U.S. patent application number 12/908490 was filed with the patent office on 2011-04-21 for heater particularly for a motor vehicle hvac system.
Invention is credited to Thomas Blum, Michel Brun.
Application Number | 20110091190 12/908490 |
Document ID | / |
Family ID | 41818722 |
Filed Date | 2011-04-21 |
United States Patent
Application |
20110091190 |
Kind Code |
A1 |
Blum; Thomas ; et
al. |
April 21, 2011 |
HEATER PARTICULARLY FOR A MOTOR VEHICLE HVAC SYSTEM
Abstract
A motor vehicle HVAC unit includes a housing, preferably a fan,
preferably a coolant evaporator for cooling air to be supplied to
the vehicle interior, at least two electric resistance heaters for
heating the air to be supplied to the vehicle interior and at least
one delay circuit, preferably two delay circuits. The at least two
electric resistance heaters are suppliable with electric current,
and a device is provided for supplying current to at least one of
the at least two electric resistance heaters with a time delay
relative to another electric resistance heater, and during the
turning on or supplying current to the electric resistance heaters
a small maximum current peak requirement is to occur at low
technical expenditures.
Inventors: |
Blum; Thomas; (Soultzmatt,
FR) ; Brun; Michel; (Rustenhart, FR) |
Family ID: |
41818722 |
Appl. No.: |
12/908490 |
Filed: |
October 20, 2010 |
Current U.S.
Class: |
392/465 |
Current CPC
Class: |
H05B 1/0236 20130101;
H05B 2203/02 20130101 |
Class at
Publication: |
392/465 |
International
Class: |
F24H 3/00 20060101
F24H003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 21, 2009 |
EP |
EP 09290807.8 |
Claims
1. A heater comprising: at least two electric resistance heaters
for heating the air to be supplied to the vehicle interior, whereby
the at least two electric resistance heaters can be supplied with
electric current, and a device for supplying current to at least
one electric resistance heater with a time delay relative to
another electric resistance heater, wherein the device comprises at
least one delay circuit, preferably two delay circuits.
2. The heater according to claim 1, wherein the at least one delay
circuit is at least one, particularly exclusively, analog delay
circuit and/or the at least one delay circuit has no processor
and/or no program can be run by the at least one delay circuit
and/or the at least one delay circuit is an electrical and/or
electronic circuit, particularly without a processor.
3. The heater according to claim 1, wherein the at least one delay
circuit comprises at least one capacitor and/or at least one
resistor.
4. The heater according to claim 3, wherein the at least one delay
circuit comprises exclusively at least one capacitor and/or at
least one resistor as electric and/or electronic components.
5. The heater according to claim 1, wherein the at least two
electric resistance heaters can be supplied with electric current
in pulse width modulation.
6. The heater according to claim 5, wherein a first one of the at
least two electric resistance heaters can be supplied with
pulse-width-modulated current delayed in time relative to another
one of the at least two electric resistance heaters with the at
least one delay circuit.
7. The heater according to claim 1, wherein at least one of the at
least two electric resistance heaters is at least one PTC
heater.
8. The heater according to claim 1, wherein the at least two
electric resistance heaters are connected electrically
parallel.
9. The heater according to claim 8, wherein each of the parallel
connected electric resistance heaters are each connected to a
parallel power line and the parallel power lines are connected to a
central power line.
10. The heater according to claim 8, wherein in parallel connected
electric resistance heaters one delay circuit each is connected in
series to the parallel connected electric resistance heaters.
11. The heater according to claim 10, characterized in that at
least two delay circuit devices are connected parallel and/or in
series.
12. A method for operating a heater, particularly for a vehicle
HVAC system according to claim 1, comprising the steps: conduction
of electric current through at least two electric resistance
heaters, preferably conduction of air through the heater,
generation of thermal energy by the at least two electric
resistance heaters by converting electrical energy into thermal
energy, preferably the transfer of the thermal energy generated by
the at least two electric resistance heaters to the air to be
heated, so that the air becomes heated, whereby during the
supplying of current to the at least two electric resistance
heaters, at least one electric resistance heater is supplied with
current delayed in time relative to another electric resistance
heater, in order to reduce the maximum current peak requirement for
the at least two electric resistance heaters during the supplying
of current and/or turning on of the at least two electric
resistance heaters, wherein the current is delayed in an analog
manner and/or the current is delayed without a program or software
being run.
13. The method according to claim 12, wherein the current is
delayed exclusively in an analog manner, particularly by at least
one delay circuit.
