U.S. patent application number 14/549181 was filed with the patent office on 2015-03-19 for heating-medium heating unit and vehicle air conditioner using the same.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Tomoyasu Adachi, Naoto Kunieda, Shiro Matsubara, Nobuya Nakagawa.
Application Number | 20150076133 14/549181 |
Document ID | / |
Family ID | 44798579 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150076133 |
Kind Code |
A1 |
Adachi; Tomoyasu ; et
al. |
March 19, 2015 |
HEATING-MEDIUM HEATING UNIT AND VEHICLE AIR CONDITIONER USING THE
SAME
Abstract
In a heating-medium heating unit equipped with a first
heating-medium circulation box and a second heating-medium
circulation box which are in close contact with both surfaces of a
PTC heater, in which heating-medium circulation passages are formed
in the interior, and which are joined to each other in a
liquidtight manner, wherein joining surfaces are sealed with liquid
gaskets, the heating-medium circulation passages are provided with
joining-surface cooling channels that cool the joining surface
which is sealed with a liquid gasket and on which the heat from the
PTC heater acts. The joining-surface cooling channels are provided
at positions closer to the joining surface than to the PTC
heater.
Inventors: |
Adachi; Tomoyasu; (Tokyo,
JP) ; Nakagawa; Nobuya; (Tokyo, JP) ;
Matsubara; Shiro; (Tokyo, JP) ; Kunieda; Naoto;
(Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES, LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
44798579 |
Appl. No.: |
14/549181 |
Filed: |
November 20, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13499994 |
Apr 3, 2012 |
|
|
|
PCT/JP2011/058417 |
Apr 1, 2011 |
|
|
|
14549181 |
|
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|
|
Current U.S.
Class: |
219/202 ;
219/504 |
Current CPC
Class: |
F24H 1/009 20130101;
F24H 1/121 20130101; B60H 2001/2268 20130101; F24H 2250/04
20130101; F24H 9/1827 20130101; F24H 3/085 20130101; B60H 1/2221
20130101; B60H 2001/2265 20130101 |
Class at
Publication: |
219/202 ;
219/504 |
International
Class: |
F24H 9/18 20060101
F24H009/18; B60H 1/22 20060101 B60H001/22; F24H 1/12 20060101
F24H001/12; F24H 1/00 20060101 F24H001/00; F24H 3/08 20060101
F24H003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2010 |
JP |
2010-093294 |
Claims
1. A heating-medium heating unit, comprising: a flat PTC heater; a
first heating-medium circulation box in which a plurality of box
components are stacked one on another, which is in close contact
with one surface of the PTC heater, and in which a heating-medium
circulation passage is formed in the interior; and a second
heating-medium circulation box in which a plurality of box
components are similarly stacked on one another, which is in close
contact with the other surface of the PTC heater, in which a
heating-medium circulation passage is formed in the interior, and
which is joined to the first heating-medium circulation box in a
liquidtight manner, wherein a heating medium that circulates
through the heating-medium circulation passages in the first and
second heating-medium circulation boxes is heated by heat radiated
from both surfaces of the PTC heater, wherein PTC modules that
constitute the PTC heater are disposed in a plurality of rows along
the channel direction of the heating-medium circulation passages,
the plurality of PTC modules have different widths, and ON/OFF
states of the PTC modules can be individually controlled.
2. A vehicle air conditioner including a blower that circulates
outside air or vehicle interior air, a cooler provided downstream
of the blower, and a radiator provided downstream of the cooler,
wherein a heating medium heated by the heating-medium heating unit
according to claim 1 can circulate through the radiator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/499,994 filed on Apr. 3, 2012, which is a National Stage
Application of PCT/JP2011/058417 filed on Apr. 1, 2011, which is
based on and claims the benefit of priority from Japanese Patent
Application No. 2010-093294, filed Apr. 14, 2010, which are hereby
incorporated by reference in their entirety.
TECHNICAL FIELD
[0002] The present invention relates to a heating-medium heating
unit that heats a heating medium using a positive temperature
coefficient (PTC) heater, and to a vehicle air conditioner using
the same.
BACKGROUND ART
[0003] One known heating-medium heating unit for heating a medium
to be heated uses a PTC heater that uses a positive temperature
coefficient thermistor device (PTC device) as a heating element.
The PTC heater has a positive temperature thermistor coefficient
and thus shows an increasing value of resistance as the temperature
increases, which allows the current consumption to be controlled
and the increase in temperature to be slowed, and thereafter, the
current consumption and the temperature of the heat generating
portion reach a saturation region and are stabilized; that is, the
PTC heater has a self temperature control characteristic.
[0004] The PTC heater has the characteristic that the current
consumption is reduced as the temperature of the heater increases,
and thereafter when the temperature reaches a saturation region of
a fixed temperature, the current consumption stabilizes at a low
value. The use of this characteristic provides advantages in that
current consumption can be reduced and an abnormal increase in the
temperature of the heat generating portion can be prevented.
[0005] Therefore, PTC heaters are used in many technical fields.
Also in the field of air conditioning, as disclosed in PTL 1, for
example, in a hybrid-vehicle air conditioner, a heating-medium
heating unit in which the PTC heater is applied to a heating unit
for heating a heating medium (here, engine coolant) to be supplied
to a radiator for heating air when the engine is stopped has been
proposed.
