U.S. patent application number 15/442045 was filed with the patent office on 2017-08-31 for method for driving an actuator of an hvac system.
The applicant listed for this patent is Johnson Electric S.A.. Invention is credited to Yvan BOURQUI.
Application Number | 20170246931 15/442045 |
Document ID | / |
Family ID | 55806925 |
Filed Date | 2017-08-31 |
United States Patent
Application |
20170246931 |
Kind Code |
A1 |
BOURQUI; Yvan |
August 31, 2017 |
METHOD FOR DRIVING AN ACTUATOR OF AN HVAC SYSTEM
Abstract
A method for driving an actuator of an HVAC system is provided,
and which comprises the steps of: a] determining an actuation
command to the actuator; and b] ramping a drive power to the
actuator between a steady-state-velocity drive power and a
zero-velocity drive power to effect a required acceleration or
deceleration to a movable member of the HAVC system without or
substantially without over-powering of the actuator. An HVAC system
is also provided. The HVAC system implementing the above method is
not only capable of reducing the noise produced by an HVAC system,
but is also capable of reducing an over-powering of the actuator
when there is a low load on the system.
Inventors: |
BOURQUI; Yvan; (Corminboeuf,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Johnson Electric S.A. |
Murten |
|
CH |
|
|
Family ID: |
55806925 |
Appl. No.: |
15/442045 |
Filed: |
February 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60H 1/00857 20130101;
H02P 23/20 20160201; B60H 1/3414 20130101; B60H 1/00871 20130101;
B60H 2001/3471 20130101 |
International
Class: |
B60H 1/00 20060101
B60H001/00; H02P 23/20 20060101 H02P023/20; B60H 1/34 20060101
B60H001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2016 |
GB |
1603283.1 |
Claims
1. A method for driving an actuator of an HVAC system, the method
comprising the steps of: a] deter mining an actuation command to
the actuator; and b] ramping a drive power to the actuator between
a steady-state-velocity drive power and a zero-velocity drive power
to effect a required acceleration or deceleration to a movable
member of the HAVC system without or substantially without
over-powering of the actuator.
2. The method as claimed in claim 1, wherein the drive power to the
actuator is smoothly ramped.
3. The method as claimed in claim 1, wherein the actuation command
is at least one of initialisation command, final deactivation
command and directional-change command to the actuator.
4. The method as claimed in claim 1, wherein, during the step b],
the drive power is increased from a zero-velocity drive power until
the movable member begins moving.
5. The method as claimed in claim 4, wherein, the step b] further
comprising the step of monitoring a position of the movable member,
wherein the position of the movable member is indirectly monitored
via a position sensor associated with the actuator.
6. The method as claimed in claim 1, further comprising a step
prior to the step b] of calculating a required acceleration or
deceleration of the actuator to effect the actuation command at the
movable member.
7. The method as claimed in claim 1, wherein, during the step b],
the drive power to the actuator is automatically ramped between the
steady-state-velocity drive power and the zero-velocity drive power
upon mechanical play of the HVAC system.
8. The method as claimed in claim 7, wherein the mechanical play is
a lost motion of the movable member in the HVAC system caused by
many gaps between mechanical components, the method further
comprising obtaining positions and lengths of the gaps, during the
step b, ramping a drive power according to the positions and
lengths of the gaps.
9. The method as claimed in claim 7, further comprising obtaining a
parameter representing the mechanical play in the HVAC system,
during the step b, ramping a drive power according to the
parameter.
10. The method as claimed in claim 9, wherein the actuator
comprises at least one rotatable element, the parameter being a
total rotation angle of the rotatable element or a total rotation
angle of the movable member corresponding to the mechanical play;
during the step b, the change of the drive power based on the total
rotation angle of the rotatable element or the total rotation angle
of the movable member.
11. The method as claimed in claim 7, wherein an information of the
mechanical play is pre-programmed.
12. The method as claimed in claim 11, wherein the information of
the mechanical play is determined by machine learning during
operation or pre-testing of the HVAC system.
