on the power 
supply cord, reducing the pulling forces that act on the soldered 
connection to the heater. 
In addition, the cord support of a high stiffness provided at the cord exit 
portion for bearing the forces that act on the power supply cord will also 
reduce the forces that act on the soldered connection to the heater.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described 
hereinafter with reference to the accompanying drawings. 
A first embodiment of the present invention will be described with 
reference to FIGS. 1-7. A cylindrical handgrip body 10 whose exterior is 
formed of rubber is fitted over a throttle pipe 30 (see the cross sections 
shown in FIGS. 6, 7) rotatably connected to a handle bar pipe 40 of a 
motor cycle, thus forming a right-side handgrip. The handgrip body 10 
comprises a semi-cylindrical inner piece 12 formed of a synthetic resin, a 
flexible printed-circuit board heater circuit (hereinafter, referred to as 
"FPC heater") 20 laid on an outer peripheral face of the semi-cylindrical 
inner piece 12, and a cover rubber layer 16 substantially forming the 
shape of the handgrip body 10. A portion of the cover rubber layer 16 is 
formed together with the FPC heater 20 so that the FPC heater 20 is 
sandwiched and extends between the cover rubber layer 16 and the inner 
piece 12. The cover rubber layer 16 has a flange at the inside end of the 
handgrip body 10. 
The inner peripheral face of the inner piece 12 is provided with a rubber 
layer 17 for the press-fitting to the pipe. The rubber layer 17 is 
integrally connected to the cover rubber layer 16 and extends in a grip 
formation (made up of rubber layer bands 17a extending in the direction of 
the axis of the handgrip body 10, and rubber layer bands 17b extending in 
the circumferential direction) as shown in FIGS. 1, 2. More specifically, 
formed in the inner peripheral face of the inner piece 12 are shallow 
grooves 15a, 15b extending and connecting with each other in the form of a 
grid. The grooves 15a, 15b are filled with the rubber layer 17 (the rubber 
layer bands 17a, 17b) so that the rubber layer 17 is flush with the inner 
peripheral face of the inner piece 12. When the throttle pipe 30 is 
inserted into the handgrip body 10, the rubber layer 17 on the inner piece 
12 is pressed against the throttle pipe 30, thus adding to the adhesion 
strength between the handgrip body 10 and the throttle pipe 30. 
The FPC heater 20 sandwiched between the cover rubber layer 16 and the 
inner piece 12 has a sectional structure in which a copper foil strip 
pattern P serving as a heat source is laminated with a base film and an 
over film. When developed or laid flat, the FPC heater 20 assumes a 
substantially rectangular shape as shown in FIG. 3. A lead-out portion 21 
for connection to a power source is formed on a length-end edge of the FPC 
heater 20. The lead-out portion 21 has two lands R.sub.1, R.sub.2 where 
copper foil pieces are exposed which connect to the copper foil pattern P 
extending substantially in a zigzag manner. Each land R.sub.1, R.sub.2 is 
connected by soldering to a power supply cord 28 connecting to a power 
source battery. The soldered connections are denoted by reference numeral 
23. Two pins 22, 22 (see FIG. 5) are formed on the inner piece 12, in a 
position corresponding to the lead-out portion 21 of the FPC heater 20. By 
engaging the pins 22, 22 with holes 20a, 20a formed in the lead-out 
portion 21 of the FPC heater 20, the FPC heater 20 can be precisely 
positioned with respect to the inner piece 12. 
Formed on the inside end of the inner piece 12 is a cylindrical collar 13 
that has a cord placement groove 14 formed on its outer peripheral face. 
The power supply cord 28 soldered to the FPC heater 20 is laid in the 
groove 14, turning along the collar 13 until it passes under a cord 
support 13a formed integrally with the collar 13. Then the power supply 
cord 28 is led radially out of the collar 13. 
Since the power supply cord 28, embedded inside the handgrip body 10, turns 
along the collar 13 of the inner piece 12 and then exits from the handgrip 
body 10, the cord course length between the soldered connections 23 and 
the cord exit portion of the handgrip body 10 is considerably increased, 
correspondingly increasing the force that acts on the length of the power 
supply cord 28 embedded in the handgrip body 10 to tightly retain the cord 
28 to the handgrip body 10. More specifically, although the throttle 
operation of turning the handgrip body 10 causes a pulling force on the 
power supply cord 28 extending out of the handgrip body 10, this pulling 
force is withstood by the retaining force acting on the length of the 
power supply cord 28 embedded in the handgrip body 10 and, therefore, not 
transmitted to the soldered connections 23 to the FPC heater 20. 
