FIELD OF INVENTION;
This invention relates to a brake or fuel pipe for use in vehicles.
BACKGROUND;
Brake systems are integral part of any vehicle whether its a passenger car or commercial vehicle. Brake system works fundamentally on use of hydraulic pressure to stop front & rear wheels of the vehicle in a manner best suited from the point of overall vehicle design. Since Brake System works on hydraulic force, it requires transfer of brake fluid from the brake oil reservoir to various cylinders fitted on front & rear wheel. Transfer of this fluid takes place through brake pipes and hoses.
Brake Pipes are made from Copper Coated Mild Steel Strip through brazing process of different shapes and sizes. In the current case we have Brake Pipe of following type on which this technical innovation is successfully tried out & found OK.
Presently brake pipes are normally made of mild steel (fig.l). In order to protect the brake
pipe (4) from salty environment and to make it further corrosion resistant, it has a coating of
Zinc over it. However, in practice it has been found that such a coating is not sufficient to
make it durable & thereby requirement of additional layer of protective sleeve is required.
Thus, a heat shrink sleeve ( 5 ) on top of brake pipe to ensure that the bare portion of the
pipe does not come in contact with salty/moisturous environmental conditions and corrosion
does not take place.
Yet another advantage is that because of abrasion resistant properties of heat shrink sleeve,
it protects brake pipe against any sudden hits from small stones or foreign body. Such
sleeves were of a substantial length and were imported. Normally, such sleeves had a
length of 1700 mm, which substantially contributed to the end cost of the brake systems.
OBJECTS OF THE INVENTION;
An object of this invention is to propose an improved pipe system for use in a vehicle.
Another object of this invention is to propose an improved brake or fuel pipe system for
use in a vehicle.
Still another object of this invention is to propose an improved brake or fuel pipe system
for use in a vehicle which is cost effective.
Yet another object of this invention is to propose an improved brake or fuel pipe system
for use in a vehicle which is durable and has the required physical properties.
A further object of this invention is to propose an improved brake or fuel pipe system for use in a vehicle which prevents, the ingress of water.
DESCRIPTION OF THE INVENTION
According to this invention there is provided a pipe system such as a brake fluid or fuel pipe for use in a vehicle comprising a known metallic tube and having a plastic sleeve, a heat shrink cap at either end of said sleeve and embracing said pipe.
Most materials have the natural tendency to expanding under the influence of heat. However, the heat shrink sleeve (HSS) has the property of contracting on heat application. The same property can be defined through Equation 1.
(Equation Removed) Equation 1
whereas
df(HSS) - Final internal diameter of HSS
di(HSS) - Initial internal diameter of HSS
a HSS - Linear thermal expansion coefficient of HSS
AT-Change in temperature
Thus as apparent from the above equation, the inner diameter of heat shrink tube reduces the temperature increases, such a property is employed in the present invention. DESCRIPTION OF FIGURES; In the accompanying drawings:-
Fig. 1: Shows the brake pipe and fuel pipe known in the art. Fig.2: Shows the brake pipe and fuel pipe of present invention. DESCRIPTION WITH REFERENCE TO DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings.
Referring to Fig.2, the pipe system comprises the brake fluid or fuel metallic pipe 1 and as known in the art. By way of example only, metallic pipe 1 is an electrogalvanised tube. In the known art, a heat shrink sleeve of a length of, for example, 1700 mm was provided with pipe 1. The heat shrink sleeve did have advantages, and as apparent from equation 1. However, the heat shrink sleeve was attended with the distinct advantage of substantial costs, which is now avoided by the present invention.
In accordance with the present, a heat shrink cap 2 is provided on metallic pipe 1. Heat shrink cap 2 may be made of the same material as the heat shrink sleeve of the known art. However, the heat shrink cap 2 has an overlap portion 2a and a non overlaps portion 2b to hold a plastic sleeve 3. The plastic sleeve 3 is, for example, a polyvinyl chloride sleeve which is substantially cheaper than the heat shrink sleeve, and whereby the costs are substantially reduced. Reference is now made to numerical values only to exemplifying the teaching of the invention, but not to be taken in a restrictive manner.
In the present invention, a heat shrink cap 2 of 30mm length each is provided on both sides of sleeve 3. Out of 30mm length, 15mm length is overlap on PVC Sleeves & rest 15mm length on bare portion of the tube. As PVC Sleeve 3 is available at very reasonable price, it also meets all the physical properties which HSS of the known art. Table 1 evaluates all the properties of both HSS & PVC taken for this proposal:-
(Table Removed)
TABLE 1
Advantage of this technology are as under:-
A material saving of length 1640mm of HSS so it provides cost effective solution.
The possibility of water/ moisture ingress is taken care by providing sealing at two the ends.
Abrasion resistant properties are taken care be using PVC sleeve which is relatively cheaper & locally available and having same physical properties w.r.t HSS as explained in Table 1
This HSS joint on either side on Brake pipe can be split into two parts.
a) Nonoverlap portion - Length 15mm
b) Overlap portion - Length 15
In the case of non-overlap portion 2b of cap 2 HSS will contract under the application of
heat as explained in Equation 1. However, a concern remains for PVC Sleeve 3. As PVC
has the property of expanding under Heat, the properties of PVC is defined in Equation 2 (Equation Removed) Equation 2
whereas
dfflPVC) - Final external diameter of PVC
di(PVC) - Initial external diameter of PVC
oPVC - Linear thermal expansion coefficient of PVC
AT-Change in temperature
Cap 2 has a step construction. This can be explained because in non-overlap portion 2b
outer diameter of HSS is 6.76mm and at overlap portion of HSS & PVC diameter of HSS
is 8.76mm .
In the case of overlap portion, cap 2 has tendency to contract whereas PVC sleeves will
expand but the net effect woujd tte*that HSS cap 2 would contract as explained in Table 2. (TableRemoved)TABLE 2

CLAIMS:
1. A pipe system such as a brake fluid or fuel pipe for use in a vehicle comprising a
known metallic tube and having a plastic sleeve, a heat shrink cap at either end of said sleeve and embracing said pipe.
2. A pipe system such as a brake fluid or fuel pipe for use in a vehicle as claimed in
claim 1 wherein the heat shrink cap has a linear thermal expansion coefficient
different to that of said sleeve.
3. A pipe system in claim 1 wherein said sleeve has a stepped construction.
4. A pipe system in claim 1 wherein said sleeve is made of polyvinyl chloride.
5. A pipe system such a brake fluid or fuel pipe for use in a vehicle substantially as
herein described and illustrated.