13. The method as claimed in claim 1, wherein during step b], the
required acceleration or deceleration is at least in part based on
a percentage of mechanical play which must be accommodated.
14. The method as claimed in claim 1, further comprising a step of
monitoring directionality of a travel of the actuator.
15. The method as claimed in claim 1, wherein the movable member of
the HVAC system comprises at least one HVAC vent flap.
16. A method for driving an actuator of an HVAC system, the method
comprising the steps of: a] determining a region of mechanical play
in a movable member of the HVAC system which is associated with the
actuator; b] monitoring a position of the movable member or at
least one rotatable element of the actuator to detetiiiine when the
region of mechanical play has been entered or exited; and c]
ramping a drive power to the actuator between a
steady-state-velocity drive power and a zero-velocity drive power
during the region of mechanical play so as to eliminate or reduce
over-powering of the actuator.
17. An HVAC system comprising: an actuator having an actuator
position sensor associated therewith; at least one HVAC vent flap
connected to the actuator via a movable member, the motion of the
movable member having a region of mechanical play therein; a
controller for controlling the actuator; and a memory circuit
associated with the controller and arranged to store information of
the region of mechanical play; the controller being adapted to ramp
a drive power to the actuator between a steady-state-velocity drive
power and a zero-velocity drive power when the actuator position
sensor determines that the motion of the movable member is within
the region of mechanical play.
18. The HVAC system as claimed in claim 17, wherein the mechanical
play is a lost motion of the movable member in the HVAC system
caused by many gaps between mechanical components, the memory
circuit is used for storing positions and lengths of the gaps, and
the controller is adapted to ramp a drive power according to the
positions and lengths of the gaps.
19. The HVAC system as claimed in claim 17, wherein the memory
circuit is used for storing a parameter representing the region of
mechanical play in the HVAC system, and the controller being
adapted to ramp a drive power according to the parameter.
20. The HVAC system as claimed in claim 19, wherein the actuator
comprises at least one rotatable element, the parameter being a
total rotation angle of the rotatable element or a total rotation
angle of the movable member corresponding to the region of
mechanical play; and the change of the drive power based on the
total rotation angle of the rotatable element or the total rotation
angle of the movable member.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional patent application claims priority
under 35 U.S.C. .sctn.119(a) from Patent Application No.
GB1603283.1 filed in British on Feb. 25, 2016, the entire contents
of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for driving an
actuator of a HAVC system. The method is cable of reducing noise
from a heating, ventilation, and air conditioning (HVAC) system,
and eliminating or reducing over-powering of an actuator of an HVAC
system, in particular for HVAC systems in motor vehicles. The
invention further relates to an HVAC system capable of performing
said method.
BACKGROUND OF THE INVENTION
[0003] HVAC systems are used to control for climate control, such
as in motor vehicles. Such HVAC systems utilise vent flaps which
can control a flow of air into or through an area to effect the
climate control. The positions of the vent flaps are typically
controlled by one or more actuators, positioning the vent flaps so
as to alter an air flow emergent from the HVAC system.
[0004] Generally, each such actuator is formed having an electric
motor adapted to control a gear chain through an actuator housing.
The gear chain is then generally directly or indirectly connected
to levers which interact with the vent flaps, such that the
actuation of the actuator can be transmitted to effect positional
change of the vent flaps.
[0005] Such HVAC systems, having a series of interlinked mechanical
components, have natural regions of mechanical play, wherein at
least part of the actuation must be used to relieve slack in the
system before any force can be transferred to the vent flaps. This
is most noticeable when the actuator is accelerated from zero
velocity, such as on initialisation of the actuator, or on
directional change. During the regions of mechanical play, the load
on the actuator is relatively low, and this manifests as a noise
output from the HVAC system; the actuator accelerates quickly
during the regions of mechanical play, resulting in the mechanical
components contacting one another with relatively high kinetic
energy.
SUMMARY OF THE INVENTION
[0006] The present invention seeks to provide a method for driving
an actuator of an HVAC system and an HVAC system capable of
performing said method which are capable of overcoming or obviating
the above-referenced problems.