14. The method according to claim 12, wherein the current passed
through the at least two electric resistance heaters is
pulse-width-modulated and preferably the pulse width modulation is
changed, particularly the turn-on and turn-off times are changed,
in order to control and/or to regulate the electric power of the at
least two electric resistance heaters.
15. The method according to claim 12, wherein the current is
delayed by at least one delay circuit in each case for one electric
resistance heater.
Description
[0001] This nonprovisional application claims priority under 35
U.S.C. .sctn.119(a) to European Patent Application No.
EP09290807.8, which was filed on Oct. 21, 2009, and which is herein
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a heater particularly for a motor
vehicle HVAC system according to the preamble of claim 1 and to a
method for operating a heater of this type according to the
preamble of claim 12.
[0004] 2. Description of the Background Art
[0005] Motor vehicle HVAC systems are used for heating and cooling
air that is supplied to the interior of a motor vehicle. In this
regard, electric heaters or resistance heaters are used for heating
the air, particularly in hybrid or electric vehicles. An electric
current is passed through the electric resistance heaters and
because of the electric resistance of the electric resistance
heaters, they become heated, so that the air supplied to the
vehicle interior can be heated by passing the air past the electric
resistance heaters.
[0006] To control different heat outputs of the electric resistance
heaters, the electric resistance heaters are supplied with current
in pulse width modulation (PWM). When the electric resistance
heaters are supplied with pulse-width-modulated current, the
electric heat output of the electric resistance heaters is
controlled to the effect that the pulse width modulation is
changed. This means that for an increase in the electric heat
output the turn-on time is lengthened and the turn-off time
shortened and conversely during a reduction of the electric heat
output the turn-on time is shortened and the turn-off time
increased. The electric current for the electric resistance heaters
originates from an on-board electrical system as the current source
of the motor vehicle. In order not to have a very large maximum
current peak requirement for all electric resistance heaters during
turning on or supplying current to the electric resistance heaters,
i.e., at the beginning of the turn-on time of the
pulse-width-modulated current, the pulse-width-modulated current
before being supplied to the individual electric resistance heaters
is delayed in time by a microcontroller. The electric resistance
heaters thereby have turn-on times that are not simultaneous but
delayed in time and thereby sequential in time. The maximum current
peak requirement for the electric resistance heaters can be reduced
thereby, because all electric resistance heaters are not turned on
or supplied with current at the same time; i.e., the turn-on times
of the electric resistance heaters are not identical.
[0007] The microcontroller, which generally has a processor and
thereby can run a program or software, is thereby generally
arranged in the motor vehicle HVAC system, particularly in the area
of the electric resistance heaters. Microcontrollers of this type
are time-consuming to produce, however, and thereby expensive and
thereby in addition prone to failure during operation.
SUMMARY OF THE INVENTION
[0008] It is therefore an object of the present invention to
provide a heater particularly for motor vehicle HVAC units and a
method for operating a heater of this type, in which heater and
method during the turning on or supplying of electric resistance
heaters with current, a small maximum peak current requirement
occurs at low technical cost. The heater should be inexpensive to
produce and reliable to operate.
[0009] This object is achieved with a heater, particularly for an
HVAC unit, comprising a housing, preferably a fan, preferably a
coolant evaporator for cooling air to be supplied to the vehicle
interior, at least two electric resistance heaters for heating the
air to be supplied to the vehicle interior, whereby the at least
two electric resistance heaters can be supplied with electric
current, and a device for supplying current to at least one
electric resistance heater with a time delay relative to another
electric resistance heater, whereby the device comprises at least
one delay circuit, preferably two delay circuits, and/or the device
comprises at least one delay circuit, preferably two delay
circuits.
[0010] In particular, the at least one delay circuit is at least
one, particularly exclusively, analog delay circuit and/or the at
least one delay circuit has no processor and/or no program can be
run by the at least one delay circuit and/or the at least one delay
circuit is an electric and/or electronic circuit, particularly
without a processor. Therefore no digital signals or information
can be processed in the at least one delay circuit. The delay
circuit is therefore an electric and/or electronic circuit with a
very simple structure, which in particular has no processor.
Therefore, the delay circuit can be produced simply and at
reasonable cost, so that the high cost for an expensive and
time-consuming microcontroller can be economized.
[0011] In another embodiment, the at least one delay circuit
comprises at least one capacitor and/or at least one resistor. It
is also possible to provide an inductor in addition.
[0012] In a supplementary embodiment, the at least one delay
circuit comprises exclusively at least one capacitor and/or at
least one resistor as an electric and/or electronic component.