[0006] In this heating-medium heating unit, two heating-medium
circulation boxes are joined to each other via an O-ring in a
liquidtight manner, and a flat PTC heater is closely interposed
between the two heating-medium circulation boxes. The
heating-medium circulation boxes are each configured such that a
plurality of box components are joined via O-rings in a liquidtight
manner, and the heating-medium circulation boxes each have therein
a circulation path through which engine coolant, which is a heating
medium, circulates.
[0007] The heating-medium circulation boxes each have a flat
radiating surface in close contact with the PTC heater, and a
grooved level-difference portion is formed between the flat surface
and a joining surface formed on the outer periphery of each
heating-medium circulation box (box component) (see FIG. 5 in PTL
1).
[0008] This is for the purpose of preventing the O-rings from being
overheated by increasing the length of the heat transmission path
from the PTC heater to the foregoing O-rings to prevent the O-rings
interposed between the joining surfaces from deteriorating in
quality due to high heat generated from the PTC heater, which would
cause liquid leaks. The level-difference portion is provided with
wiring members extending from the PTC heater.
CITATION LIST
Patent Literature
[0009] {PTL 1} Japanese Unexamined Patent Application, Publication
No. 2008-56044
SUMMARY OF INVENTION
Technical Problem
[0010] However, since the heating-medium heating unit described in
PTL 1 has a configuration in which a flat PTC heater is closely
interposed between a pair of heating-medium circulation boxes
configured such that a plurality of box components are joined via
O-rings in a liquidtight manner, as described above, a large number
of O-rings are needed, thus increasing the number of components,
and moreover, complicating the assembly work, and furthermore,
needing the carving of fitting grooves in which the O-rings are
fitted in the joining surfaces of the box components, which has
caused an increase in the manufacturing cost of the heating-medium
heating unit.
[0011] Furthermore, since level-difference portions, such as
grooves, are formed between the radiating surfaces in close contact
with the PTC heater and the joining surfaces formed on the outer
peripheries of the heating-medium circulation boxes (box
components), the number of man-hours for machining the box
components is large, which causes an increase in the manufacturing
cost of the heating-medium circulation boxes, and thus the entire
heating-medium heating unit.
[0012] Furthermore, since wiring members extending from the PTC
heater are disposed between the PTC heater and the outer
peripheries (joining surfaces) of the heating-medium circulation
boxes, the dimensions of the outer peripheries of the
heating-medium circulation boxes are significantly larger than the
area of the flat surface of the PTC heater, which also causes an
increase in the manufacturing cost of the heating-medium heating
unit.
[0013] The present invention has been made in consideration of such
circumstances, and an object thereof is to provide a heating-medium
heating unit which accommodates a PTC heater, in which the
manufacturing cost of heating-medium circulation boxes through
which a heating medium circulates is reduced, and in which leakage
of the heating medium from the heating-medium circulation boxes is
prevented so that the reliability can be enhanced, as well as a
vehicle air conditioner using the same.
Solution to Problem
[0014] To achieve the above object, the present invention provides
the following solutions.
[0015] A heating-medium heating unit according to a first aspect of
the present invention includes a flat PTC heater; a first
heating-medium circulation box in which a plurality of box
components are stacked one on another, which is in close contact
with one surface of the PTC heater, and in which a heating-medium
circulation passage is formed in the interior; and a second
heating-medium circulation box in which a plurality of box
components are similarly stacked on one another, which is in close
contact with the other surface of the PTC heater, in which a
heating-medium circulation passage is formed in the interior, and
which is joined to the first heating-medium circulation box in a
liquidtight manner, wherein a heating medium that circulates
through the heating-medium circulation passages in the first and
second heating-medium circulation boxes is heated by heat radiated
from both surfaces of the PTC heater, wherein at least one of a
joining surface between the box components that constitute the
first heating-medium circulation box and the second heating-medium
circulation box and a joining surface between the first
heating-medium circulation box and the second heating-medium
circulation box is sealed with a liquid gasket; and wherein the
heating-medium circulation passage of at least the first
heating-medium circulation box or the second heating-medium
circulation box is provided with a joining-surface cooling channel
that is sealed with the liquid gasket and that cools the joining
surface on which the heat from the PTC heater acts.
[0016] With the heating-medium heating unit, the heating-medium
heating unit can be assembled by sealing spaces between the
plurality of box components constituting the heating-medium heating
unit using only liquid gaskets. The two heating-medium circulation
boxes can also be assembled with the space therebetween being
sealed using only a liquid gasket. This can therefore eliminate a
large number of O-rings used in the related art, thus reducing the
number of components and assembly man-hours, and moreover, can
eliminate fitting grooves that are conventionally carved in the
individual joining surfaces of the box components to fit the
O-rings therein, thereby reducing the number of man-hours for
machining the box components, thus allowing the manufacturing cost
of the heating-medium circulation boxes to be reduced.
[0017] Moreover, since the liquid gaskets applied to the joining
surfaces can be protected from the heat from the PTC heater by
using the cooling channel provided in the heating-medium
circulation passage of at least the first heating-medium
circulation box or the second heating-medium circulation box, the
durability of the liquid gasket is enhanced, and thus leakage of
the heating medium from the joining surface can be prevented.
[0018] In the heating-medium heating unit according to the first
aspect of the present invention, preferably, the joining-surface
cooling channel is provided at a position closer to the joining
surface sealed with the liquid gasket than to the PTC heater. This
allows the liquid gasket applied to the joining surface to be
protected from the heat from the PTC heater more reliably.