In addition, at the cord exit, the power supply cord 28 is substantially 
bent back over the cord support 13a, which is harder than rubber, that is, 
of a greater stiffness than rubber. Thereby, the pulling force acting on 
the power supply cord 28 is borne by the cord support 13a before being 
transmitted to the length of the cord 28 embedded in the handgrip body 10, 
so that a reduced pulling force is transmitted to the length of the cord 
28 embedded in the handgrip body 10. 
A second embodiment of the invention will be described with reference to 
FIGS. 8-11. FIG. 8 shows a longitudinal sectional view of a left-side 
handgrip with a built-in heater according to the second embodiment. FIG. 9 
shows an exploded perspective view of an inner piece and an FPC heater 
constituting the left hand-side handgrip with a built-in heater. FIGS. 10, 
11 are transverse sectional views of the handgrip taken along lines X--X, 
XI--XI of FIG. 8, respectively. 
Referring to FIGS. 8-11, embedded in a cylindrical handgrip body 10A is an 
inner piece 12 exactly the same as that used in the right-side handgrip 
according to the first embodiment. The inner piece 12 is covered with a 
cover rubber layer 16. The amount of protrusion of a rubber layer 17 (17c, 
17d) from the inner peripheral face of the inner piece 12, the rubber 
layer filling in grooves 15a, 15b formed in the inner peripheral face of 
the inner piece 12, and the inside diameter of the inner peripheral face 
of the cylindrical handgrip body 10A are determined such that the handgrip 
body 10A can be fitted over a handle bar pipe 40. 
An FPC heater 20 of the left-side handgrip differs from that of the 
right-side handgrip in the direction of connection to a power supply cord 
28 (see FIG. 9), but other constructions, such as the disposed position of 
the FPC heater or the cord exit position, are substantially the same as 
those of the right-side handgrip. 
The other constructions or components of the handgrip body 10A are 
substantially the same as those of the first embodiment (right-side 
handgrip), and they are denoted by the same reference characters in the 
drawings and will not be described again. 
When the handgrip body according to the first and second embodiments is 
mounted on a handle bar pipe 40 as shown in FIG. 12, the power supply cord 
28 extends out of the handgrip body, downward from the handle bar pipe 40 
as indicated by the ghost lines. However, the power supply cord 28 may be 
led out upward from the handle bar pipe 40 as indicated by the solid lines 
in FIG. 12, by connecting the cord 28 to the FPC heater 20 in the 
direction opposite to the connecting direction according to the first or 
second embodiment. Thus, the power supply cord exit direction can be 
selected for individual vehicles. 
Although the inner piece 12 reinforcing the FPC heater 20 has a 
semi-cylindrical shape and the side wall portion of the handgrip body 10 
opposite the semi-cylindrical inner piece 12 is formed solely of the 
rubber layer according to the above embodiments, another semi-cylindrical 
inner piece may be disposed opposite to the semi-cylindrical inner piece 
12 so that the two inner pieces form a cylindrical shape. If the FPC 
heater extends over substantially the entire circumference of the 
cylindrical inner piece assembly, the whole handgrip body can be uniformly 
heated. 
Although the above embodiments have been described in conjunction with the 
FPC heater embedded in the handgrip body, the heater embedded in the 
handgrip body is not limited to the FPC heater. Other types of sheet-like 
heaters comprising nickel-base alloy wires and the like may also be 
employed. 
As apparent from the above description, the handgrips according to the 
above embodiments ensure reliable connection between the power supply cord 
and the sheet-like heater by a simple construction where the length of the 
power supply cord embedded in the handgrip body turns around the handle 
bar pipe by at least a half turn and another simple construction where the 
cord support of a high stiffness is provided in the cord exit portion of 
the handgrip body, for bearing the pulling forces that act on the power 
supply cord. Thus the embodiments require no size increase of the cord 
exit portion and facilitate smooth operation of switches or the like 
disposed near the handgrip. 
While the present invention has been described with reference to what are 
presently considered to be preferred embodiments thereof, it is to be 
understood that the invention is not limited to the disclosed embodiments. 
To the contrary, the invention is intended to cover various modifications 
and equivalent arrangements included within the spirit and scope of the 
appended claims.