[0007] According to a first aspect of the invention, the present
invention provides one method for driving an actuator of an HVAC
system, the method comprising the steps of: a] determining an
actuation command to the actuator; and b] ramping a drive power to
the actuator between a steady-state-velocity drive power and a
zero-velocity drive power to effect a required acceleration or
deceleration to a movable member of the HAVC system without or
substantially without over-powering of the actuator.
[0008] The present invention provides another method for driving an
actuator of an HVAC system, the method comprising the steps of: a]
determining a region of mechanical play in a movable member of the
HVAC system which is associated with the actuator; b] monitoring a
position of the movable member or at least one rotatable element of
the actuator to determine when the region of mechanical play has
been entered or exited; and c] ramping a drive power to the
actuator between a steady-state-velocity drive power and a
zero-velocity drive power during the region of mechanical play so
as to eliminate or reduce over-powering of the actuator.
[0009] According to a second aspect of the invention, the present
invention provides an HVAC system comprising: an actuator having an
actuator position sensor associated therewith; at least one HVAC
vent flap connected to the actuator via a movable member, the
motion of the movable member having a region of mechanical play
therein; a controller for controlling a position of the actuator;
and a memory circuit associated with the controller and arranged to
store information about the region of mechanical play; the
controller being adapted to ramp a drive power to the actuator
between a steady-state-velocity drive power and a zero-velocity
drive power when the actuator position sensor determines that the
motion of the movable member is within the region of mechanical
play.
[0010] The HVAC system implementing the above method is not only
capable of reducing the noise produced by an HVAC system , but is
also capable of reducing an over-powering of the actuator when
there is a low load on the system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a perspective representation of the preferred
embodiment of an HVAC system in accordance with the second aspect
of the invention;
[0012] FIG. 2 shows a perspective representation of the preferred
embodiment of one actuator of the HVAC system of FIG. 1;
[0013] FIG. 3a shows a qualitative graph of the drive power as
supplied to the actuator of the HVAC system of FIG. 1 versus time,
the dashed upper curve showing the drive power supplied in the
prior art, and the solid lower curve showing the drive power
supplied using a method in accordance with the first aspect of the
invention;
[0014] FIG. 3b shows a qualitative graph of the rotor velocity of
the actuator of the HVAC system of FIG. 1 if a drive power is
supplied in accordance with those shown in FIG. 3a, the dashed
upper curve showing the rotor velocity if powered in accordance
with the dashed curve of FIG. 3a, and the solid lower curve showing
the rotor velocity if powered in accordance with the solid curve of
FIG. 3a;
[0015] FIG. 4 shows a diagrammatic representation of the first
embodiment of a method for driving an actuator of an HVAC system in
accordance with the invention; and
[0016] FIG. 5 shows a diagrammatic representation of the second
embodiment of a method for driving an actuator of an HVAC system in
accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Referring firstly to FIG. 1, there is shown an HVAC system
globally at 10 which is arranged to substantially reduce the noise
output thereof. The HVAC system 10 indicated is shown as part of
the climate control system of a motor vehicle, though it will be
appreciated that the present invention could be utilised in any
context in which an HVAC system is utilised.
[0018] The HVAC system 10 includes at least one actuator 12; here
two actuators 12 are shown, which may be singularly or separately
controlled, though it will be apparent that any number of actuators
could be supplied, depending upon the requirements of the HVAC
system 10. Each actuator 12 is in communication with a movable
member, such as the levers 14 illustrated, which are in turn
associated with actuatable vent flaps 16 which can control the
passage of air through the HVAC system 10. Whilst singular,
unitarily formed levers 14 are shown, other forms of movable member
could be provided, such as gear trains. In any event, the
mechanical train from the actuators 12 to their respective vent
flaps 16 introduces a region of mechanical play, wherein the load
on the actuator 12 is reduced during movement, resulting in
ineffective transfer of force.
[0019] FIG. 2 shows the actuator 12 in more detail, a cover of an
actuator housing 18 having been removed to show the components
therein. The actuator 12 illustrated includes a drive mechanism,
preferably an electric motor 20 as shown, which can be controlled
by a, preferably onboard, controller 22.