[0019] In the heating-medium heating unit according to the first
aspect of the present invention, preferably, the joining surface is
provided with an outside sealing section that seals a space between
the heating-medium circulation passage and the outside and a board
sealing section that seals a space between the heating-medium
circulation passage and a portion communicating with a portion
accommodating a board for controlling the PTC heater, in which the
width of the board sealing section is larger than the width of the
outside sealing section. This can reliably prevent coolant leakage
to the control board while eliminating the O-ring so that the
manufacturing cost can be reduced, thereby enhancing the
reliability of the heating-medium heating unit.
[0020] In the heating-medium heating unit according to the first
aspect of the present invention, preferably, a radiating surface of
at least one of the first heating-medium circulation box and the
second heating-medium circulation box, the radiating surface being
in close contact with the PTC heater, and the joining surface
between the first heating-medium circulation box and the second
heating-medium circulation box are formed as a continuous flat
surface without a level-difference. This can remarkably simplify
machining of at least the first or second heating-medium
circulation box, thus reducing the manufacturing cost of the
heating-medium circulation box.
[0021] Furthermore, in the heating-medium heating unit according to
the first aspect of the present invention, preferably, the PTC
heater and the first and second heating-medium circulation boxes
are formed in a rectangular shape, and a wiring member of the PTC
heater extends from an end of the PTC heater in the longitudinal
direction. This can eliminate the wiring members of the PTC heater
interposed between the long side of the PTC heater and the long
side of the heating-medium circulation box, and hence the outer
peripheral dimensions of the heating-medium circulation box can be
brought close to the planar outside dimensions of the PTC heater,
and in addition, the heating-medium circulation box can be made
compact, and thus the manufacturing cost can be reduced.
[0022] In the heating-medium heating unit, preferably, PTC devices
that constitute the PTC heater are disposed in a plurality of rows
along the channel direction of the heating-medium circulation
passages, the plurality of PTC heaters have different widths, and
ON/OFF states of the PTC devices can be individually controlled.
With this configuration, the wiring members of the PTC heater can
be easily provided together at one end of the PTC heater in the
longitudinal direction, the amount of heat from the PTC heater can
be controlled with a simple configuration, and thus a reduction in
the manufacturing cost due to the size reduction of the
heating-medium heating unit and enhanced reliability can be
achieved.
[0023] Furthermore, a vehicle air conditioner according to a second
aspect of the present invention includes a blower that circulates
outside air or vehicle interior air, a cooler provided downstream
of the blower, and a radiator provided downstream of the cooler,
wherein a heating medium heated by the heating-medium heating unit
according to the first aspect can circulate through the radiator.
This can enhance the reliability while reducing the manufacturing
cost of the heating-medium heating unit.
Advantageous Effects of Invention
[0024] Thus, with the heating-medium heating unit according to the
present invention and the vehicle air conditioner using the same,
it is possible to reduce the manufacturing cost of the
heating-medium circulation box which accommodates a PTC heater and
through which a heating medium circulates, and to prevent leakage
of the heating medium from the heating-medium circulation box, and
hence the reliability can be enhanced.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is a schematic configuration diagram of a vehicle air
conditioner according to an embodiment of the present
invention.
[0026] FIG. 2 is a perspective view of a heating-medium heating
unit according to an embodiment of the present invention.
[0027] FIG. 3 is an exploded perspective view of the heating-medium
heating unit according to the embodiment of the present
invention.
[0028] FIG. 4 is a vertical cross-sectional view taken along line
IV-IV in FIG. 2.
[0029] FIG. 5 is a vertical cross-sectional view taken along line
V-V in FIG. 2.
[0030] FIG. 6 is a perspective view of a board-accommodating box
shown in FIG. 3, turned upside down.
[0031] FIG. 7 is a bottom view of an upper heating-medium
circulation box taken along arrows VII-VII in FIG. 4.
[0032] FIG. 8 is a top view of a lower heating-medium circulation
box taken along arrows VIII-VIII in FIG. 4.
[0033] FIG. 9 is an enlarged diagram of part IX in FIG. 4.
DESCRIPTION OF EMBODIMENT
[0034] An embodiment of the present invention will be described
hereinbelow using FIGS. 1 to 9.
[0035] FIG. 1 shows a schematic configuration diagram of a vehicle
air conditioner 1 according to this embodiment. The vehicle air
conditioner 1 is, for example, a hybrid-vehicle air conditioner and
is equipped with a casing 3 forming an air channel 2 through which
outside air or vehicle interior air is taken in, controls the
temperature thereof, and guides it into the vehicle interior.
[0036] The casing 3 accommodates, in sequence from the upstream
side to the downstream side of the air channel 2, a blower 4 that
takes in outside air or vehicle interior air, increases the
pressure thereof, and blows it downstream; a cooler 5 that cools
the air blown by the blower 4; a radiator 6 that heats the air
cooled by passing through the cooler 5; and an air mix damper 7
that adjusts the ratio of the amount of air passing through the
radiator 6 to the amount of flowing air bypassing the radiator 6 to
control the temperature of the air mixed downstream thereof.
