Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Heat Exchanger For Motor Vehicle Exhaust
NAMES) OF INVENTOR(S):
Easton Bennett
FIELD OF THE INVENTION
The present invention relates to a heat exchanger for a
motor vehicle exhaust
BACKGROUND OF THE INVENTION
In Canadian Patent Application No. 2,185,076 (U. S. Patent
5,799,632) Easton Bennett disclosed a novel heat exchanger
configuration for a motor vehicle exhaust. This heat exchanger
had an exhaust pipe with a flow passage formed of a coil of
tubing. The exchange medium flows through the coil as hot
exhaust gases flow through the flow passage in the centre of
the coil.
In Canadian Patent Application No. 2,247,759 (U. S. Patent
Application No. 09/158,711) Easton Bennett disclosed an
improvement to the novel heat exchanger configuration. This
heat exchanger had the coil of tubing with the central flow
passage positioned in a larger housing, thereby forming an
annular flow down the outside of the coil of tubing, in
addition to the central flow passage. This configuration
proved to be even more efficient for heat transfer.
In some applications, however, there is a concern that the
heat exchanger will work too well and the coolant used as
exchange medium will become over heated.
SU1~IARY OF THE INVENTION
What is required is an alternative configuration of heat
exchanger for a motor vehicle exhaust.
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According to the present invention there is provided a
heat exchanger for a motor vehicle exhaust which includes a
tubular body having a first end, a second end, a peripheral
sidewall, and at least two flow passages that extend between
the first end and the second end. The at least two flow
passages include at least one heat exchange fluid flow passage
and at least one bypass fluid flow passage. A heat exchange
coil is positioned in the at least one heat exchange fluid flow
passage. The heat exchange coil has an inlet and an outlet
extending through the sidewall of the tubular body. A valve
is provided for selecting between the at least one heat
exchange fluid flow passage and the at least one bypass fluid
flow passage.
The heat exchanger, as described above, has a normal
operating mode in which all exhaust gases are diverted through
the heat exchange fluid flow passage to effect a heat exchange
with fluid flowing through the heat exchange coil. However,
when such a heat exchange is not desired, the valve is
repositioned to divert all exhaust gases through the bypass
fluid flow passage. It is also possible to put the valve in
an intermediate position to have only a portion of the exhaust
gases flow through the heat exchanger flow passage, as will
hereinafter be further described.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a top plan view, in section, of a heat
exchanger for a motor vehicle exhaust constructed in accordance
with the teachings of the present invention, with a valve
positioned in a heat exchanger mode.
FIGURE 2 is a top plan view, in section, of the heat
exchanger for a motor vehicle illustrated in FIGURE l, with the
valve positioned in a heat bypass mode.
FIGURE 3 is a top plan view, in section, of the heat
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exchanger for a motor vehicle illustrated in FIGURE l, with the
valve positioned in an intermediate mode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a heat exchanger for a motor
vehicle exhaust generally identified by reference numeral 100,
will now be described with reference to FIGURES 1 through 3.
Referring to FIGURE 1 through 3, heat exchanger for a
motor vehicle exhaust 100 includes a tubular body 102 having
a first end 104, a second end 106, a peripheral sidewall 108,
a heat exchange flow passage 110 and a bypass flow passage 112.
Each of heat exchange flow passage 110 and bypass flow passage
112 extends between first end 104 and second end 106. A dual
wall 114 that has an insulating air flow cavity 116 is
positioned between heat exchange fluid flow passage 110 and
bypass fluid flow passage 112. A heat exchange coil 118 is
positioned in heat exchange fluid flow passage 110. Heat
exchange coil 118 has an inlet 120 and an outlet 122 extending
through sidewall 108 of tubular body 102.
A pivotally movable valve member 124 is provided for
selecting a path of fluid flow. Referring to FIGURE 1, when
valve member 124 is in a first limiting position, fluid flows
through heat exchange fluid flow passage 110. Referring to
FIGURE 2, when valve member 124 is in a second limiting
position, fluid flows through bypass fluid flow passage 112.
Referring to FIGURE 3, when valve member 124 is in an
intermediate position, fluid flow is divided between heat
exchange fluid flow passage 110 and bypass fluid flow passage
112.
The use and operation of heat exchanger 100 will now be
described with reference to FIGURES 1 through 3. Heat
exchanger 100 is designed to be used when one wishes to raise
the temperature of automotive fluids or decrease the
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temperature of hot exhaust gases. This is accomplished when
valve member 124 is positioned as illustrated in FIGURE 1. In
cold weather conditions, it is advantageous to preheat fluids
used in the in car heater or engine oil. Hot exhaust gases
from the exhaust system provide a ready source of heat for this
purpose. The automotive fluid to be preheated is circulated
through heat exchange coil 118. In hot weather conditions, the
heat generated by exhaust gases is sometimes so extreme that
it fatigues and causes failure of some components. In such
circumstances it is advantageous to draw heat away from the hot
exhaust gases. Heat exchange coil 118 is used to circulate
fluids which draw heat from the hot exhaust gases. When
conditions change it may be necessary to stop further heat
exchange from occurring or quantitatively reduce the heat
exchange. To prevent the heat exchange from occurring, valve
member 124 is placed in the position illustrated in FIGURE 2.
To reduce the magnitude of the heat exchange, valve member 124
is placed in the position illustrated in FIGURE 3.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