[0020] The controller 22 may preferably be associated with a
position sensor 24, which is capable of determining the position of
a rotor of the electric motor 20, and thereby allow for indirect
calculation of the relative position of the vent flaps 16 in order
to determine control commands. It will be apparent, however, that
some form of position sensor could be provided elsewhere in the
mechanical train. For instance, a position sensor could be engaged
with the levers 14 or the vent flaps 16 if desired. In the present
embodiment, the position sensor 24 is formed as a Hall sensor
capable of readily determining the relative angular position of the
rotor of the electric motor 20.
[0021] The controller 22 may also include a memory circuit 26 which
is capable of storing informations relating to the region of
mechanical play in the HVAC system 10 to the controller 22. This
allows for the controller to account for the mechanical play in the
system when sending commands to the actuator 12. This information
may take the form of correlation data between a given rotor
position and the expected or calculated mechanical play or slack
which would be experienced for said rotor position. Furthermore,
there may be directionality information stored within the memory
circuit 26; the magnitude of mechanical play may be different
depending upon the direction in which the rotor had been previously
rotated, for example, and the directionality information may be
necessary in order to calculate the expected mechanical play.
[0022] The electric motor 20 includes an output 28 via which drive
can be transferred out of the actuator 12. In the present
embodiment, this output 28 comprises a toothed gear which is part
of a gear train 30. Other drive transmission means may be
considered, however. For example, a worm gear could be utilised in
lieu of the gear train 30.
[0023] Mechanical play is a lost motion of the movable member in
the HVAC system caused by many gaps between the mechanical
components. By obtaining a parameter representing the region of
mechanical play, such as positions and lengths of the gaps, total
rotation angle of at least one rotatable element of the actuator
corresponding to the region of mechanical play, the change of the
drive power can be optimized according to the parameter.
[0024] Preferably, using the position sensor 24 to detect a
position of at least one rotatable element of the actuator 12 or a
position of at least one movable member of the HAVC system 10, and
cacualting a velocity of the rotatable element or a velocity of the
movable member. Suddenly changes in the velocity of the rotatable
element or the movable member can be used to identify the
beginnings and endings of the region of mechanical play, so a total
rotation angle of the rotatable element or a total rotation angle
of the movable member representing the region of mechanical play
can be obtained through a series of tests. The at least one
rotatable element can be a rotor of the motor 20, the output 28, or
any gear of the gear train 30. The movable member can be the lever
14, the vent flap 16, or any movable member directly or indirectly
interacts with the actuator 12.
[0025] The HVAC system 10 is controllable so as to reduce the noise
emitted as the components thereof clash during the region of
mechanical play. The simplest scenario in which this can be
considered is in the initialisation of the actuator 12.
[0026] When the HVAC system 10 is first activated, the actuator 12
will be stationary, and there will likely be some effects due to
mechanical play in the actuator 12, levers 14 and flaps 16. In the
art, the electric motor of an actuator would be brought up to full
speed by driving the actuator at full power P1. This can be
visualised from the dashed upper curve DP in FIG. 3a, indicated
globally at 50. As the slack in the system due to the mechanical
play is overcome, the drive power will reach a steady-state
condition P2.
[0027] During the period of low-load on the system, that is,
between times T0 and T1 indicated in FIG. 3a, the noise emitted
from the HVAC system is relatively high, being proportional to the
drive power. The rotor velocity of such a system can be seen at the
dashed line RV in FIG. 3b, indicated globally at 60; the rotor
accelerates quickly to a peak velocity V1 whilst the load is
minimal, and then stabilises to a steady-state velocity V2.