[0037] The downstream side of the casing 3 is connected to a
plurality of vents (not shown) through which the
temperature-controlled air is blown out into the vehicle interior
via a blowing-mode switching damper and a duct (not shown). The
cooler 5 constitutes a refrigerant circuit together with a
compressor, a condenser, and an expansion valve (not shown) and
cools air passing therethrough by evaporating a refrigerant that is
adiabatically expanded at the expansion valve.
[0038] The radiator 6 constitutes a heating-medium circulating
circuit 11 together with a tank 8, a pump 9, an engine (not shown),
and a heating-medium heating unit 10 according to the present
invention. Engine coolant of a hybrid vehicle is used as a heating
medium flowing through the heating-medium circulating circuit 11.
The heating-medium circulating circuit 11 heats the air passing
through the radiator 6 in the casing 3 by heating the engine
coolant with the heating-medium heating unit 10 when the
temperature of the engine coolant, serving as the heating medium,
does not significantly increase, such as during hybrid driving, and
by circulating the heated engine coolant through the heating-medium
circulating circuit 11 with the pump 9.
[0039] FIG. 2 shows a perspective view of the heating-medium
heating unit 10; FIG. 3 shows an exploded perspective view of the
heating-medium heating unit 10; and FIGS. 4 and 5 show vertical
cross-sectional views of the heating-medium heating unit 10.
[0040] The heating-medium heating unit 10 is equipped with a first
heating-medium circulation box A configured like a casing such that
a plurality of box components 20, 21, and 30 are stacked one on
another; a second heating-medium circulation box B which is
configured like a casing such that a plurality of box components 50
and 51 are similarly stacked one on another and which is joined to
the lower surface of the first heating-medium circulation box A in
a liquidtight manner; and a PTC heater 40 sandwiched between the
first and second heating-medium circulation boxes A and B.
[0041] The first heating-medium circulation box A is formed such
that the rectangular board-accommodating box 20, to the upper
surface of which the cap 21 is joined, and the upper heating-medium
circulation box 30 having the same rectangular shape as the
board-accommodating box 20 are joined together in a liquidtight
manner. The second heating-medium circulation box B is formed of
the lower heating-medium circulation box 50 having the same
rectangular shape as the upper heating-medium circulation box 30
and the cap 51, which is joined to the lower surface of the lower
heating-medium circulation box 50 in a liquidtight manner. The
first heating-medium circulation box A, the second heating-medium
circulation box B, and the other box components 20, 21, 30, 50, and
51 are tightened together with a plurality of bolts 58 to form a
single unit, as shown in FIG. 2 and FIG. 4.
[0042] The PTC heater 40 has a rectangular, flat shape smaller than
those of the upper heating-medium circulation box 30 and the lower
heating-medium circulation box 50, the upper surface of the PTC
heater 40 is in close contact with a flat radiating surface 38
formed at the lower surface of the upper heating-medium circulation
box 30, and the lower surface of the PTC heater 40 is in close
contact with a flat radiating surface 56 formed on the upper
surface of the lower heating-medium circulation box 50, as will be
described later in detail.
[0043] The board-accommodating box 20 is a rectangular half casing
which is formed of a thermally conducting material, such as an
aluminum alloy, whose upper surface is tightly sealed by the cap
21, and whose interior serves as a board-accommodating space S, in
which a control board 22 (see FIGS. 3 and 4) that controls the PTC
heater 40 is accommodated. The control board 22 incorporates heat
generating components and control circuits, such as field effect
transistors (FETs) 23, and is supplied with a high voltage of 300 V
for driving the PTC heater 40 and a low voltage of 12 V for
control.
[0044] The control board 22 is fixedly disposed on supporting
portions 24 projecting from the bottom surface of the
board-accommodating box 20 by being fastened with screws 25a at the
four corners. The heat generating components, such as the FETs 23,
are disposed on the lower surface side of the control board 22 and
are fastened and fixed with screws 25b to the upper surface of a
cooling portion 26 provided on the bottom surface of the
board-accommodating box 20 that is in contact therewith via an
insulating layer (not shown) therebetween. The heat generating
components, such as the FETs 23, and the cooling portion 26 are
disposed in the vicinity of the inlet of heating-medium circulation
passages (circulation paths 33), described later, provided in the
upper heating-medium circulation box 30, to enhance the cooling
effect on the heat generating components.
[0045] Wire insertion holes 27 are formed at one end face of the
board-accommodating box 20 (see FIGS. 3 and 6), through which
wiring members 40a (see FIG. 2) connected to the control board 22
are passed. Wire routing holes 28 (see FIG. 6) through which a
harness connecting the control board 22 and the PTC heater 40
passes are formed in the lower surface at one end of the
board-accommodating box 20. A harness insertion hole 29 (see FIG.
3) is formed at the other end of the board-accommodating box 20,
through which an electrical harness 22a (see FIG. 2) connecting to
the control board 22 passes.
[0046] FIGS. 3 to 5 and FIG. 7 illustrate the heating-medium
circulation passages in the upper heating-medium circulation box
30. The upper heating-medium circulation box 30 is a rectangular
half casing which is formed of a thermally conducting material,
such as an aluminum alloy, and whose upper surface is provided with
a pair of inlet header 31 and outlet header 32 formed at both ends
and parallel grooved circulation paths 33, which are formed between
the inlet header 31 and the outlet header 32 and are separated by a
large number of fins 33a. The upper surfaces of the inlet header
31, the outlet header 32, and the circulation paths 33 are sealed
off by the bottom surface of the board-accommodating box 20 in a
liquidtight manner (see FIGS. 4 and 5).