Because simple electronic components are used, for example, a
capacitor and a resistor, the delay circuit can be produced simply
and at reasonable cost.
[0013] Preferably, the at least one electric resistance heater can
be supplied with electric current in pulse width modulation. The
supplying of the at least two electric resistance heaters with
current therefore corresponds to the passing of current through the
at least two electric resistance heaters during the turn-on times
of the pulse-width-modulated current.
[0014] In a variant, at least one electric resistance heater can be
supplied with pulse-width-modulated current delayed in time
relative to another electric resistance heater with the at least
one delay circuit. The maximum current peak requirement for the at
least two electric resistance heaters, particularly for all
electric resistance heaters, can be reduced thereby at the
beginning of the turn-on times.
[0015] Expediently, the at least one electric resistance heater is
at least one PTC heater. It is especially advantageous, in this
case, if the at least one resistance heater or a majority of
electric resistance heaters are combined into a module and
advantageously the electric control unit can be or is connected to
this module. An electric resistance heater is then, so to speak, a
heating section of the module.
[0016] In another embodiment, the at least two electric resistance
heaters are connected electrically parallel.
[0017] In another embodiment, each of the parallel connected
electric resistance heaters are each connected to a parallel power
line and the parallel power lines are connected to a central power
line.
[0018] In a further embodiment, in parallel connected electric
resistance heaters one delay circuit each is connected in series to
the parallel connected electric resistance heaters.
[0019] In a supplementary variant, at least two delay circuit
devices are connected parallel and/or in series.
[0020] The method of the invention for operating a heater,
particularly for a vehicle HVAC system, particularly comprises the
steps: conduction of electric current through at least two electric
resistance heaters, preferably conduction of air through the heater
of the vehicle HVAC system, generation of thermal energy by the at
least two electric resistance heaters by converting electrical
energy into thermal energy, preferably the transfer of the thermal
energy generated by the at least two electric resistance heaters to
the air to be heated, which preferably is passed through the
vehicle HVAC system, so that the air becomes heated, whereby during
the supplying of current to the at least two electric resistance
heaters, at least one electric resistance heater is supplied with
current delayed in time relative to another electric resistance
heater, in order to reduce the maximum current peak requirement for
the at least two electric resistance heaters during the supplying
of current and/or the turning on of the at least two electric
resistance heaters, whereby the current is delayed in an analog
manner and/or the current is delayed without a program or software
being run.
[0021] In another embodiment, the current is delayed exclusively in
an analog manner, particularly by at least one delay circuit.
[0022] In particular, the current passed through the at least two
electric resistance heaters is pulse-width-modulated and preferably
the pulse width modulation is changed, particularly the turn-on and
turn-off times are changed, in order to control and/or to regulate
the electric power of the at least two electric resistance
heaters.
[0023] In another embodiment, the current is delayed by at least
one delay circuit in each case for one electric resistance
heater.
[0024] In another embodiment, the at least two electric resistance
heaters are supplied with current in the high voltage range, for
example, with a voltage of at least 60 V, 200 V, or 300 V.
[0025] Expediently, the vehicle HVAC system comprises at least one
air guiding device, particularly a ventilation flap, and/or at
least one air passage and/or at least one heat exchanger through
which coolant from a combustion engine flows, for heating the air
supplied to the vehicle interior, and/or a control unit.
[0026] In a supplementary variant, cooling fins are arranged at the
at least two electric resistance heaters, in order to increase the
surface for heating the air by current passed through the two
electric resistance heaters.
[0027] PTC heaters (PTC: Positive Temperature Coefficient) are
current- conducting materials that have an electric resistance and
can conduct current better at lower temperatures than at higher
temperatures. Their electric resistance therefore increases with
increasing temperature. The PTC heater generally comprises ceramic,
which is a PTC thermistor. Independent of the boundary conditions,
such as, e.g., applied voltage, nominal resistance, or volume of
air at the PTC heater, a very uniform surface temperature arises at
the PTC heater.
[0028] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus, are
not limitive of the present invention, and wherein:
[0030] FIG. 1 shows a circuit arrangement with three electric
resistance heaters and two delay circuits in a first exemplary
embodiment;
[0031] FIG. 2 shows a circuit arrangement with three electric
resistance heaters and two delay circuits in a second exemplary
embodiment; and
[0032] FIG. 3 shows the time voltage course of a
pulse-width-modulated current for the three electric resistance
heaters.
DETAILED DESCRIPTION
[0033] A circuit arrangement with three resistance heaters 1,
formed as PTC heaters 2, is shown in FIG. 1, particularly for a
vehicle HVAC unit (not shown) for heating the air passed through
the vehicle HVAC unit.