[0028] In the present embodiment, the controller 22 sends an
actuation command to the electric motor 20, that is, an activation
command. However, based on the position of the actuator 12, levers
14 and/or vent flaps 16, as measured by the position sensor 24, and
potentially also the knowledge of the region of mechanical play,
the controller 22 may be able to calculate a required acceleration
of the rotor of the electric motor 20 so as to correctly move the
vent flaps 16. The controller 22 can do this in a controlled manner
by ramping, preferably in a slow, smooth manner, the drive power
supplied to the electric motor 20 from a zero-velocity drive power
P1' to a steady-state-velocity drive power P2', as shown by the
solid line DP'. This in turn effects the required acceleration
without or substantially without over-powering of the actuator 12
to thereby reduce a noise emitted by the HVAC system 10. The
respective rotor velocity RV' can be seen at the solid line in FIG.
3b, which ramps from zero velocity V1' to a steady-state velocity
V2'.
[0029] As can be seen, since the drive power supplied to the
electric motor 20 is such that the steady-state-velocity drive
power P2' is never exceeded, the over-powering of the system
associated with existing HVAC systems never occurs, and therefore
no excess noise is produced beyond that which would be produced
under the steady state condition.
[0030] It will be appreciated that the reverse methodology can be
applied to the deactivation of the actuator 12 of the HVAC system
10. Rather than abruptly stopping the actuator 12 when a target
position of the vent flaps 16 has been achieved, which may result
in over-powering as the load on the actuator 12 decreases, the
drive power can be slowly ramped down over time by the controller
22. This has the effect of producing a smooth stop of the actuation
of the vent flaps 16, thereby reducing the noise produced by the
whole HVAC system.
[0031] As such, the first embodiment of method for driving the
actuator 12 of the HVAC system 10 is therefore illustrated in FIG.
4, indicated globally at S100. The position of a movable member 14,
16 and/or the position of at least one rotatable element of the
actuator 12 of the HVAC system 10 can be monitored, step S101, for
instance, using a position sensor 24 such as the Hall sensor. An
actuation command can then be determined, step S102, to effect an
actuation of the actuator 12, such as acceleration or deceleration
as may be achieved on activation, deactivation or directional
change of the actuator 12.
[0032] A required acceleration or deceleration of the actuator 12
can then be calculated, step S103 which is capable of performing
the actuation command through the mechanical train to the vent
flaps 16, and, using a command from the controller 22, a drive
power to the actuator can be ramped, step S104, between a
steady-state-velocity drive power P2' and a zero-velocity drive
power P1' to effect the required acceleration or deceleration
without or substantially without over-powering of the actuator 12
to thereby reduce a noise emitted by the HVAC system 10. This may
be performed automatically as soon as a region of mechanical play
is entered, for example.
[0033] The term zero-velocity drive power P1' is intended to refer
to a state in which the actuator 12 is stationary; however, it will
be clear that this is not necessarily zero power, since some
actuators may require the presence of a holding current in order to
maintain an actuator position. Furthermore, a steady-state-velocity
drive power P2' is intended to refer to a drive power required to
effect motion of the movable member under a standard load, that is,
not under a reduced load which would be experienced ordinarily in
the region of mechanical play of the HVAC system 10.
[0034] It may be possible to pre-store the memory circuit 26 with
information regarding the exact position of the region of
mechanical play in the HVAC system 10, based on its manufacturing
parameters, for example, tolerance in the levers 14. This may be
achieved by, for example, pre-testing of the HVAC system 10 in a
learning phase, prior to installation and/or first operation of the
HVAC system 10, allowing the mechanical play to be scanned or
tested. However, it may additionally or alternatively be beneficial
to introduce a form of machine learning into the controller 22
logic, such that it is capable of calculating the position of the
region of mechanical play during operation, possibly by measurement
of the load on the actuator 12 with respect to the measured
position by the position sensor 24 and or based on any measured
directional information. Preferably, by obtaining a parameter
representing the region of the mechanical play, such as positions
and lengths of the gaps, total rotation angle of at least one
rotatable element of the actuator corresponding to the mechanical
play, the required acceleration or deceleration can be calculated
according to the parameter.
[0035] Preferably, using the position sensor 24 to detect a
position of at least one rotatable element or a position of at
least one movable member, and cacualting a velocity of the
rotatable element or a velocity of the movable member. Suddenly
changes in the velocity of the rotatable element or the movable
member can be used to identify the beginnings and endings of the
region of mechanical play, so a total rotation angle of the
rotatable element or a total rotation angle of the movable member
representing the region of mechanical play can be obtained through
a series of tests.