[0047] Thus, an engine-coolant circulation passage through which
the engine coolant flowing into the inlet header 31 is distributed
to the large number of circulation paths 33 so as to flow
simultaneously in parallel in the circulation paths 33 toward the
outlet header 32 is formed between the board-accommodating box 20
and the upper heating-medium circulation box 30. The engine coolant
flowing in the circulation paths 33 does not flow directly into the
outlet header 32 but flows into a circulation opening 35 (see FIG.
7), described later, formed in the lower surface of the upper
heating-medium circulation box 30. The above-described cooling
portion 26 formed on the bottom surface of the board-accommodating
box 20 is cooled by the engine coolant circulating in the
circulation paths 33, described above, and thus constitutes a
cooling structure for the control board 22.
[0048] The inlet header 31 is provided with an engine-coolant
inflow portion 34, and the outlet header 32 is provided with the
circulation opening 35 connecting to the lower heating-medium
circulation box 50, a circulation opening 36 through which the
engine coolant flowing from the lower heating-medium circulation
box 50 is made to flow outwards, as will be described later, and an
engine-coolant outflow portion 37 communicating with the outside
via the circulation opening 36. The inflow portion 34 and the
outflow portion 37 are provided with respective union members 34a
and 37a (see FIGS. 2 and 5) that allow hose members constituting
the heating-medium circulating circuit 11 to be connected
thereto.
[0049] Furthermore, the lower surface of the upper heating-medium
circulation box 30 is provided with a wide depressed portion (see
FIGS. 4, 5 and 7) whose ceiling surface serves as the flat
radiating surface 38 that is in close contact with the upper
surface of the PTC heater 40. This depressed portion faces the back
surfaces of the circulation paths 33 through which the engine
coolant circulates and is formed such that the PTC heater 40 is
fitted therein. Wire insertion holes 39 (see FIG. 3) are formed at
the end of the upper surface of the upper heating-medium
circulation box 30 opposite to the circulation openings 35 and 36,
and the wire insertion holes 39 match the wire routing holes 28 of
the board-accommodating box 20.
[0050] FIGS. 3 to 5 and FIG. 8 illustrate heating-medium
circulation passages in the lower heating-medium circulation box
50. The lower heating-medium circulation box 50 is a rectangular
half casing which is constituted by a thermally conducting
material, such as an aluminum alloy, in which communication
openings 52 and 53 (see FIG. 8) are provided at one end thereof,
and the communication openings 52 and 53 match the circulation
openings 35 and 36 of the upper heating-medium circulation box 30,
respectively.
[0051] The lower surface of the lower heating-medium circulation
box 50 is provided with parallel grooved circulation paths 54 that
extend from the communication opening 52 toward the other end and
that make a U-turn at the other end to return to the communication
opening 53 and that are separated by a large number of fins 54a
(see FIG. 4). The supply channels and the return channels of the
U-shaped circulation paths 54 are separated by a partition wall 54b
(see FIG. 4) higher than the fins 54a. The lower surfaces of the
circulation paths 54 are tightly sealed by the cap 51, as described
above, and the cap 51 has a U-shaped shallow depressed portion 55
(see FIG. 3) that matches the shapes of the circulation paths 54
and the partition wall 54b.
[0052] Thus, a heating-medium circulation passage through which the
engine coolant flowing into the communication opening 52 is
distributed from the communication opening 52 to the large number
of circulation paths 54, circulates in the individual circulation
paths 54 simultaneously in parallel, and makes a U-turn at the
other end to reach the communication opening 53 is formed between
the lower heating-medium circulation box 50 and the cap 51.
[0053] The communication opening 52 of the lower heating-medium
circulation box 50 communicates with the circulation opening 35
provided in the outlet header 32 of the upper heating-medium
circulation box 30 so that the engine coolant flowing in the
circulation paths 33 of the upper heating-medium circulation box 30
flows therein. The communication opening 53 of the lower
heating-medium circulation box 50 communicates with the circulation
opening 36 provided in the outlet header 32 of the upper
heating-medium circulation box 30 to constitute a passage through
which the engine coolant flowing in the lower heating-medium
circulation box 50 is made to flow outwards from the circulation
opening 36 via the outflow portion 37.
[0054] The upper surface of the lower heating-medium circulation
box 50 serves as the radiating surface 56 (see FIGS. 3 to 5 and
FIG. 8) and holds the PTC heater 40 with the flat radiating surface
38 at the lower surface of the upper heating-medium circulation box
30 therebetween like a sandwich, so that the radiating surfaces 38
and 56 are in pressure-contact with compressive heat conducting
layers 44, to be described later, bonded to both surfaces of the
PTC heater 40.
[0055] FIGS. 3 and 4 and FIGS. 7 to 9 illustrate the configuration
of the PTC heater 40. The PTC heater 40 is rectangular in overall
shape. The PTC heater 40 is constituted by PTC devices 41a, 41b,
and 41c serving as heat-generating elements, disposed in, for
example, three rows, along the channel direction of the
heating-medium circulation passages (circulation paths 33 and
circulation paths 54). Of the three PTC devices 41a, 41b, and 41c,
the PTC devices 41a and 41c at both ends are set to be, for
example, twice as wide as the PTC device 41b at the center.