[0034] PTC heaters 2 are connected parallel in this case and are
supplied with electric current by a current source 4, namely, an
on-board electrical system 5 of the motor vehicle outside the
vehicle HVAC system. Current source 4 in this case provides current
in pulse width modulation. In this regard, the current in pulse
width modulation is passed from current source 4 through central
power lines 8, as power lines 6, to parallel power lines 7. The
electric current in pulse width modulation is passed through PTC
heaters 2 by parallel power lines 7. A delay circuit 3 in each case
is built into two of the three parallel power lines 7. Delay
circuit 3 has no processor, i.e., therefore also cannot run any
program or software, and is substantially equipped with simple
electric and/or electronic components, for example, at least one
capacitor and/or at least one resistor. Delay circuit 3 is
therefore especially simple and inexpensive to produce.
[0035] The time voltage course of the current passed through the
three PTC heaters 2 in pulse width modulation is shown in FIG. 3.
Here, the time t is plotted on the abscissa, i.e., the horizontal
axis. The electric current is passed through PTC heaters 2 in pulse
modulation; i.e., during a turn-on time T.sub.e, current is passed
through PTC heaters 2 and during a turn-off time T.sub.a no current
is passed through PTC heaters 2. The duration of the turn-on time
T.sub.e and the turn-off time T.sub.a in this regard can be changed
by current source 4 and thereby the electric heat output of PTC
heaters 2 is changed. The longer the turn-on times T.sub.e and the
shorter the turn-off times T.sub.a, the higher the electric heat
output provided by PTC heaters 2 and conversely. Therefore, during
the supplying of current or turning on of PTC heaters 2--i.e., at
the beginning of the turn-on time point T.sub.e, the start of the
supplying of current or the start of the turn-on times T.sub.e does
not occur simultaneously in all PTC heaters 2--the current provided
by current source 4 in pulse width modulation is delayed in time by
delay circuits 3. The time voltage course of the
pulse-width-modulated current for the PTC heater 2, shown at the
top in FIG. 1, is shown in the bottom curve in FIG. 3. The middle
curve in FIG. 3 shows the time voltage course of the
pulse-width-modulated current for the middle PTC heater in FIG. 1
and the top curve in FIG. 3 shows the time voltage curve of the
pulse-width-modulated current of PTC heaters 2 shown at the bottom
in FIG. 1. The start of the turn-on time T.sub.e here is delayed in
each case by a delay time .DELTA.t. Delay circuit 3 for the middle
PTC heater, shown in FIG. 1, thereby delays the current provided by
current source 4 by the delay time .DELTA.t and the delay circuit
3, for the bottom PTC heater 2 in FIG. 1, therefore delays the
current from current source 4 by two delay times .DELTA.t. A phase
offset of the pulse-width-modulated current therefore occurs in PTC
heaters 2 and parallel power lines 7. The maximum current peak
requirement for the three PTC heaters 2 at the beginning of the
turn-on times T.sub.e can be reduced thereby.
[0036] The circuit arrangement with three PTC heaters 2 and two
delay circuits 3 is shown in a second exemplary embodiment in FIG.
2. Substantially only the differences with respect to the first
exemplary embodiment according to FIG. 1 will be described below.
Delay circuit 3 for PTC heater 2, shown at the bottom in FIG. 2, is
not connected directly to central power line 8, but is connected to
parallel power line 7 between delay circuit 3 and middle PTC heater
2. Delay circuit 3 therefore receives the already delayed current,
which has been delayed by delay circuit 3 for the middle PTC heater
2. The delay times .DELTA.t of delay circuits 3 for the middle PTC
heater 2 and for the bottom PTC heater 2 are thereby the same.
Because of the supplying of delay circuit 3 for the bottom PTC
heater 2 with the already delayed current from delay circuit 3 of
the middle PTC heater 2, also in the second exemplary embodiment
the time voltage course of the pulse-width-modulated current, shown
in FIG. 3, occurs again in the three electric resistance heaters 1,
although both delay circuits 3 have the same delay times
.DELTA.t.
[0037] Overall, substantial advantages are associated with the
vehicle HVAC system of the invention and the method of the
invention for operating a vehicle HVAC system. Instead of using a
time-consuming and costly microcontroller as a device for supplying
the electric resistance heaters 1 with electric current in a
delayed manner, as occurs in the state of the art, a simple and
inexpensive delay circuit 3 with an analog structure is used, so
that considerable manufacturing costs can be saved as a result.
[0038] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are to be included within the scope of the following
claims.
* * * * *