[0036] It will be apparent that if the information related to
region of mechanical play and/or the required acceleration and/or
deceleration based upon the region of mechanical play are prestored
in the memory circuit 26, the step S101 and the step S103 in the
FIG. 4 are not necessary, directly ramping the drive power to
actuator according to the required acceleration or deceleration
during the step S104.
[0037] The memory circuit 26 becomes more useful during normal
operation of the HVAC system 10, in which directional changes of
the vent flaps 16 may be more common than the activation and/or
deactivation commands. Where directional changes occur, there will,
at some point, be a passage through the region of mechanical play
in which over-powering of the actuator 12 would ordinarily be a
concern. In such a condition, it becomes more important to know
exactly where the mechanical play is in order for the controller 22
to be able to ramp the drive power up or down in order to
accelerate or decelerate the actuator 12 between the zero-velocity
drive power P1' and the steady-state-velocity drive power P2' or
vice versa.
[0038] As such, it will be apparent that initial activation and
final deactivation of the actuator 12 using ramped control of the
drive power may be performed independently of the knowledge of the
region of mechanical play in the HVAC system 10; it will always be
assumed that there will be some play in the HVAC system 10 under
these conditions. In a scenario of initial activating the actuator
12, only the step S101 and the step S104 are necessary. During the
step S101, monitoring the position of the movable member to
determine whether the movable member begins moving. During the step
S104, the drive power is increased from a zero-velocity drive power
until the movable member begins moving, thereby minimising the
noise from the HVAC system 10 and the drive power for the actuator
12.
[0039] The position of the region of mechanical play is important
during the normal operation of the actuator 12, particularly during
a directional change. At any given point, the rotor of the electric
motor 20 may come to a halt such that, upon activation there is
only a certain percentage of the mechanical play in the system
which must be accounted for when ramping the drive power. The
soft-starting of the actuator 12 ensures that regardless of the
position of the region of mechanical play, it is not brought up to
full rotor velocity RV' until the gear train 30 has been fully
engaged.
[0040] It will also be clear that the method of the present
invention is not only capable of reducing the noise produced by an
HVAC system 10, but is also capable of reducing an over-powering of
the actuator 12 when there is a low load on the system. The second
embodiment of method for driving the actuator 12 of the HVAC system
10 is therefore illustrated in FIG. 5, indicated globally at
S200.
[0041] Firstly, a region of mechanical play in a movable member 14,
16 of the HVAC system 10 which is associated with the actuator 12
can be determined, step S201. This may be pre-programmed into the
controller 22, or determined during use of the HVAC system 10 using
machine learning. A position of the movable member 14, 16 and/or
the position of at least one rotatable element of the actuator 12
can be monitored, step S202 so as to determine when region of
mechanical play has been entered or exited, and a drive power to
the actuator 12 can be ramped, step S203, between a
steady-state-velocity drive power P2' and a zero-velocity drive
power P1' during the region of mechanical play so as to eliminate
or reduce over-powering of the actuator 12.
[0042] It is therefore possible to provide a method of controlling
the actuator of an HVAC system so as to reduce the noise emitted
therefrom, and also to reduce the energy consumption of the device
by eliminating or reducing over-powering of the actuator. This can
be achieved by providing logic within a controller which is
arranged to provide a soft-start to the actuator, in particular so
as to accommodate the mechanical play within the system which would
otherwise result in a low load on the actuator in use.
[0043] The words `comprises/comprising` and the words
`having/including` when used herein with reference to the present
invention are used to specify the presence of stated features,
integers, steps or components, but do not preclude the presence or
addition of one or more other features, integers, steps, components
or groups thereof.
[0044] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
sub-combination.
[0045] The embodiments described above are provided by way of
examples only, and various other modifications will be apparent to
persons skilled in the field without departing from the scope of
the invention as defined herein.
* * * * *