[0056] As shown in an enlarged cross-sectional view in FIG. 9, the
PTC devices 41a, 41b, and 41c each have a stacked structure in
which electrode plates 42, noncompressive insulating layers 43, and
the compressive heat conducting layers 44 are stacked in sequence.
The PTC devices 41a, 41b, and 41c are configured such that the
ON/OFF states thereof can be individually controlled by control
circuits incorporated in the control board 22.
[0057] The electrode plates 42 are for supplying electric power to
the PTC devices 41a, 41b, and 41c, are rectangular thin plates
similar to the PTC devices 41a, 41b, and 41c, and have electrical
conductivity and thermal conductivity. The noncompressive
insulating layers 43 are rectangular thin plates, are each
constituted by an insulating material, such as a polyamide film,
and have thermal conductivity. The noncompressive insulating layers
43 are 0.1 mm or less in thickness. This is for the purpose of
minimizing the thermal resistance between the PTC devices 41a, 41b,
and 41c and the electrode plates 42 and between the upper
heating-medium circulation box 30 (radiating surface 56) and the
lower heating-medium circulation box 50 (radiating surface 38)
provided at the outside thereof and for providing sufficient
electrical insulation.
[0058] Furthermore, the compressive heat conducting layers 44 are
rectangular sheet members having compressibility, which are
constituted by insulating sheets, such as silicone sheets and have
thermal conductivity. The compressive heat conducting layers 44
are, if constituted by silicone sheets, set to be about 0.4 mm to
2.0 mm in thickness to reduce the thermal resistance between the
PTC device 41 serving as a heat-generating element and the upper
heating-medium circulation box 30 (radiating surface 38) and the
lower heating-medium circulation box 50 (radiating surface 56). The
thickness of at least 0.4 mm or more ensures a compressing
function, allowing the upper heating-medium circulation box 30 and
the lower heating-medium circulation box 50 to be reliably brought
into close contact with the PTC heater 40 by using the
compressibility when the PTC heater 40 is mounted between the upper
heating-medium circulation box 30 and the lower heating-medium
circulation box 50, and allowing the mounting dimensional tolerance
to be absorbed.
[0059] Thus, as shown in FIGS. 4 and 5, the PTC heater 40 can heat
the engine coolant circulating in the upper heating-medium
circulation box 30 and the lower heating-medium circulation box 50
provided in close contact with both sides thereof by radiating the
heat from both sides.
[0060] The PTC heater 40 has wiring members 40b at one end thereof,
and the wiring members 40b are bent upwards at right angles to the
planar direction of the PTC heater 40 and are inserted into the
wire insertion holes 39 of the upper heating-medium circulation box
30 and the wire insertion routing holes 28 of the
board-accommodating box 20. The wiring members 40b are guided to
the control board 22, so that the cable-like wiring members 40a
(see FIG. 2) are drawn outwards from the control board 22 through
the wire insertion holes 27 of the board-accommodating box 20, as
described above. The wire insertion holes 27 are fitted with a
waterproof, dustproof wire cap 40c.
[0061] The heating-medium circulating circuit 11 is connected to
the inflow portion 34 of the upper heating-medium circulation box
30. Low-temperature engine coolant pumped from the pump 9 flows
through the inflow portion 34 into the inlet header 31 and is
distributed to the individual circulation paths 33 (see FIG. 3).
The engine coolant flowing through the circulation paths 33 toward
the outlet header 32 is heated and increased in temperature by the
PTC heater 40, joins before the outlet header 32, and flows into
the communication opening 52 of the lower heating-medium
circulation box 50 through the circulation opening 35.
[0062] The engine coolant diverges at the communication opening 52
into the individual circulation paths 54, flows as indicated by an
imaginary line F in FIG. 8 while being heated and increased in
temperature again by the PTC heater 40, makes a U-turn at the other
end, passes through the communication opening 53 and then the
circulation opening 36 of the upper heating-medium circulation box
30 and enters the outlet header 32, passes through the outflow
portion 37, and flows back to the heating-medium circulating
circuit 11. Thus, the engine coolant passing through the interior
of the heating-medium heating unit 10 flows along both surfaces of
the PTC heater 40 and circulates in the heating-medium circulating
circuit 11 while being heated by the heat from the PTC heater 40,
so that the temperature of the vehicle interior is controlled.
[0063] Since the PTC devices 41a, 41b, and 41c that constitute the
PTC heater 40 are configured such that the ON/OFF states can be
individually controlled by the control circuits incorporated in the
control board 22, the individual PTC devices 41a, 41b, and 41c are
independently turned ON and OFF by the control board 22 according
to the difference between the actual temperature of the engine
coolant flowing into the heating-medium heating unit 10 and a
necessary temperature (target temperature), and thus the heating
capability is controlled. This allows the engine coolant to flow
out while being heated and increased to a predetermined
temperature.
[0064] Next, the relevant part of the present invention will be
described. As shown in FIG. 4, the heating-medium heating unit 10
has a plurality of joining surfaces M1 to M4. Joining surfaces
between the first heating-medium circulation box A and the second
heating-medium circulation box B, that is, a joining surface M1
between the upper heating-medium circulation box 30 and the lower
heating-medium circulation box 50, joining surfaces M2 and M3
between the board-accommodating box 20 and the cap 21 and the upper
heating-medium circulation box 30 that constitute the first
heating-medium circulation box A, and a joining surface M4 between
the lower heating-medium circulation box 50 and the cap 51 that
constitute the second heating-medium circulation box B, are
configured to be sealed with liquid gaskets. Examples of the liquid
gaskets include a waterproof, heat-resistant silicone sealant that
becomes rubbery when it hardens.
[0065] Furthermore, the circulation paths 33 that serve as the
heating-medium circulation passages of the first heating-medium
circulation box A and the circulation paths 54 that serve as the
heating-medium circulation passages of the second heating-medium
circulation box B are provided with joining-surface cooling
channels C1 and C2, respectively. These joining-surface cooling
channels C1 and C2 are provided to particularly cool, of the
joining surfaces M1 to M4 sealed by the liquid gaskets, the
vicinity of the joining surface M1, on which a considerable amount
of the heat from the PTC heater 40 acts, thereby preventing the
liquid gasket applied to the joining surface M1 from being degraded
due to the heat.
[0066] The joining-surface cooling channel C1 constitutes, of the
plurality of circulation paths 33, one or two circulation paths
close to the joining surface M1, and the joining-surface cooling
channel C2 constitutes, of the plurality of circulation paths 54,
one or two circulation paths close to the joining surface M1. These
joining-surface cooling channels C1 and C2 are provided at
positions closer to the joining surface M1 than to the edge of the
PTC heater 40. Therefore, the heat from the PTC heater 40 is
subjected to heat exchange by the engine coolant that flows through
the joining-surface cooling channels C1 and C2 before being
transmitted to the joining surface M1, which makes the heat
difficult to be transmitted to the joining surface M1. Accordingly,
this allows the liquid gasket that seals the joining surface M1 to
be protected from the heat, thus enhancing the durability, which
prevents the heating medium from leaking through the joining
surface M1.
[0067] Of the joining surfaces M1 to M4, the joining surface M3
between the lower surface of the board-accommodating box 20 and the
upper surface of the upper heating-medium circulation box 30,
through which the wiring members 40b of the PTC heater 40 pass,
includes an outside sealing section M3a that seals a space between
the heating-medium circulation passages (circulation paths 33) and
the outside and a board sealing section M3b that seals a space
between the heating-medium circulation passages (circulation paths
33) and the wire routing holes 28, which are portions communicating
with the board-accommodating space S, as shown in FIG. 6, which
illustrates the shape of the lower surface of the
board-accommodating box 20. The width W2 of the board sealing
section M3b is set to be larger than the width W1 of the outside
sealing section M3a. For example, W1 is set at 5 mm, and W2 is set
at 8 mm.
[0068] As shown in FIG. 4, either one of the upper and lower
surfaces of the individual joining surfaces M1 to M4 are each
provided with a level-difference portion Mc along the inner
peripheral edge thereof. Forming the level-difference portions Mc
allows the liquid gasket to be maintained at a predetermined
thickness by the level-difference portion Mc and to be able to
harden without being subjected to a pressing force. If both
surfaces of the individual joining surfaces M1 to M4 were made flat
without the flat level-difference portion Mc, the liquid gaskets
applied therebetween would be completely pushed out from the range
of the joining surfaces when a pressing force is applied thereto,
thus posing a worry that sufficient sealability would not be
maintained. The height of the level-difference portion Mc may be
about 0.5 mm to 2.0 mm.
[0069] As shown in FIGS. 3, 4, and 8, for example, in the lower
heating-medium circulation box 50 constituting the second
heating-medium circulation box B, the radiating surface 56 in close
contact with the PTC heater 40 and the joining surface M1 between
it and the first heating-medium circulation box A are formed as a
continuous flat surface without a level-difference.
[0070] The heating-medium heating unit 10 according to this
embodiment is configured as described above. This heating-medium
heating unit 10 provides the following advantages.
[0071] First, since the joining surfaces M1 to M4 between the box
components 20, 21, 30, 50, and 51 that constitute the first
heating-medium circulation box A and the second heating-medium
circulation box B are configured to be sealed with the liquid
gaskets, the O-rings that are conventionally interposed between the
joining surfaces M1 to M4 can be eliminated. This can reduce the
number of components and the number of man-hours for assembling the
heating-medium heating unit 10, and moreover, can eliminate fitting
grooves that are conventionally carved in the individual joining
surfaces M1 to M4 to fit the O-rings therein, thereby reducing the
number of man-hours for machining the box components 20, 21, 30,
50, and 51, thus allowing the manufacturing cost of the
heating-medium circulation box 10 to be remarkably reduced.
[0072] Since the joining-surface cooling channels C1 and C2 are
provided in the heating-medium circulation passages (circulation
paths 33 and 54) of the first heating-medium circulation box A and
the second heating-medium circulation box B, of the four joining
surfaces M1 to M4 sealed with the liquid gaskets, the joining
surface M1 on which a considerable amount of the heat from the PTC
heater 40 acts can be cooled favorably. This can therefore prevent
the liquid gasket applied to the joining surface M1 from being
degraded due to heat, and realizes a sealing technique only with
the liquid gasket without using an O-ring, thus significantly
contributing to a reduction in the manufacturing cost of the
heating-medium heating unit 10.
[0073] Furthermore, since these joining-surface cooling channels C1
and C2 are provided at positions closer to the joining surface M1
than to the edge of the PTC heater 40, the liquid gasket applied to
the joining surface M1 can be more reliably protected from the heat
from the PTC heater 40. For the joining surfaces M3 and M4, since
the positions of the circulation paths 33 and 54 are closer to the
joining surfaces M3 and M4 than to the PTC heater 40, it is
difficult for the joining surfaces M3 and M4 to be affected by the
heat from the PTC heater 40.
[0074] The shapes of the joining-surface cooling channels C1 and C2
are not limited to those of this embodiment; they may be other
shapes. For example, in this embodiment, although the depths and
widths of the joining-surface cooling channels C1 and C2 are equal
to or smaller than those of the adjacent circulation paths 33 and
54, the depths and widths may be larger than those of the
circulation paths 33 and 54 so that much more engine coolant will
flow through a portion closer to the joining surface M1, thereby
further enhancing the cooling performance of the joining surface
M1.
[0075] Furthermore, in this heating-medium heating unit 10, of the
joining surfaces M1 to M4, the joining surface M3 through which the
wiring members 40b of the PTC heater 40 pass is configured such
that the width W2 of the board sealing section M3b is set to be
larger than the width W1 of the outside sealing section Mia;
therefore, while the O-ring on the joining surface M3 is eliminated
so that the manufacturing cost can be reduced, coolant leakage to
the board-accommodating space S in which the control board 22 is
accommodated can be reliably prevented, and hence the reliability
of the heating-medium heating unit 10 can be enhanced.
[0076] Furthermore, in this heating-medium heating unit 10, since
the radiating surface 56 of the lower heating-medium circulation
box 50 that constitutes the second heating-medium circulation box B
and the joining surface M1 to the first heating-medium circulation
box A are formed as a continuous flat surface without a
level-difference, the upper surface of the lower heating-medium
circulation box 50 can be made completely flat, thereby remarkably
facilitating processing of the lower heating-medium circulation box
50, thus reducing the manufacturing cost of the heating-medium
circulation box 10.
[0077] Furthermore, in this heating-medium heating unit 10, since
the PTC heater 40, the first heating-medium circulation box A, and
the second heating-medium circulation box B are formed in a
rectangular shape, and the wiring members 40b of the PTC heater 40
are extended together from the end of the PTC heater 40 in the
longitudinal direction, the wiring members of the PTC heater 40 are
not interposed between the long side of the PTC heater 40 and the
long side of the heating-medium circulation box 10 as in the
related art. Therefore, the outer peripheral dimensions of the
heating-medium circulation box 10 can be brought close to the
planar outside dimensions of the PTC heater 40, and the width
dimension of the heating-medium circulation box 10 can be reduced,
and thus the manufacturing cost can be reduced.
[0078] Furthermore, in this heating-medium heating unit 10, since
the PTC devices 41a, 41b, and 41c that constitute the PTC heater 40
are disposed in a plurality of rows along the channel direction of
the heating-medium circulation passages (circulation paths 33 and
54), the plurality of PTC devices 41a, 41b, and 41c have different
widths, and the ON/OFF states of the PTC devices 41a, 41b, and 41c
can be individually controlled, the wiring members 40b can be
easily provided together at one end of the PTC devices 41a, 41b,
and 41c in the longitudinal direction, the quantity of heat from
the PTC heater 40 can be controlled with a simple configuration,
and thus a reduction in the manufacturing cost due to the size
reduction of the heating-medium heating unit 10 and enhanced
reliability can be achieved.
[0079] Furthermore, since the vehicle air conditioner 1 according
to the present invention is provided with the blower 4 that
circulates outside air or vehicle interior air, the cooler 5
provided downstream of the blower 4, and the radiator 6 provided
downstream of the cooler 5 and is configured to circulate engine
coolant heated by the heating-medium heating unit 10 according to
the present invention through the radiator 6, the reliability of
the heating-medium heating unit 10 can be enhanced, and
furthermore, the reliability of the entire vehicle air conditioner
1 can be enhanced while achieving miniaturization of the
heating-medium heating unit 10 and a reduction in the manufacturing
cost.
[0080] Although this embodiment has been described as applied to an
example in which the heating-medium heating unit is used in a
vehicle air conditioner, the heating-medium heating unit according
to the present invention may be applied to air conditioners that
are not designed for vehicles, heaters, refrigerators and so
on.
REFERENCE SIGNS LIST
[0081] 1 vehicle air conditioner [0082] 4 blower [0083] 5 cooler
[0084] 6 radiator [0085] 10 heating-medium heating unit [0086] 20
board-accommodating box serving as box component [0087] 21 cap
serving as box component [0088] 22 control board for controlling
PTC heater [0089] 28 wire insertion hole serving as portion
communicating with board-accommodating space [0090] 30 upper
heating-medium circulation box serving as box component [0091] 33
circulation path serving as heating-medium circulation passage
[0092] 38 radiating surface PTC heater [0093] 40b wiring member of
PTC heater [0094] 41a, 41b, 41c PTC device [0095] 50 lower
heating-medium circulation box serving as box component [0096] 51
cap serving as box component [0097] 54 circulation path serving as
heating-medium circulation passage [0098] 56 radiating surface
[0099] A first heating-medium circulation box [0100] B second
heating-medium circulation box [0101] C1, C2 joining-surface
cooling channel [0102] M1 to M4 joining surface [0103] M3a outside
sealing section [0104] M3b board sealing section [0105] S
board-accommodating space [0106] W1 width of outside sealing
section [0107] W2 width of board sealing section
* * * * *